mirror of
https://git.code.sf.net/p/libpng/code.git
synced 2025-07-10 18:04:09 +02:00
0c7ac064d3
For inflate, reverted previous fixes. Added fixitxt and pngdeflate to the built programs and removed warnings from the source code and timepng that are revealed as a result. Fixed fixitxt when the chunk length is more than 65535 (untested, no test case).
148 lines
3.5 KiB
C
148 lines
3.5 KiB
C
#include <stdio.h>
|
|
|
|
/* fixitxt version 1.0.0
|
|
*
|
|
* Copyright 2013 Glenn Randers-Pehrson
|
|
*
|
|
* This code is released under the libpng license.
|
|
* For conditions of distribution and use, see the disclaimer
|
|
* and license in png.h
|
|
*
|
|
* Usage:
|
|
*
|
|
* fixitxt.exe < bad.png > good.png
|
|
*
|
|
* Fixes a PNG file written with libpng-1.6.0 or 1.6.1 that has one or more
|
|
* uncompressed iTXt chunks. Assumes that the actual length is greater
|
|
* than or equal to the value in the length byte, and that the CRC is
|
|
* correct for the actual length. This program hunts for the CRC and
|
|
* adjusts the length byte accordingly. It is not an error to process a
|
|
* PNG file that has no iTXt chunks or one that has valid iTXt chunks;
|
|
* such files will simply be copied.
|
|
*
|
|
* Requires zlib (for crc32 and Z_NULL); build with
|
|
*
|
|
* gcc -O -o fixitxt fixitxt.c -lz
|
|
*/
|
|
#include <zlib.h>
|
|
|
|
#define MAX_LENGTH 500000
|
|
|
|
#define GETBREAK ((unsigned char)(inchar=getchar())); if (inchar == EOF) break
|
|
|
|
int
|
|
main(void)
|
|
{
|
|
unsigned int i;
|
|
unsigned char buf[MAX_LENGTH];
|
|
unsigned long crc;
|
|
unsigned char c;
|
|
int inchar;
|
|
|
|
/* Skip 8-byte signature */
|
|
for (i=8; i; i--)
|
|
{
|
|
c=GETBREAK;
|
|
putchar(c);
|
|
}
|
|
|
|
if (inchar != EOF)
|
|
for (;;)
|
|
{
|
|
/* Read the length */
|
|
unsigned long length; /* must be 32 bits! */
|
|
c=GETBREAK; buf[0] = c; length = c; length <<= 8;
|
|
c=GETBREAK; buf[1] = c; length += c; length <<= 8;
|
|
c=GETBREAK; buf[2] = c; length += c; length <<= 8;
|
|
c=GETBREAK; buf[3] = c; length += c;
|
|
|
|
/* Read the chunkname */
|
|
c=GETBREAK; buf[4] = c;
|
|
c=GETBREAK; buf[5] = c;
|
|
c=GETBREAK; buf[6] = c;
|
|
c=GETBREAK; buf[7] = c;
|
|
|
|
|
|
/* The iTXt chunk type expressed as integers is (105, 84, 88, 116) */
|
|
if (buf[4] == 105 && buf[5] == 84 && buf[6] == 88 && buf[7] == 116)
|
|
{
|
|
if (length >= MAX_LENGTH-12)
|
|
break; /* To do: handle this more gracefully */
|
|
|
|
/* Initialize the CRC */
|
|
crc = crc32(0, Z_NULL, 0);
|
|
|
|
/* Copy the data bytes */
|
|
for (i=8; i < length + 12; i++)
|
|
{
|
|
c=GETBREAK; buf[i] = c;
|
|
}
|
|
|
|
/* Calculate the CRC */
|
|
crc = crc32(crc, buf+4, (uInt)length+4);
|
|
|
|
for (;;)
|
|
{
|
|
/* Check the CRC */
|
|
if (((crc >> 24) & 0xff) == buf[length+8] &&
|
|
((crc >> 16) & 0xff) == buf[length+9] &&
|
|
((crc >> 8) & 0xff) == buf[length+10] &&
|
|
((crc ) & 0xff) == buf[length+11])
|
|
break;
|
|
|
|
length++;
|
|
|
|
if (length >= MAX_LENGTH-12)
|
|
break;
|
|
|
|
c=GETBREAK;
|
|
buf[length+11]=c;
|
|
|
|
/* Update the CRC */
|
|
crc = crc32(crc, buf+7+length, 1);
|
|
}
|
|
|
|
/* Update length bytes */
|
|
buf[0] = (length << 24) & 0xff;
|
|
buf[1] = (length << 16) & 0xff;
|
|
buf[2] = (length << 8) & 0xff;
|
|
buf[3] = (length ) & 0xff;
|
|
|
|
/* Write the fixed iTXt chunk (length, name, data, crc) */
|
|
for (i=0; i<length+12; i++)
|
|
putchar(buf[i]);
|
|
}
|
|
|
|
else
|
|
{
|
|
/* Copy bytes that were already read (length and chunk name) */
|
|
for (i=0; i<8; i++)
|
|
putchar(buf[i]);
|
|
|
|
/* Copy data bytes and CRC */
|
|
for (i=8; i< length+12; i++)
|
|
{
|
|
c=GETBREAK;
|
|
putchar(c);
|
|
}
|
|
|
|
if (inchar == EOF)
|
|
{
|
|
break;
|
|
}
|
|
|
|
/* The IEND chunk type expressed as integers is (73, 69, 78, 68) */
|
|
if (buf[4] == 73 && buf[5] == 69 && buf[6] == 78 && buf[7] == 68)
|
|
break;
|
|
}
|
|
|
|
if (inchar == EOF)
|
|
break;
|
|
|
|
if (buf[4] == 73 && buf[5] == 69 && buf[6] == 78 && buf[7] == 68)
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|