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(void)
      31  {
      32  	FILE *out = stdout;
      33  	fputs(USAGE_HEADER, out);
      34  	fprintf(out, _(" %s [options] new_root put_old\n"),
      35  		program_invocation_short_name);
      36  
      37  	fputs(USAGE_SEPARATOR, out);
      38  	fputs(_("Change the root filesystem.\n"), out);
      39  
      40  	fputs(USAGE_OPTIONS, out);
      41  	printf(USAGE_HELP_OPTIONS(16));
      42  	printf(USAGE_MAN_TAIL("pivot_root(8)"));
      43  	exit(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  	close_stdout_atexit();
      59  
      60  	while ((ch = getopt_long(argc, argv, "Vh", longopts, NULL)) != -1)
      61  		switch (ch) {
      62  		case 'V':
      63  			print_version(EXIT_SUCCESS);
      64  		case 'h':
      65  			usage();
      66  		default:
      67  			errtryhelp(EXIT_FAILURE);
      68  		}
      69  
      70  	if (argc != 3) {
      71  		warnx(_("bad usage"));
      72  		errtryhelp(EXIT_FAILURE);
      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  }