#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>

#define min(x,y) (x<y?x:y)

int main(int argc, char **argv)
{
	int fd;
	off_t payload_offset = 0;
	struct stat sb;
	unsigned int len;
	off_t offset;
	int rc;
	char buf[4096];

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

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

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

	offset = lseek(fd, -8, SEEK_END);
	rc = read(fd, &payload_offset, 4);
	rc = read(fd, &len, 4);
	fprintf(stderr, "payload is at offset %zx = %zx\n",
		payload_offset, sb.st_size - payload_offset);
	fprintf(stderr, "payload len is %x\n", len);

	offset = lseek(fd, -payload_offset, SEEK_END);
	fprintf(stderr, "starting from %"PRIx64"\n", offset);

	while(len) {
		rc = read(fd, buf, min(len,sizeof(buf)));
		fprintf(stderr, "\rremaining %x %d", len, rc);
		write(1, buf, rc);
		len -= rc;
	}
	fprintf(stderr, "\n");
	return 0;
}