core: Look up live user from PKEXEC_UID

anaconda can be run as gnome-initial-setup or liveuser on live
images, depending on how its started by the use.

It currently assumes it will be started as liveuser always.

This commit makes it look up the username and home directory by
querying PKEXEC_UID environment variable.

pyanaconda/core/live_user.py

@@ -20,7 +20,7 @@
 #
 
 from collections import namedtuple
-from pwd import getpwnam
+from pwd import getpwuid
 
 from pyanaconda.core.configuration.anaconda import conf
 
@@ -38,13 +38,17 @@ def get_live_user():
         return None
 
     try:
-        username = "liveuser"
-        uid = getpwnam(username).pw_uid
+        if not "PKEXEC_UID" in os.environ:
+            return None
+        uid = int(os.environ.get("PKEXEC_UID"))
+        passwd_entry = getpwuid(uid)
+        username = passwd_entry.pw_name
+        home_dir = passwd_entry.pw_dir
         env_prune = ("GDK_BACKEND",)
         env_add = {
             "XDG_RUNTIME_DIR": "/run/user/{}".format(uid),
             "USER": username,
-            "HOME": "/home/{}".format(username),
+            "HOME": home_dir,
         }
         return User(name=username,
                     uid=uid,

tests/unit_tests/pyanaconda_tests/core/test_live_user.py

@@ -17,6 +17,7 @@
 # Red Hat, Inc.
 #
 
+import os
 from unittest import TestCase
 from unittest.mock import patch, Mock
 from pyanaconda.core.live_user import get_live_user, User
@@ -25,16 +26,17 @@
 class GetLiveUserTests(TestCase):
 
     @patch("pyanaconda.core.live_user.conf")
-    @patch("pyanaconda.core.live_user.getpwnam")
-    def test_get_live_user(self, getpwnam_mock, conf_mock):
+    @patch("pyanaconda.core.live_user.getpwuid")
+    def test_get_live_user(self, getpwuid_mock, conf_mock):
         # not live = early exit
         conf_mock.system.provides_liveuser = False
         assert get_live_user() is None
-        getpwnam_mock.assert_not_called()
+        getpwuid_mock.assert_not_called()
 
         # live and has user
         conf_mock.system.provides_liveuser = True
-        getpwnam_mock.return_value = Mock(pw_uid=1024)
+        os.environ['PKEXEC_UID']=1024
+        getpwuid_mock.return_value = Mock(pw_uid=1024, pw_dir='/home/liveuser', pw_name='liveuser')
         assert get_live_user() == User(name="liveuser",
                                        uid=1024,
                                        env_prune=("GDK_BACKEND",),
@@ -43,10 +45,10 @@ def test_get_live_user(self, getpwnam_mock, conf_mock):
                                            "USER": "liveuser",
                                            "HOME": "/home/liveuser",
                                        })
-        getpwnam_mock.assert_called_once_with("liveuser")
-        getpwnam_mock.reset_mock()
+        getpwuid_mock.assert_called_once_with("liveuser")
+        getpwuid_mock.reset_mock()
 
         # supposedly live but missing user
-        getpwnam_mock.side_effect = KeyError
+        getpwuid_mock.side_effect = KeyError
         assert get_live_user() is None
-        getpwnam_mock.assert_called_once_with("liveuser")
+        getpwuid_mock.assert_called_once_with("liveuser")