pcompress/archive/pjpg_helper.cpp

107 lines
2.8 KiB
C++
Raw Normal View History

/*
* This file is a part of Pcompress, a chunked parallel multi-
* algorithm lossless compression and decompression program.
*
2013-03-07 14:56:48 +00:00
* Copyright (C) 2012-2013 Moinak Ghosh. All rights reserved.
* Use is subject to license terms.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 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
* Lesser General Public License for more details.
*
2013-03-07 14:56:48 +00:00
* You should have received a copy of the GNU Lesser General Public
* License along with this program.
* If not, see <http://www.gnu.org/licenses/>.
*
* moinakg@belenix.org, http://moinakg.wordpress.com/
*
*/
/*
*/
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <utils.h>
#include <packjpglib.h>
#ifdef __cplusplus
extern "C" {
#endif
typedef unsigned char uchar_t;
/* a short reminder about input/output stream types
for the pjglib_init_streams() function
if input is file
----------------
in_scr -> name of input file
in_type -> 0
in_size -> ignore
if input is memory
------------------
in_scr -> array containg data
in_type -> 1
in_size -> size of data array
if input is *FILE (f.e. stdin)
------------------------------
in_src -> stream pointer
in_type -> 2
in_size -> ignore
vice versa for output streams! */
#define POLAROID_LE 0x64696f72616c6f50
/*
* Helper routine to bridge to packJPG C++ lib, without changing packJPG itself.
*/
size_t
packjpg_filter_process(uchar_t *in_buf, size_t len, uchar_t **out_buf)
{
unsigned int len1;
uchar_t *pos;
/*
* Workaround for packJPG limitation, not a bug per se. Images created with
* Polaroid cameras appear to have some weird huffman data in the middle which
* appears not to be interpreted by any image viewer/editor. This data gets
* stripped by packJPG.
* So the restored images will be visually correct, but, will be smaller than the
* original. So we need to look at the Exif Manufacturer tag for 'Polaroid' and
* skip those images. This should be within the first 512 bytes of the
* file (really...?) so we do a simple buffer scan without trying to parse Exif
* data.
*/
pos = (uchar_t *)memchr(in_buf, 'P', 512);
while (pos) {
if (LE64(U64_P(pos)) == POLAROID_LE)
return (0);
pos++;
pos = (uchar_t *)memchr(pos, 'P', 512);
}
pjglib_init_streams(in_buf, 1, len, *out_buf, 1);
len1 = len;
if (!pjglib_convert_stream2mem(out_buf, &len1, NULL))
return (0);
if (len1 == len)
return (0);
return (len1);
}
#ifdef __cplusplus
}
#endif