extras/volume_id/volume_id/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 "volume_id.h"
  27 #include "logging.h"
  28 #include "util.h"
  29 #include "linux_swap.h"
  30
  31 struct swap_header_v1_2 {
  32         uint8_t         bootbits[1024];
  33         uint32_t        version;
  34         uint32_t        last_page;
  35         uint32_t        nr_badpages;
  36         uint8_t         uuid[16];
  37         uint8_t         volume_name[16];
  38 } __attribute__((__packed__)) *sw;
  39
  40 #define LARGEST_PAGESIZE                        0x4000
  41
  42 int volume_id_probe_linux_swap(struct volume_id *id, uint64_t off)
  43 {
  44         const uint8_t *buf;
  45         unsigned int page;
  46
  47         dbg("probing at offset 0x%llx", (unsigned long long) off);
  48
  49         /* the swap signature is at the end of the PAGE_SIZE */
  50         for (page = 0x1000; page <= LARGEST_PAGESIZE; page <<= 1) {
  51                         buf = volume_id_get_buffer(id, off + page-10, 10);
  52                         if (buf == NULL)
  53                                 return -1;
  54
  55                         if (memcmp(buf, "SWAP-SPACE", 10) == 0) {
  56                                 strcpy(id->type_version, "1");
  57                                 goto found;
  58                         }
  59
  60                         if (memcmp(buf, "SWAPSPACE2", 10) == 0) {
  61                                 sw = (struct swap_header_v1_2 *) volume_id_get_buffer(id, off, sizeof(struct swap_header_v1_2));
  62                                 if (sw == NULL)
  63                                         return -1;
  64                                 strcpy(id->type_version, "2");
  65                                 volume_id_set_label_raw(id, sw->volume_name, 16);
  66                                 volume_id_set_label_string(id, sw->volume_name, 16);
  67                                 volume_id_set_uuid(id, sw->uuid, UUID_DCE);
  68                                 goto found;
  69                         }
  70         }
  71         return -1;
  72
  73 found:
  74         volume_id_set_usage(id, VOLUME_ID_OTHER);
  75         id->type = "swap";
  76
  77         return 0;
  78 }