filters/partition/partition-gpt.c

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <config.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <stdint.h>
  38 #include <string.h>
  39
  40 #include <nbdkit-filter.h>
  41
  42 #include "byte-swapping.h"
  43 #include "gpt.h"
  44
  45 #include "partition.h"
  46
  47 static void
  48 get_gpt_header (uint8_t *sector,
  49                 uint32_t *nr_partition_entries,
  50                 uint32_t *size_partition_entry)
  51 {
  52   struct gpt_header *header = (struct gpt_header *) sector;
  53   *nr_partition_entries = le32toh (header->nr_partition_entries);
  54   *size_partition_entry = le32toh (header->size_partition_entry);
  55 }
  56
  57 static void
  58 get_gpt_partition (uint8_t *bytes,
  59                    uint8_t *partition_type_guid,
  60                    uint64_t *first_lba, uint64_t *last_lba)
  61 {
  62   struct gpt_entry *entry = (struct gpt_entry *) bytes;
  63   memcpy (partition_type_guid, entry->partition_type_guid, 16);
  64   *first_lba = le64toh (entry->first_lba);
  65   *last_lba = le64toh (entry->last_lba);
  66 }
  67
  68 int
  69 find_gpt_partition (nbdkit_next *next,
  70                     int64_t size, uint8_t *header_bytes,
  71                     int64_t *offset_r, int64_t *range_r)
  72 {
  73   uint8_t partition_bytes[128];
  74   uint32_t nr_partition_entries, size_partition_entry;
  75   uint8_t partition_type_guid[16];
  76   uint64_t first_lba, last_lba;
  77   int i;
  78   int err;
  79
  80   get_gpt_header (header_bytes, &nr_partition_entries, &size_partition_entry);
  81   if (partnum > nr_partition_entries) {
  82     nbdkit_error ("GPT partition number out of range");
  83     return -1;
  84   }
  85
  86   if (size_partition_entry < 128) {
  87     nbdkit_error ("GPT partition entry size is < 128 bytes");
  88     return -1;
  89   }
  90
  91   /* Check the disk is large enough to contain the partition table
  92    * array (twice) plus other GPT overheads.  Otherwise it is likely
  93    * that the GPT header is bogus.
  94    */
  95   if (size < INT64_C (3) * SECTOR_SIZE +
  96       INT64_C (2) * nr_partition_entries * size_partition_entry) {
  97     nbdkit_error ("GPT partition table is too large for this disk");
  98     return -1;
  99   }
 100
 101   for (i = 0; i < nr_partition_entries; ++i) {
 102     /* We already checked these are within bounds above. */
 103     if (next->pread (next, partition_bytes, sizeof partition_bytes,
 104                      2 * SECTOR_SIZE + i * size_partition_entry, 0, &err) == -1)
 105       return -1;
 106     get_gpt_partition (partition_bytes,
 107                        partition_type_guid, &first_lba, &last_lba);
 108     if (memcmp (partition_type_guid,
 109                 "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16) != 0 &&
 110         partnum == i+1) {
 111       *offset_r = first_lba * SECTOR_SIZE;
 112       *range_r = (1 + last_lba - first_lba) * SECTOR_SIZE;
 113       return 0;
 114     }
 115   }
 116
 117   nbdkit_error ("GPT partition %d not found", partnum);
 118   return -1;
 119 }