grub/disk/loopback.c

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/* loopback.c - command to add loopback devices. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2005 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 2 of the License, or
* (at your option) any later version.
*
* This program 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, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <grub/normal.h>
#include <grub/dl.h>
#include <grub/arg.h>
#include <grub/misc.h>
#include <grub/file.h>
#include <grub/disk.h>
#include <grub/mm.h>
struct grub_loopback
{
char *devname;
char *filename;
int has_partitions;
struct grub_loopback *next;
};
static struct grub_loopback *loopback_list;
static const struct grub_arg_option options[] =
{
{"delete", 'd', 0, "Delete the loopback device entry", 0, 0},
{"partitions", 'p', 0, "Set that the drive has partitions to"
" simulate a harddrive", 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))
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_free (dev->filename);
grub_free (dev);
return 0;
}
/* The command to add and remove loopback devices. */
static grub_err_t
grub_cmd_loopback (struct grub_arg_list *state,
int argc, char **args)
{
grub_file_t file;
struct grub_loopback *newdev;
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, "file name required");
file = grub_file_open (args[1]);
if (! file)
return grub_errno;
/* Close the file, the only reason for opening it is validation. */
grub_file_close (file);
/* First try to replace the old device. */
for (newdev = loopback_list; newdev; newdev = newdev->next)
if (!grub_strcmp (newdev->devname, args[0]))
break;
if (newdev)
{
char *newname = grub_strdup (args[1]);
if (!newname)
return grub_errno;
grub_free (newdev->filename);
newdev->filename = newname;
/* Set has_partitions when `--partitions' was used. */
newdev->has_partitions = state[1].set;
return 0;
}
/* Unable to replace it, make a new entry. */
newdev = grub_malloc (sizeof (struct grub_loopback));
if (!newdev)
return grub_errno;
newdev->devname = grub_strdup (args[0]);
if (!newdev->devname)
{
grub_free (newdev);
return grub_errno;
}
newdev->filename = grub_strdup (args[1]);
if (!newdev->devname)
{
grub_free (newdev->devname);
grub_free (newdev);
return grub_errno;
}
/* Set has_partitions when `--partitions' was used. */
newdev->has_partitions = state[1].set;
/* Add the new entry to the list. */
newdev->next = loopback_list;
loopback_list = newdev;
return 0;
}
static int
grub_loopback_iterate (int (*hook) (const char *name))
{
struct grub_loopback *d;
for (d = loopback_list; d; d = d->next)
{
if (hook (d->devname))
return 1;
}
return 0;
}
static grub_err_t
grub_loopback_open (const char *name, grub_disk_t disk)
{
grub_file_t file;
struct grub_loopback *dev;
for (dev = loopback_list; dev; dev = dev->next)
if (!grub_strcmp (dev->devname, name))
break;
if (! dev)
return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "Can't open device");
file = grub_file_open (dev->filename);
if (! file)
return grub_errno;
/* Use the filesize for the disk size, round up to a complete sector. */
disk->total_sectors = ((file->size + GRUB_DISK_SECTOR_SIZE - 1)
/ GRUB_DISK_SECTOR_SIZE);
disk->id = (int) dev;
disk->has_partitions = dev->has_partitions;
disk->data = file;
return 0;
}
static void
grub_loopback_close (grub_disk_t disk)
{
grub_file_t file = (grub_file_t) disk->data;
grub_file_close (file);
}
static grub_err_t
grub_loopback_read (grub_disk_t disk, unsigned long sector,
unsigned long size, char *buf)
{
grub_file_t file = (grub_file_t) disk->data;
long pos;
grub_file_seek (file, sector * GRUB_DISK_SECTOR_SIZE);
grub_file_read (file, buf, size * GRUB_DISK_SECTOR_SIZE);
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 * GRUB_DISK_SECTOR_SIZE + size * GRUB_DISK_SECTOR_SIZE;
if (pos > file->size)
{
unsigned long amount = pos - file->size;
grub_memset (buf + pos - amount, amount, 0);
}
return 0;
}
static grub_err_t
grub_loopback_write (grub_disk_t disk __attribute ((unused)),
unsigned long sector __attribute ((unused)),
unsigned long size __attribute ((unused)),
const char *buf __attribute ((unused)))
{
return GRUB_ERR_NOT_IMPLEMENTED_YET;
}
static struct grub_disk_dev grub_loopback_dev =
{
.name = "loopback",
.id = GRUB_DISK_DEVICE_LOOPBACK_ID,
.iterate = grub_loopback_iterate,
.open = grub_loopback_open,
.close = grub_loopback_close,
.read = grub_loopback_read,
.write = grub_loopback_write,
.next = 0
};
#ifdef GRUB_UTIL
void
grub_loop_init (void)
{
grub_register_command ("loopback", grub_cmd_loopback, GRUB_COMMAND_FLAG_BOTH,
"loopback [OPTIONS] DEVICENAME FILE", "Makes a device of a file", options);
grub_disk_dev_register (&grub_loopback_dev);
}
void
grub_loop_fini (void)
{
grub_unregister_command ("loopback");
grub_disk_dev_unregister (&grub_loopback_dev);
}
#else /* ! GRUB_UTIL */
GRUB_MOD_INIT
{
(void)mod; /* To stop warning. */
grub_register_command ("loopback", grub_cmd_loopback, GRUB_COMMAND_FLAG_BOTH,
"loopback [OPTIONS] DEVICENAME FILE", "Makes a device of a file", options);
grub_disk_dev_register (&grub_loopback_dev);
}
GRUB_MOD_FINI
{
grub_unregister_command ("loopback");
grub_disk_dev_unregister (&grub_loopback_dev);
}
#endif /* ! GRUB_UTIL */