[gtk+] recent-manager: Add a limit to the list's size

[Matthias Clasen <matthiasc src gnome org>]

commit 0d364173f61feb4d089eaa95ace9c1cc13681339
Author: Lauri Kasanen <curaga operamail com>
Date:   Thu Oct 27 16:51:29 2016 +0300

    recent-manager: Add a limit to the list's size
    
    This fixes a DOS where any app can cause all running gtk apps
    to use arbitrary amounts of memory.
    
    Originally reported against mate-panel, where running a big slideshow
    in eye-of-mate caused increasing RAM usage in mate-panel.
    
    v2: Hardcode the value
    Signed-off-by: Lauri Kasanen <curaga operamail com>
    
    https://bugzilla.gnome.org/show_bug.cgi?id=773587

 gtk/gtkrecentmanager.c |   43 ++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 40 insertions(+), 3 deletions(-)
---
diff --git a/gtk/gtkrecentmanager.c b/gtk/gtkrecentmanager.c
index 1157eec..fe5f03f 100644
--- a/gtk/gtkrecentmanager.c
+++ b/gtk/gtkrecentmanager.c
@@ -113,6 +113,9 @@
 /* return all items by default */
 #define DEFAULT_LIMIT   -1
 
+/* limit the size of the list */
+#define MAX_LIST_SIZE 1000
+
 /* keep in sync with xdgmime */
 #define GTK_RECENT_DEFAULT_MIME "application/octet-stream"
 
@@ -211,6 +214,9 @@ static void     gtk_recent_manager_set_filename        (GtkRecentManager  *manag
                                                         const gchar       *filename);
 static void     gtk_recent_manager_clamp_to_age        (GtkRecentManager  *manager,
                                                         gint               age);
+static void     gtk_recent_manager_clamp_to_size       (GtkRecentManager  *manager,
+                                                        const gint         size);
+
 static void     gtk_recent_manager_enabled_changed     (GtkRecentManager  *manager);
 
 
@@ -462,6 +468,7 @@ gtk_recent_manager_real_changed (GtkRecentManager *manager)
         {
           GtkSettings *settings;
           gint age;
+          gint max_size = MAX_LIST_SIZE;
           gboolean enabled;
 
           settings = gtk_settings_get_default ();
@@ -476,14 +483,19 @@ gtk_recent_manager_real_changed (GtkRecentManager *manager)
               enabled = TRUE;
             }
 
-          if (age == 0 || !enabled)
+          if (age == 0 || max_size == 0 || !enabled)
             {
               g_bookmark_file_free (priv->recent_items);
               priv->recent_items = g_bookmark_file_new ();
               priv->size = 0;
             }
-          else if (age > 0)
-            gtk_recent_manager_clamp_to_age (manager, age);
+          else
+            {
+              if (age > 0)
+                gtk_recent_manager_clamp_to_age (manager, age);
+              if (max_size > 0)
+                gtk_recent_manager_clamp_to_size (manager, max_size);
+            }
         }
 
       if (priv->filename != NULL)
@@ -1455,6 +1467,31 @@ gtk_recent_manager_clamp_to_age (GtkRecentManager *manager,
   g_strfreev (uris);
 }
 
+static void
+gtk_recent_manager_clamp_to_size (GtkRecentManager *manager,
+                                  const gint        size)
+{
+  GtkRecentManagerPrivate *priv = manager->priv;
+  gchar **uris;
+  gsize n_uris, i;
+
+  if (G_UNLIKELY (!priv->recent_items) || G_UNLIKELY (size < 0))
+    return;
+
+  uris = g_bookmark_file_get_uris (priv->recent_items, &n_uris);
+
+  if (n_uris < size)
+    return;
+
+  for (i = 0; i < n_uris - size; i++)
+    {
+      const gchar *uri = uris[i];
+      g_bookmark_file_remove_item (priv->recent_items, uri, NULL);
+    }
+
+  g_strfreev (uris);
+}
+
 /*****************
  * GtkRecentInfo *
  *****************/