bpo-33721: Make some os.path functions and pathlib.Path methods be tolerant to invalid paths. (#7695)

Such functions as os.path.exists(), os.path.lexists(), os.path.isdir(),
os.path.isfile(), os.path.islink(), and os.path.ismount() now return False
instead of raising ValueError or its subclasses UnicodeEncodeError
and UnicodeDecodeError for paths that contain characters or bytes
unrepresentative at the OS level.

9 files changed, 110 insertions, 27 deletions

diff --git a/Lib/genericpath.py b/Lib/genericpath.py
index 303b3b3..5dd703d 100644
--- a/Lib/genericpath.py
+++ b/Lib/genericpath.py
@@ -17,7 +17,7 @@ def exists(path):
     """Test whether a path exists.  Returns False for broken symbolic links"""
     try:
         os.stat(path)
-    except OSError:
+    except (OSError, ValueError):
         return False
     return True
 
@@ -28,7 +28,7 @@ def isfile(path):
     """Test whether a path is a regular file"""
     try:
         st = os.stat(path)
-    except OSError:
+    except (OSError, ValueError):
         return False
     return stat.S_ISREG(st.st_mode)
 
@@ -40,7 +40,7 @@ def isdir(s):
     """Return true if the pathname refers to an existing directory."""
     try:
         st = os.stat(s)
-    except OSError:
+    except (OSError, ValueError):
         return False
     return stat.S_ISDIR(st.st_mode)
 
diff --git a/Lib/macpath.py b/Lib/macpath.py
index aacf723..9a12d2f 100644
--- a/Lib/macpath.py
+++ b/Lib/macpath.py
@@ -138,7 +138,7 @@ def lexists(path):
 
     try:
         st = os.lstat(path)
-    except OSError:
+    except (OSError, ValueError):
         return False
     return True
 
diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index f0e03a2..0e6de28 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -229,7 +229,7 @@ def islink(path):
     """
     try:
         st = os.lstat(path)
-    except (OSError, AttributeError):
+    except (OSError, ValueError, AttributeError):
         return False
     return stat.S_ISLNK(st.st_mode)
 
@@ -239,7 +239,7 @@ def lexists(path):
     """Test whether a path exists.  Returns True for broken symbolic links"""
     try:
         st = os.lstat(path)
-    except OSError:
+    except (OSError, ValueError):
         return False
     return True
 
@@ -524,7 +524,7 @@ else:  # use native Windows method on Windows
         """Return the absolute version of a path."""
         try:
             return _getfullpathname(path)
-        except OSError:
+        except (OSError, ValueError):
             return _abspath_fallback(path)
 
 # realpath is a no-op on systems without islink support
diff --git a/Lib/pathlib.py b/Lib/pathlib.py
index c2986bd..89dffa5 100644
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -1331,6 +1331,9 @@ class Path(PurePath):
             if e.errno not in _IGNORED_ERROS:
                 raise
             return False
+        except ValueError:
+            # Non-encodable path
+            return False
         return True
 
     def is_dir(self):
@@ -1345,6 +1348,9 @@ class Path(PurePath):
             # Path doesn't exist or is a broken symlink
             # (see https://bitbucket.org/pitrou/pathlib/issue/12/)
             return False
+        except ValueError:
+            # Non-encodable path
+            return False
 
     def is_file(self):
         """
@@ -1359,6 +1365,9 @@ class Path(PurePath):
             # Path doesn't exist or is a broken symlink
             # (see https://bitbucket.org/pitrou/pathlib/issue/12/)
             return False
+        except ValueError:
+            # Non-encodable path
+            return False
 
     def is_mount(self):
         """
@@ -1392,6 +1401,9 @@ class Path(PurePath):
                 raise
             # Path doesn't exist
             return False
+        except ValueError:
+            # Non-encodable path
+            return False
 
     def is_block_device(self):
         """
@@ -1405,6 +1417,9 @@ class Path(PurePath):
             # Path doesn't exist or is a broken symlink
             # (see https://bitbucket.org/pitrou/pathlib/issue/12/)
             return False
+        except ValueError:
+            # Non-encodable path
+            return False
 
