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package btrfs
import (
"time"
"lukeshu.com/btrfs-tools/pkg/binstruct"
)
type (
PhysicalAddr int64
LogicalAddr int64
ObjID 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 uint64 `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 uint64 `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
Reserved [0xf0]byte `bin:"off=23b, siz=f0"` // reserved /* 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)
Unused [0x235]byte `bin:"off=dcb, siz=235"` // current unused
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
}
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 DevItem struct {
DeviceID uint64 `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"`
}
|
