extras/volume_id/volume_id/linux_swap/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 library is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU Lesser General Public
   8  *      License as published by the Free Software Foundation; either
   9  *      version 2.1 of the License, or (at your option) any later version.
  10  *
  11  *      This library 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 GNU
  14  *      Lesser General Public License for more details.
  15  *
  16  *      You should have received a copy of the GNU Lesser General Public
  17  *      License along with this library; if not, write to the Free Software
  18  *      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  19  */
  20
  21 #ifndef _GNU_SOURCE
  22 #define _GNU_SOURCE 1
  23 #endif
  24
  25 #ifdef HAVE_CONFIG_H
  26 #  include <config.h>
  27 #endif
  28
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <unistd.h>
  32 #include <string.h>
  33 #include <errno.h>
  34 #include <ctype.h>
  35 #include <asm/types.h>
  36
  37 #include "../volume_id.h"
  38 #include "../logging.h"
  39 #include "../util.h"
  40 #include "linux_swap.h"
  41
  42 #define LARGEST_PAGESIZE                        0x4000
  43
  44 int volume_id_probe_linux_swap(struct volume_id *id, __u64 off)
  45 {
  46         struct swap_header_v1_2 {
  47                 __u8    bootbits[1024];
  48                 __u32   version;
  49                 __u32   last_page;
  50                 __u32   nr_badpages;
  51                 __u8    uuid[16];
  52                 __u8    volume_name[16];
  53         } __attribute__((__packed__)) *sw;
  54
  55         const __u8 *buf;
  56         unsigned int page;
  57
  58         /* the swap signature is at the end of the PAGE_SIZE */
  59         for (page = 0x1000; page <= LARGEST_PAGESIZE; page <<= 1) {
  60                         buf = volume_id_get_buffer(id, off + page-10, 10);
  61                         if (buf == NULL)
  62                                 return -1;
  63
  64                         if (memcmp(buf, "SWAP-SPACE", 10) == 0) {
  65                                 strcpy(id->type_version, "1");
  66                                 goto found;
  67                         }
  68
  69                         if (memcmp(buf, "SWAPSPACE2", 10) == 0) {
  70                                 sw = (struct swap_header_v1_2 *) volume_id_get_buffer(id, off, sizeof(struct swap_header_v1_2));
  71                                 if (sw == NULL)
  72                                         return -1;
  73                                 strcpy(id->type_version, "2");
  74                                 volume_id_set_label_raw(id, sw->volume_name, 16);
  75                                 volume_id_set_label_string(id, sw->volume_name, 16);
  76                                 volume_id_set_uuid(id, sw->uuid, UUID_DCE);
  77                                 goto found;
  78                         }
  79         }
  80         return -1;
  81
  82 found:
  83         volume_id_set_usage(id, VOLUME_ID_OTHER);
  84         id->type = "swap";
  85
  86         return 0;
  87 }