Add user and group wrappers

New classes for user and group names provide a convenient way to access
the uid and primary gid of a user / gid of a group. The classes also
provide chown() and chgrp() methods to simplify common operations.

The wrappers are subclasses of builtin str type and behave like ordinary
strings with additional features. The pwd and grp structs are retrieved
once and then cached.

Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipaserver/install/server/upgrade.py

@@ -11,7 +11,6 @@ import re
 import os
 import glob
 import shutil
-import pwd
 import fileinput
 import ssl
 import stat
@@ -755,8 +754,7 @@ def copy_crl_file(old_path, new_path=None):
         os.symlink(realpath, new_path)
     else:
         shutil.copy2(old_path, new_path)
-        pent = pwd.getpwnam(constants.PKI_USER)
-        os.chown(new_path, pent.pw_uid, pent.pw_gid)
+        constants.PKI_USER.chown(new_path)
 
     tasks.restore_context(new_path)
 
@@ -1104,8 +1102,7 @@ def update_http_keytab(http):
                 'Cannot remove file %s (%s). Please remove the file manually.',
                 paths.OLD_IPA_KEYTAB, e
             )
-    pent = pwd.getpwnam(http.keytab_user)
-    os.chown(http.keytab, pent.pw_uid, pent.pw_gid)
+    http.keytab_user.chown(http.keytab)
 
 
 def ds_enable_sidgen_extdom_plugins(ds):