Edit

thodg/ext4fs/include

Branch :

  • ext4fs.h 
  • /* kc3
 * Copyright 2025 kmx.io <contact@kmx.io>
 *
 * Permission is hereby granted to use this software granted the above
 * copyright notice and this permission paragraph are included in all
 * copies and substantial portions of this software.
 *
 * THIS SOFTWARE IS PROVIDED "AS-IS" WITHOUT ANY GUARANTEE OF
 * PURPOSE AND PERFORMANCE. IN NO EVENT WHATSOEVER SHALL THE
 * AUTHOR BE CONSIDERED LIABLE FOR THE USE AND PERFORMANCE OF
 * THIS SOFTWARE.
 */
#ifndef EXT4FS_H
#define EXT4FS_H

#include <stdint.h>

#define EXT4FS_DYNAMIC_REV 1
#define EXT4FS_DYNAMIC_REV_MINOR 0
#define EXT4FS_FEATURE_INCOMPAT_EXTENTS 0x00000040
#define EXT4FS_FEATURE_RO_COMPAT_SPARSE_SUPER 0x0001
#define EXT4FS_MAGIC 0xEF53
#define EXT4FS_SUPER_BLOCK_OFFSET 1024
#define EXT4FS_SUPER_BLOCK_SIZE 1024
#define EXT4FS_VALID_FS 1

#define EXT4FS_OS_LINUX     0
#define EXT4FS_OS_HURD      1
#define EXT4FS_OS_MASIX     2
#define EXT4FS_OS_FREEBSD   3
#define EXT4FS_OS_LITES     4
#define EXT4FS_OS_OPENBSD   5

struct ext4fs_super_block {
    uint32_t sb_inodes_count;         // Total number of inodes
    uint32_t sb_blocks_count_lo;      // Total number of blocks (low 32 bits)
    uint32_t sb_r_blocks_count_lo;    // Reserved blocks count
    uint32_t sb_free_blocks_count_lo; // Free blocks count
    uint32_t sb_free_inodes_count;    // Free inodes count
    uint32_t sb_first_data_block;     // First data block (1 for blocksize > 1k)
    uint32_t sb_log_block_size;       // log2(block size) - 10
    uint32_t sb_log_cluster_size;     // log2(cluster size) - 10
    uint32_t sb_blocks_per_group;     // Number of blocks per group
    uint32_t sb_clusters_per_group;   // Clusters per group
    uint32_t sb_inodes_per_group;     // Inodes per group
    uint32_t sb_mtime;                // Mount time
    uint32_t sb_wtime;                // Write time
    uint16_t sb_mnt_count;            // Mount count
    uint16_t sb_max_mnt_count;        // Max mount count before fsck
    uint16_t sb_magic;                // Magic signature
    uint16_t sb_state;                // File system state
    uint16_t sb_errors;               // Behaviour when detecting errors
    uint16_t sb_minor_rev_level;      // Minor revision level
    uint32_t sb_lastcheck;            // Last check time
    uint32_t sb_checkinterval;        // Max time between checks
    uint32_t sb_creator_os;           // OS
    uint32_t sb_rev_level;            // Revision level
    uint16_t sb_def_resuid;           // Default uid for reserved blocks
    uint16_t sb_def_resgid;           // Default gid for reserved blocks

    // EXT4_DYNAMIC_REV Specific:
    uint32_t sb_first_ino;            // First non-reserved inode
    uint16_t sb_inode_size;           // Inode size
    uint16_t sb_block_group_nr;       // Block group # of this superblock
    uint32_t sb_feature_compat;       // Compatible feature set
    uint32_t sb_feature_incompat;     // Incompatible feature set
    uint32_t sb_feature_ro_compat;    // Read-only compatible feature set
    uint8_t  sb_uuid[16];             // 128-bit filesystem UUID
    char     sb_volume_name[16];      // Volume name
    char     sb_last_mounted[64];     // Directory where last mounted
    uint32_t sb_algorithm_usage_bitmap; // For compression (unused)