     def is_char_device(self):
         """
@@ -1418,6 +1433,9 @@ class Path(PurePath):
             # Path doesn't exist or is a broken symlink
             # (see https://bitbucket.org/pitrou/pathlib/issue/12/)
             return False
+        except ValueError:
+            # Non-encodable path
+            return False
 
     def is_fifo(self):
         """
@@ -1431,6 +1449,9 @@ class Path(PurePath):
             # Path doesn't exist or is a broken symlink
             # (see https://bitbucket.org/pitrou/pathlib/issue/12/)
             return False
+        except ValueError:
+            # Non-encodable path
+            return False
 
     def is_socket(self):
         """
@@ -1444,6 +1465,9 @@ class Path(PurePath):
             # Path doesn't exist or is a broken symlink
             # (see https://bitbucket.org/pitrou/pathlib/issue/12/)
             return False
+        except ValueError:
+            # Non-encodable path
+            return False
 
     def expanduser(self):
         """ Return a new path with expanded ~ and ~user constructs
diff --git a/Lib/posixpath.py b/Lib/posixpath.py
index e92186c..7e3f3db 100644
--- a/Lib/posixpath.py
+++ b/Lib/posixpath.py
@@ -169,7 +169,7 @@ def islink(path):
     """Test whether a path is a symbolic link"""
     try:
         st = os.lstat(path)
-    except (OSError, AttributeError):
+    except (OSError, ValueError, AttributeError):
         return False
     return stat.S_ISLNK(st.st_mode)
 
@@ -179,7 +179,7 @@ def lexists(path):
     """Test whether a path exists.  Returns True for broken symbolic links"""
     try:
         os.lstat(path)
-    except OSError:
+    except (OSError, ValueError):
         return False
     return True
 
@@ -191,7 +191,7 @@ def ismount(path):
     """Test whether a path is a mount point"""
     try:
         s1 = os.lstat(path)
-    except OSError:
+    except (OSError, ValueError):
         # It doesn't exist -- so not a mount point. :-)
         return False
     else:
@@ -206,7 +206,7 @@ def ismount(path):
     parent = realpath(parent)
     try:
         s2 = os.lstat(parent)
-    except OSError:
+    except (OSError, ValueError):
         return False
 
     dev1 = s1.st_dev
diff --git a/Lib/test/test_genericpath.py b/Lib/test/test_genericpath.py
index 8b291cd..08e1c12 100644
--- a/Lib/test/test_genericpath.py
+++ b/Lib/test/test_genericpath.py
@@ -138,10 +138,20 @@ class GenericTest:
         self.assertIs(self.pathmodule.exists(filename), True)
         self.assertIs(self.pathmodule.exists(bfilename), True)
 
+        self.assertIs(self.pathmodule.exists(filename + '\udfff'), False)
+        self.assertIs(self.pathmodule.exists(bfilename + b'\xff'), False)
+        self.assertIs(self.pathmodule.exists(filename + '\x00'), False)
+        self.assertIs(self.pathmodule.exists(bfilename + b'\x00'), False)
+
         if self.pathmodule is not genericpath:
             self.assertIs(self.pathmodule.lexists(filename), True)
             self.assertIs(self.pathmodule.lexists(bfilename), True)
 
+            self.assertIs(self.pathmodule.lexists(filename + '\udfff'), False)
+            self.assertIs(self.pathmodule.lexists(bfilename + b'\xff'), False)
+            self.assertIs(self.pathmodule.lexists(filename + '\x00'), False)
+            self.assertIs(self.pathmodule.lexists(bfilename + b'\x00'), False)
+
     @unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
     def test_exists_fd(self):
         r, w = os.pipe()
@@ -158,6 +168,11 @@ class GenericTest:
         self.assertIs(self.pathmodule.isdir(filename), False)
         self.assertIs(self.pathmodule.isdir(bfilename), False)
 
