builtins.c

grub4dos-0.4.4-2008- 08-src.zip

			tmp1 == 2 ? "2 = 1.44M floppy" :
			tmp1 == 3 ? "3 = 2.88M floppy" : "Hard Disk");

	/* No emulation mode uses 2048-byte sector size. */
	if (tmp1 == 0 && buf_geom.sector_size != 2048)
		goto failure_exec_format;

//	chainloader_file[1] = tmp1;				/* 01: boot media type */
//	chainloader_file[2] = ((tmp1 == 0) ? current_drive : (tmp1 == 4) ? 0x80 : 0x00);	/* 02: drive number */

	if (tmp1 == 0)	/* no-emulation mode */
	{
		//kernel_type = KERNEL_TYPE_CHAINLOADER;
		sprintf (chainloader_file, "(%d)%d+%d", current_drive, tmp, (i + 3) / 4);
		chainloader_load_segment = tmp2;//0x0000;
		chainloader_load_offset = 0;//0x7c00;
		chainloader_load_length = i * 512;//0x200;
		chainloader_skip_length = 0;
		chainloader_boot_CS = tmp2;//0x0000;
		chainloader_boot_IP = 0;//0x7c00;
		//chainloader_ebx = 0;
		//chainloader_ebx_set = 0;
		chainloader_edx = current_drive;
		chainloader_edx_set = 1;
		//chainloader_disable_A20 = 0;
		
		/* update lba_cd_boot if there are any maps */
		if (! unset_int13_handler (0))	/* a successful unset */
		{
			if (drive_map_slot_empty (bios_drive_map[0]))
			    if (atapi_dev_count == 0)
			    {
				errnum = ERR_NO_DRIVE_MAPPED;
				goto failure_exec_format;
			    }
			lba_cd_boot = tmp;

			set_int13_handler (bios_drive_map);
		}

		/* needn't clear disk buffer */
		/* buf_drive = -1; */
		/* buf_track = -1; */

		return ! (errnum = 0);
	}

	/* floppy or hard drive emulation. LBA=tmp */

	/*******************************************************/
	/* read the first 512 bytes of the image at 0000:7C00  */
	/*******************************************************/

	filepos = tmp * 0x800;
	
	/* we cannot use SCRATCHADDR because map_func and geometry_func may
	 * use it. So we use 1 sector below 0x2B0000 instead. */
	if (grub_read ((char *)(HMA_ADDR - 0x200), 512) != 512)
		goto failure_exec_format;

	if (tmp1 == 4)
	{
		if (probe_mbr ((struct master_and_dos_boot_sector *)(HMA_ADDR - 0x200), 0, 1, 0))
		{
			errnum = ERR_BAD_PART_TABLE;
			goto failure_exec_format;
		}
	} else {
		if (probe_bpb((struct master_and_dos_boot_sector *)(HMA_ADDR - 0x200)))
		{
			probed_total_sectors = (tmp1 == 1 ? 2400 : tmp1 == 2 ? 2880 : 5760);
		}
	}

	/* map the image */
	sprintf (chainloader_file, "--read-only --heads=0 --sectors-per-track=0 (%d)%d+%d (%d)", current_drive,
			tmp,
			(probed_total_sectors + 3) / 4, //0x3FFFFFFF,
			(tmp1 == 4) ? 0x80 : 0x00);

	tmp = ( (tmp1 == 4) ? (*(char *)0x475) : ((*(char*)0x410) & 1) );

	disable_map_info = 1;
	map_func (chainloader_file, flags);
	disable_map_info = 0;

	if (errnum)
		goto failure_exec_format;

	/* move the former fd0 or hd0 up. */
	if (tmp)
	{
		sprintf (chainloader_file, "(%d) (%d)", (tmp1 == 4) ? 0x80 : 0x00, (tmp1 == 4) ? (0x80 + tmp) : 0x01);

		map_func (chainloader_file, flags);

		if (errnum)
		{
			if (debug > 0)
			{
				printf ("Failed 'map %s'(error=%d). But you may ignore it and continue to 'boot' the CD.\n", chainloader_file, errnum);
			}
			errnum = 0;
		}
	}

