[gnome-desktop] Determine the correct mime type when we still know the filename

[William Jon McCann <mccann src gnome org>]

commit 6c4d2acee563d3f3590edbccca26ec01f2fc2fd9
Author: William Jon McCann <jmccann redhat com>
Date:   Wed Aug 15 15:48:34 2012 -0400

    Determine the correct mime type when we still know the filename
    
    This fixes the case where we want to load .svgz files. If we
    just sniff the data we'll determine that they are application/gzip.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=655406

 libgnome-desktop/gnome-desktop-thumbnail.c |   75 ++++++++++++++++++++++-----
 1 files changed, 61 insertions(+), 14 deletions(-)
---
diff --git a/libgnome-desktop/gnome-desktop-thumbnail.c b/libgnome-desktop/gnome-desktop-thumbnail.c
index 1219947..daf8ed5 100644
--- a/libgnome-desktop/gnome-desktop-thumbnail.c
+++ b/libgnome-desktop/gnome-desktop-thumbnail.c
@@ -298,6 +298,39 @@ size_prepared_cb (GdkPixbufLoader *loader,
   gdk_pixbuf_loader_set_size (loader, width, height);
 }
 
+static GdkPixbufLoader *
+create_loader (GFile        *file,
+               const guchar *data,
+               gsize         size)
+{
+  GdkPixbufLoader *loader;
+  GError *error = NULL;
+  char *mime_type;
+  char *filename;
+
+  loader = NULL;
+
+  /* need to specify the type here because the gdk_pixbuf_loader_write
+     doesn't have access to the filename in order to correct detect
+     the image type. */
+  filename = g_file_get_basename (file);
+  mime_type = g_content_type_guess (filename, data, size, NULL);
+  g_free (filename);
+
+  if (mime_type != NULL) {
+    loader = gdk_pixbuf_loader_new_with_mime_type (mime_type, &error);
+  }
+
+  if (loader == NULL) {
+    g_warning ("Unable to create loader for mime type %s: %s", mime_type, error->message);
+    g_clear_error (&error);
+    loader = gdk_pixbuf_loader_new ();
+  }
+  g_free (mime_type);
+
+  return loader;
+}
+
 static GdkPixbuf *
 _gdk_pixbuf_new_from_uri_at_scale (const char *uri,
 				   gint        width,
@@ -305,9 +338,9 @@ _gdk_pixbuf_new_from_uri_at_scale (const char *uri,
 				   gboolean    preserve_aspect_ratio)
 {
     gboolean result;
-    char buffer[LOAD_BUFFER_SIZE];
+    guchar buffer[LOAD_BUFFER_SIZE];
     gsize bytes_read;
-    GdkPixbufLoader *loader;
+    GdkPixbufLoader *loader = NULL;
     GdkPixbuf *pixbuf;	
     GdkPixbufAnimation *animation;
     GdkPixbufAnimationIter *iter;
@@ -316,6 +349,7 @@ _gdk_pixbuf_new_from_uri_at_scale (const char *uri,
     GFile *file;
     GFileInfo *file_info;
     GInputStream *input_stream;
+    GError *error = NULL;
 
     g_return_val_if_fail (uri != NULL, NULL);
 
@@ -345,22 +379,17 @@ _gdk_pixbuf_new_from_uri_at_scale (const char *uri,
     }
 
     if (input_stream == NULL) {
-        input_stream = gs_file_read_noatime (file, NULL, NULL);
+        input_stream = gs_file_read_noatime (file, NULL, &error);
         if (input_stream == NULL) {
+            if (error != NULL) {
+                g_warning ("Unable to create an input stream for %s: %s", uri, error->message);
+                g_clear_error (&error);
+            }
 	    g_object_unref (file);
             return NULL;
         }
     }
 
-    loader = gdk_pixbuf_loader_new ();
-    if (1 <= width || 1 <= height) {
-        info.width = width;
-        info.height = height;
-	info.input_width = info.input_height = 0;
-        info.preserve_aspect_ratio = preserve_aspect_ratio;        
-        g_signal_connect (loader, "size-prepared", G_CALLBACK (size_prepared_cb), &info);
-    }
-
     has_frame = FALSE;
 
     result = FALSE;
@@ -370,7 +399,11 @@ _gdk_pixbuf_new_from_uri_at_scale (const char *uri,
 					  buffer,
 					  sizeof (buffer),
 					  NULL,
-					  NULL);
+					  &error);
+        if (error != NULL) {
+            g_warning ("Error reading from %s: %s", uri, error->message);
+            g_clear_error (&error);
+        }
 	if (bytes_read == -1) {
 	    break;
 	}
@@ -379,10 +412,24 @@ _gdk_pixbuf_new_from_uri_at_scale (const char *uri,
 	    break;
 	}
 
+        if (loader == NULL) {
+            loader = create_loader (file, buffer, bytes_read);
+            if (1 <= width || 1 <= height) {
+              info.width = width;
+              info.height = height;
+              info.input_width = info.input_height = 0;
+              info.preserve_aspect_ratio = preserve_aspect_ratio;
+              g_signal_connect (loader, "size-prepared", G_CALLBACK (size_prepared_cb), &info);
+            }
+            g_assert (loader != NULL);
+        }
+
 	if (!gdk_pixbuf_loader_write (loader,
 				      (unsigned char *)buffer,
 				      bytes_read,
-				      NULL)) {
+				      &error)) {
+            g_warning ("Error creating thumbnail for %s: %s", uri, error->message);
+            g_clear_error (&error);
 	    result = FALSE;
 	    break;
 	}