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Added CgBI chunk detection

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Apple's xcode SDK for iPhone inserts a CgBI chunk ahead of IHDR.  There are
other changes that make the file unreadable by libpng so we detect
the chunk, list the remaining chunks, and abandon the file.
This commit is contained in:
Glenn Randers-Pehrson glennrp@comcast.net
2009-04-29 07:54:01 -05:00
parent 00bd2d9786
commit 1b9aa7c882
1 changed files with 86 additions and 28 deletions
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114
pngcrush.c
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@@ -184,6 +184,14 @@
((png_uint_32) 68 ))
#endif
/* glennrp added CgBI at pngcrush-1.6.16 */
#ifndef PNG_UINT_CgBI
# define PNG_UINT_CgBI (((png_uint_32) 67<<24) | \
((png_uint_32) 103<<16) | \
((png_uint_32) 66<< 8) | \
((png_uint_32) 73 ))
#endif
#ifndef PNG_UINT_cHRM
# define PNG_UINT_cHRM (((png_uint_32) 99<<24) | \
((png_uint_32) 72<<16) | \
@@ -454,6 +462,7 @@ static png_uint_32 width, height;
static png_uint_32 measured_idat_length;
static int found_gAMA = 0;
static int found_cHRM = 0;
static int found_CgBI = 0;
static int found_any_chunk = 0;
static int image_is_immutable = 0;
static int pngcrush_must_exit = 0;
@@ -1274,7 +1283,25 @@ void png_crush_pause(void)
}
void png_skip_chunk(png_structp png_ptr)
{
png_byte buff[4];
int i;
unsigned long length;
/* read the length field */
png_default_read_data(png_ptr, buff, 4);
length=buff[3]+(buff[2]<<8)+(buff[1]<<16)+(buff[0]<<24);
/* read the chunk name */
png_default_read_data(png_ptr, buff, 4);
printf("Skipping %c%c%c%c chunk.\n",buff[0],buff[1],
buff[2],buff[3]);
/* skip the data */
for (i=0; i<length; i++)
png_default_read_data(png_ptr, buff, 1);
/* skip the CRC */
png_default_read_data(png_ptr, buff, 4);
}
#ifndef __riscos
# define setfiletype(x)
@@ -2925,27 +2952,33 @@ int main(int argc, char *argv[])
#if defined(PNGCRUSH_LOCO)
if (!(int)
(png_memcmp(mng_signature, png_signature, 8))) {
png_byte buff[40];
unsigned long length;
/* Skip the MHDR */
png_permit_mng_features(read_ptr,
PNG_FLAG_MNG_FILTER_64);
png_default_read_data(read_ptr, buff, 4);
length=buff[3]+(buff[2]<<8)+(buff[1]<<16)+(buff[0]<<24);
png_default_read_data(read_ptr, buff, 4);
printf("Skipping %c%c%c%c chunk.\n",buff[0],buff[1],
buff[2],buff[3]);
png_default_read_data(read_ptr, buff, length);
png_default_read_data(read_ptr, buff, 4);
png_skip_chunk(read_ptr);
input_format = 1;
} else
#endif
if (png_sig_cmp(png_signature, 0, 8)) {
if (png_sig_cmp(png_signature, 0, 4))
png_error(read_ptr, "Not a PNG file!");
if (png_sig_cmp(png_signature, 0, 8)) {
if (png_sig_cmp(png_signature, 0, 4))
png_error(read_ptr, "Not a PNG file!");
else
png_error(read_ptr,
"PNG file corrupted by ASCII conversion");
"PNG file corrupted by ASCII conversion");
}
if(fix && found_CgBI)
{
#if 0 /* doesn't work */
printf("Handling CgBI chunk\n");
png_skip_chunk(read_ptr);
/* iCCP is probably bad */
png_set_keep_unknown_chunks(read_ptr,
PNG_HANDLE_CHUNK_NEVER,
(png_bytep)"iCCP", 1);
#else
png_error(read_ptr,
"Cannot read CgBI PNG.");
#endif
}
}
@@ -4848,7 +4881,6 @@ png_uint_32 png_measure_idat(png_structp png_ptr)
}
else {
#ifdef PNG_UINT_IDAT
if (png_get_uint_32(chunk_name) == PNG_UINT_IDAT)
#else
@@ -4865,6 +4897,20 @@ png_uint_32 png_measure_idat(png_structp png_ptr)
printf("Reading %s chunk, length = %lu.\n", chunk_name,
(unsigned long)length);
}
if (png_get_uint_32(chunk_name) == PNG_UINT_CgBI)
{
printf(" This is an Apple CGBI file, not a PNG file.\n");
if (fix)
{
printf (" Removing the CgBI chunk.\n");
} else {
printf (" Try \"pngcrush -fix ...\" to convert it to PNG.\n");
}
found_CgBI++;
}
#ifdef PNG_UINT_IHDR
if (png_get_uint_32(chunk_name) == PNG_UINT_IHDR)
#else
@@ -4934,7 +4980,6 @@ png_uint_32 png_measure_idat(png_structp png_ptr)
}
#endif
}
png_crc_finish(png_ptr, length);
@@ -4960,11 +5005,15 @@ png_uint_32 png_measure_idat(png_structp png_ptr)
if (input_format == 0) {
#ifdef PNG_UINT_IEND
if (png_get_uint_32(chunk_name) == PNG_UINT_IEND)
if (png_get_uint_32(chunk_name) == PNG_UINT_IEND) {
#else
if (!png_memcmp(chunk_name, png_IEND, 4))
if (!png_memcmp(chunk_name, png_IEND, 4)) {
#endif
return sum_idat_length;
if (!fix && found_CgBI)
return 0;
else
return sum_idat_length;
}
}
}
}
@@ -5070,15 +5119,8 @@ int count_colors(FILE * fp_in)
if (!(int) (png_memcmp(mng_signature, png_signature, 8))) {
png_byte buffer[40];
unsigned long length;
/* skip the MHDR */
png_default_read_data(read_ptr, buffer, 4);
length=buffer[3]+(buffer[2]<<8)+(buffer[1]<<16)
+(buffer[0]<<24);
png_default_read_data(read_ptr, buffer, 4);
printf("Skipping %c%c%c%c chunk.\n",buffer[0],buffer[1],
buffer[2],buffer[3]);
png_default_read_data(read_ptr, buffer, length);
png_default_read_data(read_ptr, buffer, 4);
/* Skip the MHDR chunk. */
png_skip_chunk(read_ptr);
png_permit_mng_features(read_ptr,
PNG_FLAG_MNG_FILTER_64);
input_format = 1;
@@ -5089,9 +5131,25 @@ int count_colors(FILE * fp_in)
png_error(read_ptr, "Not a PNG file.");
else
png_error(read_ptr,
"PNG file corrupted by ASCII conversion");
"PNG file corrupted by ASCII conversion");
}
}
printf("Handling CgBI chunk\n");
if (fix && found_CgBI){
#if 0 /* doesn't work */
/* Skip the CgBI chunk. */
png_skip_chunk(read_ptr);
/* iCCP is probably bad */
png_set_keep_unknown_chunks(read_ptr,
PNG_HANDLE_CHUNK_NEVER,
(png_bytep)"iCCP", 1);
#else
png_error(read_ptr,
"Cannot read CgBI PNG.");
#endif
}
png_read_info(read_ptr, read_info_ptr);
#ifdef PNG_CRC_QUIET_USE