bug#62607: cp --recursive --backup broken in 9.2

[Pádraig Brady]

On 01/04/2023 23:40, Kristian Klausen via GNU coreutils Bug Reports wrote:

Hi

After upgrading to coreutils 9.2-2 on Arch Linux the following:
mkdir -p src dst
touch {src,dst}/bar
cp --recursive --backup src/* dst
fails with:
cp: cannot create regular file 'dst/foo/bar': File exists

Running strace on cp I noticed:
renameat2(4, "foo/bar", 4, "foo/bar~", 0) = -1 ENOENT (No such file or
directory)

In coreutils 9.1-3 the syscall succeeds:
renameat2(4, "bar", 4, "bar~", 0)       = 0

I assume renameat2 is called with the wrong oldpath and newpath in 9.2
and that it should just be the basename and not the full relative path.

Cheers
Kristian Klausen

Your analysis is correct wrt the wrong paths being given to the renameat2().
This is related to https://bugs.gnu.org/55029

For completeness the correct repro is:

  mkdir -p {src,dst}/foo
  touch {src,dst}/foo/bar
  cp --recursive --backup src/* dst

thanks,
Pádraig