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/*
This file is part of libextractor.
Copyright (C) 2002, 2003, 2004, 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/jpeg_extractor.c
* @brief plugin to support JPEG files
* @author Christian Grothoff
*/
#include "platform.h"
#include "extractor.h"
#if WINDOWS || DARWIN
#if DARWIN
typedef int boolean;
#endif
#define HAVE_BOOLEAN
#endif
#include <jpeglib.h>
#include <setjmp.h>
/**
* Context for custom functions.
*/
struct Context
{
/**
* Environment for longjmp from within error_exit handler.
*/
jmp_buf env;
};
/**
* Function used to avoid having libjpeg write error messages to the console.
*/
static void
no_emit (j_common_ptr cinfo, int msg_level)
{
/* do nothing */
}
/**
* Function used to avoid having libjpeg write error messages to the console.
*/
static void
no_output (j_common_ptr cinfo)
{
/* do nothing */
}
/**
* Function used to avoid having libjpeg kill our process.
*/
static void
no_exit (j_common_ptr cinfo)
{
struct Context *ctx = cinfo->client_data;
/* we're not allowed to return (by API definition),
and we don't want to abort/exit. So we longjmp
to our cleanup code instead. */
longjmp (ctx->env, 1);
}
/**
* Main entry method for the 'image/jpeg' extraction plugin.
*
* @param ec extraction context provided to the plugin
*/
void
EXTRACTOR_jpeg_extract_method (struct EXTRACTOR_ExtractContext *ec)
{
struct jpeg_decompress_struct jds;
struct jpeg_error_mgr em;
void *buf;
ssize_t size;
int is_jpeg;
unsigned int rounds;
char format[128];
struct jpeg_marker_struct *mptr;
struct Context ctx;
is_jpeg = 0;
rounds = 0; /* used to avoid going on forever for non-jpeg files */
jpeg_std_error (&em);
em.emit_message = &no_emit;
em.output_message = &no_output;
em.error_exit = &no_exit;
jds.client_data = &ctx;
if (1 == setjmp (ctx.env))
goto EXIT; /* we get here if libjpeg calls 'no_exit' because it wants to die */
jds.err = &em;
jpeg_create_decompress (&jds);
jpeg_save_markers (&jds, JPEG_COM, 1024 * 8);
while ( (1 == is_jpeg) || (rounds++ < 8) )
{
if (-1 == (size = ec->read (ec->cls,
&buf,
16 * 1024)))
break;
if (0 == size)
break;
jpeg_mem_src (&jds, buf, size);
if (0 == is_jpeg)
{
if (JPEG_HEADER_OK == jpeg_read_header (&jds, 1))
is_jpeg = 1; /* ok, really a jpeg, keep going until the end */
continue;
}
jpeg_consume_input (&jds);
}
if (1 != is_jpeg)
goto EXIT;
if (0 !=
ec->proc (ec->cls,
"jpeg",
EXTRACTOR_METATYPE_MIMETYPE,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
"image/jpeg",
strlen ("image/jpeg") + 1))
goto EXIT;
snprintf (format,
sizeof (format),
"%ux%u",
(unsigned int) jds.image_width,
(unsigned int) jds.image_height);
if (0 !=
ec->proc (ec->cls,
"jpeg",
EXTRACTOR_METATYPE_IMAGE_DIMENSIONS,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
format,
strlen (format) + 1))
goto EXIT;
for (mptr = jds.marker_list; NULL != mptr; mptr = mptr->next)
{
size_t off;
if (JPEG_COM != mptr->marker)
continue;
off = 0;
while ( (off < mptr->data_length) &&
(isspace (((const unsigned char *) mptr->data)[mptr->data_length
- 1 - off])) )
off++;
if (0 !=
ec->proc (ec->cls,
"jpeg",
EXTRACTOR_METATYPE_COMMENT,
EXTRACTOR_METAFORMAT_C_STRING,
"text/plain",
(const char *) mptr->data,
mptr->data_length - off))
goto EXIT;
}
EXIT:
jpeg_destroy_decompress (&jds);
}
/* end of jpeg_extractor.c */
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