+        self.assertIs(self.pathmodule.isdir(filename + '\udfff'), False)
+        self.assertIs(self.pathmodule.isdir(bfilename + b'\xff'), False)
+        self.assertIs(self.pathmodule.isdir(filename + '\x00'), False)
+        self.assertIs(self.pathmodule.isdir(bfilename + b'\x00'), False)
+
         try:
             create_file(filename)
             self.assertIs(self.pathmodule.isdir(filename), False)
@@ -178,6 +193,11 @@ class GenericTest:
         self.assertIs(self.pathmodule.isfile(filename), False)
         self.assertIs(self.pathmodule.isfile(bfilename), False)
 
+        self.assertIs(self.pathmodule.isfile(filename + '\udfff'), False)
+        self.assertIs(self.pathmodule.isfile(bfilename + b'\xff'), False)
+        self.assertIs(self.pathmodule.isfile(filename + '\x00'), False)
+        self.assertIs(self.pathmodule.isfile(bfilename + b'\x00'), False)
+
         try:
             create_file(filename)
             self.assertIs(self.pathmodule.isfile(filename), True)
@@ -298,18 +318,20 @@ class TestGenericTest(GenericTest, unittest.TestCase):
                 continue
             func = getattr(self.pathmodule, attr)
             with self.subTest(attr=attr):
-                try:
+                if attr in ('exists', 'isdir', 'isfile'):
                     func('/tmp\udfffabcds')
-                except (OSError, UnicodeEncodeError):
-                    pass
-                try:
                     func(b'/tmp\xffabcds')
-                except (OSError, UnicodeDecodeError):
-                    pass
-                with self.assertRaisesRegex(ValueError, 'embedded null'):
                     func('/tmp\x00abcds')
-                with self.assertRaisesRegex(ValueError, 'embedded null'):
                     func(b'/tmp\x00abcds')
+                else:
+                    with self.assertRaises((OSError, UnicodeEncodeError)):
+                        func('/tmp\udfffabcds')
+                    with self.assertRaises((OSError, UnicodeDecodeError)):
+                        func(b'/tmp\xffabcds')
+                    with self.assertRaisesRegex(ValueError, 'embedded null'):
+                        func('/tmp\x00abcds')
+                    with self.assertRaisesRegex(ValueError, 'embedded null'):
+                        func(b'/tmp\x00abcds')
 
 # Following TestCase is not supposed to be run from test_genericpath.
 # It is inherited by other test modules (macpath, ntpath, posixpath).
diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
index e436db9..876eecc 100644
--- a/Lib/test/test_pathlib.py
+++ b/Lib/test/test_pathlib.py
@@ -1342,6 +1342,8 @@ class _BasePathTest(object):
             self.assertIs(False, (p / 'linkA' / 'bah').exists())
         self.assertIs(False, (p / 'foo').exists())
         self.assertIs(False, P('/xyzzy').exists())
+        self.assertIs(False, P(BASE + '\udfff').exists())
+        self.assertIs(False, P(BASE + '\x00').exists())
 
     def test_open_common(self):
         p = self.cls(BASE)
@@ -1866,7 +1868,9 @@ class _BasePathTest(object):
         if support.can_symlink():
             self.assertFalse((P / 'linkA').is_dir())
             self.assertTrue((P / 'linkB').is_dir())
-            self.assertFalse((P/ 'brokenLink').is_dir())
+            self.assertFalse((P/ 'brokenLink').is_dir(), False)
+        self.assertIs((P / 'dirA\udfff').is_dir(), False)
+        self.assertIs((P / 'dirA\x00').is_dir(), False)
 
     def test_is_file(self):
         P = self.cls(BASE)
@@ -1878,6 +1882,8 @@ class _BasePathTest(object):
             self.assertTrue((P / 'linkA').is_file())
             self.assertFalse((P / 'linkB').is_file())
             self.assertFalse((P/ 'brokenLink').is_file())
+        self.assertIs((P / 'fileA\udfff').is_file(), False)
+        self.assertIs((P / 'fileA\x00').is_file(), False)
 
