Version 3.21.0

Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>
CHANGELOG.md: Add entry for PR #505
2026-07-03 14:05:11 +02:00 · 2025-08-23 21:18:59 -04:00 · 2025-08-23 20:15:19 -04:00 · 2025-08-23 20:14:52 -04:00 · 2025-08-23 20:08:01 -04:00 · 2025-08-23 20:03:33 -04:00
35 changed files with 2041 additions and 1422 deletions
@@ -18,6 +18,8 @@ jobs:
      CARGO_TERM_COLOR: always
      # https://github.com/rust-lang/rust/issues/78210
      RUSTFLAGS: -C strip=symbols -C target-feature=+crt-static
+      # https://github.com/rust-lang/cargo/pull/15462
+      RUSTDOCFLAGS: -C target-feature=+crt-static
      TARGETS: ${{ join(matrix.artifact.targets, ' ') || matrix.artifact.name }}
      ANDROID_API: ${{ matrix.artifact.android_api }}
    strategy:
@@ -7,6 +7,13 @@
    to update the actual links at the bottom of the file.
 -->

+### Version 3.21.0
+
+* Switch to using rawzip for zip parsing and writing ([PR #489])
+* Various code improvements ([PR #492], [PR #495], [PR #496], [PR #497], [PR #499], [PR #500], [PR #501], [PR #502], [PR #503], [PR #505])
+* Update dependencies ([PR #498])
+* Fix patching older OTAs with payloads using CoW v2 without the compression factor field ([Issue #493], [PR #504])
+
 ### Version 3.20.0

 * Switch to using lzma-rust2 for XZ compression and decompression ([PR #483])
@@ -401,6 +408,7 @@ Behind-the-scenes changes:
 [Issue #469]: https://github.com/chenxiaolong/avbroot/issues/469
 [Issue #472]: https://github.com/chenxiaolong/avbroot/issues/472
 [Issue #482]: https://github.com/chenxiaolong/avbroot/issues/482
+[Issue #493]: https://github.com/chenxiaolong/avbroot/issues/493
 [PR #130]: https://github.com/chenxiaolong/avbroot/pull/130
 [PR #132]: https://github.com/chenxiaolong/avbroot/pull/132
 [PR #133]: https://github.com/chenxiaolong/avbroot/pull/133
@@ -581,3 +589,16 @@ Behind-the-scenes changes:
 [PR #485]: https://github.com/chenxiaolong/avbroot/pull/485
 [PR #486]: https://github.com/chenxiaolong/avbroot/pull/486
 [PR #487]: https://github.com/chenxiaolong/avbroot/pull/487
+[PR #489]: https://github.com/chenxiaolong/avbroot/pull/489
+[PR #492]: https://github.com/chenxiaolong/avbroot/pull/492
+[PR #495]: https://github.com/chenxiaolong/avbroot/pull/495
+[PR #496]: https://github.com/chenxiaolong/avbroot/pull/496
+[PR #497]: https://github.com/chenxiaolong/avbroot/pull/497
+[PR #498]: https://github.com/chenxiaolong/avbroot/pull/498
+[PR #499]: https://github.com/chenxiaolong/avbroot/pull/499
+[PR #500]: https://github.com/chenxiaolong/avbroot/pull/500
+[PR #501]: https://github.com/chenxiaolong/avbroot/pull/501
+[PR #502]: https://github.com/chenxiaolong/avbroot/pull/502
+[PR #503]: https://github.com/chenxiaolong/avbroot/pull/503
+[PR #504]: https://github.com/chenxiaolong/avbroot/pull/504
+[PR #505]: https://github.com/chenxiaolong/avbroot/pull/505
@@ -80,18 +80,15 @@ dependencies = [

 [[package]]
 name = "anyhow"
-version = "1.0.98"
+version = "1.0.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e16d2d3311acee920a9eb8d33b8cbc1787ce4a264e85f964c2404b969bdcd487"
+checksum = "b0674a1ddeecb70197781e945de4b3b8ffb61fa939a5597bcf48503737663100"

 [[package]]
 name = "arbitrary"
-version = "1.4.1"
+version = "1.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dde20b3d026af13f561bdd0f15edf01fc734f0dafcedbaf42bba506a9517f223"
-dependencies = [
- "derive_arbitrary",
-]
+checksum = "c3d036a3c4ab069c7b410a2ce876bd74808d2d0888a82667669f8e783a898bf1"

 [[package]]
 name = "assert_matches"
@@ -107,7 +104,7 @@ checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"

 [[package]]
 name = "avbroot"
-version = "3.20.0"
+version = "3.21.0"
 dependencies = [
 "anyhow",
 "assert_matches",
@@ -139,6 +136,7 @@ dependencies = [
 "prost-build",
 "protox",
 "rand",
+ "rawzip",
 "rayon",
 "regex",
 "ring",
@@ -157,7 +155,6 @@ dependencies = [
 "x509-cert",
 "zerocopy",
 "zerocopy-derive",
- "zip",
 ]

 [[package]]
@@ -195,14 +192,14 @@ dependencies = [
 "regex",
 "rustc-hash",
 "shlex",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
 name = "bitflags"
-version = "2.9.1"
+version = "2.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1b8e56985ec62d17e9c1001dc89c88ecd7dc08e47eba5ec7c29c7b5eeecde967"
+checksum = "34efbcccd345379ca2868b2b2c9d3782e9cc58ba87bc7d79d5b53d9c9ae6f25d"
 dependencies = [
 "serde",
 ]
@@ -236,12 +233,6 @@ dependencies = [
 "serde",
 ]

-[[package]]
-name = "bumpalo"
-version = "3.19.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "46c5e41b57b8bba42a04676d81cb89e9ee8e859a1a66f80a5a72e1cb76b34d43"
-
 [[package]]
 name = "byteorder"
 version = "1.5.0"
@@ -274,9 +265,9 @@ dependencies = [

 [[package]]
 name = "cc"
-version = "1.2.32"
+version = "1.2.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2352e5597e9c544d5e6d9c95190d5d27738ade584fa8db0a16e130e5c2b5296e"
+checksum = "42bc4aea80032b7bf409b0bc7ccad88853858911b7713a8062fdc0623867bedc"
 dependencies = [
 "shlex",
 ]
@@ -292,9 +283,9 @@ dependencies = [

 [[package]]
 name = "cfg-if"
-version = "1.0.1"
+version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9555578bc9e57714c812a1f84e4fc5b4d21fcb063490c624de019f7464c91268"
+checksum = "2fd1289c04a9ea8cb22300a459a72a385d7c73d3259e2ed7dcb2af674838cfa9"

 [[package]]
 name = "cfg_aliases"
@@ -325,9 +316,9 @@ dependencies = [

 [[package]]
 name = "clap"
-version = "4.5.43"
+version = "4.5.45"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "50fd97c9dc2399518aa331917ac6f274280ec5eb34e555dd291899745c48ec6f"
+checksum = "1fc0e74a703892159f5ae7d3aac52c8e6c392f5ae5f359c70b5881d60aaac318"
 dependencies = [
 "clap_builder",
 "clap_derive",
@@ -335,9 +326,9 @@ dependencies = [

 [[package]]
 name = "clap_builder"
-version = "4.5.43"
+version = "4.5.44"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c35b5830294e1fa0462034af85cc95225a4cb07092c088c55bda3147cfcd8f65"
+checksum = "b3e7f4214277f3c7aa526a59dd3fbe306a370daee1f8b7b8c987069cd8e888a8"
 dependencies = [
 "anstream",
 "anstyle",
@@ -347,23 +338,23 @@ dependencies = [

 [[package]]
 name = "clap_complete"
-version = "4.5.56"
+version = "4.5.57"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "67e4efcbb5da11a92e8a609233aa1e8a7d91e38de0be865f016d14700d45a7fd"
+checksum = "4d9501bd3f5f09f7bbee01da9a511073ed30a80cd7a509f1214bb74eadea71ad"
 dependencies = [
 "clap",
 ]

 [[package]]
 name = "clap_derive"
-version = "4.5.41"
+version = "4.5.45"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ef4f52386a59ca4c860f7393bcf8abd8dfd91ecccc0f774635ff68e92eeef491"
+checksum = "14cb31bb0a7d536caef2639baa7fad459e15c3144efefa6dbd1c84562c4739f6"
 dependencies = [
 "heck",
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -536,18 +527,7 @@ checksum = "8034092389675178f570469e6c3b0465d3d30b4505c294a6550db47f3c17ad18"
 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.104",
-]
-
-[[package]]
-name = "derive_arbitrary"
-version = "1.4.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "30542c1ad912e0e3d22a1935c290e12e8a29d704a420177a31faad4a601a0800"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -570,13 +550,14 @@ checksum = "ecb08c4819242b1ec89b3d0c6affa229005bef46ae4f7eed8b80768187c10087"

 [[package]]
 name = "e2e"
-version = "3.20.0"
+version = "3.21.0"
 dependencies = [
 "anyhow",
 "avbroot",
 "clap",
 "ctrlc",
 "hex",
+ "rawzip",
 "ring",
 "rsa",
 "serde",
@@ -586,7 +567,6 @@ dependencies = [
 "tracing",
 "tracing-subscriber",
 "x509-cert",
- "zip",
 ]

 [[package]]
@@ -654,7 +634,7 @@ checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"

 [[package]]
 name = "fuzz"
-version = "3.20.0"
+version = "3.21.0"
 dependencies = [
 "avbroot",
 "honggfuzz",
@@ -718,9 +698,9 @@ dependencies = [

 [[package]]
 name = "glob"
-version = "0.3.2"
+version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a8d1add55171497b4705a648c6b583acafb01d58050a51727785f0b2c8e0a2b2"
+checksum = "0cc23270f6e1808e30a928bdc84dea0b9b4136a8bc82338574f23baf47bbd280"

 [[package]]
 name = "hashbrown"
@@ -773,9 +753,9 @@ checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"

 [[package]]
 name = "indexmap"
-version = "2.10.0"
+version = "2.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fe4cd85333e22411419a0bcae1297d25e58c9443848b11dc6a86fefe8c78a661"
+checksum = "f2481980430f9f78649238835720ddccc57e52df14ffce1c6f37391d61b563e9"
 dependencies = [
 "equivalent",
 "hashbrown",
@@ -832,9 +812,9 @@ checksum = "2c4a545a15244c7d945065b5d392b2d2d7f21526fba56ce51467b06ed445e8f7"

 [[package]]
 name = "libc"
-version = "0.2.174"
+version = "0.2.175"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1171693293099992e19cddea4e8b849964e9846f4acee11b3948bcc337be8776"
+checksum = "6a82ae493e598baaea5209805c49bbf2ea7de956d50d7da0da1164f9c6d28543"

 [[package]]
 name = "libloading"
@@ -895,7 +875,7 @@ dependencies = [
 "quote",
 "regex-syntax",
 "rustc_version",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -918,9 +898,9 @@ dependencies = [

 [[package]]
 name = "lzma-rust2"
-version = "0.8.0"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a82192ab5b40bc95fff6e8a61e099e421f07055778b2f5261297c102137b6081"
+checksum = "fb31493965215fc8d0956b8dd58f2609e17ea89487a5cb2619e1d60b8b71328f"
 dependencies = [
 "crc",
 "sha2",
@@ -934,9 +914,9 @@ checksum = "32a282da65faaf38286cf3be983213fcf1d2e2a58700e808f83f4ea9a4804bc0"

 [[package]]
 name = "memmap2"
-version = "0.9.7"
+version = "0.9.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "483758ad303d734cec05e5c12b41d7e93e6a6390c5e9dae6bdeb7c1259012d28"
+checksum = "843a98750cd611cc2965a8213b53b43e715f13c37a9e096c6408e69990961db7"
 dependencies = [
 "libc",
 ]
@@ -960,7 +940,7 @@ checksum = "db5b29714e950dbb20d5e6f74f9dcec4edbcc1067bb7f8ed198c097b8c1a818b"
 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -1151,7 +1131,7 @@ dependencies = [
 "phf_shared",
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -1218,19 +1198,19 @@ dependencies = [

 [[package]]
 name = "prettyplease"
-version = "0.2.36"
+version = "0.2.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ff24dfcda44452b9816fff4cd4227e1bb73ff5a2f1bc1105aa92fb8565ce44d2"
+checksum = "479ca8adacdd7ce8f1fb39ce9ecccbfe93a3f1344b3d0d97f20bc0196208f62b"
 dependencies = [
 "proc-macro2",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
 name = "proc-macro2"
-version = "1.0.96"
+version = "1.0.101"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "beef09f85ae72cea1ef96ba6870c51e6382ebfa4f0e85b643459331f3daa5be0"
+checksum = "89ae43fd86e4158d6db51ad8e2b80f313af9cc74f5c0e03ccb87de09998732de"
 dependencies = [
 "unicode-ident",
 ]
@@ -1261,7 +1241,7 @@ dependencies = [
 "prost",
 "prost-types",
 "regex",
- "syn 2.0.104",
+ "syn 2.0.106",
 "tempfile",
 ]

@@ -1275,7 +1255,7 @@ dependencies = [
 "itertools 0.14.0",
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -1372,10 +1352,16 @@ dependencies = [
 ]

 [[package]]
-name = "rayon"
-version = "1.10.0"
+name = "rawzip"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b418a60154510ca1a002a752ca9714984e21e4241e804d32555251faf8b78ffa"
+checksum = "439c3cea2f04ab9cf078fab95c153af562df27cca8fbf88c0a7499c3f389ce23"
+
+[[package]]
+name = "rayon"
+version = "1.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "368f01d005bf8fd9b1206fb6fa653e6c4a81ceb1466406b81792d87c5677a58f"
 dependencies = [
 "either",
 "rayon-core",
@@ -1383,9 +1369,9 @@ dependencies = [

 [[package]]
 name = "rayon-core"
-version = "1.12.1"
+version = "1.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1465873a3dfdaa8ae7cb14b4383657caab0b3e8a0aa9ae8e04b044854c8dfce2"
+checksum = "22e18b0f0062d30d4230b2e85ff77fdfe4326feb054b9783a3460d8435c8ab91"
 dependencies = [
 "crossbeam-deque",
 "crossbeam-utils",
@@ -1527,7 +1513,7 @@ checksum = "5b0276cf7f2c73365f7157c8123c21cd9a50fbbd844757af28ca1f5925fc2a00"
 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -1586,12 +1572,6 @@ dependencies = [
 "rand_core",
 ]

-[[package]]
-name = "simd-adler32"
-version = "0.3.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d66dc143e6b11c1eddc06d5c423cfc97062865baf299914ab64caa38182078fe"
-
 [[package]]
 name = "siphasher"
 version = "1.0.1"
@@ -1651,9 +1631,9 @@ dependencies = [

 [[package]]
 name = "syn"
-version = "2.0.104"
+version = "2.0.106"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "17b6f705963418cdb9927482fa304bc562ece2fdd4f616084c50b7023b435a40"
+checksum = "ede7c438028d4436d71104916910f5bb611972c5cfd7f89b8300a8186e6fada6"
 dependencies = [
 "proc-macro2",
 "quote",
@@ -1682,35 +1662,35 @@ dependencies = [

 [[package]]
 name = "tempfile"
-version = "3.20.0"
+version = "3.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e8a64e3985349f2441a1a9ef0b853f869006c3855f2cda6862a94d26ebb9d6a1"
+checksum = "15b61f8f20e3a6f7e0649d825294eaf317edce30f82cf6026e7e4cb9222a7d1e"
 dependencies = [
 "fastrand",
 "getrandom 0.3.3",
 "once_cell",
 "rustix",
- "windows-sys 0.59.0",
+ "windows-sys 0.60.2",
 ]

 [[package]]
 name = "thiserror"
-version = "2.0.12"
+version = "2.0.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "567b8a2dae586314f7be2a752ec7474332959c6460e02bde30d702a66d488708"
+checksum = "3467d614147380f2e4e374161426ff399c91084acd2363eaf549172b3d5e60c0"
 dependencies = [
 "thiserror-impl",
 ]

 [[package]]
 name = "thiserror-impl"
-version = "2.0.12"
+version = "2.0.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f7cf42b4507d8ea322120659672cf1b9dbb93f8f2d4ecfd6e51350ff5b17a1d"
+checksum = "6c5e1be1c48b9172ee610da68fd9cd2770e7a4056cb3fc98710ee6906f0c7960"
 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -1740,7 +1720,7 @@ checksum = "2d2e76690929402faae40aebdda620a2c0e25dd6d3b9afe48867dfd95991f4bd"
 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -1754,9 +1734,9 @@ dependencies = [

 [[package]]
 name = "toml_edit"
-version = "0.23.3"
+version = "0.23.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "17d3b47e6b7a040216ae5302712c94d1cf88c95b47efa80e2c59ce96c878267e"
+checksum = "7211ff1b8f0d3adae1663b7da9ffe396eabe1ca25f0b0bee42b0da29a9ddce93"
 dependencies = [
 "indexmap",
 "serde",
@@ -1807,7 +1787,7 @@ checksum = "81383ab64e72a7a8b8e13130c49e3dab29def6d0c7d76a03087b3cf71c5c6903"
 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -2094,9 +2074,9 @@ checksum = "271414315aff87387382ec3d271b52d7ae78726f5d44ac98b4f4030c91880486"

 [[package]]
 name = "winnow"
-version = "0.7.12"
+version = "0.7.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f3edebf492c8125044983378ecb5766203ad3b4c2f7a922bd7dd207f6d443e95"
+checksum = "21a0236b59786fed61e2a80582dd500fe61f18b5dca67a4a067d0bc9039339cf"
 dependencies = [
 "memchr",
 ]
@@ -2126,7 +2106,7 @@ dependencies = [

 [[package]]
 name = "xtask"
-version = "3.20.0"
+version = "3.21.0"
 dependencies = [
 "anyhow",
 "clap",
@@ -2151,7 +2131,7 @@ checksum = "9ecf5b4cc5364572d7f4c329661bcc82724222973f2cab6f050a4e5c22f75181"
 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.104",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -2171,20 +2151,7 @@ checksum = "ce36e65b0d2999d2aafac989fb249189a141aee1f53c612c1f37d72631959f69"
 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.104",
-]
-
-[[package]]
-name = "zip"
-version = "4.1.0"
-source = "git+https://github.com/chenxiaolong/zip2?rev=59685f4dadbfee8cb3ea74c8fbb402b60d8137e8#59685f4dadbfee8cb3ea74c8fbb402b60d8137e8"
-dependencies = [
- "arbitrary",
- "crc32fast",
- "flate2",
- "indexmap",
- "memchr",
- "zopfli",
+ "syn 2.0.106",
 ]

 [[package]]
@@ -2192,15 +2159,3 @@ name = "zlib-rs"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "626bd9fa9734751fc50d6060752170984d7053f5a39061f524cda68023d4db8a"
-
-[[package]]
-name = "zopfli"
-version = "0.8.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "edfc5ee405f504cd4984ecc6f14d02d55cfda60fa4b689434ef4102aae150cd7"
-dependencies = [
- "bumpalo",
- "crc32fast",
- "log",
- "simd-adler32",
-]
@@ -4,7 +4,7 @@ members = ["avbroot", "e2e", "fuzz", "xtask"]
 resolver = "2"

 [workspace.package]
-version = "3.20.0"
+version = "3.21.0"
 license = "GPL-3.0-only"
 edition = "2024"
 repository = "https://github.com/chenxiaolong/avbroot"
@@ -51,7 +51,7 @@ avbroot applies the following patches to the partition images:

 3. Follow the steps to [generate signing keys](#generating-keys).

-    Skip this step if you're updating Android, Magisk, or KernelSU after you've performed an [initial setup](#initial-setup). [Updates](#updates) do not require signing keys since you have already generated them in the initial setup.
+    Skip this step if you're updating Android, Magisk, or KernelSU after you've already performed an [initial setup](#initial-setup). There's no need to generate new signing keys for [updates](#updates): any further updates must use the keys that were created during the initial setup.

 4. Patch the OTA zip. The base command is:

@@ -241,9 +241,9 @@ Updates to Android, Magisk, and KernelSU are all done the same way: by patching

 4. Sideload the patched OTA with `adb sideload`.

-5. Restart your phone. Note: the phone will likely take a long time to startup after an OS update (a few minutes in some cases).
+5. Restart your device. Note that the device will likely take longer than usual to start on the first boot after an OS update (a few minutes in some cases).

-**Warning**: Due to how virtual A/B works, there is a snapshot merge operation that Android runs invisibly in the background after installing an OTA and rebooting. During the snapshot merge process, it's not possible to sideload another OTA from recovery mode. Avoid doing anything that could result in a boot loop (eg. installing modules) until this process is complete because there is no way to recover, aside from unlocking the bootloader (and wiping) again.
+**WARNING**: Due to how virtual A/B works, there is a snapshot merge operation that Android runs invisibly in the background after installing an OTA and rebooting. During the snapshot merge process, it's not possible to sideload another OTA from recovery mode. Avoid doing anything that could result in a boot loop (eg. installing modules) until this process is complete because there is no way to recover, aside from unlocking the bootloader (and wiping) again.

 The status can be found by running `adb logcat -v color -s update_engine`. Alternatively, if [Custota](https://github.com/chenxiaolong/Custota) is installed (even if it's not configured to point to a custom OTA server), it will show a notification until the snapshot merge operation completes.

@@ -6,7 +6,7 @@ avbroot – это утилита для воспроизводимой моди

 ## Требования

-* Поддерживаются только устройства, использующие современную A/B-разметку. Это большинство девайсов, выпускаемых с Android 10 и новее (за исключением устройств от Samsung). Чтобы проверить, использует ли ваш телефон необходимую схему разметки, откройте zip-архив OTA и проверьте:
+* Поддерживаются только устройства, использующие современную A/B-разметку. Это большинство девайсов, выпускаемых с Android 10 и новее (за исключением устройств от Samsung). Чтобы проверить, использует ли ваше устройство необходимую схему разметки, откройте zip-архив OTA и проверьте:

  * наличие файла `payload.bin` (обычно находится в корне архива)
  * наличие файла `META-INF/com/android/metadata` (Android 10-11) или `META-INF/com/android/metadata.pb` (Android 12+)
@@ -49,6 +49,8 @@ avbroot модифицирует следующие образы:

 3. [Сгенерируйте ключи подписи.](#генерация-ключей)

+Пропустите этот шаг, если вы обновляете Android, Magisk или KernelSU уже после выполнения [первоначальной настройки](#первоначальная-настройка). Повторная генерация ключей подписи для [обновлений](#обновления) не требуется: для всех последующих обновлений должны использоваться те ключи, что были созданы при первоначальной настройке.
+
 4. Пропатчите ОТА-архив с помощью команды:

    ```bash
@@ -105,7 +107,7 @@ avbroot модифицирует следующие образы:

 Первые два компонента подписываются ключом AVB, а последние два – ключом OTA. Можно использовать один и тот же ключ, однако в следующих шагах описано, как сгенерировать два отдельных.

-Если вы патчите OTA сразу для нескольких устройств, настоятельно рекомендуется генерировать уникальные ключи для каждого девайса – так вы защитите себя от случайной прошивки неподходящего OTA для другого телефона.
+Если вы патчите OTA сразу для нескольких устройств, настоятельно рекомендуется генерировать уникальные ключи для каждого девайса – так вы защитите себя от случайной прошивки неподходящего OTA.

 1. Сгенерируйте ключи подписи для AVB и OTA.

@@ -209,6 +211,8 @@ avbroot совместим с любым стандартным 4096-битны
    init: [libfs_avb]Returning avb_handle with status: Success
    ```

+    Как ещё один вариант, Android-версию avbroot также можно использовать для [проверки разделов на устройстве](./README.extra.md#verifying-avb-hashes-and-signatures-on-device).
+
 9. Перезагрузитесь в fastboot и заблокируйте загрузчик. Это снова приведет к стиранию данных.

    ```bash
@@ -227,15 +231,19 @@ avbroot совместим с любым стандартным 4096-битны

 Обновления Android, Magisk и KernelSU выполняются одинаково – исключительно путем обновления или репатчинга того же самого OTA.

-1. Если Magisk или KernelSU обновились, сначала установите их новый `.apk`. Если вы случайно открыли приложение после обновления, убедитесь, что оно не начало прошивать загрузочный образ. Если появится предложение обновить сам загрузочный образ – отклоните его.
+1. Сгенерируйте новый пропатченный OTA согласно инструкции в разделе [использования.](#использование)

-2. Следуйте инструкции в разделе [использования,](#использование) чтобы пропатчить OTA уже с новым .apk Magisk'а/предварительно пропатченным образом с Magisk или KernelSU.
+2. Если обновляется Magisk или KernelSU, сначала установите их новый `.apk`. Если вы случайно открыли приложение, убедитесь, что оно **не начало** прошивать загрузочный образ. Если в самом приложении появится предложение обновить загрузочный образ, отклоните его.

 3. Перезагрузитесь в режим Recovery. Если устройство повисло на сплеше с сообщением "No command", удерживайте кнопку питания, а затем нажмите кнопку увеличения громкости один раз.

 4. Обновитесь (Apply update from adb → `adb sideload <ota.zip.patched>`).

-5. Готово!
+5. Перезагрузите устройство. Обратите внимание, что при первом запуске после обновления ОС устройство может загружаться дольше обычного (иногда до нескольких минут).
+
+**ПРЕДУПРЕЖДЕНИЕ**: В силу специфики работы виртуального A/B в Android, сразу после установки OTA и перезагрузки, в фоновом режиме незаметно запускается операция слияния снапшотов. Во время этого процесса невозможно установить другой OTA через режим Recovery. Пока продолжается слияние снапшотов, избегайте любых действий, которые могут привести к бутлупу (например, установка модулей), поскольку в случае сбоя восстановить устройство получится только повторно разблокировав загрузчик, стирая все данные.
+
+Узнать текущий статус процесса можно, выполнив команду: `adb logcat -v color -s update_engine`. Дополнительно, если установлено [Custota](https://github.com/chenxiaolong/Custota) (даже если оно не настроено на использование пользовательского OTA-сервера), приложение будет отображать соответствующее уведомление до завершения операции слияния снапшота.

 ## Возврат на заводскую прошивку

@@ -315,7 +323,7 @@ Magisk версии 25211 и новее требует наличие разде

    Теперь, когда имя раздела известно, его нужно указать avbroot с помощью команды `--magisk-preinit-device <имя>`. Имя раздела стоит запомнить или сохранить где-нибудь на будущее, оно вряд ли изменится при обновлении Magisk.

-Если запустить приложение Magisk на целевом устройстве невозможно (например, телефон не загружается), пропатчите OTA с аргументом `--ignore-magisk-warnings` и прошейте его. Затем выполните указанные выше шаги и повторно пропатчите OTA, но уже с указанием аргумента `--magisk-preinit-device <имя>`.
+Если запустить приложение Magisk на целевом устройстве невозможно (например, оно не загружается), пропатчите OTA с аргументом `--ignore-magisk-warnings` и прошейте его. Затем выполните указанные выше шаги и повторно пропатчите OTA, но уже с указанием аргумента `--magisk-preinit-device <имя>`.

 ## Проверка OTA

@@ -27,7 +27,7 @@ flate2 = { version = "1.0.29", features = ["zlib-rs"] }
 gf256 = { version = "0.3.0", features = ["rs"] }
 hex = { version = "0.4.3", features = ["serde"] }
 lz4_flex = "0.11.1"
-lzma-rust2 = "0.8.0"
+lzma-rust2 = "0.10.0"
 memchr = "2.6.0"
 num-bigint-dig = "0.8.4"
 num-traits = "0.2.16"
@@ -37,6 +37,7 @@ pkcs8 = { version = "0.10.2", features = ["encryption", "pem"] }
 prost = "0.14.1"
 # We can't upgrade to 0.9.0 until rsa updates its rand_core dependency.
 rand = "0.8.5"
+rawzip = "0.4.0"
 rayon = "1.7.0"
 regex = { version = "1.9.4", default-features = false, features = ["perf", "std"] }
 # We use ring instead of sha2 for sha256 digest computation of large files
@@ -58,15 +59,6 @@ x509-cert = { version = "0.2.4", features = ["builder"] }
 zerocopy = { version = "0.8.10", features = ["std"] }
 zerocopy-derive = "0.8.5"

-# https://github.com/zip-rs/zip2/pull/367
-# https://github.com/zip-rs/zip2/pull/368
-# For getting the data offset when writing new zip entries.
-[dependencies.zip]
-git = "https://github.com/chenxiaolong/zip2"
-rev = "59685f4dadbfee8cb3ea74c8fbb402b60d8137e8"
-default-features = false
-features = ["deflate"]
-
 [target.'cfg(unix)'.dependencies]
 libc = "0.2.158"
 rustix = { version = "1.0.3", default-features = false, features = ["process"] }
@@ -25,7 +25,7 @@ use crate::{
        self, AlgorithmType, AppendedDescriptorMut, AppendedDescriptorRef, Descriptor, Footer,
        HashTreeDescriptor, Header, KernelCmdlineDescriptor,
    },
-    stream::{self, PSeekFile, ReadFixedSizeExt, Reopen, ToWriter, check_cancel},
+    stream::{self, ReadFixedSizeExt, ToWriter, UserPosFile, check_cancel},
    util,
 };

@@ -52,7 +52,7 @@ fn read_avb_image(path: &Path) -> Result<(AvbInfo, BufReader<File>)> {
    Ok((info, reader))
 }

-fn write_avb_image(file: PSeekFile, info: &mut AvbInfo, recompute_size: bool) -> Result<()> {
+fn write_avb_image(file: &File, info: &mut AvbInfo, recompute_size: bool) -> Result<()> {
    let mut writer = BufWriter::new(file);

    info.image_size = if let Some(f) = &mut info.footer {
@@ -100,14 +100,13 @@ fn write_raw(
    reader: &mut BufReader<File>,
    size: u64,
    cancel_signal: &AtomicBool,
-) -> Result<PSeekFile> {
+) -> Result<File> {
    let file = fs::OpenOptions::new()
        .read(true)
        .write(true)
        .create(true)
        .truncate(true)
        .open(path)
-        .map(PSeekFile::new)
        .with_context(|| format!("Failed to open raw image for writing: {path:?}"))?;
    let mut writer = BufWriter::new(file);

@@ -132,7 +131,7 @@ fn write_raw_and_verify(
    info: &AvbInfo,
    ignore_invalid: bool,
    cancel_signal: &AtomicBool,
-) -> Result<PSeekFile> {
+) -> Result<File> {
    let f = info.footer.as_ref().expect("Not an appended image");

    let descriptor = info.header.appended_descriptor()?;
@@ -146,7 +145,7 @@ fn write_raw_and_verify(

    let raw_file = write_raw(path, reader, copy_size, cancel_signal)?;

-    let result = verify_and_repair(None, raw_file.reopen()?, descriptor, true, cancel_signal);
+    let result = verify_and_repair(None, &raw_file, descriptor, true, cancel_signal);

    // Chop off the old hash tree and FEC data.
    raw_file.set_len(f.original_image_size)?;
@@ -169,7 +168,7 @@ fn write_raw_and_update(
    reader: &mut BufReader<File>,
    info: &mut AvbInfo,
    cancel_signal: &AtomicBool,
-) -> Result<PSeekFile> {
+) -> Result<File> {
    assert!(info.footer.is_some(), "Not an appended image");

    let image_size = reader
@@ -181,7 +180,7 @@ fn write_raw_and_update(
    match info.header.appended_descriptor_mut()? {
        AppendedDescriptorMut::HashTree(d) => {
            d.image_size = image_size;
-            d.update(&raw_file, &raw_file, None, cancel_signal)
+            d.update(&raw_file, None, cancel_signal)
                .context("Failed to update hash tree descriptor")?;
        }
        AppendedDescriptorMut::Hash(d) => {
@@ -568,7 +567,7 @@ pub fn verify_headers(
 /// work.
 fn verify_and_repair(
    name: Option<&str>,
-    mut file: PSeekFile,
+    file: &File,
    descriptor: AppendedDescriptorRef,
    repair: bool,
    cancel_signal: &AtomicBool,
@@ -585,7 +584,7 @@ fn verify_and_repair(
                    warn!("Failed to verify hash tree descriptor{suffix}: {e}");
                    warn!("Attempting to repair using FEC data{suffix}");

-                    d.repair(&file, &file, cancel_signal)
+                    d.repair(&file, cancel_signal)
                        .with_context(|| format!("Failed to repair data{suffix}"))?;

                    d.verify(&file, cancel_signal).inspect(|()| {
@@ -599,8 +598,7 @@ fn verify_and_repair(
        AppendedDescriptorRef::Hash(d) => {
            info!("Verifying hash descriptor{suffix}");

-            file.rewind()?;
-            d.verify(file, cancel_signal)
+            d.verify(UserPosFile::new(file), cancel_signal)
                .with_context(|| format!("Failed to verify hash descriptor{suffix}"))?;
        }
    }
@@ -623,32 +621,28 @@ pub fn verify_descriptors(
    options.read(true);
    options.write(repair);

-    descriptors
-        .par_iter()
-        .map(|(name, descriptor)| {
-            let _span = parent_span.enter();
+    descriptors.par_iter().try_for_each(|(name, descriptor)| {
+        let _span = parent_span.enter();

-            let file = match opener.open(name, &options) {
-                Ok((_, f)) => PSeekFile::new(f),
-                // Some devices, like bluejay, have vbmeta descriptors that
-                // refer to partitions that exist on the device, but not in the
-                // OTA.
-                Err(e) if e.kind() == io::ErrorKind::NotFound && allow_missing => {
-                    warn!("{e}");
-                    return Ok(());
-                }
-                Err(e) => return Err(e.into()),
-            };
+        let file = match opener.open(name, &options) {
+            Ok((_, f)) => f,
+            // Some devices, like bluejay, have vbmeta descriptors that refer to
+            // partitions that exist on the device, but not in the OTA.
+            Err(e) if e.kind() == io::ErrorKind::NotFound && allow_missing => {
+                warn!("{e}");
+                return Ok(());
+            }
+            Err(e) => return Err(e.into()),
+        };

-            verify_and_repair(
-                Some(name),
-                file,
-                descriptor.try_into()?,
-                repair,
-                cancel_signal,
-            )
-        })
-        .collect()
+        verify_and_repair(
+            Some(name),
+            &file,
+            descriptor.try_into()?,
+            repair,
+            cancel_signal,
+        )
+    })
 }

 fn compute_digest_recursive(
@@ -772,13 +766,12 @@ fn pack_subcommand(cli: &PackCli, cancel_signal: &AtomicBool) -> Result<()> {
        file
    } else {
        File::create(&cli.output)
-            .map(PSeekFile::new)
            .with_context(|| format!("Failed to open output for writing: {:?}", cli.output))?
    };

    sign_or_clear(&mut info, &orig_header, &cli.key)?;

