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package btrfsitem
import (
"fmt"
"lukeshu.com/btrfs-tools/pkg/binstruct"
"lukeshu.com/btrfs-tools/pkg/btrfs/internal"
)
// Maps logical address to physical.
//
// key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID
// key.offset = logical_addr
type Chunk struct { // CHUNK_ITEM=228
Head ChunkHeader
Stripes []ChunkStripe
}
type ChunkHeader struct {
Size internal.AddrDelta `bin:"off=0x0, siz=0x8"`
Owner internal.ObjID `bin:"off=0x8, siz=0x8"` // root referencing this chunk (always EXTENT_TREE_OBJECTID=2)
StripeLen uint64 `bin:"off=0x10, siz=0x8"` // ???
Type BlockGroupFlags `bin:"off=0x18, siz=0x8"`
IOOptimalAlign uint32 `bin:"off=0x20, siz=0x4"`
IOOptimalWidth uint32 `bin:"off=0x24, siz=0x4"`
IOMinSize uint32 `bin:"off=0x28, siz=0x4"` // sector size
NumStripes uint16 `bin:"off=0x2c, siz=0x2"` // [ignored-when-writing]
SubStripes uint16 `bin:"off=0x2e, siz=0x2"` // ???
binstruct.End `bin:"off=0x30"`
}
type ChunkStripe struct {
DeviceID internal.ObjID `bin:"off=0x0, siz=0x8"`
Offset internal.PhysicalAddr `bin:"off=0x8, siz=0x8"`
DeviceUUID internal.UUID `bin:"off=0x10, siz=0x10"`
binstruct.End `bin:"off=0x20"`
}
func (chunk *Chunk) UnmarshalBinary(dat []byte) (int, error) {
n, err := binstruct.Unmarshal(dat, &chunk.Head)
if err != nil {
return n, err
}
chunk.Stripes = nil
for i := 0; i < int(chunk.Head.NumStripes); i++ {
var stripe ChunkStripe
_n, err := binstruct.Unmarshal(dat[n:], &stripe)
n += _n
if err != nil {
return n, fmt.Errorf("%T.UnmarshalBinary: %w", *chunk, err)
}
chunk.Stripes = append(chunk.Stripes, stripe)
}
return n, nil
}
func (chunk Chunk) MarshalBinary() ([]byte, error) {
chunk.Head.NumStripes = uint16(len(chunk.Stripes))
ret, err := binstruct.Marshal(chunk.Head)
if err != nil {
return ret, err
}
for _, stripe := range chunk.Stripes {
_ret, err := binstruct.Marshal(stripe)
ret = append(ret, _ret...)
if err != nil {
return ret, fmt.Errorf("%T.MarshalBinary: %w", chunk, err)
}
}
return ret, nil
}
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