// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package btrfs
import (
"fmt"
"reflect"
"git.lukeshu.com/btrfs-progs-ng/lib/binstruct"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfssum"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
"git.lukeshu.com/btrfs-progs-ng/lib/fmtutil"
)
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, err
}
_dat, err := binstruct.Marshal(sc.Chunk)
dat = append(dat, _dat...)
if err != nil {
return dat, err
}
return dat, nil
}
func (sc *SysChunk) UnmarshalBinary(dat []byte) (int, error) {
n, err := binstruct.Unmarshal(dat, &sc.Key)
if err != nil {
return n, err
}
_n, err := binstruct.Unmarshal(dat[n:], &sc.Chunk)
n += _n
if err != nil {
return n, 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 fmtutil.BitfieldString(f, incompatFlagNames, fmtutil.HexLower)
}