cp: better permissions mode handling with umask awareness

[my4ng]

Fix #9750, #10011, #10787, #10862, Supersede #10859.

This PR reworks the permissions mode handling such that its behaviour is in line with GNU's implementation. Specifically:

• set umask to !0o077, which means (1) cp can actually create and work with new directories/files which will have 700 permissions mode before their final calculated mode is set. the original umask is kept and passed around for calculation in the case of newly created and non-mode-preserving dir/files. umask is restored to original on exit.

• for explicit non-mode-preserving, newly created dir/files, use 777 and 666 modes for calculation respectively.

• for existing dir/files, leave existing mode unchanged except when preserving mode.

• for newly created dir/files, always set their permission mode to the correct one.

• added 12 new tests for the combination of existing/not-existing, no-preserve/default/preserve, dir/file one each for directory and file with rstest.

• improve performance by eliminating redundant heap allocations (e.g. PathBuf, String), ~25% from benchmark.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/cp/cp-parents. tests/cp/cp-parents is passing on 'main'. Maybe you have to rebase?
Skipping an intermittent issue tests/tty/tty-eof (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/factor/t34 is no longer failing!
Congrats! The gnu test tests/printf/printf-surprise is now passing!

[ChrisDryden]

Is there any way to split this PR up into something smaller? When its this big it gets pretty hard to review

[my4ng]

I'm afraid not. Most changes are actually from the noise of propagating orig_umask, and the only significant changes being build_dir and handle_mode. Without either, it results in a dozen or more failed tests.

There is a GNU test regression: tests/cp/cp-parents, caused by the second to last test in that file due to created parent dir not having attributes set correctly. Will fix soon.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/pr/bounded-memory. tests/pr/bounded-memory is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/tail/symlink (fails in this run but passes in the 'main' branch)
Congrats! The gnu test tests/factor/t34 is no longer failing!
Note: The gnu test tests/tail/pipe-f is now being skipped but was previously passing.
Congrats! The gnu test tests/printf/printf-surprise is now passing!

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/cut/bounded-memory. tests/cut/bounded-memory is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/misc/io-errors. tests/misc/io-errors is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/pr/bounded-memory. tests/pr/bounded-memory is passing on 'main'. Maybe you have to rebase?
Skipping an intermittent issue tests/tty/tty-eof (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/factor/t10 is no longer failing!

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/tail/tail-n0f is now passing!

[codspeed-hq]

Merging this PR will improve performance by 50.52%

⚡ 5 improved benchmarks
✅ 292 untouched benchmarks
⏩ 48 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	cp_archive_balanced_tree[(5, 4, 10)]	76.9 ms	62.1 ms	+23.79%
⚡	Simulation	cp_recursive_deep_tree[(120, 4)]	13.2 ms	8.8 ms	+50.52%
⚡	Simulation	cp_recursive_wide_tree[(6000, 800)]	187.7 ms	155.8 ms	+20.5%
⚡	Simulation	cp_preserve_metadata[(5, 4, 10)]	73.7 ms	59.1 ms	+24.73%
⚡	Simulation	cp_recursive_balanced_tree[(5, 4, 10)]	71.5 ms	56.6 ms	+26.4%

---

_{Comparing my4ng:cp_mode (63d08f3) with main (57f69ad)}

Footnotes

1. 48 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. ↩

[my4ng]

There are some residual problems with copy_file that I want to fix. In particular, currently it is setting the permissions (unnecessarily) twice, but the change appears to be more complex than I anticipated. Might split that into a separate PR just for clarity since this one is working and big enough already.

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/pr/bounded-memory (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/cut/bounded-memory is now being skipped but was previously passing.
Congrats! The gnu test tests/expand/bounded-memory is now passing!

[my4ng]

@ChrisDryden I have condensed the tests into two instead of the original 12, so it should be a lot more workable now.

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/misc/io-errors is no longer failing!