-    write_avb_image(file, &mut info, cli.recompute_size)?;
+    write_avb_image(&file, &mut info, cli.recompute_size)?;

    // We display the info at the very end after both the header and footer are
    // updated so that incorrect/incomplete information isn't shown.
@@ -801,7 +794,7 @@ fn repack_subcommand(cli: &RepackCli, cancel_signal: &AtomicBool) -> Result<()>
        // Write new hash tree and FEC data instead of copying the original.
        // There could have been errors in the original FEC data itself.
        if let AppendedDescriptorMut::HashTree(d) = info.header.appended_descriptor_mut()? {
-            d.update(&file, &file, None, cancel_signal)?;
+            d.update(&file, None, cancel_signal)?;
        }

        update_dm_verity_cmdline(&mut info)?;
@@ -809,13 +802,12 @@ fn repack_subcommand(cli: &RepackCli, cancel_signal: &AtomicBool) -> Result<()>
        file
    } else {
        File::create(&cli.output)
-            .map(PSeekFile::new)
            .with_context(|| format!("Failed to open for writing: {:?}", cli.output))?
    };

    sign_or_clear(&mut info, &orig_header, &cli.key)?;

-    write_avb_image(file, &mut info, false)?;
+    write_avb_image(&file, &mut info, false)?;

    // We display the info at the very end after both the header and footer are
    // updated so that incorrect/incomplete information isn't shown.
@@ -33,7 +33,7 @@ fn open_reader(
    path: &Path,
    include_trailer: bool,
 ) -> Result<(
-    CpioReader<CompressedReader<'_, BufReader<File>>>,
+    CpioReader<CompressedReader<BufReader<File>>>,
    CompressedFormat,
 )> {
    let file =
@@ -49,7 +49,7 @@ fn open_reader(
 fn open_writer(
    path: &Path,
    format: CompressedFormat,
-) -> Result<CpioWriter<CompressedWriter<'_, BufWriter<File>>>> {
+) -> Result<CpioWriter<CompressedWriter<BufWriter<File>>>> {
    let file =
        File::create(path).with_context(|| format!("Failed to open cpio for writing: {path:?}"))?;
    let writer = CompressedWriter::new(BufWriter::new(file), format)
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023 Andrew Gunnerson
+// SPDX-FileCopyrightText: 2023-2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{
@@ -13,15 +13,14 @@ use clap::{Parser, Subcommand};

 use crate::{
    format::fec::FecImage,
-    stream::{FromReader, PSeekFile, ToWriter},
+    stream::{FromReader, ToWriter},
 };

-fn open_input(path: &Path, rw: bool) -> Result<PSeekFile> {
+fn open_input(path: &Path, rw: bool) -> Result<File> {
    OpenOptions::new()
        .read(true)
        .write(rw)
        .open(path)
-        .map(PSeekFile::new)
        .with_context(|| format!("Failed to open file: {path:?}"))
 }

@@ -91,10 +90,7 @@ fn repair_subcommand(cli: &RepairCli, cancel_signal: &AtomicBool) -> Result<()>
    let input = open_input(&cli.input, true)?;
    let fec = read_fec(&cli.fec)?;

-    // The separate buffered readers and writers are safe because the function
-    // guarantees that every thread touches disjoint offsets and every offset is
-    // read and written at most once.
-    fec.repair(&input, &input, cancel_signal)
+    fec.repair(&input, cancel_signal)
        .context("Failed to repair file")?;

    Ok(())
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023 Andrew Gunnerson
+// SPDX-FileCopyrightText: 2023-2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{
@@ -13,15 +13,14 @@ use clap::{Parser, Subcommand};

 use crate::{
    format::hashtree::HashTreeImage,
-    stream::{FromReader, PSeekFile, ToWriter},
+    stream::{FromReader, ToWriter},
 };

-fn open_input(path: &Path, rw: bool) -> Result<PSeekFile> {
+fn open_input(path: &Path, rw: bool) -> Result<File> {
    OpenOptions::new()
        .read(true)
        .write(rw)
        .open(path)
-        .map(PSeekFile::new)
        .with_context(|| format!("Failed to open file: {path:?}"))
 }

@@ -16,37 +16,33 @@ use rayon::iter::{

 use crate::{
    format::lp::{Extent, ExtentType, ImageType, Metadata, SECTOR_SIZE},
-    stream::{self, FromReader, PSeekFile, Reopen, ToWriter},
+    stream::{self, FromReader, ToWriter, UserPosFile},
    util,
 };

-fn open_lp_inputs(paths: &[impl AsRef<Path>]) -> Result<(Vec<PSeekFile>, Metadata)> {
-    let mut inputs = paths
+fn open_lp_inputs(paths: &[impl AsRef<Path>]) -> Result<(Vec<File>, Metadata)> {
+    let inputs = paths
        .iter()
        .map(|p| {
            let p = p.as_ref();

-            File::open(p)
-                .map(PSeekFile::new)
-                .with_context(|| format!("Failed to open LP image for reading: {p:?}"))
+            File::open(p).with_context(|| format!("Failed to open LP image for reading: {p:?}"))
        })
        .collect::<Result<Vec<_>>>()?;

-    let metadata = Metadata::from_reader(&mut inputs[0])
+    let metadata = Metadata::from_reader(&inputs[0])
        .with_context(|| format!("Failed to parse LP image metadata: {:?}", paths[0].as_ref()))?;

    Ok((inputs, metadata))
 }

-fn open_lp_outputs(paths: &[impl AsRef<Path>]) -> Result<Vec<PSeekFile>> {
+fn open_lp_outputs(paths: &[impl AsRef<Path>]) -> Result<Vec<File>> {
    paths
        .iter()
        .map(|p| {
            let p = p.as_ref();

-            File::create(p)
-                .map(PSeekFile::new)
-                .with_context(|| format!("Failed to open LP image for writing: {p:?}"))
+            File::create(p).with_context(|| format!("Failed to open LP image for writing: {p:?}"))
        })
        .collect::<Result<Vec<_>>>()
 }
@@ -165,17 +161,15 @@ fn fill_slots(metadata: &mut Metadata) {
 }

 fn unpack_subcommand(lp_cli: &LpCli, cli: &UnpackCli, cancel_signal: &AtomicBool) -> Result<()> {
-    let mut inputs = cli
+    let inputs = cli
        .input
        .iter()
        .map(|p| {
-            File::open(p)
-                .map(PSeekFile::new)
-                .with_context(|| format!("Failed to open LP image for reading: {p:?}"))
+            File::open(p).with_context(|| format!("Failed to open LP image for reading: {p:?}"))
        })
        .collect::<Result<Vec<_>>>()?;

-    let mut metadata = Metadata::from_reader(&mut inputs[0])
+    let mut metadata = Metadata::from_reader(&inputs[0])
        .with_context(|| format!("Failed to read LP image metadata: {:?}", cli.input[0]))?;

    // Display and write only the selected slot.
@@ -216,7 +210,6 @@ fn unpack_subcommand(lp_cli: &LpCli, cli: &UnpackCli, cancel_signal: &AtomicBool
                util::path_join_single(&cli.output_images, format!("{}.img", partition.name))?;

            let file = File::create(&path)
-                .map(PSeekFile::new)
                .with_context(|| format!("Failed to open for writing: {path:?}"))?;

            file.set_len(partition.size()?)
@@ -247,10 +240,9 @@ fn unpack_subcommand(lp_cli: &LpCli, cli: &UnpackCli, cancel_signal: &AtomicBool
                .into_par_iter()
                .map(move |e| (g_index, p_index, e))
        })
-        .map(|(g_index, p_index, extent)| {
-            // Never fails for PSeekFiles.
-            let mut reader = inputs[extent.device_index].reopen()?;
-            let mut writer = files[g_index][p_index].reopen()?;
+        .try_for_each(|(g_index, p_index, extent)| {
+            let mut reader = UserPosFile::new(&inputs[extent.device_index]);
+            let mut writer = UserPosFile::new(&files[g_index][p_index]);

            let r_path = &cli.input[extent.device_index];
            let w_path = &paths[g_index][p_index];
@@ -267,9 +259,6 @@ fn unpack_subcommand(lp_cli: &LpCli, cli: &UnpackCli, cancel_signal: &AtomicBool

            Ok(())
        })
-        .collect::<Result<()>>()?;
-
-    Ok(())
 }

 fn pack_subcommand(lp_cli: &LpCli, cli: &PackCli, cancel_signal: &AtomicBool) -> Result<()> {
@@ -313,7 +302,6 @@ fn pack_subcommand(lp_cli: &LpCli, cli: &PackCli, cancel_signal: &AtomicBool) ->
                    util::path_join_single(&cli.input_images, format!("{}.img", partition.name))?;

                let mut file = File::open(&path)
-                    .map(PSeekFile::new)
                    .with_context(|| format!("Failed to open for reading: {path:?}"))?;

                let size = file
@@ -380,10 +368,9 @@ fn pack_subcommand(lp_cli: &LpCli, cli: &PackCli, cancel_signal: &AtomicBool) ->
                .into_par_iter()
                .map(move |e| (g_index, p_index, e))
        })
-        .map(|(g_index, p_index, extent)| {
-            // Never fails for PSeekFiles.
-            let mut reader = files[g_index][p_index].reopen()?;
-            let mut writer = outputs[extent.device_index].reopen()?;
+        .try_for_each(|(g_index, p_index, extent)| {
+            let mut reader = UserPosFile::new(&files[g_index][p_index]);
+            let mut writer = UserPosFile::new(&outputs[extent.device_index]);

            let r_path = &paths[g_index][p_index];
            let w_path = &cli.output[extent.device_index];
@@ -400,9 +387,6 @@ fn pack_subcommand(lp_cli: &LpCli, cli: &PackCli, cancel_signal: &AtomicBool) ->

            Ok(())
        })
-        .collect::<Result<()>>()?;
-
-    Ok(())
 }

 fn repack_subcommand(lp_cli: &LpCli, cli: &RepackCli, cancel_signal: &AtomicBool) -> Result<()> {
@@ -485,10 +469,9 @@ fn repack_subcommand(lp_cli: &LpCli, cli: &RepackCli, cancel_signal: &AtomicBool
        // Flatten extents in all partitions and split them to smaller chunks
        // for better parallelism.
        .flat_map(|partition| split_extents(&partition.extents))
-        .map(|extent| {
-            // Never fails for PSeekFiles.
-            let mut reader = inputs[extent.device_index].reopen()?;
-            let mut writer = outputs[extent.device_index].reopen()?;
+        .try_for_each(|extent| {
+            let mut reader = UserPosFile::new(&inputs[extent.device_index]);
+            let mut writer = UserPosFile::new(&outputs[extent.device_index]);

            let r_path = &cli.input[extent.device_index];
            let w_path = &cli.output[extent.device_index];
@@ -505,9 +488,6 @@ fn repack_subcommand(lp_cli: &LpCli, cli: &RepackCli, cancel_signal: &AtomicBool

            Ok(())
        })
-        .collect::<Result<()>>()?;
-
-    Ok(())
 }

 fn info_subcommand(lp_cli: &LpCli, cli: &InfoCli) -> Result<()> {
@@ -3,25 +3,28 @@

 use std::{
    borrow::Cow,
-    collections::{BTreeSet, HashMap, HashSet},
+    collections::{BTreeMap, BTreeSet, HashMap, HashSet},
    ffi::{OsStr, OsString},
    fs::{self, File},
-    io::{self, BufReader, BufWriter, Read, Seek, SeekFrom, Write},
+    io::{self, BufReader, Cursor, Read, Seek, SeekFrom, Write},
    ops::Range,
    path::{Path, PathBuf},
    str::FromStr,
-    sync::{Mutex, atomic::AtomicBool},
+    sync::{Arc, Mutex, atomic::AtomicBool},
 };

 use anyhow::{Context, Result, anyhow, bail};
 use bitflags::bitflags;
 use clap::{ArgAction, Args, Parser, Subcommand, value_parser};
+use rawzip::{
+    CompressionMethod, RECOMMENDED_BUFFER_SIZE, ZipArchive, ZipArchiveEntryWayfinder,
+    ZipArchiveWriter, extra_fields::ExtraFieldId,
+};
 use rayon::{iter::IntoParallelRefIterator, prelude::ParallelIterator};
 use tempfile::{NamedTempFile, TempDir};
 use topological_sort::TopologicalSort;
 use tracing::{debug_span, error, info, warn};
 use x509_cert::Certificate;
-use zip::{CompressionMethod, DateTime, ZipArchive, write::SimpleFileOptions};

 use crate::{
    cli::{
@@ -34,12 +37,14 @@ use crate::{
        ota::{self, SigningWriter, ZipEntry, ZipMode},
        padding,
        payload::{self, CowVersion, PayloadHeader, PayloadWriter, VabcAlgo, VabcParams},
-        zip::ZipWriterWrapper,
+        zip::{
+            self, ReaderAtWrapper, ZipArchiveReadAtExt, ZipEntriesSafeExt, ZipFileHeaderRecordExt,
+        },
    },
    patch::{
        boot::{
-            self, BootImagePatch, DsuPubKeyPatcher, MagiskRootPatcher, OtaCertPatcher,
-            PrepatchedImagePatcher,
+            self, BootImageOpener, BootImagePatch, DsuPubKeyPatcher, MagiskRootPatcher,
+            OtaCertPatcher, PrepatchedImagePatcher,
        },
        system,
    },
@@ -47,8 +52,8 @@ use crate::{
        build::tools::releasetools::OtaMetadata, chromeos_update_engine::DeltaArchiveManifest,
    },
    stream::{
-        self, CountingWriter, FromReader, HashingWriter, PSeekFile, ReadSeekReopen, Reopen,
-        SectionReader, SharedCursor, ToWriter, WriteSeekReopen,
+        self, FromReader, HashingWriter, MutexFile, ReadAt, ReadSeek, SectionReader,
+        SectionReaderAt, ToWriter, UserPosFile, WriteAt, WriteSeek,
    },
    util,
 };
@@ -122,7 +127,7 @@ enum InputFileState {
 }

 struct InputFile {
-    file: PSeekFile,
+    file: Arc<File>,
    state: InputFileState,
 }

@@ -131,7 +136,7 @@ struct InputFile {
 /// from the payload into a temporary file (that is unnamed if supported by the
 /// operating system).
 fn open_input_files(
-    payload: &(dyn ReadSeekReopen + Sync),
+    payload: &(dyn ReadAt + Sync),
    required_images: &HashMap<String, PartitionFlags>,
    external_images: &HashMap<String, PathBuf>,
    header: &PayloadHeader,
@@ -153,7 +158,7 @@ fn open_input_files(
            info!("Opening external image: {name}: {path:?}");

            let file = File::open(path)
-                .map(PSeekFile::new)
+                .map(Arc::new)
                .with_context(|| format!("Failed to open external image: {path:?}"))?;
            input_files.insert(
                name.clone(),
@@ -166,7 +171,7 @@ fn open_input_files(
            info!("Extracting from original payload: {name}");

            let file = tempfile::tempfile()
-                .map(PSeekFile::new)
+                .map(Arc::new)
                .with_context(|| format!("Failed to create temp file for: {name}"))?;

            payload::extract_image(payload, &file, header, name, cancel_signal)
@@ -195,7 +200,6 @@ fn patch_boot_images(
    key_avb: &RsaSigningKey,
    cancel_signal: &AtomicBool,
 ) -> Result<()> {
-    let input_files = Mutex::new(input_files);
    let boot_partitions = required_images
        .iter()
        .filter(|(_, flags)| flags.contains(PartitionFlags::BOOT))
@@ -207,19 +211,26 @@ fn patch_boot_images(
        util::join(util::sort(boot_partitions.iter()), ", "),
    );

+    struct Opener<'a>(Mutex<&'a mut HashMap<String, InputFile>>);
+
+    impl BootImageOpener for Opener<'_> {
+        fn open_original(&self, name: &str) -> io::Result<Box<dyn ReadSeek + Sync>> {
+            let locked = self.0.lock().unwrap();
+            Ok(Box::new(locked[name].file.clone()))
+        }
+
+        fn open_replacement(&self, name: &str) -> io::Result<Box<dyn WriteSeek + Sync>> {
+            let mut locked = self.0.lock().unwrap();
+            let input_file = locked.get_mut(name).unwrap();
+            input_file.file = tempfile::tempfile().map(Arc::new)?;
+            input_file.state = InputFileState::Modified;
+            Ok(Box::new(input_file.file.clone()))
+        }
+    }
+
    boot::patch_boot_images(
        &boot_partitions,
-        |name| {
-            let locked = input_files.lock().unwrap();
-            ReadSeekReopen::reopen_boxed(&locked[name].file)
-        },
-        |name| {
-            let mut locked = input_files.lock().unwrap();
-            let input_file = locked.get_mut(name).unwrap();
-            input_file.file = tempfile::tempfile().map(PSeekFile::new)?;
-            input_file.state = InputFileState::Modified;
-            WriteSeekReopen::reopen_boxed(&input_file.file)
-        },
+        &Opener(Mutex::new(input_files)),
        key_avb,
        boot_patchers,
        cancel_signal,
@@ -262,25 +273,19 @@ fn patch_system_image<'a>(

    // We can't modify external files in place.
    if input_file.state == InputFileState::External {
-        let mut reader = input_file.file.reopen()?;
+        let mut reader = UserPosFile::new(&input_file.file);
        let mut writer = tempfile::tempfile()
-            .map(PSeekFile::new)
            .with_context(|| format!("Failed to create temp file for: {target}"))?;

        stream::copy(&mut reader, &mut writer, cancel_signal)?;

-        input_file.file = writer;
+        input_file.file = Arc::new(writer);
        input_file.state = InputFileState::Extracted;
    }

-    let (mut ranges, other_ranges) = system::patch_system_image(
-        &input_file.file,
-        &input_file.file,
-        cert_ota,
-        key_avb,
-        cancel_signal,
-    )
-    .with_context(|| format!("Failed to patch system image: {target}"))?;
+    let (mut ranges, other_ranges) =
+        system::patch_system_image(&input_file.file, cert_ota, key_avb, cancel_signal)
+            .with_context(|| format!("Failed to patch system image: {target}"))?;

    input_file.state = InputFileState::Modified;

@@ -582,7 +587,16 @@ fn get_vabc_params(header: &PayloadHeader) -> Result<Option<VabcParams>> {

    let cow_version = match dpm.cow_version() {
        2 => CowVersion::V2,
-        3 => CowVersion::V3,
+        3 => {
+            let Some(compression_factor) = dpm.compression_factor else {
+                bail!("No CoW compression factor specified");
+            };
+            let Ok(compression_factor) = u32::try_from(compression_factor) else {
+                bail!("CoW compression factor is too large: {compression_factor}");
+            };
+
+            CowVersion::V3 { compression_factor }
+        }
        v => bail!("Unsupported CoW version: {v}"),
    };

@@ -591,18 +605,9 @@ fn get_vabc_params(header: &PayloadHeader) -> Result<Option<VabcParams>> {
        bail!("Unsupported VABC compression: {compression}");
    };

-    // This is unused by v2, but delta_generator sets it anyway.
-    let Some(compression_factor) = dpm.compression_factor else {
-        bail!("No CoW compression factor specified");
-    };
-    let Ok(compression_factor) = u32::try_from(compression_factor) else {
-        bail!("CoW compression factor is too large: {compression_factor}");
-    };
-
    let vabc_params = VabcParams {
        version: cow_version,
        algo: vabc_algo,
-        compression_factor,
    };

    Ok(Some(vabc_params))
@@ -700,7 +705,6 @@ fn update_vbmeta_headers(
                .with_context(|| format!("Failed to sign vbmeta header for image: {name}"))?;

            let mut writer = tempfile::tempfile()
-                .map(PSeekFile::new)
                .with_context(|| format!("Failed to create temp file for: {name}"))?;
            parent_header
                .to_writer(&mut writer)
@@ -710,7 +714,7 @@ fn update_vbmeta_headers(
                .with_context(|| format!("Failed to write vbmeta padding: {name}"))?;

            let input_file = images.get_mut(name).unwrap();
-            input_file.file = writer;
+            input_file.file = Arc::new(writer);
            input_file.state = InputFileState::Modified;
        }
    }
@@ -724,7 +728,7 @@ fn update_vbmeta_headers(
 /// scenario, unmodified chunks must be copied from the original payload.
 pub fn compress_image(
    name: &str,
-    file: &mut PSeekFile,
+    file: &mut Arc<File>,
    header: &mut PayloadHeader,
    ranges: Option<&[Range<u64>]>,
    cancel_signal: &AtomicBool,
@@ -733,9 +737,8 @@ pub fn compress_image(

    file.rewind()?;

-    let writer = tempfile::tempfile()
-        .map(PSeekFile::new)
-        .with_context(|| format!("Failed to create temp file for: {name}"))?;
+    let writer =
+        tempfile::tempfile().with_context(|| format!("Failed to create temp file for: {name}"))?;

    let vabc_params = get_vabc_params(header)?;
    let block_size = header.manifest.block_size();
@@ -791,10 +794,11 @@ pub fn compress_image(

                    partition.estimate_cow_size = Some(cow_estimate.size);
                    partition.estimate_op_count_max =
-                        (vabc_params.version == CowVersion::V3).then_some(cow_estimate.num_ops);
+                        matches!(vabc_params.version, CowVersion::V3 { .. })
+                            .then_some(cow_estimate.num_ops);
                }

-                *file = writer;
+                *file = Arc::new(writer);

                return Ok(indices);
            }
@@ -809,22 +813,16 @@ pub fn compress_image(

    info!("Compressing full image: {name}");

-    let (partition_info, operations, cow_estimate) = payload::compress_image(
-        &*file,
-        &writer,
-        name,
-        block_size,
-        vabc_params,
-        cancel_signal,
-    )?;
+    let (partition_info, operations, cow_estimate) =
+        payload::compress_image(file, &writer, name, block_size, vabc_params, cancel_signal)?;

    partition.new_partition_info = Some(partition_info);
    partition.operations = operations;
    partition.estimate_cow_size = cow_estimate.map(|e| e.size);
-    let is_v3 = vabc_params.is_some_and(|p| p.version == CowVersion::V3);
+    let is_v3 = vabc_params.is_some_and(|p| matches!(p.version, CowVersion::V3 { .. }));
    partition.estimate_op_count_max = cow_estimate.and_then(|e| is_v3.then_some(e.num_ops));

-    *file = writer;
+    *file = Arc::new(writer);

    #[allow(clippy::single_range_in_vec_init)]
    Ok(vec![0..partition.operations.len()])
@@ -834,13 +832,13 @@ pub fn compress_image(
 /// partition entry appropriately. The input file is not modified.
 fn recow_image(
    name: &str,
-    file: &mut PSeekFile,
+    file: &File,
    header: &mut PayloadHeader,
    cancel_signal: &AtomicBool,
 ) -> Result<()> {
    let _span = debug_span!("image", name).entered();

-    file.rewind()?;
+    (&*file).rewind()?;

    let vabc_params = get_vabc_params(header)?;
    let block_size = header.manifest.block_size();
@@ -862,7 +860,7 @@ fn recow_image(
    info!("Recomputing {} CoW size estimate: {name}", vabc_params.algo);

    let cow_estimate = payload::compute_cow_estimate(
-        &*file,
+        file,
        partition.operations.len() as u64,
        name,
        block_size,
@@ -872,14 +870,14 @@ fn recow_image(

    partition.estimate_cow_size = Some(cow_estimate.size);
    partition.estimate_op_count_max =
-        (vabc_params.version == CowVersion::V3).then_some(cow_estimate.num_ops);
+        matches!(vabc_params.version, CowVersion::V3 { .. }).then_some(cow_estimate.num_ops);

    Ok(())
 }

 #[allow(clippy::too_many_arguments)]
 fn patch_ota_payload(
-    payload: &(dyn ReadSeekReopen + Sync),
+    payload: &(dyn ReadAt + Sync),
    writer: impl Write,
    external_images: &HashMap<String, PathBuf>,
    boot_patchers: &[Box<dyn BootImagePatch + Sync>],
@@ -891,7 +889,7 @@ fn patch_ota_payload(
    cert_ota: &Certificate,
    cancel_signal: &AtomicBool,
 ) -> Result<(String, u64)> {
-    let mut header = PayloadHeader::from_reader(payload.reopen_boxed()?)
+    let mut header = PayloadHeader::from_reader(UserPosFile::new(payload))
        .context("Failed to load OTA payload header")?;
    if !header.is_full_ota() {
        bail!("Payload is a delta OTA, not a full OTA");
@@ -989,7 +987,7 @@ fn patch_ota_payload(
            f.state == InputFileState::Extracted && cow_images.contains(name.as_str())
        })
        .try_for_each(|(name, input_file)| {
-            recow_image(name, &mut input_file.file, &mut header, cancel_signal)
+            recow_image(name, &input_file.file, &mut header, cancel_signal)
        })?;

    // Drop all unmodified images. We only want to compress modified images.
@@ -1027,7 +1025,7 @@ fn patch_ota_payload(

    let mut payload_writer = PayloadWriter::new(writer, header.clone(), key_ota.clone())
        .context("Failed to write payload header")?;
-    let mut orig_payload_reader = payload.reopen_boxed().context("Failed to open payload")?;
+    let mut orig_payload_reader = UserPosFile::new(payload);

    while payload_writer
        .begin_next_operation()
@@ -1098,9 +1096,9 @@ fn patch_ota_payload(

 #[allow(clippy::too_many_arguments)]
 fn patch_ota_zip(
-    raw_reader: &PSeekFile,
-    zip_reader: &mut ZipArchive<impl Read + Seek>,
-    mut zip_writer: &mut ZipWriterWrapper<impl Write>,
+    raw_reader: &File,
+    zip_reader: &ZipArchive<ReaderAtWrapper<&File>>,
+    zip_writer: &mut ZipArchiveWriter<impl Write>,
    external_images: &HashMap<String, PathBuf>,
    boot_patchers: &[Box<dyn BootImagePatch + Sync>],
    skip_system_ota_cert: bool,
@@ -1112,22 +1110,50 @@ fn patch_ota_zip(
    cert_ota: &Certificate,
    cancel_signal: &AtomicBool,
 ) -> Result<(OtaMetadata, u64)> {
-    let mut missing = BTreeSet::from([ota::PATH_OTACERT, ota::PATH_PAYLOAD, ota::PATH_PROPERTIES]);
+    struct InputEntry {
+        compression_method: CompressionMethod,
+        is_zip64: bool,
+        // We can't store the rawzip::ZipEntry directly because of the lifetime
+        // generic parameter. We'll need to read the local headers again later.
+        wayfinder: ZipArchiveEntryWayfinder,
+    }

+    let mut missing = BTreeSet::from([ota::PATH_OTACERT, ota::PATH_PAYLOAD, ota::PATH_PROPERTIES]);
+    let mut buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+    let mut input_entries_iter = zip_reader.entries_safe(&mut buffer);
    // Keep in sorted order for reproducibility and to guarantee that the
    // payload is processed before its properties file.
-    let paths = zip_reader
-        .file_names()
-        .map(|p| p.to_owned())
-        .collect::<BTreeSet<_>>();
+    let mut input_entries = BTreeMap::new();

-    for path in &paths {
-        missing.remove(path.as_str());
+    while let Some((cd_entry, _)) = input_entries_iter
+        .next_entry()
+        .context("Failed to list zip entries")?
+    {
+        let path = cd_entry
+            .file_path_utf8()
+            .context("Zip contains non-UTF-8 paths")?;
+
+        missing.remove(path);
+
+        input_entries.insert(
+            path.to_owned(),
+            InputEntry {
+                compression_method: cd_entry.compression_method(),
+                // We only check for the sizes here instead of the presence of
+                // the ZIP64 extra field. The central header's extra fields may
+                // have ZIP64 only for the local header offset.
+                is_zip64: cd_entry.compressed_size_hint() >= 0xffffffff
+                    || cd_entry.uncompressed_size_hint() >= 0xffffffff,
+                wayfinder: cd_entry.wayfinder(),
+            },
+        );
    }

    if !missing.is_empty() {
        bail!("Missing entries in OTA zip: {}", util::join(missing, ", "));
-    } else if !paths.contains(ota::PATH_METADATA) && !paths.contains(ota::PATH_METADATA_PB) {
+    } else if !input_entries.contains_key(ota::PATH_METADATA)
+        && !input_entries.contains_key(ota::PATH_METADATA_PB)
+    {
        bail!(
            "Neither legacy nor protobuf OTA metadata files exist: {:?}, {:?}",
            ota::PATH_METADATA,
@@ -1138,26 +1164,16 @@ fn patch_ota_zip(
    let mut metadata = None;
    let mut properties = None;
    let mut payload_metadata_size = None;
-    let mut entries = vec![];
-    let mut last_entry_used_zip64 = false;
+    let mut metadata_entries = vec![];

-    for path in &paths {
+    for (path, input_entry) in &input_entries {
        let _span = debug_span!("zip", entry = path).entered();

-        let mut reader = zip_reader
-            .by_name(path)
+        let entry = zip_reader
+            .get_entry(input_entry.wayfinder)
+            .with_context(|| format!("Failed to open zip entry: {path}"))?;
+        let mut reader = zip::verifying_reader(&entry, input_entry.compression_method)
            .with_context(|| format!("Failed to open zip entry: {path}"))?;
-
-        // Android's libarchive parser is broken and only reads data descriptor
-        // size fields as 64-bit integers if the central directory says the file
-        // size is >= 2^32 - 1. We'll turn on zip64 if the input is above this
-        // threshold. This should be sufficient since the output file is likely
-        // to be larger.
-        let use_zip64 = reader.size() >= 0xffffffff;
-        let options = SimpleFileOptions::default()
-            .last_modified_time(DateTime::default())
-            .compression_method(CompressionMethod::Stored)
-            .large_file(use_zip64);

        // Processed at the end after all other entries are written.
        match path.as_str() {
@@ -1191,38 +1207,64 @@ fn patch_ota_zip(
            _ => {}
        }

-        // All remaining entries are written immediately.
-        let offset = zip_writer
-            .start_file(path, options)
-            .with_context(|| format!("Failed to begin new zip entry: {path}"))?;
-        let mut writer = CountingWriter::new(&mut zip_writer);
+        // Android's libziparchive parser is broken and only reads data
+        // descriptor size fields as 64-bit integers if the central directory
+        // says the file size is >= 2^32 - 1. APPNOTE 4.3.9.2 mentions that the
+        // parser should be reading 64-bit integers from the data descriptor if
+        // the ZIP64 extra field is present. Luckily, we don't have to do
+        // anything to work around this because rawzip's threshold when writing
+        // is the same as what libziparchive expects.
+        let mut builder = zip_writer
+            .new_file(path)
+            .compression_method(input_entry.compression_method);

+        if zip_mode == ZipMode::Seekable && input_entry.is_zip64 {
+            // We need to reserve space for the ZIP64 extra field when doing the
+            // post-processing to convert a streaming zip to a seekable one.
+            builder = builder.extra_field(
+                ExtraFieldId::ANDROID_ZIP_ALIGNMENT,
+                &[0u8; 16],
+                rawzip::Header::LOCAL,
+            )?;
+        }
+
+        let (entry_writer, data_config) = builder
+            .start()
+            .with_context(|| format!("Failed to begin new zip entry: {path}"))?;
+        let offset = entry_writer.stream_offset();
+        let compressed_writer =
+            zip::compressed_writer(entry_writer, input_entry.compression_method)
+                .with_context(|| format!("Failed to begin new zip entry: {path}"))?;
+        let mut data_writer = data_config.wrap(compressed_writer);
+
+        // All remaining entries are written immediately.
        match path.as_str() {
            ota::PATH_OTACERT => {
                // Use the user's certificate
                info!("Replacing zip entry: {path}");

-                crypto::write_pem_cert(Path::new(path), &mut writer, cert_ota)
+                crypto::write_pem_cert(Path::new(path), &mut data_writer, cert_ota)
                    .with_context(|| format!("Failed to write entry: {path}"))?;
            }
            ota::PATH_PAYLOAD => {
                info!("Patching zip entry: {path}");

-                if reader.compression() != CompressionMethod::Stored {
+                if input_entry.compression_method != CompressionMethod::Store {
                    bail!("{path} is not stored uncompressed");
                }

                // The zip library doesn't provide us with a seekable reader, so
                // we make our own from the underlying file.
-                let payload_reader = SectionReader::new(
-                    BufReader::new(raw_reader.reopen()?),
-                    reader.data_start(),
-                    reader.size(),
+                let payload_range = entry.compressed_data_range();
+                let payload_reader = SectionReaderAt::new(
+                    raw_reader,
+                    payload_range.0,
+                    payload_range.1 - payload_range.0,
                )?;

                let (p, m) = patch_ota_payload(
                    &payload_reader,
-                    &mut writer,
+                    &mut data_writer,
                    external_images,
                    boot_patchers,
                    skip_system_ota_cert,
@@ -1242,50 +1284,39 @@ fn patch_ota_zip(
                info!("Patching zip entry: {path}");

                // payload.bin is guaranteed to be patched first.
-                writer
+                data_writer
                    .write_all(properties.as_ref().unwrap().as_bytes())
                    .with_context(|| format!("Failed to write payload properties: {path}"))?;
            }
            _ => {
                info!("Copying zip entry: {path}");

-                stream::copy(&mut reader, &mut writer, cancel_signal)
+                stream::copy(&mut reader, &mut data_writer, cancel_signal)
                    .with_context(|| format!("Failed to copy zip entry: {path}"))?;
            }
        }

-        // Cannot fail.
-        let size = writer.stream_position()?;
+        let size = data_writer
+            .finish()
+            .and_then(|(w, d)| w.finish()?.finish(d))
+            .with_context(|| format!("Failed to finalize zip entry: {path}"))?;

-        entries.push(ZipEntry {
+        metadata_entries.push(ZipEntry {
            path: path.clone(),
            offset,
            size,
        });
-
-        last_entry_used_zip64 = use_zip64;
    }

    info!("Generating new OTA metadata");

