LXR busybox/util-linux/volume

   1/*
   2 * volume_id - reads filesystem label and uuid
   3 *
   4 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
   5 * Copyright (C) 2012 S-G Bergh <sgb@systemasis.org>
   6 *
   7 *      This library is free software; you can redistribute it and/or
   8 *      modify it under the terms of the GNU Lesser General Public
   9 *      License as published by the Free Software Foundation; either
  10 *      version 2.1 of the License, or (at your option) any later version.
  11 *
  12 *      This library is distributed in the hope that it will be useful,
  13 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15 *      Lesser General Public License for more details.
  16 *
  17 *      You should have received a copy of the GNU Lesser General Public
  18 *      License along with this library; if not, write to the Free Software
  19 *      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20 */
  21//config:config FEATURE_VOLUMEID_NILFS
  22//config:       bool "nilfs filesystem"
  23//config:       default y
  24//config:       depends on VOLUMEID
  25//config:       help
  26//config:       NILFS is a New Implementation of a Log-Structured File System (LFS)
  27//config:       that supports continuous snapshots. This provides features like
  28//config:       versioning of the entire filesystem, restoration of files that
  29//config:       were deleted a few minutes ago. NILFS keeps consistency like
  30//config:       conventional LFS, so it provides quick recovery after system crashes.
  31//config:
  32//config:       The possible use of NILFS includes versioning, tamper detection,
  33//config:       SOX compliance logging, and so forth. It can serve as an alternative
  34//config:       filesystem for Linux desktop environment, or as a basis of advanced
  35//config:       storage appliances.
  36
  37//kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_NILFS) += nilfs.o
  38
  39#include "volume_id_internal.h"
  40
  41#define NILFS_UUID_SIZE 16
  42#define NILFS_LABEL_SIZE 80
  43#define NILFS_SB1_OFFSET 0x400
  44#define NILFS_SB2_OFFSET 0x1000
  45#define NILFS_MAGIC 0x3434
  46
  47struct nilfs2_super_block {
  48/* 0x00 */      uint32_t s_rev_level;                           // Major revision level.
  49/* 0x04 */      uint16_t s_minor_rev_level;                     // Minor revision level.
  50/* 0x06 */      uint16_t s_magic;                               // Magic signature.
  51/* 0x08 */      uint16_t s_bytes;
  52/* 0x0A */      uint16_t s_flags;
  53/* 0x0C */      uint32_t s_crc_seed;
  54/* 0x10 */      uint32_t s_sum;
  55/* 0x14 */      uint32_t s_log_block_size;
  56/* 0x18 */      uint64_t s_nsegments;
  57/* 0x20 */      uint64_t s_dev_size;                            // Block device size in bytes.
  58/* 0x28 */      uint64_t s_first_data_block;
  59/* 0x30 */      uint32_t s_blocks_per_segment;
  60/* 0x34 */      uint32_t s_r_segments_percentage;
  61/* 0x38 */      uint64_t s_last_cno;
  62/* 0x40 */      uint64_t s_last_pseg;
  63/* 0x48 */      uint64_t s_last_seq;
  64/* 0x50 */      uint64_t s_free_blocks_count;
  65/* 0x58 */      uint64_t s_ctime;
  66/* 0x60 */      uint64_t s_mtime;
  67/* 0x68 */      uint64_t s_wtime;
  68/* 0x70 */      uint16_t s_mnt_count;
  69/* 0x72 */      uint16_t s_max_mnt_count;
  70/* 0x74 */      uint16_t s_state;
  71/* 0x76 */      uint16_t s_errors;
  72/* 0x78 */      uint64_t s_lastcheck;
  73/* 0x80 */      uint32_t s_checkinterval;
  74/* 0x84 */      uint32_t s_creator_os;
  75/* 0x88 */      uint16_t s_def_resuid;
  76/* 0x8A */      uint16_t s_def_resgid;
  77/* 0x8C */      uint32_t s_first_ino;
  78/* 0x90 */      uint16_t s_inode_size;
  79/* 0x92 */      uint16_t s_dat_entry_size;
  80/* 0x94 */      uint16_t s_checkpoint_size;
  81/* 0x96 */      uint16_t s_segment_usage_size;
  82/* 0x98 */      uint8_t s_uuid[NILFS_UUID_SIZE];                // 128-bit UUID for volume.
  83/* 0xA8 */      uint8_t s_volume_name[NILFS_LABEL_SIZE];        // Volume label.
  84/* 0xF8 */      // ...
  85} PACKED;
  86
  87int FAST_FUNC volume_id_probe_nilfs(struct volume_id *id /*,uint64_t off*/)
  88{
  89        struct nilfs2_super_block *sb;
  90
  91        // Primary super block
  92        dbg("nilfs: probing at offset 0x%x", NILFS_SB1_OFFSET);
  93
  94        sb = volume_id_get_buffer(id, NILFS_SB1_OFFSET, sizeof(*sb));
  95
  96        if (sb == NULL)
  97                return -1;
  98
  99        if (sb->s_magic != NILFS_MAGIC)
 100                return -1;
 101
 102        // The secondary superblock is not always used, so ignore it for now.
 103        // When used it is at 4K from the end of the partition (sb->s_dev_size - NILFS_SB2_OFFSET).
 104
 105        volume_id_set_label_string(id, sb->s_volume_name, NILFS_LABEL_SIZE < VOLUME_ID_LABEL_SIZE ?
 106                                NILFS_LABEL_SIZE : VOLUME_ID_LABEL_SIZE);
 107        volume_id_set_uuid(id, sb->s_uuid, UUID_DCE);
 108
 109        if (sb->s_rev_level == 2)
 110                IF_FEATURE_BLKID_TYPE(id->type = "nilfs2");
 111
 112        return 0;
 113}
 114