arch/all-pc/boot/grub2-aros/grub-core/disk/loopback.c

   1 /* loopback.c - command to add loopback devices.  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2005,2006,2007  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/dl.h>
  21 #include <grub/misc.h>
  22 #include <grub/file.h>
  23 #include <grub/disk.h>
  24 #include <grub/mm.h>
  25 #include <grub/extcmd.h>
  26 #include <grub/i18n.h>
  27
  28 GRUB_MOD_LICENSE ("GPLv3+");
  29
  30 struct grub_loopback
  31 {
  32   char *devname;
  33   grub_file_t file;
  34   struct grub_loopback *next;
  35   unsigned long id;
  36 };
  37
  38 static struct grub_loopback *loopback_list;
  39 static unsigned long last_id = 0;
  40
  41 static const struct grub_arg_option options[] =
  42   {
  43     /* TRANSLATORS: The disk is simply removed from the list of available ones,
  44        not wiped, avoid to scare user.  */
  45     {"delete", 'd', 0, N_("Delete the specified loopback drive."), 0, 0},
  46     {0, 0, 0, 0, 0, 0}
  47   };
  48
  49 /* Delete the loopback device NAME.  */
  50 static grub_err_t
  51 delete_loopback (const char *name)
  52 {
  53   struct grub_loopback *dev;
  54   struct grub_loopback **prev;
  55
  56   /* Search for the device.  */
  57   for (dev = loopback_list, prev = &loopback_list;
  58        dev;
  59        prev = &dev->next, dev = dev->next)
  60     if (grub_strcmp (dev->devname, name) == 0)
  61       break;
  62
  63   if (! dev)
  64     return grub_error (GRUB_ERR_BAD_DEVICE, "device not found");
  65
  66   /* Remove the device from the list.  */
  67   *prev = dev->next;
  68
  69   grub_free (dev->devname);
  70   grub_file_close (dev->file);
  71   grub_free (dev);
  72
  73   return 0;
  74 }
  75
  76 /* The command to add and remove loopback devices.  */
  77 static grub_err_t
  78 grub_cmd_loopback (grub_extcmd_context_t ctxt, int argc, char **args)
  79 {
  80   struct grub_arg_list *state = ctxt->state;
  81   grub_file_t file;
  82   struct grub_loopback *newdev;
  83   grub_err_t ret;
  84
  85   if (argc < 1)
  86     return grub_error (GRUB_ERR_BAD_ARGUMENT, "device name required");
  87
  88   /* Check if `-d' was used.  */
  89   if (state[0].set)
  90       return delete_loopback (args[0]);
  91
  92   if (argc < 2)
  93     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
  94
  95   file = grub_file_open (args[1]);
  96   if (! file)
  97     return grub_errno;
  98
  99   /* First try to replace the old device.  */
 100   for (newdev = loopback_list; newdev; newdev = newdev->next)
 101     if (grub_strcmp (newdev->devname, args[0]) == 0)
 102       break;
 103
 104   if (newdev)
 105     {
 106       grub_file_close (newdev->file);
 107       newdev->file = file;
 108
 109       return 0;
 110     }
 111
 112   /* Unable to replace it, make a new entry.  */
 113   newdev = grub_malloc (sizeof (struct grub_loopback));
 114   if (! newdev)
 115     goto fail;
 116
 117   newdev->devname = grub_strdup (args[0]);
 118   if (! newdev->devname)
 119     {
 120       grub_free (newdev);
 121       goto fail;
 122     }
 123
 124   newdev->file = file;
 125   newdev->id = last_id++;
 126
 127   /* Add the new entry to the list.  */
 128   newdev->next = loopback_list;
 129   loopback_list = newdev;
 130
 131   return 0;
 132
 133 fail:
 134   ret = grub_errno;
 135   grub_file_close (file);
 136   return ret;
 137 }
 138
 139 \f
 140 static int
 141 grub_loopback_iterate (grub_disk_dev_iterate_hook_t hook, void *hook_data,
 142                        grub_disk_pull_t pull)