-    let data_descriptor_size = match zip_mode {
-        ZipMode::Streaming => {
-            if last_entry_used_zip64 {
-                24
-            } else {
-                16
-            }
-        }
-        ZipMode::Seekable => 0,
-    };
    let metadata = ota::add_metadata(
-        &entries,
+        &metadata_entries,
        zip_writer,
        // Offset where next entry would begin.
-        entries.last().map(|e| e.offset + e.size).unwrap() + data_descriptor_size,
+        zip_writer.stream_offset(),
        &metadata.unwrap(),
        payload_metadata_size.unwrap(),
-        zip_mode,
    )
    .context("Failed to write new OTA metadata")?;

@@ -1293,7 +1324,7 @@ fn patch_ota_zip(
 }

 pub fn extract_payload(
-    raw_reader: &PSeekFile,
+    raw_reader: &File,
    directory: &Path,
    payload_offset: u64,
    payload_size: u64,
@@ -1309,26 +1340,24 @@ pub fn extract_payload(
        .map(|name| {
            let path = util::path_join_single(directory, format!("{name}.img"))?;
            let file = File::create(&path)
-                .map(PSeekFile::new)
+                .map(Arc::new)
                .with_context(|| format!("Failed to open for writing: {path:?}"))?;
            Ok((name.as_str(), file))
        })
        .collect::<Result<HashMap<_, _>>>()?;

-    let payload_reader = SectionReader::new(
-        BufReader::new(raw_reader.reopen()?),
-        payload_offset,
-        payload_size,
-    )?;
+    let payload_reader = SectionReaderAt::new(raw_reader, payload_offset, payload_size)?;

-    // Extract the images. Each time we're asked to open a new file, we just
-    // clone the relevant PSeekFile. We only ever have one actual kernel file
-    // descriptor for each file.
+    // Extract the images.
    payload::extract_images(
        &payload_reader,
-        |name| Ok(Box::new(BufWriter::new(output_files[name].reopen()?))),
+        images.iter().map(|n| {
+            (
+                n.as_str(),
+                &output_files[n.as_str()] as &(dyn WriteAt + Sync),
+            )
+        }),
        header,
-        images.iter().map(|n| n.as_str()),
        cancel_signal,
    )
    .context("Failed to extract images from payload")?;
@@ -1344,45 +1373,42 @@ fn verify_partition_hashes(
    images: &BTreeSet<String>,
    cancel_signal: &AtomicBool,
 ) -> Result<()> {
-    images
-        .par_iter()
-        .map(|name| -> Result<()> {
-            let partition = header
-                .manifest
-                .partitions
-                .iter()
-                .find(|p| p.partition_name == name.as_str())
-                .ok_or_else(|| anyhow!("Partition not found in header: {name}"))?;
-            let expected_digest = partition
-                .new_partition_info
-                .as_ref()
-                .and_then(|info| info.hash.as_ref())
-                .ok_or_else(|| anyhow!("Hash not found for partition: {name}"))?;
+    images.par_iter().try_for_each(|name| -> Result<()> {
+        let partition = header
+            .manifest
+            .partitions
+            .iter()
+            .find(|p| p.partition_name == name.as_str())
+            .ok_or_else(|| anyhow!("Partition not found in header: {name}"))?;
+        let expected_digest = partition
+            .new_partition_info
+            .as_ref()
+            .and_then(|info| info.hash.as_ref())
+            .ok_or_else(|| anyhow!("Hash not found for partition: {name}"))?;

-            let path = util::path_join_single(directory, format!("{name}.img"))?;
-            let file = File::open(&path)
-                .with_context(|| format!("Failed to open for reading: {path:?}"))?;
+        let path = util::path_join_single(directory, format!("{name}.img"))?;
+        let file =
+            File::open(&path).with_context(|| format!("Failed to open for reading: {path:?}"))?;

-            let mut writer = HashingWriter::new(
-                io::sink(),
-                ring::digest::Context::new(&ring::digest::SHA256),
+        let mut writer = HashingWriter::new(
+            io::sink(),
+            ring::digest::Context::new(&ring::digest::SHA256),
+        );
+
+        stream::copy(file, &mut writer, cancel_signal)?;
+
+        let digest = writer.finish().1.finish();
+
+        if digest.as_ref() != expected_digest {
+            bail!(
+                "Expected sha256 {}, but have {} for partition {name}",
+                hex::encode(expected_digest),
+                hex::encode(digest),
            );
+        }

-            stream::copy(file, &mut writer, cancel_signal)?;
-
-            let digest = writer.finish().1.finish();
-
-            if digest.as_ref() != expected_digest {
-                bail!(
-                    "Expected sha256 {}, but have {} for partition {name}",
-                    hex::encode(expected_digest),
-                    hex::encode(digest),
-                );
-            }
-
-            Ok(())
-        })
-        .collect()
+        Ok(())
+    })
 }

 pub fn patch_subcommand(cli: &PatchCli, cancel_signal: &AtomicBool) -> Result<()> {
@@ -1502,9 +1528,9 @@ pub fn patch_subcommand(cli: &PatchCli, cancel_signal: &AtomicBool) -> Result<()
    }

    let raw_reader = File::open(&cli.input)
-        .map(PSeekFile::new)
        .with_context(|| format!("Failed to open for reading: {:?}", cli.input))?;
-    let mut zip_reader = ZipArchive::new(BufReader::new(raw_reader.reopen()?))
+    let mut buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+    let zip_reader = ZipArchive::from_read_at(&raw_reader, &mut buffer)
        .with_context(|| format!("Failed to read zip: {:?}", cli.input))?;

    // Open the output file for reading too, so we can verify offsets later.
@@ -1516,20 +1542,15 @@ pub fn patch_subcommand(cli: &PatchCli, cancel_signal: &AtomicBool) -> Result<()
    )
    .context("Failed to open temporary output file")?;
    let temp_path = temp_writer.path().to_owned();
-    let mut zip_writer = match cli.zip_mode {
-        ZipMode::Streaming => {
-            let signing_writer = SigningWriter::new_streaming(temp_writer);
-            ZipWriterWrapper::new_streaming(signing_writer)
-        }
-        ZipMode::Seekable => {
-            let signing_writer = SigningWriter::new_seekable(temp_writer);
-            ZipWriterWrapper::new_seekable(signing_writer)
-        }
+    let signing_writer = match cli.zip_mode {
+        ZipMode::Streaming => SigningWriter::new_streaming(temp_writer),
+        ZipMode::Seekable => SigningWriter::new_seekable(temp_writer),
    };
+    let mut zip_writer = ZipArchiveWriter::new(signing_writer);

    let (metadata, payload_metadata_size) = patch_ota_zip(
        &raw_reader,
-        &mut zip_reader,
+        &zip_reader,
        &mut zip_writer,
        &external_images,
        &boot_patchers,
@@ -1598,27 +1619,49 @@ pub fn extract_subcommand(cli: &ExtractCli, cancel_signal: &AtomicBool) -> Resul
        warn!("Ignoring --boot-partition: deprecated and no longer needed");
    }

-    let mut raw_reader = File::open(&cli.input)
-        .map(PSeekFile::new)
+    let raw_reader = File::open(&cli.input)
        .with_context(|| format!("Failed to open for reading: {:?}", cli.input))?;
-    let mut zip = ZipArchive::new(BufReader::new(raw_reader.reopen()?))
+    let mut buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+    let zip = ZipArchive::from_read_at(&raw_reader, &mut buffer)
        .with_context(|| format!("Failed to read zip: {:?}", cli.input))?;
+
+    let mut entry_payload = None;
+    let mut entry_metadata_pb = None;
+
+    {
+        let mut entries = zip.entries_safe(&mut buffer);
+
+        while let Some((cd_entry, _)) =
+            entries.next_entry().context("Failed to list zip entries")?
+        {
+            let path = cd_entry
+                .file_path_utf8()
+                .context("Zip contains non-UTF-8 paths")?;
+
+            if path == ota::PATH_PAYLOAD {
+                entry_payload = Some((cd_entry.wayfinder(), cd_entry.compression_method()));
+            } else if path == ota::PATH_METADATA_PB {
+                entry_metadata_pb = Some((cd_entry.wayfinder(), cd_entry.compression_method()));
+            }
+        }
+    }
+
    let (payload_offset, payload_size) = {
+        let (wf, _) = entry_payload
+            .ok_or_else(|| anyhow!("Failed to find zip entry: {}", ota::PATH_PAYLOAD))?;
        let entry = zip
-            .by_name(ota::PATH_PAYLOAD)
+            .get_entry(wf)
            .with_context(|| format!("Failed to open zip entry: {}", ota::PATH_PAYLOAD))?;
-        (entry.data_start(), entry.size())
+        let range = entry.compressed_data_range();
+
+        (range.0, range.1 - range.0)
    };

    // Open the payload data directly.
-    let mut payload_reader = SectionReader::new(
-        BufReader::new(raw_reader.reopen()?),
-        payload_offset,
-        payload_size,
-    )
-    .context("Failed to directly open payload section")?;
+    let payload_reader = SectionReaderAt::new(&raw_reader, payload_offset, payload_size)
+        .context("Failed to directly open payload section")?;

-    let header = PayloadHeader::from_reader(&mut payload_reader)
+    let header = PayloadHeader::from_reader(UserPosFile::new(&payload_reader))
        .context("Failed to load OTA payload header")?;
    if !header.is_full_ota() {
        bail!("Payload is a delta OTA, not a full OTA");
@@ -1668,7 +1711,7 @@ pub fn extract_subcommand(cli: &ExtractCli, cancel_signal: &AtomicBool) -> Resul
    if let Some(path) = &cli.cert_ota {
        info!("Extracting embedded OTA certificate from zip signature");

-        let ota_sig = ota::parse_ota_sig(&mut raw_reader)?;
+        let ota_sig = ota::parse_ota_sig(&raw_reader)?;

        crypto::write_pem_cert_file(path, &ota_sig.cert)
            .with_context(|| format!("Failed to write OTA certificate: {path:?}"))?;
@@ -1677,14 +1720,13 @@ pub fn extract_subcommand(cli: &ExtractCli, cancel_signal: &AtomicBool) -> Resul
    if let Some(path) = &cli.public_key_avb {
        info!("Extracting AVB public key from vbmeta image");

-        let mut data = SharedCursor::new();
+        let data = MutexFile::new(Cursor::new(Vec::new()));

        payload::extract_image(&payload_reader, &data, &header, "vbmeta", cancel_signal)
            .context("Failed to extract vbmeta image")?;

-        data.rewind()?;
-
-        let (header, _, _) = avb::load_image(data).context("Failed to parse vbmeta image")?;
+        let (header, _, _) =
+            avb::load_image(UserPosFile::new(&data)).context("Failed to parse vbmeta image")?;

        fs::write(path, header.public_key)
            .with_context(|| format!("Failed to write AVB public key: {path:?}"))?;
@@ -1716,15 +1758,25 @@ pub fn extract_subcommand(cli: &ExtractCli, cancel_signal: &AtomicBool) -> Resul
        // flashall subcommand. We only add a basic device check to avoid
        // accidental flashes on the wrong device.

-        let mut metadata_entry = zip
-            .by_name(ota::PATH_METADATA_PB)
-            .with_context(|| format!("Failed to open zip entry: {:?}", ota::PATH_METADATA_PB))?;
-        let mut metadata_raw = vec![];
-        metadata_entry
-            .read_to_end(&mut metadata_raw)
-            .with_context(|| format!("Failed to read OTA metadata: {}", ota::PATH_METADATA_PB))?;
-        let metadata = ota::parse_protobuf_metadata(&metadata_raw)
-            .with_context(|| format!("Failed to parse OTA metadata: {}", ota::PATH_METADATA_PB))?;
+        let metadata = {
+            let (wf, cm) = entry_metadata_pb
+                .ok_or_else(|| anyhow!("Failed to find zip entry: {}", ota::PATH_METADATA_PB))?;
+            let mut metadata_reader = zip
+                .get_entry(wf)
+                .and_then(|e| zip::verifying_reader(&e, cm))
+                .with_context(|| format!("Failed to open zip entry: {}", ota::PATH_METADATA_PB))?;
+
+            let mut metadata_raw = vec![];
+            metadata_reader
+                .read_to_end(&mut metadata_raw)
+                .with_context(|| {
+                    format!("Failed to read OTA metadata: {}", ota::PATH_METADATA_PB)
+                })?;
+
+            ota::parse_protobuf_metadata(&metadata_raw).with_context(|| {
+                format!("Failed to parse OTA metadata: {}", ota::PATH_METADATA_PB)
+            })?
+        };

        let device = metadata
            .precondition
@@ -1860,7 +1912,6 @@ pub fn verify_subcommand(cli: &VerifyCli, cancel_signal: &AtomicBool) -> Result<
    }

    let raw_reader = File::open(&cli.input)
-        .map(PSeekFile::new)
        .with_context(|| format!("Failed to open for reading: {:?}", cli.input))?;
    let mut reader = BufReader::new(raw_reader);

@@ -1912,12 +1963,16 @@ pub fn verify_subcommand(cli: &VerifyCli, cancel_signal: &AtomicBool) -> Result<
        .find(|pf| pf.name() == ota::PATH_PAYLOAD)
        .ok_or_else(|| anyhow!("Missing property files entry: {}", ota::PATH_PAYLOAD))?;

-    let section_reader = SectionReader::new(&mut reader, pf_payload.offset, pf_payload.size)
+    let mut section_reader = SectionReader::new(&mut reader, pf_payload.offset, pf_payload.size)
        .context("Failed to directly open payload section")?;

-    if let Err(e) =
-        payload::verify_payload(section_reader, &ota_sig.cert, &properties, cancel_signal)
-            .context("Failed to verify payload signatures and digests")
+    if let Err(e) = payload::verify_payload(
+        &mut section_reader,
+        &ota_sig.cert,
+        &properties,
+        cancel_signal,
+    )
+    .context("Failed to verify payload signatures and digests")
    {
        fail_later!("{e:?}");
    }
@@ -1999,13 +2054,20 @@ pub fn verify_subcommand(cli: &VerifyCli, cancel_signal: &AtomicBool) -> Result<
        .filter(|(_, flags)| flags.contains(PartitionFlags::BOOT))
        .map(|(name, _)| name.as_str())
        .collect::<Vec<_>>();
-    let boot_images = boot::load_boot_images(&boot_image_names, |name| {
-        let path = util::path_join_single(temp_dir.path(), format!("{name}.img"))
-            .map_err(|e| io::Error::new(io::ErrorKind::InvalidInput, e))?;

-        Ok(Box::new(File::open(path).map(PSeekFile::new)?))
-    })
-    .context("Failed to load all boot images")?;
+    struct Opener<'a>(&'a Path);
+
+    impl BootImageOpener for Opener<'_> {
+        fn open_original(&self, name: &str) -> io::Result<Box<dyn ReadSeek + Sync>> {
+            let path = util::path_join_single(self.0, format!("{name}.img"))
+                .map_err(|e| io::Error::new(io::ErrorKind::InvalidInput, e))?;
+
+            Ok(Box::new(File::open(path)?))
+        }
+    }
+
+    let boot_images = boot::load_boot_images(&boot_image_names, &Opener(temp_dir.path()))
+        .context("Failed to load all boot images")?;
    let targets = OtaCertPatcher::new(ota_cert.clone())
        .find_targets(&boot_images, cancel_signal)
        .context("Failed to find boot image containing otacerts.zip")?;
@@ -7,7 +7,7 @@ use std::{
    fs::{self, File},
    io::{BufReader, BufWriter, Seek, SeekFrom},
    path::{Path, PathBuf},
-    sync::atomic::AtomicBool,
+    sync::{Arc, atomic::AtomicBool},
 };

 use anyhow::{Context, Result, anyhow, bail};
@@ -18,7 +18,7 @@ use crate::{
    cli::ota,
    crypto::{self, PassphraseSource, RsaSigningKey},
    format::payload::{PayloadHeader, PayloadWriter},
-    stream::{self, FromReader, PSeekFile},
+    stream::{self, FromReader},
    util,
 };

@@ -117,7 +117,7 @@ fn unpack_subcommand(
        .with_context(|| format!("Failed to create directory: {:?}", cli.output_images))?;

    ota::extract_payload(
-        &PSeekFile::new(reader.into_inner()),
+        &reader.into_inner(),
        &cli.output_images,
        0,
        payload_size,
@@ -153,7 +153,7 @@ fn pack_subcommand(
            let path =
                util::path_join_single(&cli.input_images, format!("{}.img", p.partition_name))?;
            let file = File::open(&path)
-                .map(PSeekFile::new)
+                .map(Arc::new)
                .with_context(|| format!("Failed to open file: {path:?}"))?;

            Ok((p.partition_name.clone(), file))
@@ -321,7 +321,7 @@ fn unpack_subcommand(
                let to_skip = i64::from(chunk.bounds.len()) * i64::from(metadata.header.block_size);

                writer
-                    .seek(SeekFrom::Current(to_skip))
+                    .seek_relative(to_skip)
                    .with_context(|| format!("Failed to seek file: {:?}", cli.output))?;
            }
            ChunkData::Crc32(_) => {}
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Andrew Gunnerson
+// SPDX-FileCopyrightText: 2023-2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{
@@ -29,8 +29,8 @@ use crate::{
        padding::{self, ZeroPadding},
    },
    stream::{
-        self, CountingReader, CountingWriter, FromReader, ReadFixedSizeExt, ReadSeekReopen,
-        ToWriter, WriteSeekReopen, WriteZerosExt,
+        self, CountingReader, CountingWriter, FromReader, ReadAt, ReadFixedSizeExt, ReadWriteAt,
+        ToWriter, UserPosFile, WriteZerosExt,
    },
    util::{self, OutOfBoundsError},
 };
@@ -149,10 +149,6 @@ pub enum Error {
    FecVerify(#[source] fec::Error),
    #[error("Failed to repair file with FEC data")]
    FecRepair(#[source] fec::Error),
-    #[error("Failed to reopen input file")]
-    InputReopen(#[source] io::Error),
-    #[error("Failed to reopen output file")]
-    OutputReopen(#[source] io::Error),
    #[error("Failed to compute hash of input file")]
    InputDigest(#[source] io::Error),
    #[error("Failed to read AVB data: {0}")]
@@ -510,10 +506,7 @@ impl HashTreeDescriptor {

    /// Update the root hash, hash tree, and FEC data. The hash tree and FEC
    /// data will be written immediately following the image data at offset
-    /// [`Self::image_size`]. Both `open_input` and `open_output` may be called
-    /// from multiple threads and must return independently seekable handles to
-    /// the same file. It is guaranteed that every thread will read and write
-    /// disjoint file offsets.
+    /// [`Self::image_size`].
    ///
    /// If `ranges` is [`Option::None`], then the hash tree and FEC data are
    /// updated for the whole while. Due to the nature of the file access
@@ -525,42 +518,37 @@ impl HashTreeDescriptor {
    /// that what is specified in order to perform the computations.
    ///
    /// The fields in this instance are updated atomically. No fields are
-    /// updated if an error occurs. The input file can be restored back to its
+    /// updated if an error occurs. The file can be restored back to its
    /// original state by truncating it to [`Self::image_size`].
    pub fn update(
        &mut self,
-        input: &(dyn ReadSeekReopen + Sync),
-        output: &(dyn WriteSeekReopen + Sync),
+        file: &(dyn ReadWriteAt + Sync),
        ranges: Option<&[Range<u64>]>,
        cancel_signal: &AtomicBool,
    ) -> Result<()> {
+        let mut pos_file = UserPosFile::new(file);
+
        let algorithm = digest_algorithm(&self.hash_algorithm)?;
        let hash_tree = HashTree::new(self.data_block_size, algorithm, &self.salt);
+        let tree_offset = self.image_size;
        let (root_digest, hash_tree_data) = match ranges {
            Some(r) => {
-                let mut reader = input.reopen_boxed().map_err(Error::InputReopen)?;
-                reader
-                    .seek(SeekFrom::Start(self.tree_offset))
+                pos_file
+                    .seek(SeekFrom::Start(tree_offset))
                    .map_err(|e| Error::DataRead("HashTree::tree_data", e))?;

-                let mut hash_tree_data = reader
+                let mut hash_tree_data = pos_file
                    .read_vec_exact(self.tree_size as usize)
                    .map_err(|e| Error::DataRead("HashTree::tree_data", e))?;

                let root_digest = hash_tree
-                    .update(
-                        input,
-                        self.image_size,
-                        r,
-                        &mut hash_tree_data,
-                        cancel_signal,
-                    )
+                    .update(file, self.image_size, r, &mut hash_tree_data, cancel_signal)
                    .map_err(Error::HashTreeUpdate)?;

                (root_digest, hash_tree_data)
            }
            None => hash_tree
-                .generate(input, self.image_size, cancel_signal)
+                .generate(file, self.image_size, cancel_signal)
                .map_err(Error::HashTreeGenerate)?,
        };

@@ -569,11 +557,10 @@ impl HashTreeDescriptor {

        let tree_size = hash_tree_data.len() as u64;

-        let mut writer = output.reopen_boxed().map_err(Error::OutputReopen)?;
-        writer
-            .seek(SeekFrom::Start(self.image_size))
+        pos_file
+            .seek(SeekFrom::Start(tree_offset))
            .map_err(|e| Error::DataWrite("HashTree::tree_data", e))?;
-        writer
+        pos_file
            .write_all(&hash_tree_data)
            .map_err(|e| Error::DataWrite("HashTree::tree_data", e))?;

@@ -588,58 +575,54 @@ impl HashTreeDescriptor {

            let parity: u8 = util::try_cast(self.fec_num_roots)
                .map_err(|e| Error::IntOutOfBounds("HashTree::fec_num_roots", e))?;
+            let fec_offset = tree_offset + tree_size;

            let fec_data = if let Some(r) = ranges {
                let mut r_with_hash_tree = r.to_vec();
-                r_with_hash_tree.push(self.tree_offset..self.tree_offset + tree_size);
+                r_with_hash_tree.push(tree_offset..tree_offset + tree_size);

                let (fec, fec_size) = self.get_fec()?;

-                let mut reader = input.reopen_boxed().map_err(Error::InputReopen)?;
-                reader
-                    .seek(SeekFrom::Start(self.fec_offset))
+                pos_file
+                    .seek(SeekFrom::Start(fec_offset))
                    .map_err(|e| Error::DataRead("HashTree::fec_data", e))?;

-                let mut fec_data = reader
+                let mut fec_data = pos_file
                    .read_vec_exact(fec_size)
                    .map_err(|e| Error::DataRead("HashTree::fec_data", e))?;

-                fec.update(input, &r_with_hash_tree, &mut fec_data, cancel_signal)
+                fec.update(file, &r_with_hash_tree, &mut fec_data, cancel_signal)
                    .map_err(Error::FecUpdate)?;

                fec_data
            } else {
                // The FEC covers the hash tree as well.
-                let fec = Fec::new(self.image_size + tree_size, self.data_block_size, parity)
-                    .map_err(Error::FecInit)?;
-                fec.generate(input, cancel_signal)
+                let fec =
+                    Fec::new(fec_offset, self.data_block_size, parity).map_err(Error::FecInit)?;
+                fec.generate(file, cancel_signal)
                    .map_err(Error::FecGenerate)?
            };

-            // Already seeked to FEC.
-            writer
+            pos_file
+                .seek(SeekFrom::Start(fec_offset))
+                .map_err(|e| Error::DataWrite("HashTree::fec_data", e))?;
+            pos_file
                .write_all(&fec_data)
                .map_err(|e| Error::DataWrite("HashTree::fec_data", e))?;

-            self.fec_offset = self.image_size + tree_size;
+            self.fec_offset = fec_offset;
            self.fec_size = fec_data.len() as u64;
        }

-        self.tree_offset = self.image_size;
+        self.tree_offset = tree_offset;
        self.tree_size = tree_size;
        self.root_digest = root_digest;

        Ok(())
    }

-    /// Verify the root hash, hash tree, and FEC data. `open_input` will be
-    /// called from multiple threads and must return independently seekable
-    /// handles to the same file.
-    pub fn verify(
-        &self,
-        input: &(dyn ReadSeekReopen + Sync),
-        cancel_signal: &AtomicBool,
-    ) -> Result<()> {
+    /// Verify the root hash, hash tree, and FEC data.
+    pub fn verify(&self, input: &(dyn ReadAt + Sync), cancel_signal: &AtomicBool) -> Result<()> {
        self.check_offsets()?;

        let algorithm = digest_algorithm(&self.hash_algorithm)?;
@@ -647,7 +630,7 @@ impl HashTreeDescriptor {
        util::check_bounds(self.tree_size, ..=HASH_TREE_MAX_SIZE)
            .map_err(|e| Error::IntOutOfBounds("HashTree::tree_size", e))?;

-        let mut reader = input.reopen_boxed().map_err(Error::InputReopen)?;
+        let mut reader = UserPosFile::new(input);
        reader
            .seek(SeekFrom::Start(self.tree_offset))
            .map_err(|e| Error::DataRead("HashTree::tree_data", e))?;
@@ -684,9 +667,7 @@ impl HashTreeDescriptor {
        Ok(())
    }

-    /// Try to repair errors in the input file using the FEC data. Both
-    /// `open_input` and `open_output` may be called from multiple threads and
-    /// must return independently seekable handles to the same file.
+    /// Try to repair errors in the input file using the FEC data.
    ///
    /// Due to the nature of FEC, when there are too many errors, it's possible
    /// for the data to be miscorrected to a "valid" state. [`Self::verify()`]
@@ -694,8 +675,7 @@ impl HashTreeDescriptor {
    /// actually valid.
    pub fn repair(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
-        output: &(dyn WriteSeekReopen + Sync),
+        file: &(dyn ReadWriteAt + Sync),
        cancel_signal: &AtomicBool,
    ) -> Result<()> {
        self.check_offsets()?;
@@ -705,7 +685,7 @@ impl HashTreeDescriptor {
            return Err(Error::FecMissing);
        }

-        let mut reader = input.reopen_boxed().map_err(Error::InputReopen)?;
+        let mut reader = UserPosFile::new(file);
        reader
            .seek(SeekFrom::Start(self.fec_offset))
            .map_err(|e| Error::DataRead("HashTree::fec_data", e))?;
@@ -717,7 +697,7 @@ impl HashTreeDescriptor {
            .read_vec_exact(fec_size)
            .map_err(|e| Error::DataRead("HashTree::fec_data", e))?;

-        fec.repair(input, output, &fec_data, cancel_signal)
+        fec.repair(file, &fec_data, cancel_signal)
            .map_err(Error::FecRepair)?;

        Ok(())
@@ -3,7 +3,11 @@

 use std::io::{self, Read, Seek, Write};

-use flate2::{Compression, read::GzDecoder, write::GzEncoder};
+use flate2::{
+    Compression,
+    read::{DeflateDecoder, GzDecoder},
+    write::{DeflateEncoder, GzEncoder},
+};
 use lz4_flex::frame::FrameDecoder;
 use lzma_rust2::{CheckType, XZOptions, XZReader, XZWriter};
 use serde::{Deserialize, Serialize};
@@ -105,19 +109,55 @@ impl<W: Write> Write for Lz4LegacyEncoder<W> {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize, Serialize)]
 pub enum CompressedFormat {
    None,
+    Deflate,
    Gzip,
    Lz4Legacy,
    Xz,
 }

-pub enum CompressedReader<'reader, R: Read> {
+pub enum CompressedReader<R: Read> {
    None(R),
+    /// Not autodetected.
+    Deflate(DeflateDecoder<R>),
    Gzip(GzDecoder<R>),
    Lz4(FrameDecoder<R>),
-    Xz(XZReader<'reader, R>),
+    /// Boxed because the [`XZReader`] is nearly 4 KiB.
+    Xz(Box<XZReader<R>>),
 }

-impl<'reader, R: Read + Seek + 'reader> CompressedReader<'reader, R> {
+impl<R: Read> CompressedReader<R> {
+    pub fn with_format(reader: R, format: CompressedFormat) -> Self {
+        match format {
+            CompressedFormat::None => Self::None(reader),
+            CompressedFormat::Deflate => Self::Deflate(DeflateDecoder::new(reader)),
+            CompressedFormat::Gzip => Self::Gzip(GzDecoder::new(reader)),
+            CompressedFormat::Lz4Legacy => Self::Lz4(FrameDecoder::new(reader)),
+            CompressedFormat::Xz => Self::Xz(Box::new(XZReader::new(reader, false))),
+        }
+    }
+
+    pub fn format(&self) -> CompressedFormat {
+        match self {
+            Self::None(_) => CompressedFormat::None,
+            Self::Deflate(_) => CompressedFormat::Deflate,
+            Self::Gzip(_) => CompressedFormat::Gzip,
+            Self::Lz4(_) => CompressedFormat::Lz4Legacy,
+            Self::Xz(_) => CompressedFormat::Xz,
+        }
+    }
+
+    pub fn into_inner(self) -> R {
+        match self {
+            Self::None(r) => r,
+            Self::Deflate(r) => r.into_inner(),
+            Self::Gzip(r) => r.into_inner(),
+            Self::Lz4(r) => r.into_inner(),
+            Self::Xz(r) => r.into_inner(),
+        }
+    }
+}
+
+impl<R: Read + Seek> CompressedReader<R> {
    pub fn new(mut reader: R, raw_if_unknown: bool) -> Result<Self> {
        let magic = reader.read_array_exact::<6>().map_err(Error::AutoDetect)?;

@@ -128,37 +168,20 @@ impl<'reader, R: Read + Seek + 'reader> CompressedReader<'reader, R> {
        } else if &magic[0..4] == LZ4_LEGACY_MAGIC {
            Ok(Self::Lz4(FrameDecoder::new(reader)))
        } else if &magic == XZ_MAGIC {
-            Ok(Self::Xz(XZReader::new(reader, false)))
+            Ok(Self::Xz(Box::new(XZReader::new(reader, false))))
        } else if raw_if_unknown {
            Ok(Self::None(reader))
        } else {
            Err(Error::UnknownFormat)
        }
    }
-
-    pub fn format(&self) -> CompressedFormat {
-        match self {
-            Self::None(_) => CompressedFormat::None,
-            Self::Gzip(_) => CompressedFormat::Gzip,
-            Self::Lz4(_) => CompressedFormat::Lz4Legacy,
-            Self::Xz(_) => CompressedFormat::Xz,
-        }
-    }
-
-    pub fn into_inner(self) -> R {
-        match self {
-            Self::None(r) => r,
-            Self::Gzip(r) => r.into_inner(),
-            Self::Lz4(r) => r.into_inner(),
-            Self::Xz(r) => r.into_inner(),
-        }
-    }
 }

-impl<'reader, R: Read + 'reader> Read for CompressedReader<'reader, R> {
+impl<R: Read> Read for CompressedReader<R> {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        match self {
            Self::None(r) => r.read(buf),
+            Self::Deflate(r) => r.read(buf),
            Self::Gzip(r) => r.read(buf),
            Self::Lz4(r) => r.read(buf),
            Self::Xz(r) => r.read(buf),
@@ -167,17 +190,22 @@ impl<'reader, R: Read + 'reader> Read for CompressedReader<'reader, R> {
 }

 #[allow(clippy::large_enum_variant)]
-pub enum CompressedWriter<'writer, W: Write> {
+pub enum CompressedWriter<W: Write> {
    None(W),
+    Deflate(DeflateEncoder<W>),
    Gzip(GzEncoder<W>),
    Lz4Legacy(Lz4LegacyEncoder<W>),
-    Xz(XZWriter<'writer, W>),
+    Xz(XZWriter<W>),
 }

-impl<'writer, W: Write + 'writer> CompressedWriter<'writer, W> {
+impl<W: Write> CompressedWriter<W> {
    pub fn new(writer: W, format: CompressedFormat) -> Result<Self> {
        match format {
            CompressedFormat::None => Ok(Self::None(writer)),
+            CompressedFormat::Deflate => Ok(Self::Deflate(DeflateEncoder::new(
+                writer,
+                Compression::default(),
+            ))),
            CompressedFormat::Gzip => {
                Ok(Self::Gzip(GzEncoder::new(writer, Compression::default())))
            }
@@ -199,6 +227,7 @@ impl<'writer, W: Write + 'writer> CompressedWriter<'writer, W> {
    pub fn format(&self) -> CompressedFormat {
        match self {
            Self::None(_) => CompressedFormat::None,
+            Self::Deflate(_) => CompressedFormat::Deflate,
            Self::Gzip(_) => CompressedFormat::Gzip,
            Self::Lz4Legacy(_) => CompressedFormat::Lz4Legacy,
            Self::Xz(_) => CompressedFormat::Xz,
@@ -208,6 +237,7 @@ impl<'writer, W: Write + 'writer> CompressedWriter<'writer, W> {
    pub fn finish(self) -> io::Result<W> {
        match self {
            Self::None(w) => Ok(w),
+            Self::Deflate(w) => w.finish(),
            Self::Gzip(w) => w.finish(),
            Self::Lz4Legacy(w) => w.finish(),
            Self::Xz(w) => w.finish(),
@@ -215,10 +245,11 @@ impl<'writer, W: Write + 'writer> CompressedWriter<'writer, W> {
    }
 }

-impl<'writer, W: Write + 'writer> Write for CompressedWriter<'writer, W> {
+impl<W: Write> Write for CompressedWriter<W> {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        match self {
            Self::None(w) => w.write(buf),
+            Self::Deflate(w) => w.write(buf),
            Self::Gzip(w) => w.write(buf),
            Self::Lz4Legacy(w) => w.write(buf),
            Self::Xz(w) => w.write(buf),
@@ -228,6 +259,7 @@ impl<'writer, W: Write + 'writer> Write for CompressedWriter<'writer, W> {
    fn flush(&mut self) -> io::Result<()> {
        match self {
            Self::None(w) => w.flush(),
+            Self::Deflate(w) => w.flush(),
            Self::Gzip(w) => w.flush(),
            Self::Lz4Legacy(w) => w.flush(),
            Self::Xz(w) => w.flush(),
@@ -89,12 +89,10 @@ impl fmt::Debug for RawHexU32 {
 impl From<u32> for RawHexU32 {
    fn from(mut value: u32) -> Self {
        let mut buf = [b'0'; 8];
-        let mut index = 7;

-        while value != 0 {
-            buf[index] = char::from_digit(value & 0xf, 16).unwrap() as u8;
+        for c in buf.iter_mut().rev() {
+            *c = char::from_digit(value & 0xf, 16).unwrap() as u8;
            value >>= 4;
-            index -= 1;
        }