	/* rehook */
	unset_int13_handler (0);
	if (drive_map_slot_empty (bios_drive_map[0]))
	    if (atapi_dev_count == 0)
	    {
		errnum = ERR_NO_DRIVE_MAPPED;
		goto failure_exec_format;
	    }
	set_int13_handler (bios_drive_map);
	buf_drive = -1;
	buf_track = -1;

        grub_memmove ((char *)0x7C00, (char *)(HMA_ADDR - 0x200), 512);
	sprintf (chainloader_file, "(%d)+1", (tmp1 == 4) ? 0x80 : 0x00);

	chainloader_load_segment = 0;//tmp2;
	chainloader_load_offset = 0x7c00;
	chainloader_load_length = 512;
	chainloader_skip_length = 0;
	chainloader_boot_CS = 0;//tmp2;
	chainloader_boot_IP = 0x7c00;
	//chainloader_ebx = 0;
	chainloader_ebx_set = 0;
	chainloader_edx_set = 0;
	//chainloader_disable_A20 = 0;
	saved_drive = ((tmp1 == 4) ? 0x80 : 0x00);
	chainloader_edx = saved_drive;
	saved_partition = ((tmp1 == 4) ? 0x00FFFF : 0xFFFFFF);
	return ! (errnum = 0);

  }
#endif /* ! GRUB_UTIL */

//  if (debug > 0)
//	printf ("Debug: chainloader_func: grub_open(%s)...", arg);

  /* Open the file.  */
  grub_open (arg);

//  if (debug > 0)
//	/* wipe out debug message. */
//	printf ("\r                                                                             \r");

  if (errnum)
	goto failure;

//  if (debug > 0)
//	printf ("Debug: chainloader_func: grub_read(512 bytes)...");

  /* Read the first block.  */
  {
    unsigned long len;
    len = grub_read ((char *) SCRATCHADDR, 512);
//    if (debug > 0)
//	/* wipe out debug message. */
//	printf ("\r                                                                             \r");

    if (len != 512)
	goto failure_exec_format;
  }

  if (chainloader_skip_length > filemax)
  {
	errnum = ERR_INVALID_SKIP_LENGTH;
	goto failure_exec_format;
  }
//  hidden_sectors = part_start;
  
  if (*((long *)SCRATCHADDR) == 0x49445324 /* $SDI */)
    {
	is_sdi = 1;
	if (debug > 0)
	    grub_printf("SDI signature: %s\n", (char *)(SCRATCHADDR));
    }
  else
  if ((*(long long *)SCRATCHADDR | 0xFF00LL) == 0x4749464E4F43FFEBLL && filemax > 0x4000)
    {

	if (chainloader_load_segment == -1)
		chainloader_load_segment = 0x0060;
	if (chainloader_load_offset == -1)
		chainloader_load_offset = 0;
	if (chainloader_load_length == -1)
		chainloader_load_length = filemax;
	if (! chainloader_ebx_set)
	{
		chainloader_ebx = current_drive | ((current_partition >> 8) & 0xFF00);
		chainloader_ebx_set = 1;
	}
	    
	grub_close ();
	
	/* FIXME: Where should the BPB be placed for FreeDOS's KERNEL.SYS?
	 *	  In the current implementation it is placed at 0000:7C00
	 *	  but has no effect, since the KERNEL.SYS body will later
	 *	  overwrite 0000:7C00 on issuing the `boot' command.
	 */
	
	if ((chainloader_ebx & 0xFF00) == 0xFF00) /* check if partition number == 0xFF */
		grub_sprintf ((char *)SCRATCHADDR, "(%d)+1", (chainloader_ebx & 0xff));
	else
		grub_sprintf ((char *)SCRATCHADDR, "(%d,%d)+1", (chainloader_ebx & 0xff), ((chainloader_ebx >> 8) & 0xff));

	if (! grub_open ((char *)SCRATCHADDR))
		goto failure;
	
