shutil.copytree() handles symbolic directory incorrectly

[shajunxing]

BPO	21697
Nosy	@ned-deily, @takluyver, @berkerpeksag
Files	截图 - 2014年06月09日 - 21时14分13秒.png: shutil.py source code screenshot issue21697.diff issue21697.diff shutil_copytree_symlink_dir.patch: Patch including test

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/berkerpeksag'
closed_at = <Date 2015-07-25.11:58:17.330>
created_at = <Date 2014-06-09.13:19:19.281>
labels = ['easy', 'type-bug', 'library']
title = 'shutil.copytree() handles symbolic directory incorrectly'
updated_at = <Date 2015-07-25.11:58:17.329>
user = 'https://bugs.python.org/shajunxing'

bugs.python.org fields:

activity = <Date 2015-07-25.11:58:17.329>
actor = 'berker.peksag'
assignee = 'berker.peksag'
closed = True
closed_date = <Date 2015-07-25.11:58:17.330>
closer = 'berker.peksag'
components = ['Library (Lib)']
creation = <Date 2014-06-09.13:19:19.281>
creator = 'shajunxing'
dependencies = []
files = ['35541', '35614', '35660', '39893']
hgrepos = []
issue_num = 21697
keywords = ['patch', 'easy']
message_count = 9.0
messages = ['220088', '220112', '220431', '220758', '224546', '232870', '246587', '247347', '247348']
nosy_count = 8.0
nosy_names = ['ned.deily', 'python-dev', 'takluyver', 'berker.peksag', 'puppet', 'Eduardo.Seabra', 'shajunxing', 'Bj\xc3\xb6rn.Dahlgren']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue21697'
versions = ['Python 3.4', 'Python 3.5', 'Python 3.6']

[shajunxing]

While using shutil.copytree() and the source containing symbolic directory (not symbolic file), an error will be raised. I checked the source code and found an obvlous mistake: shutil.copytree() using os.path.islink() to checker whether the source is a symbolic link, it's okay, but after doing this, os.path.isdir() should be called because a symbolic link may either be a file or a directry, shutil.copytree() just treated all of them as file, and invoke copy_function to copy it, so error happens.

I don't know whether newer versions have fixed this bug, but I googled it and found nothing.

[ned-deily]

Thanks for the report. The bug is still present in the 3.4 and default (what will become the 3.5 release) branches; the 3.3 branch now only accepts security fixes. 2.7 does not fail. Would you be interested in producing a patch for the problem?

[berkerpeksag]

Here's a patch. I'm getting the following error without modify Lib/shutil.py:

======================================================================
ERROR: test_copytree_symbolic_directory (test.test_shutil.TestShutil)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/home/berker/projects/cpython-default/Lib/test/test_shutil.py", line 650, in test_copytree_symbolic_directory
    shutil.copytree(src_dir, dst_dir)
  File "/home/berker/projects/cpython-default/Lib/shutil.py", line 342, in copytree
    raise Error(errors)
shutil.Error: [('/tmp/tmpiy30_34s/src/link', '/tmp/tmpiy30_34s/dst/link', "[Errno 21] Is a directory: '/tmp/tmpiy30_34s/src/link'")]

[EduardoSeabra]

Berker Peksag, I don't think your patch is okay.
When symlinks is set to true, it should copy the symbolic link of the directory. Your code is calling copytree instead.
I think the following patch is working, no errors on regression tests.

[puppet]

I have tested both patches on CentOS 6.4 and Eduardo Seabra:s patch works correctly with symlinks=True

[BjrnDahlgren]

I ran across this bug too. Applying Eduardo's patch got my package
working under Py 3.4

[takluyver]

Here's my patch (I submitted the duplicate issue). I think it's functionally the same as Eduardo's, but it also adds a test.

[python-dev]

New changeset e807f1d81cb6 by Berker Peksag in branch '3.4':
Issue bpo-21697: shutil.copytree() now correctly handles symbolic links that point to directories.
https://hg.python.org/cpython/rev/e807f1d81cb6

New changeset 31f4041b9286 by Berker Peksag in branch '3.5':
Issue bpo-21697: shutil.copytree() now correctly handles symbolic links that point to directories.
https://hg.python.org/cpython/rev/31f4041b9286

New changeset 8f65be73eb3a by Berker Peksag in branch 'default':
Issue bpo-21697: shutil.copytree() now correctly handles symbolic links that point to directories.
https://hg.python.org/cpython/rev/8f65be73eb3a

[berkerpeksag]

Thanks for the patches and testing!