     @only_posix
     def test_is_mount(self):
@@ -1890,6 +1896,8 @@ class _BasePathTest(object):
         self.assertTrue(R.is_mount())
         if support.can_symlink():
             self.assertFalse((P / 'linkA').is_mount())
+        self.assertIs(self.cls('/\udfff').is_mount(), False)
+        self.assertIs(self.cls('/\x00').is_mount(), False)
 
     def test_is_symlink(self):
         P = self.cls(BASE)
@@ -1901,6 +1909,11 @@ class _BasePathTest(object):
             self.assertTrue((P / 'linkA').is_symlink())
             self.assertTrue((P / 'linkB').is_symlink())
             self.assertTrue((P/ 'brokenLink').is_symlink())
+        self.assertIs((P / 'fileA\udfff').is_file(), False)
+        self.assertIs((P / 'fileA\x00').is_file(), False)
+        if support.can_symlink():
+            self.assertIs((P / 'linkA\udfff').is_file(), False)
+            self.assertIs((P / 'linkA\x00').is_file(), False)
 
     def test_is_fifo_false(self):
         P = self.cls(BASE)
@@ -1908,6 +1921,8 @@ class _BasePathTest(object):
         self.assertFalse((P / 'dirA').is_fifo())
         self.assertFalse((P / 'non-existing').is_fifo())
         self.assertFalse((P / 'fileA' / 'bah').is_fifo())
+        self.assertIs((P / 'fileA\udfff').is_fifo(), False)
+        self.assertIs((P / 'fileA\x00').is_fifo(), False)
 
     @unittest.skipUnless(hasattr(os, "mkfifo"), "os.mkfifo() required")
     def test_is_fifo_true(self):
@@ -1919,6 +1934,8 @@ class _BasePathTest(object):
         self.assertTrue(P.is_fifo())
         self.assertFalse(P.is_socket())
         self.assertFalse(P.is_file())
+        self.assertIs(self.cls(BASE, 'myfifo\udfff').is_fifo(), False)
+        self.assertIs(self.cls(BASE, 'myfifo\x00').is_fifo(), False)
 
     def test_is_socket_false(self):
         P = self.cls(BASE)
@@ -1926,6 +1943,8 @@ class _BasePathTest(object):
         self.assertFalse((P / 'dirA').is_socket())
         self.assertFalse((P / 'non-existing').is_socket())
         self.assertFalse((P / 'fileA' / 'bah').is_socket())
+        self.assertIs((P / 'fileA\udfff').is_socket(), False)
+        self.assertIs((P / 'fileA\x00').is_socket(), False)
 
     @unittest.skipUnless(hasattr(socket, "AF_UNIX"), "Unix sockets required")
     def test_is_socket_true(self):
@@ -1941,6 +1960,8 @@ class _BasePathTest(object):
         self.assertTrue(P.is_socket())
         self.assertFalse(P.is_fifo())
         self.assertFalse(P.is_file())
+        self.assertIs(self.cls(BASE, 'mysock\udfff').is_socket(), False)
+        self.assertIs(self.cls(BASE, 'mysock\x00').is_socket(), False)
 
     def test_is_block_device_false(self):
         P = self.cls(BASE)
@@ -1948,6 +1969,8 @@ class _BasePathTest(object):
         self.assertFalse((P / 'dirA').is_block_device())
         self.assertFalse((P / 'non-existing').is_block_device())
         self.assertFalse((P / 'fileA' / 'bah').is_block_device())
+        self.assertIs((P / 'fileA\udfff').is_block_device(), False)
+        self.assertIs((P / 'fileA\x00').is_block_device(), False)
 
     def test_is_char_device_false(self):
         P = self.cls(BASE)
@@ -1955,6 +1978,8 @@ class _BasePathTest(object):
         self.assertFalse((P / 'dirA').is_char_device())
         self.assertFalse((P / 'non-existing').is_char_device())
         self.assertFalse((P / 'fileA' / 'bah').is_char_device())
+        self.assertIs((P / 'fileA\udfff').is_char_device(), False)
+        self.assertIs((P / 'fileA\x00').is_char_device(), False)
 
