152 lines
4.1 KiB
C
152 lines
4.1 KiB
C
/* pc.c - Read PC style partition tables. */
|
||
/*
|
||
* GRUB -- GRand Unified Bootloader
|
||
* Copyright (C) 2002,2004,2005,2006,2007,2008,2009 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/partition.h>
|
||
#include <grub/msdos_partition.h>
|
||
#include <grub/disk.h>
|
||
#include <grub/mm.h>
|
||
#include <grub/misc.h>
|
||
#include <grub/dl.h>
|
||
|
||
static struct grub_partition_map grub_msdos_partition_map;
|
||
|
||
|
||
static grub_err_t
|
||
pc_partition_map_iterate (grub_disk_t disk,
|
||
int (*hook) (grub_disk_t disk,
|
||
const grub_partition_t partition))
|
||
{
|
||
struct grub_partition p;
|
||
struct grub_msdos_partition_mbr mbr;
|
||
int labeln = 0;
|
||
grub_disk_addr_t lastaddr;
|
||
grub_disk_addr_t ext_offset;
|
||
|
||
p.offset = 0;
|
||
ext_offset = 0;
|
||
p.number = -1;
|
||
p.partmap = &grub_msdos_partition_map;
|
||
|
||
/* Any value different than `p.offset' will satisfy the check during
|
||
first loop. */
|
||
lastaddr = !p.offset;
|
||
|
||
while (1)
|
||
{
|
||
int i;
|
||
struct grub_msdos_partition_entry *e;
|
||
|
||
/* Read the MBR. */
|
||
if (grub_disk_read (disk, p.offset, 0, sizeof (mbr), &mbr))
|
||
goto finish;
|
||
|
||
/* This is our loop-detection algorithm. It works the following way:
|
||
It saves last position which was a power of two. Then it compares the
|
||
saved value with a current one. This way it's guaranteed that the loop
|
||
will be broken by at most third walk.
|
||
*/
|
||
if (labeln && lastaddr == p.offset)
|
||
return grub_error (GRUB_ERR_BAD_PART_TABLE, "loop detected");
|
||
|
||
labeln++;
|
||
if ((labeln & (labeln - 1)) == 0)
|
||
lastaddr = p.offset;
|
||
|
||
/* Check if it is valid. */
|
||
if (mbr.signature != grub_cpu_to_le16 (GRUB_PC_PARTITION_SIGNATURE))
|
||
return grub_error (GRUB_ERR_BAD_PART_TABLE, "no signature");
|
||
|
||
for (i = 0; i < 4; i++)
|
||
if (mbr.entries[i].flag & 0x7f)
|
||
return grub_error (GRUB_ERR_BAD_PART_TABLE, "bad boot flag");
|
||
|
||
/* Analyze DOS partitions. */
|
||
for (p.index = 0; p.index < 4; p.index++)
|
||
{
|
||
e = mbr.entries + p.index;
|
||
|
||
p.start = p.offset + grub_le_to_cpu32 (e->start);
|
||
p.len = grub_le_to_cpu32 (e->length);
|
||
|
||
grub_dprintf ("partition",
|
||
"partition %d: flag 0x%x, type 0x%x, start 0x%llx, len 0x%llx\n",
|
||
p.index, e->flag, e->type,
|
||
(unsigned long long) p.start,
|
||
(unsigned long long) p.len);
|
||
|
||
/* If this is a GPT partition, this MBR is just a dummy. */
|
||
if (e->type == GRUB_PC_PARTITION_TYPE_GPT_DISK && p.index == 0)
|
||
return grub_error (GRUB_ERR_BAD_PART_TABLE, "dummy mbr");
|
||
|
||
/* If this partition is a normal one, call the hook. */
|
||
if (! grub_msdos_partition_is_empty (e->type)
|
||
&& ! grub_msdos_partition_is_extended (e->type))
|
||
{
|
||
p.number++;
|
||
|
||
if (hook (disk, &p))
|
||
return grub_errno;
|
||
}
|
||
else if (p.number < 4)
|
||
/* If this partition is a logical one, shouldn't increase the
|
||
partition number. */
|
||
p.number++;
|
||
}
|
||
|
||
/* Find an extended partition. */
|
||
for (i = 0; i < 4; i++)
|
||
{
|
||
e = mbr.entries + i;
|
||
|
||
if (grub_msdos_partition_is_extended (e->type))
|
||
{
|
||
p.offset = ext_offset + grub_le_to_cpu32 (e->start);
|
||
if (! ext_offset)
|
||
ext_offset = p.offset;
|
||
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* If no extended partition, the end. */
|
||
if (i == 4)
|
||
break;
|
||
}
|
||
|
||
finish:
|
||
return grub_errno;
|
||
}
|
||
|
||
|
||
/* Partition map type. */
|
||
static struct grub_partition_map grub_msdos_partition_map =
|
||
{
|
||
.name = "msdos",
|
||
.iterate = pc_partition_map_iterate,
|
||
};
|
||
|
||
GRUB_MOD_INIT(part_msdos)
|
||
{
|
||
grub_partition_map_register (&grub_msdos_partition_map);
|
||
}
|
||
|
||
GRUB_MOD_FINI(part_msdos)
|
||
{
|
||
grub_partition_map_unregister (&grub_msdos_partition_map);
|
||
}
|