On Wed, 15 Mar 2023 at 19:30, Jannik Glückert via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:

> This iteration improves error handling for copy_file_range,
> particularly around undocumented error codes in earlier kernel
> versions.
> Additionally this fixes the userspace copy fallback to handle
> zero-length files such as in
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108178.
>
> Lastly, the case "src gets resized during the copy loop" is now
> considered and will return true once the loop hits EOF (this is the
> only situation, aside from a zero-length src, where sendfile and
> copy_file_range return 0).
>

I've applied this patch (with some whitespace fixes) and started testing
it. I'm seeing some regressions:

FAIL: experimental/filesystem/operations/copy.cc execution test
FAIL: experimental/filesystem/operations/copy_file.cc execution test

The failures in the log look like:

terminate called after throwing an instance of
'std::experimental::filesystem::v1::__cxx11::filesystem_error'
 what():  filesystem error: cannot copy: Input/output error
[filesystem-test.copy.2900321341.ySWT77]
[filesystem-test.copy.2900321342.vjeAar]
FAIL: experimental/filesystem/operations/copy.cc execution test