diff options
Diffstat (limited to 'pkg/btrfs/structs.go')
| -rw-r--r-- | pkg/btrfs/structs.go | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/pkg/btrfs/structs.go b/pkg/btrfs/structs.go new file mode 100644 index 0000000..92db216 --- /dev/null +++ b/pkg/btrfs/structs.go @@ -0,0 +1,217 @@ +package btrfs + +import ( + "time" + + "lukeshu.com/btrfs-tools/pkg/binstruct" +) + +type ( + PhysicalAddr int64 + LogicalAddr int64 +) + +type Key struct { + ObjectID ObjID `bin:"off=0, siz=8"` // Object ID. Each tree has its own set of Object IDs. + ItemType uint8 `bin:"off=8, siz=1"` // Item type. + Offset uint64 `bin:"off=9, siz=8"` // Offset. The meaning depends on the item type. + binstruct.End `bin:"off=11"` +} + +type Time struct { + Sec int64 `bin:"off=0, siz=8"` // Number of seconds since 1970-01-01T00:00:00Z. + NSec uint64 `bin:"off=8, siz=4"` // Number of nanoseconds since the beginning of the second. + binstruct.End `bin:"off=c"` +} + +func (t Time) ToStd() time.Time { + return time.Unix(t.Sec, int64(t.NSec)) +} + +type Superblock struct { + Checksum CSum `bin:"off=0, siz=20"` // Checksum of everything past this field (from 20 to 1000) + FSUUID UUID `bin:"off=20, siz=10"` // FS UUID + Self PhysicalAddr `bin:"off=30, siz=8"` // physical address of this block (different for mirrors) + Flags uint64 `bin:"off=38, siz=8"` // flags + Magic [8]byte `bin:"off=40, siz=8"` // magic ('_BHRfS_M') + Generation uint64 `bin:"off=48, siz=8"` // generation + + RootTree LogicalAddr `bin:"off=50, siz=8"` // logical address of the root tree root + ChunkTree LogicalAddr `bin:"off=58, siz=8"` // logical address of the chunk tree root + LogTree LogicalAddr `bin:"off=60, siz=8"` // logical address of the log tree root + + LogRootTransID uint64 `bin:"off=68, siz=8"` // log_root_transid + TotalBytes uint64 `bin:"off=70, siz=8"` // total_bytes + BytesUsed uint64 `bin:"off=78, siz=8"` // bytes_used + RootDirObjectID ObjID `bin:"off=80, siz=8"` // root_dir_objectid (usually 6) + NumDevices uint64 `bin:"off=88, siz=8"` // num_devices + + SectorSize uint32 `bin:"off=90, siz=4"` // sectorsize + NodeSize uint32 `bin:"off=94, siz=4"` // nodesize + LeafSize uint32 `bin:"off=98, siz=4"` // leafsize + StripeSize uint32 `bin:"off=9c, siz=4"` // stripesize + SysChunkArraySize uint32 `bin:"off=a0, siz=4"` // sys_chunk_array_size + + ChunkRootGeneration uint64 `bin:"off=a4, siz=8"` // chunk_root_generation + CompatFlags uint64 `bin:"off=ac, siz=8"` // compat_flags + CompatROFlags uint64 `bin:"off=b4, siz=8"` // compat_ro_flags - only implementations that support the flags can write to the filesystem + IncompatFlags IncompatFlags `bin:"off=bc, siz=8"` // incompat_flags - only implementations that support the flags can use the filesystem + ChecksumType uint16 `bin:"off=c4, siz=2"` // csum_type - Btrfs currently uses the CRC32c little-endian hash function with seed -1. + + RootLevel uint8 `bin:"off=c6, siz=1"` // root_level + ChunkLevel uint8 `bin:"off=c7, siz=1"` // chunk_root_level + LogLevel uint8 `bin:"off=c8, siz=1"` // log_root_level + + DevItem DevItem `bin:"off=c9, siz=62"` // DEV_ITEM data for this device + Label [0x100]byte `bin:"off=12b, siz=100"` // label (may not contain '/' or '\\') + CacheGeneration uint64 `bin:"off=22b, siz=8"` // cache_generation + UUIDTreeGeneration uint64 `bin:"off=233, siz=8"` // uuid_tree_generation + + // FeatureIncompatMetadataUUID + MetadataUUID UUID `bin:"off=23b, siz=10"` + + // FeatureIncompatExtentTreeV2 + NumGlobalRoots uint64 `bin:"off=24b, siz=8"` + + // FeatureIncompatExtentTreeV2 + BlockGroupRoot uint64 `bin:"off=253, siz=8"` + BlockGroupRootGeneration uint64 `bin:"off=25b, siz=8"` + BlockGroupRootLevel uint8 `bin:"off=263, siz=1"` + + Reserved [199]byte `bin:"off=264, siz=c7"` // future expansion + + SysChunkArray [0x800]byte `bin:"off=32b, siz=800"` // sys_chunk_array:(n bytes valid) Contains (KEY . CHUNK_ITEM) pairs for all SYSTEM chunks. This is needed to bootstrap the mapping from logical addresses to physical. + TODOSuperRoots [0x2a0]byte `bin:"off=b2b, siz=2a0"` // Contain super_roots (4 btrfs_root_backup) + + // Padded to 4096 bytes + Padding [565]byte `bin:"off=dcb, siz=235"` + binstruct.End `bin:"off=1000"` +} + +func (sb Superblock) CalculateChecksum() (CSum, error) { + data, err := binstruct.Marshal(sb) + if err != nil { + return CSum{}, err + } + return CRC32c(data[0x20:]), nil +} + +func (sb Superblock) EffectiveMetadataUUID() UUID { + if !sb.IncompatFlags.Has(FeatureIncompatMetadataUUID) { + return sb.FSUUID + } + return sb.MetadataUUID +} + +type SysChunk struct { + Key `bin:"off=0, siz=11"` + ChunkItem `bin:"off=11, siz=30"` + binstruct.End `bin:"off=41"` +} + +func (sb Superblock) ParseSysChunkArray() ([]SysChunk, error) { + dat := sb.SysChunkArray[:sb.SysChunkArraySize] + var ret []SysChunk + for len(dat) > 0 { + var pair SysChunk + if err := binstruct.Unmarshal(dat, &pair); err != nil { + return nil, err + } + dat = dat[0x41:] + + for i := 0; i < int(pair.ChunkItem.NumStripes); i++ { + var stripe ChunkItemStripe + if err := binstruct.Unmarshal(dat, &stripe); err != nil { + return nil, err + } + pair.ChunkItem.Stripes = append(pair.ChunkItem.Stripes, stripe) + dat = dat[0x20:] + } + + ret = append(ret, pair) + } + return ret, nil +} + +type NodeHeader struct { + Checksum CSum `bin:"off=0, siz=20"` // Checksum of everything after this field (from 20 to the end of the node) + MetadataUUID UUID `bin:"off=20, siz=10"` // FS UUID + Addr LogicalAddr `bin:"off=30, siz=8"` // Logical address of this node + Flags uint64 `bin:"off=38, siz=8"` // Flags + ChunkTreeUUID UUID `bin:"off=40, siz=10"` // Chunk tree UUID + Generation uint64 `bin:"off=50, siz=8"` // Generation + OwnerTree TreeObjID `bin:"off=58, siz=8"` // The ID of the tree that contains this node + NumItems uint32 `bin:"off=60, siz=4"` // Number of items + Level uint8 `bin:"off=64, siz=1"` // Level (0 for leaf nodes) + binstruct.End `bin:"off=65"` +} + +type InternalNode struct { + NodeHeader + Body []KeyPointer +} + +type KeyPointer struct { + Key Key `bin:"off=0, siz=11"` + BlockNumber uint64 `bin:"off=11, siz=8"` + Generation uint64 `bin:"off=19, siz=8"` + binstruct.End `bin:"off=21"` +} + +type LeafNode struct { + NodeHeader + Body []Item +} + +type Item struct { + Key Key `bin:"off=0, siz=11"` + DataOffset uint32 `bin:"off=11, siz=4"` // relative to the end of the header (0x65) + DataSize uint32 `bin:"off=15, siz=4"` + binstruct.End `bin:"off=19"` +} + +type DevItem struct { + DeviceID ObjID `bin:"off=0, siz=8"` // device ID + + NumBytes uint64 `bin:"off=8, siz=8"` // number of bytes + NumBytesUsed uint64 `bin:"off=10, siz=8"` // number of bytes used + + IOOptimalAlign uint32 `bin:"off=18, siz=4"` // optimal I/O align + IOOptimalWidth uint32 `bin:"off=1c, siz=4"` // optimal I/O width + IOMinSize uint32 `bin:"off=20, siz=4"` // minimal I/O size (sector size) + + Type uint64 `bin:"off=24, siz=8"` // type + Generation uint64 `bin:"off=2c, siz=8"` // generation + StartOffset uint64 `bin:"off=34, siz=8"` // start offset + DevGroup uint32 `bin:"off=3c, siz=4"` // dev group + SeekSpeed uint8 `bin:"off=40, siz=1"` // seek speed + Bandwidth uint8 `bin:"off=41, siz=1"` // bandwidth + + DevUUID UUID `bin:"off=42, siz=10"` // device UUID + FSUUID UUID `bin:"off=52, siz=10"` // FS UUID + + binstruct.End `bin:"off=62"` +} + +type ChunkItem struct { + // Maps logical address to physical. + Size uint64 `bin:"off=0, siz=8"` // size of chunk (bytes) + Root ObjID `bin:"off=8, siz=8"` // root referencing this chunk (2) + StripeLen uint64 `bin:"off=10, siz=8"` // stripe length + Type uint64 `bin:"off=18, siz=8"` // type (same as flags for block group?) + IOOptimalAlign uint32 `bin:"off=20, siz=4"` // optimal io alignment + IOOptimalWidth uint32 `bin:"off=24, siz=4"` // optimal io width + IoMinSize uint32 `bin:"off=28, siz=4"` // minimal io size (sector size) + NumStripes uint16 `bin:"off=2c, siz=2"` // number of stripes + SubStripes uint16 `bin:"off=2e, siz=2"` // sub stripes + binstruct.End `bin:"off=30"` + Stripes []ChunkItemStripe `bin:"-"` +} + +type ChunkItemStripe struct { + // Stripes follow (for each number of stripes): + DeviceID ObjID `bin:"off=0, siz=8"` // device ID + Offset uint64 `bin:"off=8, siz=8"` // offset + DeviceUUID UUID `bin:"off=10, siz=10"` // device UUID + binstruct.End `bin:"off=20"` +} |