partmap/pc.c

   1 /* pc.c - Read PC style partition tables.  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2002,2004,2005,2006,2007,2008,2009  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/partition.h>
  21 #include <grub/pc_partition.h>
  22 #include <grub/disk.h>
  23 #include <grub/mm.h>
  24 #include <grub/misc.h>
  25 #include <grub/dl.h>
  26
  27 static struct grub_partition_map grub_pc_partition_map;
  28 \f
  29
  30 static grub_err_t
  31 pc_partition_map_iterate (grub_disk_t disk,
  32                           int (*hook) (grub_disk_t disk,
  33                                        const grub_partition_t partition))
  34 {
  35   struct grub_partition p;
  36   struct grub_pc_partition *pcdata;
  37   struct grub_pc_partition_mbr mbr;
  38
  39   pcdata = grub_malloc (sizeof (*pcdata));
  40   p.offset = 0;
  41   pcdata->ext_offset = 0;
  42   p.data = pcdata;
  43   p.number = -1;
  44   p.partmap = &grub_pc_partition_map;
  45
  46   /* Signature check is known to cause false positives
  47      because the same signature is used for bootsectors.  */
  48   if (disk->partition)
  49     {
  50       grub_free (pcdata);
  51       return grub_error (GRUB_ERR_BAD_PART_TABLE,
  52                          "pc partition can't be nested");
  53     }
  54
  55   while (1)
  56     {
  57       int i;
  58       struct grub_pc_partition_entry *e;
  59
  60       /* Read the MBR.  */
  61       if (grub_disk_read (disk, p.offset, 0, sizeof (mbr), &mbr))
  62         goto finish;
  63
  64       /* Check if it is valid.  */
  65       if (mbr.signature != grub_cpu_to_le16 (GRUB_PC_PARTITION_SIGNATURE))
  66         {
  67           grub_free (pcdata);
  68           return grub_error (GRUB_ERR_BAD_PART_TABLE, "no signature");
  69         }
  70
  71       /* Analyze DOS partitions.  */
  72       for (pcdata->index = 0; pcdata->index < 4; pcdata->index++)
  73         {
  74           e = mbr.entries + pcdata->index;
  75
  76           p.start = p.offset + grub_le_to_cpu32 (e->start);
  77           p.len = grub_le_to_cpu32 (e->length);
  78           pcdata->dos_type = e->type;
  79
  80           grub_dprintf ("partition",
  81                         "partition %d: flag 0x%x, type 0x%x, start 0x%llx, len 0x%llx\n",
  82                         pcdata->index, e->flag, pcdata->dos_type,
  83                         (unsigned long long) p.start,
  84                         (unsigned long long) p.len);
  85
  86           /* If this is a GPT partition, this MBR is just a dummy.  */
  87           if (e->type == GRUB_PC_PARTITION_TYPE_GPT_DISK && pcdata->index == 0)
  88             {
  89               grub_free (pcdata);
  90               return grub_error (GRUB_ERR_BAD_PART_TABLE, "dummy mbr");
  91             }
  92
  93           /* If this partition is a normal one, call the hook.  */
  94           if (! grub_pc_partition_is_empty (e->type)
  95               && ! grub_pc_partition_is_extended (e->type))
  96             {
  97               p.number++;
  98
  99               if (hook (disk, &p))
 100                 return 1;
 101             }
 102           else if (p.number < 4)
 103             /* If this partition is a logical one, shouldn't increase the
 104                partition number.  */
 105             p.number++;
 106         }
 107
 108       /* Find an extended partition.  */
 109       for (i = 0; i < 4; i++)
 110         {
 111           e = mbr.entries + i;
 112
 113           if (grub_pc_partition_is_extended (e->type))
 114             {
 115               p.offset = pcdata->ext_offset + grub_le_to_cpu32 (e->start);
 116               if (! pcdata->ext_offset)
 117                 pcdata->ext_offset = p.offset;
 118
 119               break;
 120             }
 121         }
 122
 123       /* If no extended partition, the end.  */
 124       if (i == 4)
 125         break;
 126     }
 127
 128  finish:
 129   grub_free (pcdata);
 130   return grub_errno;
 131 }
 132
 133 \f
 134 /* Partition map type.  */
 135 static struct grub_partition_map grub_pc_partition_map =
 136   {
 137     .name = "pc_partition_map",
 138     .iterate = pc_partition_map_iterate,
 139   };
 140
 141 GRUB_MOD_INIT(pc_partition_map)
 142 {
 143   grub_partition_map_register (&grub_pc_partition_map);
 144 }
 145
 146 GRUB_MOD_FINI(pc_partition_map)
 147 {
 148   grub_partition_map_unregister (&grub_pc_partition_map);
 149 }