extras/volume_id/lib/linux_swap.c

   1 /*
   2  * volume_id - reads filesystem label and uuid
   3  *
   4  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
   5  *
   6  *      This program is free software; you can redistribute it and/or modify it
   7  *      under the terms of the GNU General Public License as published by the
   8  *      Free Software Foundation version 2 of the License.
   9  */
  10
  11 #ifndef _GNU_SOURCE
  12 #define _GNU_SOURCE 1
  13 #endif
  14
  15 #ifdef HAVE_CONFIG_H
  16 #  include <config.h>
  17 #endif
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <string.h>
  23 #include <errno.h>
  24 #include <ctype.h>
  25
  26 #include "libvolume_id.h"
  27 #include "util.h"
  28
  29 struct swap_header_v1_2 {
  30         uint8_t         bootbits[1024];
  31         uint32_t        version;
  32         uint32_t        last_page;
  33         uint32_t        nr_badpages;
  34         uint8_t         uuid[16];
  35         uint8_t         volume_name[16];
  36 } PACKED *sw;
  37
  38 #define LARGEST_PAGESIZE                        0x4000
  39
  40 int volume_id_probe_linux_swap(struct volume_id *id, uint64_t off)
  41 {
  42         const uint8_t *buf;
  43         unsigned int page;
  44
  45         dbg("probing at offset 0x%llx", (unsigned long long) off);
  46
  47         /* the swap signature is at the end of the PAGE_SIZE */
  48         for (page = 0x1000; page <= LARGEST_PAGESIZE; page <<= 1) {
  49                         buf = volume_id_get_buffer(id, off + page-10, 10);
  50                         if (buf == NULL)
  51                                 return -1;
  52
  53                         if (memcmp(buf, "SWAP-SPACE", 10) == 0) {
  54                                 strcpy(id->type_version, "1");
  55                                 goto found;
  56                         }
  57
  58                         if (memcmp(buf, "SWAPSPACE2", 10) == 0) {
  59                                 sw = (struct swap_header_v1_2 *) volume_id_get_buffer(id, off, sizeof(struct swap_header_v1_2));
  60                                 if (sw == NULL)
  61                                         return -1;
  62                                 strcpy(id->type_version, "2");
  63                                 volume_id_set_label_raw(id, sw->volume_name, 16);
  64                                 volume_id_set_label_string(id, sw->volume_name, 16);
  65                                 volume_id_set_uuid(id, sw->uuid, UUID_DCE);
  66                                 goto found;
  67                         }
  68         }
  69         return -1;
  70
  71 found:
  72         volume_id_set_usage(id, VOLUME_ID_OTHER);
  73         id->type = "swap";
  74
  75         return 0;
  76 }