        Self(buf)
@@ -1,10 +1,10 @@
-// SPDX-FileCopyrightText: 2023-2024 Andrew Gunnerson
+// SPDX-FileCopyrightText: 2023-2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{
    collections::HashSet,
    fmt,
-    io::{self, Read, Seek, SeekFrom, Write},
+    io::{self, Read, SeekFrom, Write},
    mem,
    ops::Range,
    sync::atomic::AtomicBool,
@@ -21,7 +21,10 @@ use zerocopy_derive::{FromBytes, Immutable, IntoBytes, KnownLayout, Unaligned};

 use crate::{
    format::verityrs,
-    stream::{self, FromReader, ReadSeekReopen, ToWriter, WriteSeekReopen, WriteZerosExt},
+    stream::{
+        self, FromReader, ReadAt, ReadSeek, ReadWriteAt, ReadWriteSeek, ToWriter, UserPosFile,
+        WriteSeek, WriteZerosExt,
+    },
    util::{self, NumBytes, OutOfBoundsError},
 };

@@ -68,10 +71,8 @@ pub enum Error {
    IntOutOfBounds(&'static str, #[source] OutOfBoundsError),
    #[error("{0:?} overflowed integer bounds during calculations")]
    IntOverflow(&'static str),
-    #[error("Failed to reopen input file")]
-    InputReopen(#[source] io::Error),
-    #[error("Failed to reopen output file")]
-    OutputReopen(#[source] io::Error),
+    #[error("Failed to get input file size")]
+    InputSize(#[source] io::Error),
    #[error("Failed to read FEC data: {0}")]
    DataRead(&'static str, #[source] io::Error),
    #[error("Failed to write FEC data: {0}")]
@@ -248,7 +249,7 @@ impl Fec {
    /// slice in the file offset grid.
    fn read_seq_block(
        &self,
-        mut reader: impl Read + Seek,
+        reader: &mut dyn ReadSeek,
        offset: u64,
        buf: &mut [u8],
    ) -> io::Result<()> {
@@ -276,7 +277,7 @@ impl Fec {
    /// slice in the file offset grid.
    fn write_seq_block(
        &self,
-        mut writer: impl Write + Seek,
+        writer: &mut dyn WriteSeek,
        offset: u64,
        buf: &[u8],
    ) -> io::Result<()> {
@@ -299,7 +300,7 @@ impl Fec {

    /// Read the nth round from the file. The data is laid out sequentially
    /// (row-by-row).
-    fn read_round(&self, mut reader: impl Read + Seek, round: u64) -> io::Result<Vec<u8>> {
+    fn read_round(&self, reader: &mut dyn ReadSeek, round: u64) -> io::Result<Vec<u8>> {
        let mut grid = vec![0u8; usize::from(self.rs_k) * self.block_size as usize];

        for row in 0..self.rs_k {
@@ -309,7 +310,7 @@ impl Fec {
            let row_end = row_start + self.block_size as usize;
            let row_slice = &mut grid[row_start..row_end];

-            self.read_seq_block(&mut reader, interleaved_offset, row_slice)?;
+            self.read_seq_block(reader, interleaved_offset, row_slice)?;
        }

        Ok(grid)
@@ -317,12 +318,7 @@ impl Fec {

    /// Write the nth round to the file. The data is expected to be laid out
    /// sequentially (row-by-row).
-    fn write_round(
-        &self,
-        mut writer: impl Write + Seek,
-        round: u64,
-        grid: &[u8],
-    ) -> io::Result<()> {
+    fn write_round(&self, writer: &mut dyn WriteSeek, round: u64, grid: &[u8]) -> io::Result<()> {
        for row in 0..self.rs_k {
            let interleaved_offset =
                round * u64::from(self.rs_k) * u64::from(self.block_size) + u64::from(row);
@@ -330,7 +326,7 @@ impl Fec {
            let row_end = row_start + self.block_size as usize;
            let row_slice = &grid[row_start..row_end];

-            self.write_seq_block(&mut writer, interleaved_offset, row_slice)?;
+            self.write_seq_block(writer, interleaved_offset, row_slice)?;
        }

        Ok(())
@@ -360,7 +356,7 @@ impl Fec {
    /// Generate FEC data for a single round.
    fn generate_one_round(
        &self,
-        reader: impl Read + Seek,
+        reader: &mut dyn ReadSeek,
        round: u64,
        fec: &mut [u8],
    ) -> Result<()> {
@@ -386,7 +382,7 @@ impl Fec {
    }

    /// Verify file data for a single round.
-    fn verify_one_round(&self, reader: impl Read + Seek, round: u64, fec: &[u8]) -> Result<()> {
+    fn verify_one_round(&self, reader: &mut dyn ReadSeek, round: u64, fec: &[u8]) -> Result<()> {
        assert_eq!(
            fec.len(),
            usize::from(self.parity()) * self.block_size as usize,
@@ -414,8 +410,7 @@ impl Fec {
    /// Repair file data for a single round.
    fn repair_one_round(
        &self,
-        reader: impl Read + Seek,
-        writer: impl Write + Seek,
+        file: &mut dyn ReadWriteSeek,
        round: u64,
        fec: &[u8],
    ) -> Result<u64> {
@@ -426,7 +421,7 @@ impl Fec {
        );

        let mut grid = self
-            .read_round(reader, round)
+            .read_round(file, round)
            .map_err(|e| Error::DataRead("round", e))?;
        let correct_errors = verityrs::FN_CORRECT_ERRORS[&self.rs_k];
        let parity = usize::from(self.parity());
@@ -445,7 +440,7 @@ impl Fec {
        }

        if num_corrected > 0 {
-            self.write_round(writer, round, &grid)
+            self.write_round(file, round, &grid)
                .map_err(|e| Error::DataWrite("round", e))?;
        }

@@ -458,7 +453,7 @@ impl Fec {
    /// This function is multithreaded and uses rayon's global thread pool.
    pub fn generate(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        cancel_signal: &AtomicBool,
    ) -> Result<Vec<u8>> {
        let fec_size = self.fec_size();
@@ -466,13 +461,12 @@ impl Fec {

        fec.par_chunks_exact_mut(fec_size / self.rounds as usize)
            .enumerate()
-            .map(|(round, buf)| -> Result<()> {
-                stream::check_cancel(cancel_signal).map_err(Error::InputReopen)?;
+            .try_for_each(|(round, buf)| -> Result<()> {
+                stream::check_cancel(cancel_signal).map_err(|e| Error::DataRead("(init)", e))?;

-                let reader = input.reopen_boxed().map_err(Error::InputReopen)?;
-                self.generate_one_round(reader, round as u64, buf)
-            })
-            .collect::<Result<()>>()?;
+                let mut reader = UserPosFile::new(input);
+                self.generate_one_round(&mut reader, round as u64, buf)
+            })?;

        Ok(fec)
    }
@@ -482,7 +476,7 @@ impl Fec {
    /// This function is multithreaded and uses rayon's global thread pool.
    pub fn update(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        ranges: &[Range<u64>],
        fec: &mut [u8],
        cancel_signal: &AtomicBool,
@@ -501,15 +495,12 @@ impl Fec {
        fec.par_chunks_exact_mut(fec_size / self.rounds as usize)
            .enumerate()
            .filter(|(round, _)| rounds_to_update.contains(&(*round as u64)))
-            .map(|(round, buf)| -> Result<()> {
-                stream::check_cancel(cancel_signal).map_err(Error::InputReopen)?;
+            .try_for_each(|(round, buf)| -> Result<()> {
+                stream::check_cancel(cancel_signal).map_err(|e| Error::DataRead("(init)", e))?;

-                let reader = input.reopen_boxed().map_err(Error::InputReopen)?;
-                self.generate_one_round(reader, round as u64, buf)
+                let mut reader = UserPosFile::new(input);
+                self.generate_one_round(&mut reader, round as u64, buf)
            })
-            .collect::<Result<()>>()?;
-
-        Ok(())
    }

    /// Verify that the file contains no errors. This is significantly faster
@@ -519,7 +510,7 @@ impl Fec {
    /// This function is multithreaded and uses rayon's global thread pool.
    pub fn verify(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        fec: &[u8],
        cancel_signal: &AtomicBool,
    ) -> Result<()> {
@@ -534,15 +525,12 @@ impl Fec {

        fec.par_chunks_exact(fec_size / self.rounds as usize)
            .enumerate()
-            .map(|(round, buf)| -> Result<()> {
-                stream::check_cancel(cancel_signal).map_err(Error::InputReopen)?;
+            .try_for_each(|(round, buf)| -> Result<()> {
+                stream::check_cancel(cancel_signal).map_err(|e| Error::DataRead("(init)", e))?;

-                let reader = input.reopen_boxed().map_err(Error::InputReopen)?;
-                self.verify_one_round(reader, round as u64, buf)
+                let mut reader = UserPosFile::new(input);
+                self.verify_one_round(&mut reader, round as u64, buf)
            })
-            .collect::<Result<()>>()?;
-
-        Ok(())
    }

    /// Repair the file. Up to `parity / 2` bytes per codeword can be repaired.
@@ -558,8 +546,7 @@ impl Fec {
    /// This function is multithreaded and uses rayon's global thread pool.
    pub fn repair(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
-        output: &(dyn WriteSeekReopen + Sync),
+        file: &(dyn ReadWriteAt + Sync),
        fec: &[u8],
        cancel_signal: &AtomicBool,
    ) -> Result<u64> {
@@ -576,15 +563,12 @@ impl Fec {
            .par_chunks_exact(fec_size / self.rounds as usize)
            .enumerate()
            .map(|(round, buf)| -> Result<u64> {
-                stream::check_cancel(cancel_signal).map_err(Error::InputReopen)?;
+                stream::check_cancel(cancel_signal).map_err(|e| Error::DataRead("(init)", e))?;

-                let reader = input.reopen_boxed().map_err(Error::InputReopen)?;
-                let writer = output.reopen_boxed().map_err(Error::OutputReopen)?;
-                self.repair_one_round(reader, writer, round as u64, buf)
+                let mut file = UserPosFile::new(file);
+                self.repair_one_round(&mut file, round as u64, buf)
            })
-            .collect::<Result<Vec<u64>>>()?
-            .into_iter()
-            .sum();
+            .try_reduce(|| 0, |prev, cur| Ok(prev + cur))?;

        Ok(num_corrected)
    }
@@ -636,14 +620,11 @@ impl FecImage {
    /// Generate FEC data for a file. `parity` is the number of parity bytes per
    /// 255-byte Reed-Solomon codeword.
    pub fn generate(
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        parity: u8,
        cancel_signal: &AtomicBool,
    ) -> Result<Self> {
-        let data_size = input
-            .reopen_boxed()
-            .and_then(|mut f| f.seek(SeekFrom::End(0)))
-            .map_err(Error::InputReopen)?;
+        let data_size = input.file_len().map_err(Error::InputSize)?;
        let fec = Fec::new(data_size, FEC_BLOCK_SIZE as u32, parity)?;
        let fec_data = fec.generate(input, cancel_signal)?;

@@ -657,7 +638,7 @@ impl FecImage {
    /// Update FEC data coreesponding to the specified file ranges.
    pub fn update(
        &mut self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        ranges: &[Range<u64>],
        cancel_signal: &AtomicBool,
    ) -> Result<()> {
@@ -667,11 +648,7 @@ impl FecImage {

    /// Check that a file contains no errors. This is significantly faster than
    /// [`Self::repair()`] if performing a repair is not necessary.
-    pub fn verify(
-        &self,
-        input: &(dyn ReadSeekReopen + Sync),
-        cancel_signal: &AtomicBool,
-    ) -> Result<()> {
+    pub fn verify(&self, input: &(dyn ReadAt + Sync), cancel_signal: &AtomicBool) -> Result<()> {
        let fec = Fec::new(self.data_size, FEC_BLOCK_SIZE as u32, self.parity)?;
        fec.verify(input, &self.fec, cancel_signal)
    }
@@ -687,18 +664,13 @@ impl FecImage {
    /// possible for there to be a false positive where the corrupted codeword
    /// is "corrected" into an incorrect value. FEC error detection is not a
    /// replacement for cryptographically secure digests.
-    ///
-    /// The inputs and outputs should point to the same underlying file because
-    /// only regions where errors are corrected are written. It is guaranteed
-    /// that multiple threads will always read and write disjoint file offsets.
    pub fn repair(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
-        output: &(dyn WriteSeekReopen + Sync),
+        file: &(dyn ReadWriteAt + Sync),
        cancel_signal: &AtomicBool,
    ) -> Result<u64> {
        let fec = Fec::new(self.data_size, FEC_BLOCK_SIZE as u32, self.parity)?;
-        fec.repair(input, output, &self.fec, cancel_signal)
+        fec.repair(file, &self.fec, cancel_signal)
    }

    /// Build one instance of the FEC header. The caller is responsible for
@@ -833,7 +805,7 @@ mod tests {
    use assert_matches::assert_matches;
    use rand::RngCore;

-    use crate::stream::SharedCursor;
+    use crate::stream::MutexFile;

    use super::*;

@@ -862,7 +834,7 @@ mod tests {
        );
    }

-    fn corrupt_byte(file: &mut SharedCursor, offset: u64) {
+    fn corrupt_byte(file: &mut UserPosFile<&MutexFile<Cursor<Vec<u8>>>>, offset: u64) {
        let mut buf = [0u8; 1];

        file.seek(SeekFrom::Start(offset)).unwrap();
@@ -881,11 +853,13 @@ mod tests {
        // Generate data big enough to span multiple rounds, but don't fill the
        // offset grid to ensure that the out-of-bounds-is-0 behavior works.
        let size = usize::from(rs_k) * block_size as usize * 3 - block_size as usize;
-        let mut file = SharedCursor::default();
+        let file = MutexFile::new(Cursor::new(Vec::new()));
+        let mut pos_file = UserPosFile::new(&file);
+
        let orig_digest = {
            let mut buf = vec![0u8; size];
            rand::thread_rng().fill_bytes(&mut buf);
-            file.write_all(&buf).unwrap();
+            pos_file.write_all(&buf).unwrap();
            ring::digest::digest(&ring::digest::SHA256, &buf)
        };

@@ -901,7 +875,7 @@ mod tests {
        fec.verify(&file, &fec_data, &cancel_signal).unwrap();

        // Verify that errors are detected.
-        corrupt_byte(&mut file, 0);
+        corrupt_byte(&mut pos_file, 0);
        assert_matches!(
            fec.verify(&file, &fec_data, &cancel_signal),
            Err(Error::HasErrors)
@@ -909,24 +883,24 @@ mod tests {

        // Corrupt one byte in every single codeword.
        for offset in 1..num_codewords {
-            corrupt_byte(&mut file, offset as u64);
+            corrupt_byte(&mut pos_file, offset as u64);
        }

        // Verify that all the single-byte errors can be fixed. We don't test
        // for Error::TooManyErrors because of the chance of false positives due
        // to the nature of RS.
-        fec.repair(&file, &file, &fec_data, &cancel_signal).unwrap();
+        fec.repair(&file, &fec_data, &cancel_signal).unwrap();

        let repaired_digest = {
            let mut buf = Vec::new();
-            file.rewind().unwrap();
-            file.read_to_end(&mut buf).unwrap();
+            pos_file.rewind().unwrap();
+            pos_file.read_to_end(&mut buf).unwrap();
            ring::digest::digest(&ring::digest::SHA256, &buf)
        };
        assert_eq!(repaired_digest.as_ref(), orig_digest.as_ref());

        // Intentionally update some data.
-        corrupt_byte(&mut file, 0);
+        corrupt_byte(&mut pos_file, 0);
        let mut fec_data_updated = fec_data.clone();
        let fec_data = fec.generate(&file, &cancel_signal).unwrap();
        fec.update(&file, &[0..1], &mut fec_data_updated, &cancel_signal)
@@ -948,11 +922,12 @@ mod tests {
    fn round_trip_image() {
        let cancel_signal = Arc::new(AtomicBool::new(false));

-        let mut file = SharedCursor::default();
+        let file = MutexFile::new(Cursor::new(Vec::new()));
+
        {
            let mut buf = [0u8; FEC_BLOCK_SIZE];
            rand::thread_rng().fill_bytes(&mut buf);
-            file.write_all(&buf).unwrap();
+            UserPosFile::new(&file).write_all(&buf).unwrap();
        }

        let image = FecImage::generate(&file, 2, &cancel_signal).unwrap();
@@ -3,7 +3,7 @@

 use std::{
    fmt,
-    io::{self, Cursor, Read, SeekFrom, Write},
+    io::{self, Cursor, Read, Seek, SeekFrom, Write},
    ops::Range,
    str,
    sync::atomic::AtomicBool,
@@ -24,7 +24,7 @@ use crate::{
        avb,
        padding::{self, ZeroPadding},
    },
-    stream::{self, FromReader, ReadFixedSizeExt, ReadSeekReopen, ToWriter},
+    stream::{self, FromReader, ReadAt, ReadFixedSizeExt, ToWriter, UserPosFile},
    util::{self, NumBytes, OutOfBoundsError},
 };

@@ -50,8 +50,8 @@ pub enum Error {
    IntOutOfBounds(&'static str, #[source] OutOfBoundsError),
    #[error("{0:?} overflowed integer bounds during calculations")]
    IntOverflow(&'static str),
-    #[error("Failed to reopen input file")]
-    InputReopen(#[source] io::Error),
+    #[error("Failed to get input file size")]
+    InputSize(#[source] io::Error),
    #[error("Failed to compute hash tree of input file")]
    InputDigest(#[source] io::Error),
    #[error("Failed to read hash tree data: {0}")]
@@ -189,7 +189,7 @@ impl HashTree {
    /// Hash one full level in parallel.
    fn hash_one_level_parallel(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        size: u64,
        level_data: &mut [u8],
        cancel_signal: &AtomicBool,
@@ -207,26 +207,23 @@ impl HashTree {
        level_data
            .par_chunks_mut(digest_size * multiplier as usize)
            .enumerate()
-            .map(|(chunk, out_data)| -> io::Result<()> {
+            .try_for_each(|(chunk, out_data)| -> io::Result<()> {
                let digests = out_data.len() / digest_size;
                let in_start = (chunk as u64) * multiplier * u64::from(self.block_size);
                let in_size = ((digests as u64) * u64::from(self.block_size)).min(size - in_start);

-                let mut reader = input.reopen_boxed()?;
+                let mut reader = UserPosFile::new(input);
                reader.seek(SeekFrom::Start(in_start))?;

                self.hash_partial_level(reader, in_size, out_data, cancel_signal)
            })
-            .collect::<io::Result<()>>()?;
-
-        Ok(())
    }

    /// Update parts of the hash tree level corresponding to the specified
    /// blocks.
    fn hash_partial_level_parallel(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        size: u64,
        block_ranges: &[Range<u64>],
        level_data: &mut [u8],
@@ -239,18 +236,15 @@ impl HashTree {
            .par_chunks_exact_mut(digest_size)
            .enumerate()
            .filter(|(chunk, _)| util::ranges_contains(block_ranges, &(*chunk as u64)))
-            .map(|(chunk, out_data)| -> io::Result<()> {
+            .try_for_each(|(chunk, out_data)| -> io::Result<()> {
                let in_start = (chunk as u64) * u64::from(self.block_size);
                let in_size = u64::from(self.block_size).min(size - in_start);

-                let mut reader = input.reopen_boxed()?;
+                let mut reader = UserPosFile::new(input);
                reader.seek(SeekFrom::Start(in_start))?;

                self.hash_partial_level(reader, in_size, out_data, cancel_signal)
            })
-            .collect::<io::Result<()>>()?;
-
-        Ok(())
    }

    /// Compute the hash tree and return the root digest. If `ranges` is
@@ -261,7 +255,7 @@ impl HashTree {
    /// offset of the leaf layer of the tree must equal `hash_tree_data`'s size.
    fn calculate(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        image_size: u64,
        ranges: Option<&[Range<u64>]>,
        level_offsets: &[Range<usize>],
@@ -270,7 +264,7 @@ impl HashTree {
    ) -> Result<Vec<u8>> {
        // Small files are hashed directly.
        if image_size <= u64::from(self.block_size) {
-            let mut reader = input.reopen_boxed().map_err(Error::InputReopen)?;
+            let mut reader = UserPosFile::new(input);
            let buf = reader
                .read_vec_exact(image_size as usize)
                .map_err(Error::InputDigest)?;
@@ -334,7 +328,7 @@ impl HashTree {
    /// hash tree data.
    pub fn generate(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        image_size: u64,
        cancel_signal: &AtomicBool,
    ) -> Result<(Vec<u8>, Vec<u8>)> {
@@ -358,7 +352,7 @@ impl HashTree {
    /// Returns the new root digest.
    pub fn update(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        image_size: u64,
        ranges: &[Range<u64>],
        hash_tree_data: &mut [u8],
@@ -387,7 +381,7 @@ impl HashTree {
    /// Verify that the file contains no errors.
    pub fn verify(
        &self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        image_size: u64,
        root_digest: &[u8],
        hash_tree_data: &[u8],
@@ -499,16 +493,13 @@ impl HashTreeImage {

    /// Generate hash tree data for a file.
    pub fn generate(
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        block_size: u32,
        algorithm: &str,
        salt: &[u8],
        cancel_signal: &AtomicBool,
    ) -> Result<Self> {
-        let image_size = input
-            .reopen_boxed()
-            .and_then(|mut f| f.seek(SeekFrom::End(0)))
-            .map_err(Error::InputReopen)?;
+        let image_size = input.file_len().map_err(Error::InputSize)?;
        let digest_algorithm = Self::digest_algorithm(algorithm)?;
        let hash_tree = HashTree::new(block_size, digest_algorithm, salt);
        let (root_digest, hash_tree_data) = hash_tree.generate(input, image_size, cancel_signal)?;
@@ -526,7 +517,7 @@ impl HashTreeImage {
    /// Update hash tree data coreesponding to the specified file ranges.
    pub fn update(
        &mut self,
-        input: &(dyn ReadSeekReopen + Sync),
+        input: &(dyn ReadAt + Sync),
        ranges: &[Range<u64>],
        cancel_signal: &AtomicBool,
    ) -> Result<()> {
@@ -545,11 +536,7 @@ impl HashTreeImage {
    }

    /// Check that a file contains no errors.
-    pub fn verify(
-        &self,
-        input: &(dyn ReadSeekReopen + Sync),
-        cancel_signal: &AtomicBool,
-    ) -> Result<()> {
+    pub fn verify(&self, input: &(dyn ReadAt + Sync), cancel_signal: &AtomicBool) -> Result<()> {
        let digest_algorithm = Self::digest_algorithm(&self.algorithm)?;
        let hash_tree = HashTree::new(self.block_size, digest_algorithm, &self.salt);

@@ -656,7 +643,7 @@ mod tests {

    use assert_matches::assert_matches;

-    use crate::stream::SharedCursor;
+    use crate::stream::MutexFile;

    use super::*;

@@ -697,7 +684,8 @@ mod tests {
    fn generate_update_verify() {
        let cancel_signal = AtomicBool::new(false);
        let hash_tree = HashTree::new(64, &ring::digest::SHA256, b"Salt");
-        let mut input = SharedCursor::new();
+        let input = MutexFile::new(Cursor::new(Vec::new()));
+        let mut pos_input = UserPosFile::new(&input);

        // Try input smaller than one block.
        let (root_digest, hash_tree_data) = hash_tree.generate(&input, 0, &cancel_signal).unwrap();
@@ -714,7 +702,7 @@ mod tests {

        // Try larger input that spans multiple blocks are results in an actual
        // hash tree being created.
-        input.write_all(&b"Data".repeat(25)).unwrap();
+        pos_input.write_all(&b"Data".repeat(25)).unwrap();

        let (root_digest, mut hash_tree_data) =
            hash_tree.generate(&input, 100, &cancel_signal).unwrap();
@@ -738,8 +726,8 @@ mod tests {
        );

        // Change some data and update the hash tree.
-        input.rewind().unwrap();
-        input.write_all(b"Changed").unwrap();
+        pos_input.rewind().unwrap();
+        pos_input.write_all(b"Changed").unwrap();

        let root_digest = hash_tree
            .update(&input, 100, &[0..7], &mut hash_tree_data, &cancel_signal)
@@ -775,8 +763,8 @@ mod tests {
            .unwrap();

        // But not if the data is corrupted.
-        input.rewind().unwrap();
-        input.write_all(b"Bad").unwrap();
+        pos_input.rewind().unwrap();
+        pos_input.write_all(b"Bad").unwrap();

        hash_tree
            .verify(&input, 100, &root_digest, &hash_tree_data, &cancel_signal)
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{
+    borrow::Cow,
    cmp::Ordering,
    collections::BTreeMap,
    fmt::{self, Write as _},
@@ -17,16 +18,16 @@ use cms::signed_data::SignedData;
 use const_oid::{ObjectIdentifier, db::rfc5912};
 use memchr::memmem;
 use prost::Message;
+use rawzip::{CompressionMethod, RECOMMENDED_BUFFER_SIZE, ZipArchive, ZipArchiveWriter};
 use ring::digest::{Algorithm, Context};
 use thiserror::Error;
 use x509_cert::{Certificate, der::Encode};
-use zip::{CompressionMethod, DateTime, ZipArchive, result::ZipError, write::SimpleFileOptions};

 use crate::{
    crypto::{self, RsaPublicKeyExt, RsaSigningKey, SignatureAlgorithm},
    format::{
        payload::{self, PayloadHeader},
-        zip::ZipWriterWrapper,
+        zip::{self, ZipEntriesSafeExt, ZipFileHeaderRecordExt},
    },
    protobuf::build::tools::releasetools::{OtaMetadata, ota_metadata::OtaType},
    stream::{self, FromReader, HashingReader, HashingWriter, ReadFixedSizeExt},
@@ -91,17 +92,21 @@ pub enum Error {
    #[error("Failed to decode OTA metadata protobuf message")]
    MetadataDecode(#[source] prost::DecodeError),
    #[error("Failed to open zip file")]
-    ZipOpen(#[source] ZipError),
+    ZipOpen(#[source] rawzip::Error),
+    #[error("Failed to list zip entries")]
+    ZipEntryList(#[source] rawzip::Error),
+    #[error("Missing zip entry: {0:?}")]
+    ZipEntryMissing(Cow<'static, str>),
    #[error("Failed to open zip entry: {0:?}")]
-    ZipEntryOpen(&'static str, #[source] ZipError),
+    ZipEntryOpen(Cow<'static, str>, #[source] rawzip::Error),
    #[error("Failed to start new zip entry: {0:?}")]
-    ZipEntryStart(&'static str, #[source] ZipError),
+    ZipEntryStart(Cow<'static, str>, #[source] rawzip::Error),
    #[error("Failed to read zip entry: {0:?}")]
-    ZipEntryRead(&'static str, #[source] io::Error),
+    ZipEntryRead(Cow<'static, str>, #[source] io::Error),
    #[error("Failed to write zip entry: {0:?}")]
-    ZipEntryWrite(&'static str, #[source] io::Error),
-    #[error("Failed to open zip entry #{0}")]
-    ZipIndexOpen(usize, #[source] ZipError),
+    ZipEntryWrite(Cow<'static, str>, #[source] io::Error),
+    #[error("Failed to finalize zip entry: {0:?}")]
+    ZipEntryFinish(Cow<'static, str>, #[source] rawzip::Error),
    #[error("Failed to load OTA certificate")]
    OtaCertLoad(#[source] crypto::Error),
    #[error("Failed to extract public key from OTA certificate")]
@@ -120,6 +125,8 @@ pub enum Error {
    DataRead(&'static str, #[source] io::Error),
    #[error("Failed to write OTA data: {0}")]
    DataWrite(&'static str, #[source] io::Error),
+    #[error("Failed to convert to non-streaming zip")]
+    MakeNonStreaming(#[source] rawzip::Error),
 }

 type Result<T> = std::result::Result<T, Error>;
@@ -500,16 +507,36 @@ impl fmt::Display for ZipMode {
 /// directory would start.
 pub fn add_metadata(
    zip_entries: &[ZipEntry],
-    zip_writer: &mut ZipWriterWrapper<impl Write>,
+    zip_writer: &mut ZipArchiveWriter<impl Write>,
    next_offset: u64,
    metadata: &OtaMetadata,
    payload_metadata_size: u64,
-    zip_mode: ZipMode,
 ) -> Result<OtaMetadata> {
+    fn write_entry(
+        archive: &mut ZipArchiveWriter<impl Write>,
+        path: &'static str,
+        data: &[u8],
+    ) -> Result<(u64, u64)> {
+        let (entry_writer, data_config) = archive
+            .new_file(path)
+            .start()
+            .map_err(|e| Error::ZipEntryStart(path.into(), e))?;
+        let data_offset = entry_writer.stream_offset();
+        let mut data_writer = data_config.wrap(entry_writer);
+
+        data_writer
+            .write_all(data)
+            .map_err(|e| Error::ZipEntryWrite(path.into(), e))?;
+
+        let data_size = data_writer
+            .finish()
+            .and_then(|(w, d)| w.finish(d))
+            .map_err(|e| Error::ZipEntryFinish(path.into(), e))?;
+
+        Ok((data_offset, data_size))
+    }
+
    let mut metadata = metadata.clone();
-    let options = SimpleFileOptions::default()
-        .last_modified_time(DateTime::default())
-        .compression_method(CompressionMethod::Stored);

    let mut prop_entries = zip_entries.iter().map(PropEntry::from).collect();
    add_payload_metadata_entry(&mut prop_entries, payload_metadata_size)?;
@@ -528,34 +555,25 @@ pub fn add_metadata(
    let (temp_legacy_offset, temp_modern_offset) = {
        let (legacy_raw, modern_raw) = serialize_metadata(&metadata);
        let raw_writer = Cursor::new(Vec::new());
-        let mut writer = match zip_mode {
-            ZipMode::Streaming => ZipWriterWrapper::new_streaming(raw_writer),
-            ZipMode::Seekable => ZipWriterWrapper::new_seekable(raw_writer),
-        };
+        // Note that we don't need to worry about the offsets changing based on
+        // the zip writing mode (streaming vs. seekable). Currently, we always
+        // include data descriptors and do post-processing to copy the fields
+        // into the local header without shifting the data.
+        let mut writer = ZipArchiveWriter::new(raw_writer);

-        let legacy_offset = writer
-            .start_file(PATH_METADATA, options)
-            .map_err(|e| Error::ZipEntryStart(PATH_METADATA, e))?;
-        writer
-            .write_all(legacy_raw.as_bytes())
-            .map_err(|e| Error::ZipEntryWrite(PATH_METADATA, e))?;
-
-        let modern_offset = writer
-            .start_file(PATH_METADATA_PB, options)
-            .map_err(|e| Error::ZipEntryStart(PATH_METADATA_PB, e))?;
-        writer
-            .write_all(&modern_raw)
-            .map_err(|e| Error::ZipEntryWrite(PATH_METADATA_PB, e))?;
+        let (legacy_offset, legacy_size) =
+            write_entry(&mut writer, PATH_METADATA, legacy_raw.as_bytes())?;
+        let (modern_offset, modern_size) = write_entry(&mut writer, PATH_METADATA_PB, &modern_raw)?;

        prop_entries.push(PropEntry::new(
            PATH_METADATA,
            next_offset + legacy_offset,
-            legacy_raw.len() as u64,
+            legacy_size,
        ));
        prop_entries.push(PropEntry::new(
            PATH_METADATA_PB,
            next_offset + modern_offset,
-            modern_raw.len() as u64,
+            modern_size,
        ));

        (next_offset + legacy_offset, next_offset + modern_offset)
@@ -570,19 +588,8 @@ pub fn add_metadata(
    {
        let (legacy_raw, modern_raw) = serialize_metadata(&metadata);

-        let legacy_offset = zip_writer
-            .start_file(PATH_METADATA, options)
-            .map_err(|e| Error::ZipEntryStart(PATH_METADATA, e))?;
-        zip_writer
-            .write_all(legacy_raw.as_bytes())
-            .map_err(|e| Error::ZipEntryWrite(PATH_METADATA, e))?;
-
-        let modern_offset = zip_writer
-            .start_file(PATH_METADATA_PB, options)
-            .map_err(|e| Error::ZipEntryStart(PATH_METADATA_PB, e))?;
-        zip_writer
-            .write_all(&modern_raw)
-            .map_err(|e| Error::ZipEntryWrite(PATH_METADATA_PB, e))?;
+        let (legacy_offset, _) = write_entry(zip_writer, PATH_METADATA, legacy_raw.as_bytes())?;
+        let (modern_offset, _) = write_entry(zip_writer, PATH_METADATA_PB, &modern_raw)?;

        assert_eq!(legacy_offset, temp_legacy_offset);
        assert_eq!(modern_offset, temp_modern_offset);
@@ -597,23 +604,24 @@ pub fn verify_metadata(
    metadata: &OtaMetadata,
    payload_metadata_size: u64,
 ) -> Result<()> {
-    let mut zip_reader = ZipArchive::new(reader).map_err(Error::ZipOpen)?;
+    let mut buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+    let archive = ZipArchive::from_seekable(reader, &mut buffer).map_err(Error::ZipOpen)?;
    let mut zip_entries = vec![];

-    for i in 0..zip_reader.len() {
-        let entry = zip_reader
-            .by_index(i)
-            .map_err(|e| Error::ZipIndexOpen(i, e))?;
+    let mut entries = archive.entries_safe(&mut buffer);

-        if entry.compression() != CompressionMethod::Stored {
+    while let Some((cd_entry, entry)) = entries.next_entry().map_err(Error::ZipEntryList)? {
+        if cd_entry.compression_method() != CompressionMethod::Store {
            continue;
        }

-        zip_entries.push(PropEntry::new(
-            entry.name(),
-            entry.data_start(),
-            entry.size(),
-        ));
+        let Ok(path) = cd_entry.file_path_utf8() else {
+            continue;
+        };
+
+        let range = entry.compressed_data_range();
+
+        zip_entries.push(PropEntry::new(path, range.0, range.1 - range.0));
    }

    add_payload_metadata_entry(&mut zip_entries, payload_metadata_size)?;
@@ -808,7 +816,7 @@ fn parse_raw_ota_sig(mut reader: impl Read + Seek) -> Result<RawOtaSignature> {
        .map_err(|e| Error::DataRead("file_size", e))?;

    reader
-        .seek(SeekFrom::Current(-6))
+        .seek_relative(-6)
        .map_err(|e| Error::DataRead("footer", e))?;
    let footer = reader
        .read_array_exact::<6>()
@@ -870,54 +878,73 @@ pub fn parse_ota_sig(reader: impl Read + Seek) -> Result<OtaSignature> {
 pub fn parse_zip_ota_info(
    reader: impl Read + Seek,
 ) -> Result<(OtaMetadata, Certificate, PayloadHeader, String)> {
-    let mut zip = ZipArchive::new(reader).map_err(Error::ZipOpen)?;
+    let mut buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+    let archive = ZipArchive::from_seekable(reader, &mut buffer).map_err(Error::ZipOpen)?;

