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/*
This file is part of libextractor.
Copyright (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 3, or (at your
option) any later version.
libextractor is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with libextractor; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
/**
* @file plugins/ogg_extractor.c
* @brief plugin to support OGG files
* @author Christian Grothoff
*/
#include "platform.h"
#include "extractor.h"
#include <vorbis/vorbisfile.h>
/**
* 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
/**
* 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
read_ogg (void *ptr, size_t size, size_t nmemb, void *datasource)
{
struct EXTRACTOR_ExtractContext *ec = datasource;
void *data;
ssize_t ret;
data = NULL;
ret = ec->read (ec->cls,
&data,
size * nmemb);
if (-1 == ret)
return 0;
if (0 == ret)
{
errno = 0;
return 0;
}
memcpy (ptr, data, ret);
errno = 0;
return ret;
}
/**
* 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, new position on success
*/
static int
seek_ogg (void *datasource,
ogg_int64_t offset,
int whence)
{
struct EXTRACTOR_ExtractContext *ec = datasource;
int64_t new_position;
new_position = ec->seek (ec->cls, (int64_t) offset, whence);
return (long) new_position;
}
/**
* 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)
/**
* 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;
int ret;
const char *m;
fsize = ec->get_size (ec->cls);
if (fsize < 8)
return;
callbacks.read_func = &read_ogg;
callbacks.seek_func = &seek_ogg;
callbacks.close_func = NULL;
callbacks.tell_func = &tell_ogg;
ret = ov_open_callbacks (ec, &vf, NULL, 0, callbacks);
if (0 != ret)
{
ov_clear (&vf);
return;
}
comments = ov_comment (&vf, -1);
if (NULL == comments)
{
ov_clear (&vf);
return;
}
ADD (EXTRACTOR_METATYPE_MIMETYPE, "application/ogg");
if ((comments->vendor != NULL) && (strlen (comments->vendor) > 0))
ADD (EXTRACTOR_METATYPE_VENDOR, comments->vendor);
ADDG (EXTRACTOR_METATYPE_TITLE, "title");
ADDG (EXTRACTOR_METATYPE_ARTIST, "artist");
ADDG (EXTRACTOR_METATYPE_PERFORMER, "performer");
ADDG (EXTRACTOR_METATYPE_ALBUM, "album");
ADDG (EXTRACTOR_METATYPE_TRACK_NUMBER, "tracknumber");
ADDG (EXTRACTOR_METATYPE_DISC_NUMBER, "discnumber");
ADDG (EXTRACTOR_METATYPE_CONTACT_INFORMATION, "contact");
ADDG (EXTRACTOR_METATYPE_GENRE, "genre");
ADDG (EXTRACTOR_METATYPE_CREATION_DATE, "date");
ADDG (EXTRACTOR_METATYPE_COMMENT, "");
ADDG (EXTRACTOR_METATYPE_LOCATION_SUBLOCATION, "location");
ADDG (EXTRACTOR_METATYPE_DESCRIPTION, "description");
ADDG (EXTRACTOR_METATYPE_ISRC, "isrc");
ADDG (EXTRACTOR_METATYPE_ORGANIZATION, "organization");
ADDG (EXTRACTOR_METATYPE_COPYRIGHT, "copyright");
ADDG (EXTRACTOR_METATYPE_LICENSE, "license");
ADDG (EXTRACTOR_METATYPE_SONG_VERSION, "version");
FINISH:
ov_clear (&vf);
}
/* end of ogg_extractor.c */
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