src: consolidate C++ ReadFileSync/WriteFileSync utilities #61662

joyeecheung · 2026-02-03T20:19:17Z

This patch moves ReadFileSync and WriteFileSync from src/util.cc to src/node_file_utils.cc, consolidates the implementation to reuse code, and adds a few more enhancements:

For ReadFileSync:

Use fstat-based pre-allocation to minimize buffer resizing and repeated reads for bigger files.
Handle various potential overflows in size conversions.
Handle fallback for 0-byte special files.

For WriteFileSync:

Handle potential partial writes for big enough files and support non-seekable files (with -1 as offset).
Handle 0-byte writes correctly.

In both cases, this now avoids hard aborts and return error code for the caller to handle as much as possible, except std::vector<char> ReadFileSync(FILE* fp) which is part of the embedder API.

This patch uses the new ReadFileSync to address a TODO in node_sea.bin.cc.

Some numbers from --build-sea (note that most of the time is spent on parsing the executable and building the SEA, but even so there's a measurable difference just from the file I/O because the binary is ~120MB).

$ hyperfine "out/Release/node --build-sea sea-config.json" "./node_main --build-sea sea-config.json" --warmup 5
Benchmark 1: out/Release/node --build-sea sea-config.json
  Time (mean ± σ):      1.696 s ±  0.040 s    [User: 1.509 s, System: 0.173 s]
  Range (min … max):    1.651 s …  1.756 s    10 runs

Benchmark 2: ./node_main --build-sea sea-config.json
  Time (mean ± σ):      1.730 s ±  0.030 s    [User: 1.530 s, System: 0.183 s]
  Range (min … max):    1.681 s …  1.787 s    10 runs

Summary
  out/Release/node --build-sea sea-config.json ran
    1.02 ± 0.03 times faster than ./node_main --build-sea sea-config.json

This patch moves `ReadFileSync` and `WriteFileSync` from `src/util.cc` to `src/node_file_utils.cc`, consolidates the implementation to reuse code, and adds a few more enhancements: For `ReadFileSync`: - Use fstat-based pre-allocation to minimize buffer resizing and repeated reads for bigger files. - Handle various potential overflows in size conversions. - Handle fallback for 0-byte special files. For `WriteFileSync`: - Handle potential partial writes for big enough files and support non-seekable files (with -1 as offset). - Handle 0-byte writes correctly. In both cases, this now avoids hard aborts and return error code for the caller to handle as much as possible, except `std::vector<char> ReadFileSync(FILE* fp)` which is part of the embedder API. This patch uses the new `ReadFileSync` to address a TODO in node_sea.bin.cc.

nodejs-github-bot · 2026-02-03T20:19:22Z

Review requested:

@nodejs/gyp
@nodejs/single-executable

joyeecheung · 2026-02-03T20:26:48Z

cc @nodejs/cpp-reviewers

nodejs-github-bot · 2026-02-03T20:56:23Z

CI: https://ci.nodejs.org/job/node-test-pull-request/71186/

codecov · 2026-02-03T22:04:51Z

Codecov Report

❌ Patch coverage is 62.85714% with 52 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.72%. Comparing base (8e41b8d) to head (48ed3ef).
⚠️ Report is 42 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_file_utils.cc	62.31%	30 Missing and 22 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61662      +/-   ##
==========================================
- Coverage   89.74%   89.72%   -0.03%     
==========================================
  Files         674      675       +1     
  Lines      204348   204472     +124     
  Branches    39271    39290      +19     
==========================================
+ Hits       183396   183460      +64     
- Misses      13262    13303      +41     
- Partials     7690     7709      +19

Files with missing lines	Coverage Δ
src/node_internals.h	`82.35% <ø> (ø)`
src/node_sea_bin.cc	`41.51% <100.00%> (-0.22%)`	⬇️
src/util.cc	`87.44% <ø> (+1.34%)`	⬆️
src/util.h	`90.09% <ø> (ø)`
src/node_file_utils.cc	`62.31% <62.31%> (ø)`

... and 35 files with indirect coverage changes

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Qard

LGTM. A few small code quality improvement ideas, but I'm fine landing as-is. These are just minor suggestions to simplify things slightly. 🙂

src/node_file_utils.cc

Co-authored-by: Stephen Belanger <[email protected]>

joyeecheung · 2026-02-05T01:11:48Z

Thanks for the suggestion. @Qard @RafaelGSS Can you take a look again?

