[New-bugs-announce] [issue16957] shutil.which() shouldn't look in working directory on unix-y systems

Thomas Kluyver report at bugs.python.org
Sun Jan 13 23:13:51 CET 2013


New submission from Thomas Kluyver:

There's a 'short circuit' in shutil.which(), described as 'If we're given a full path which matches the mode and it exists, we're done here.'

It also matches if an executable file of the same name is present in the working directory, although on most Unix-y systems you need ./ to execute such files in a shell (i.e. ./foo, not just foo).

This could fool code calling which() into thinking that a program is installed, when it is not.

If we consider this a bug, one simple fix would be to only allow the short circuit with an absolute path, so the line

    if _access_check(cmd, mode):

would become

    if os.path.isabs(cmd) and _access_check(cmd, mode):

----------
components: Library (Lib)
messages: 179897
nosy: takluyver
priority: normal
severity: normal
status: open
title: shutil.which() shouldn't look in working directory on unix-y systems
type: behavior
versions: Python 3.3

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue16957>
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