/* ----------------------------------------------------------------------- *
 *   
 *   Copyright 2004-2006 H. Peter Anvin - All Rights Reserved
 *
 *   Permission is hereby granted, free of charge, to any person
 *   obtaining a copy of this software and associated documentation
 *   files (the "Software"), to deal in the Software without
 *   restriction, including without limitation the rights to use,
 *   copy, modify, merge, publish, distribute, sublicense, and/or
 *   sell copies of the Software, and to permit persons to whom
 *   the Software is furnished to do so, subject to the following
 *   conditions:
 *   
 *   The above copyright notice and this permission notice shall
 *   be included in all copies or substantial portions of the Software.
 *   
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 *   OTHER DEALINGS IN THE SOFTWARE.
 *
 * ----------------------------------------------------------------------- */

/*
 * run-init.c
 *
 * Usage: exec run-init [-c /dev/console] /real-root /sbin/init "$@"
 *
 * This program should be called as the last thing in a shell script
 * acting as /init in an initramfs; it does the following:
 *
 * - Delete all files in the initramfs;
 * - Remounts /real-root onto the root filesystem;
 * - Chroots;
 * - Opens /dev/console;
 * - Spawns the specified init program (with arguments.)
 */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include "run-init.h"

static const char *program;

void __attribute__((noreturn)) die(const char *msg)
{
  fprintf(stderr, "%s: %s: %s\n", program, msg, strerror(errno));
  exit(1);
}

static void __attribute__((noreturn)) usage(void)
{
  fprintf(stderr, "Usage: exec %s [-c consoledev] /real-root /sbin/init [args]\n", program);
  exit(1);
}


int main(int argc, char *argv[])
{
  /* Command-line options and defaults */
  const char *console = "/dev/console";
  const char *realroot;
  const char *init;
  char **initargs;

  /* Variables... */
  int o;

  /* Parse the command line */
  program = argv[0];

  while ( (o = getopt(argc, argv, "c:")) != -1 ) {
    if ( o == 'c' ) {
      console = optarg;
    } else {
      usage();
    }
  }

  if ( argc-optind < 2 )
    usage();

  realroot = argv[optind];
  init     = argv[optind+1];
  initargs = argv+optind+1;

  return run_init(realroot, console, init, initargs);
}