	/* Read the boot sector of the partition onto 0000:7C00  */
	if (grub_read ((char *) SCRATCHADDR, 512) != 512)
		goto failure_exec_format;

	/* modify the hidden sectors */
	/* FIXME: Does the boot drive number also need modifying? */
	
	if (*((unsigned long *) (SCRATCHADDR + BOOTSEC_BPB_HIDDEN_SECTORS)))
	    *((unsigned long *) (SCRATCHADDR + BOOTSEC_BPB_HIDDEN_SECTORS)) = part_start;
	if (debug > 0)
	  grub_printf("Will boot FreeDOS from drive=0x%x, partition=0x%x(hidden sectors=0x%x)\n",
			current_drive/*(chainloader_ebx & 0x80)*/, ((current_partition >> 16) & 0xff), part_start);
    }
  else
  if (*(short *)SCRATCHADDR == 0x5A4D && filemax > 0x10000 &&
       *((unsigned short *) (SCRATCHADDR + BOOTSEC_SIG_OFFSET)) == 0
      	/* && (*(long *)(SCRATCHADDR + 0xA2)) == 0 */ )
    {

      int err;
      
      /* Read the second sector.  */
      if (grub_read ((char *) SCRATCHADDR, 512) != 512)
		goto failure_exec_format;

      err = (*(short *)SCRATCHADDR != 0x4A42);

      filepos += 0x200;	/* skip the third sector */
      
      /* Read the fourth sector.  */
      if (grub_read ((char *) SCRATCHADDR, 512) != 512)
		goto failure_exec_format;

      err |= (*((unsigned short *) (SCRATCHADDR + BOOTSEC_SIG_OFFSET)) != 0x534D);

      /* Read the fifth sector.
       * check the compress signature "CM" of IO.SYS of WinME */
      if (grub_read ((char *) SCRATCHADDR, 512) != 512)
		goto failure_exec_format;

      if (! err)
      {
	if (chainloader_load_segment == -1)
		chainloader_load_segment = 0x0070;
	if (chainloader_load_offset == -1)
		chainloader_load_offset = 0;
	if (chainloader_load_length == -1)
		chainloader_load_length = filemax;
	if (chainloader_skip_length == 0)
		chainloader_skip_length = 0x0800;

	/* WinME support by bean. Thanks! */

	// Input parameter for SYSINIT
	// BX,AX: Start sector for the data area of FAT. It doesn't needs to
	//        be set. However, we should at least clear BX, otherwise,
	//        it would have some minor problem when booting WinME.
	// DI:    Length of the boot code, don't need to be set.
	// BP:    0x7C00, boot sector pointer, don't need to be set.
	// DH:    Media ID (BS[0x15]) , 0xF0 for floppy, 0xF8 for harddisk
	// DL:    Drive number (BS[0x40] for FAT32)

	if (! chainloader_edx_set)
	{
		chainloader_edx = current_drive | ((current_partition >> 8) & 0xFF00);
		chainloader_edx_set = 1;
	}
	if (! chainloader_ebx_set)
	{
		chainloader_ebx = 0;	// clear BX for WinME
		chainloader_ebx_set = 1;
	}
	    
	/* save partition number to the high word */
	chainloader_edx = (chainloader_edx & 0xFF00FFFF) | ((chainloader_edx & 0xFF00) << 8);
	
	// set media descriptor in DH for WinME
	chainloader_edx = (chainloader_edx & 0xFFFF00FF) | 0xF000 | ((chainloader_edx & 0x80) << 4);
		
	grub_close ();
	
	/* FIXME: Where should the BPB be placed for MS-DOS's IO.SYS?
	 *	  In the current implementation it is placed at 0000:7C00
	 *	  but has no effect, since the IO.SYS body will later
	 *	  overwrite 0000:7C00 on issuing the `boot' command.
	 */
	
	if ((chainloader_edx & 0xFF0000) == 0xFF0000) /* check if partition number == 0xFF */
		grub_sprintf ((char *)SCRATCHADDR, "(%d)+1", (chainloader_edx & 0xff));
	else
		grub_sprintf ((char *)SCRATCHADDR, "(%d,%d)+1", (chainloader_edx & 0xff), ((chainloader_edx >> 16) & 0xff));

	if (! grub_open ((char *)SCRATCHADDR))
		goto failure;
	
