Clean up code which checked presence of os.{stat,lstat,chmod} (#11643)

Lib/dbm/dumb.py

@@ -278,8 +278,7 @@ class _Database(collections.abc.MutableMapping):
     __del__ = close
 
     def _chmod(self, file):
-        if hasattr(self._os, 'chmod'):
+        self._os.chmod(file, self._mode)
-            self._os.chmod(file, self._mode)
 
     def __enter__(self):
         return self

Lib/fileinput.py

@@ -357,8 +357,7 @@ class FileInput:
                     fd = os.open(self._filename, mode, perm)
                     self._output = os.fdopen(fd, "w")
                     try:
-                        if hasattr(os, 'chmod'):
+                        os.chmod(self._filename, perm)
-                            os.chmod(self._filename, perm)
                     except OSError:
                         pass
                 self._savestdout = sys.stdout

Lib/shutil.py

@@ -290,10 +290,8 @@ def copymode(src, dst, *, follow_symlinks=True):
             stat_func, chmod_func = os.lstat, os.lchmod
         else:
             return
-    elif hasattr(os, 'chmod'):
-        stat_func, chmod_func = _stat, os.chmod
     else:
-        return
+        stat_func, chmod_func = _stat, os.chmod
 
     st = stat_func(src)
     chmod_func(dst, stat.S_IMODE(st.st_mode))

Lib/tarfile.py

@@ -1787,10 +1787,9 @@ class TarFile(object):
         tarinfo = self.tarinfo()
         tarinfo.tarfile = self  # Not needed
 
-        # Use os.stat or os.lstat, depending on platform
+        # Use os.stat or os.lstat, depending on if symlinks shall be resolved.
-        # and if symlinks shall be resolved.
         if fileobj is None:
-            if hasattr(os, "lstat") and not self.dereference:
+            if not self.dereference:
                 statres = os.lstat(name)
             else:
                 statres = os.stat(name)
@@ -2235,11 +2234,10 @@ class TarFile(object):
     def chmod(self, tarinfo, targetpath):
         """Set file permissions of targetpath according to tarinfo.
         """
-        if hasattr(os, 'chmod'):
+        try:
-            try:
+            os.chmod(targetpath, tarinfo.mode)
-                os.chmod(targetpath, tarinfo.mode)
+        except OSError:
-            except OSError:
+            raise ExtractError("could not change mode")
-                raise ExtractError("could not change mode")
 
     def utime(self, tarinfo, targetpath):
         """Set modification time of targetpath according to tarinfo.

Lib/tempfile.py

@@ -70,20 +70,10 @@ template = "tmp"
 
 _once_lock = _allocate_lock()
 
-if hasattr(_os, "lstat"):
-    _stat = _os.lstat
-elif hasattr(_os, "stat"):
-    _stat = _os.stat
-else:
-    # Fallback.  All we need is something that raises OSError if the
-    # file doesn't exist.
-    def _stat(fn):
-        fd = _os.open(fn, _os.O_RDONLY)
-        _os.close(fd)
 
 def _exists(fn):
     try:
-        _stat(fn)
+        _os.lstat(fn)
     except OSError:
         return False
     else:

Lib/test/libregrtest/runtest.py

@@ -249,10 +249,8 @@ def cleanup_test_droppings(testname, verbose):
         if verbose:
             print("%r left behind %s %r" % (testname, kind, name))
         try:
-            # if we have chmod, fix possible permissions problems
+            # fix possible permissions problems that might prevent cleanup
-            # that might prevent cleanup
+            os.chmod(name, stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO)
-            if (hasattr(os, 'chmod')):
-                os.chmod(name, stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO)
             nuker(name)
         except Exception as msg:
             print(("%r left behind %s %r and it couldn't be "

