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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package btrfsitem
import (
"fmt"
"git.lukeshu.com/btrfs-progs-ng/lib/binstruct"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
)
// FileExtent items map from regions in a file to regions in the
// logical address space.
//
// Compare with:
//
// - Extents, which map from regions in the logical address space to
// regions in a file.
// - Metadata, which are like Extents but without .Info.
//
// Key:
//
// key.objectid = inode
// key.offset = offset within file
type FileExtent struct { // complex EXTENT_DATA=108
Generation btrfsprim.Generation `bin:"off=0x0, siz=0x8"` // transaction ID that created this extent
RAMBytes int64 `bin:"off=0x8, siz=0x8"` // upper bound of what compressed data will decompress to
// 32 bits describing the data encoding
Compression CompressionType `bin:"off=0x10, siz=0x1"`
Encryption uint8 `bin:"off=0x11, siz=0x1"`
OtherEncoding uint16 `bin:"off=0x12, siz=0x2"` // reserved for later use
Type FileExtentType `bin:"off=0x14, siz=0x1"` // inline data or real extent
binstruct.End `bin:"off=0x15"`
// only one of these, depending on .Type
BodyInline []byte `bin:"-"` // .Type == FILE_EXTENT_INLINE
BodyExtent FileExtentExtent `bin:"-"` // .Type == FILE_EXTENT_REG or FILE_EXTENT_PREALLOC
}
type FileExtentExtent struct {
// Position and size of extent within the device
DiskByteNr btrfsvol.LogicalAddr `bin:"off=0x0, siz=0x8"`
DiskNumBytes btrfsvol.AddrDelta `bin:"off=0x8, siz=0x8"`
// Position of data within the extent
Offset btrfsvol.AddrDelta `bin:"off=0x10, siz=0x8"`
// Decompressed/unencrypted size
NumBytes int64 `bin:"off=0x18, siz=0x8"`
binstruct.End `bin:"off=0x20"`
}
func (o *FileExtent) Free() {
bytePool.Put(o.BodyInline)
*o = FileExtent{}
fileExtentPool.Put(o)
}
func (o FileExtent) Clone() FileExtent {
o.BodyInline = cloneBytes(o.BodyInline)
return o
}
func (o *FileExtent) UnmarshalBinary(dat []byte) (int, error) {
n, err := binstruct.UnmarshalWithoutInterface(dat, o)
if err != nil {
return n, err
}
switch o.Type {
case FILE_EXTENT_INLINE:
o.BodyInline = cloneBytes(dat[n:])
n += len(o.BodyInline)
case FILE_EXTENT_REG, FILE_EXTENT_PREALLOC:
_n, err := binstruct.Unmarshal(dat[n:], &o.BodyExtent)
n += _n
if err != nil {
return n, err
}
default:
return n, fmt.Errorf("unknown file extent type %v", o.Type)
}
return n, nil
}
func (o FileExtent) MarshalBinary() ([]byte, error) {
dat, err := binstruct.MarshalWithoutInterface(o)
if err != nil {
return dat, err
}
switch o.Type {
case FILE_EXTENT_INLINE:
dat = append(dat, o.BodyInline...)
case FILE_EXTENT_REG, FILE_EXTENT_PREALLOC:
bs, err := binstruct.Marshal(o.BodyExtent)
dat = append(dat, bs...)
if err != nil {
return dat, err
}
default:
return dat, fmt.Errorf("unknown file extent type %v", o.Type)
}
return dat, nil
}
type FileExtentType uint8
const (
FILE_EXTENT_INLINE FileExtentType = iota
FILE_EXTENT_REG
FILE_EXTENT_PREALLOC
)
var fileExtentTypeNames = []string{
"inline",
"regular",
"prealloc",
}
func (o FileExtent) Size() (int64, error) {
switch o.Type {
case FILE_EXTENT_INLINE:
return int64(len(o.BodyInline)), nil
case FILE_EXTENT_REG, FILE_EXTENT_PREALLOC:
return o.BodyExtent.NumBytes, nil
default:
return 0, fmt.Errorf("unknown file extent type %v", o.Type)
}
}
func (fet FileExtentType) String() string {
name := "unknown"
if int(fet) < len(fileExtentTypeNames) {
name = fileExtentTypeNames[fet]
}
return fmt.Sprintf("%d (%s)", fet, name)
}
type CompressionType uint8
const (
COMPRESS_NONE CompressionType = iota
COMPRESS_ZLIB
COMPRESS_LZO
COMPRESS_ZSTD
)
var compressionTypeNames = []string{
"none",
"zlib",
"lzo",
"zstd",
}
func (ct CompressionType) String() string {
name := "unknown"
if int(ct) < len(compressionTypeNames) {
name = compressionTypeNames[ct]
}
return fmt.Sprintf("%d (%s)", ct, name)
}
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