     def test_is_char_device_true(self):
         # Under Unix, /dev/null should generally be a char device
@@ -1964,6 +1989,8 @@ class _BasePathTest(object):
         self.assertTrue(P.is_char_device())
         self.assertFalse(P.is_block_device())
         self.assertFalse(P.is_file())
+        self.assertIs(self.cls('/dev/null\udfff').is_char_device(), False)
+        self.assertIs(self.cls('/dev/null\x00').is_char_device(), False)
 
     def test_pickling_common(self):
         p = self.cls(BASE, 'fileA')
diff --git a/Lib/test/test_posixpath.py b/Lib/test/test_posixpath.py
index 9476ede..ae59ef5 100644
--- a/Lib/test/test_posixpath.py
+++ b/Lib/test/test_posixpath.py
@@ -153,9 +153,11 @@ class PosixPathTest(unittest.TestCase):
     def test_islink(self):
         self.assertIs(posixpath.islink(support.TESTFN + "1"), False)
         self.assertIs(posixpath.lexists(support.TESTFN + "2"), False)
+
         with open(support.TESTFN + "1", "wb") as f:
             f.write(b"foo")
         self.assertIs(posixpath.islink(support.TESTFN + "1"), False)
+
         if support.can_symlink():
             os.symlink(support.TESTFN + "1", support.TESTFN + "2")
             self.assertIs(posixpath.islink(support.TESTFN + "2"), True)
@@ -164,6 +166,11 @@ class PosixPathTest(unittest.TestCase):
             self.assertIs(posixpath.exists(support.TESTFN + "2"), False)
             self.assertIs(posixpath.lexists(support.TESTFN + "2"), True)
 
+        self.assertIs(posixpath.islink(support.TESTFN + "\udfff"), False)
+        self.assertIs(posixpath.islink(os.fsencode(support.TESTFN) + b"\xff"), False)
+        self.assertIs(posixpath.islink(support.TESTFN + "\x00"), False)
+        self.assertIs(posixpath.islink(os.fsencode(support.TESTFN) + b"\x00"), False)
+
     def test_ismount(self):
         self.assertIs(posixpath.ismount("/"), True)
         self.assertIs(posixpath.ismount(b"/"), True)
@@ -177,6 +184,11 @@ class PosixPathTest(unittest.TestCase):
         finally:
             safe_rmdir(ABSTFN)
 
+        self.assertIs(posixpath.ismount('/\udfff'), False)
+        self.assertIs(posixpath.ismount(b'/\xff'), False)
+        self.assertIs(posixpath.ismount('/\x00'), False)
+        self.assertIs(posixpath.ismount(b'/\x00'), False)
+
     @unittest.skipUnless(support.can_symlink(),
                          "Test requires symlink support")
     def test_ismount_symlinks(self):
diff --git a/Lib/test/test_site.py b/Lib/test/test_site.py
index e3c9dee..742be1e 100644
--- a/Lib/test/test_site.py
+++ b/Lib/test/test_site.py
@@ -159,13 +159,11 @@ class HelperFunctionsTests(unittest.TestCase):
         # Issue 5258
         pth_dir, pth_fn = self.make_pth("abc\x00def\n")
         with captured_stderr() as err_out:
-            site.addpackage(pth_dir, pth_fn, set())
-        self.assertRegex(err_out.getvalue(), "line 1")
-        self.assertRegex(err_out.getvalue(),
-            re.escape(os.path.join(pth_dir, pth_fn)))
-        # XXX: ditto previous XXX comment.
-        self.assertRegex(err_out.getvalue(), 'Traceback')
-        self.assertRegex(err_out.getvalue(), 'ValueError')
+            self.assertFalse(site.addpackage(pth_dir, pth_fn, set()))
+        self.assertEqual(err_out.getvalue(), "")
+        for path in sys.path:
+            if isinstance(path, str):
+                self.assertNotIn("abc\x00def", path)
 
     def test_addsitedir(self):
         # Same tests for test_addpackage since addsitedir() essentially just