nodejs-github-bot · 2026-02-05T02:12:45Z

CI: https://ci.nodejs.org/job/node-test-pull-request/71197/

nodejs-github-bot · 2026-02-05T13:16:42Z

CI: https://ci.nodejs.org/job/node-test-pull-request/71203/

nodejs-github-bot · 2026-02-07T00:45:41Z

CI: https://ci.nodejs.org/job/node-test-pull-request/71225/

This patch moves `ReadFileSync` and `WriteFileSync` from `src/util.cc` to `src/node_file_utils.cc`, consolidates the implementation to reuse code, and adds a few more enhancements: For `ReadFileSync`: - Use fstat-based pre-allocation to minimize buffer resizing and repeated reads for bigger files. - Handle various potential overflows in size conversions. - Handle fallback for 0-byte special files. For `WriteFileSync`: - Handle potential partial writes for big enough files and support non-seekable files (with -1 as offset). - Handle 0-byte writes correctly. In both cases, this now avoids hard aborts and return error code for the caller to handle as much as possible, except `std::vector<char> ReadFileSync(FILE* fp)` which is part of the embedder API. This patch uses the new `ReadFileSync` to address a TODO in node_sea.bin.cc. PR-URL: #61662 Reviewed-By: Rafael Gonzaga <[email protected]> Reviewed-By: Stephen Belanger <[email protected]> Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: James M Snell <[email protected]>

nodejs-github-bot · 2026-02-07T02:38:59Z

Landed in 9bc369f...3ab9dd8

This patch moves `ReadFileSync` and `WriteFileSync` from `src/util.cc` to `src/node_file_utils.cc`, consolidates the implementation to reuse code, and adds a few more enhancements: For `ReadFileSync`: - Use fstat-based pre-allocation to minimize buffer resizing and repeated reads for bigger files. - Handle various potential overflows in size conversions. - Handle fallback for 0-byte special files. For `WriteFileSync`: - Handle potential partial writes for big enough files and support non-seekable files (with -1 as offset). - Handle 0-byte writes correctly. In both cases, this now avoids hard aborts and return error code for the caller to handle as much as possible, except `std::vector<char> ReadFileSync(FILE* fp)` which is part of the embedder API. This patch uses the new `ReadFileSync` to address a TODO in node_sea.bin.cc. PR-URL: #61662 Reviewed-By: Rafael Gonzaga <[email protected]> Reviewed-By: Stephen Belanger <[email protected]> Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: James M Snell <[email protected]>

