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/* loopback.c - command to add loopback devices. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2005,2006,2007 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/dl.h>
#include <grub/misc.h>
#include <grub/file.h>
#include <grub/disk.h>
#include <grub/mm.h>
#include <grub/extcmd.h>
#include <grub/i18n.h>
GRUB_MOD_LICENSE ("GPLv3+");
struct grub_loopback
{
char *devname;
grub_file_t file;
struct grub_loopback *next;
unsigned long id;
};
static struct grub_loopback *loopback_list;
static unsigned long last_id = 0;
static const struct grub_arg_option options[] =
{
/* TRANSLATORS: The disk is simply removed from the list of available ones,
not wiped, avoid to scare user. */
{"delete", 'd', 0, N_("Delete the specified loopback drive."), 0, 0},
{0, 0, 0, 0, 0, 0}
};
/* Delete the loopback device NAME. */
static grub_err_t
delete_loopback (const char *name)
{
struct grub_loopback *dev;
struct grub_loopback **prev;
/* Search for the device. */
for (dev = loopback_list, prev = &loopback_list;
dev;
prev = &dev->next, dev = dev->next)
if (grub_strcmp (dev->devname, name) == 0)
break;
if (! dev)
return grub_error (GRUB_ERR_BAD_DEVICE, "device not found");
/* Remove the device from the list. */
*prev = dev->next;
grub_free (dev->devname);
grub_file_close (dev->file);
grub_free (dev);
return 0;
}
/* The command to add and remove loopback devices. */
static grub_err_t
grub_cmd_loopback (grub_extcmd_context_t ctxt, int argc, char **args)
{
struct grub_arg_list *state = ctxt->state;
grub_file_t file;
struct grub_loopback *newdev;
grub_err_t ret;
if (argc < 1)
return grub_error (GRUB_ERR_BAD_ARGUMENT, "device name required");
/* Check if `-d' was used. */
if (state[0].set)
return delete_loopback (args[0]);
if (argc < 2)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
/* Check that a device with requested name does not already exist. */
for (newdev = loopback_list; newdev; newdev = newdev->next)
if (grub_strcmp (newdev->devname, args[0]) == 0)
return grub_error (GRUB_ERR_BAD_ARGUMENT, "device name already exists");
file = grub_file_open (args[1], GRUB_FILE_TYPE_LOOPBACK
| GRUB_FILE_TYPE_NO_DECOMPRESS);
if (! file)
return grub_errno;
/* Unable to replace it, make a new entry. */
newdev = grub_malloc (sizeof (struct grub_loopback));
if (! newdev)
goto fail;
newdev->devname = grub_strdup (args[0]);
if (! newdev->devname)
{
grub_free (newdev);
goto fail;
}
newdev->file = file;
newdev->id = last_id++;
/* Add the new entry to the list. */
newdev->next = loopback_list;
loopback_list = newdev;
return 0;
fail:
ret = grub_errno;
grub_file_close (file);
return ret;
}
static int
grub_loopback_iterate (grub_disk_dev_iterate_hook_t hook, void *hook_data,
grub_disk_pull_t pull)
{
struct grub_loopback *d;
if (pull != GRUB_DISK_PULL_NONE)
return 0;
for (d = loopback_list; d; d = d->next)
{
if (hook (d->devname, hook_data))
return 1;
}
return 0;
}
static grub_err_t
grub_loopback_open (const char *name, grub_disk_t disk)
{
struct grub_loopback *dev;
for (dev = loopback_list; dev; dev = dev->next)
if (grub_strcmp (dev->devname, name) == 0)
break;
if (! dev)
return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "can't open device");
/* Use the filesize for the disk size, round up to a complete sector. */
if (dev->file->size != GRUB_FILE_SIZE_UNKNOWN)
disk->total_sectors = ((dev->file->size + GRUB_DISK_SECTOR_SIZE - 1)
/ GRUB_DISK_SECTOR_SIZE);
else
disk->total_sectors = GRUB_DISK_SIZE_UNKNOWN;
/* Avoid reading more than 512M. */
disk->max_agglomerate = 1 << (29 - GRUB_DISK_SECTOR_BITS
- GRUB_DISK_CACHE_BITS);
disk->id = dev->id;
disk->data = dev;
return 0;
}
static grub_err_t
grub_loopback_read (grub_disk_t disk, grub_disk_addr_t sector,
grub_size_t size, char *buf)
{
grub_file_t file = ((struct grub_loopback *) disk->data)->file;
grub_off_t pos;
grub_file_seek (file, sector << GRUB_DISK_SECTOR_BITS);
grub_file_read (file, buf, size << GRUB_DISK_SECTOR_BITS);
if (grub_errno)
return grub_errno;
/* In case there is more data read than there is available, in case
of files that are not a multiple of GRUB_DISK_SECTOR_SIZE, fill
the rest with zeros. */
pos = (sector + size) << GRUB_DISK_SECTOR_BITS;
if (pos > file->size)
{
grub_size_t amount = pos - file->size;
grub_memset (buf + (size << GRUB_DISK_SECTOR_BITS) - amount, 0, amount);
}
return 0;
}
static grub_err_t
grub_loopback_write (grub_disk_t disk __attribute ((unused)),
grub_disk_addr_t sector __attribute ((unused)),
grub_size_t size __attribute ((unused)),
const char *buf __attribute ((unused)))
{
return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
"loopback write is not supported");
}
static struct grub_disk_dev grub_loopback_dev =
{
.name = "loopback",
.id = GRUB_DISK_DEVICE_LOOPBACK_ID,
.disk_iterate = grub_loopback_iterate,
.disk_open = grub_loopback_open,
.disk_read = grub_loopback_read,
.disk_write = grub_loopback_write,
.next = 0
};
static grub_extcmd_t cmd;
GRUB_MOD_INIT(loopback)
{
cmd = grub_register_extcmd ("loopback", grub_cmd_loopback, 0,
N_("[-d] DEVICENAME FILE."),
/* TRANSLATORS: The file itself is not destroyed
or transformed into drive. */
N_("Make a virtual drive from a file."), options);
grub_disk_dev_register (&grub_loopback_dev);
}
GRUB_MOD_FINI(loopback)
{
grub_unregister_extcmd (cmd);
grub_disk_dev_unregister (&grub_loopback_dev);
}
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