grub-setup.c

有助于了解操作系统如何启动之过程

		{
		  fwrite (core_img, 1, core_size, dump2);
		  fclose (dump2);
		}
	      
#endif      
	      grub_util_info ("succeeded in opening the core image but the data is different");
	    }
	  else
	    {
	      grub_file_close (file);
	      break;
	    }

	  grub_file_close (file);
	}
      else
	grub_util_info ("couldn't open the core image");

      if (grub_errno)
	grub_util_info ("error message = %s", grub_errmsg);
      
      grub_errno = GRUB_ERR_NONE;
      sync ();
      sleep (1);
    }

  if (i == MAX_TRIES)
    grub_util_error ("Cannot read `%s' correctly", core_path);

  /* Clean out the blocklists.  */
  block = first_block;
  while (block->len)
    {
      block->start = 0;
      block->len = 0;
      block->segment = 0;

      block--;
      
      if ((char *) block <= core_img)
	grub_util_error ("No terminator in the core image");
    }
  
  /* Now read the core image to determine where the sectors are.  */
  file = grub_file_open (core_path);
  if (! file)
    grub_util_error ("%s", grub_errmsg);
  
  file->read_hook = save_first_sector;
  if (grub_file_read (file, tmp_img, GRUB_DISK_SECTOR_SIZE)
      != GRUB_DISK_SECTOR_SIZE)
    grub_util_error ("Failed to read the first sector of the core image");

  block = first_block;
  file->read_hook = save_blocklists;
  if (grub_file_read (file, tmp_img, core_size - GRUB_DISK_SECTOR_SIZE)
      != (grub_ssize_t) core_size - GRUB_DISK_SECTOR_SIZE)
    grub_util_error ("Failed to read the rest sectors of the core image");

  grub_file_close (file);
  
  free (core_path);
  free (tmp_img);
  
  *kernel_sector = grub_cpu_to_le64 (first_sector);

  /* If the destination device is different from the root device,
     it is necessary to embed the boot drive explicitly.  */
  if (root_dev->disk->id != dest_dev->disk->id)
    *boot_drive = (grub_uint8_t) root_dev->disk->id;
  else
    *boot_drive = 0xFF;

  /* Embed information about the installed location.  */
  if (root_dev->disk->partition)
    {
      struct grub_pc_partition *pcdata =
	root_dev->disk->partition->data;

	if (strcmp (root_dev->disk->partition->partmap->name,
		  "pc_partition_map") == 0)
	  {
	    *install_dos_part
	      = grub_cpu_to_le32 (pcdata->dos_part);
	    *install_bsd_part
	      = grub_cpu_to_le32 (pcdata->bsd_part);
	  }
	else if (strcmp (root_dev->disk->partition->partmap->name,
		  "gpt_partition_map") == 0)
	  {
	    *install_dos_part = grub_cpu_to_le32 (root_dev->disk->partition->index);
	    *install_bsd_part = grub_cpu_to_le32 (-1);
	  }
	else
	  grub_util_error ("No PC style partitions found");
    }
  else
    *install_dos_part = *install_bsd_part = grub_cpu_to_le32 (-1);

  grub_util_info ("dos partition is %d, bsd partition is %d, prefix is %s",
		  grub_le_to_cpu32 (*install_dos_part),
		  grub_le_to_cpu32 (*install_bsd_part),
		  prefix);
  strcpy (install_prefix, prefix);
  
  /* Write the first two sectors of the core image onto the disk.  */
  core_path = grub_util_get_path (dir, core_file);
  grub_util_info ("opening the core image `%s'", core_path);
  fp = fopen (core_path, "r+b");
  if (! fp)
    grub_util_error ("Cannot open `%s'", core_path);

  grub_util_write_image (core_img, GRUB_DISK_SECTOR_SIZE * 2, fp);
  fclose (fp);
  free (core_path);

  /* Write the boot image onto the disk.  */
  if (grub_disk_write (dest_dev->disk, 0, 0, GRUB_DISK_SECTOR_SIZE, boot_img))
    grub_util_error ("%s", grub_errmsg);

 finish:

  /* Sync is a Good Thing.  */
  sync ();
  
  free (core_img);
  free (boot_img);
  grub_device_close (dest_dev);
  if (!must_embed)
    grub_device_close (root_dev);
}

static struct option options[] =
  {
    {"boot-image", required_argument, 0, 'b'},
    {"core-image", required_argument, 0, 'c'},
    {"directory", required_argument, 0, 'd'},
    {"device-map", required_argument, 0, 'm'},
    {"root-device", required_argument, 0, 'r'},
    {"help", no_argument, 0, 'h'},
    {"version", no_argument, 0, 'V'},
    {"verbose", no_argument, 0, 'v'},
    {0, 0, 0, 0}
  };

static void
usage (int status)
{
  if (status)
    fprintf (stderr, "Try ``grub-setup --help'' for more information.\n");
  else
    printf ("\
Usage: grub-setup [OPTION]... DEVICE\n\
\n\
Set up images to boot from DEVICE.\n\
DEVICE must be a GRUB device (e.g. ``(hd0,1)'').\n\
\n\
  -b, --boot-image=FILE   use FILE as the boot image [default=%s]\n\
  -c, --core-image=FILE   use FILE as the core image [default=%s]\n\
  -d, --directory=DIR     use GRUB files in the directory DIR [default=%s]\n\
  -m, --device-map=FILE   use FILE as the device map [default=%s]\n\
  -r, --root-device=DEV   use DEV as the root device [default=guessed]\n\
  -h, --help              display this message and exit\n\
  -V, --version           print version information and exit\n\
  -v, --verbose           print verbose messages\n\
\n\
Report bugs to <%s>.\n\
",
	    DEFAULT_BOOT_FILE, DEFAULT_CORE_FILE, DEFAULT_DIRECTORY,
	    DEFAULT_DEVICE_MAP, PACKAGE_BUGREPORT);

