-package btrfs

-

-import (

- "fmt"

- "reflect"

-

- "lukeshu.com/btrfs-tools/pkg/binstruct"

- "lukeshu.com/btrfs-tools/pkg/btrfs/btrfsitem"

- "lukeshu.com/btrfs-tools/pkg/btrfs/btrfssum"

- "lukeshu.com/btrfs-tools/pkg/btrfs/btrfsvol"

- "lukeshu.com/btrfs-tools/pkg/util"

-)

-

-type Superblock struct {

- Checksum btrfssum.CSum `bin:"off=0x0, siz=0x20"` // Checksum of everything past this field (from 0x20 to 0x1000)

- FSUUID UUID `bin:"off=0x20, siz=0x10"` // FS UUID

- Self btrfsvol.PhysicalAddr `bin:"off=0x30, siz=0x8"` // physical address of this block (different for mirrors)

- Flags uint64 `bin:"off=0x38, siz=0x8"` // flags

- Magic [8]byte `bin:"off=0x40, siz=0x8"` // magic ('_BHRfS_M')

- Generation Generation `bin:"off=0x48, siz=0x8"`

-

- RootTree btrfsvol.LogicalAddr `bin:"off=0x50, siz=0x8"` // logical address of the root tree root

- ChunkTree btrfsvol.LogicalAddr `bin:"off=0x58, siz=0x8"` // logical address of the chunk tree root

- LogTree btrfsvol.LogicalAddr `bin:"off=0x60, siz=0x8"` // logical address of the log tree root

-

- LogRootTransID uint64 `bin:"off=0x68, siz=0x8"` // log_root_transid

- TotalBytes uint64 `bin:"off=0x70, siz=0x8"` // total_bytes

- BytesUsed uint64 `bin:"off=0x78, siz=0x8"` // bytes_used

- RootDirObjectID ObjID `bin:"off=0x80, siz=0x8"` // root_dir_objectid (usually 6)

- NumDevices uint64 `bin:"off=0x88, siz=0x8"` // num_devices

-

- SectorSize uint32 `bin:"off=0x90, siz=0x4"`

- NodeSize uint32 `bin:"off=0x94, siz=0x4"`

- LeafSize uint32 `bin:"off=0x98, siz=0x4"` // unused; must be the same as NodeSize

- StripeSize uint32 `bin:"off=0x9c, siz=0x4"`

- SysChunkArraySize uint32 `bin:"off=0xa0, siz=0x4"`

-

- ChunkRootGeneration Generation `bin:"off=0xa4, siz=0x8"`

- CompatFlags uint64 `bin:"off=0xac, siz=0x8"` // compat_flags

- CompatROFlags uint64 `bin:"off=0xb4, siz=0x8"` // compat_ro_flags - only implementations that support the flags can write to the filesystem

- IncompatFlags IncompatFlags `bin:"off=0xbc, siz=0x8"` // incompat_flags - only implementations that support the flags can use the filesystem

- ChecksumType btrfssum.CSumType `bin:"off=0xc4, siz=0x2"`

-

- RootLevel uint8 `bin:"off=0xc6, siz=0x1"` // root_level

- ChunkLevel uint8 `bin:"off=0xc7, siz=0x1"` // chunk_root_level

- LogLevel uint8 `bin:"off=0xc8, siz=0x1"` // log_root_level

-

- DevItem btrfsitem.Dev `bin:"off=0xc9, siz=0x62"` // DEV_ITEM data for this device

- Label [0x100]byte `bin:"off=0x12b, siz=0x100"` // label (may not contain '/' or '\\')

- CacheGeneration Generation `bin:"off=0x22b, siz=0x8"`

- UUIDTreeGeneration Generation `bin:"off=0x233, siz=0x8"`

-

- // FeatureIncompatMetadataUUID

- MetadataUUID UUID `bin:"off=0x23b, siz=0x10"`

-

- // FeatureIncompatExtentTreeV2

- NumGlobalRoots uint64 `bin:"off=0x24b, siz=0x8"`

-

- // FeatureIncompatExtentTreeV2

- BlockGroupRoot btrfsvol.LogicalAddr `bin:"off=0x253, siz=0x8"`

- BlockGroupRootGeneration Generation `bin:"off=0x25b, siz=0x8"`

- BlockGroupRootLevel uint8 `bin:"off=0x263, siz=0x1"`

-

- Reserved [199]byte `bin:"off=0x264, siz=0xc7"` // future expansion

-

- SysChunkArray [0x800]byte `bin:"off=0x32b, siz=0x800"` // 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.

- SuperRoots [4]RootBackup `bin:"off=0xb2b, siz=0x2a0"`

-

- // Padded to 4096 bytes

- Padding [565]byte `bin:"off=0xdcb, siz=0x235"`

- binstruct.End `bin:"off=0x1000"`

-}

-

-func (sb Superblock) CalculateChecksum() (btrfssum.CSum, error) {

- data, err := binstruct.Marshal(sb)

- if err != nil {

- return btrfssum.CSum{}, err

- }

- return sb.ChecksumType.Sum(data[binstruct.StaticSize(btrfssum.CSum{}):])

-}

-

-func (sb Superblock) ValidateChecksum() error {

- stored := sb.Checksum

- calced, err := sb.CalculateChecksum()

- if err != nil {

- return err

- }

- if calced != stored {

- return fmt.Errorf("superblock checksum mismatch: stored=%v calculated=%v",

- stored, calced)

