1 files changed, 129 insertions, 49 deletions

diff --git a/src/plugins/ogg_extractor.c b/src/plugins/ogg_extractor.c
index a9c4f05..971ac8c 100644
--- a/src/plugins/ogg_extractor.c
+++ b/src/plugins/ogg_extractor.c
@@ -1,10 +1,10 @@
 /*
      This file is part of libextractor.
-     (C) 2002, 2003, 2009 Vidyut Samanta and Christian Grothoff
+     (C) 2002, 2003, 2009, 2012 Vidyut Samanta and Christian Grothoff
 
      libextractor is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
-     by the Free Software Foundation; either version 2, or (at your
+     by the Free Software Foundation; either version 3, or (at your
      option) any later version.
 
      libextractor is distributed in the hope that it will be useful, but
@@ -17,84 +17,162 @@
      Free Software Foundation, Inc., 59 Temple Place - Suite 330,
      Boston, MA 02111-1307, USA.
  */
-
 #include "platform.h"
 #include "extractor.h"
 #include "extractor_plugins.h"
+#include <vorbis/vorbisfile.h>
 
-#define DEBUG_EXTRACT_OGG 0
+/**
+ * Bytes each ogg file must begin with (not used, but we might
+ * choose to add this back in the future to improve performance
+ * for non-ogg files).
+ */
 #define OGG_HEADER 0x4f676753
 
-#if HAVE_VORBIS_VORBISFILE_H
-#include <vorbis/vorbisfile.h>
-#else
-#error You must install the libvorbis header files!
-#endif
-
-static char *
-get_comment (vorbis_comment * vc, char *label)
-{
-  char *tag;
-  if (vc && (tag = vorbis_comment_query (vc, label, 0)) != NULL)
-    return tag;
-  return NULL;
-}
 
+/**
+ * Custom read function for ogg.
+ *
+ * @param ptr where to write the data
+ * @param size number of bytes to read per member
+ * @param nmemb number of members to read
+ * @param datasource the 'struct EXTRACTOR_ExtractContext'
+ * @return 0 on end-of-data, 0 with errno set to indicate read error
+ */
 static size_t
-readOgg (void *ptr, size_t size, size_t nmemb, void *datasource)
+read_ogg (void *ptr, size_t size, size_t nmemb, void *datasource)
 {
-  struct EXTRACTOR_PluginList *plugin = datasource;
-  int64_t ret;
-  unsigned char *read_data;
+  struct EXTRACTOR_ExtractContext *ec = datasource;
+  void *data;
+  ssize_t ret;
 
-  ret = pl_read (plugin, &read_data, size*nmemb);
-  if (ret <= 0)
-  {
-    if (ret < 0)
-      errno = EIO;
+  data = NULL;
+  ret = ec->read (ec->cls,
+                  &data,
+                  size * nmemb);
+  if (-1 == ret)
     return 0;
-  }
-  memcpy (ptr, read_data, ret);
+  if (0 == ret)
+    {
+      errno = 0;
+      return 0;
+    }
+  memcpy (ptr, data, ret);
+  errno = 0;
   return ret;
 }
 
-#define ADD(t,s) do { if (0 != (ret = proc (proc_cls, "ogg", t, EXTRACTOR_METAFORMAT_UTF8, "text/plain", s, strlen(s)+1))) goto FINISH; } while (0)
 
