+static uint
+get_ancestral_uid (uint pid)
+{
+ FILE *fp;
+ char buf [80];
+ int ppid = 0;
+ int uid = 0;
+ gboolean got_ppid = 0;
+ gboolean got_uid = 0;
+
+ sprintf (buf, "/proc/%d/status", pid);
+ fp = fopen (buf, "r");
+ if (!fp)
+ return 0;
+ while ((!got_ppid || !got_uid) && fgets (buf, sizeof (buf), fp))
+ {
+ if (sscanf (buf, "PPid:\t%d", &ppid) == 1)
+ got_ppid = TRUE;
+ else if (sscanf (buf, "Uid:\t%d", &uid) == 1)
+ got_uid = TRUE;
+ }
+ fclose (fp);
+
+ if (!got_ppid || !got_uid)
+ return 0;
+ if (uid != 0)
+ return uid;
+ if (ppid == 0 || ppid == 1)
+ return 0;
+ return get_ancestral_uid (ppid);
+}
+
+static dbus_bool_t
+user_check (DBusConnection *bus, unsigned long uid)
+{
+ if (uid == getuid () || uid == geteuid ())
+ return TRUE;
+ if (getuid () == 0)
+ return get_ancestral_uid (getpid ()) == uid;
+ return FALSE;
+}
+