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package btrfs
import (
"fmt"
"reflect"
"lukeshu.com/btrfs-tools/pkg/binstruct"
"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsitem"
"lukeshu.com/btrfs-tools/pkg/util"
)
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 Generation `bin:"off=48, siz=8"`
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"`
NodeSize uint32 `bin:"off=94, siz=4"`
LeafSize uint32 `bin:"off=98, siz=4"` // unused; must be the same as NodeSize
StripeSize uint32 `bin:"off=9c, siz=4"`
SysChunkArraySize uint32 `bin:"off=a0, siz=4"`
ChunkRootGeneration Generation `bin:"off=a4, siz=8"`
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 btrfsitem.Dev `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 Generation `bin:"off=22b, siz=8"`
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 LogicalAddr `bin:"off=253, siz=8"`
BlockGroupRootGeneration Generation `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.
SuperRoots [4]RootBackup `bin:"off=b2b, siz=2a0"`
// 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) ValidateChecksum() error {
stored := sb.Checksum
calced, err := sb.CalculateChecksum()
if err != nil {
return err
}
if !calced.Equal(stored) {
return fmt.Errorf("superblock checksum mismatch: stored=%s calculated=%s",
stored, calced)
}
return nil
}
func (a Superblock) Equal(b Superblock) bool {
a.Checksum = CSum{}
a.Self = 0
b.Checksum = 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 `bin:"off=0, siz=11"`
btrfsitem.Chunk `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
n, err := binstruct.Unmarshal(dat, &pair)
dat = dat[n:]
if err != nil {
return nil, err
}
for i := 0; i < int(pair.Chunk.NumStripes); i++ {
var stripe btrfsitem.ChunkStripe
n, err := binstruct.Unmarshal(dat, &stripe)
dat = dat[n:]
if err != nil {
return nil, err
}
pair.Chunk.Stripes = append(pair.Chunk.Stripes, stripe)
}
ret = append(ret, pair)
}
return ret, nil
}
type RootBackup struct {
TreeRoot ObjID `bin:"off=0, siz=8"`
TreeRootGen Generation `bin:"off=8, siz=8"`
ChunkRoot ObjID `bin:"off=10, siz=8"`
ChunkRootGen Generation `bin:"off=18, siz=8"`
ExtentRoot ObjID `bin:"off=20, siz=8"`
ExtentRootGen Generation `bin:"off=28, siz=8"`
FSRoot ObjID `bin:"off=30, siz=8"`
FSRootGen Generation `bin:"off=38, siz=8"`
DevRoot ObjID `bin:"off=40, siz=8"`
DevRootGen Generation `bin:"off=48, siz=8"`
ChecksumRoot ObjID `bin:"off=50, siz=8"`
ChecksumRootGen Generation `bin:"off=58, siz=8"`
TotalBytes uint64 `bin:"off=60, siz=8"`
BytesUsed uint64 `bin:"off=68, siz=8"`
NumDevices uint64 `bin:"off=70, siz=8"`
Unused [8 * 4]byte `bin:"off=78, siz=20"`
TreeRootLevel uint8 `bin:"off=98, siz=1"`
ChunkRootLevel uint8 `bin:"off=99, siz=1"`
ExtentRootLevel uint8 `bin:"off=9a, siz=1"`
FSRootLevel uint8 `bin:"off=9b, siz=1"`
DevRootLevel uint8 `bin:"off=9c, siz=1"`
ChecksumRootLevel uint8 `bin:"off=9d, siz=1"`
Padding [10]byte `bin:"off=9e, siz=a"`
binstruct.End `bin:"off=a8"`
}
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) }
|
