#include <stdio.h>
#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>

#include <inttypes.h>

#include <err.h>

#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>

int main(int argc, char **argv)
{
	int fd;
	struct stat sb;
	void *p;
	uint8_t *hdr;
	int setup_sectors;
	uint32_t compressed_payload_offset;
	uint32_t compressed_payload_length;

	if (argc != 2)
		errx(1, "usage: bzexplode <bzImage>");

	fd = open(argv[1], O_RDONLY);
	if (fd < 0)
		err(1, "open");

	if (fstat(fd, &sb) < 0)
		err(1, "fstat");

	p = mmap(0, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
	if (p == MAP_FAILED)
		err(1, "mmap");

	hdr = p;
	setup_sectors = hdr[0x1f1];
	compressed_payload_offset = *(uint32_t*)&hdr[0x248];

	fprintf(stderr, "setup sectors %d\n", setup_sectors);

	compressed_payload_offset += (setup_sectors+1) * 512;

	//compressed_payload_length = *(uint32_t*)(p + compressed_payload_offset - 4);
	compressed_payload_length = *(uint32_t*)&hdr[0x24c];

	fprintf(stderr, "compressed_payload_offset %"PRIx32" (abs)\n",
		compressed_payload_offset);
	fprintf(stderr, "compressed_payload_length %"PRIx32"\n",
		compressed_payload_length);

	write(1,
	      p + compressed_payload_offset,
	      compressed_payload_length);
	return 0;
}