Lib/test/pickletester.py

@@ -1568,11 +1568,10 @@ class AbstractPickleTests(unittest.TestCase):
             s = self.dumps(t, proto)
             u = self.loads(s)
             self.assert_is_copy(t, u)
-            if hasattr(os, "stat"):
+            t = os.stat(os.curdir)
-                t = os.stat(os.curdir)
+            s = self.dumps(t, proto)
-                s = self.dumps(t, proto)
+            u = self.loads(s)
-                u = self.loads(s)
+            self.assert_is_copy(t, u)
-                self.assert_is_copy(t, u)
             if hasattr(os, "statvfs"):
                 t = os.statvfs(os.curdir)
                 s = self.dumps(t, proto)

Lib/test/test_compileall.py

@@ -57,7 +57,6 @@ class CompileallTestsBase:
         compare = struct.pack('<4sll', importlib.util.MAGIC_NUMBER, 0, mtime)
         return data, compare
 
-    @unittest.skipUnless(hasattr(os, 'stat'), 'test needs os.stat()')
     def recreation_check(self, metadata):
         """Check that compileall recreates bytecode when the new metadata is
         used."""

Lib/test/test_dbm_dumb.py

@@ -40,7 +40,6 @@ class DumbDBMTestCase(unittest.TestCase):
         f.close()
 
     @unittest.skipUnless(hasattr(os, 'umask'), 'test needs os.umask()')
-    @unittest.skipUnless(hasattr(os, 'chmod'), 'test needs os.chmod()')
     def test_dumbdbm_creation_mode(self):
         try:
             old_umask = os.umask(0o002)
@@ -275,7 +274,6 @@ class DumbDBMTestCase(unittest.TestCase):
                                         "'r', 'w', 'c', or 'n'"):
                 dumbdbm.open(_fname, flag)
 
-    @unittest.skipUnless(hasattr(os, 'chmod'), 'test needs os.chmod()')
     def test_readonly_files(self):
         with support.temp_dir() as dir:
             fname = os.path.join(dir, 'db')

Lib/test/test_fileinput.py

@@ -428,7 +428,6 @@ class FileInputTests(BaseTests, unittest.TestCase):
         self.assertTrue(os_fstat_replacement.invoked,
                         "os.fstat() was not invoked")
 
-    @unittest.skipIf(not hasattr(os, "chmod"), "os.chmod does not exist")
     def test_readline_os_chmod_raises_OSError(self):
         """Tests invoking FileInput.readline() when os.chmod() raises OSError.
            This exception should be silently discarded."""

Lib/test/test_mailbox.py

@@ -864,7 +864,6 @@ class TestMaildir(TestMailbox, unittest.TestCase):
             pass
 
     @unittest.skipUnless(hasattr(os, 'umask'), 'test needs os.umask()')
-    @unittest.skipUnless(hasattr(os, 'stat'), 'test needs os.stat()')
     def test_file_permissions(self):
         # Verify that message files are created without execute permissions
         msg = mailbox.MaildirMessage(self._template % 0)
@@ -878,7 +877,6 @@ class TestMaildir(TestMailbox, unittest.TestCase):
         self.assertFalse(mode & 0o111)
 
     @unittest.skipUnless(hasattr(os, 'umask'), 'test needs os.umask()')
-    @unittest.skipUnless(hasattr(os, 'stat'), 'test needs os.stat()')
     def test_folder_file_perms(self):
         # From bug #3228, we want to verify that the file created inside a Maildir
         # subfolder isn't marked as executable.
@@ -1120,7 +1118,6 @@ class TestMbox(_TestMboxMMDF, unittest.TestCase):
     _factory = lambda self, path, factory=None: mailbox.mbox(path, factory)
 
     @unittest.skipUnless(hasattr(os, 'umask'), 'test needs os.umask()')
-    @unittest.skipUnless(hasattr(os, 'stat'), 'test needs os.stat()')
     def test_file_perms(self):
         # From bug #3228, we want to verify that the mailbox file isn't executable,
         # even if the umask is set to something that would leave executable bits set.