	/* Read the boot sector of the partition onto 0000:7C00  */
	if (grub_read ((char *) SCRATCHADDR, 512) != 512)
		goto failure_exec_format;

	/* modify the hidden sectors */
	/* FIXME: Does the boot drive number also need modifying? */
	
	if (*((unsigned long *) (SCRATCHADDR + BOOTSEC_BPB_HIDDEN_SECTORS)))
	    *((unsigned long *) (SCRATCHADDR + BOOTSEC_BPB_HIDDEN_SECTORS)) = part_start;
	if (debug > 0)
	  grub_printf("Will boot MS-DOS %c.x from drive=0x%x, partition=0x%x(hidden sectors=0x%x)\n",
			((*(unsigned short *) SCRATCHADDR) == 0x4D43)? '8' : '7',
			current_drive/*(chainloader_edx & 0x80)*/, ((current_partition >> 16) & 0xff), part_start);
      }
    }
  else
  if (((*(long *)SCRATCHADDR) & 0x00FF00FF) == 0x000100E9 && filemax > 0x30000 &&
       (*((unsigned short *) (SCRATCHADDR + BOOTSEC_SIG_OFFSET)) != BOOTSEC_SIGNATURE))
    {
//grub_printf("current_drive=0x%x, current_partition=0x%x(part_start=0x%x)\n", current_drive, current_partition, part_start);
	if (chainloader_load_segment == -1)
		chainloader_load_segment = 0x2000;
	if (chainloader_load_offset == -1)
		chainloader_load_offset = 0;
	if (chainloader_load_length == -1)
		chainloader_load_length = filemax;
	if (! chainloader_edx_set)
	{
		chainloader_edx = current_drive | ((current_partition >> 8) & 0xFF00);
		chainloader_edx_set = 1;
	}
	    
	grub_close ();
	
	if ((chainloader_edx & 0xFF00) == 0xFF00)
		grub_sprintf ((char *)SCRATCHADDR, "(%d)+1", (chainloader_edx & 0xff));
	else
		grub_sprintf ((char *)SCRATCHADDR, "(%d,%d)+1", (chainloader_edx & 0xff), ((chainloader_edx >> 8) & 0xff));

	if (! grub_open ((char *)SCRATCHADDR))
		goto failure;
	
	/* Read the boot sector of the partition onto 0000:7C00  */
	if (grub_read ((char *) SCRATCHADDR, SECTOR_SIZE) != SECTOR_SIZE)
		goto failure_exec_format;

//grub_printf("current_drive=0x%x, current_partition=0x%x(part_start=0x%x)\n", current_drive, current_partition, part_start);
	/* modify the hidden sectors */
	/* FIXME: Does the boot drive number also need modifying? */
	
	if (*((unsigned long *) (SCRATCHADDR + BOOTSEC_BPB_HIDDEN_SECTORS)))
	    *((unsigned long *) (SCRATCHADDR + BOOTSEC_BPB_HIDDEN_SECTORS)) = part_start;
	if (debug > 0)
	  grub_printf("Will boot NTLDR from drive=0x%x, partition=0x%x(hidden sectors=0x%x)\n", current_drive, ((current_partition >> 16) & 0xff), part_start);
    }
  else
  if (((*(long long *)SCRATCHADDR) & 0xFFFFFFFFFFFFLL) == 0x7C40EAFALL && filemax > 0x2000 && filemax < 0x20000 &&
       (*((unsigned short *) (SCRATCHADDR + 0x40)) == 0x892E) &&
       (*((unsigned short *) (SCRATCHADDR + 0x45)) == 0x8C2E) &&
       (*((unsigned long *) (SCRATCHADDR + 0x4A)) == 0xD08EC031) &&
       (*((unsigned long *) (SCRATCHADDR + 0x4E)) == 0x8E7BD4BC)
     )
    {
	if (buf_geom.sector_size != 2048)
	{
		if (debug > 0)
			printf ("\nCannot chainload ISOLINUX from a non-CDROM device.\n");
		goto failure_exec_format;
	}

