stuff

1 files changed, 279 insertions, 0 deletions

diff --git a/pkg/btrfs/types_structs.go b/pkg/btrfs/types_structs.go
new file mode 100644
index 0000000..6ab3b93
--- /dev/null
+++ b/pkg/btrfs/types_structs.go
@@ -0,0 +1,279 @@
+package btrfs
+
+import (
+	"fmt"
+	"reflect"
+	"time"
+
+	"lukeshu.com/btrfs-tools/pkg/binstruct"
+)
+
+type (
+	PhysicalAddr int64
+	LogicalAddr  int64
+	Generation   uint64
+)
+
+type Key struct {
+	ObjectID      ObjID    `bin:"off=0, siz=8"` // Each tree has its own set of Object IDs.
+	ItemType      ItemType `bin:"off=8, siz=1"`
+	Offset        uint64   `bin:"off=9, siz=8"` // 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 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            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    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           ObjID      `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"`
+	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
+		if err := binstruct.Unmarshal(dat, &pair); err != nil {
+			return nil, err
+		}
+		dat = dat[0x41:]
+
+		for i := 0; i < int(pair.Chunk.NumStripes); i++ {
+			var stripe Stripe
+			if err := binstruct.Unmarshal(dat, &stripe); err != nil {
+				return nil, err
+			}
+			pair.Chunk.Stripes = append(pair.Chunk.Stripes, stripe)
+			dat = dat[0x20:]
+		}
+
+		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 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    Generation  `bin:"off=50, siz=8"`  // Generation
+	Owner         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    Generation `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  Generation `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 Chunk struct {
+	// Maps logical address to physical.
+	Size           uint64 `bin:"off=0,  siz=8"` // size of chunk (bytes)
+	Owner          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        []Stripe `bin:"-"`
+}
+
+type Stripe 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"`
+}