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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
// Package btrfsitem contains the definitions of all "items" that may
// be stored in a btrfs tree.
package btrfsitem
import (
"fmt"
"reflect"
"git.lukeshu.com/go/typedsync"
"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/btrfssum"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
"git.lukeshu.com/btrfs-progs-ng/lib/containers"
)
type Type = btrfsprim.ItemType
type Item interface {
isItem()
Free()
CloneItem() Item
}
type Error struct {
Dat []byte
Err error
}
var errorPool = &typedsync.Pool[*Error]{New: func() *Error { return new(Error) }}
func (*Error) isItem() {}
func (o *Error) Free() {
*o = Error{}
errorPool.Put(o)
}
func (o Error) Clone() Error { return o }
func (o *Error) CloneItem() Item {
ret, _ := errorPool.Get()
*ret = *o
return ret
}
func (o Error) MarshalBinary() ([]byte, error) {
return o.Dat, nil
}
func (o *Error) UnmarshalBinary(dat []byte) (int, error) {
o.Dat = dat
return len(dat), nil
}
// UnmarshalItem consumes the byte slice `dat`, unmarshaling it in to
// the item type specified by `key`.
//
// If there is an error, rather than returning a separate error value,
// return an Error item.
func UnmarshalItem(key btrfsprim.Key, csumType btrfssum.CSumType, dat []byte) Item {
var gotyp reflect.Type
if key.ItemType == UNTYPED_KEY {
var ok bool
gotyp, ok = untypedObjID2gotype[key.ObjectID]
if !ok {
ret, _ := errorPool.Get()
*ret = Error{
Dat: dat,
Err: fmt.Errorf("btrfsitem.UnmarshalItem({ItemType:%v, ObjectID:%v}, dat): unknown object ID for untyped item",
key.ItemType, key.ObjectID),
}
return ret
}
} else {
var ok bool
gotyp, ok = keytype2gotype[key.ItemType]
if !ok {
ret, _ := errorPool.Get()
*ret = Error{
Dat: dat,
Err: fmt.Errorf("btrfsitem.UnmarshalItem({ItemType:%v}, dat): unknown item type", key.ItemType),
}
return ret
}
}
ptr, _ := gotype2pool[gotyp].Get()
if csums, ok := ptr.(*ExtentCSum); ok {
csums.ChecksumSize = csumType.Size()
csums.Addr = btrfsvol.LogicalAddr(key.Offset)
}
n, err := binstruct.Unmarshal(dat, ptr)
if err != nil {
ptr.Free()
ret, _ := errorPool.Get()
*ret = Error{
Dat: dat,
Err: fmt.Errorf("btrfsitem.UnmarshalItem({ItemType:%v}, dat): %w", key.ItemType, err),
}
return ret
}
if n < len(dat) {
ptr.Free()
ret, _ := errorPool.Get()
*ret = Error{
Dat: dat,
Err: fmt.Errorf("btrfsitem.UnmarshalItem({ItemType:%v}, dat): left over data: got %v bytes but only consumed %v",
key.ItemType, len(dat), n),
}
return ret
}
return ptr
}
var bytePool containers.SlicePool[byte]
func cloneBytes(in []byte) []byte {
out := bytePool.Get(len(in))
copy(out, in)
return out
}
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