busybox/util-linux/volume_id/nilfs.c

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/*
* volume_id - reads filesystem label and uuid
*
* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2012 S-G Bergh <sgb@systemasis.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
//kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_NILFS) += nilfs.o
//config:config FEATURE_VOLUMEID_NILFS
//config: bool "nilfs filesystem"
//config: default y
//config: depends on VOLUMEID
//config: help
//config: NILFS is a New Implementation of a Log-Structured File System (LFS)
//config: that supports continuous snapshots. This provides features like
//config: versioning of the entire filesystem, restoration of files that
//config: were deleted a few minutes ago. NILFS keeps consistency like
//config: conventional LFS, so it provides quick recovery after system crashes.
//config:
//config: The possible use of NILFS includes versioning, tamper detection,
//config: SOX compliance logging, and so forth. It can serve as an alternative
//config: filesystem for Linux desktop environment, or as a basis of advanced
//config: storage appliances.
#include "volume_id_internal.h"
#define NILFS_UUID_SIZE 16
#define NILFS_LABEL_SIZE 80
#define NILFS_SB1_OFFSET 0x400
#define NILFS_SB2_OFFSET 0x1000
#define NILFS_MAGIC 0x3434
struct nilfs2_super_block {
/* 0x00 */ uint32_t s_rev_level; // Major revision level.
/* 0x04 */ uint16_t s_minor_rev_level; // Minor revision level.
/* 0x06 */ uint16_t s_magic; // Magic signature.
/* 0x08 */ uint16_t s_bytes;
/* 0x0A */ uint16_t s_flags;
/* 0x0C */ uint32_t s_crc_seed;
/* 0x10 */ uint32_t s_sum;
/* 0x14 */ uint32_t s_log_block_size;
/* 0x18 */ uint64_t s_nsegments;
/* 0x20 */ uint64_t s_dev_size; // Block device size in bytes.
/* 0x28 */ uint64_t s_first_data_block;
/* 0x30 */ uint32_t s_blocks_per_segment;
/* 0x34 */ uint32_t s_r_segments_percentage;
/* 0x38 */ uint64_t s_last_cno;
/* 0x40 */ uint64_t s_last_pseg;
/* 0x48 */ uint64_t s_last_seq;
/* 0x50 */ uint64_t s_free_blocks_count;
/* 0x58 */ uint64_t s_ctime;
/* 0x60 */ uint64_t s_mtime;
/* 0x68 */ uint64_t s_wtime;
/* 0x70 */ uint16_t s_mnt_count;
/* 0x72 */ uint16_t s_max_mnt_count;
/* 0x74 */ uint16_t s_state;
/* 0x76 */ uint16_t s_errors;
/* 0x78 */ uint64_t s_lastcheck;
/* 0x80 */ uint32_t s_checkinterval;
/* 0x84 */ uint32_t s_creator_os;
/* 0x88 */ uint16_t s_def_resuid;
/* 0x8A */ uint16_t s_def_resgid;
/* 0x8C */ uint32_t s_first_ino;
/* 0x90 */ uint16_t s_inode_size;
/* 0x92 */ uint16_t s_dat_entry_size;
/* 0x94 */ uint16_t s_checkpoint_size;
/* 0x96 */ uint16_t s_segment_usage_size;
/* 0x98 */ uint8_t s_uuid[NILFS_UUID_SIZE]; // 128-bit UUID for volume.
/* 0xA8 */ uint8_t s_volume_name[NILFS_LABEL_SIZE]; // Volume label.
/* 0xF8 */ // ...
} PACKED;
int FAST_FUNC volume_id_probe_nilfs(struct volume_id *id /*,uint64_t off*/)
{
struct nilfs2_super_block *sb;
// Primary super block
dbg("nilfs: probing at offset 0x%x", NILFS_SB1_OFFSET);
sb = volume_id_get_buffer(id, NILFS_SB1_OFFSET, sizeof(*sb));
if (sb == NULL)
return -1;
if (sb->s_magic != NILFS_MAGIC)
return -1;
// The secondary superblock is not always used, so ignore it for now.
// When used it is at 4K from the end of the partition (sb->s_dev_size - NILFS_SB2_OFFSET).
volume_id_set_label_string(id, sb->s_volume_name, NILFS_LABEL_SIZE < VOLUME_ID_LABEL_SIZE ?
NILFS_LABEL_SIZE : VOLUME_ID_LABEL_SIZE);
volume_id_set_uuid(id, sb->s_uuid, UUID_DCE);
if (sb->s_rev_level == 2)
IF_FEATURE_BLKID_TYPE(id->type = "nilfs2");
return 0;
}