checksum: prepare further behavior fix with a rework

[RenjiSann]

Now that #6782, #6793 and #6815 have landed, it is time to achieve the rework of checksum.rs started in #6654.

This will allow us to fix #6572, #6614 and #6653.

This PR mainly tries to split the massive perform_checksum_verification in smaller functions, and to get rid of the &mut ChecksumResult that is passed everywhere, which makes it very difficult to understand where the global state of the program is modified.

Also, it adds ignored tests for future features (it will prevent too many conflicts when rebasing future PRs on each other).

Next PRs will focus on reworking the algorithm detection behavior, in particular for blake2b size guessing,
Regex detection behavior which for now prevents us from encountering both hexa and base64 digits in the same file.

[RenjiSann]

Depending on the feedback on this discussion, I might split the checksum.rs file into several files (a bit like the initial PR #6654).
I'd like to move Error structs to checksum/error.rs, everything that's Algorithm-related to checksum/algo.rs, etc...

What do you think ?

[cakebaker]

I'd like to move Error structs to checksum/error.rs, everything that's Algorithm-related to checksum/algo.rs, etc...

What do you think ?

It sounds good to me.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)

[RenjiSann]

I've finally decided to keep the splitting in several files for later, because it's a nightmare to mix changes and file architecture when you have to rebase to keep a sound change history.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)

[RenjiSann]

I'm not sure why the macos test failed. Is it just flakey or have I touched something ?

[sylvestre]

flaky:

---- test_stat::test_stdin_pipe_fifo1 stdout ----
run: /Users/runner/work/coreutils/coreutils/target/aarch64-apple-darwin/debug/coreutils stat -
run: /Users/runner/work/coreutils/coreutils/target/aarch64-apple-darwin/debug/coreutils stat -L -
thread 'test_stat::test_stdin_pipe_fifo1' panicked at ''  File: -
  Size: 0         	Blocks: 0          IO Block: 512    weird file
Device: 4ef1bb9ch/1324465052d	Inode: 500453238   Links: 0
Access: (0660/?rw-rw----)  Uid: (  501/  runner)   Gid: (   20/   staff)
Access: 2024-10-25 15:48:53.191317902 +0000
Modify: 2024-10-25 15:48:53.191317902 +0000
Change: 2024-10-25 15:48:53.191317902 +0000
 Birth: 1970-01-01 00:00:00.000000000 +0000
' does not contain 'fifo'', tests/by-util/test_stat.rs:288:10

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)

[RenjiSann]

@cakebaker Both of your comments address the details of implementation I came to when working on it.
If you come up with better alternatives, I'll gladly hear them ^^

[cakebaker]

Overall good job with this refactoring :)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/inotify-dir-recreate (fails in this run but passes in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/timeout/timeout (passes in this run but fails in the 'main' branch)

[RenjiSann]

Up @cakebaker
Once this is done, I will move on and fix the tests I added :)

[RenjiSann]

This PR might have been forgotten, just pinging maintainers for final review/merge @cakebaker @sylvestre ^^

[sylvestre]

thanks for the ping :)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/rm/rm1 (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)