-    let metadata = match zip.by_name(PATH_METADATA_PB) {
-        Ok(mut entry) => {
+    let mut metadata_modern = None;
+    let mut metadata_legacy = None;
+    let mut certificate = None;
+    let mut header = None;
+    let mut properties = None;
+
+    let mut entries = archive.entries_safe(&mut buffer);
+
+    while let Some((cd_entry, entry)) = entries.next_entry().map_err(Error::ZipEntryList)? {
+        let path = cd_entry.file_path_utf8().map_err(Error::ZipEntryList)?;
+
+        if path == PATH_METADATA_PB {
+            let mut reader = zip::verifying_reader(&entry, cd_entry.compression_method())
+                .map_err(|e| Error::ZipEntryOpen(PATH_METADATA_PB.into(), e))?;
            let mut buf = Vec::new();
-            entry
+
+            reader
                .read_to_end(&mut buf)
-                .map_err(|e| Error::ZipEntryRead(PATH_METADATA_PB, e))?;
-            parse_protobuf_metadata(&buf)?
-        }
-        e @ Err(ZipError::FileNotFound) => {
-            drop(e);
-            let mut entry = zip
-                .by_name(PATH_METADATA)
-                .map_err(|e| Error::ZipEntryOpen(PATH_METADATA, e))?;
+                .map_err(|e| Error::ZipEntryRead(PATH_METADATA_PB.into(), e))?;
+
+            metadata_modern = Some(parse_protobuf_metadata(&buf)?);
+        } else if path == PATH_METADATA {
+            let mut reader = zip::verifying_reader(&entry, cd_entry.compression_method())
+                .map_err(|e| Error::ZipEntryOpen(PATH_METADATA.into(), e))?;
            let mut buf = String::new();
-            entry
+
+            reader
                .read_to_string(&mut buf)
-                .map_err(|e| Error::ZipEntryRead(PATH_METADATA, e))?;
-            parse_legacy_metadata(&buf)?
+                .map_err(|e| Error::ZipEntryRead(PATH_METADATA.into(), e))?;
+
+            metadata_legacy = Some(parse_legacy_metadata(&buf)?);
+        } else if path == PATH_OTACERT {
+            let reader = zip::verifying_reader(&entry, cd_entry.compression_method())
+                .map_err(|e| Error::ZipEntryOpen(PATH_OTACERT.into(), e))?;
+
+            certificate = Some(
+                crypto::read_pem_cert(Path::new(PATH_OTACERT), reader)
+                    .map_err(Error::OtaCertLoad)?,
+            );
+        } else if path == PATH_PAYLOAD {
+            // No CRC validation because we only read the header.
+            let reader = zip::compressed_reader(&entry, cd_entry.compression_method())
+                .map_err(|e| Error::ZipEntryOpen(PATH_PAYLOAD.into(), e))?;
+
+            header = Some(PayloadHeader::from_reader(reader).map_err(Error::PayloadLoad)?);
+        } else if path == PATH_PROPERTIES {
+            let mut reader = zip::verifying_reader(&entry, cd_entry.compression_method())
+                .map_err(|e| Error::ZipEntryOpen(PATH_PROPERTIES.into(), e))?;
+            let mut buf = String::new();
+
+            reader
+                .read_to_string(&mut buf)
+                .map_err(|e| Error::ZipEntryRead(PATH_PROPERTIES.into(), e))?;
+
+            properties = Some(buf);
        }
-        Err(e) => return Err(Error::ZipEntryOpen(PATH_METADATA_PB, e)),
-    };
+    }

-    let certificate = {
-        let entry = zip
-            .by_name(PATH_OTACERT)
-            .map_err(|e| Error::ZipEntryOpen(PATH_OTACERT, e))?;
-        crypto::read_pem_cert(Path::new(PATH_OTACERT), entry).map_err(Error::OtaCertLoad)?
-    };
-
-    let header = {
-        let entry = zip
-            .by_name(PATH_PAYLOAD)
-            .map_err(|e| Error::ZipEntryOpen(PATH_PAYLOAD, e))?;
-        PayloadHeader::from_reader(entry).map_err(Error::PayloadLoad)?
-    };
-
-    let properties = {
-        let mut entry = zip
-            .by_name(PATH_PROPERTIES)
-            .map_err(|e| Error::ZipEntryOpen(PATH_PROPERTIES, e))?;
-        let mut buf = String::new();
-        entry
-            .read_to_string(&mut buf)
-            .map_err(|e| Error::ZipEntryRead(PATH_PROPERTIES, e))?;
-        buf
-    };
+    let metadata = metadata_modern
+        .or(metadata_legacy)
+        .ok_or_else(|| Error::ZipEntryMissing(PATH_METADATA_PB.into()))?;
+    let certificate = certificate.ok_or_else(|| Error::ZipEntryMissing(PATH_OTACERT.into()))?;
+    let header = header.ok_or_else(|| Error::ZipEntryMissing(PATH_PAYLOAD.into()))?;
+    let properties = properties.ok_or_else(|| Error::ZipEntryMissing(PATH_PROPERTIES.into()))?;

    Ok((metadata, certificate, header, properties))
 }
@@ -1077,6 +1104,11 @@ impl<W: Read + Write + Seek> SeekableSigningWriter<W> {
        cert: &Certificate,
        cancel_signal: &AtomicBool,
    ) -> Result<W> {
+        // We always write a streaming zip because that is what rawzip supports.
+        // Convert it to not be streaming. This will leave the data descriptors
+        // behind, but that is fine.
+        zip::make_non_streaming(&mut self.inner).map_err(Error::MakeNonStreaming)?;
+
        let file_size = self
            .seek(SeekFrom::End(0))
            .map_err(|e| Error::DataRead("file_size", e))?;
@@ -36,8 +36,8 @@ use crate::{
        install_operation::Type, signatures::Signature,
    },
    stream::{
-        self, CountingReader, FromReader, HashingReader, HashingWriter, ReadDiscardExt,
-        ReadFixedSizeExt, ReadSeekReopen, WriteSeek, WriteSeekReopen,
+        self, CountingReader, FromReader, HashingReader, HashingWriter, ReadAt, ReadDiscardExt,
+        ReadFixedSizeExt, ReadSeek, UserPosFile, WriteAt, WriteSeek,
    },
    util::{self, OutOfBoundsError},
 };
@@ -126,12 +126,8 @@ pub enum Error {
        num_blocks: u64,
        source: io::Error,
    },
-    #[error("Failed to reopen payload")]
-    PayloadReopen(#[source] io::Error),
-    #[error("Failed to open input file for partition: {0}")]
-    InputOpen(String, #[source] io::Error),
-    #[error("Failed to open output file for partition: {0}")]
-    OutputOpen(String, #[source] io::Error),
+    #[error("Failed to get input file size for partition: {0}")]
+    InputSize(String, #[source] io::Error),
    #[error("Failed to GZ compress partition image chunk")]
    GzCompress(#[source] io::Error),
    #[error("Failed to initialize XZ encoder")]
@@ -592,12 +588,12 @@ impl<W: Write> Write for PayloadWriter<W> {
 /// Verify the payload signatures using the specified certificate and check that
 /// the digests in `payload_properties.txt` are correct.
 pub fn verify_payload(
-    mut reader: impl Read + Seek,
+    reader: &mut dyn ReadSeek,
    cert: &Certificate,
    properties_raw: &str,
    cancel_signal: &AtomicBool,
 ) -> Result<()> {
-    let header = PayloadHeader::from_reader(&mut reader)?;
+    let header = PayloadHeader::from_reader(&mut *reader)?;
    reader.rewind().map_err(|e| Error::DataRead("header", e))?;

    let payload_signatures_offset = header
@@ -617,7 +613,7 @@ pub fn verify_payload(
    // Read from the beginning to the metadata signature.
    let metadata_size = header.blob_offset - u64::from(header.metadata_signature_size);
    stream::copy_n_inspect(
-        &mut reader,
+        &mut *reader,
        io::sink(),
        metadata_size,
        |data| {
@@ -634,7 +630,7 @@ pub fn verify_payload(
        let mut writer = Cursor::new(Vec::new());

        stream::copy_n_inspect(
-            &mut reader,
+            &mut *reader,
            &mut writer,
            header.metadata_signature_size.into(),
            |data| h_full.update(data),
@@ -664,7 +660,7 @@ pub fn verify_payload(

    // Read (and discard) all the payload blobs.
    stream::copy_n_inspect(
-        &mut reader,
+        &mut *reader,
        io::sink(),
        payload_signatures_offset,
        |data| {
@@ -692,7 +688,7 @@ pub fn verify_payload(
        let mut writer = Cursor::new(Vec::new());

        stream::copy_n_inspect(
-            &mut reader,
+            &mut *reader,
            &mut writer,
            payload_signatures_size,
            |data| h_full.update(data),
@@ -737,8 +733,8 @@ pub fn verify_payload(

 /// Apply a partition operation from `reader` to `writer`.
 pub fn apply_operation(
-    mut reader: impl Read + Seek,
-    mut writer: impl Write + Seek,
+    reader: &mut dyn ReadSeek,
+    writer: &mut dyn WriteSeek,
    block_size: u32,
    blob_offset: u64,
    op: &InstallOperation,
@@ -774,7 +770,7 @@ pub fn apply_operation(
            Type::Zero | Type::Discard => {
                stream::copy_n_inspect(
                    io::repeat(0),
-                    &mut writer,
+                    &mut *writer,
                    out_data_length,
                    |data| hasher.update(data),
                    cancel_signal,
@@ -793,8 +789,8 @@ pub fn apply_operation(
                match other {
                    Type::Replace => {
                        stream::copy_n_inspect(
-                            &mut reader,
-                            &mut writer,
+                            &mut *reader,
+                            &mut *writer,
                            data_length,
                            |data| hasher.update(data),
                            cancel_signal,
@@ -802,9 +798,9 @@ pub fn apply_operation(
                        .map_err(error_fn)?;
                    }
                    Type::ReplaceBz => {
-                        let mut decoder = BzDecoder::new(&mut writer);
+                        let mut decoder = BzDecoder::new(&mut *writer);
                        stream::copy_n_inspect(
-                            &mut reader,
+                            &mut *reader,
                            &mut decoder,
                            data_length,
                            |data| hasher.update(data),
@@ -816,10 +812,11 @@ pub fn apply_operation(
                    Type::ReplaceXz => {
                        // lzma_rust2 does not have a Write API, so we limit the
                        // reader and read till EOF.
-                        let limited_reader = (&mut reader).take(data_length);
+                        let limited_reader = (&mut *reader).take(data_length);
                        let hashing_reader = HashingReader::new(limited_reader, hasher);
                        let mut decoder = XZReader::new(hashing_reader, false);
-                        stream::copy(&mut decoder, &mut writer, cancel_signal).map_err(error_fn)?;
+                        stream::copy(&mut decoder, &mut *writer, cancel_signal)
+                            .map_err(error_fn)?;

                        (_, hasher) = decoder.into_inner().finish();
                    }
@@ -843,11 +840,10 @@ pub fn apply_operation(
 }

 /// Extract the specified image from the payload. This is done multithreaded and
-/// uses rayon's global thread pool. Both the `payload` and `output` streams
-/// will be reopened from multiple threads.
+/// uses rayon's global thread pool.
 pub fn extract_image(
-    payload: &(dyn ReadSeekReopen + Sync),
-    output: &(dyn WriteSeekReopen + Sync),
+    payload: &(dyn ReadAt + Sync),
+    output: &(dyn WriteAt + Sync),
    header: &PayloadHeader,
    partition_name: &str,
    cancel_signal: &AtomicBool,
@@ -859,40 +855,28 @@ pub fn extract_image(
        .find(|p| p.partition_name == partition_name)
        .ok_or_else(|| Error::MissingPartition(partition_name.to_owned()))?;

-    partition
-        .operations
-        .par_iter()
-        .map(|op| -> Result<()> {
-            let reader = payload.reopen_boxed().map_err(Error::PayloadReopen)?;
-            let writer = output
-                .reopen_boxed()
-                .map_err(|e| Error::OutputOpen(partition_name.to_owned(), e))?;
-
-            apply_operation(
-                reader,
-                writer,
-                header.manifest.block_size(),
-                header.blob_offset,
-                op,
-                cancel_signal,
-            )?;
-
-            Ok(())
-        })
-        .collect::<Result<_>>()
+    partition.operations.par_iter().try_for_each(|op| {
+        apply_operation(
+            &mut UserPosFile::new(payload),
+            &mut UserPosFile::new(output),
+            header.manifest.block_size(),
+            header.blob_offset,
+            op,
+            cancel_signal,
+        )
+    })
 }

 /// Extract the specified partition images from the payload into writers. This
-/// is done multithreaded and uses rayon's global thread pool. `open_payload`
-/// and `open_output` will be called from multiple threads.
-pub fn extract_images<'a>(
-    payload: &(dyn ReadSeekReopen + Sync),
-    open_output: impl Fn(&str) -> io::Result<Box<dyn WriteSeek>> + Sync,
+/// is done multithreaded and uses rayon's global thread pool.
+pub fn extract_images<'name, 'file>(
+    payload: &(dyn ReadAt + Sync),
+    outputs: impl IntoIterator<Item = (&'name str, &'file (dyn WriteAt + Sync))>,
    header: &PayloadHeader,
-    partition_names: impl IntoIterator<Item = &'a str>,
    cancel_signal: &AtomicBool,
 ) -> Result<()> {
-    let mut remaining = partition_names.into_iter().collect::<HashSet<_>>();
+    let outputs = outputs.into_iter().collect::<HashMap<_, _>>();
+    let mut remaining = outputs.keys().copied().collect::<HashSet<_>>();
    // We parallelize at the operation level or else one thread might get stuck
    // processing a giant image.
    let mut operations = vec![];
@@ -912,22 +896,19 @@ pub fn extract_images<'a>(

    operations
        .into_par_iter()
-        .map(|(name, op)| -> Result<()> {
-            let reader = payload.reopen_boxed().map_err(Error::PayloadReopen)?;
-            let writer = open_output(name).map_err(|e| Error::OutputOpen(name.to_owned(), e))?;
+        .try_for_each(|(name, op)| -> Result<()> {
+            let mut reader = UserPosFile::new(payload);
+            let mut writer = UserPosFile::new(&outputs[name]);

            apply_operation(
-                reader,
-                writer,
+                &mut reader,
+                &mut writer,
                header.manifest.block_size(),
                header.blob_offset,
                op,
                cancel_signal,
-            )?;
-
-            Ok(())
+            )
        })
-        .collect()
 }

 /// Compress raw data into a chunk to be used with a [`Type::ReplaceXz`]
@@ -959,10 +940,20 @@ fn compress_chunk(raw_data: &[u8], cancel_signal: &AtomicBool) -> Result<(Vec<u8
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Deserialize, Serialize)]
 pub enum CowVersion {
    V2,
-    V3,
+    V3 {
+        /// The maximum number of bytes to compress at a time.
+        compression_factor: u32,
+    },
 }

 impl CowVersion {
+    fn compression_factor(self) -> Option<u32> {
+        match self {
+            Self::V2 => None,
+            Self::V3 { compression_factor } => Some(compression_factor),
+        }
+    }
+
    /// Compute the size overhead required to store the headers and footers
    /// needed for this version of the on-disk CoW format.
    fn size_overhead(self, cow_replace_ops: u64, payload_install_ops: u64) -> u64 {
@@ -1012,7 +1003,7 @@ impl CowVersion {
                // AOSP: CowWriterV2::GetCowSizeInfo()
                overhead += SIZEOF_COW_FOOTER_V2;
            }
-            Self::V3 => {
+            Self::V3 { .. } => {
                // AOSP: CowWriterV3::OpenForWrite() -> GetDataOffset()
                overhead += SIZEOF_COW_HEADER_V3;
                overhead += BUFFER_REGION_DEFAULT_SIZE;
@@ -1229,8 +1220,6 @@ pub struct VabcParams {
    pub version: CowVersion,
    /// CoW compression algorithm.
    pub algo: VabcAlgo,
-    /// The maximum number of bytes to compress at a time.
-    pub compression_factor: u32,
 }

 /// Ensure that the partition size is aligned to the block size and that the
@@ -1239,17 +1228,16 @@ fn validate_partition_size(
    partition_name: &str,
    file_size: u64,
    block_size: u32,
-    compression_factor: u32,
+    compression_factor: Option<u32>,
 ) -> Result<()> {
    if block_size == 0 || !block_size.is_power_of_two() || CHUNK_SIZE % u64::from(block_size) != 0 {
        return Err(Error::InvalidBlockSize(block_size));
    }

-    if compression_factor == 0
-        || !compression_factor.is_power_of_two()
-        || CHUNK_SIZE % u64::from(compression_factor) != 0
+    if let Some(factor) = compression_factor
+        && (factor == 0 || !factor.is_power_of_two() || CHUNK_SIZE % u64::from(factor) != 0)
    {
-        return Err(Error::InvalidMaxCompressionChunkSize(compression_factor));
+        return Err(Error::InvalidMaxCompressionChunkSize(factor));
    }

    if file_size % u64::from(block_size) != 0 {
@@ -1270,7 +1258,7 @@ fn validate_partition_size(
 /// [`PartitionUpdate::estimate_op_count_max`] or else update_engine may fail to
 /// flash the partition due to running out of space on the CoW block device.
 pub fn compute_cow_estimate(
-    input: &(dyn ReadSeekReopen + Sync),
+    input: &(dyn ReadAt + Sync),
    payload_install_ops: u64,
    partition_name: &str,
    block_size: u32,
@@ -1278,24 +1266,24 @@ pub fn compute_cow_estimate(
    cancel_signal: &AtomicBool,
 ) -> Result<CowEstimate> {
    let file_size = input
-        .reopen_boxed()
-        .and_then(|mut r| r.seek(SeekFrom::End(0)))
-        .map_err(|e| Error::InputOpen(partition_name.to_owned(), e))?;
+        .file_len()
+        .map_err(|e| Error::InputSize(partition_name.to_owned(), e))?;
    let final_chunk_different = file_size % CHUNK_SIZE != 0;

    validate_partition_size(
        partition_name,
        file_size,
        block_size,
-        vabc_params.compression_factor,
+        vabc_params.version.compression_factor(),
    )?;

    let chunking = ChunkingParams {
        block_size,
        method: match vabc_params.version {
            CowVersion::V2 => ChunkingMethod::Exact,
-            CowVersion::V3 => {
-                ChunkingMethod::MaxPowerOf2(vabc_params.compression_factor.try_into().unwrap())
+            CowVersion::V3 { compression_factor } => {
+                // validate_partition_size() already validated that it is not 0.
+                ChunkingMethod::MaxPowerOf2(compression_factor.try_into().unwrap())
            }
        },
    };
@@ -1306,7 +1294,7 @@ pub fn compute_cow_estimate(
        .into_par_iter()
        .map(|chunk| -> Result<CowEstimate> {
            let data = (|| {
-                let mut reader = input.reopen_boxed()?;
+                let mut reader = UserPosFile::new(input);
                reader.seek(SeekFrom::Start(chunk * CHUNK_SIZE))?;

                let chunk_size = if final_chunk_different && chunk == chunks_total - 1 {
@@ -1353,8 +1341,8 @@ pub fn compute_cow_estimate(
 /// This is more efficient than separately calling [`compute_cow_estimate`]
 /// since the input does not need to be read twice.
 pub fn compress_image(
-    input: &(dyn ReadSeekReopen + Sync),
-    output: &(dyn WriteSeekReopen + Sync),
+    input: &(dyn ReadAt + Sync),
+    output: &(dyn WriteAt + Sync),
    partition_name: &str,
    block_size: u32,
    vabc_params: Option<VabcParams>,
@@ -1363,18 +1351,21 @@ pub fn compress_image(
    const CHUNK_GROUP: u64 = 32;

    let file_size = input
-        .reopen_boxed()
-        .and_then(|mut r| r.seek(SeekFrom::End(0)))
-        .map_err(|e| Error::InputOpen(partition_name.to_owned(), e))?;
+        .file_len()
+        .map_err(|e| Error::InputSize(partition_name.to_owned(), e))?;
    let final_chunk_different = file_size % CHUNK_SIZE != 0;

-    let compression_factor = vabc_params.map_or(block_size, |p| p.compression_factor);
-    validate_partition_size(partition_name, file_size, block_size, compression_factor)?;
+    validate_partition_size(
+        partition_name,
+        file_size,
+        block_size,
+        vabc_params.and_then(|p| p.version.compression_factor()),
+    )?;

    let chunking = ChunkingParams {
        block_size,
        method: match vabc_params.map(|p| p.version) {
-            Some(CowVersion::V3) => {
+            Some(CowVersion::V3 { compression_factor }) => {
                ChunkingMethod::MaxPowerOf2(compression_factor.try_into().unwrap())
            }
            _ => ChunkingMethod::Exact,
@@ -1397,7 +1388,7 @@ pub fn compress_image(
        let uncompressed_data_group = (chunks_done..chunks_done + chunks_group)
            .into_par_iter()
            .map(|chunk| -> io::Result<(u64, Vec<u8>)> {
-                let mut reader = input.reopen_boxed()?;
+                let mut reader = UserPosFile::new(input);
                let offset = reader.seek(SeekFrom::Start(chunk * CHUNK_SIZE))?;

                let chunk_size = if final_chunk_different && chunk == chunks_total - 1 {
@@ -1457,7 +1448,7 @@ pub fn compress_image(
        let group_operations = compressed_data_group
            .into_par_iter()
            .map(|(data, operation, _)| -> io::Result<InstallOperation> {
-                let mut writer = output.reopen_boxed()?;
+                let mut writer = UserPosFile::new(output);
                writer.seek(SeekFrom::Start(operation.data_offset.unwrap()))?;
                writer.write_all(&data)?;

@@ -1526,8 +1517,8 @@ fn extents_sorted(operations: &[InstallOperation]) -> bool {
 ///
 /// Returns the ranges of indices of `operations` that were updated.
 pub fn compress_modified_image(
-    input: &(dyn ReadSeekReopen + Sync),
-    output: &(dyn WriteSeekReopen + Sync),
+    input: &(dyn ReadAt + Sync),
+    output: &(dyn WriteAt + Sync),
    block_size: u32,
    partition_info: &mut PartitionInfo,
    operations: &mut [InstallOperation],
@@ -1576,7 +1567,7 @@ pub fn compress_modified_image(
                let extents_size: usize = util::try_cast(extents_size)
                    .map_err(|e| Error::IntOutOfBounds("extents_size", e))?;

-                let mut reader = input.reopen_boxed().map_err(Error::ChunkRead)?;
+                let mut reader = UserPosFile::new(input);
                reader
                    .seek(SeekFrom::Start(extents_start))
                    .map_err(Error::ChunkRead)?;
@@ -1623,7 +1614,7 @@ pub fn compress_modified_image(
        let modified_group_operations = compressed_data_group
            .into_par_iter()
            .map(|(data, i, operation)| {
-                let mut writer = output.reopen_boxed()?;
+                let mut writer = UserPosFile::new(output);
                writer.seek(SeekFrom::Start(operation.data_offset.unwrap()))?;
                writer.write_all(&data)?;

@@ -3,7 +3,7 @@

 use std::{
    fmt,
-    io::{self, Read, Seek, SeekFrom, Write},
+    io::{self, Read, Seek, Write},
    mem,
    ops::Range,
 };
@@ -672,7 +672,7 @@ fn hash_fill_chunk(
 /// A type for reading sparse files.
 pub struct SparseReader<R> {
    inner: R,
-    seek: Option<fn(&mut R, SeekFrom) -> io::Result<u64>>,
+    seek_relative: Option<fn(&mut R, i64) -> io::Result<()>>,
    header: RawHeader,
    /// Starting block for next chunk.
    block: u32,
@@ -689,7 +689,7 @@ impl<R: Read + Seek> SparseReader<R> {
    /// efficiently skipped without reading them.
    pub fn new_seekable(inner: R, crc_mode: CrcMode) -> Result<Self> {
        let mut result = Self::new(inner, crc_mode)?;
-        result.seek = Some(Seek::seek);
+        result.seek_relative = Some(Seek::seek_relative);
        Ok(result)
    }
 }
@@ -710,7 +710,7 @@ impl<R: Read> SparseReader<R> {

        Ok(Self {
            inner,
-            seek: None,
+            seek_relative: None,
            header,
            block: 0,
            chunk: 0,
@@ -744,12 +744,12 @@ impl<R: Read> SparseReader<R> {
    /// perform its own verification.
    pub fn next_chunk(&mut self) -> Result<Option<Chunk>> {
        if self.data_remain != 0 {
-            if let Some(seek) = self.seek {
+            if let Some(seek_relative) = self.seek_relative {
                if self.hasher.is_some() {
                    return Err(Error::Crc32RandomRead);
                }

-                seek(&mut self.inner, SeekFrom::Current(self.data_remain.into()))
+                seek_relative(&mut self.inner, self.data_remain.into())
                    .map_err(|e| Error::DataRead("data_remain", e))?;
                self.data_remain = 0;
            } else {
@@ -1026,7 +1026,7 @@ impl<W: Write> Write for SparseWriter<W> {

 #[cfg(test)]
 mod tests {
-    use super::{Chunk, ChunkBounds, ChunkData, ChunkList};
+    use super::*;

    #[test]
    fn chunk_list_merge() {
@@ -1,103 +1,516 @@
 // SPDX-FileCopyrightText: 2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

-use std::io::{self, Seek, SeekFrom, Write};
-
-use zip::{
-    ZipWriter,
-    result::ZipResult,
-    write::{FileOptionExtension, FileOptions, StreamWriter},
+use std::{
+    cmp::Ordering,
+    io::{self, Cursor, Read, Seek, SeekFrom, Write},
 };

-/// A wrapper around a seekable writer. `W` must implement [`Seek`], but only
-/// during the creation of a new instance. The resulting type can be stored in a
-/// parent container where the generic type does not implement [`Seek`].
-pub struct SeekWriter<W: Write> {
-    inner: W,
-    seek_fn: fn(&mut W, SeekFrom) -> io::Result<u64>,
+use bstr::ByteSlice;
+use rawzip::{
+    CompressionMethod, RECOMMENDED_BUFFER_SIZE, ReaderAt, ZipArchive, ZipEntries, ZipEntry,
+    ZipFileHeaderRecord, ZipLocator, ZipReader, ZipSliceArchive, ZipSliceEntries, ZipSliceEntry,
+    ZipSliceVerifier, ZipVerifier,
+    extra_fields::{ExtraFieldId, ExtraFields},
+};
+use zerocopy::{FromZeros, IntoBytes, little_endian};
+use zerocopy_derive::{FromBytes, Immutable, IntoBytes, KnownLayout, Unaligned};
+
+use crate::{
+    format::compression::{self, CompressedFormat, CompressedReader, CompressedWriter},
+    stream::ReadAt,
+};
+
+pub trait ZipFileHeaderRecordExt<'a> {
+    fn file_path_utf8(&self) -> Result<&'a str, rawzip::Error>;
 }

-impl<W: Write> SeekWriter<W> {
-    pub fn into_inner(self) -> W {
-        self.inner
+impl<'a> ZipFileHeaderRecordExt<'a> for ZipFileHeaderRecord<'a> {
+    fn file_path_utf8(&self) -> Result<&'a str, rawzip::Error> {
+        str::from_utf8(self.file_path().as_bytes())
+            .map_err(|e| rawzip::ErrorKind::InvalidUtf8(e).into())
    }
 }

-impl<W: Write + Seek> SeekWriter<W> {
-    pub fn new(inner: W) -> Self {
-        Self {
-            inner,
-            seek_fn: W::seek,
+/// Validate that the current entry's compressed data range does not overlap
+/// previously visited entries' ranges. This approach is identical to what
+/// rawzip recommends in their examples.
+fn validate_and_add_range(
+    compressed_ranges: &mut Vec<(u64, u64)>,
+    current_range: (u64, u64),
+    path: &[u8],
+) -> Result<(), rawzip::Error> {
+    let (current_start, current_end) = current_range;
+
+    let insert_pos = compressed_ranges
+        .binary_search_by_key(&current_start, |&(start, _)| start)
+        .unwrap_or_else(|pos| pos);
+
+    if insert_pos > 0 {
+        let (prev_start, prev_end) = compressed_ranges[insert_pos - 1];
+        if prev_end > current_start {
+            return Err(rawzip::ErrorKind::InvalidInput {
+                msg: format!("{:?} ({current_start}..{current_end}) overlaps previous range ({prev_start}..{prev_end})", path.as_bstr()),
+            }.into());
        }
    }
-}

-impl<W: Write> Write for SeekWriter<W> {
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        self.inner.write(buf)
+    if insert_pos < compressed_ranges.len() {
+        let (next_start, next_end) = compressed_ranges[insert_pos];
+        if current_end > next_start {
+            return Err(rawzip::ErrorKind::InvalidInput {
+                msg: format!("{:?} ({current_start}..{current_end}) overlaps next range ({next_start}..{next_end})", path.as_bstr()),
+            }.into());
+        }
    }

-    fn flush(&mut self) -> io::Result<()> {
-        self.inner.flush()
-    }
+    compressed_ranges.insert(insert_pos, current_range);
+
+    Ok(())
 }

-impl<W: Write> Seek for SeekWriter<W> {
-    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
-        (self.seek_fn)(&mut self.inner, pos)
-    }
-}
-
-/// This is an ugly hack to have a single type represent both seekable and
-/// streaming [`ZipWriter`]s. `W` only needs to implement [`Seek`] when creating
-/// a seekable instance via [`Self::new_seekable`].
-pub enum ZipWriterWrapper<W: Write> {
-    Streaming(ZipWriter<StreamWriter<W>>),
-    Seekable(ZipWriter<SeekWriter<W>>),
-}
-
-impl<W: Write + Seek> ZipWriterWrapper<W> {
-    pub fn new_seekable(inner: W) -> Self {
-        Self::Seekable(ZipWriter::new(SeekWriter::new(inner)))
-    }
-}
-
-impl<W: Write> ZipWriterWrapper<W> {
-    pub fn new_streaming(inner: W) -> Self {
-        Self::Streaming(ZipWriter::new_stream(inner))
+/// Validate that the entry's compression ratio is not excessively large, based
+/// on a constant factor for [`CompressionMethod::Deflate`]. This approach is
+/// identical to what rawzip recommends in their examples.
+fn validate_compression_ratio(
+    compressed_size: u64,
+    uncompressed_size: u64,
+    path: &[u8],
+) -> Result<(), rawzip::Error> {
+    if compressed_size > 0 && uncompressed_size / compressed_size > 1032 {
+        #[allow(clippy::cast_precision_loss)]
+        return Err(rawzip::ErrorKind::InvalidInput {
+            msg: format!(
+                "{:?} has excessively large compression ratio: {})",
+                path.as_bstr(),
+                uncompressed_size as f64 / compressed_size as f64,
+            ),
+        }
+        .into());
    }

-    pub fn start_file(
+    Ok(())
+}
+
+#[derive(Debug)]
+pub struct ZipEntriesSafe<'archive, 'buf, R> {
+    archive: &'archive ZipArchive<R>,
+    entries: ZipEntries<'archive, 'buf, R>,
+    compressed_ranges: Vec<(u64, u64)>,
+}
+
+impl<R: ReaderAt> ZipEntriesSafe<'_, '_, R> {
+    #[inline]
+    pub fn next_entry(
        &mut self,
-        name: impl ToString,
-        options: FileOptions<impl FileOptionExtension>,
-    ) -> ZipResult<u64> {
-        match self {
-            Self::Streaming(z) => z.start_file(name, options),
-            Self::Seekable(z) => z.start_file(name, options),
-        }
-    }
+    ) -> Result<Option<(ZipFileHeaderRecord<'_>, ZipEntry<'_, R>)>, rawzip::Error> {
+        let cd_entry = self.entries.next_entry()?;
+        let Some(cd_entry) = cd_entry else {
+            return Ok(None);
+        };

-    pub fn finish(self) -> ZipResult<W> {
-        match self {
-            Self::Streaming(z) => Ok(z.finish()?.into_inner()),
-            Self::Seekable(z) => Ok(z.finish()?.into_inner()),
+        validate_compression_ratio(
+            cd_entry.compressed_size_hint(),
+            cd_entry.uncompressed_size_hint(),
+            cd_entry.file_path().as_ref(),
+        )?;
+
+        let entry = self.archive.get_entry(cd_entry.wayfinder())?;
+
+        validate_and_add_range(
+            &mut self.compressed_ranges,
+            entry.compressed_data_range(),
+            cd_entry.file_path().as_ref(),
+        )?;
+
+        Ok(Some((cd_entry, entry)))
+    }
+}
+
+pub trait ZipEntriesSafeExt<R> {
+    fn entries_safe<'archive, 'buf>(
+        &'archive self,
+        buffer: &'buf mut [u8],
+    ) -> ZipEntriesSafe<'archive, 'buf, R>;
+}
+
+impl<R> ZipEntriesSafeExt<R> for ZipArchive<R> {
+    fn entries_safe<'archive, 'buf>(
+        &'archive self,
+        buffer: &'buf mut [u8],
+    ) -> ZipEntriesSafe<'archive, 'buf, R> {
+        let entries = self.entries(buffer);
+
+        ZipEntriesSafe {
+            archive: self,
+            entries,
+            compressed_ranges: Vec::new(),
        }
    }
 }

-impl<W: Write> Write for ZipWriterWrapper<W> {
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        match self {
-            Self::Streaming(z) => z.write(buf),
-            Self::Seekable(z) => z.write(buf),
-        }
+impl<R, T: ZipEntriesSafeExt<R>> ZipEntriesSafeExt<R> for &T {
+    fn entries_safe<'archive, 'buf>(
+        &'archive self,
+        buffer: &'buf mut [u8],
+    ) -> ZipEntriesSafe<'archive, 'buf, R> {
+        (**self).entries_safe(buffer)
    }
+}

