disk/memdisk.c

   1 /* memdisk.c - Access embedded memory disk.  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2007,2008  Free Software Foundation, Inc.
   5  *
   6  *  GRUB 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 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB 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  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/disk.h>
  21 #include <grub/dl.h>
  22 #include <grub/kernel.h>
  23 #include <grub/misc.h>
  24 #include <grub/mm.h>
  25 #include <grub/types.h>
  26 #include <grub/machine/kernel.h>
  27
  28 static char *memdisk_addr;
  29 static grub_off_t memdisk_size = 0;
  30
  31 static int
  32 grub_memdisk_iterate (int (*hook) (const char *name))
  33 {
  34   return hook ("memdisk");
  35 }
  36
  37 static grub_err_t
  38 grub_memdisk_open (const char *name, grub_disk_t disk)
  39 {
  40   if (grub_strcmp (name, "memdisk"))
  41       return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a memdisk");
  42
  43   disk->total_sectors = memdisk_size / GRUB_DISK_SECTOR_SIZE;
  44   disk->id = (unsigned long) "mdsk";
  45   disk->has_partitions = 0;
  46
  47   return GRUB_ERR_NONE;
  48 }
  49
  50 static void
  51 grub_memdisk_close (grub_disk_t disk __attribute((unused)))
  52 {
  53 }
  54
  55 static grub_err_t
  56 grub_memdisk_read (grub_disk_t disk __attribute((unused)), grub_disk_addr_t sector,
  57                     grub_size_t size, char *buf)
  58 {
  59   grub_memcpy (buf, memdisk_addr + (sector << GRUB_DISK_SECTOR_BITS), size << GRUB_DISK_SECTOR_BITS);
  60   return 0;
  61 }
  62
  63 static grub_err_t
  64 grub_memdisk_write (grub_disk_t disk __attribute((unused)), grub_disk_addr_t sector,
  65                      grub_size_t size, const char *buf)
  66 {
  67   grub_memcpy (memdisk_addr + (sector << GRUB_DISK_SECTOR_BITS), buf, size << GRUB_DISK_SECTOR_BITS);
  68   return 0;
  69 }
  70
  71 static struct grub_disk_dev grub_memdisk_dev =
  72   {
  73     .name = "memdisk",
  74     .id = GRUB_DISK_DEVICE_MEMDISK_ID,
  75     .iterate = grub_memdisk_iterate,
  76     .open = grub_memdisk_open,
  77     .close = grub_memdisk_close,
  78     .read = grub_memdisk_read,
  79     .write = grub_memdisk_write,
  80     .next = 0
  81   };
  82
  83 GRUB_MOD_INIT(memdisk)
  84 {
  85   auto int hook (struct grub_module_header *);
  86   int hook (struct grub_module_header *header)
  87     {
  88       if (header->type == OBJ_TYPE_MEMDISK)
  89         {
  90           char *memdisk_orig_addr;
  91           memdisk_orig_addr = (char *) header + sizeof (struct grub_module_header);
  92
  93           grub_dprintf ("memdisk", "Found memdisk image at %p\n", memdisk_orig_addr);
  94
  95           memdisk_size = header->size - sizeof (struct grub_module_header);
  96           memdisk_addr = grub_malloc (memdisk_size);
  97
  98           grub_dprintf ("memdisk", "Copying memdisk image to dynamic memory\n");
  99           grub_memmove (memdisk_addr, memdisk_orig_addr, memdisk_size);
 100
 101           grub_disk_dev_register (&grub_memdisk_dev);
 102           return 1;
 103         }
 104
 105       return 0;
 106     }
 107
 108   grub_module_iterate (hook);
 109 }
 110
 111 GRUB_MOD_FINI(memdisk)
 112 {
 113   if (! memdisk_size)
 114     return;
 115   grub_free (memdisk_addr);
 116   grub_disk_dev_unregister (&grub_memdisk_dev);
 117 }