	chainloader_load_segment = 0;
	chainloader_load_offset = 0x7c00;
	chainloader_load_length = filemax;
	chainloader_edx = current_drive;
	chainloader_edx_set = 1;

	is_isolinux = 1;
    }
  else
  /* If not loading it forcibly, check for the signature.  */
  if (! force
      && (*((unsigned short *) (SCRATCHADDR + BOOTSEC_SIG_OFFSET))
	  != BOOTSEC_SIGNATURE))
	goto failure_exec_format;

  grub_close ();

  /* if BPB exists, we can reliablly modify the hidden sectors. */
  if (! probe_bpb((struct master_and_dos_boot_sector *)SCRATCHADDR))
    if (*((unsigned long *) (SCRATCHADDR + BOOTSEC_BPB_HIDDEN_SECTORS)))
        *((unsigned long *) (SCRATCHADDR + BOOTSEC_BPB_HIDDEN_SECTORS))
          = part_start;

  if (chainloader_load_length == -1)
	  chainloader_load_length = filemax;
  if (chainloader_load_length > 0xA0000)
	  chainloader_load_length = 0xA0000;
  
  grub_memmove ((char *)0x7C00, (char *)SCRATCHADDR, 512);
  errnum = ERR_NONE;
  
  return 1;

failure_exec_format:

  grub_close ();

  if (errnum == ERR_NONE)
	errnum = ERR_EXEC_FORMAT;

failure:

  chainloader_load_segment = chainloader_load_segment_orig;
  chainloader_load_offset = chainloader_load_offset_orig;
  chainloader_load_length = chainloader_load_length_orig;
  chainloader_skip_length = chainloader_skip_length_orig;
  chainloader_boot_CS = chainloader_boot_CS_orig;
  chainloader_boot_IP = chainloader_boot_IP_orig;
  chainloader_ebx = chainloader_ebx_orig;
  chainloader_ebx_set = chainloader_ebx_set_orig;
  chainloader_edx = chainloader_edx_orig;
  chainloader_edx_set = chainloader_edx_set_orig;
  chainloader_disable_A20 = chainloader_disable_A20_orig;
  is_sdi = is_sdi_orig;
  is_raw = is_raw_orig;
  is_isolinux = is_isolinux_orig;
  kernel_type = kernel_type_orig;
  force = errnum;	/* backup the errnum */
  grub_memmove ((char *)chainloader_file, (char *)chainloader_file_orig, sizeof(chainloader_file));
  errnum = force;	/* restore the errnum */
  return 0;		/* return failure */

}

static struct builtin builtin_chainloader =
{
  "chainloader",
  chainloader_func,
  BUILTIN_MENU | BUILTIN_CMDLINE | BUILTIN_HELP_LIST,
  "chainloader [--force] [--load-segment=LS] [--load-offset=LO]"
  "\n[--load-length=LL] [--skip-length=SL] [--boot-cs=CS] [--boot-ip=IP]"
  "\n[--ebx=EBX] [--edx=EDX] [--sdi] [--disable-a20] FILE",
  "Load the chain-loader FILE. If --force is specified, then load it"
  " forcibly, whether the boot loader signature is present or not."
  " LS:LO specifies the load address other than 0000:7C00. LL specifies"
  " the length of the boot image(between 512 and 640K). CS:IP specifies"
  " the address where the boot image will gain control. EBX/EDX specifies"
  " the EBX/EDX register value when the boot image gets control. Use --sdi"
  " if FILE is a System Deployment Image, which is of the Windows XP"
  " RAM boot file format. Use --disable-a20 if you wish to turn off"
  " A20 when transferring cont