[gdm] display-access-file: maintain FamilyLocal entry for backward compatibility

[Ray Strode <halfline src gnome org>]

commit 6bc39aa208dbd8105232ae62255c42fafdec0541
Author: Ray Strode <rstrode redhat com>
Date:   Thu Dec 20 11:07:09 2012 -0500

    display-access-file: maintain FamilyLocal entry for backward compatibility
    
    commit 0fccf4e0671e49f6e57d0135c97344973c042b23 swapped out the
    FamilyLocal auth cookie for a FamilyWild auth cookie, because the
    latter is more resilient to hostname changes.  Unfortunately,
    not all of the tooling accepts FamilyWild cookies (in particular the
    xauth command), so things like su broke.
    
    This commit changes the code to have a FamilyWild and FamilyLocal
    cookie.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=690562

 daemon/gdm-display-access-file.c |   64 +++++++++++++++++++++++++++++++------
 1 files changed, 53 insertions(+), 11 deletions(-)
---
diff --git a/daemon/gdm-display-access-file.c b/daemon/gdm-display-access-file.c
index 02bd414..02ec0a0 100644
--- a/daemon/gdm-display-access-file.c
+++ b/daemon/gdm-display-access-file.c
@@ -438,8 +438,18 @@ _get_auth_info_for_display (GdmDisplayAccessFile *file,
         gdm_display_is_local (display, &is_local, NULL);
 
         if (is_local) {
-                *family = FamilyWild;
-                *address = g_strdup ("localhost");
+                /* We could just use FamilyWild here except xauth
+                 * (and by extension su and ssh) doesn't support it yet
+                 *
+                 * https://bugs.freedesktop.org/show_bug.cgi?id=43425
+                 */
+                char localhost[HOST_NAME_MAX + 1] = "";
+                *family = FamilyLocal;
+                if (gethostname (localhost, HOST_NAME_MAX) == 0) {
+                        *address = g_strdup (localhost);
+                } else {
+                        *address = g_strdup ("localhost");
+                }
         } else {
                 *family = FamilyWild;
                 gdm_display_get_remote_hostname (display, address, NULL);
@@ -533,6 +543,18 @@ gdm_display_access_file_add_display_with_cookie (GdmDisplayAccessFile  *file,
                 display_added = TRUE;
         }
 
+        /* If we wrote a FamilyLocal entry, we still want a FamilyWild
+         * entry, because it's more resiliant against hostname changes
+         *
+         */
+        if (auth_entry.family == FamilyLocal) {
+                auth_entry.family = FamilyWild;
+
+                if (XauWriteAuth (file->priv->fp, &auth_entry)
+                    && fflush (file->priv->fp) != EOF) {
+                        display_added = TRUE;
+                }
+        }
 
         g_free (auth_entry.address);
         g_free (auth_entry.number);
@@ -555,6 +577,7 @@ gdm_display_access_file_remove_display (GdmDisplayAccessFile  *file,
         unsigned short  name_length;
         char           *name;
 
+        gboolean        result = FALSE;
 
         g_return_val_if_fail (file != NULL, FALSE);
         g_return_val_if_fail (file->priv->path != NULL, FALSE);
@@ -579,25 +602,44 @@ gdm_display_access_file_remove_display (GdmDisplayAccessFile  *file,
         g_free (number);
         g_free (name);
 
-        if (auth_entry == NULL) {
+        if (auth_entry != NULL) {
+                XauDisposeAuth (auth_entry);
+                result = TRUE;
+        }
+
+        /* If FamilyLocal, we also added a FamilyWild entry,
+         * so we need to clean that up too
+         */
+        if (family == FamilyLocal) {
+                auth_entry = XauGetAuthByAddr (FamilyWild,
+                                               address_length,
+                                               address,
+                                               number_length,
+                                               number,
+                                               name_length,
+                                               name);
+
+                if (auth_entry != NULL) {
+                        XauDisposeAuth (auth_entry);
+                        result = TRUE;
+                }
+        }
+
+
+        if (result == FALSE) {
                 g_set_error (error,
                              GDM_DISPLAY_ACCESS_FILE_ERROR,
                              GDM_DISPLAY_ACCESS_FILE_ERROR_FINDING_AUTH_ENTRY,
                              "could not find authorization entry");
-                return FALSE;
-        }
-
-        XauDisposeAuth (auth_entry);
-
-        if (fflush (file->priv->fp) == EOF) {
+        } else if (fflush (file->priv->fp) == EOF) {
                 g_set_error (error,
                              G_FILE_ERROR,
                              g_file_error_from_errno (errno),
                              "%s", g_strerror (errno));
-                return FALSE;
+                result = FALSE;
         }
 
-        return TRUE;
+        return result;
 }
 
 void