tar: support -f - for stdin/stdout archives

[kaladron]

When the archive path is "-", read archives from stdin for list and extract, and write archive data to stdout for create.

Route create status output to stderr when writing the archive to stdout so verbose output does not corrupt the stream. Add CLI tests for create-to-stdout, list-from-stdin, extract-from-stdin, and the stderr routing cases.

[codecov]

Codecov Report

❌ Patch coverage is 97.12230% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.78%. Comparing base (b4865da) to head (cef2373).
⚠️ Report is 13 commits behind head on main.

Files with missing lines	Patch %	Lines
tests/by-util/test_tar.rs	96.10%	3 Missing ⚠️
src/uu/tar/src/tar.rs	96.96%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #156      +/-   ##
==========================================
+ Coverage   96.59%   96.78%   +0.18%     
==========================================
  Files           9        9              
  Lines         941     1121     +180     
  Branches       24       28       +4     
==========================================
+ Hits          909     1085     +176     
- Misses         31       35       +4     
  Partials        1        1              

Flag	Coverage Δ
macos_latest	96.78% <97.12%> (+0.18%)	⬆️
ubuntu_latest	96.78% <97.12%> (+0.18%)	⬆️
windows_latest	0.00% <0.00%> (ø)

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[sylvestre]

GNU tar refuses -cf - when stdout is a tty (to avoid spewing binary). Maybe add aIsTerminal::is_terminal check and erroring out ?

[kaladron]

GNU tar refuses -cf - when stdout is a tty (to avoid spewing binary). Maybe add aIsTerminal::is_terminal check and erroring out ?

Fair point, I'll add that.

I'll need a few days to learn more about Rust's locking, though! =)

[sylvestre]

ping ? :)

[sylvestre]

needs to be rebased, sorry

[kaladron]

@sylvestre I was actually just trying to find the other PR I'd sent you - for this I was trying to figure out how the buffering ought to work. I haven't played a lot with efficient stdio in Rust yet. There are a bunch of other places where this could potentially apply.

And I swear I sent you a PR for those with a question and I'm not finding it.

[sylvestre]

no worries :)

[codspeed-hq]

Merging this PR will improve performance by 19.86%

⚡ 2 improved benchmarks
✅ 5 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	create_archive_100_files	504.9 µs	406.7 µs	+24.14%
⚡	create_archive_10_files	64.8 µs	56 µs	+15.73%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing kaladron:dashfdash (cef2373) with main (3eb916a)}

[kaladron]

Hi @sylvestre! Sorry about the delay. Your comments caused me to rework it a bit and I think I'm happy with the patch now. I appreciate any feedback you have.

[sylvestre]

well done!