This MR contains the following updates: | Package | Update | Change | |---|---|---| | [node](https://nodejs.org) ([source](https://github.com/nodejs/node)) | patch | `25.6.0` → `25.6.1` | MR created with the help of [el-capitano/tools/renovate-bot](https://gitlab.com/el-capitano/tools/renovate-bot). **Proposed changes to behavior should be submitted there as MRs.** --- ### Release Notes <details> <summary>nodejs/node (node)</summary> ### [`v25.6.1`](https://github.com/nodejs/node/releases/tag/v25.6.1): 2026-02-10, Version 25.6.1 (Current), @aduh95 [Compare Source](nodejs/node@v25.6.0...v25.6.1) ##### Notable Changes - \[[`47df4328d7`](nodejs/node@47df4328d7)] - **build,deps**: replace `cjs-module-lexer` with `merve` (Yagiz Nizipli) [#61456](nodejs/node#61456) ##### Commits - \[[`47df4328d7`](nodejs/node@47df4328d7)] - **build,deps**: replace cjs-module-lexer with merve (Yagiz Nizipli) [#61456](nodejs/node#61456) - \[[`a727054503`](nodejs/node@a727054503)] - **deps**: upgrade npm to 11.9.0 (npm team) [#61685](nodejs/node#61685) - \[[`c78c49ed6b`](nodejs/node@c78c49ed6b)] - **deps**: update amaro to 1.1.7 (Node.js GitHub Bot) [#61730](nodejs/node#61730) - \[[`4790816d9b`](nodejs/node@4790816d9b)] - **deps**: update minimatch to 10.1.2 (Node.js GitHub Bot) [#61732](nodejs/node#61732) - \[[`8c71740e8a`](nodejs/node@8c71740e8a)] - **deps**: update undici to 7.21.0 (Node.js GitHub Bot) [#61683](nodejs/node#61683) - \[[`e559ef6ab1`](nodejs/node@e559ef6ab1)] - **deps**: update googletest to [`56efe39`](nodejs/node@56efe39) (Node.js GitHub Bot) [#61605](nodejs/node#61605) - \[[`300de2bb5a`](nodejs/node@300de2bb5a)] - **deps**: update amaro to 1.1.6 (Node.js GitHub Bot) [#61603](nodejs/node#61603) - \[[`e71e9505ef`](nodejs/node@e71e9505ef)] - **dns**: fix Windows SRV ECONNREFUSED by adjusting c-ares fallback detection (notvivek12) [#61453](nodejs/node#61453) - \[[`439b816bc7`](nodejs/node@439b816bc7)] - **doc**: clarify EventEmitter error handling in threat model (Matteo Collina) [#61701](nodejs/node#61701) - \[[`c1c6641f23`](nodejs/node@c1c6641f23)] - **doc**: mention default option for test runner env (Steven) [#61659](nodejs/node#61659) - \[[`41ec451f98`](nodejs/node@41ec451f98)] - **doc**: fix --inspect security warning section (Tim Perry) [#61675](nodejs/node#61675) - \[[`bb90ef2356`](nodejs/node@bb90ef2356)] - **doc**: document `url.format(urlString)` as deprecated under DEP0169 (René) [#61644](nodejs/node#61644) - \[[`513df82e6f`](nodejs/node@513df82e6f)] - **doc**: update to Visual Studio 2026 manual install (Mike McCready) [#61655](nodejs/node#61655) - \[[`9409d30736`](nodejs/node@9409d30736)] - **doc**: deprecation add more codemod (Augustin Mauroy) [#61642](nodejs/node#61642) - \[[`75a7a67151`](nodejs/node@75a7a67151)] - **doc**: fix grammatical error in README.md (ayj8201) [#61653](nodejs/node#61653) - \[[`821e59e884`](nodejs/node@821e59e884)] - **doc**: correct tools README Boxstarter link (Mike McCready) [#61638](nodejs/node#61638) - \[[`4998f539a0`](nodejs/node@4998f539a0)] - **doc**: update `server.dropMaxConnection` link (YuSheng Chen) [#61584](nodejs/node#61584) - \[[`9383ac4ab7`](nodejs/node@9383ac4ab7)] - **http**: implement slab allocation for HTTP header parsing (Mert Can Altin) [#61375](nodejs/node#61375) - \[[`e90eb1d561`](nodejs/node@e90eb1d561)] - **meta**: persist sccache daemon until end of build workflows (René) [#61639](nodejs/node#61639) - \[[`ade36ac367`](nodejs/node@ade36ac367)] - **meta**: bump github/codeql-action from 4.31.9 to 4.32.0 (dependabot\[bot]) [#61622](nodejs/node#61622) - \[[`26638bd67f`](nodejs/node@26638bd67f)] - **meta**: bump step-security/harden-runner from 2.14.0 to 2.14.1 (dependabot\[bot]) [#61621](nodejs/node#61621) - \[[`eaa9a96cb6`](nodejs/node@eaa9a96cb6)] - **meta**: bump actions/setup-python from 6.1.0 to 6.2.0 (dependabot\[bot]) [#61627](nodejs/node#61627) - \[[`fd98187828`](nodejs/node@fd98187828)] - **meta**: bump cachix/cachix-action (dependabot\[bot]) [#61626](nodejs/node#61626) - \[[`820c1d021c`](nodejs/node@820c1d021c)] - **meta**: bump actions/setup-node from 6.1.0 to 6.2.0 (dependabot\[bot]) [#61625](nodejs/node#61625) - \[[`72a4136bd5`](nodejs/node@72a4136bd5)] - **meta**: bump actions/cache from 5.0.1 to 5.0.3 (dependabot\[bot]) [#61624](nodejs/node#61624) - \[[`e3ef6cb3bc`](nodejs/node@e3ef6cb3bc)] - **meta**: bump peter-evans/create-pull-request