 143 {
 144   struct grub_loopback *d;
 145   if (pull != GRUB_DISK_PULL_NONE)
 146     return 0;
 147   for (d = loopback_list; d; d = d->next)
 148     {
 149       if (hook (d->devname, hook_data))
 150         return 1;
 151     }
 152   return 0;
 153 }
 154
 155 static grub_err_t
 156 grub_loopback_open (const char *name, grub_disk_t disk)
 157 {
 158   struct grub_loopback *dev;
 159
 160   for (dev = loopback_list; dev; dev = dev->next)
 161     if (grub_strcmp (dev->devname, name) == 0)
 162       break;
 163
 164   if (! dev)
 165     return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "can't open device");
 166
 167   /* Use the filesize for the disk size, round up to a complete sector.  */
 168   if (dev->file->size != GRUB_FILE_SIZE_UNKNOWN)
 169     disk->total_sectors = ((dev->file->size + GRUB_DISK_SECTOR_SIZE - 1)
 170                            / GRUB_DISK_SECTOR_SIZE);
 171   else
 172     disk->total_sectors = GRUB_DISK_SIZE_UNKNOWN;
 173   /* Avoid reading more than 512M.  */
 174   disk->max_agglomerate = 1 << (29 - GRUB_DISK_SECTOR_BITS
 175                                 - GRUB_DISK_CACHE_BITS);
 176
 177   disk->id = dev->id;
 178
 179   disk->data = dev;
 180
 181   return 0;
 182 }
 183
 184 static grub_err_t
 185 grub_loopback_read (grub_disk_t disk, grub_disk_addr_t sector,
 186                     grub_size_t size, char *buf)
 187 {
 188   grub_file_t file = ((struct grub_loopback *) disk->data)->file;
 189   grub_off_t pos;
 190
 191   grub_file_seek (file, sector << GRUB_DISK_SECTOR_BITS);
 192
 193   grub_file_read (file, buf, size << GRUB_DISK_SECTOR_BITS);
 194   if (grub_errno)
 195     return grub_errno;
 196
 197   /* In case there is more data read than there is available, in case
 198      of files that are not a multiple of GRUB_DISK_SECTOR_SIZE, fill
 199      the rest with zeros.  */
 200   pos = (sector + size) << GRUB_DISK_SECTOR_BITS;
 201   if (pos > file->size)
 202     {
 203       grub_size_t amount = pos - file->size;
 204       grub_memset (buf + (size << GRUB_DISK_SECTOR_BITS) - amount, 0, amount);
 205     }
 206
 207   return 0;
 208 }
 209
 210 static grub_err_t
 211 grub_loopback_write (grub_disk_t disk __attribute ((unused)),
 212                      grub_disk_addr_t sector __attribute ((unused)),
 213                      grub_size_t size __attribute ((unused)),
 214                      const char *buf __attribute ((unused)))
 215 {
 216   return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
 217                      "loopback write is not supported");
 218 }
 219
 220 static struct grub_disk_dev grub_loopback_dev =
 221   {
 222     .name = "loopback",
 223     .id = GRUB_DISK_DEVICE_LOOPBACK_ID,
 224     .iterate = grub_loopback_iterate,
 225     .open = grub_loopback_open,
 226     .read = grub_loopback_read,
 227     .write = grub_loopback_write,
 228     .next = 0
 229   };
 230
 231 static grub_extcmd_t cmd;
 232
 233 GRUB_MOD_INIT(loopback)
 234 {
 235   cmd = grub_register_extcmd ("loopback", grub_cmd_loopback, 0,
 236                               N_("[-d] DEVICENAME FILE."),
 237                               /* TRANSLATORS: The file itself is not destroyed
 238                                  or transformed into drive.  */
 239                               N_("Make a virtual drive from a file."), options);
 240   grub_disk_dev_register (&grub_loopback_dev);
 241 }
 242
 243 GRUB_MOD_FINI(loopback)
 244 {
 245   grub_unregister_extcmd (cmd);
 246   grub_disk_dev_unregister (&grub_loopback_dev);
 247 }