Lib/test/test_mmap.py

@@ -317,7 +317,6 @@ class MmapTests(unittest.TestCase):
         mf.close()
         f.close()
 
-    @unittest.skipUnless(hasattr(os, "stat"), "needs os.stat()")
     def test_entire_file(self):
         # test mapping of entire file by passing 0 for map length
         f = open(TESTFN, "wb+")
@@ -332,7 +331,6 @@ class MmapTests(unittest.TestCase):
         mf.close()
         f.close()
 
-    @unittest.skipUnless(hasattr(os, "stat"), "needs os.stat()")
     def test_length_0_offset(self):
         # Issue #10916: test mapping of remainder of file by passing 0 for
         # map length with an offset doesn't cause a segfault.
@@ -345,7 +343,6 @@ class MmapTests(unittest.TestCase):
             with mmap.mmap(f.fileno(), 0, offset=65536, access=mmap.ACCESS_READ) as mf:
                 self.assertRaises(IndexError, mf.__getitem__, 80000)
 
-    @unittest.skipUnless(hasattr(os, "stat"), "needs os.stat()")
     def test_length_0_large_offset(self):
         # Issue #10959: test mapping of a file by passing 0 for
         # map length with a large offset doesn't cause a segfault.

Lib/test/test_os.py

@@ -238,7 +238,6 @@ class StatAttributeTests(unittest.TestCase):
         self.addCleanup(support.unlink, self.fname)
         create_file(self.fname, b"ABC")
 
-    @unittest.skipUnless(hasattr(os, 'stat'), 'test needs os.stat()')
     def check_stat_attributes(self, fname):
         result = os.stat(fname)
 

Lib/test/test_posix.py

@@ -606,8 +606,6 @@ class PosixTester(unittest.TestCase):
         finally:
             fp.close()
 
-    @unittest.skipUnless(hasattr(posix, 'stat'),
-                         'test needs posix.stat()')
     def test_stat(self):
         self.assertTrue(posix.stat(support.TESTFN))
         self.assertTrue(posix.stat(os.fsencode(support.TESTFN)))
@@ -658,7 +656,6 @@ class PosixTester(unittest.TestCase):
         except OSError as e:
             self.assertIn(e.errno, (errno.EPERM, errno.EINVAL, errno.EACCES))
 
-    @unittest.skipUnless(hasattr(posix, 'stat'), 'test needs posix.stat()')
     @unittest.skipUnless(hasattr(posix, 'makedev'), 'test needs posix.makedev()')
     def test_makedev(self):
         st = posix.stat(support.TESTFN)
@@ -755,8 +752,7 @@ class PosixTester(unittest.TestCase):
 
         # re-create the file
         support.create_empty_file(support.TESTFN)
-        self._test_all_chown_common(posix.chown, support.TESTFN,
+        self._test_all_chown_common(posix.chown, support.TESTFN, posix.stat)
-                                    getattr(posix, 'stat', None))
 
     @unittest.skipUnless(hasattr(posix, 'fchown'), "test needs os.fchown()")
     def test_fchown(self):

Lib/test/test_shutil.py

@@ -262,7 +262,6 @@ class TestShutil(unittest.TestCase):
         self.assertIn(errors[1][2][1].filename, possible_args)
 
 
-    @unittest.skipUnless(hasattr(os, 'chmod'), 'requires os.chmod()')
     @unittest.skipIf(sys.platform[:6] == 'cygwin',
                      "This test can't be run on Cygwin (issue #1071513).")
     @unittest.skipIf(hasattr(os, 'geteuid') and os.geteuid() == 0,
@@ -337,7 +336,6 @@ class TestShutil(unittest.TestCase):
         finally:
             os.lstat = orig_lstat
 
