const char deanimate_rcs[] = "$Id: deanimate.c,v 1.19 2008/05/21 15:29:35 fabiankeil Exp $";
/*********************************************************************
*
* File : $Source: /cvsroot/ijbswa/current/deanimate.c,v $
*
* Purpose : Declares functions to manipulate binary images on the
* fly. High-level functions include:
* - Deanimation of GIF images
*
* Functions declared include: gif_deanimate, buf_free,
* buf_copy, buf_getbyte, gif_skip_data_block
* and gif_extract_image
*
* Copyright : Written by and Copyright (C) 2001 - 2004, 2006 by the
* SourceForge Privoxy team. http://www.privoxy.org/
*
* Based on the GIF file format specification (see
* http://tronche.com/computer-graphics/gif/gif89a.html)
* and ideas from the Image::DeAnim Perl module by
* Ken MacFarlane, <ksm+cpan@universal.dca.net>
*
* This program 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 of the License, or (at
* your option) any later version.
*
* This program 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.
*
* The GNU General Public License should be included with
* this file. If not, you can view it at
* http://www.gnu.org/copyleft/gpl.html
* or write to the Free Software Foundation, Inc., 59
* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Revisions :
* $Log: deanimate.c,v $
* Revision 1.19 2008/05/21 15:29:35 fabiankeil
* Fix gcc43 warnings.
*
* Revision 1.18 2008/03/28 15:13:38 fabiankeil
* Remove inspect-jpegs action.
*
* Revision 1.17 2007/08/05 13:42:22 fabiankeil
* #1763173 from Stefan Huehner: declare some more functions static.
*
* Revision 1.16 2007/07/14 08:01:58 fabiankeil
* s@failiure@failure@
*
* Revision 1.15 2007/01/03 14:39:19 fabiankeil
* Fix a gcc43 warning and mark the binbuffer
* as immutable for buf_getbyte().
*
* Revision 1.14 2006/07/18 14:48:45 david__schmidt
* Reorganizing the repository: swapping out what was HEAD (the old 3.1 branch)
* with what was really the latest development (the v_3_0_branch branch)
*
* Revision 1.12.2.1 2004/10/03 12:53:32 david__schmidt
* Add the ability to check jpeg images for invalid
* lengths of comment blocks. Defensive strategy
* against the exploit:
* Microsoft Security Bulletin MS04-028
* Buffer Overrun in JPEG Processing (GDI+) Could
* Allow Code Execution (833987)
* Enabled with +inspect-jpegs in actions files.
*
* Revision 1.12 2002/05/12 21:36:29 jongfoster
* Correcting function comments
*
* Revision 1.11 2002/03/26 22:29:54 swa
* we have a new homepage!
*
* Revision 1.10 2002/03/24 13:25:43 swa
* name change related issues
*
* Revision 1.9 2002/03/13 00:27:04 jongfoster
* Killing warnings
*
* Revision 1.8 2002/03/09 19:42:47 jongfoster
* Fixing more warnings
*
* Revision 1.7 2002/03/08 17:46:04 jongfoster
* Fixing int/size_t warnings
*
* Revision 1.6 2002/03/07 03:46:17 oes
* Fixed compiler warnings
*
* Revision 1.5 2001/09/10 10:16:06 oes
* Silenced compiler warnings
*
* Revision 1.4 2001/07/18 12:28:49 oes
* - Added feature for extracting the first frame
* to gif_deanimate
* - Separated image buffer extension into buf_extend
* - Extended gif deanimation to GIF87a (untested!)
* - Cosmetics
*
* Revision 1.3 2001/07/15 13:57:50 jongfoster
* Adding #includes string.h and miscutil.h
*
* Revision 1.2 2001/07/13 13:46:20 oes
* Introduced GIF deanimation feature
*
*
**********************************************************************/
#include "config.h"
#include <string.h>
#include <fcntl.h>
#include "errlog.h"
#include "project.h"
#include "deanimate.h"
#include "miscutil.h"
const char deanimate_h_rcs[] = DEANIMATE_H_VERSION;
/*********************************************************************
*
* Function : buf_free
*
* Description : Safely frees a struct binbuffer
*
* Parameters :
* 1 : buf = Pointer to the binbuffer to be freed
*
* Returns : N/A
*
*********************************************************************/
void buf_free(struct binbuffer *buf)
{
if (buf == NULL) return;
if (buf->buffer != NULL)
{
free(buf->buffer);
}
free(buf);
}
/*********************************************************************
*
* Function : buf_extend
*
* Description : Ensure that a given binbuffer can hold a given amount
* of bytes, by reallocating its buffer if necessary.
