[PATCH] PR libstdc++/83279 handle sendfile not copying entire file

[Jonathan Wakely <jwakely at redhat dot com>]

I failed to notice that the man page for sendfile(3) says it won't
copy more than 2GiB. This refactors the code to first try sendfile
(because it's fast if it works) and if that fails, or stops before the
end of the file, then use filebufs to copy what's left over.

I'm not adding a test because creating two files larger than 2G isn't
a good idea, but I've tested it locally.

	PR libstdc++/83279
	* src/filesystem/std-ops.cc (do_copy_file): Handle sendfile not
	copying entire file.

Tested x86_64-linux, committed to trunk. Backports to follow.

Attachment: patch.txt
Description: Text document