from 8.0.0 to 8.1.0 (dependabot\[bot]) [#61623](nodejs/node#61623) - \[[`020a836202`](nodejs/node@020a836202)] - **meta**: bump actions/stale from 10.1.0 to 10.1.1 (dependabot\[bot]) [#61620](nodejs/node#61620) - \[[`0df72f07c8`](nodejs/node@0df72f07c8)] - **meta**: bump actions/checkout from 6.0.1 to 6.0.2 (dependabot\[bot]) [#61619](nodejs/node#61619) - \[[`d147c08b83`](nodejs/node@d147c08b83)] - **module**: do not invoke resolve hooks twice for imported cjs (Joyee Cheung) [#61529](nodejs/node#61529) - \[[`a2843f8556`](nodejs/node@a2843f8556)] - **net**: defer synchronous destroy calls in internalConnect (RajeshKumar11) [#61658](nodejs/node#61658) - \[[`7fb7030781`](nodejs/node@7fb7030781)] - **repl**: fix flaky test-repl-programmatic-history (Matteo Collina) [#61614](nodejs/node#61614) - \[[`d4c9b5cf5b`](nodejs/node@d4c9b5cf5b)] - **sqlite**: avoid extra copy for large text binds (Ali Hassan) [#61580](nodejs/node#61580) - \[[`aa1b3661d9`](nodejs/node@aa1b3661d9)] - **sqlite**: use DictionaryTemplate for run() result (Mert Can Altin) [#61432](nodejs/node#61432) - \[[`9c8ad7e881`](nodejs/node@9c8ad7e881)] - **src**: elide heap allocation in structured clone implementation (Anna Henningsen) [#61703](nodejs/node#61703) - \[[`c4ecfef93d`](nodejs/node@c4ecfef93d)] - **src**: use simdutf for one-byte string UTF-8 write in stringBytes (Mert Can Altin) [#61696](nodejs/node#61696) - \[[`28905b9734`](nodejs/node@28905b9734)] - **src**: consolidate C++ ReadFileSync/WriteFileSync utilities (Joyee Cheung) [#61662](nodejs/node#61662) - \[[`e90cec2f69`](nodejs/node@e90cec2f69)] - **test**: restraint version replacement pattern in snapshots (Chengzhong Wu) [#61748](nodejs/node#61748) - \[[`adce20c0a1`](nodejs/node@adce20c0a1)] - **test**: print stack immediately avoiding GC interleaving (Chengzhong Wu) [#61699](nodejs/node#61699) - \[[`7643bc8999`](nodejs/node@7643bc8999)] - **test**: fix case-insensitive path matching on Windows (Matteo Collina) [#61682](nodejs/node#61682) - \[[`23d1ecf66f`](nodejs/node@23d1ecf66f)] - **test**: fix flaky test-performance-eventloopdelay (Matteo Collina) [#61629](nodejs/node#61629) - \[[`99012a88ed`](nodejs/node@99012a88ed)] - **test**: remove duplicate wpt tests (Filip Skokan) [#61617](nodejs/node#61617) - \[[`a8b32b8ce1`](nodejs/node@a8b32b8ce1)] - **test**: fix race condition in watch mode tests (Matteo Collina) [#61615](nodejs/node#61615) - \[[`086a5a5a25`](nodejs/node@086a5a5a25)] - **test**: update WPT for url to [`e3c46fd`](nodejs/node@e3c46fdf55) (Node.js GitHub Bot) [#61602](nodejs/node#61602) - \[[`f0574fd419`](nodejs/node@f0574fd419)] - **test**: use the skipIfNoWatch() utility function (Luigi Pinca) [#61531](nodejs/node#61531) - \[[`b064ddc221`](nodejs/node@b064ddc221)] - **test**: unify assertSnapshot common patterns (Chengzhong Wu) [#61590](nodejs/node#61590) - \[[`17122e521b`](nodejs/node@17122e521b)] - **test\_runner**: fix test enqueue when test file has syntax error (Edy Silva) [#61573](nodejs/node#61573) - \[[`bad3f02dd9`](nodejs/node@bad3f02dd9)] - **tools**: enforce removal of `lts-watch-*` labels on release proposals (Antoine du Hamel) [#61672](nodejs/node#61672) - \[[`a8f33fd6bd`](nodejs/node@a8f33fd6bd)] - **tools**: use ubuntu-slim runner in meta GitHub Actions (Tierney Cyren) [#61663](nodejs/node#61663) - \[[`c843e447ca`](nodejs/node@c843e447ca)] - **tools**: test `--shared-merve` in `test-shared` workflow (Antoine du Hamel) [#61649](nodejs/node#61649) - \[[`2fedc03f96`](nodejs/node@2fedc03f96)] - **tools**: update OpenSSL to 3.5.5 in `test-shared` (Antoine du Hamel) [#61551](nodejs/node#61551) - \[[`1c1db94670`](nodejs/node@1c1db94670)] - **tools,win**: upgrade install additional tools to Visual Studio 2026 (Mike McCready) [#61562](nodejs/node#61562) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Enabled. ♻ **Rebasing**: Whenever MR is behind base branch, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this MR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this MR, check this box --- This MR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).

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fixup! src: consolidate C++ ReadFileSync/WriteFileSync utilities

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Co-authored-by: Stephen Belanger <[email protected]>

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