-    @unittest.skipUnless(hasattr(os, 'chmod'), 'requires os.chmod')
     @support.skip_unless_symlink
     def test_copymode_follow_symlinks(self):
         tmp_dir = self.mkdtemp()
@@ -1022,14 +1020,12 @@ class TestShutil(unittest.TestCase):
         file2 = os.path.join(tmpdir2, fname)
         return (file1, file2)
 
-    @unittest.skipUnless(hasattr(os, 'chmod'), 'requires os.chmod')
     def test_copy(self):
         # Ensure that the copied file exists and has the same mode bits.
         file1, file2 = self._copy_file(shutil.copy)
         self.assertTrue(os.path.exists(file2))
         self.assertEqual(os.stat(file1).st_mode, os.stat(file2).st_mode)
 
-    @unittest.skipUnless(hasattr(os, 'chmod'), 'requires os.chmod')
     @unittest.skipUnless(hasattr(os, 'utime'), 'requires os.utime')
     def test_copy2(self):
         # Ensure that the copied file exists and has the same mode and

Lib/test/test_tempfile.py

@@ -8,6 +8,7 @@ import sys
 import re
 import warnings
 import contextlib
+import stat
 import weakref
 from unittest import mock
 
@@ -16,12 +17,6 @@ from test import support
 from test.support import script_helper
 
 
-if hasattr(os, 'stat'):
-    import stat
-    has_stat = 1
-else:
-    has_stat = 0
-
 has_textmode = (tempfile._text_openflags != tempfile._bin_openflags)
 has_spawnl = hasattr(os, 'spawnl')
 
@@ -433,7 +428,6 @@ class TestMkstempInner(TestBadTempdir, BaseTestCase):
         finally:
             os.rmdir(dir)
 
-    @unittest.skipUnless(has_stat, 'os.stat not available')
     def test_file_mode(self):
         # _mkstemp_inner creates files with the proper mode
 
@@ -738,7 +732,6 @@ class TestMkdtemp(TestBadTempdir, BaseTestCase):
         finally:
             os.rmdir(dir)
 
-    @unittest.skipUnless(has_stat, 'os.stat not available')
     def test_mode(self):
         # mkdtemp creates directories with the proper mode
 
@@ -1221,8 +1214,7 @@ class TestSpooledTemporaryFile(BaseTestCase):
         f.write(b'abcdefg\n')
         f.truncate(20)
         self.assertTrue(f._rolled)
-        if has_stat:
+        self.assertEqual(os.fstat(f.fileno()).st_size, 20)
-            self.assertEqual(os.fstat(f.fileno()).st_size, 20)
 
 
 if tempfile.NamedTemporaryFile is not tempfile.TemporaryFile:

Misc/NEWS.d/next/Library/2019-01-21-13-56-55.bpo-35802.6633PE.rst

@@ -0,0 +1,2 @@
+Clean up code which checked presence of ``os.stat`` / ``os.lstat`` /
+``os.chmod`` which are always present.  Patch by Anthony Sottile.

setup.py

@@ -2266,7 +2266,6 @@ class PyBuildInstallLib(install_lib):
         return outfiles
 
     def set_file_modes(self, files, defaultMode, sharedLibMode):
-        if not self.is_chmod_supported(): return
         if not files: return
 
         for filename in files:
@@ -2277,16 +2276,12 @@ class PyBuildInstallLib(install_lib):
             if not self.dry_run: os.chmod(filename, mode)
 
     def set_dir_modes(self, dirname, mode):
-        if not self.is_chmod_supported(): return
         for dirpath, dirnames, fnames in os.walk(dirname):
             if os.path.islink(dirpath):
                 continue
             log.info("changing mode of %s to %o", dirpath, mode)
             if not self.dry_run: os.chmod(dirpath, mode)
 
-    def is_chmod_supported(self):
-        return hasattr(os, 'chmod')
-
 class PyBuildScripts(build_scripts):
     def copy_scripts(self):
         outfiles, updated_files = build_scripts.copy_scripts(self)