grub-core/partmap/gpt.c

   1 /* gpt.c - Read GUID Partition Tables (GPT).  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2002,2005,2006,2007,2008  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/disk.h>
  21 #include <grub/misc.h>
  22 #include <grub/mm.h>
  23 #include <grub/partition.h>
  24 #include <grub/dl.h>
  25 #include <grub/msdos_partition.h>
  26 #include <grub/gpt_partition.h>
  27
  28 static grub_uint8_t grub_gpt_magic[8] =
  29   {
  30     0x45, 0x46, 0x49, 0x20, 0x50, 0x41, 0x52, 0x54
  31   };
  32
  33 static const grub_gpt_part_type_t grub_gpt_partition_type_empty = GRUB_GPT_PARTITION_TYPE_EMPTY;
  34
  35 /* 512 << 7 = 65536 byte sectors.  */
  36 #define MAX_SECTOR_LOG 7
  37
  38 static struct grub_partition_map grub_gpt_partition_map;
  39
  40 \f
  41
  42 static grub_err_t
  43 gpt_partition_map_iterate (grub_disk_t disk,
  44                            int (*hook) (grub_disk_t disk,
  45                                         const grub_partition_t partition))
  46 {
  47   struct grub_partition part;
  48   struct grub_gpt_header gpt;
  49   struct grub_gpt_partentry entry;
  50   struct grub_msdos_partition_mbr mbr;
  51   grub_uint64_t entries;
  52   unsigned int i;
  53   int last_offset = 0;
  54   int sector_log = 0;
  55
  56   /* Read the protective MBR.  */
  57   if (grub_disk_read (disk, 0, 0, sizeof (mbr), &mbr))
  58     return grub_errno;
  59
  60   /* Check if it is valid.  */
  61   if (mbr.signature != grub_cpu_to_le16 (GRUB_PC_PARTITION_SIGNATURE))
  62     return grub_error (GRUB_ERR_BAD_PART_TABLE, "no signature");
  63
  64   /* Make sure the MBR is a protective MBR and not a normal MBR.  */
  65   if (mbr.entries[0].type != GRUB_PC_PARTITION_TYPE_GPT_DISK)
  66     return grub_error (GRUB_ERR_BAD_PART_TABLE, "no GPT partition map found");
  67
  68   /* Read the GPT header.  */
  69   for (sector_log = 0; sector_log < MAX_SECTOR_LOG; sector_log++)
  70     {
  71       if (grub_disk_read (disk, 1 << sector_log, 0, sizeof (gpt), &gpt))
  72         return grub_errno;
  73
  74       if (grub_memcmp (gpt.magic, grub_gpt_magic, sizeof (grub_gpt_magic)) == 0)
  75         break;
  76     }
  77   if (sector_log == MAX_SECTOR_LOG)
  78     return grub_error (GRUB_ERR_BAD_PART_TABLE, "no valid GPT header");
  79
  80   grub_dprintf ("gpt", "Read a valid GPT header\n");
  81
  82   entries = grub_le_to_cpu64 (gpt.partitions) << sector_log;
  83   for (i = 0; i < grub_le_to_cpu32 (gpt.maxpart); i++)
  84     {
  85       if (grub_disk_read (disk, entries, last_offset,
  86                           sizeof (entry), &entry))
  87         return grub_errno;
  88
  89       if (grub_memcmp (&grub_gpt_partition_type_empty, &entry.type,
  90                        sizeof (grub_gpt_partition_type_empty)))
  91         {
  92           /* Calculate the first block and the size of the partition.  */
  93           part.start = grub_le_to_cpu64 (entry.start) << sector_log;
  94           part.len = (grub_le_to_cpu64 (entry.end)
  95                       - grub_le_to_cpu64 (entry.start) + 1)  << sector_log;
  96           part.offset = entries;
  97           part.number = i;
  98           part.index = last_offset;
  99           part.partmap = &grub_gpt_partition_map;
 100
 101           grub_dprintf ("gpt", "GPT entry %d: start=%lld, length=%lld\n", i,
 102                         (unsigned long long) part.start,
 103                         (unsigned long long) part.len);
 104
 105           if (hook (disk, &part))
 106             return grub_errno;
 107         }
 108
 109       last_offset += grub_le_to_cpu32 (gpt.partentry_size);
 110       if (last_offset == GRUB_DISK_SECTOR_SIZE)
 111         {
 112           last_offset = 0;
 113           entries++;
 114         }
 115     }
 116
 117   return GRUB_ERR_NONE;
 118 }
 119
 120 \f
 121 /* Partition map type.  */
 122 static struct grub_partition_map grub_gpt_partition_map =
 123   {
 124     .name = "gpt",
 125     .iterate = gpt_partition_map_iterate,
 126   };
 127
 128 GRUB_MOD_INIT(part_gpt)
 129 {
 130   grub_partition_map_register (&grub_gpt_partition_map);
 131 }
 132
 133 GRUB_MOD_FINI(part_gpt)
 134 {
 135   grub_partition_map_unregister (&grub_gpt_partition_map);
 136 }