gh-155358: Use named attributes with pwd and grp modules

* Replace pwd[0] with pwd.pw_name
* Replace pwd[2] with pwd.pw_uid
* Replace grp[0] with grp.gr_name
* Replace grp[2] with grp.gr_gid

Author: vstinner

Lib/getpass.py

@@ -428,7 +428,7 @@ def getuser():
 
     try:
         import pwd
-        return pwd.getpwuid(os.getuid())[0]
+        return pwd.getpwuid(os.getuid()).pw_name
     except (ImportError, KeyError) as e:
         raise OSError('No username set in the environment') from e
 

Lib/shutil.py

@@ -983,7 +983,7 @@ def _get_gid(name):
     except KeyError:
         result = None
     if result is not None:
-        return result[2]
+        return result.gr_gid
     return None
 
 def _get_uid(name):
@@ -1001,7 +1001,7 @@ def _get_uid(name):
     except KeyError:
         result = None
     if result is not None:
-        return result[2]
+        return result.pw_uid
     return None
 
 def _make_tarball(base_name, base_dir, compress="gzip", verbose=0, dry_run=0,

Lib/tarfile.py

@@ -2282,14 +2282,14 @@ def gettarinfo(self, name=None, arcname=None, fileobj=None):
         if pwd:
             if tarinfo.uid not in self._unames:
                 try:
-                    self._unames[tarinfo.uid] = pwd.getpwuid(tarinfo.uid)[0]
+                    self._unames[tarinfo.uid] = pwd.getpwuid(tarinfo.uid).pw_name
                 except KeyError:
                     self._unames[tarinfo.uid] = ''
             tarinfo.uname = self._unames[tarinfo.uid]
         if grp:
             if tarinfo.gid not in self._gnames:
                 try:
-                    self._gnames[tarinfo.gid] = grp.getgrgid(tarinfo.gid)[0]
+                    self._gnames[tarinfo.gid] = grp.getgrgid(tarinfo.gid).gr_name
                 except KeyError:
                     self._gnames[tarinfo.gid] = ''
             tarinfo.gname = self._gnames[tarinfo.gid]
@@ -2837,12 +2837,12 @@ def chown(self, tarinfo, targetpath, numeric_owner):
             if not numeric_owner:
                 try:
                     if grp and tarinfo.gname:
-                        g = grp.getgrnam(tarinfo.gname)[2]
+                        g = grp.getgrnam(tarinfo.gname).gr_gid
                 except KeyError:
                     pass
                 try:
                     if pwd and tarinfo.uname:
-                        u = pwd.getpwnam(tarinfo.uname)[2]
+                        u = pwd.getpwnam(tarinfo.uname).pw_uid
                 except KeyError:
                     pass
             if g is None:

Lib/test/test_getpass.py

@@ -39,10 +39,13 @@ def test_username_falls_back_to_pwd(self, environ):
         expected_name = 'some_name'
         environ.get.return_value = None
         if pwd:
+            class User:
+                pass
             with mock.patch('os.getuid') as uid, \
                     mock.patch('pwd.getpwuid') as getpw:
                 uid.return_value = 42
-                getpw.return_value = [expected_name]
+                getpw.return_value = User()
+                getpw.return_value.pw_name = expected_name
                 self.assertEqual(expected_name,
                                  getpass.getuser())
                 getpw.assert_called_once_with(42)

Lib/test/test_pwd.py

@@ -50,7 +50,7 @@ def test_values_extended(self):
         # check whether the entry returned by getpwuid()
         # for each uid is among those from getpwall() for this uid
         for e in entries:
-            if not e[0] or e[0] == '+':
+            if not e.pw_name or e.pw_name == '+':
                 continue # skip NIS entries etc.
             self.assertIn(pwd.getpwnam(e.pw_name), entriesbyname[e.pw_name])
             self.assertIn(pwd.getpwuid(e.pw_uid), entriesbyuid[e.pw_uid])

Lib/test/test_shutil.py

@@ -1999,8 +1999,8 @@ def test_make_archive_owner_group(self):
         # testing make_archive with owner and group, with various combinations
         # this works even if there's not gid/uid support
         if UID_GID_SUPPORT:
-            group = grp.getgrgid(0)[0]
-            owner = pwd.getpwuid(0)[0]
+            group = grp.getgrgid(0).gr_name
+            owner = pwd.getpwuid(0).pw_name
         else:
             group = owner = 'root'
 
@@ -2027,8 +2027,8 @@ def test_make_archive_owner_group(self):
     def test_tarfile_root_owner(self):
         root_dir, base_dir = self._create_files()
         base_name = os.path.join(self.mkdtemp(), 'archive')
-        group = grp.getgrgid(0)[0]
-        owner = pwd.getpwuid(0)[0]
+        group = grp.getgrgid(0).gr_name
+        owner = pwd.getpwuid(0).pw_name
         with os_helper.change_cwd(root_dir), no_chdir:
             archive_name = make_archive(base_name, 'gztar', root_dir, 'dist',
                                         owner=owner, group=group)
@@ -2433,8 +2433,8 @@ def check_chown(path, uid=None, gid=None):
         check_chown(dirname, gid=gid)
 
         try:
-            user = pwd.getpwuid(uid)[0]
-            group = grp.getgrgid(gid)[0]
+            user = pwd.getpwuid(uid).pw_name
+            group = grp.getgrgid(gid).gr_name
         except KeyError:
             # On some systems uid/gid cannot be resolved.
             pass

Lib/test/test_tarfile.py

@@ -3351,12 +3351,12 @@ def root_is_uid_gid_0():
     except ImportError:
         return False
     try:
-        if pwd.getpwuid(0)[0] != 'root':
+        if pwd.getpwuid(0).pw_name != 'root':
             return False
     except KeyError:
         # On Cygwin, there is no root user (uid 0)
         return False
-    if grp.getgrgid(0)[0] != 'root':
+    if grp.getgrgid(0).gr_name != 'root':
         return False
     return True