sys-utils/pivot_root.c

   1 /*
   2  * pivot_root.c - Change the root file system
   3  *
   4  * Copyright (C) 2000 Werner Almesberger
   5  *
   6  * This file is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This file is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16 #include <err.h>
  17 #include <errno.h>
  18 #include <getopt.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <sys/syscall.h>
  22 #include <unistd.h>
  23
  24 #include "c.h"
  25 #include "nls.h"
  26 #include "closestream.h"
  27
  28 #define pivot_root(new_root,put_old) syscall(SYS_pivot_root,new_root,put_old)
  29
  30 static void __attribute__ ((__noreturn__)) usage(FILE * out)
  31 {
  32         fprintf(out, USAGE_HEADER);
  33         fprintf(out, _(" %s [options] new_root put_old\n"),
  34                 program_invocation_short_name);
  35
  36         fputs(USAGE_SEPARATOR, out);
  37         fputs(_("Change the root filesystem.\n"), out);
  38
  39         fprintf(out, USAGE_OPTIONS);
  40         fprintf(out, USAGE_HELP);
  41         fprintf(out, USAGE_VERSION);
  42         fprintf(out, USAGE_MAN_TAIL("pivot_root(8)"));
  43         exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
  44 }
  45
  46 int main(int argc, char **argv)
  47 {
  48         int ch;
  49         static const struct option longopts[] = {
  50                 {"version", no_argument, NULL, 'V'},
  51                 {"help", no_argument, NULL, 'h'},
  52                 {NULL, 0, NULL, 0}
  53         };
  54
  55         setlocale(LC_ALL, "");
  56         bindtextdomain(PACKAGE, LOCALEDIR);
  57         textdomain(PACKAGE);
  58         atexit(close_stdout);
  59
  60         while ((ch = getopt_long(argc, argv, "Vh", longopts, NULL)) != -1)
  61                 switch (ch) {
  62                 case 'V':
  63                         printf(UTIL_LINUX_VERSION);
  64                         return EXIT_SUCCESS;
  65                 case 'h':
  66                         usage(stdout);
  67                 default:
  68                         errtryhelp(EXIT_FAILURE);
  69                 }
  70
  71         if (argc != 3)
  72                 usage(stderr);
  73
  74         if (pivot_root(argv[1], argv[2]) < 0)
  75                 err(EXIT_FAILURE, _("failed to change root from `%s' to `%s'"),
  76                     argv[1], argv[2]);
  77
  78         return EXIT_SUCCESS;
  79 }