buffer: remove unreachable overflow check in atob

[haramj]

This commit resolves a TODO comment in lib/buffer.js by changing the error thrown by atob() during a potential overflow condition.

Modified lib/buffer.js to instantiate and throw new ERR_INVALID_ARG_VALUE('input', result, 'The string to be decoded is too long.'); for the overflow case (result === -3).

This change makes the atob implementation more robust and developer-friendly.
@anonrig

->

The case for a result of -3 was intended to handle a potential
buffer overflow error. However, the underlying C++ implementation using
simdutf::base64_to_binary does not perform bounds-checking and therefore
can never return an OUTPUT_BUFFER_TOO_SMALL error.

This makes the case -3: block unreachable code. This commit removes
the dead code for correctness and clarity.

[Renegade334]

simdutf::base64_to_binary can never return OUTPUT_BUFFER_TOO_SMALL, as it doesn't perform bounds-checking of its target. This should just be removed in favour of an assertion in case of an unrecognised error.

[haramj]

simdutf::base64_to_binary can never return OUTPUT_BUFFER_TOO_SMALL, as it doesn't perform bounds-checking of its target. This should just be removed in favour of an assertion in case of an unrecognised error.
@Renegade334 I've pushed a new commit. Please let me know if any other changes are needed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.57%. Comparing base (b13f24c) to head (f5c78ba).
⚠️ Report is 34 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #60161 +/- ##
==========================================
+ Coverage 88.53% 88.57% +0.03% 
==========================================
Files 703 704 +1 Lines 207997 208125 +128 Branches 40015 40012 -3 ==========================================
+ Hits 184150 184338 +188 + Misses 15864 15815 -49 + Partials 7983 7972 -11 

Files with missing lines	Coverage Δ
lib/buffer.js	100.00% <100.00%> (ø)

... and 51 files with indirect coverage changes

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[haramj]

@nodejs/buffer please take a look at this PR when you have some time?

[Renegade334]

I think the comment at the corresponding location in the C++ source should be changed to match:

node/src/node_buffer.cc

Lines 1470 to 1477 in be7ea27

	// Default value is: "possible overflow"
	int32_t error_code = -3;
	if (result.error == simdutf::error_code::INVALID_BASE64_CHARACTER) {
	error_code = -2;
	} elseif (result.error == simdutf::error_code::BASE64_INPUT_REMAINDER) {
	error_code = -1;
	}

Just needs to comment that if the error code case is not recognised, then the function will return the "unrecognised error" value -3 to JS.

[haramj]

I think the comment at the corresponding location in the C++ source should be changed to match:

node/src/node_buffer.cc

Lines 1470 to 1477 in be7ea27

	// Default value is: "possible overflow"
	int32_t error_code = -3;
	if (result.error == simdutf::error_code::INVALID_BASE64_CHARACTER) {
	error_code = -2;
	} elseif (result.error == simdutf::error_code::BASE64_INPUT_REMAINDER) {
	error_code = -1;
	}

Just needs to comment that if the error code case is not recognised, then the function will return the "unrecognised error" value -3 to JS.

Thanks, updated the C++ comments to describe -3 as the unrecognized simdutf error value returned to JS.

[haramj]

@anonrig Could you also take a look since this addresses the atob() TODO? Thanks!

[haramj]

It looks like the Jenkins failures are due to flaky tests rather than issues introduced by this PR.
Could someone please re-run the CI? thanks

[haramj]

The remaining failures appear to be unrelated flaky CI issues. Since all feedback has been addressed, would it be possible to move this PR forward when CI allows?

Thank you

[haramj]

@Renegade334@anonrig@gurgunday Sorry for the ping, but when you have a chance, could you please check the failing tests and re-run the CI if the failures are unrelated to this PR? Thanks!

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/74527/

[richardlau]

CI failures will need a rebase to fix. Since this PR is from October, it is being detected as Node.js 25 which causes the wrong compiler (gcc 12) to be used (should be clang): https://github.com/nodejs/node/blob/ca418cc9a648bb757a41a0dd3a16b15f98b3c46c/src/node_version.h#L25-L27

[haramj]

CI failures will need a rebase to fix. Since this PR is from October, it is being detected as Node.js 25 which causes the wrong compiler (gcc 12) to be used (should be clang):

https://github.com/nodejs/node/blob/ca418cc9a648bb757a41a0dd3a16b15f98b3c46c/src/node_version.h#L25-L27

Thanks for the update. I’ll rebase the PR and re-run CI

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/74547/

[richardlau]

Landed in 14eccf3.