  exit (status);
}

static char *
get_device_name (char *dev)
{
  size_t len = strlen (dev);
  
  if (dev[0] != '(' || dev[len - 1] != ')')
    return 0;

  dev[len - 1] = '\0';
  return dev + 1;
}

int
main (int argc, char *argv[])
{
  char *boot_file = 0;
  char *core_file = 0;
  char *dir = 0;
  char *dev_map = 0;
  char *root_dev = 0;
  char *prefix;
  char *dest_dev;
  int must_embed = 0;
  
  progname = "grub-setup";

  /* Check for options.  */
  while (1)
    {
      int c = getopt_long (argc, argv, "b:c:d:m:r:hVv", options, 0);

      if (c == -1)
	break;
      else
	switch (c)
	  {
	  case 'b':
	    if (boot_file)
	      free (boot_file);

	    boot_file = xstrdup (optarg);
	    break;

	  case 'c':
	    if (core_file)
	      free (core_file);

	    core_file = xstrdup (optarg);
	    break;

	  case 'd':
	    if (dir)
	      free (dir);

	    dir = xstrdup (optarg);
	    break;
	    
	  case 'm':
	    if (dev_map)
	      free (dev_map);

	    dev_map = xstrdup (optarg);
	    break;

	  case 'r':
	    if (root_dev)
	      free (root_dev);

	    root_dev = xstrdup (optarg);
	    break;
	    
	  case 'h':
	    usage (0);
	    break;

	  case 'V':
	    printf ("grub-setup (%s) %s\n", PACKAGE_NAME, PACKAGE_VERSION);
	    return 0;

	  case 'v':
	    verbosity++;
	    break;

	  default:
	    usage (1);
	    break;
	  }
    }

  /* Obtain DEST_DEV.  */
  if (optind >= argc)
    {
      fprintf (stderr, "No device is specified.\n");
      usage (1);
    }

  if (optind + 1 != argc)
    {
      fprintf (stderr, "Unknown extra argument `%s'.\n", argv[optind + 1]);
      usage (1);
    }

  /* Initialize the emulated biosdisk driver.  */
  grub_util_biosdisk_init (dev_map ? : DEFAULT_DEVICE_MAP);

  /* Initialize all modules. */
  grub_init_all ();
  
  dest_dev = get_device_name (argv[optind]);
  if (! dest_dev)
    {
      /* Possibly, the user specified an OS device file.  */
      dest_dev = grub_util_get_grub_dev (argv[optind]);
      if (! dest_dev)
	{
	  fprintf (stderr, "Invalid device `%s'.\n", argv[optind]);
	  usage (1);
	}
    }
  else
    /* For simplicity.  */
    dest_dev = xstrdup (dest_dev);

  prefix = grub_get_prefix (dir ? : DEFAULT_DIRECTORY);
  
  if (root_dev)
    {
      char *tmp = get_device_name (root_dev);

      if (! tmp)
	grub_util_error ("Invalid root device `%s'", root_dev);
      
      tmp = xstrdup (tmp);
      free (root_dev);
      root_dev = tmp;
    }
  else
    {
      root_dev = grub_util_get_grub_dev (grub_guess_root_device (dir ? : DEFAULT_DIRECTORY));
      if (! root_dev)
	{
	  grub_util_info ("guessing the root device failed, because of `%s'",
			  grub_errmsg);
	  grub_util_error ("Cannot guess the root device. Specify the option ``--root-device''.");
	}
    }

#ifdef __linux__
  if (grub_util_lvm_isvolume (root_dev))
    {
      char *newprefix;
      must_embed = 1;

      newprefix = xmalloc (1 + strlen (root_dev) + 1 + strlen (prefix) + 1);
      sprintf (newprefix, "(%s)%s", root_dev, prefix);
      free (prefix);
      prefix = newprefix;
    }
    
  if (dest_dev[0] == 'm' && dest_dev[1] == 'd'
      && dest_dev[2] >= '0' && dest_dev[2] <= '9')
    {
      char **devicelist;
      char *raid_prefix;
      int i;

      raid_prefix = xmalloc (1 + strlen (dest_dev) + 1 + strlen (prefix) + 1);

      sprintf (raid_prefix, "(%s)%s", dest_dev, prefix);
      
      devicelist = grub_util_raid_getmembers (dest_dev);

      for (i = 0; devicelist[i]; i++)
	{
	  setup (raid_prefix,
		 dir ? : DEFAULT_DIRECTORY,
		 boot_file ? : DEFAULT_BOOT_FILE,
		 core_file ? : DEFAULT_CORE_FILE,
		 root_dev, grub_util_get_grub_dev (devicelist[i]), 1);
	}

      free (raid_prefix);
    }
  else
#endif
  /* Do the real work.  */
    setup (prefix,
	   dir ? : DEFAULT_DIRECTORY,
	   boot_file ? : DEFAULT_BOOT_FILE,
	   core_file ? : DEFAULT_CORE_FILE,
	   root_dev, dest_dev, must_embed);

  /* Free resources.  */
  grub_fini_all ();
  grub_util_biosdisk_fini ();
  
  free (boot_file);
  free (core_file);
  free (dir);
  free (dev_map);
  free (root_dev);
  free (prefix);
  free (dest_dev);
  
  return 0;
}