fix(mv): don't panic if apply_xattrs fails

[alexs-sh]

About

This commit fixes #6727 by returning the error status instead of causing a panic. It aligns with the original GNU mv more closely

Before

cargo run -q mv dummy /run/media/user/8EC5-8BC8
thread 'main' panicked at src/uu/mv/src/mv.rs:682:47:
called `Result::unwrap()` on an `Err` value: Os { code: 95, kind: Uncategorized, message: "Operation not supported" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

After

cargo run -q mv dummy /run/media/user/8EC5-8BC8
mv: cannot move 'dummy' to '/run/media/user/8EC5-8BC8/dummy': Operation not supported

GNU mv

mv dummy /run/media/user/8EC5-8BC8
mv: preserving permissions for ‘/run/media/user/8EC5-8BC8/dummy’: Operation not supported

Testing environment

• ArchLinux
• rustc 1.83.0 (90b35a623 2024-11-26)
• Destination filesystem is FAT32

Commands for preparing a directory with xattrs

mkdir -p dummy/1
setfacl -m u:user:r dummy

Thank you

[sylvestre]

Could you please add a test to make sure we don't regress? Thanks

[alexs-sh]

@sylvestre Thx.

I thought about adding a test. However, it seems we have a problem here.

The most reliable way to reproduce the issue is by moving the directory to a filesystem that does not support xattrs. But this requires mounting the filesystem first, which requires root privileges. Running or requiring tests with root privileges seems like a very questionable approach.

dd if=/dev/zero of=fs bs=1M count=32
mkfs.vfat fs
mkdir dst
sudo mount fs dst #<--problem 

Possibly, I overlooked something. If you have any ideas, please let me know.

[sylvestre]

ok, it is good enough then :)
thanks