[tracker] tracker-extract: Add Gibest hash calculation to GStreamer

[Bastien Nocera <hadess src gnome org>]

commit 83023a82080064faa2aa788935b48aad305933e2
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Mar 18 16:39:49 2014 +0100

    tracker-extract: Add Gibest hash calculation to GStreamer
    
    Add Gibest extract to GStreamer extractor, as used in the
    OpenSubtitles service:
    http://trac.opensubtitles.org/projects/opensubtitles/wiki/HashSourceCodes
    
    extract_gibest_hash() written by Carlos Garnacho <carlosg gnome org>
    
    https://bugzilla.gnome.org/show_bug.cgi?id=726640

 src/tracker-extract/tracker-extract-gstreamer.c |   82 +++++++++++++++++++++++
 1 files changed, 82 insertions(+), 0 deletions(-)
---
diff --git a/src/tracker-extract/tracker-extract-gstreamer.c b/src/tracker-extract/tracker-extract-gstreamer.c
index ca03d1f..1157a8b 100644
--- a/src/tracker-extract/tracker-extract-gstreamer.c
+++ b/src/tracker-extract/tracker-extract-gstreamer.c
@@ -1063,6 +1063,57 @@ delete_existing_tracks (TrackerSparqlBuilder *postupdate,
        g_free (sparql);
 }
 
+#define CHUNK_N_BYTES (2 << 15)
+
+static guint64
+extract_gibest_hash (GFile *file)
+{
+       guint64 buffer[2][CHUNK_N_BYTES/8];
+       GInputStream *stream = NULL;
+       gssize n_bytes, file_size;
+       GError *error = NULL;
+       guint64 hash = 0;
+       gint i;
+
+       stream = G_INPUT_STREAM (g_file_read (file, NULL, &error));
+       if (stream == NULL)
+               goto fail;
+
+       /* Extract start/end chunks of the file */
+       n_bytes = g_input_stream_read (stream, buffer[0], CHUNK_N_BYTES, NULL, &error);
+       if (n_bytes == -1)
+               goto fail;
+
+       if (!g_seekable_seek (G_SEEKABLE (stream), -CHUNK_N_BYTES, G_SEEK_END, NULL, &error))
+               goto fail;
+
+       n_bytes = g_input_stream_read (stream, buffer[1], CHUNK_N_BYTES, NULL, &error);
+       if (n_bytes == -1)
+               goto fail;
+
+       for (i = 0; i < G_N_ELEMENTS (buffer[0]); i++)
+               hash += buffer[0][i] + buffer[1][i];
+
+       file_size = g_seekable_tell (G_SEEKABLE (stream));
+
+       if (file_size < CHUNK_N_BYTES)
+               goto end;
+
+       /* Include file size */
+       hash += file_size;
+       g_object_unref (stream);
+
+       return hash;
+
+fail:
+       g_warning ("Could not get file hash: %s\n", error ? error->message : "Unknown error");
+       g_clear_error (&error);
+
+end:
+       g_clear_object (&stream);
+       return 0;
+}
+
 static void
 extract_metadata (MetadataExtractor      *extractor,
                   const gchar            *file_url,
@@ -1239,6 +1290,37 @@ extract_metadata (MetadataExtractor      *extractor,
                g_free (album_artist_uri);
        }
 
+       /* OpenSubtitles compatible hash */
+       if (extractor->mime == EXTRACT_MIME_VIDEO) {
+               guint64 hash;
+               GFile *file;
+
+               file = g_file_new_for_uri (file_url);
+               hash = extract_gibest_hash (file);
+               g_object_unref (file);
+
+               if (hash) {
+                       char *hash_str;
+
+                       /* { <foo> a nfo:FileHash; nfo:hashValue "..."; nfo:hashAlgorithm "gibest" } */
+                       tracker_sparql_builder_predicate (metadata, "nfo:hasHash");
+
+                       tracker_sparql_builder_object_blank_open (metadata);
+                       tracker_sparql_builder_predicate (metadata, "a");
+                       tracker_sparql_builder_object (metadata, "nfo:FileHash");
+
+                       tracker_sparql_builder_predicate (metadata, "nfo:hashValue");
+                       hash_str = g_strdup_printf ("%" G_GSIZE_MODIFIER "x", hash);
+                       tracker_sparql_builder_object_string (metadata, hash_str);
+                       g_free (hash_str);
+
+                       tracker_sparql_builder_predicate (metadata, "nfo:hashAlgorithm");
+                       tracker_sparql_builder_object_string (metadata, "gibest");
+
+                       tracker_sparql_builder_object_blank_close (metadata);
+               }
+       }
+
        /* If content was encrypted, set it. */
 /* #warning TODO: handle encrypted content with the Discoverer/GUPnP-DLNA backends */