Apple File System Reference

Description

Apple File System is the default file format used on Apple platforms. Apple File System is the successor to HFS Plus, so some aspects of its design intentionally follow HFS Plus to enable data migration from HFS Plus to Apple File System. Other aspects of its design address limitations with HFS Plus and enable features such as cloning files, snapshots, encryption, and sharing free space between volumes. Most apps interact with the file system using high-level interfaces provided by Foundation, which means most de- velopers donʼt need to read this document. This document is for developers of software that interacts with the file system directly, without using any frameworks or the operating system—for example, a disk recovery utility or an im- plementation of Apple File System on another platform. The on-disk data structures described in this document make up the file system; software that interacts with them defines corresponding in-memory data structures. Apple File System Reference......Page 1 About Apple File System......Page 6 uuid_t......Page 8 obj_phys_t......Page 9 Supporting Data Types......Page 10 Object Identifier Constants......Page 11 Object Type Masks......Page 12 Object Types......Page 13 Object Type Flags......Page 17 Booting from an Apple File System Partition......Page 20 nx_efi_jumpstart_t......Page 22 Partition UUIDs......Page 23 Mounting an Apple File System Partition......Page 24 nx_superblock_t......Page 25 Optional Container Feature Flags......Page 34 Incompatible Container Feature Flags......Page 35 Block and Container Sizes......Page 36 checkpoint_mapping_t......Page 37 Checkpoint Flags......Page 39 evict_mapping_val_t......Page 40 omap_phys_t......Page 41 omap_val_t......Page 43 omap_snapshot_t......Page 44 Object Map Value Flags......Page 45 Object Map Flags......Page 46 Object Map Reaper Phases......Page 47 apfs_superblock_t......Page 48 apfs_modified_by_t......Page 55 Volume Flags......Page 56 Optional Volume Feature Flags......Page 58 Incompatible Volume Feature Flags......Page 59 File-System Objects......Page 61 j_key_t......Page 62 j_inode_val_t......Page 63 j_drec_key_t......Page 67 j_drec_hashed_key_t......Page 68 j_drec_val_t......Page 69 j_dir_stats_val_t......Page 70 j_xattr_val_t......Page 71 j_obj_types......Page 73 j_obj_kinds......Page 75 j_inode_flags......Page 77 j_xattr_flags......Page 81 dir_rec_flags......Page 82 Inode Numbers......Page 83 File Extent Constants......Page 84 File Modes......Page 85 Directory Entry File Types......Page 86 j_phys_ext_val_t......Page 88 j_file_extent_key_t......Page 89 j_file_extent_val_t......Page 90 j_xattr_dstream_t......Page 91 j_dstream_t......Page 92 xf_blob_t......Page 94 Extended-Field Types......Page 95 Extended-Field Flags......Page 98 j_sibling_val_t......Page 100 j_sibling_map_val_t......Page 101 j_snap_metadata_val_t......Page 102 j_snap_name_key_t......Page 103 snap_meta_flags......Page 104 B-Tree......Page 105 btree_node_phys_t......Page 106 btree_info_fixed_t......Page 108 btree_info_t......Page 109 nloc_t......Page 110 kvoff_t......Page 111 B-Tree Flags......Page 112 B-Tree Table of Contents Constants......Page 113 B-Tree Node Flags......Page 114 B-Tree Node Constants......Page 115 spaceman_free_queue_key_t......Page 116 spaceman_phys_t......Page 117 Chunk Info Block Constants......Page 118 Internal-Pool Bitmap......Page 119 nx_reap_list_entry_t......Page 120 Reaper List Entry Flags......Page 121 omap_cleanup_state_t......Page 122 apfs_reap_state_t......Page 123 crypto_flags_t......Page 125 wrapped_meta_crypto_state_t......Page 126 Encryption Identifiers......Page 127 mk_obj_t......Page 129 Keybag Tags......Page 130 gbitmap_block_phys_t......Page 131 Encryption-Rolling Constants......Page 132 fusion_wbc_list_phys_t......Page 134 Fusion Middle-Tree Flags......Page 135 Symbol Index......Page 136 Revision History......Page 142