- }

- return nil

-}

-

-func (a Superblock) Equal(b Superblock) bool {

- a.Checksum = btrfssum.CSum{}

- a.Self = 0

-

- b.Checksum = btrfssum.CSum{}

- b.Self = 0

-

- return reflect.DeepEqual(a, b)

-}

-

-func (sb Superblock) EffectiveMetadataUUID() UUID {

- if !sb.IncompatFlags.Has(FeatureIncompatMetadataUUID) {

- return sb.FSUUID

- }

- return sb.MetadataUUID

-}

-

-type SysChunk struct {

- Key Key

- Chunk btrfsitem.Chunk

-}

-

-func (sc SysChunk) MarshalBinary() ([]byte, error) {

- dat, err := binstruct.Marshal(sc.Key)

- if err != nil {

- return dat, fmt.Errorf("%T.MarshalBinary: %w", sc, err)

- }

- _dat, err := binstruct.Marshal(sc.Chunk)

- dat = append(dat, _dat...)

- if err != nil {

- return dat, fmt.Errorf("%T.MarshalBinary: %w", sc, err)

- }

- return dat, nil

-}

-

-func (sc *SysChunk) UnmarshalBinary(dat []byte) (int, error) {

- n, err := binstruct.Unmarshal(dat, &sc.Key)

- if err != nil {

- return n, fmt.Errorf("%T.UnmarshalBinary: %w", *sc, err)

- }

- _n, err := binstruct.Unmarshal(dat[n:], &sc.Chunk)

- n += _n

- if err != nil {

- return n, fmt.Errorf("%T.UnmarshalBinary: %w", *sc, err)

- }

- return n, nil

-}

-

-func (sb Superblock) ParseSysChunkArray() ([]SysChunk, error) {

- dat := sb.SysChunkArray[:sb.SysChunkArraySize]

- var ret []SysChunk

- for len(dat) > 0 {

- var pair SysChunk

- n, err := binstruct.Unmarshal(dat, &pair)

- dat = dat[n:]

- if err != nil {

- return nil, err

- }

- ret = append(ret, pair)

- }

- return ret, nil

-}

-

-type RootBackup struct {

- TreeRoot ObjID `bin:"off=0x0, siz=0x8"`

- TreeRootGen Generation `bin:"off=0x8, siz=0x8"`

-

- ChunkRoot ObjID `bin:"off=0x10, siz=0x8"`

- ChunkRootGen Generation `bin:"off=0x18, siz=0x8"`

-

- ExtentRoot ObjID `bin:"off=0x20, siz=0x8"`

- ExtentRootGen Generation `bin:"off=0x28, siz=0x8"`

-

- FSRoot ObjID `bin:"off=0x30, siz=0x8"`

- FSRootGen Generation `bin:"off=0x38, siz=0x8"`

-

- DevRoot ObjID `bin:"off=0x40, siz=0x8"`

- DevRootGen Generation `bin:"off=0x48, siz=0x8"`

-

- ChecksumRoot ObjID `bin:"off=0x50, siz=0x8"`

- ChecksumRootGen Generation `bin:"off=0x58, siz=0x8"`

-

- TotalBytes uint64 `bin:"off=0x60, siz=0x8"`

- BytesUsed uint64 `bin:"off=0x68, siz=0x8"`

- NumDevices uint64 `bin:"off=0x70, siz=0x8"`

-

- Unused [8 * 4]byte `bin:"off=0x78, siz=0x20"`

-

- TreeRootLevel uint8 `bin:"off=0x98, siz=0x1"`

- ChunkRootLevel uint8 `bin:"off=0x99, siz=0x1"`

- ExtentRootLevel uint8 `bin:"off=0x9a, siz=0x1"`

- FSRootLevel uint8 `bin:"off=0x9b, siz=0x1"`

- DevRootLevel uint8 `bin:"off=0x9c, siz=0x1"`

- ChecksumRootLevel uint8 `bin:"off=0x9d, siz=0x1"`

-

- Padding [10]byte `bin:"off=0x9e, siz=0xa"`

- binstruct.End `bin:"off=0xa8"`

-}

-

-type IncompatFlags uint64

-

-const (

- FeatureIncompatMixedBackref = IncompatFlags(1 << iota)

- FeatureIncompatDefaultSubvol

- FeatureIncompatMixedGroups

- FeatureIncompatCompressLZO

- FeatureIncompatCompressZSTD

- FeatureIncompatBigMetadata // buggy

- FeatureIncompatExtendedIRef

- FeatureIncompatRAID56

- FeatureIncompatSkinnyMetadata

- FeatureIncompatNoHoles

- FeatureIncompatMetadataUUID

- FeatureIncompatRAID1C34

- FeatureIncompatZoned

- FeatureIncompatExtentTreeV2

-)

-

-var incompatFlagNames = []string{

- "FeatureIncompatMixedBackref",

- "FeatureIncompatDefaultSubvol",

- "FeatureIncompatMixedGroups",

- "FeatureIncompatCompressLZO",

- "FeatureIncompatCompressZSTD",

- "FeatureIncompatBigMetadata ",

- "FeatureIncompatExtendedIRef",

- "FeatureIncompatRAID56",

- "FeatureIncompatSkinnyMetadata",

- "FeatureIncompatNoHoles",

- "FeatureIncompatMetadataUUID",

- "FeatureIncompatRAID1C34",

- "FeatureIncompatZoned",

- "FeatureIncompatExtentTreeV2",

-}

-

-func (f IncompatFlags) Has(req IncompatFlags) bool { return f&req == req }

-func (f IncompatFlags) String() string {

- return util.BitfieldString(f, incompatFlagNames, util.HexLower)

-}