-    fn flush(&mut self) -> io::Result<()> {
-        match self {
-            Self::Streaming(z) => z.flush(),
-            Self::Seekable(z) => z.flush(),
+impl<R, T: ZipEntriesSafeExt<R>> ZipEntriesSafeExt<R> for &mut T {
+    fn entries_safe<'archive, 'buf>(
+        &'archive self,
+        buffer: &'buf mut [u8],
+    ) -> ZipEntriesSafe<'archive, 'buf, R> {
+        (**self).entries_safe(buffer)
+    }
+}
+
+#[derive(Debug)]
+pub struct ZipSliceEntriesSafe<'data, T: AsRef<[u8]>> {
+    archive: &'data ZipSliceArchive<T>,
+    entries: ZipSliceEntries<'data>,
+    compressed_ranges: Vec<(u64, u64)>,
+}
+
+impl<'data, T: AsRef<[u8]>> ZipSliceEntriesSafe<'data, T> {
+    #[inline]
+    pub fn next_entry(
+        &mut self,
+    ) -> Result<Option<(ZipFileHeaderRecord<'data>, ZipSliceEntry<'data>)>, rawzip::Error> {
+        let cd_entry = self.entries.next_entry()?;
+        let Some(cd_entry) = cd_entry else {
+            return Ok(None);
+        };
+
+        validate_compression_ratio(
+            cd_entry.compressed_size_hint(),
+            cd_entry.uncompressed_size_hint(),
+            cd_entry.file_path().as_ref(),
+        )?;
+
+        let entry = self.archive.get_entry(cd_entry.wayfinder())?;
+
+        validate_and_add_range(
+            &mut self.compressed_ranges,
+            entry.compressed_data_range(),
+            cd_entry.file_path().as_ref(),
+        )?;
+
+        Ok(Some((cd_entry, entry)))
+    }
+}
+
+pub trait ZipSliceEntriesSafeExt<T: AsRef<[u8]>> {
+    fn entries_safe(&self) -> ZipSliceEntriesSafe<'_, T>;
+}
+
+impl<T: AsRef<[u8]>> ZipSliceEntriesSafeExt<T> for ZipSliceArchive<T> {
+    fn entries_safe(&self) -> ZipSliceEntriesSafe<'_, T> {
+        let entries = self.entries();
+
+        ZipSliceEntriesSafe {
+            archive: self,
+            entries,
+            compressed_ranges: Vec::new(),
        }
    }
 }
+
+impl<T: AsRef<[u8]>, U: ZipSliceEntriesSafeExt<T>> ZipSliceEntriesSafeExt<T> for &U {
+    fn entries_safe(&self) -> ZipSliceEntriesSafe<'_, T> {
+        (**self).entries_safe()
+    }
+}
+
+impl<T: AsRef<[u8]>, U: ZipSliceEntriesSafeExt<T>> ZipSliceEntriesSafeExt<T> for &mut U {
+    fn entries_safe(&self) -> ZipSliceEntriesSafe<'_, T> {
+        (**self).entries_safe()
+    }
+}
+
+fn compression_method_to_format(
+    compression_method: CompressionMethod,
+) -> Result<CompressedFormat, rawzip::Error> {
+    match compression_method {
+        CompressionMethod::Store => Ok(CompressedFormat::None),
+        CompressionMethod::Deflate => Ok(CompressedFormat::Deflate),
+        c => Err(rawzip::ErrorKind::InvalidInput {
+            msg: format!("Unsupported compression method: {c:?}"),
+        }
+        .into()),
+    }
+}
+
+pub fn compressed_reader<'archive, R: ReaderAt>(
+    entry: &ZipEntry<'archive, R>,
+    compression_method: CompressionMethod,
+) -> Result<CompressedReader<ZipReader<&'archive R>>, rawzip::Error> {
+    let format = compression_method_to_format(compression_method)?;
+
+    Ok(CompressedReader::with_format(entry.reader(), format))
+}
+
+pub fn compressed_slice_reader<'archive>(
+    entry: &ZipSliceEntry<'archive>,
+    compression_method: CompressionMethod,
+) -> Result<CompressedReader<Cursor<&'archive [u8]>>, rawzip::Error> {
+    let format = compression_method_to_format(compression_method)?;
+    let raw_reader = Cursor::new(entry.data());
+
+    Ok(CompressedReader::with_format(raw_reader, format))
+}
+
+pub fn verifying_reader<'archive, R: ReaderAt>(
+    entry: &ZipEntry<'archive, R>,
+    compression_method: CompressionMethod,
+) -> Result<ZipVerifier<CompressedReader<ZipReader<&'archive R>>, &'archive R>, rawzip::Error> {
+    compressed_reader(entry, compression_method).map(|r| entry.verifying_reader(r))
+}
+
+pub fn verifying_slice_reader<'archive>(
+    entry: &ZipSliceEntry<'archive>,
+    compression_method: CompressionMethod,
+) -> Result<ZipSliceVerifier<CompressedReader<Cursor<&'archive [u8]>>>, rawzip::Error> {
+    compressed_slice_reader(entry, compression_method).map(|r| entry.verifying_reader(r))
+}
+
+pub fn compressed_writer<W: Write>(
+    writer: W,
+    compression_method: CompressionMethod,
+) -> Result<CompressedWriter<W>, rawzip::Error> {
+    use compression::Error;
+
+    let format = compression_method_to_format(compression_method)?;
+
+    match CompressedWriter::new(writer, format) {
+        Ok(w) => Ok(w),
+        Err(Error::Lz4Init(e) | Error::XzInit(e)) => Err(e.into()),
+        Err(Error::UnknownFormat | Error::AutoDetect(_)) => unreachable!(),
+    }
+}
+
+pub trait ZipArchiveReadAtExt {
+    fn from_read_at<R: ReadAt>(
+        file: R,
+        buffer: &mut [u8],
+    ) -> Result<ZipArchive<ReaderAtWrapper<R>>, rawzip::Error> {
+        let end_offset = file.file_len()?;
+
+        ZipLocator::new()
+            .locate_in_reader(ReaderAtWrapper(file), buffer, end_offset)
+            .map_err(|(_, e)| e)
+    }
+}
+
+impl ZipArchiveReadAtExt for ZipArchive<()> {}
+
+pub struct ReaderAtWrapper<R: ReadAt>(R);
+
+impl<R: ReadAt> ReaderAt for ReaderAtWrapper<R> {
+    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
+        ReadAt::read_at(&self.0, buf, offset)
+    }
+}
+
+#[derive(Clone, Copy, FromBytes, IntoBytes, KnownLayout, Immutable, Unaligned)]
+#[repr(C, packed)]
+struct ZipLocalHeader {
+    signature: little_endian::U32,
+    version_needed: little_endian::U16,
+    flags: little_endian::U16,
+    compression_method: little_endian::U16,
+    last_mod_time: little_endian::U16,
+    last_mod_date: little_endian::U16,
+    crc32: little_endian::U32,
+    compressed_size: little_endian::U32,
+    uncompressed_size: little_endian::U32,
+    file_name_len: little_endian::U16,
+    extra_field_len: little_endian::U16,
+}
+
+#[derive(Clone, Copy, FromBytes, IntoBytes, KnownLayout, Immutable, Unaligned)]
+#[repr(C, packed)]
+struct ZipCentralHeader {
+    pub signature: little_endian::U32,
+    pub version_made_by: little_endian::U16,
+    pub version_needed: little_endian::U16,
+    pub flags: little_endian::U16,
+    pub compression_method: little_endian::U16,
+    pub last_mod_time: little_endian::U16,
+    pub last_mod_date: little_endian::U16,
+    pub crc32: little_endian::U32,
+    pub compressed_size: little_endian::U32,
+    pub uncompressed_size: little_endian::U32,
+    pub file_name_len: little_endian::U16,
+    pub extra_field_len: little_endian::U16,
+    pub file_comment_len: little_endian::U16,
+    pub disk_number_start: little_endian::U16,
+    pub internal_file_attrs: little_endian::U16,
+    pub external_file_attrs: little_endian::U32,
+    pub local_header_offset: little_endian::U32,
+}
+
+/// Convert a streaming zip into a non-streaming one. If any entry uses ZIP64,
+/// the local header must contain an [`ExtraFieldId::ANDROID_ZIP_ALIGNMENT`]
+/// extra field with sufficient size (16 bytes to be safe). This is used as
+/// reserved space for creating a new [`ExtraFieldId::ZIP64`] extra field. Any
+/// leftover space must be at least 4 bytes so that a new extra field can
+/// consume the space. The existing data descriptor will remain in the gap
+/// between entries and data will not be shifted.
+pub fn make_non_streaming(file: impl Read + Write + Seek) -> Result<(), rawzip::Error> {
+    // rawzip currently does not expose the CRC32 value, so we'll have to read
+    // it ourselves.
+    struct EntryInfo {
+        local_header_offset: u64,
+        central_header_offset: u64,
+        crc32: u32,
+        compressed_size: u64,
+        uncompressed_size: u64,
+        local_extra_fields: Vec<u8>,
+    }
+
+    let mut to_update = vec![];
+
+    let mut central_buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+    let mut local_buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+    let archive = ZipArchive::from_seekable(file, &mut central_buffer)?;
+    let mut entries = archive.entries_safe(&mut central_buffer);
+
+    while let Some((cd_entry, entry)) = entries.next_entry()? {
+        let wf = cd_entry.wayfinder();
+
+        let local_header = entry.local_header(&mut local_buffer)?;
+
+        to_update.push(EntryInfo {
+            local_header_offset: cd_entry.local_header_offset(),
+            central_header_offset: cd_entry.central_directory_offset(),
+            crc32: cd_entry.crc32(),
+            compressed_size: wf.compressed_size_hint(),
+            uncompressed_size: wf.uncompressed_size_hint(),
+            local_extra_fields: local_header.extra_fields().remaining_bytes().to_vec(),
+        });
+    }
+
+    let mut file = archive.into_inner().into_inner();
+
+    for entry in to_update {
+        // Clear the central header's streaming flag.
+        let mut central_flags = little_endian::U16::new(0);
+        file.seek(SeekFrom::Start(entry.central_header_offset + 8))?;
+        file.read_exact(central_flags.as_mut_bytes())?;
+        central_flags &= !0x8;
+        file.seek_relative(-(central_flags.as_bytes().len() as i64))?;
+        file.write_all(central_flags.as_bytes())?;
+
+        file.seek(SeekFrom::Start(entry.local_header_offset))?;
+
+        let mut local_header = ZipLocalHeader::new_zeroed();
+        file.read_exact(local_header.as_mut_bytes())?;
+
+        // Clear the local header's streaming flag.
+        local_header.flags &= !0x8;
+
+        // Remove dependency on the data descriptor.
+        local_header.crc32.set(entry.crc32);
+
+        let compressed_is_zip64 = entry.compressed_size >= 0xffffffff;
+        let uncompressed_is_zip64 = entry.uncompressed_size >= 0xffffffff;
+
+        if compressed_is_zip64 {
+            local_header.compressed_size.set(0xffffffff);
+        } else {
+            local_header
+                .compressed_size
+                .set(entry.compressed_size as u32);
+        }
+
+        if uncompressed_is_zip64 {
+            local_header.uncompressed_size.set(0xffffffff);
+        } else {
+            local_header
+                .uncompressed_size
+                .set(entry.uncompressed_size as u32);
+        }
+
+        file.seek_relative(-(local_header.as_bytes().len() as i64))?;
+        file.write_all(local_header.as_bytes())?;
+
+        file.seek_relative(i64::from(local_header.file_name_len.get()))?;
+
+        if !compressed_is_zip64 && !uncompressed_is_zip64 {
+            continue;
+        }
+
+        let mut extra_fields = Vec::with_capacity(entry.local_extra_fields.len());
+        let mut patched_placeholder = false;
+
+        for (id, data) in ExtraFields::new(&entry.local_extra_fields) {
+            if id == ExtraFieldId::ANDROID_ZIP_ALIGNMENT {
+                let zip64_len =
+                    8 * (usize::from(compressed_is_zip64) + usize::from(uncompressed_is_zip64));
+
+                // Any unused space needs to be at least 4 bytes, so we can
+                // properly write a new extra field for padding.
+                let have_needed_space = match data.len().cmp(&zip64_len) {
+                    Ordering::Less => false,
+                    Ordering::Equal => true,
+                    Ordering::Greater => data.len() - zip64_len >= 4,
+                };
+                if !have_needed_space {
+                    return Err(rawzip::ErrorKind::InvalidInput {
+                        msg: format!(
+                            "Invalid reserved ZIP64 local extra field size: {}",
+                            data.len()
+                        ),
+                    }
+                    .into());
+                }
+
+                // The order is indeed backwards compared to the header
+                // fields (APPNOTE 4.5.3).
+                extra_fields.extend_from_slice(&ExtraFieldId::ZIP64.as_u16().to_le_bytes());
+                extra_fields.extend_from_slice(&(zip64_len as u16).to_le_bytes());
+                if uncompressed_is_zip64 {
+                    extra_fields.extend_from_slice(&entry.uncompressed_size.to_le_bytes());
+                }
+                if compressed_is_zip64 {
+                    extra_fields.extend_from_slice(&entry.compressed_size.to_le_bytes());
+                }
+
+                // Keep using ANDROID_ZIP_ALIGNMENT for padding.
+                if data.len() > zip64_len {
+                    let padding_len = data.len() - zip64_len - 4;
+                    extra_fields.extend_from_slice(&id.as_u16().to_le_bytes());
+                    extra_fields.extend_from_slice(&(padding_len as u16).to_le_bytes());
+                    extra_fields.resize(extra_fields.len() + padding_len, 0);
+                }
+
+                patched_placeholder = true;
+            } else if id == ExtraFieldId::ZIP64 {
+                return Err(rawzip::ErrorKind::InvalidInput {
+                    msg: "Unexpected ZIP64 extra field present".to_owned(),
+                }
+                .into());
+            } else {
+                extra_fields.extend_from_slice(&id.as_u16().to_le_bytes());
+                extra_fields.extend_from_slice(&(data.len() as u16).to_le_bytes());
+                extra_fields.extend_from_slice(data);
+            }
+        }
+
+        assert_eq!(extra_fields.len(), entry.local_extra_fields.len());
+
+        if !patched_placeholder {
+            return Err(rawzip::ErrorKind::InvalidInput {
+                msg: "ZIP64 required, but no placeholder extra field found".to_owned(),
+            }
+            .into());
+        }
+
+        file.write_all(&extra_fields)?;
+    }
+
+    Ok(())
+}
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{
+    borrow::Cow,
    cmp::Ordering,
    collections::{HashMap, HashSet},
    fmt::Write,
@@ -16,6 +17,7 @@ use std::{

 use bstr::ByteSlice;
 use lzma_rust2::{CheckType, XZOptions, XZWriter};
+use rawzip::{RECOMMENDED_BUFFER_SIZE, ZipArchive};
 use rayon::iter::{IntoParallelRefIterator, IntoParallelRefMutIterator, ParallelIterator};
 use regex::bytes::Regex;
 use ring::digest::Context;
@@ -23,7 +25,6 @@ use rsa::RsaPublicKey;
 use thiserror::Error;
 use tracing::{Span, debug, debug_span, trace, warn};
 use x509_cert::Certificate;
-use zip::{ZipArchive, result::ZipError};

 use crate::{
    crypto::{self, RsaSigningKey},
@@ -32,6 +33,7 @@ use crate::{
        bootimage::{self, BootImage, BootImageExt, RamdiskMeta},
        compression::{self, CompressedFormat, CompressedReader, CompressedWriter},
        cpio::{self, CpioEntry, CpioEntryData},
+        zip::{self, ZipEntriesSafeExt, ZipFileHeaderRecordExt, ZipSliceEntriesSafeExt},
    },
    patch::otacert::{self, OtaCertBuildFlags},
    stream::{self, FromReader, HashingWriter, ReadSeek, SectionReader, ToWriter, WriteSeek},
@@ -85,13 +87,15 @@ pub enum Error {
    #[error("Failed to XZ compress entry: {:?}", .0.as_bstr())]
    XzCompress(Vec<u8>, #[source] io::Error),
    #[error("Failed to open zip file: {0:?}")]
-    ZipOpen(PathBuf, #[source] ZipError),
+    ZipOpen(PathBuf, #[source] rawzip::Error),
+    #[error("Failed to list zip entries")]
+    ZipEntryList(#[source] rawzip::Error),
+    #[error("Missing zip entry: {0:?}")]
+    ZipEntryMissing(Cow<'static, str>),
    #[error("Failed to open zip entry: {0:?}")]
-    ZipEntryOpen(&'static str, #[source] ZipError),
+    ZipEntryOpen(Cow<'static, str>, #[source] rawzip::Error),
    #[error("Failed to read zip entry: {0:?}")]
-    ZipEntryRead(&'static str, #[source] io::Error),
-    #[error("Failed to open zip entry #{0}")]
-    ZipIndexOpen(usize, #[source] ZipError),
+    ZipEntryRead(Cow<'static, str>, #[source] io::Error),
    #[error("Failed to open file: {0:?}")]
    FileOpen(PathBuf, #[source] io::Error),
 }
@@ -254,35 +258,46 @@ impl MagiskRootPatcher {
        })
    }

-    fn get_version(path: &Path) -> Result<u32> {
-        let reader = File::open(path)
-            .map(BufReader::new)
-            .map_err(|e| Error::FileOpen(path.to_owned(), e))?;
-        let mut zip = ZipArchive::new(reader).map_err(|e| Error::ZipOpen(path.to_owned(), e))?;
-        let entry = zip
-            .by_name(Self::ZIP_UTIL_FUNCTIONS)
-            .map_err(|e| Error::ZipEntryOpen(Self::ZIP_UTIL_FUNCTIONS, e))?;
-        let mut entry = BufReader::new(entry);
-        let mut line = String::new();
+    fn get_version(apk_path: &Path) -> Result<u32> {
+        let file = File::open(apk_path).map_err(|e| Error::FileOpen(apk_path.to_owned(), e))?;
+        let mut buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+        let archive = ZipArchive::from_file(file, &mut buffer)
+            .map_err(|e| Error::ZipOpen(apk_path.to_owned(), e))?;
+        let mut entries = archive.entries_safe(&mut buffer);

-        loop {
-            line.clear();
-            let n = entry
-                .read_line(&mut line)
-                .map_err(|e| Error::ZipEntryRead(Self::ZIP_UTIL_FUNCTIONS, e))?;
-            if n == 0 {
-                return Err(Error::FindMagiskVersion(path.to_owned()));
+        while let Some((cd_entry, entry)) = entries.next_entry().map_err(Error::ZipEntryList)? {
+            let path = cd_entry.file_path_utf8().map_err(Error::ZipEntryList)?;
+
+            if path != Self::ZIP_UTIL_FUNCTIONS {
+                continue;
            }

-            if let Some(suffix) = line.trim_end().strip_prefix("MAGISK_VER_CODE=") {
-                trace!("Magisk version code line: {line:?}");
+            let mut reader = zip::verifying_reader(&entry, cd_entry.compression_method())
+                .map(BufReader::new)
+                .map_err(|e| Error::ZipEntryOpen(Self::ZIP_UTIL_FUNCTIONS.into(), e))?;
+            let mut line = String::new();

-                let version = suffix
-                    .parse()
-                    .map_err(|e| Error::ParseMagiskVersion(suffix.to_owned(), e))?;
-                return Ok(version);
+            loop {
+                line.clear();
+                let n = reader
+                    .read_line(&mut line)
+                    .map_err(|e| Error::ZipEntryRead(Self::ZIP_UTIL_FUNCTIONS.into(), e))?;
+                if n == 0 {
+                    return Err(Error::FindMagiskVersion(apk_path.to_owned()));
+                }
+
+                if let Some(suffix) = line.trim_end().strip_prefix("MAGISK_VER_CODE=") {
+                    trace!("Magisk version code line: {line:?}");
+
+                    let version = suffix
+                        .parse()
+                        .map_err(|e| Error::ParseMagiskVersion(suffix.to_owned(), e))?;
+                    return Ok(version);
+                }
            }
        }
+
+        Err(Error::ZipEntryMissing(Self::ZIP_UTIL_FUNCTIONS.into()))
    }

    fn xz_compress(name: &[u8], reader: impl Read, cancel_signal: &AtomicBool) -> Result<Vec<u8>> {
@@ -436,12 +451,6 @@ impl BootImagePatch for MagiskRootPatcher {
    }

    fn patch(&self, boot_image: &mut BootImage, cancel_signal: &AtomicBool) -> Result<()> {
-        let zip_reader = File::open(&self.apk_path)
-            .map(BufReader::new)
-            .map_err(|e| Error::FileOpen(self.apk_path.clone(), e))?;
-        let mut zip =
-            ZipArchive::new(zip_reader).map_err(|e| Error::ZipOpen(self.apk_path.clone(), e))?;
-
        // Load the first ramdisk. If it doesn't exist, we have to generate one
        // from scratch.
        let ramdisk = match boot_image {
@@ -467,60 +476,95 @@ impl BootImagePatch for MagiskRootPatcher {
        // Delete the original init.
        entries.retain(|e| e.path != b"init");

-        // Add magiskinit.
-        {
-            let mut zip_entry = zip
-                .by_name(Self::ZIP_MAGISKINIT)
-                .map_err(|e| Error::ZipEntryOpen(Self::ZIP_MAGISKINIT, e))?;
-            let mut data = vec![];
-            zip_entry
-                .read_to_end(&mut data)
-                .map_err(|e| Error::ZipEntryRead(Self::ZIP_MAGISKINIT, e))?;
+        let file =
+            File::open(&self.apk_path).map_err(|e| Error::FileOpen(self.apk_path.clone(), e))?;
+        let mut buffer = vec![0u8; RECOMMENDED_BUFFER_SIZE];
+        let archive = ZipArchive::from_file(file, &mut buffer)
+            .map_err(|e| Error::ZipOpen(self.apk_path.clone(), e))?;
+
+        let mut zip_entries = archive.entries_safe(&mut buffer);
+        let mut found_magiskinit = false;
+        let mut found_libmagisk = false;
+
+        while let Some((cd_entry, entry)) = zip_entries.next_entry().map_err(Error::ZipEntryList)? {
+            let path = cd_entry.file_path_utf8().map_err(Error::ZipEntryList)?;
+
+            // magiskinit is the only entry that is not xz-compressed.
+            if path == Self::ZIP_MAGISKINIT {
+                let mut reader = zip::verifying_reader(&entry, cd_entry.compression_method())
+                    .map_err(|e| Error::ZipEntryOpen(Self::ZIP_MAGISKINIT.into(), e))?;
+                let mut data = vec![];
+
+                reader
+                    .read_to_end(&mut data)
+                    .map_err(|e| Error::ZipEntryRead(Self::ZIP_MAGISKINIT.into(), e))?;
+
+                entries.push(CpioEntry::new_file(
+                    b"init",
+                    0o750,
+                    CpioEntryData::Data(data),
+                ));
+
+                found_magiskinit = true;
+                continue;
+            }
+
+            // Keep a 'static version of the zip path.
+            let (path, cpio_path): (_, &[u8]) = match path {
+                // Newer Magisk versions only include a single binary for the
+                // target ABI in the ramdisk. This was introduced in commit
+                // fb5ee86615ed3df830e8538f8b39b1b133caea34.
+                p if p == Self::ZIP_LIBMAGISK => {
+                    debug!("Single libmagisk");
+                    found_libmagisk = true;
+                    (Self::ZIP_LIBMAGISK, b"overlay.d/sbin/magisk.xz")
+                }
+                // Older Magisk versions include the 64-bit binary and,
+                // optionally, the 32-bit binary if the device supports it. We
+                // unconditionally include the magisk32 because the boot image
+                // itself doesn't have sufficient information to determine if a
+                // device is 64-bit only.
+                p if p == Self::ZIP_LIBMAGISK32 => {
+                    debug!("Split libmagisk32");
+                    found_libmagisk = true;
+                    (Self::ZIP_LIBMAGISK32, b"overlay.d/sbin/magisk32.xz")
+                }
+                p if p == Self::ZIP_LIBMAGISK64 => {
+                    debug!("Split libmagisk64");
+                    found_libmagisk = true;
+                    (Self::ZIP_LIBMAGISK64, b"overlay.d/sbin/magisk64.xz")
+                }
+                // The stub apk was introduced in commit
+                // ad0e6511e11ebec65aa9b5b916e1397342850319.
+                p if p == Self::ZIP_STUB => {
+                    debug!("Magisk stub found");
+                    (Self::ZIP_STUB, b"overlay.d/sbin/stub.xz")
+                }
+                // init-ld was introduced in commit
+                // 33aebb59763b6ec27209563035303700e998633d.
+                p if p == Self::ZIP_INIT_LD => {
+                    debug!("Magisk init-ld found");
+                    (Self::ZIP_INIT_LD, b"overlay.d/sbin/init-ld.xz")
+                }
+                _ => continue,
+            };
+
+            let reader = zip::verifying_reader(&entry, cd_entry.compression_method())
+                .map_err(|e| Error::ZipEntryOpen(path.into(), e))?;
+
+            let buf = Self::xz_compress(path.as_bytes(), reader, cancel_signal)?;

            entries.push(CpioEntry::new_file(
-                b"init",
-                0o750,
-                CpioEntryData::Data(data),
+                cpio_path,
+                0o644,
+                CpioEntryData::Data(buf),
            ));
        }

-        let mut xz_files = HashMap::<&str, &[u8]>::new();
-        if zip.file_names().any(|n| n == Self::ZIP_LIBMAGISK) {
-            // Newer Magisk versions only include a single binary for the target
-            // ABI in the ramdisk. fb5ee86615ed3df830e8538f8b39b1b133caea34.
-            debug!("Single libmagisk");
-            xz_files.insert(Self::ZIP_LIBMAGISK, b"overlay.d/sbin/magisk.xz");
-        } else {
-            // Older Magisk versions include the 64-bit binary and, optionally,
-            // the 32-bit binary if the device supports it. We unconditionally
-            // include the magisk32 because the boot image itself doesn't have
-            // sufficient information to determine if a device is 64-bit only.
-            debug!("Split libmagisk32/libmagisk64");
-            xz_files.insert(Self::ZIP_LIBMAGISK32, b"overlay.d/sbin/magisk32.xz");
-            xz_files.insert(Self::ZIP_LIBMAGISK64, b"overlay.d/sbin/magisk64.xz");
-        }
-
-        // Add stub apk, which only exists after Magisk commit
-        // ad0e6511e11ebec65aa9b5b916e1397342850319.
-        if zip.file_names().any(|n| n == Self::ZIP_STUB) {
-            debug!("Magisk stub found");
-            xz_files.insert(Self::ZIP_STUB, b"overlay.d/sbin/stub.xz");
-        }
-
-        // Add init-ld, which only exists after Magisk commit
-        // 33aebb59763b6ec27209563035303700e998633d
-        if zip.file_names().any(|n| n == Self::ZIP_INIT_LD) {
-            debug!("Magisk init-ld found");
-            xz_files.insert(Self::ZIP_INIT_LD, b"overlay.d/sbin/init-ld.xz");
-        }
-
-        for (source, target) in xz_files {
-            let reader = zip
-                .by_name(source)
-                .map_err(|e| Error::ZipEntryOpen(source, e))?;
-            let buf = Self::xz_compress(source.as_bytes(), reader, cancel_signal)?;
-
-            entries.push(CpioEntry::new_file(target, 0o644, CpioEntryData::Data(buf)));
+        if !found_magiskinit {
+            return Err(Error::ZipEntryMissing(Self::ZIP_MAGISKINIT.into()));
+        } else if !found_libmagisk {
+            return Err(Error::ZipEntryMissing(Self::ZIP_LIBMAGISK.into()));
        }

        // Create Magisk .backup directory structure.
@@ -602,7 +646,7 @@ pub struct OtaCertPatcher {
 }

 impl OtaCertPatcher {
-    const OTACERTS_PATH: &'static [u8] = b"system/etc/security/otacerts.zip";
+    const OTACERTS_PATH: &'static str = "system/etc/security/otacerts.zip";

    pub fn new(cert: Certificate) -> Self {
        Self { cert }
@@ -628,29 +672,33 @@ impl OtaCertPatcher {
            }

            let (entries, _) = load_ramdisk(ramdisk, cancel_signal)?;
-            let Some(entry) = entries.iter().find(|e| e.path == Self::OTACERTS_PATH) else {
+            let Some(entry) = entries
+                .iter()
+                .find(|e| e.path == Self::OTACERTS_PATH.as_bytes())
+            else {
                continue;
            };
            let CpioEntryData::Data(data) = &entry.data else {
                continue;
            };

-            let mut zip = ZipArchive::new(Cursor::new(&data)).map_err(|e| {
-                Error::ZipOpen(str::from_utf8(Self::OTACERTS_PATH).unwrap().into(), e)
-            })?;
+            let archive = ZipArchive::from_slice(data)
+                .map_err(|e| Error::ZipOpen(Self::OTACERTS_PATH.into(), e))?;
+            let mut entries = archive.entries_safe();

-            for index in 0..zip.len() {
-                let zip_entry = zip
-                    .by_index(index)
-                    .map_err(|e| Error::ZipIndexOpen(index, e))?;
-                if !zip_entry.name().ends_with(".x509.pem") {
-                    debug!("Skipping invalid entry path: {}", zip_entry.name());
+            while let Some((cd_entry, entry)) = entries.next_entry().map_err(Error::ZipEntryList)? {
+                let path = cd_entry.file_path_utf8().map_err(Error::ZipEntryList)?;
+
+                if !path.ends_with(".x509.pem") {
+                    debug!("Skipping invalid entry path: {path:?}");
                    continue;
                }

-                let path = PathBuf::from(zip_entry.name());
+                let reader = zip::verifying_slice_reader(&entry, cd_entry.compression_method())
+                    .map_err(|e| Error::ZipEntryOpen(path.to_owned().into(), e))?;
+
                let certificate =
-                    crypto::read_pem_cert(&path, zip_entry).map_err(Error::OtaCertLoad)?;
+                    crypto::read_pem_cert(Path::new(path), reader).map_err(Error::OtaCertLoad)?;
                certificates.push(certificate);
            }
        }
@@ -664,7 +712,10 @@ impl OtaCertPatcher {
        cancel_signal: &AtomicBool,
    ) -> Result<bool> {
        let (mut entries, ramdisk_format) = load_ramdisk(ramdisk, cancel_signal)?;
-        let Some(entry) = entries.iter_mut().find(|e| e.path == Self::OTACERTS_PATH) else {
+        let Some(entry) = entries
+            .iter_mut()
+            .find(|e| e.path == Self::OTACERTS_PATH.as_bytes())
+        else {
            return Ok(false);
        };

@@ -705,7 +756,10 @@ impl BootImagePatch for OtaCertPatcher {

                let (entries, _) = load_ramdisk(ramdisk, cancel_signal)
                    .map_err(|e| TargetsError::Load(name.to_owned(), e))?;
-                if entries.iter().any(|e| e.path == Self::OTACERTS_PATH) {
+                if entries
+                    .iter()
+                    .any(|e| e.path == Self::OTACERTS_PATH.as_bytes())
+                {
                    targets.push(name);
                    continue 'outer;
                }
@@ -740,7 +794,7 @@ impl BootImagePatch for OtaCertPatcher {
        // out of future updates if the OTA certificate mechanism has changed.
        Err(Error::Validation(format!(
            "No ramdisk contains {:?}",
-            Self::OTACERTS_PATH.as_bstr(),
+            Self::OTACERTS_PATH,
        )))
    }
 }
@@ -1210,9 +1264,20 @@ fn save_boot_image(
    Ok(())
 }

+pub trait BootImageOpener {
+    fn open_original(&self, name: &str) -> io::Result<Box<dyn ReadSeek + Sync>>;
+
+    fn open_replacement(&self, name: &str) -> io::Result<Box<dyn WriteSeek + Sync>> {
+        Err(io::Error::new(
+            io::ErrorKind::NotFound,
+            format!("{name} boot image not found"),
+        ))
+    }
+}
+
 pub fn load_boot_images<'a>(
    names: &[&'a str],
-    open_input: impl Fn(&str) -> io::Result<Box<dyn ReadSeek>> + Sync,
+    opener: &(dyn BootImageOpener + Sync),
 ) -> TargetsResult<HashMap<&'a str, BootImageInfo>> {
    let parent_span = Span::current();

@@ -1220,8 +1285,9 @@ pub fn load_boot_images<'a>(
        .par_iter()
        .map(|&name| {
            let _span = debug_span!(parent: &parent_span, "image", name).entered();
-            let mut reader =
-                open_input(name).map_err(|e| TargetsError::Open(name.to_owned(), e))?;
+            let mut reader = opener
+                .open_original(name)
+                .map_err(|e| TargetsError::Open(name.to_owned(), e))?;

            let info =
                load_boot_image(&mut reader).map_err(|e| TargetsError::Load(name.to_owned(), e))?;
@@ -1238,8 +1304,7 @@ pub fn load_boot_images<'a>(
 /// be opened from multiple threads, but at most once each.
 pub fn patch_boot_images<'a>(
    names: &[&'a str],
-    open_input: impl Fn(&str) -> io::Result<Box<dyn ReadSeek>> + Sync,
-    open_output: impl Fn(&str) -> io::Result<Box<dyn WriteSeek>> + Sync,
+    opener: &(dyn BootImageOpener + Sync),
    key: &RsaSigningKey,
    patchers: &[Box<dyn BootImagePatch + Sync>],
    cancel_signal: &AtomicBool,
@@ -1252,7 +1317,7 @@ pub fn patch_boot_images<'a>(
    }

    // Preparse all images. Some patchers need to inspect every candidate.
-    let mut images = load_boot_images(names, open_input)?;
+    let mut images = load_boot_images(names, opener)?;

