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/*
This file is part of libextractor.
Copyright (C) 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/gif_extractor.c
* @brief plugin to support GIF files
* @author Christian Grothoff
*/
#include "platform.h"
#include "extractor.h"
#include <gif_lib.h>
/**
* Callback invoked by libgif to read data.
*
* @param ft the file handle, including our extract context
* @param bt where to write the data
* @param arg number of bytes to read
* @return -1 on error, otherwise number of bytes read
*/
static int
gif_read_func (GifFileType *ft,
GifByteType *bt,
int arg)
{
struct EXTRACTOR_ExtractContext *ec = ft->UserData;
void *data;
ssize_t ret;
ret = ec->read (ec->cls,
&data,
arg);
if (-1 == ret)
return -1;
memcpy (bt, data, ret);
return ret;
}
/**
* Main entry method for the 'image/gif' extraction plugin.
*
* @param ec extraction context provided to the plugin
*/
void
EXTRACTOR_gif_extract_method (struct EXTRACTOR_ExtractContext *ec)
{
GifFileType *gif_file;
GifRecordType gif_type;
GifByteType *ext;
int et;
char dims[128];
#if defined (GIF_LIB_VERSION) || GIFLIB_MAJOR <= 4
if (NULL == (gif_file = DGifOpen (ec, &gif_read_func)))
return; /* not a GIF */
#else
int gif_error;
gif_error = 0;
gif_file = DGifOpen (ec, &gif_read_func, &gif_error);
if (gif_file == NULL || gif_error != 0)
{
if (gif_file != NULL)
#if GIFLIB_MAJOR < 5 || GIFLIB_MINOR < 1
EGifCloseFile (gif_file);
#else
EGifCloseFile (gif_file, NULL);
#endif
return; /* not a GIF */
}
#endif
if (0 !=
ec->proc (ec->cls,
"gif",
EXTRACTOR_METATYPE_MIMETYPE,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
"image/gif",
strlen ("image/gif") + 1))
return;
snprintf (dims,
sizeof (dims),
"%dx%d",
gif_file->SHeight,
gif_file->SWidth);
if (0 !=
ec->proc (ec->cls,
"gif",
EXTRACTOR_METATYPE_IMAGE_DIMENSIONS,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
dims,
strlen (dims) + 1))
return;
while (1)
{
if (GIF_OK !=
DGifGetRecordType (gif_file,
&gif_type))
break;
if (UNDEFINED_RECORD_TYPE == gif_type)
break;
if (EXTENSION_RECORD_TYPE != gif_type)
continue;
if (GIF_OK !=
DGifGetExtension (gif_file, &et, &ext))
continue;
if (NULL == ext)
continue;
if (COMMENT_EXT_FUNC_CODE == et)
{
ec->proc (ec->cls,
"gif",
EXTRACTOR_METATYPE_COMMENT,
EXTRACTOR_METAFORMAT_C_STRING,
"text/plain",
(char*) &ext[1],
(uint8_t) ext[0]);
break;
}
while ( (GIF_ERROR !=
DGifGetExtensionNext(gif_file, &ext)) &&
(NULL != ext) ) ; /* keep going */
}
#if defined (GIF_LIB_VERSION) || GIFLIB_MAJOR < 5 || GIFLIB_MINOR < 1
DGifCloseFile (gif_file);
#else
DGifCloseFile (gif_file, NULL);
#endif
}
/* end of gif_extractor.c */
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