possible bug with python wrapper (shell=True)

[chrisewolf]

Hi guys, great tool!

Unfortunately it did not work "out of the box" (might be related to my python 2.7 on ubuntu), I had to add

shell=True

on line 36 in version.py

def get_latest_git_tag():
    tag = None
    get_tag_run = Popen(['git', 'describe', '--tags', '--dirty'],
                           stdout=PIPE, stderr=PIPE, shell=True)
    stdout, stderr = get_tag_run.communicate()
    if(not stderr.strip()):
        tag = stdout.strip()
    return tag

otherwise it would throw

Traceback (most recent call last):
  File "/home/chris/Downloads/bandup-master/bandup", line 71, in <module>
    parser = BandUpPythonArgumentParser()
  File "/home/chris/Downloads/bandup-master/src/python_interface/bandupy/argparse_wrapper.py", line 643, in __init__
    version='%(prog)s {version}'.format(version=__version__()))
  File "/home/chris/Downloads/bandup-master/src/python_interface/bandupy/version.py", line 43, in get_package_version
    pv = get_latest_git_tag()
  File "/home/chris/Downloads/bandup-master/src/python_interface/bandupy/version.py", line 36, in get_latest_git_tag
    stdout=PIPE, stderr=PIPE)
  File "/usr/lib/python2.7/subprocess.py", line 711, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1343, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

Best, Chris

[paulovcmedeiros]

Hi Chris!

Many thanks for your interest in BandUP and for reporting this issue. I've been able to reproduce it by running the code in an environment without git. I suspect this is the case in your system.

If subprocess tries to call a command that is not available, then an OSError exception is raised. Since all systems I use have git, I ended up overlooking this. I have now fixed the error by catching the exception. I prefer, however, not to use shell=True (see, for instance, https://docs.python.org/3.4/library/subprocess.html#security-considerations). This is avoided by catching the OSError exception.

Just FYI: The reason why shell=True works is because, by doing so, no exception is thrown. Instead, a "command not found" system error msg gets sent to the "stderr" variable and then "get_latest_git_tag" simply returns None. As discussed above, however, I prefer to avoid using shell=True if possible.

Many thanks once more for taking your time to report this issue. I appreciate and encourage this.

Best wishes, Paulo.