[3.12] gh-109590: Update shutil.which on Windows to prefer a PATHEXT extension on executable files (GH-109995) (#110202)

gh-109590: Update shutil.which on Windows to prefer a PATHEXT extension on executable files (GH-109995)

The default arguments for shutil.which() request an executable file, but extensionless files are not executable on Windows and should be ignored.
(cherry picked from commit 29b875bb93)

Co-authored-by: Charles Machalow <csm10495@gmail.com>
This commit is contained in:
Miss Islington (bot) 2023-10-02 08:48:30 -07:00 committed by GitHub
parent 10af2242f4
commit b61a4da459
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4 changed files with 91 additions and 12 deletions

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@ -1554,8 +1554,16 @@ def which(cmd, mode=os.F_OK | os.X_OK, path=None):
if use_bytes:
pathext = [os.fsencode(ext) for ext in pathext]
# Always try checking the originally given cmd, if it doesn't match, try pathext
files = [cmd] + [cmd + ext for ext in pathext]
files = ([cmd] + [cmd + ext for ext in pathext])
# gh-109590. If we are looking for an executable, we need to look
# for a PATHEXT match. The first cmd is the direct match
# (e.g. python.exe instead of python)
# Check that direct match first if and only if the extension is in PATHEXT
# Otherwise check it last
suffix = os.path.splitext(files[0])[1].upper()
if mode & os.X_OK and not any(suffix == ext.upper() for ext in pathext):
files.append(files.pop(0))
else:
# On other platforms you don't have things like PATHEXT to tell you
# what file suffixes are executable, so just pass on cmd as-is.