From da6f098188c9825f10ae60db8987056b3a54c2e8 Mon Sep 17 00:00:00 2001 From: Christopher Marchfelder Date: Fri, 23 Oct 2020 12:08:24 +0200 Subject: [PATCH] bpo-40592: shutil.which will not return None anymore if ; is the last char in PATHEXT (GH-20088) shutil.which will not return None anymore for empty str in PATHEXT Empty PATHEXT will now be defaulted to _WIN_DEFAULT_PATHEXT --- Lib/shutil.py | 7 ++++++- Lib/test/test_shutil.py | 17 +++++++++++++++++ .../2020-05-14-16-01-34.bpo-40592.Cmk855.rst | 1 + 3 files changed, 24 insertions(+), 1 deletion(-) create mode 100644 Misc/NEWS.d/next/Library/2020-05-14-16-01-34.bpo-40592.Cmk855.rst diff --git a/Lib/shutil.py b/Lib/shutil.py index a4ce2c0290b..223e9a8a705 100644 --- a/Lib/shutil.py +++ b/Lib/shutil.py @@ -53,6 +53,9 @@ COPY_BUFSIZE = 1024 * 1024 if _WINDOWS else 64 * 1024 _USE_CP_SENDFILE = hasattr(os, "sendfile") and sys.platform.startswith("linux") _HAS_FCOPYFILE = posix and hasattr(posix, "_fcopyfile") # macOS +# CMD defaults in Windows 10 +_WIN_DEFAULT_PATHEXT = ".COM;.EXE;.BAT;.CMD;.VBS;.JS;.WS;.MSC" + __all__ = ["copyfileobj", "copyfile", "copymode", "copystat", "copy", "copy2", "copytree", "move", "rmtree", "Error", "SpecialFileError", "ExecError", "make_archive", "get_archive_formats", @@ -1415,7 +1418,9 @@ def which(cmd, mode=os.F_OK | os.X_OK, path=None): path.insert(0, curdir) # PATHEXT is necessary to check on Windows. - pathext = os.environ.get("PATHEXT", "").split(os.pathsep) + pathext_source = os.getenv("PATHEXT") or _WIN_DEFAULT_PATHEXT + pathext = [ext for ext in pathext_source.split(os.pathsep) if ext] + if use_bytes: pathext = [os.fsencode(ext) for ext in pathext] # See if the given file matches any of the expected path extensions. diff --git a/Lib/test/test_shutil.py b/Lib/test/test_shutil.py index 06ca50af143..890f2c7d406 100644 --- a/Lib/test/test_shutil.py +++ b/Lib/test/test_shutil.py @@ -1849,6 +1849,23 @@ class TestWhich(BaseTest, unittest.TestCase): rv = shutil.which(program, path=self.temp_dir) self.assertEqual(rv, temp_filexyz.name) + # Issue 40592: See https://bugs.python.org/issue40592 + @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows') + def test_pathext_with_empty_str(self): + ext = ".xyz" + temp_filexyz = tempfile.NamedTemporaryFile(dir=self.temp_dir, + prefix="Tmp2", suffix=ext) + self.addCleanup(temp_filexyz.close) + + # strip path and extension + program = os.path.basename(temp_filexyz.name) + program = os.path.splitext(program)[0] + + with os_helper.EnvironmentVarGuard() as env: + env['PATHEXT'] = f"{ext};" # note the ; + rv = shutil.which(program, path=self.temp_dir) + self.assertEqual(rv, temp_filexyz.name) + class TestWhichBytes(TestWhich): def setUp(self): diff --git a/Misc/NEWS.d/next/Library/2020-05-14-16-01-34.bpo-40592.Cmk855.rst b/Misc/NEWS.d/next/Library/2020-05-14-16-01-34.bpo-40592.Cmk855.rst new file mode 100644 index 00000000000..3211a1bc345 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-05-14-16-01-34.bpo-40592.Cmk855.rst @@ -0,0 +1 @@ +:func:`shutil.which` now ignores empty entries in :envvar:`PATHEXT` instead of treating them as a match.