    // Find the targets that each patcher wants to patch.
    let all_targets = patchers
@@ -1303,7 +1368,9 @@ pub fn patch_boot_images<'a>(
    // Resign and write new images.
    groups.par_iter_mut().try_for_each(|(&name, (info, _))| {
        let _span = debug_span!(parent: &parent_span, "image", name).entered();
-        let mut writer = open_output(name).map_err(|e| TargetsError::Open(name.to_owned(), e))?;
+        let mut writer = opener
+            .open_replacement(name)
+            .map_err(|e| TargetsError::Open(name.to_owned(), e))?;

        save_boot_image(&mut writer, info, key).map_err(|e| TargetsError::Save(name.to_owned(), e))
    })?;
@@ -1,15 +1,18 @@
-// SPDX-FileCopyrightText: 2023-2024 Andrew Gunnerson
+// SPDX-FileCopyrightText: 2023-2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{borrow::Cow, cmp::Ordering, io::Cursor, path::Path};

 use bitflags::bitflags;
+use rawzip::{CompressionMethod, ZipArchiveWriter};
 use thiserror::Error;
 use tracing::trace;
 use x509_cert::{Certificate, der::asn1::BitString};
-use zip::{CompressionMethod, DateTime, ZipWriter, result::ZipError, write::SimpleFileOptions};

-use crate::{crypto, format::ota};
+use crate::{
+    crypto,
+    format::{ota, zip},
+};

 #[derive(Debug, Error)]
 pub enum Error {
@@ -18,7 +21,7 @@ pub enum Error {
    #[error("New otacerts.zip is too large to fit in {0} bytes")]
    ZipTooLarge(usize),
    #[error("Failed to write otacerts zip")]
-    ZipWrite(#[source] ZipError),
+    ZipWrite(#[source] rawzip::Error),
    #[error("Failed to write certificate to otacerts zip")]
    CertWrite(#[source] crypto::Error),
 }
@@ -71,19 +74,23 @@ bitflags! {
 /// Create an `otacerts.zip` file containing the specified certificate.
 pub fn create_zip(cert: &Certificate, flags: OtaCertBuildFlags) -> Result<Vec<u8>> {
    let raw_writer = Cursor::new(Vec::new());
-    let mut writer = ZipWriter::new(raw_writer);
+    let mut writer = ZipArchiveWriter::new(raw_writer);

    let compression_method = if flags.contains(OtaCertBuildFlags::COMPRESS_DEFLATE) {
-        CompressionMethod::Deflated
+        CompressionMethod::Deflate
    } else {
-        CompressionMethod::Stored
+        CompressionMethod::Store
    };

-    let options = SimpleFileOptions::default()
-        .last_modified_time(DateTime::default())
-        .compression_method(compression_method);
    let name = "ota.x509.pem";
-    writer.start_file(name, options).map_err(Error::ZipWrite)?;
+    let (entry_writer, data_config) = writer
+        .new_file(name)
+        .compression_method(compression_method)
+        .start()
+        .map_err(Error::ZipWrite)?;
+    let compressed_writer =
+        zip::compressed_writer(entry_writer, compression_method).map_err(Error::ZipWrite)?;
+    let mut data_writer = data_config.wrap(compressed_writer);

    let cert = if flags.is_empty() {
        Cow::Borrowed(cert)
@@ -112,9 +119,16 @@ pub fn create_zip(cert: &Certificate, flags: OtaCertBuildFlags) -> Result<Vec<u8
        Cow::Owned(modified)
    };

-    crypto::write_pem_cert(Path::new(name), &mut writer, &cert).map_err(Error::CertWrite)?;
+    crypto::write_pem_cert(Path::new(name), &mut data_writer, &cert).map_err(Error::CertWrite)?;

-    let raw_writer = writer.finish().map_err(Error::ZipWrite)?;
+    data_writer
+        .finish()
+        .and_then(|(w, d)| w.finish()?.finish(d))
+        .map_err(Error::ZipWrite)?;
+
+    let mut raw_writer = writer.finish().map_err(Error::ZipWrite)?;
+
+    zip::make_non_streaming(&mut raw_writer).map_err(Error::ZipWrite)?;

    Ok(raw_writer.into_inner())
 }
@@ -1,27 +1,28 @@
-// SPDX-FileCopyrightText: 2023-2024 Andrew Gunnerson
+// SPDX-FileCopyrightText: 2023-2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{
-    io::{self, Cursor, SeekFrom},
+    io::{self, Seek, SeekFrom, Write},
    ops::Range,
    sync::atomic::AtomicBool,
 };

 use memchr::memmem;
+use rawzip::ZipArchive;
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use thiserror::Error;
 use tracing::{Span, debug, debug_span, trace};
 use x509_cert::Certificate;
-use zip::ZipArchive;

 use crate::{
    crypto::RsaSigningKey,
    format::{
        avb::{self, AppendedDescriptorMut, Footer},
        ota,
+        zip::{ZipFileHeaderRecordExt, ZipSliceEntriesSafeExt},
    },
    patch::otacert,
-    stream::{self, ReadFixedSizeExt, ReadSeekReopen, SectionReader, WriteSeekReopen},
+    stream::{self, ReadFixedSizeExt, ReadWriteAt, UserPosFile},
    util,
 };

@@ -68,25 +69,28 @@ fn find_zip_bounds(data: &[u8], eocd_offset: usize) -> Option<Range<usize>> {

    trace!("Found zip bounds: {:?}", start..end);

-    let reader = SectionReader::new(Cursor::new(data), start as u64, (end - start) as u64).ok()?;
-    let mut zip_reader = ZipArchive::new(reader).ok()?;
+    let archive = ZipArchive::from_slice(&data[start..end]).ok()?;
+    let mut entries = archive.entries_safe();
+    let mut matches = 0;

-    if zip_reader.is_empty() {
+    while let Some((cd_entry, _)) = entries.next_entry().ok()? {
+        let path = cd_entry.file_path_utf8().ok()?;
+
+        if !path.ends_with(".x509.pem") {
+            // otacerts.zip files only contain files named this way.
+            trace!("Excluded due to invalid name: {path:?}");
+            return None;
+        }
+
+        matches += 1;
+    }
+
+    if matches == 0 {
        // otacerts.zip files contain at least one cert.
        trace!("Zip is empty");
        return None;
    }

-    for index in 0..zip_reader.len() {
-        let entry = zip_reader.by_index_raw(index).ok()?;
-
-        if !entry.name().ends_with(".x509.pem") {
-            // otacerts.zip files only contain files named this way.
-            trace!("Excluded due to invalid name: {:?}", entry.name());
-            return None;
-        }
-    }
-
    debug!("Found otacerts.zip candidate");

    // There's one or more entries and every one is named *.x509.pem.
@@ -96,8 +100,7 @@ fn find_zip_bounds(data: &[u8], eocd_offset: usize) -> Option<Range<usize>> {
 /// Replace `otacerts.zip` with a new one containing the new certificate, but
 /// padded to the same size. If the new zip is too large, the certificate will
 /// be modified to remove unnecessary components until it fits. All operations
-/// run in parallel where possible. The input and output must refer to the same
-/// file and will be reopened from multiple threads.
+/// run in parallel where possible.
 ///
 /// Returns two sorted and non-overlapping lists of byte ranges that were
 /// modified. The first list are the byte regions within the filesystem data
@@ -108,8 +111,7 @@ fn find_zip_bounds(data: &[u8], eocd_offset: usize) -> Option<Range<usize>> {
 /// modified.
 #[allow(clippy::type_complexity)]
 pub fn patch_system_image(
-    input: &(dyn ReadSeekReopen + Sync),
-    output: &(dyn WriteSeekReopen + Sync),
+    raw_file: &(dyn ReadWriteAt + Sync),
    certificate: &Certificate,
    key: &RsaSigningKey,
    cancel_signal: &AtomicBool,
@@ -122,8 +124,7 @@ pub fn patch_system_image(
    let parent_span = Span::current();

    let (mut header, footer, image_size) =
-        avb::load_image(input.reopen_boxed().map_err(Error::ReadData)?)
-            .map_err(Error::AvbUpdate)?;
+        avb::load_image(UserPosFile::new(raw_file)).map_err(Error::AvbUpdate)?;
    let Some(mut footer) = footer else {
        return Err(Error::NoFooter);
    };
@@ -144,15 +145,13 @@ pub fn patch_system_image(
            let offset = chunk * CHUNK_SIZE;
            let size = CHUNK_SIZE.min(footer.original_image_size - offset);

-            let mut reader = input.reopen_boxed().map_err(Error::ReadData)?;
-            reader
-                .seek(SeekFrom::Start(offset))
+            let mut file = UserPosFile::new(raw_file);
+            file.seek(SeekFrom::Start(offset))
                .map_err(Error::ReadData)?;
-            let buf = reader
+            let buf = file
                .read_vec_exact(size as usize)
                .map_err(Error::ReadData)?;

-            let mut writer = output.reopen_boxed().map_err(Error::WriteData)?;
            let mut ranges = Vec::<Range<u64>>::new();

            for eocd_offset_rel in memmem::find_iter(&buf, ota::ZIP_EOCD_MAGIC) {
@@ -171,10 +170,9 @@ pub fn patch_system_image(

                stream::check_cancel(cancel_signal).map_err(Error::WriteData)?;

-                writer
-                    .seek(SeekFrom::Start(bounds.start))
+                file.seek(SeekFrom::Start(bounds.start))
                    .map_err(Error::WriteData)?;
-                writer.write_all(&new_zip).map_err(Error::WriteData)?;
+                file.write_all(&new_zip).map_err(Error::WriteData)?;

                ranges.push(bounds);
            }
@@ -195,7 +193,7 @@ pub fn patch_system_image(
    let update_ranges = Some(modified_ranges.as_slice());

    descriptor
-        .update(input, output, update_ranges, cancel_signal)
+        .update(raw_file, update_ranges, cancel_signal)
        .map_err(Error::AvbUpdate)?;

    if !header.public_key.is_empty() {
@@ -204,8 +202,8 @@ pub fn patch_system_image(
        header.sign(key).map_err(Error::AvbUpdate)?;
    }

-    let writer = output.reopen_boxed().map_err(Error::WriteData)?;
-    avb::write_appended_image(writer, &header, &mut footer, Some(image_size))
+    let file = UserPosFile::new(raw_file);
+    avb::write_appended_image(file, &header, &mut footer, Some(image_size))
        .map_err(Error::AvbUpdate)?;

    let AppendedDescriptorMut::HashTree(descriptor) =
@@ -3,9 +3,9 @@

 use std::{
    fs::File,
-    io::{self, BufReader, BufWriter, Cursor, Read, Seek, SeekFrom, Write},
+    io::{self, Read, Seek, SeekFrom, Write},
    sync::{
-        Arc, Mutex, RwLock,
+        Arc, Mutex,
        atomic::{AtomicBool, Ordering},
    },
 };
@@ -15,39 +15,32 @@ use ring::digest::Context;

 use crate::util;

-/// A trait for seekable readers. This is only needed because `dyn Read + Seek`
-/// is not a valid construct in Rust yet.
-pub trait ReadSeek: Read + Seek {}
+/// This is only needed because `dyn Read + Seek` is not a valid construct in
+/// Rust yet.
+pub trait ReadSeek: Read + Seek {
+    // https://github.com/rust-lang/rust/issues/145752
+    fn issue_145752(&self) {}
+}

 impl<R: Read + Seek> ReadSeek for R {}

-/// A trait for seekable writers. This is only needed because `dyn Write + Seek`
-/// is not a valid construct in Rust yet.
-pub trait WriteSeek: Write + Seek {}
+/// This is only needed because `dyn Write + Seek` is not a valid construct in
+/// Rust yet.
+pub trait WriteSeek: Write + Seek {
+    // https://github.com/rust-lang/rust/issues/145752
+    fn issue_145752(&self) {}
+}

 impl<W: Write + Seek> WriteSeek for W {}

-/// A trait for seekable and reopenable readers.
-pub trait ReadSeekReopen: ReadSeek {
-    fn reopen_boxed(&self) -> io::Result<Box<dyn ReadSeek>>;
+/// This is only needed because `dyn Read + Write + Seek` is not a valid
+/// construct in Rust yet.
+pub trait ReadWriteSeek: ReadSeek + WriteSeek {
+    // https://github.com/rust-lang/rust/issues/145752
+    fn issue_145752(&self) {}
 }

-impl<R: ReadSeek + Reopen + 'static> ReadSeekReopen for R {
-    fn reopen_boxed(&self) -> io::Result<Box<dyn ReadSeek>> {
-        Ok(Box::new(self.reopen()?))
-    }
-}
-
-/// A trait for seekable and reopenable writers.
-pub trait WriteSeekReopen: WriteSeek {
-    fn reopen_boxed(&self) -> io::Result<Box<dyn WriteSeek>>;
-}
-
-impl<W: WriteSeek + Reopen + 'static> WriteSeekReopen for W {
-    fn reopen_boxed(&self) -> io::Result<Box<dyn WriteSeek>> {
-        Ok(Box::new(self.reopen()?))
-    }
-}
+impl<W: ReadSeek + WriteSeek> ReadWriteSeek for W {}

 /// Common function for reading a structure from a reader.
 pub trait FromReader<R: Read>: Sized {
@@ -144,25 +137,121 @@ impl<R: Read> ReadFixedSizeExt for R {
    }
 }

-/// Extensions for file-like types to reopen themselves.
-pub trait Reopen: Sized {
-    /// Open a new handle to the same file. The new handle is independently
-    /// seekable and the file offset is initially set to 0.
-    fn reopen(&self) -> io::Result<Self>;
+/// Extensions for file-like types to query the file size. No guarantees are
+/// made about the state of the underlying file position after performing any
+/// operation.
+pub trait FileLen {
+    fn file_len(&self) -> io::Result<u64>;
 }

-impl<R: Read + Reopen> Reopen for BufReader<R> {
-    fn reopen(&self) -> io::Result<Self> {
-        Ok(Self::new(self.get_ref().reopen()?))
+macro_rules! file_len_blanket_impl {
+    ($type:ty) => {
+        impl<F: ?Sized + FileLen> FileLen for $type {
+            fn file_len(&self) -> io::Result<u64> {
+                (**self).file_len()
+            }
+        }
+    };
+}
+
+file_len_blanket_impl!(&F);
+file_len_blanket_impl!(Arc<F>);
+file_len_blanket_impl!(Box<F>);
+
+/// Extensions for file-like types that support multi-threaded reads at specific
+/// offsets. No guarantees are made about the state of underlying file position
+/// after performing any operation.
+pub trait ReadAt: FileLen {
+    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize>;
+
+    fn read_exact_at(&self, buf: &mut [u8], offset: u64) -> io::Result<()> {
+        let n = self.read_at(buf, offset)?;
+        if n != buf.len() {
+            return Err(io::Error::new(
+                io::ErrorKind::UnexpectedEof,
+                format!(
+                    "Expected to read {} bytes at {offset}, but reached EOF after {n} bytes",
+                    buf.len(),
+                ),
+            ));
+        }
+        Ok(())
    }
 }

-impl<W: Write + Reopen> Reopen for BufWriter<W> {
-    fn reopen(&self) -> io::Result<Self> {
-        Ok(Self::new(self.get_ref().reopen()?))
-    }
+macro_rules! read_at_blanket_impl {
+    ($type:ty) => {
+        impl<R: ?Sized + ReadAt> ReadAt for $type {
+            fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
+                (**self).read_at(buf, offset)
+            }
+
+            fn read_exact_at(&self, buf: &mut [u8], offset: u64) -> io::Result<()> {
+                (**self).read_exact_at(buf, offset)
+            }
+        }
+    };
 }

+read_at_blanket_impl!(&R);
+read_at_blanket_impl!(Arc<R>);
+read_at_blanket_impl!(Box<R>);
+
+/// Extensions for file-like types that support multi-threaded writes at
+/// specific offsets. The behavior is unspecified if writes would overlap. No
+/// guarantees are made about the state of the underlying file position after
+/// performing any operation.
+pub trait WriteAt: FileLen {
+    fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize>;
+
+    fn write_all_at(&self, buf: &[u8], offset: u64) -> io::Result<()> {
+        let n = self.write_at(buf, offset)?;
+        if n != buf.len() {
+            return Err(io::Error::new(
+                io::ErrorKind::UnexpectedEof,
+                format!(
+                    "Expected to write {} bytes at {offset}, but reached EOF after {n} bytes",
+                    buf.len(),
+                ),
+            ));
+        }
+        Ok(())
+    }
+
+    fn file_flush(&self) -> io::Result<()>;
+}
+
+macro_rules! write_at_blanket_impl {
+    ($type:ty) => {
+        impl<W: ?Sized + WriteAt> WriteAt for $type {
+            fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
+                (**self).write_at(buf, offset)
+            }
+
+            fn write_all_at(&self, buf: &[u8], offset: u64) -> io::Result<()> {
+                (**self).write_all_at(buf, offset)
+            }
+
+            fn file_flush(&self) -> io::Result<()> {
+                (**self).file_flush()
+            }
+        }
+    };
+}
+
+write_at_blanket_impl!(&W);
+write_at_blanket_impl!(Arc<W>);
+write_at_blanket_impl!(Box<W>);
+
+/// This is only needed because `dyn ReadAt + WriteAt` is not a valid construct
+/// in Rust yet.
+pub trait ReadWriteAt: ReadAt + WriteAt {
+    // https://github.com/rust-lang/rust/issues/145752
+    fn issue_145752(&self) {}
+}
+
+impl<F: ReadAt + WriteAt> ReadWriteAt for F {}
+
 /// A reader wrapper that implements [`Seek`], but only for reporting the
 /// current file position.
 pub struct CountingReader<R> {
@@ -320,14 +409,6 @@ impl<R: Read + Seek> SectionReader<R> {
    }
 }

-impl<R: Read + Seek + Reopen> Reopen for SectionReader<R> {
-    fn reopen(&self) -> io::Result<Self> {
-        let inner = self.inner.reopen()?;
-
-        Self::new(inner, self.start, self.size)
-    }
-}
-
 impl<R: Read + Seek> Read for SectionReader<R> {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        let to_read = self.size.saturating_sub(self.pos).min(buf.len() as u64) as usize;
@@ -370,93 +451,179 @@ impl<R: Read + Seek> Seek for SectionReader<R> {
    }
 }

-/// A file wrapper that uses a userspace file offset. A reopened instance uses
-/// the same underlying kernel file descriptor, but a new userspace file offset,
-/// initially set to 0.
-#[derive(Debug)]
-pub struct PSeekFile {
-    // The lock is needed because flush() takes a `&mut self`.
-    file: Arc<RwLock<File>>,
-    offset: u64,
+/// A reader wrapper that only allows reading a specific section of a file.
+pub struct SectionReaderAt<R> {
+    inner: R,
+    start: u64,
+    size: u64,
 }

-impl PSeekFile {
-    pub fn new(file: File) -> Self {
-        Self {
-            file: Arc::new(RwLock::new(file)),
-            offset: 0,
-        }
+impl<R: ReadAt> SectionReaderAt<R> {
+    pub fn new(inner: R, start: u64, size: u64) -> io::Result<Self> {
+        Ok(Self { inner, start, size })
    }

-    pub fn set_len(&self, size: u64) -> io::Result<()> {
-        let file_locked = self.file.read().unwrap();
-        file_locked.set_len(size)
+    pub fn into_inner(self) -> R {
+        self.inner
    }
+}

+impl<R> FileLen for SectionReaderAt<R> {
+    fn file_len(&self) -> io::Result<u64> {
+        Ok(self.size)
+    }
+}
+
+impl<R: ReadAt> ReadAt for SectionReaderAt<R> {
+    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
+        let to_read = self.size.saturating_sub(offset).min(buf.len() as u64) as usize;
+
+        self.inner.read_at(&mut buf[..to_read], self.start + offset)
+    }
+}
+
+/// Regular files support parallel reads.
+impl ReadAt for File {
    /// Read data from offset. The kernel's file position *will* be changed.
    #[cfg(windows)]
-    fn read_at(&self, buf: &mut [u8]) -> io::Result<usize> {
+    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
        use std::os::windows::fs::FileExt;
-        self.file.read().unwrap().seek_read(buf, self.offset)
+        FileExt::seek_read(self, buf, offset)
    }

    /// Read data from offset. The kernel's file position will *not* be changed.
    #[cfg(unix)]
-    fn read_at(&self, buf: &mut [u8]) -> io::Result<usize> {
+    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
        use std::os::unix::fs::FileExt;
-        self.file.read().unwrap().read_at(buf, self.offset)
+        FileExt::read_at(self, buf, offset)
    }
+}

+/// Regular files support parallel writes.
+impl WriteAt for File {
    /// Write data to offset. The kernel's file position *will* be changed.
    #[cfg(windows)]
-    fn write_at(&self, buf: &[u8]) -> io::Result<usize> {
+    fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
        use std::os::windows::fs::FileExt;
-        self.file.read().unwrap().seek_write(buf, self.offset)
+        FileExt::seek_write(self, buf, offset)
    }

    /// Write data to offset. The kernel's file position will *not* be changed.
    #[cfg(unix)]
-    fn write_at(&self, buf: &[u8]) -> io::Result<usize> {
+    fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
        use std::os::unix::fs::FileExt;
-        self.file.read().unwrap().write_at(buf, self.offset)
+        FileExt::write_at(self, buf, offset)
+    }
+
+    fn file_flush(&self) -> io::Result<()> {
+        (&*self).flush()
    }
 }

-impl Reopen for PSeekFile {
-    fn reopen(&self) -> io::Result<Self> {
-        Ok(Self {
-            file: self.file.clone(),
-            offset: 0,
-        })
+impl FileLen for File {
+    fn file_len(&self) -> io::Result<u64> {
+        (&*self).seek(SeekFrom::End(0))
    }
 }

-impl Read for PSeekFile {
+/// A file wrapper that implements [`ReadAt`] and [`WriteAt`] on top of
+/// [`Read`], [`Write`], and [`Seek`] via a mutex that makes operations
+/// single-threaded. This is the inverse of [`UserPosFile`].
+pub struct MutexFile<F>(Mutex<F>);
+
+impl<F> MutexFile<F> {
+    pub fn new(file: F) -> Self {
+        Self(Mutex::new(file))
+    }
+
+    pub fn into_inner(self) -> F {
+        self.0.into_inner().unwrap()
+    }
+}
+
+impl<F: Seek> FileLen for MutexFile<F> {
+    fn file_len(&self) -> io::Result<u64> {
+        let mut inner = self.0.lock().unwrap();
+        inner.seek(SeekFrom::End(0))
+    }
+}
+
+impl<F: Read + Seek> ReadAt for MutexFile<F> {
+    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
+        let mut inner = self.0.lock().unwrap();
+        let pos = inner.stream_position()?;
+
+        inner.seek(SeekFrom::Start(offset))?;
+
+        let result = inner.read(buf);
+
+        inner.seek(SeekFrom::Start(pos))?;
+
+        result
+    }
+}
+
+impl<F: Write + Seek> WriteAt for MutexFile<F> {
+    fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
+        let mut inner = self.0.lock().unwrap();
+        let pos = inner.stream_position()?;
+
+        inner.seek(SeekFrom::Start(offset))?;
+
+        let result = inner.write(buf);
+
+        inner.seek(SeekFrom::Start(pos))?;
+
+        result
+    }
+
+    fn file_flush(&self) -> io::Result<()> {
+        let mut inner = self.0.lock().unwrap();
+        inner.flush()
+    }
+}
+
+/// A file wrapper than implements the standard [`Read`], [`Write`], and
+/// [`Seek`] traits on top of [`ReadAt`] and [`WriteAt`]. The file position is
+/// unique for every instance, even if the underlying file is shared. This is
+/// the inverse of [`MutexFile`].
+pub struct UserPosFile<F> {
+    file: F,
+    offset: u64,
+}
+
+impl<F> UserPosFile<F> {
+    pub fn new(file: F) -> Self {
+        Self { file, offset: 0 }
+    }
+}
+
+impl<F: ReadAt> Read for UserPosFile<F> {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        let n = self.read_at(buf)?;
+        let n = self.file.read_at(buf, self.offset)?;
        self.offset += n as u64;
        Ok(n)
    }
 }

-impl Write for PSeekFile {
+impl<F: WriteAt> Write for UserPosFile<F> {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        let n = self.write_at(buf)?;
+        let n = self.file.write_at(buf, self.offset)?;
        self.offset += n as u64;
        Ok(n)
    }

    fn flush(&mut self) -> io::Result<()> {
-        self.file.write().unwrap().flush()
+        self.file.file_flush()
    }
 }

-impl Seek for PSeekFile {
+impl<F: FileLen> Seek for UserPosFile<F> {
    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
        self.offset = match pos {
            SeekFrom::Start(o) => o,
            SeekFrom::End(o) => {
-                let file_size = self.file.read().unwrap().metadata()?.len();
+                let file_size = self.file.file_len()?;
                file_size
                    .to_i64()
                    .and_then(|s| s.checked_add(o))
@@ -485,70 +652,6 @@ impl Seek for PSeekFile {
    }
 }

-/// A small wrapper around a [`Cursor`] that allows multiple instances to share
-/// the same underlying file. All reads, writes, and seeks are single-threaded.
-/// This is useful for scenarios where data needs to be copied from multiple
-/// readers into different parts of the same [`SharedCursor`] writer and the
-/// read operation is significantly more expensive than the write operation (eg.
-/// due to decompression).
-#[derive(Default)]
-pub struct SharedCursor {
-    inner: Arc<Mutex<Cursor<Vec<u8>>>>,
-    offset: u64,
-}
-
-impl SharedCursor {
-    pub fn new() -> Self {
-        Self::default()
-    }
-}
-
-impl Reopen for SharedCursor {
-    fn reopen(&self) -> io::Result<Self> {
-        Ok(Self {
-            inner: self.inner.clone(),
-            offset: 0,
-        })
-    }
-}
-
-impl Read for SharedCursor {
-    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        let mut inner = self.inner.lock().unwrap();
-        inner.seek(SeekFrom::Start(self.offset))?;
-
-        let n = inner.read(buf)?;
-        self.offset += n as u64;
-
-        Ok(n)
-    }
-}
-
-impl Write for SharedCursor {
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        let mut inner = self.inner.lock().unwrap();
-        inner.seek(SeekFrom::Start(self.offset))?;
-
-        let n = inner.write(buf)?;
-        self.offset += n as u64;
-
-        Ok(n)
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        let mut inner = self.inner.lock().unwrap();
-        inner.flush()
-    }
-}
-
-impl Seek for SharedCursor {
-    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
-        let mut inner = self.inner.lock().unwrap();
-        self.offset = inner.seek(pos)?;
-        Ok(self.offset)
-    }
-}
-
 /// Returns an I/O error with the [`io::ErrorKind::Interrupted`] type if
 /// `cancel_signal` is true. This should be called frequently in I/O loops for
 /// cancellation to be responsive.
@@ -648,10 +751,9 @@ mod tests {

    use ring::digest::Context;

-    use super::{
-        CountingReader, CountingWriter, HashingReader, HashingWriter, PSeekFile, ReadDiscardExt,
-        Reopen, SectionReader, SharedCursor, WriteZerosExt,
-    };
+    use crate::stream::FileLen;
+
+    use super::*;

    const FOOBAR_SHA256: [u8; 32] = [
        0xc3, 0xab, 0x8f, 0xf1, 0x37, 0x20, 0xe8, 0xad, 0x90, 0x47, 0xdd, 0x39, 0x46, 0x6b, 0x3c,
@@ -776,7 +878,7 @@ mod tests {
        assert_eq!(&buf[..4], b"nner");

        buf = *b"\0\0\0\0\0";
-        reader.seek(SeekFrom::Current(-5)).unwrap();
+        reader.seek_relative(-5).unwrap();
        reader.read_exact(&mut buf[..3]).unwrap();
        assert_eq!(&buf[..3], b"inn");

@@ -785,91 +887,98 @@ mod tests {
    }

    #[test]
-    fn pseek_file() {
-        let raw_file = tempfile::tempfile().unwrap();
-        let mut a = PSeekFile::new(raw_file);
-        let mut b = a.reopen().unwrap();
-        let mut c = b.reopen().unwrap();
+    fn section_reader_at() {
+        let raw_reader = MutexFile::new(Cursor::new(b"fooinnerbar"));
+        let reader = SectionReaderAt::new(raw_reader, 3, 5).unwrap();

-        b.write_all(b"foobar").unwrap();
-        c.write_all(b"hello").unwrap();
-        b.write_all(b"world").unwrap();
-        c.seek(SeekFrom::Start(0)).unwrap();
-        c.write_all(b"hi").unwrap();
+        let mut buf = [0u8; 5];
+        reader.read_exact_at(&mut buf[3..5], 3).unwrap();
+        reader.read_exact_at(&mut buf[..3], 0).unwrap();
+        assert_eq!(&buf, b"inner");

-        let mut buf = [0u8; 11];
-        a.read_exact(&mut buf).unwrap();
-        assert_eq!(&buf, b"hillorworld");
-
-        let n = a.read_discard(1).unwrap();
+        let n = reader.read_at(&mut buf, 5).unwrap();
        assert_eq!(n, 0);
    }

    #[test]
-    fn shared_cursor() {
-        let mut a = SharedCursor::default();
-        let mut b = a.reopen().unwrap();
-        let mut c = b.reopen().unwrap();
+    fn mutex_file() {
+        let file = MutexFile::new(Cursor::new(Vec::new()));
+        assert_eq!(file.file_len().unwrap(), 0);

-        b.write_all(b"foobar").unwrap();
-        c.write_all(b"hello").unwrap();
-        b.write_all(b"world").unwrap();
-        c.seek(SeekFrom::Start(0)).unwrap();
-        c.write_all(b"hi").unwrap();
+        file.write_all_at(b"bar", 3).unwrap();
+        assert_eq!(file.file_len().unwrap(), 6);

-        let mut buf = [0u8; 11];
-        a.read_exact(&mut buf).unwrap();
-        assert_eq!(&buf, b"hillorworld");
+        file.write_all_at(b"foo", 0).unwrap();
+        assert_eq!(file.file_len().unwrap(), 6);

-        let n = a.read_discard(1).unwrap();
-        assert_eq!(n, 0);
+        let data = file.into_inner().into_inner();
+        assert_eq!(data, b"foobar");
    }

    #[test]
-    fn copy() {
+    fn user_pos_file() {
+        let mut raw_file = tempfile::tempfile().unwrap();
+        raw_file.write_all(b"foobar").unwrap();
+
+        let mut file = UserPosFile::new(raw_file);
+        let mut buf = [0u8; 3];
+
+        file.rewind().unwrap();
+        file.read_exact(&mut buf).unwrap();
+        assert_eq!(&buf, b"foo");
+
+        let pos = file.seek(SeekFrom::End(-3)).unwrap();
+        assert_eq!(pos, 3);
+
+        file.read_exact(&mut buf).unwrap();
+        assert_eq!(&buf, b"bar");
+    }
+
+    #[test]
+    fn copy_functions() {
        let cancel_signal = AtomicBool::new(false);
        let mut reader = Cursor::new(b"foobar");
        let mut writer = Cursor::new([0u8; 6]);

-        super::copy_n(&mut reader, &mut writer, 6, &cancel_signal).unwrap();
+        copy_n(&mut reader, &mut writer, 6, &cancel_signal).unwrap();
        assert_eq!(writer.get_ref(), b"foobar");

        // Reader early EOF.
        reader.seek(SeekFrom::Start(3)).unwrap();
        writer.rewind().unwrap();
-        let err = super::copy_n(&mut reader, &mut writer, 6, &cancel_signal).unwrap_err();
+        let err = copy_n(&mut reader, &mut writer, 6, &cancel_signal).unwrap_err();
        assert_eq!(err.kind(), io::ErrorKind::UnexpectedEof);

        // Writer early EOF.
        reader.rewind().unwrap();
        writer.seek(SeekFrom::Start(3)).unwrap();
-        let err = super::copy_n(&mut reader, &mut writer, 6, &cancel_signal).unwrap_err();
+        let err = copy_n(&mut reader, &mut writer, 6, &cancel_signal).unwrap_err();
        assert_eq!(err.kind(), io::ErrorKind::WriteZero);

        reader.rewind().unwrap();
        writer.rewind().unwrap();
-        let n = super::copy(&mut reader, &mut writer, &cancel_signal).unwrap();
+        let n = copy(&mut reader, &mut writer, &cancel_signal).unwrap();
        assert_eq!(n, 6);
        assert_eq!(writer.get_ref(), b"foobar");

        // Reader early EOF.
        reader.seek(SeekFrom::Start(3)).unwrap();
        writer.rewind().unwrap();
-        let n = super::copy(&mut reader, &mut writer, &cancel_signal).unwrap();
+        let n = copy(&mut reader, &mut writer, &cancel_signal).unwrap();
        assert_eq!(n, 3);

        // Writer early EOF.
        reader.rewind().unwrap();
        writer.seek(SeekFrom::Start(3)).unwrap();
-        let err = super::copy(&mut reader, &mut writer, &cancel_signal).unwrap_err();
+        let err = copy(&mut reader, &mut writer, &cancel_signal).unwrap_err();
        assert_eq!(err.kind(), io::ErrorKind::WriteZero);

        reader.rewind().unwrap();
        writer.rewind().unwrap();
        cancel_signal.store(true, Ordering::SeqCst);
-        let err = super::copy_n(&mut reader, &mut writer, 6, &cancel_signal).unwrap_err();
+        let err = copy_n(&mut reader, &mut writer, 6, &cancel_signal).unwrap_err();
        assert_eq!(err.kind(), io::ErrorKind::Interrupted);
-        let err = super::copy(&mut reader, &mut writer, &cancel_signal).unwrap_err();
+        let err = copy(&mut reader, &mut writer, &cancel_signal).unwrap_err();
        assert_eq!(err.kind(), io::ErrorKind::Interrupted);
    }
 }
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Andrew Gunnerson
+// SPDX-FileCopyrightText: 2023-2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

 use std::{
@@ -18,7 +18,7 @@ use avbroot::{
        ChainPartitionDescriptor, Descriptor, Footer, HashDescriptor, HashTreeDescriptor, Header,
        KernelCmdlineDescriptor, PropertyDescriptor,
    },
-    stream::SharedCursor,
+    stream::{MutexFile, UserPosFile},
 };

 fn get_test_key() -> RsaSigningKey {
@@ -306,16 +306,17 @@ fn round_trip_appended_hash_tree_image_fixed_size() {
        reserved: repeat_array(&[0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]),
    };

-    let mut writer = SharedCursor::default();
+    let writer = MutexFile::new(Cursor::new(Vec::new()));
+    let mut pos_writer = UserPosFile::new(&writer);
    let cancel_signal = AtomicBool::new(false);

    // Write the raw partition data.
-    writer.write_all(&raw_data).unwrap();
+    pos_writer.write_all(&raw_data).unwrap();

