checksum: handle stdin before directory checks

[wtcpython]

Fixes #13390.

Checksum computation checked whether each operand was a directory before handling - as standard input. As a result, a literal ./- directory caused implicit or explicit stdin input to fail.

Handle - before filesystem checks so it remains stdin regardless of entries in the working directory. Extend the existing sha256sum stdin test with a - directory regression fixture.

[HackingRepo]

@wtcpython that is already fixed, uutils 0.8.0 is old the issue already fixed

relunsec@relunsec:~/software/coreutils/target/debug$ ./printf x | ./sha256sum
2d711642b726b04401627ca9fbac32f5c8530fb1903cc4db02258717921a4881  -
relunsec@relunsec:~/software/coreutils/target/debug$ 

please close that pr

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/cut/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/tail-n0f (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/rm/many-dir-entries-vs-OOM is now passing!

[RenjiSann]

Please make a separate test for that.
Also, can you replicate the test on other test_*sum.rs files ? (though we should ideally unify theses somehow)

[wtcpython]

Done. I moved the regression coverage into a separate test and added corresponding tests for b2sum, cksum, md5sum, sha1sum, sha224sum, sha256sum, sha384sum, and sha512sum.

I left sum unchanged because it does not use uu_checksum_common::perform_checksum_computation and is not affected by this issue.

[RenjiSann]

@wtcpython that is already fixed, uutils 0.8.0 is old the issue already fixed

relunsec@relunsec:~/software/coreutils/target/debug$ ./printf x | ./sha256sum
2d711642b726b04401627ca9fbac32f5c8530fb1903cc4db02258717921a4881  -
relunsec@relunsec:~/software/coreutils/target/debug$ 

please close that pr

Strange that it's not fixed on my side 🤔

$ ./target/debug/sha256sum
sha256sum: -: Is a directory

[codspeed-hq]

Merging this PR will not alter performance

✅ 339 untouched benchmarks
⏩ 46 skipped benchmarks¹

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_{Comparing wtcpython:sha256sum-dash-stdin (c26a1fb) with main (31bc9be)}

Footnotes

1. 46 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