Raising of GitCommandError fails in archive function if stdout was a cStringIO object

[wohauser]

I tried to check out an archive for a not existing path from the repository and I expect a GitCommandError exception.

I got following TypeError exception:
"Expected bytes or text, but got <cStringIO.StringO object at 0x7fabac6f97a0>"

I did following:
fpt = StringIO()
-- (used as a temporary storage for the tar archive)
self._repository.archive(fpt, treeish=version_identifier, format="tar", path=sub_path)
-- (where sub_path points to an not existing path)

The cause of the problem was, the Constructor of the GitCommandError could not handle the cStringIO object. (a normal file pointer may be faulty too).
I suppose it should set its stdout variable to None in case of not handled types. Or it should be adjusted when raising the exception.

[Byron]

Using the latest version of GitPython (39335e6) on OSX on python 2.7, I was unable to reproduce the issue.

Please feel free to provide more information to help reproducing it - maybe this functionality is platform dependent. In the meanwhile, I am closing this issue.

[wohauser]

Try it with a path filter using a path that not exists in the repo.

e.g.

r.archive(fpt,format="tar",path="tttt")

results in 
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/git/repo/base.py", line 969, in archive
    self.git.archive(treeish, *path, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/git/cmd.py", line 425, in <lambda>
    return lambda *args, **kwargs: self._call_process(name, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/git/cmd.py", line 877, in _call_process
    return self.execute(call, **exec_kwargs)
  File "/usr/local/lib/python2.7/dist-packages/git/cmd.py", line 688, in execute
    raise GitCommandError(command, status, stderr_value, stdout_value)
  File "/usr/local/lib/python2.7/dist-packages/git/exc.py", line 74, in __init__
    super(GitCommandError, self).__init__(command, status, stderr, stdout)
  File "/usr/local/lib/python2.7/dist-packages/git/exc.py", line 54, in __init__
    self.stdout = stdout and u"\n  stdout: '%s'" % safe_decode(stdout) or ''
  File "/usr/local/lib/python2.7/dist-packages/git/compat.py", line 74, in safe_decode
    raise TypeError('Expected bytes or text, but got %r' % (s,))
TypeError: Expected bytes or text, but got <cStringIO.StringO object at 0x7f17a2ec36c0>

Using:
Name: GitPython
Version: 2.1.3

python 2.7

On Ubuntu 16.04.2 LTS

[wohauser]

The error is the same using the version you tested (39335e6)

[wohauser]

Ping

[Byron]

I tried to reproduce it again, and in python2.6 I get other errors than in python 3. In any case it does not work at least when done interactively. There are a few tests which obviously don't fail, but they don't try it on a path filter that yields no files.
It should be relatively straightforward to reproduce the issue in case you are interested.

[the-owl]

I'm having a similar issue. It seems that this bug is generic and affects all git commands: calling any git command that returns error while output_stream is set leads to this TypeError. Simple example (run this in any git repo, python 2.7):

import git
import tempfile

repo = git.Repo.init('.')
tf = tempfile.TemporaryFile()
repo.git.checkout('non-existent-branch', output_stream=tf)

On my machine (Python 2.7.14, Linux, GitPython 2.1.10) this script produces the following output:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/site-packages/git/cmd.py", line 548, in <lambda>
    return lambda *args, **kwargs: self._call_process(name, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/git/cmd.py", line 1014, in _call_process
    return self.execute(call, **exec_kwargs)
  File "/usr/lib/python2.7/site-packages/git/cmd.py", line 825, in execute
    raise GitCommandError(command, status, stderr_value, stdout_value)
  File "/usr/lib/python2.7/site-packages/git/exc.py", line 78, in __init__
    super(GitCommandError, self).__init__(command, status, stderr, stdout)
  File "/usr/lib/python2.7/site-packages/git/exc.py", line 58, in __init__
    self.stdout = stdout and u"\n  stdout: '%s'" % safe_decode(stdout) or ''
  File "/usr/lib/python2.7/site-packages/git/compat.py", line 74, in safe_decode
    raise TypeError('Expected bytes or text, but got %r' % (s,))
TypeError: Expected bytes or text, but got <open file '<fdopen>', mode 'w+b' at 0x7fc0914d1300>

https://github.com/gitpython-developers/GitPython/blob/master/git/cmd.py#L797
This line looks suspicious: while stderr_value is set to result of proc.stderr.read(), stdout_value is set to output_stream object.

[Byron]

@the-owl Thanks for your input! It looks like your code-example is perfect for a small unit-test due it it being perfectly isolated. The parameter docs clearly state that a file-like object is expected, and the example above should work.
Maybe a fix is rather straightforward, would you want to have a go at it?

[the-owl]

@Byron Yes, the fix is really straightforward - just a single line in cmd.py. I've sent a PR that fixes the issue, along with a test that fails without the fix: #782