-#define ADDG(t,d) do { m = get_comment (comments, d); if (m != NULL) ADD(t,m); } while (0)
+/**
+ * Seek to a particular position in the file.
+ *
+ * @param datasource  the 'struct EXTRACTOR_ExtractContext'
+ * @param offset where to seek
+ * @param whence how to seek
+ * @return -1 on error
+ */
+static int 
+seek_ogg (void *datasource,
+          ogg_int64_t offset,
+          int whence)
+{
+  struct EXTRACTOR_ExtractContext *ec = datasource;
+
+  if (-1 == ec->seek (ec->cls,
+                      (int64_t) offset,
+                      whence))
+    return -1;
+  return 0;
+}
+
+
+/**
+ * Tell ogg where we are in the file
+ *
+ * @param datasource  the 'struct EXTRACTOR_ExtractContext'
+ * @return 
+ */
+static long
+tell_ogg (void *datasource)
+{
+  struct EXTRACTOR_ExtractContext *ec = datasource;
+
+  return (long) ec->seek (ec->cls,
+                          0,
+                          SEEK_CUR);
+}
+
+
+
+/**
+ * Extract the associated meta data for a given label from vorbis.
+ *
+ * @param vc vorbis comment data
+ * @param label label marking the desired entry
+ * @return NULL on error, otherwise the meta data
+ */
+static char *
+get_comment (vorbis_comment *vc, 
+             const char *label)
+{
+  if (NULL == vc)
+    return NULL;
+  return vorbis_comment_query (vc, label, 0);
+}
+
+
+/**
+ * Extract meta data from vorbis using the given LE type and value.
+ *
+ * @param t LE meta data type
+ * @param s meta data to add
+ */
+#define ADD(t,s) do { if (0 != (ret = ec->proc (ec->cls, "ogg", t, EXTRACTOR_METAFORMAT_UTF8, "text/plain", s, strlen(s)+1))) goto FINISH; } while (0)
+
+
+/**
+ * Extract meta data from vorbis using the given LE type and label.
+ *
+ * @param t LE meta data type
+ * @param d vorbis meta data label
+ */
+#define ADDG(t,d) do { m = get_comment (comments, d); if (NULL != m) ADD(t,m); } while (0)
+
 
-/* mimetype = application/ogg */
-int
-EXTRACTOR_ogg_extract_method (struct EXTRACTOR_PluginList *plugin,
-    EXTRACTOR_MetaDataProcessor proc, void *proc_cls)
+/**
+ * Main entry method for the 'application/ogg' extraction plugin.
+ *
+ * @param ec extraction context provided to the plugin
+ */
+void
+EXTRACTOR_ogg_extract_method (struct EXTRACTOR_ExtractContext *ec)
 {
+  uint64_t fsize;
+  ov_callbacks callbacks;
   OggVorbis_File vf;
   vorbis_comment *comments;
-  ov_callbacks callbacks;
   int ret;
-  int64_t fsize;
   const char *m;
 
-  fsize = pl_get_fsize (plugin);
-  if (fsize > 0 && fsize < 2 * sizeof (int))
-    return 1;
-  if (fsize == 0)
-    return 1;
+  fsize = ec->get_size (ec->cls);
+  if (fsize < 8)
+    return;
 
   /* TODO: rewrite pl_seek() to be STDIO-compatible (SEEK_END) and enable seeking. */
-  callbacks.read_func = &readOgg;
-  callbacks.seek_func = NULL;
+  callbacks.read_func = &read_ogg;
+  callbacks.seek_func = &seek_ogg;
   callbacks.close_func = NULL;
-  callbacks.tell_func = NULL;
-  if (0 != ov_open_callbacks (plugin, &vf, NULL, 0, callbacks))
+  callbacks.tell_func = &tell_ogg;
+  if (0 != ov_open_callbacks (ec, &vf, NULL, 0, callbacks))
   {
     ov_clear (&vf);
-    return 1;
+    return;
   }
   comments = ov_comment (&vf, -1);
   if (NULL == comments)
   {
     ov_clear (&vf);
-    return 1;
+    return;
   }
   ret = 0;
   ADD (EXTRACTOR_METATYPE_MIMETYPE, "application/ogg");
@@ -119,5 +197,7 @@ EXTRACTOR_ogg_extract_method (struct EXTRACTOR_PluginList *plugin,
   ADDG (EXTRACTOR_METATYPE_SONG_VERSION, "version");
 FINISH:
   ov_clear (&vf);
-  return 1;
 }
+
+/* end of ogg_extractor.c */
+