[libcxx-commits] [libcxx] [libc++] Fix UB in filesystem::__copy for non-existent destination. (PR #87615)

[Afanasyev Ivan via libcxx-commits]

ivafanas wrote:

Hi!

I've searched for docs here:
https://linux.die.net/man/2/stat
https://man7.org/linux/man-pages/man2/stat.2.html

It does not state that `buf` parameter is not affected if error is returned. It is quite strange to update `buf` on failure, but, well, documentation allows it.

Problem is found on kernel 5.4.0 for the custom linux provided by our customer. Have no idea whether posix implementation of `stat` function is standard or customized.

https://github.com/llvm/llvm-project/pull/87615