[issue26791] shutil.move fails to move symlink (Invalid cross-device link)
Jeffrey Kintscher
report at bugs.python.org
Thu Aug 6 03:10:23 EDT 2020
Jeffrey Kintscher <websurfer at surf2c.net> added the comment:
SilentGhost's analysis is correct. The provided example code causes the error because it is trying to move the symlink into its target when the target is a directory. Any cross-device moving issues are unrelated to this example code. Here is the relevant code in the master branch:
if os.path.isdir(dst):
if _samefile(src, dst):
# We might be on a case insensitive filesystem,
# perform the rename anyway.
os.rename(src, dst)
return
shutil._samefile() considers the example link and its target to be the same. When _samefile() returns False, this code gets executed:
real_dst = os.path.join(dst, _basename(src))
if os.path.exists(real_dst):
raise Error("Destination path '%s' already exists" % real_dst)
try:
os.rename(src, real_dst)
except OSError:
if os.path.islink(src):
linkto = os.readlink(src)
os.symlink(linkto, real_dst)
os.unlink(src)
A simple fix is to check whether src is a symlink when _samefile() returns True. The "Destination path...already exists" error isn't a problem for our symlink case because the shell mv command also returns an error.
$ ls -l /tmp/tmpdir/
total 0
lrwxr-xr-x 1 jeff staff 11 Aug 5 23:36 test_dir -> /tmp/tmpdir
$ mv test_dir /tmp/tmpdir
mv: test_dir and /tmp/tmpdir/test_dir are identical
I will generate a pull request.
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<https://bugs.python.org/issue26791>
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