    // Generate and write the hash tree and FEC data.
    match header.appended_descriptor_mut().unwrap() {
        AppendedDescriptorMut::HashTree(d) => {
-            d.update(&writer, &writer, None, &cancel_signal).unwrap();
+            d.update(&writer, None, &cancel_signal).unwrap();
        }
        AppendedDescriptorMut::Hash(_) => panic!("Expected hash tree descriptor"),
    }
@@ -334,10 +335,10 @@ fn round_trip_appended_hash_tree_image_fixed_size() {
    assert_eq!(header.verify().unwrap().unwrap(), key.to_public_key());

    // Write vbmeta structures.
-    avb::write_appended_image(&mut writer, &header, &mut footer, Some(image_size)).unwrap();
+    avb::write_appended_image(&mut pos_writer, &header, &mut footer, Some(image_size)).unwrap();
    let mut data = Vec::new();
-    writer.rewind().unwrap();
-    writer.read_to_end(&mut data).unwrap();
+    pos_writer.rewind().unwrap();
+    pos_writer.read_to_end(&mut data).unwrap();

    // Verify checksum of the output.
    assert_eq!(
@@ -413,16 +414,17 @@ fn round_trip_appended_hash_tree_image_minimum_size() {
        reserved: repeat_array(&[0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]),
    };

-    let mut writer = SharedCursor::default();
+    let writer = MutexFile::new(Cursor::new(Vec::new()));
+    let mut pos_writer = UserPosFile::new(&writer);
    let cancel_signal = AtomicBool::new(false);

    // Write the raw partition data.
-    writer.write_all(&raw_data).unwrap();
+    pos_writer.write_all(&raw_data).unwrap();

    // Generate and write the hash tree and FEC data.
    match header.appended_descriptor_mut().unwrap() {
        AppendedDescriptorMut::HashTree(d) => {
-            d.update(&writer, &writer, None, &cancel_signal).unwrap();
+            d.update(&writer, None, &cancel_signal).unwrap();
        }
        AppendedDescriptorMut::Hash(_) => panic!("Expected hash tree descriptor"),
    }
@@ -441,10 +443,10 @@ fn round_trip_appended_hash_tree_image_minimum_size() {
    assert_eq!(header.verify().unwrap().unwrap(), key.to_public_key());

    // Write vbmeta structures.
-    avb::write_appended_image(&mut writer, &header, &mut footer, None).unwrap();
+    avb::write_appended_image(&mut pos_writer, &header, &mut footer, None).unwrap();
    let mut data = Vec::new();
-    writer.rewind().unwrap();
-    writer.read_to_end(&mut data).unwrap();
+    pos_writer.rewind().unwrap();
+    pos_writer.read_to_end(&mut data).unwrap();

    // Verify checksum of the output.
    assert_eq!(
@@ -72,5 +72,4 @@ unknown-registry = "deny"
 unknown-git = "deny"
 allow-git = [
    "https://github.com/chenxiaolong/system-properties",
-    "https://github.com/chenxiaolong/zip2",
 ]
@@ -14,6 +14,7 @@ avbroot = { path = "../avbroot" }
 clap = { version = "4.4.1", features = ["derive"] }
 ctrlc = "3.4.0"
 hex = { version = "0.4.3", features = ["serde"] }
+rawzip = "0.4.0"
 ring = "0.17.14"
 rsa = { version = "0.9.6", features = ["hazmat"] }
 serde = { version = "1.0.188", features = ["derive"] }
@@ -24,13 +25,5 @@ tracing = "0.1.40"
 tracing-subscriber = "0.3.18"
 x509-cert = "0.2.5"

-# https://github.com/zip-rs/zip2/pull/367
-# https://github.com/zip-rs/zip2/pull/368
-# For getting the data offset when writing new zip entries.
-[dependencies.zip]
-git = "https://github.com/chenxiaolong/zip2"
-rev = "59685f4dadbfee8cb3ea74c8fbb402b60d8137e8"
-default-features = false
-
 [lints]
 workspace = true
@@ -14,8 +14,9 @@ security_patch_level = "2024-01-01"

 [profile.pixel_v4_gki.vabc]
 # CoW v3 is used starting with the Google Pixel 9a.
-version = "V3"
+version = { V3 = { compression_factor = 65536 } }
 algo = { kind = "Lz4" }
+force_compression_factor = false

 [profile.pixel_v4_gki.partitions.boot]
 avb.signed = true
@@ -51,12 +52,12 @@ data.version = "vendor_v4"
 data.ramdisks = [["otacerts", "first_stage", "dsu_key_dir"]]

 [profile.pixel_v4_gki.hashes_streaming]
-original = "4e283ad1e3450795a32f46445bf626f6af983f52bd0a3484b49f8740c1029653"
-patched = "837861bf64e9387380e02d740b21c94e60c41bba4161d85ab44fc5ce86f19631"
+original = "ea96196191e3a4133db4aff45d47aa3468514e29e0a724faac8081cbf4adf808"
+patched = "357a448d1a7505b2308ce1c2d19b063e606c60e7349784913a48cdc3f6d50aa4"

 [profile.pixel_v4_gki.hashes_seekable]
-original = "0ab2403a2634f00063c44f9a477a672205922ede189442e18850dd8efceb5d6f"
-patched = "2d94841c3be6cc1739f4c7ad5d9db048301b3f93f8ccd510e2c825bf13ecff90"
+original = "f6615ae355eba38689d24aa535981d09175d4832e7c65c04cdd89aa95d21f09d"
+patched = "9195ba963d9897af2f0821ff6051c1efe3fe130055b7936bedf2cd189998fd89"

 # Google Pixel 6a
 # What's unique: boot (boot v4, no ramdisk) + vendor_boot (vendor v4, 2 ramdisks)
@@ -64,6 +65,8 @@ patched = "2d94841c3be6cc1739f4c7ad5d9db048301b3f93f8ccd510e2c825bf13ecff90"
 [profile.pixel_v4_non_gki.vabc]
 version = "V2"
 algo = { kind = "Lz4" }
+# delta_generator sets it for v2, even though it's not used.
+force_compression_factor = true

 [profile.pixel_v4_non_gki.partitions.boot]
 avb.signed = true
@@ -93,12 +96,12 @@ data.version = "vendor_v4"
 data.ramdisks = [["init", "otacerts", "first_stage", "dsu_key_dir"], ["dlkm"]]

 [profile.pixel_v4_non_gki.hashes_streaming]
-original = "c3a978b7225632875d3b1e87e852494b1a69019f5ba4099cf3981503623facca"
-patched = "cf0ef7429c4657875018d10d7302aaca371b21c5968af234aabd941304f0035b"
+original = "cb2a2e406d2b4c68c8a38f819256a10ada0ed5a4732822bec35bdf7bcdc458eb"
+patched = "12f15d29fceeb18af14c9a805de3aedb7f270fe8ec316d9d0fe37fb0c667eacd"

 [profile.pixel_v4_non_gki.hashes_seekable]
-original = "cc11ee5a5be66bf34dcb6834a9a635016fa9f82dd0d9a2fb1029aa4f218d1d2e"
-patched = "e2fb7d3ce2c697372fb342ae5cd7bb606cd764f06a2aa8a2d6d7bd2c88456780"
+original = "9450c212c34fe55453b52345c7cc22f72397dc80d9ddc792eafc20b461c2afc9"
+patched = "5018c579df9608f9dfe3add2afd8b176de61ba267376cf3a3e422ecc9d3dd112"

 # Google Pixel 4a 5G
 # What's unique: boot (boot v3) + vendor_boot (vendor v3)
@@ -106,6 +109,7 @@ patched = "e2fb7d3ce2c697372fb342ae5cd7bb606cd764f06a2aa8a2d6d7bd2c88456780"
 [profile.pixel_v3.vabc]
 version = "V2"
 algo = { kind = "Gz" }
+force_compression_factor = false

 [profile.pixel_v3.partitions.boot]
 avb.signed = true
@@ -136,12 +140,12 @@ data.version = "vendor_v3"
 data.ramdisks = [["otacerts", "first_stage", "dsu_key_dir"]]

 [profile.pixel_v3.hashes_streaming]
-original = "d12d92c051bcc832cc9ceef1d46c415af80a09808a984db4c42a88d65d644a8b"
-patched = "408496eb2cca51c0563eceaa3a9def95a5c42acff938850a8577aaa047331284"
+original = "4b864b906a13ec98b1d6c3440a5eca7404ec63d073080e80a3b84afabcbd2fa2"
+patched = "a9077fe32dee8eb7a0369c1334d8f3378ae8044814ae04da700f33294b12a4d8"

 [profile.pixel_v3.hashes_seekable]
-original = "63505cfd7c2c9d948a5ee150cf53f448f11c83cdce3919fd43231640bf002812"
-patched = "b246497de1588d41b919ba002b37dff13cb565682aa3e086e543b25ead7d7aaf"
+original = "e0e93ee11de56992f3a5f543858c1d11858b4deb76a91a4caf4fb0f3f34be855"
+patched = "8730b398367179a0be092a67e4714f09c2267c656fe3e42ec1f8b43bb3a28634"

 # Google Pixel 4a
 # What's unique: boot (boot v2)
@@ -169,9 +173,9 @@ data.type = "vbmeta"
 data.deps = ["system"]

 [profile.pixel_v2.hashes_streaming]
-original = "c303728f4ee9c42ef990bb576bd0688635b263a67127d2a986caf574c9eedd63"
-patched = "e907db408767f81223e3ae53dd8a44c6f59f4702a016093cd6983499c9391ff0"
+original = "abc0ad7f80020018101437c2494d6564a877df663d208a123267fc100734c175"
+patched = "b1876455f5be9d5b6eafc598a017ad10e5e76339137f8b29777097ab19cdc3b0"

 [profile.pixel_v2.hashes_seekable]
-original = "951b1f70bef7736b9e06f3215357fcebf8a4925872cd31691198fdda9d7c04ce"
-patched = "2b1bfe46f41942be88e09b40000745c68ed133900d7970f57d15019683a1ba87"
+original = "57d4ac5ab7d362a593f3c02f3d2044b5400c10db0f732741a2d18e025d4231ec"
+patched = "40d7674be14e19747e7ead118e0f4faf50880c638dfb4bfc0d0154b0e9202d3f"
@@ -110,6 +110,7 @@ pub struct Partition {
 pub struct VabcSettings {
    pub version: CowVersion,
    pub algo: VabcAlgo,
+    pub force_compression_factor: bool,
 }

 #[derive(Clone, Serialize, Deserialize)]
@@ -37,7 +37,7 @@ use avbroot::{
        ota::{self, SigningWriter, ZipEntry, ZipMode},
        padding,
        payload::{self, CowVersion, PayloadHeader, PayloadWriter, VabcParams},
-        zip::ZipWriterWrapper,
+        zip,
    },
    patch::otacert::{self, OtaCertBuildFlags},
    protobuf::{
@@ -46,16 +46,16 @@ use avbroot::{
            DeltaArchiveManifest, DynamicPartitionGroup, DynamicPartitionMetadata, PartitionUpdate,
        },
    },
-    stream::{self, CountingWriter, FromReader, HashingReader, PSeekFile, Reopen, ToWriter},
+    stream::{self, FromReader, HashingReader, ToWriter},
    util,
 };
 use clap::Parser;
+use rawzip::{CompressionMethod, ZipArchiveWriter};
 use rsa::{BigUint, rand_core::OsRng, traits::PublicKeyParts};
 use tempfile::TempDir;
 use topological_sort::TopologicalSort;
 use tracing::{info, info_span};
 use x509_cert::Certificate;
-use zip::{CompressionMethod, DateTime, ZipWriter, write::SimpleFileOptions};

 use crate::{
    cli::{Cli, Command, HelperCli, ListCli, PassSource, ProfileGroup, TestCli},
@@ -97,7 +97,7 @@ fn verify_hash(path: &Path, sha256: &[u8; 32], cancel_signal: &AtomicBool) -> Re
 }

 fn append_avb(
-    file: &mut PSeekFile,
+    file: &File,
    name: &str,
    avb: Avb,
    hash_tree: bool,
@@ -105,7 +105,7 @@ fn append_avb(
    key_avb: &RsaSigningKey,
    cancel_signal: &AtomicBool,
 ) -> Result<()> {
-    let image_size = file.seek(SeekFrom::End(0))?;
+    let image_size = (&*file).seek(SeekFrom::End(0))?;
    let salt = ring::digest::digest(&ring::digest::SHA256, b"avbroot");
    let descriptors = vec![
        if hash_tree {
@@ -127,7 +127,7 @@ fn append_avb(
                reserved: [0u8; 60],
            };

-            descriptor.update(file, file, None, cancel_signal)?;
+            descriptor.update(file, None, cancel_signal)?;

            Descriptor::HashTree(descriptor)
        } else {
@@ -141,8 +141,8 @@ fn append_avb(
                reserved: [0u8; 60],
            };

-            file.rewind()?;
-            descriptor.update(&mut *file, cancel_signal)?;
+            (&*file).rewind()?;
+            descriptor.update(file, cancel_signal)?;

            Descriptor::Hash(descriptor)
        },
@@ -190,7 +190,7 @@ fn append_avb(
        reserved: Default::default(),
    };

-    let eof_size = file.seek(SeekFrom::End(0))?;
+    let eof_size = (&*file).seek(SeekFrom::End(0))?;
    let full_image_size = eof_size
        .checked_add(8192)
        .and_then(|s| padding::round(s, 4096))
@@ -295,7 +295,7 @@ fn create_ramdisk(

 #[allow(clippy::too_many_arguments)]
 fn create_boot_image(
-    file: &mut PSeekFile,
+    file: &File,
    name: &str,
    avb: Avb,
    boot_data: &BootData,
@@ -412,7 +412,7 @@ fn create_boot_image(
        }
    };

-    boot_image.to_writer(&mut *file)?;
+    boot_image.to_writer(file)?;

    append_avb(file, name, avb, false, ota_info, key_avb, cancel_signal)
        .with_context(|| format!("Failed to append AVB metadata for {name}"))?;
@@ -422,7 +422,7 @@ fn create_boot_image(

 #[allow(clippy::too_many_arguments)]
 fn create_dm_verity_image(
-    file: &mut PSeekFile,
+    file: &File,
    name: &str,
    avb: Avb,
    dm_verity_data: DmVerityData,
@@ -433,16 +433,16 @@ fn create_dm_verity_image(
 ) -> Result<()> {
    match dm_verity_data.content {
        DmVerityContent::SystemOtacerts => {
-            file.write_all(b"arbitrary_prefix")?;
+            (&*file).write_all(b"arbitrary_prefix")?;

            let data = otacert::create_zip(cert_ota, OtaCertBuildFlags::empty())?;
-            file.write_all(&data)?;
+            (&*file).write_all(&data)?;

-            file.write_all(b"arbitrary_suffix")?;
+            (&*file).write_all(b"arbitrary_suffix")?;
        }
    }

-    padding::write_zeros(&mut *file, 4096)?;
+    padding::write_zeros(file, 4096)?;

    append_avb(file, name, avb, true, ota_info, key_avb, cancel_signal)
        .with_context(|| format!("Failed to append AVB metadata for {name}"))?;
@@ -451,19 +451,18 @@ fn create_dm_verity_image(
 }

 fn create_vbmeta_image(
-    file: &mut PSeekFile,
+    file: &File,
    name: &str,
    avb: Avb,
    vbmeta_data: &VbmetaData,
-    inputs: &BTreeMap<String, PSeekFile>,
+    inputs: &BTreeMap<String, File>,
    key: &RsaSigningKey,
 ) -> Result<()> {
    let mut descriptors = Vec::new();

    for dep in &vbmeta_data.deps {
-        let reader = inputs[dep].reopen()?;
-        let (child_header, _, _) =
-            avb::load_image(reader).with_context(|| format!("Failed to parse AVB image: {dep}"))?;
+        let (child_header, _, _) = avb::load_image(&inputs[dep])
+            .with_context(|| format!("Failed to parse AVB image: {dep}"))?;

        if child_header.public_key.is_empty() {
            descriptors.extend(child_header.descriptors);
@@ -511,7 +510,7 @@ fn create_partition_images(
    key_avb: &RsaSigningKey,
    cert_ota: &Certificate,
    cancel_signal: &AtomicBool,
-) -> Result<BTreeMap<String, PSeekFile>> {
+) -> Result<BTreeMap<String, File>> {
    let mut topo = TopologicalSort::<&String>::new();

    for (name, partition) in partitions {
@@ -530,14 +529,13 @@ fn create_partition_images(
        };
        let partition = &partitions[name];

-        let mut file = tempfile::tempfile()
-            .map(PSeekFile::new)
+        let file = tempfile::tempfile()
            .with_context(|| format!("Failed to create temp file for {name}"))?;

        match &partition.data {
            Data::Boot(data) => {
                create_boot_image(
-                    &mut file,
+                    &file,
                    name,
                    partition.avb,
                    data,
@@ -550,7 +548,7 @@ fn create_partition_images(
            }
            Data::DmVerity(data) => {
                create_dm_verity_image(
-                    &mut file,
+                    &file,
                    name,
                    partition.avb,
                    *data,
@@ -562,7 +560,7 @@ fn create_partition_images(
                .with_context(|| format!("Failed to create dm-verity image: {name}"))?;
            }
            Data::Vbmeta(data) => {
-                create_vbmeta_image(&mut file, name, partition.avb, data, &files, key_avb)
+                create_vbmeta_image(&file, name, partition.avb, data, &files, key_avb)
                    .with_context(|| format!("Failed to create vbmeta image: {name}"))?;
            }
        }
@@ -576,14 +574,12 @@ fn create_partition_images(
 fn create_payload(
    writer: impl Write,
    partitions: &BTreeMap<String, Partition>,
-    inputs: &BTreeMap<String, PSeekFile>,
+    inputs: &BTreeMap<String, File>,
    ota_info: &OtaInfo,
    profile: &Profile,
    key_ota: &RsaSigningKey,
    cancel_signal: &AtomicBool,
 ) -> Result<(String, u64)> {
-    const COMPRESSION_FACTOR: u32 = 64 * 1024;
-
    let dynamic_partitions_names = partitions
        .iter()
        .filter(|(_, p)| matches!(&p.data, Data::DmVerity(_)))
@@ -591,18 +587,16 @@ fn create_payload(
        .collect::<Vec<_>>();

    let mut payload_partitions = vec![];
-    let mut compressed = BTreeMap::<&String, PSeekFile>::new();
+    let mut compressed = BTreeMap::<&String, File>::new();

    for (name, file) in inputs {
        let writer = tempfile::tempfile()
-            .map(PSeekFile::new)
            .with_context(|| format!("Failed to create temp file for: {name}"))?;

        let vabc_params = if dynamic_partitions_names.contains(name) {
            profile.vabc.map(|v| VabcParams {
                version: v.version,
                algo: v.algo,
-                compression_factor: COMPRESSION_FACTOR,
            })
        } else {
            None
@@ -613,7 +607,9 @@ fn create_payload(

        compressed.insert(name, writer);

-        let is_v3 = profile.vabc.is_some_and(|e| e.version == CowVersion::V3);
+        let is_v3 = profile
+            .vabc
+            .is_some_and(|e| matches!(e.version, CowVersion::V3 { .. }));

        payload_partitions.push(PartitionUpdate {
            partition_name: name.clone(),
@@ -661,10 +657,13 @@ fn create_payload(
                vabc_compression_param: profile.vabc.map(|v| v.algo.to_string()),
                cow_version: profile.vabc.map(|v| match v.version {
                    CowVersion::V2 => 2,
-                    CowVersion::V3 => 3,
+                    CowVersion::V3 { .. } => 3,
                }),
                vabc_feature_set: None,
-                compression_factor: profile.vabc.map(|_| COMPRESSION_FACTOR.into()),
+                compression_factor: profile.vabc.and_then(|v| match v.version {
+                    CowVersion::V2 => v.force_compression_factor.then_some(64 * 1024),
+                    CowVersion::V3 { compression_factor } => Some(compression_factor.into()),
+                }),
            }),
            partial_update: None,
            apex_info: vec![],
@@ -740,40 +739,32 @@ fn create_ota(
        .truncate(true)
        .open(output)
        .with_context(|| format!("Failed to open for writing: {output:?}"))?;
-    let mut zip_writer = match zip_mode {
-        ZipMode::Streaming => {
-            let signing_writer = SigningWriter::new_streaming(raw_writer);
-            ZipWriterWrapper::new_streaming(signing_writer)
-        }
-        ZipMode::Seekable => {
-            let signing_writer = SigningWriter::new_seekable(raw_writer);
-            ZipWriterWrapper::new_seekable(signing_writer)
-        }
+    let signing_writer = match zip_mode {
+        ZipMode::Streaming => SigningWriter::new_streaming(raw_writer),
+        ZipMode::Seekable => SigningWriter::new_seekable(raw_writer),
    };
-    let options = SimpleFileOptions::default()
-        .last_modified_time(DateTime::default())
-        .compression_method(CompressionMethod::Stored)
-        .large_file(false);
+    let mut zip_writer = ZipArchiveWriter::new(signing_writer);

    let mut entries = vec![];
    let mut properties = None;
    let mut payload_metadata_size = None;

    for path in [ota::PATH_OTACERT, ota::PATH_PAYLOAD, ota::PATH_PROPERTIES] {
-        // All remaining entries are written immediately.
-        let offset = zip_writer
-            .start_file(path, options)
+        let (entry_writer, data_config) = zip_writer
+            .new_file(path)
+            .start()
            .with_context(|| format!("Failed to begin new zip entry: {path}"))?;
-        let mut writer = CountingWriter::new(&mut zip_writer);
+        let offset = entry_writer.stream_offset();
+        let mut data_writer = data_config.wrap(entry_writer);

        match path {
            ota::PATH_OTACERT => {
-                crypto::write_pem_cert(Path::new(path), &mut writer, cert_ota)
+                crypto::write_pem_cert(Path::new(path), &mut data_writer, cert_ota)
                    .with_context(|| format!("Failed to write entry: {path}"))?;
            }
            ota::PATH_PAYLOAD => {
                let (p, m) = create_payload(
-                    &mut writer,
+                    &mut data_writer,
                    &profile.partitions,
                    &inputs,
                    ota_info,
@@ -787,15 +778,17 @@ fn create_ota(
                payload_metadata_size = Some(m);
            }
            ota::PATH_PROPERTIES => {
-                writer
+                data_writer
                    .write_all(properties.as_ref().unwrap().as_bytes())
                    .with_context(|| format!("Failed to write payload properties: {path}"))?;
            }
            _ => unreachable!(),
        }

-        // Cannot fail.
-        let size = writer.stream_position()?;
+        let size = data_writer
+            .finish()
+            .and_then(|(w, d)| w.finish(d))
+            .with_context(|| format!("Failed to finalize zip entry: {path}"))?;

        entries.push(ZipEntry {
            path: path.to_owned(),
@@ -832,18 +825,15 @@ fn create_ota(
        spl_downgrade: false,
    };

-    let data_descriptor_size = match zip_mode {
-        ZipMode::Streaming => 16,
-        ZipMode::Seekable => 0,
-    };
+    let next_offset = zip_writer.stream_offset();
+
    ota::add_metadata(
        &entries,
        &mut zip_writer,
        // Offset where next entry would begin.
-        entries.last().map(|e| e.offset + e.size).unwrap() + data_descriptor_size,
+        next_offset,
        &metadata,
        payload_metadata_size.unwrap(),
-        zip_mode,
    )
    .context("Failed to write new OTA metadata")?;

@@ -861,13 +851,19 @@ fn create_ota(
 }

 fn create_fake_magisk(output: &Path) -> Result<()> {
-    let raw_writer =
-        File::create(output).with_context(|| format!("Failed to open for writing: {output:?}"))?;
-    let mut zip_writer = ZipWriter::new(raw_writer);
-    let options = SimpleFileOptions::default().last_modified_time(DateTime::default());
+    let raw_writer = OpenOptions::new()
+        .read(true)
+        .write(true)
+        .create(true)
+        .truncate(true)
+        .open(output)
+        .with_context(|| format!("Failed to open for writing: {output:?}"))?;
+    let mut zip_writer = ZipArchiveWriter::new(raw_writer);
+    let compression_method = CompressionMethod::Deflate;

    for path in [
        "assets/stub.apk",
+        "assets/util_functions.sh",
        "lib/arm64-v8a/libinit-ld.so",
        "lib/arm64-v8a/libmagisk64.so",
        "lib/arm64-v8a/libmagiskinit.so",
@@ -881,13 +877,31 @@ fn create_fake_magisk(output: &Path) -> Result<()> {
        "lib/x86_64/libmagisk64.so",
        "lib/x86_64/libmagiskinit.so",
    ] {
-        zip_writer.start_file(path, options)?;
-        write!(zip_writer, "dummy contents for {path}")?;
+        let (entry_writer, data_config) = zip_writer
+            .new_file(path)
+            .compression_method(compression_method)
+            .start()
+            .with_context(|| format!("Failed to begin new zip entry: {path}"))?;
+        let compressed_writer = zip::compressed_writer(entry_writer, compression_method)
+            .with_context(|| format!("Failed to begin new zip entry: {path}"))?;
+        let mut data_writer = data_config.wrap(compressed_writer);
+
+        if path == "assets/util_functions.sh" {
+            // avbroot looks for the version number in this file.
+            data_writer.write_all(b"MAGISK_VER_CODE=27000\n")?;
+        } else {
+            write!(data_writer, "dummy contents for {path}")?;
+        }
+
+        data_writer
+            .finish()
+            .and_then(|(w, d)| w.finish()?.finish(d))?;
    }

-    // avbroot looks for the version number in this file.
-    zip_writer.start_file("assets/util_functions.sh", options)?;
-    zip_writer.write_all(b"MAGISK_VER_CODE=27000\n")?;
+    let raw_writer = zip_writer.finish()?;
+
+    zip::make_non_streaming(raw_writer)
+        .with_context(|| format!("Failed to convert to non-streaming zip: {output:?}"))?;

    Ok(())
 }
@@ -1141,7 +1155,7 @@ fn clean_boot_image_certs(path: &Path, cancel_signal: &AtomicBool) -> Result<()>
        .iter_mut()
        .find(|e| e.path == b"system/etc/security/otacerts.zip")
    {
-        let zip_writer = ZipWriter::new(Cursor::new(Vec::new()));
+        let zip_writer = ZipArchiveWriter::new(Cursor::new(Vec::new()));
        let empty_zip = zip_writer.finish()?.into_inner();

        entry.data = CpioEntryData::Data(empty_zip);
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023 Andrew Gunnerson
+// SPDX-FileCopyrightText: 2023-2025 Andrew Gunnerson
 // SPDX-License-Identifier: GPL-3.0-only

 #[cfg(not(windows))]
@@ -7,7 +7,7 @@ mod fuzz {

    use avbroot::{
        format::fec::FecImage,
-        stream::{FromReader, SharedCursor, WriteZerosExt},
+        stream::{FromReader, MutexFile, UserPosFile, WriteZerosExt},
    };
    use honggfuzz::fuzz;

@@ -18,12 +18,14 @@ mod fuzz {

                let reader = Cursor::new(data);
                if let Ok(fec) = FecImage::from_reader(reader) {
-                    let mut input = SharedCursor::new();
+                    let input = MutexFile::new(Cursor::new(Vec::new()));

                    // Allow verify() to get further, but don't blow up the host
                    // with excessive memory usage.
                    if fec.data_size < 64 * 1024 * 1024 {
-                        input.write_zeros_exact(fec.data_size).unwrap();
+                        UserPosFile::new(&input)
+                            .write_zeros_exact(fec.data_size)
+                            .unwrap();
                    }

                    let _ = fec.verify(&input, &cancel_signal);
Author	SHA1	Message	Date
Andrew Gunnerson	8f71b61b21	Version 3.21.0 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 21:18:59 -04:00
Andrew Gunnerson	fa8d9eb58c	CHANGELOG.md: Add entry for PR #505 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 20:15:19 -04:00
Andrew Gunnerson	39afcf485f	Fix clippy lints Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 20:14:52 -04:00
Andrew Gunnerson	a3eb8284c8	CHANGELOG.md: Add entry for PR #504 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 20:08:01 -04:00
Andrew Gunnerson	e2708d39dd	format/payload: Make compression factor required only for CoW v3 It turns out that even though newer versions of delta_generator set this field for CoW v2 (unused), older versions did not. Fixes: #493 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 20:03:33 -04:00
Andrew Gunnerson	a5f13826e7	CHANGELOG.md: Add entry for PR #503 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 19:21:42 -04:00
Andrew Gunnerson	963456c194	patch/boot: Replace function pointers with opener trait Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 19:19:55 -04:00
Andrew Gunnerson	842a2feb88	CHANGELOG.md: Add entry for PR #502 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 19:02:00 -04:00
Andrew Gunnerson	8bb1f771af	format/payload: Remove unnecessary function pointer in extract_images() The list of output files that are needed are known beforehand. There's no need to dynamically open them. Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 18:47:05 -04:00
Andrew Gunnerson	ab51654dad	CHANGELOG.md: Add entry for PR #498 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 18:43:26 -04:00
Andrew Gunnerson	d75b87d3df	Update dependencies The e2e checksums were updated because the new lzma-rust2 version has slight differences in compression ratio. Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 18:18:39 -04:00
Andrew Gunnerson	73e0404662	CHANGELOG.md: Add entry for PR #501 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 18:18:27 -04:00
Andrew Gunnerson	ebb4f18add	Use try_for_each where possible (round 2) Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 18:17:46 -04:00
Andrew Gunnerson	bee8d80df0	CHANGELOG.md: Add entry for PR #500 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 18:12:08 -04:00
Andrew Gunnerson	fdb19e3b97	format/payload: Use dynamic dispatch for large functions Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 17:54:05 -04:00
Andrew Gunnerson	cef29fd280	CHANGELOG.md: Add entry for PR #499 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 17:18:00 -04:00
Andrew Gunnerson	58155513af	format/payload: Fix out-of-order multithreaded writes This was a regression from `d874921a69`. extract_images()'s open_output parameter was requesting a WriteSeek instead of a WriteAt, so it received multiple instances of Arc<File> all with the same underlying File (and file offset). Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-23 17:08:23 -04:00
Andrew Gunnerson	01cdd0b0d3	CHANGELOG.md: Add entry for PR #497 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-22 22:37:07 -04:00
Andrew Gunnerson	e39d023855	format/cpio: Fix integer underflow panic in debug builds Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-22 22:35:48 -04:00
Andrew Gunnerson	05c86af298	CHANGELOG.md: Add entry for PR #496 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-22 22:21:45 -04:00
Andrew Gunnerson	759ed7fae5	Use try_for_each where possible Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-22 22:11:32 -04:00
Andrew Gunnerson	f6aac1c12f	deny.toml: Remove unused git repo URL Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-22 22:07:31 -04:00
Andrew Gunnerson	e5b754c786	CHANGELOG.md: Add entry for PR #495 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-22 22:07:31 -04:00
Andrew Gunnerson	d874921a69	Replace file reopen concept with ReadAt/WriteAt traits File reopening was conflating ownership of file-like types with the fact that they support parallel reads and writes at arbitrary offsets. The Reopen trait has now been replaced with ReadAt and WriteAt traits, which are implemented for types that support parallel I/O. If a type compatible with the standard Read/Write/Seek traits is needed, a new UserPosFile type can act as the bridge by storing its own userspace file offset. For the opposite bridge, there's MutexFile, which implements ReadAt/WriteAt by using locks to make the operations sequential. This is only really used in the tests though. This eliminates the need for the PSeekFile and SharedCursor types. The standard File and Cursor types can be used instead, and if shared ownership is needed, Arc can be used. Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-22 22:07:11 -04:00
Andrew Gunnerson	390dce5f0c	CHANGELOG.md: Add entry for PR #492 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-21 18:57:08 -04:00
Andrew Gunnerson	6d939bda25	Use seek_relative where possible This will not make a meaningful performance difference for our use case, but does not make things any more complex either. Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-21 18:55:21 -04:00
Andrew Gunnerson	a40d6ea379	CHANGELOG.md: Add entry for PR #489 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-21 00:50:00 -04:00
Andrew Gunnerson	7d0bb378a6	Switch to rawzip crate for zip file handling rawzip is a lower-level zip file library that is much more suited for avbroot's use case. Its speed improvements aren't too important since OTAs only have a handful of files, but it is a simpler layer of abstraction and exposes more about zip file internals. We also no longer need to maintain a perpetual fork of the zip library. The only caveat is that rawzip (much like avbroot) is built around writing zip files in a streaming fashion. To support `--zip-mode seekable`, the output file is post-processed to copy the relevant data descriptor fields to the local header. The unused data descriptors remain in the file to avoid needing to shift file data, but this does not violate the spec and Android's libziparchive accepts it just fine. Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-20 21:12:27 -04:00
Andrew Gunnerson	3ed38b8d29	ci.yml: Set RUSTDOCFLAGS to statically link doctests Prior to Rust 1.89, these tests were just skipped when cross-compiling. Now, they are actually compiled and ran. Unfortunately, doctests don't use the normal RUSTFLAGS environment variable, so we also need to set RUSTDOCFLAGS or else the resulting dynamically linked executable will fail to run on a non-Android host. Upstream change: https://github.com/rust-lang/cargo/pull/15462 Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>	2025-08-19 20:13:56 -04:00
Ivan	0717981d62	README.ru.md: Update translation * https://github.com/chenxiaolong/avbroot/commit/f393d7adc42e43b2857a60c3b5fd404b14f042c4 * https://github.com/chenxiaolong/avbroot/commit/2f964bf113512bd7ff33eb3e47116305a262e9fc * https://github.com/chenxiaolong/avbroot/commit/a2fe6fc9d882d4fd955d03b3a2046c5a41d5840c * https://github.com/chenxiaolong/avbroot/commit/2683781737230b98172de335a6597363c6d71ff2 Signed-off-by: Ivan <reddxae@proton.me>	2025-08-14 12:20:38 +03:00
Ivan	556f86e4df	README.md: Use "device" as a generic reference, clarifying & style improvements * Use "device" as a generic reference instead of "phone" throughout the project description as more than just phones can support custom AVB functionality. * Finalize the clarification on signing key generation in the initial setup section introduced by commit https://github.com/chenxiaolong/avbroot/commit/2f964bf113512bd7ff33eb3e47116305a262e9fc. * The "warning" in the merging snapshots section is marked in bold and uppercase, aligning with the rest of the text, while less important "notes" don't stand out in the same way. Signed-off-by: Ivan <reddxae@proton.me>	2025-08-14 12:19:38 +03:00