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/*- iccfrompng
*
* COPYRIGHT: Written by John Cunningham Bowler, 2011.
* To the extent possible under law, the author has waived all copyright and
* related or neighboring rights to this work. This work is published from:
* United States.
*
* Extract any icc profiles found in the given PNG files. This is a simple
* example of a program that extracts information from the header of a PNG file
* without processing the image. Notice that some header information may occur
* after the image data. Textual data and comments are an example; the approach
* in this file won't work reliably for such data because it only looks for the
* information in the section of the file that preceeds the image data.
*
* Compile and link against libpng and zlib, plus anything else required on the
* system you use.
*
* To use supply a list of PNG files containing iCCP chunks, the chunks will be
* extracted to a similarly named file with the extension replaced by 'icc',
* which will be overwritten without warning.
*/
#include <stdlib.h>
#include <setjmp.h>
#include <string.h>
#include <stdio.h>
#include <png.h>
static int verbose = 1;
static png_byte no_profile[] = "no profile";
static png_bytep
extract(FILE *fp, png_uint_32 *proflen)
{
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
png_infop info_ptr = NULL;
png_bytep result = NULL;
/* Initialize for error or no profile: */
*proflen = 0;
if (png_ptr == NULL)
{
fprintf(stderr, "iccfrompng: version library mismatch?\n");
return 0;
}
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
return 0;
}
png_init_io(png_ptr, fp);
info_ptr = png_create_info_struct(png_ptr);
if (info_ptr == NULL)
png_error(png_ptr, "OOM allocating info structure");
png_read_info(png_ptr, info_ptr);
{
png_charp name;
int compression_type;
png_bytep profile;
if (png_get_iCCP(png_ptr, info_ptr, &name, &compression_type, &profile,
proflen) & PNG_INFO_iCCP)
{
result = malloc(*proflen);
if (result != NULL)
memcpy(result, profile, *proflen);
else
png_error(png_ptr, "OOM allocating profile buffer");
}
else
result = no_profile;
}
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
return result;
}
static int
extract_one_file(const char *filename)
{
int result = 0;
FILE *fp = fopen(filename, "rb");
if (fp != NULL)
{
png_uint_32 proflen = 0;
png_bytep profile = extract(fp, &proflen);
if (profile != NULL && profile != no_profile)
{
size_t len;
char *output;
{
const char *ep = strrchr(filename, '.');
if (ep != NULL)
len = ep-filename;
else
len = strlen(filename);
}
output = malloc(len + 5);
if (output != NULL)
{
FILE *of;
memcpy(output, filename, len);
strcpy(output+len, ".icc");
of = fopen(output, "wb");
if (of != NULL)
{
if (fwrite(profile, proflen, 1, of) == 1 &&
fflush(of) == 0 &&
fclose(of) == 0)
{
if (verbose)
printf("%s -> %s\n", filename, output);
/* Success return */
result = 1;
}
else
{
fprintf(stderr, "%s: error writing profile\n", output);
if (remove(output))
fprintf(stderr, "%s: could not remove file\n", output);
}
}
else
fprintf(stderr, "%s: failed to open output file\n", output);
free(output);
}
else
fprintf(stderr, "%s: OOM allocating string!\n", filename);
free(profile);
}
else if (verbose && profile == no_profile)
printf("%s has no profile\n", filename);
}
else
fprintf(stderr, "%s: could not open file\n", filename);
return result;
}
int
main(int argc, char **argv)
{
int i;
int extracted = 0;
for (i=1; i<argc; ++i)
{
if (strcmp(argv[i], "-q") == 0)
verbose = 0;
else if (extract_one_file(argv[i]))
extracted = 1;
}
/* Exit code is true if any extract succeeds */
return extracted == 0;
}
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