* Allocate new mem in chunks of 1024 bytes, so we don't
* have to realloc() too often.
*
* Parameters :
* 1 : buf = Pointer to the binbuffer
* 2 : length = Desired minimum size
*
*
* Returns : 0 on success, 1 on failure.
*
*********************************************************************/
static int buf_extend(struct binbuffer *buf, size_t length)
{
char *newbuf;
if (buf->offset + length > buf->size)
{
buf->size = ((buf->size + length + (size_t)1023) & ~(size_t)1023);
newbuf = (char *)realloc(buf->buffer, buf->size);
if (newbuf == NULL)
{
freez(buf->buffer);
return 1;
}
else
{
buf->buffer = newbuf;
return 0;
}
}
return 0;
}
/*********************************************************************
*
* Function : buf_copy
*
* Description : Safely copies a given amount of bytes from one
* struct binbuffer to another, advancing the
* offsets appropriately.
*
* Parameters :
* 1 : src = Pointer to the source binbuffer
* 2 : dst = Pointer to the destination binbuffer
* 3 : length = Number of bytes to be copied
*
* Returns : 0 on success, 1 on failure.
*
*********************************************************************/
static int buf_copy(struct binbuffer *src, struct binbuffer *dst, size_t length)
{
/*
* Sanity check: Can't copy more data than we have
*/
if (src->offset + length > src->size)
{
return 1;
}
/*
* Ensure that dst can hold the new data
*/
if (buf_extend(dst, length))
{
return 1;
}
/*
* Now that it's safe, memcpy() the desired amount of
* data from src to dst and adjust the offsets
*/
memcpy(dst->buffer + dst->offset, src->buffer + src->offset, length);
src->offset += length;
dst->offset += length;
return 0;
}
/*********************************************************************
*
* Function : buf_getbyte
*
* Description : Safely gets a byte from a given binbuffer at a
* given offset
*
* Parameters :
* 1 : src = Pointer to the source binbuffer
* 2 : offset = Offset to the desired byte
*
* Returns : The byte on success, or 0 on failure
*
*********************************************************************/
static unsigned char buf_getbyte(const struct binbuffer *src, size_t offset)
{
if (src->offset + offset < src->size)
{
return (unsigned char)*(src->buffer + src->offset + offset);
}
else
{
return '\0';
}
}
/*********************************************************************
*
* Function : gif_skip_data_block
*
* Description : Safely advances the offset of a given struct binbuffer
* that contains a GIF image and whose offset is
* positioned at the start of a data block, behind
* that block.
*
* Parameters :
* 1 : buf = Pointer to the binbuffer
*
* Returns : 0 on success, or 1 on failure
*
*********************************************************************/
static int gif_skip_data_block(struct binbuffer *buf)
{
unsigned char c;
/*
* Data blocks are sequences of chunks, which are headed
* by a one-byte length field, with the last chunk having
* zero length.
*/
while((c = buf_getbyte(buf, 0)) != '\0')
{
buf->offset += (size_t)c + 1;
if (buf->offset >= buf->size - 1)
{
return 1;
}
}
buf->offset++;
return 0;
}
/*********************************************************************
*
* Function : gif_extract_image
*
* Description : Safely extracts an image data block from a given
* struct binbuffer that contains a GIF image and whose
* offset is positioned at the start of a data block
* into a given destination binbuffer.
*
* Parameters :
* 1 : src = Pointer to the source binbuffer
* 2 : dst = Pointer to the destination binbuffer
*
* Returns : 0 on success, or 1 on failure
*
*********************************************************************/
static int gif_extract_image(struct binbuffer *src, struct binbuffer *dst)
{
unsigned char c;
/*
* Remember the colormap flag and copy the image head
*/
c = buf_getbyte(src, 9);
if (buf_copy(src, dst, 10))
{
return 1;
}
/*
* If the image has a local colormap, copy it.
*/
if (c & 0x80)
{
int map_length = 3 * (1 << ((c & 0x07) + 1));
if (map_length <= 0)
{
log_error(LOG_LEVEL_DEANIMATE,
"colormap length = %d (%c)?", map_length, c);
return 1;
}
if (buf_copy(src, dst, (size_t)map_length))
{
return 1;
}
}
if (buf_copy(src, dst, 1)) return 1;
/*
* Copy the image chunk by chunk.
