/*************************************************************************\
*                  Copyright (C) Michael Kerrisk, 2010.                   *
*                                                                         *
* This program is free software. You may use, modify, and redistribute it *
* under the terms of the GNU Affero General Public License as published   *
* by the Free Software Foundation, either version 3 or (at your option)   *
* any later version. This program is distributed without any warranty.    *
* See the file COPYING.agpl-v3 for details.                               *
\*************************************************************************/

/* mmcopy.c

   Copy the contents of one file to another file, using memory mappings.

   Usage mmcopy source-file dest-file
*/
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "tlpi_hdr.h"

int
main(int argc, char *argv[])
{
    char *src, *dst;
    int fdSrc, fdDst;
    struct stat sb;

    if (argc != 3)
        usageErr("%s source-file dest-file\n", argv[0]);

    fdSrc = open(argv[1], O_RDONLY);
    if (fdSrc == -1)
        errExit("open");

    /* Use fstat() to obtain size of file: we use this to specify the
       size of the two mappings */

    if (fstat(fdSrc, &sb) == -1)
        errExit("fstat");

    src = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fdSrc, 0);
    if (src == MAP_FAILED)
        errExit("mmap");

    fdDst = open(argv[2], O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
    if (fdDst == -1)
        errExit("open");

    if (ftruncate(fdDst, sb.st_size) == -1)
        errExit("ftruncate");

    dst = mmap(NULL, sb.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fdDst, 0);
    if (dst == MAP_FAILED)
        errExit("mmap");

    memcpy(dst, src, sb.st_size);       /* Copy bytes between mappings */
    if (msync(src, sb.st_size, MS_SYNC) == -1)
        errExit("msync");

    exit(EXIT_SUCCESS);
}