convert mode 2 cdrom image files (iso) to mode 1 format

mode2.c

#include <stdio.h>
#include <string.h>

/* small program to convert mode 2 form 1 (XA) cdrom iso files, as produced
   by some windows software - maybe nero - to regular mode 1 iso file format.
   because for some reason, linux can only mount mode 1 iso files.
   the format encountered is basically a raw dump of the disc, including
   checksum bytes, sync markers and header.
   the means that the \1CD001 header starts at offset 0x9318 instead of 0x8000.

   the necessary information was gathered on
   http://www.icdia.co.uk/faq/cdifaq3.html and
   https://forums.virtualbox.org/viewtopic.php?t=102163

   in order to write form 2 disk, define MODE2_FORM2 before compiling.
*/

#ifdef MODE2_FORM2
#define OUTBYTES 2324
#else
#define OUTBYTES 2048
#endif

int main() {
	unsigned char buf[12+4+8+2048+280];
	while(1) {
		size_t l = fread(buf, sizeof(buf), 1, stdin);
		if(!l) return 0;
		if(memcmp("\0\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\0", buf, 12))
		{
			fprintf(stderr, "err: no sync bytes found!\n");
			return 1;
		}
		if(buf[15] != '\002') {
			fprintf(stderr, "err: not mode2!\n");
			return 1;
		}
		fwrite(buf+24, OUTBYTES, 1, stdout);
	}
}