fs: validate copyFile paths in the existing C++ binding

[anonrig]

Move getValidatedPath, file URL conversion, and NUL checks into the existing C++ binding.copyFile. fs.copyFile, fs.copyFileSync, and fs.promises.copyFile all pass the original arguments through.

There is no second copyFileSync binding. JavaScript only does VFS dispatch (still before validation). The copy itself uses uv_fs_copyfile, so COPYFILE_EXCL / FICLONE / FICLONE_FORCE, mode/timestamp preservation, and UV error shapes (syscall: 'copyfile', path / dest) stay the same.

This also fixes a crash in the C++ FileURLToPath helper: ERR_INVALID_FILE_URL_HOST used a format string without %s, which aborted on file URLs with a hostname. That path is now reachable from copyFile / copyFileSync.

Performance

Same-binary comparison of the old JS getValidatedPath + binding.copyFile path vs the unified C++-validated binding.copyFile (n=10000, 9 interleaved repeats, Release):

case	old	C++	change
valid copy	60.8 µs/op	61.1 µs/op	~same
missing src (ENOENT)	5.52 µs/op	5.39 µs/op	~2% faster
invalid type	8.04 µs/op	3.92 µs/op	~51% faster
file URL	60.0 µs/op	60.2 µs/op	~same

benchmark/fs/bench-copyFileSync.js (n=10000) is dominated by uv_fs_copyfile I/O on valid (~16k ops/sec) and by ENOENT on invalid (~260k ops/sec). Those cases stay within a few percent of the old path. The win is validation-bound input (wrong type). Because validation now lives in binding.copyFile, the callback and promises entry points get the same path — not only copyFileSync.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Tests

• test/parallel/test-fs-copyfile.js (Buffer, Uint8Array, file: URL, non-file URL, encoded slashes, file URL host; callback copyFile also throws ERR_INVALID_URL_SCHEME)
• test/parallel/test-fs-copyfile-respect-permissions.js
• test/parallel/test-fs-null-bytes.js
• test/parallel/test-fs-error-messages.js
• test/parallel/test-permission-fs-read.js / test-permission-fs-write.js
• VFS copyFile / copyFileSync tests

[nodejs-github-bot]

Review requested:

• @nodejs/url

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.12%. Comparing base (cf30b2e) to head (0fcda9b).
⚠️ Report is 69 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_file.cc	70.52%	10 Missing and 18 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65376      +/-   ##
==========================================
+ Coverage   90.11%   90.12%   +0.01%     
==========================================
  Files         752      752              
  Lines      251861   252394     +533     
  Branches    47365    47457      +92     
==========================================
+ Hits       226955   227478     +523     
+ Misses      16238    16217      -21     
- Partials     8668     8699      +31     

Files with missing lines	Coverage Δ
lib/fs.js	98.39% <100.00%> (+0.02%)	⬆️
lib/internal/fs/promises.js	92.50% <100.00%> (-0.50%)	⬇️
src/node_url.cc	80.70% <100.00%> (+2.98%)	⬆️
src/node_file.cc	73.96% <70.52%> (-0.27%)	⬇️

... and 69 files with indirect coverage changes

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[mcollina]

I don't understand this. copyFile seems already implemented in C++.

[anonrig]

I don't understand this. copyFile seems already implemented in C++.

Except getValidatedPath @mcollina

[mcollina]

Then why keep both methods? Can't we just fix copyFile and update all usage of that?

[anonrig]

@mcollina you're right — no need for a second binding.

getValidatedPath, file URL conversion, and NUL checks now live in the existing C++ copyFile. fs.copyFile, fs.copyFileSync, and fs.promises.copyFile all call that one method with the original arguments. The extra copyFileSync binding is gone.

VFS dispatch is still in JS and still runs first.

[mcollina]

lgtm

Please update the PR description

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/76111/

[jasnell]

ToV8Value?

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/76168/

[mcollina]

The first commit needs some changes, as it does not reflect what this PR does anymore.
The second commit has metadata issues.