*/
while((c = buf_getbyte(src, 0)) != '\0')
{
if (buf_copy(src, dst, 1 + (size_t) c)) return 1;
}
if (buf_copy(src, dst, 1)) return 1;
/*
* Trim and rewind the dst buffer
*/
if (NULL == (dst->buffer = (char *)realloc(dst->buffer, dst->offset))) return 1;
dst->size = dst->offset;
dst->offset = 0;
return(0);
}
/*********************************************************************
*
* Function : gif_deanimate
*
* Description : Deanimate a given GIF image, i.e. given a GIF with
* an (optional) image block and an arbitrary number
* of image extension blocks, produce an output GIF with
* only one image block that contains the last image
* (extenstion) block of the original.
* Also strip Comments, Application extenstions, etc.
*
* Parameters :
* 1 : src = Pointer to the source binbuffer
* 2 : dst = Pointer to the destination binbuffer
* 3 : get_first_image = Flag: If set, get the first image
* If unset (default), get the last
*
* Returns : 0 on success, or 1 on failure
*
*********************************************************************/
int gif_deanimate(struct binbuffer *src, struct binbuffer *dst, int get_first_image)
{
unsigned char c;
struct binbuffer *image;
if (NULL == src || NULL == dst)
{
return 1;
}
c = buf_getbyte(src, 10);
/*
* Check & copy GIF header
*/
if (strncmp(src->buffer, "GIF89a", 6) && strncmp(src->buffer, "GIF87a", 6))
{
return 1;
}
else
{
if (buf_copy(src, dst, 13))
{
return 1;
}
}
/*
* Look for global colormap and copy if found.
*/
if(c & 0x80)
{
int map_length = 3 * (1 << ((c & 0x07) + 1));
if (map_length <= 0)
{
log_error(LOG_LEVEL_DEANIMATE,
"colormap length = %d (%c)?", map_length, c);
return 1;
}
if (buf_copy(src, dst, (size_t)map_length))
{
return 1;
}
}
/*
* Reserve a buffer for the current image block
*/
if (NULL == (image = (struct binbuffer *)zalloc(sizeof(*image))))
{
return 1;
}
/*
* Parse the GIF block by block and copy the relevant
* parts to dst
*/
while(src->offset < src->size)
{
switch(buf_getbyte(src, 0))
{
/*
* End-of-GIF Marker: Append current image and return
*/
case 0x3b:
goto write;
/*
* Image block: Extract to current image buffer.
*/
case 0x2c:
image->offset = 0;
if (gif_extract_image(src, image)) goto failed;
if (get_first_image) goto write;
continue;
/*
* Extension block: Look at next byte and decide
*/
case 0x21:
switch (buf_getbyte(src, 1))
{
/*
* Image extension: Copy extension header and image
* to the current image buffer
*/
case 0xf9:
image->offset = 0;
if (buf_copy(src, image, 8) || buf_getbyte(src, 0) != 0x2c) goto failed;
if (gif_extract_image(src, image)) goto failed;
if (get_first_image) goto write;
continue;
/*
* Application extension: Skip
*/
case 0xff:
if ((src->offset += 14) >= src->size || gif_skip_data_block(src)) goto failed;
continue;
/*
* Comment extension: Skip
*/
case 0xfe:
if ((src->offset += 2) >= src->size || gif_skip_data_block(src)) goto failed;
continue;
/*
* Plain text extension: Skip
*/
case 0x01:
if ((src->offset += 15) >= src->size || gif_skip_data_block(src)) goto failed;
continue;
/*
* Ooops, what type of extension is that?
*/
default:
goto failed;
}
/*
* Ooops, what type of block is that?
*/
default:
goto failed;
}
} /* -END- while src */
/*
* Either we got here by goto, or because the GIF is
* bogus and EOF was reached before an end-of-gif marker
* was found.
*/
failed:
buf_free(image);
return 1;
/*
* Append the current image to dst and return
*/
write:
if (buf_copy(image, dst, image->size)) goto failed;
if (buf_extend(dst, 1)) goto failed;
*(dst->buffer + dst->offset++) = 0x3b;
buf_free(image);
return 0;
}
/*
Local Variables:
tab-width: 3
end:
*/