#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

#ifndef MAP_FILE
# define MAP_FILE 0
#endif

int
main(argc, argv)
    int argc;
    char *argv[];
{
    int fdin, fdout;
    char *src, *dst;
    struct stat statbuf;

    if (argc!=3) {
	fprintf(stderr, "bad boy, need 2 args (in, out)\b");
	exit(27);
    }

    if ((fdin = open(argv[1], O_RDONLY)) < 0) {
	perror("input vomit");
	exit(31);
    }

    if ((fdout = open(argv[2], O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0) {
	fprintf(stderr, "output sodomy");
	exit(119);
    }

    if (fstat(fdin, &statbuf) < 0) {
	perror("stat misthap");
	exit(311);
    }

    /* set size of output file */
    if (lseek(fdout, statbuf.st_size -1, SEEK_SET) < 0) {
	perror("seek him far and wide");
	exit(7);
    }

    if (write(fdout, "", 1) != 1) {
	perror("write home again");
	exit(19);
    }


    if ((src = mmap(
	0,
	statbuf.st_size,
	PROT_READ,
	MAP_FILE|MAP_SHARED,
	fdin,
	0
    )) == (caddr_t) -1) {
	perror("lost reading input");
	exit(13);
    }

    if ((dst = mmap(
	0,
	statbuf.st_size,
	PROT_READ|PROT_WRITE,
	MAP_FILE|MAP_SHARED,
	fdout,
	0
    )) == (caddr_t) -1) {
	perror("lost my way");
	exit(17);
    }

    memcpy(dst, src, statbuf.st_size);

    exit(0);

}