    // Journaling support:
    uint8_t  sb_journal_uuid[16];     // UUID of journal superblock
    uint32_t sb_journal_inum;         // Inode number of journal file
    uint32_t sb_journal_dev;          // Device number of journal file
    uint32_t sb_last_orphan;          // Start of orphan inode list

    uint32_t sb_hash_seed[4];         // HTREE hash seed
    uint8_t  sb_def_hash_version;     // Default hash version
    uint8_t  sb_jnl_backup_type;
    uint16_t sb_desc_size;            // Group descriptor size
    uint32_t sb_default_mount_opts;
    uint32_t sb_first_meta_bg;        // First metablock block group
    uint32_t sb_mkfs_time;            // When the FS was created
    uint32_t sb_jnl_blocks[17];       // Backup of journal inode

    // 64-bit support:
    uint32_t sb_blocks_count_hi;
    uint32_t sb_r_blocks_count_hi;
    uint32_t sb_free_blocks_count_hi;
    uint16_t sb_min_extra_isize;
    uint16_t sb_want_extra_isize;
    uint32_t sb_flags;
    uint16_t sb_raid_stride;
    uint16_t sb_mmp_interval;
    uint64_t sb_mmp_block;
    uint32_t sb_raid_stripe_width;
    uint8_t  sb_log_groups_per_flex;
    uint8_t  sb_checksum_type;
    uint16_t sb_reserved_pad;
    uint64_t sb_kbytes_written;
    uint32_t sb_snapshot_inum;
    uint32_t sb_snapshot_id;
    uint64_t sb_snapshot_r_blocks_count;
    uint32_t sb_snapshot_list;

    // Error handling:
    uint32_t sb_error_count;
    uint32_t sb_first_error_time;
    uint32_t sb_first_error_ino;
    uint64_t sb_first_error_block;
    uint8_t  sb_first_error_func[32];
    uint32_t sb_first_error_line;
    uint32_t sb_last_error_time;
    uint32_t sb_last_error_ino;
    uint32_t sb_last_error_line;
    uint64_t sb_last_error_block;
    uint8_t  sb_last_error_func[32];

    uint8_t  sb_mount_opts[64];
    uint32_t sb_usr_quota_inum;
    uint32_t sb_grp_quota_inum;
    uint32_t sb_overhead_blocks;
    uint32_t sb_backup_bgs[2];
    uint8_t  sb_encrypt_algos[4];
    uint8_t  sb_encrypt_pw_salt[16];
    uint32_t sb_lpf_ino;
    uint32_t sb_prj_quota_inum;
    uint32_t sb_checksum_seed;

    uint8_t  sb_wtime_hi;
    uint8_t  sb_mtime_hi;
    uint8_t  sb_mkfs_time_hi;
    uint8_t  sb_lastcheck_hi;
    uint8_t  sb_first_error_time_hi;
    uint8_t  sb_last_error_time_hi;
    uint8_t  sb_pad[2];
    uint32_t sb_reserved[96];

    uint32_t sb_checksum;             // Superblock checksum
} __attribute__((packed));

struct ext4fs_group_desc {
    uint32_t gd_block_bitmap_lo;   // Block ID of block bitmap
    uint32_t gd_inode_bitmap_lo;   // Block ID of inode bitmap
    uint32_t gd_inode_table_lo;    // Starting block of inode table
    uint16_t gd_free_blocks_count; // Free blocks in this group
    uint16_t gd_free_inodes_count; // Free inodes in this group
    uint16_t gd_used_dirs_count;   // Number of directories in this group
    uint16_t gd_flags;
    uint32_t gd_exclude_bitmap_lo; // Optional (sparse allocation)
    uint16_t gd_block_bitmap_csum;
    uint16_t gd_inode_bitmap_csum;
    uint16_t gd_itable_unused;
    uint16_t gd_checksum;
    // The rest is for 64-bit addressing (optional):
    uint32_t gd_block_bitmap_hi;
    uint32_t gd_inode_bitmap_hi;
    uint32_t gd_inode_table_hi;
    uint16_t gd_free_blocks_count_hi;
    uint16_t gd_free_inodes_count_hi;
    uint16_t gd_used_dirs_count_hi;
    uint16_t gd_itable_unused_hi;
    uint32_t gd_exclude_bitmap_hi;
    uint16_t gd_block_bitmap_csum_hi;
    uint16_t gd_inode_bitmap_csum_hi;
    uint32_t gd_reserved;
} __attribute__((packed));

#endif /* EXT4FS_H */