typefind: add detection for windows icon files to get them out of the way

Some of them can otherwise be misdetected for MPEG audio.

https://bugzilla.gnome.org/show_bug.cgi?id=620364

diff --git a/gst/typefind/gsttypefindfunctions.c b/gst/typefind/gsttypefindfunctions.c
index 373df08..afdff15 100644 (file)
--- a/gst/typefind/gsttypefindfunctions.c
+++ b/gst/typefind/gsttypefindfunctions.c
@@ -3869,6 +3869,48 @@ xdgmime_typefind (GstTypeFind * find, gpointer user_data)
 }
 #endif /* USE_GIO */
 
+/*** Windows icon typefinder (to avoid false positives mostly) ***/
+
+static void
+windows_icon_typefind (GstTypeFind * find, gpointer user_data)
+{
+  guint8 *data;
+  gint64 datalen;
+  guint16 type, nimages;
+  gint32 size, offset;
+
+  datalen = gst_type_find_get_length (find);
+  if ((data = gst_type_find_peek (find, 0, 6)) == NULL)
+    return;
+
+  /* header - simple and not enough to rely on it alone */
+  if (GST_READ_UINT16_LE (data) != 0)
+    return;
+  type = GST_READ_UINT16_LE (data + 2);
+  if (type != 1 && type != 2)
+    return;
+  nimages = GST_READ_UINT16_LE (data + 4);
+  if (nimages == 0)             /* we can assume we can't have an empty image file ? */
+    return;
+
+  /* first image */
+  if (data[6 + 3] != 0)
+    return;
+  if (type == 1) {
+    guint16 planes = GST_READ_UINT16_LE (data + 6 + 4);
+    if (planes > 1)
+      return;
+  }
+  size = GST_READ_UINT32_LE (data + 6 + 8);
+  offset = GST_READ_UINT32_LE (data + 6 + 12);
+  if (offset < 0 || size <= 0 || size >= datalen || offset >= datalen
+      || size + offset > datalen)
+    return;
+
+  gst_type_find_suggest_simple (find, GST_TYPE_FIND_NEARLY_CERTAIN,
+      "image/vnd.microsoft.icon", NULL);
+}
+
 /*** generic typefind for streams that have some data at a specific position***/
 typedef struct
 {
@@ -4332,6 +4374,8 @@ plugin_init (GstPlugin * plugin)
       GST_TYPE_FIND_LIKELY);
   TYPE_FIND_REGISTER_START_WITH (plugin, "application/x-yuv4mpeg",
       GST_RANK_SECONDARY, y4m_exts, "YUV4MPEG2 ", 10, GST_TYPE_FIND_LIKELY);
+  TYPE_FIND_REGISTER (plugin, "image/vnd.microsoft.icon", GST_RANK_MARGINAL,
+      windows_icon_typefind, NULL, NULL, NULL, NULL);
 
 #ifdef USE_GIO
   TYPE_FIND_REGISTER (plugin, "xdgmime-base", GST_RANK_MARGINAL,