[rygel] media-export: Add some checks for user-provided virtual ids

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit df15a59857ff2c830c93f701a37aa1c49a8c56ff
Author: Jens Georg <mail jensge org>
Date:   Sun Mar 14 12:13:52 2010 +0100

    media-export: Add some checks for user-provided virtual ids

 .../rygel-media-export-query-container.vala        |   37 ++++++++++++++++++++
 .../rygel-media-export-root-container.vala         |    7 ++++
 2 files changed, 44 insertions(+), 0 deletions(-)
---
diff --git a/src/plugins/media-export/rygel-media-export-query-container.vala b/src/plugins/media-export/rygel-media-export-query-container.vala
index 2a77105..0329abb 100644
--- a/src/plugins/media-export/rygel-media-export-query-container.vala
+++ b/src/plugins/media-export/rygel-media-export-query-container.vala
@@ -29,6 +29,43 @@ internal class Rygel.MediaExportQueryContainer : Rygel.MediaDBContainer {
     public string plaintext_id;
     private string pattern = "";
 
+    /**
+     * Simple check for validity of user-supplied virtual folder id
+     *
+     * @param id to check
+     * @return true, if id passes, false otherwise
+     */
+    public static bool validate_virtual_id (string id) {
+        if (! id.has_prefix (PREFIX)) {
+
+            return false;
+        }
+
+        var args = id.split(",");
+
+        if ((args.length % 2) != 0) {
+            warning ("Id does not contain pairs");
+
+            return false;
+        }
+
+        for (int i = 0; i < args.length; i += 2) {
+            if (args[i] == "" || args[i + 1] == "") {
+                warning ("Empty part not allowed in virtual id");
+
+                return false;
+            }
+
+            if (args[i] == "?") {
+                warning ("Placeholder can only be on second place");
+
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     public MediaExportQueryContainer (MediaDB media_db,
                                       string  id,
                                       string  name) {
diff --git a/src/plugins/media-export/rygel-media-export-root-container.vala b/src/plugins/media-export/rygel-media-export-root-container.vala
index 19719fd..12c0d68 100644
--- a/src/plugins/media-export/rygel-media-export-root-container.vala
+++ b/src/plugins/media-export/rygel-media-export-root-container.vala
@@ -289,6 +289,13 @@ public class Rygel.MediaExportRootContainer : Rygel.MediaDBContainer {
             foreach (var container in virtual_containers) {
                 var info = container.split ("=");
                 var id = MediaExportQueryContainer.PREFIX + info[1];
+                if (!MediaExportQueryContainer.validate_virtual_id (id)) {
+                    warning ("%s is not a valid virtual id", id);
+
+                    continue;
+                }
+                id = MediaExportQueryContainer.register_id (id);
+
                 var virtual_container = new MediaExportQueryContainer (
                                         this.media_db,
                                         id,