summaryrefslogtreecommitdiff
path: root/pkg/btrfs/btrfsitem/item_extent.go
blob: a86c2bd994257a95b045d58ac52ee2de7779cbe2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
package btrfsitem

import (
	"fmt"

	"lukeshu.com/btrfs-tools/pkg/binstruct"
	"lukeshu.com/btrfs-tools/pkg/btrfs/internal"
	"lukeshu.com/btrfs-tools/pkg/util"
)

type Extent struct { // EXTENT_ITEM=168
	Head ExtentHeader
	Info TreeBlockInfo // only if .Head.Flags.Has(EXTENT_FLAG_TREE_BLOCK)
	Refs []ExtentInlineRef
}

func (o *Extent) UnmarshalBinary(dat []byte) (int, error) {
	n, err := binstruct.Unmarshal(dat, &o.Head)
	if err != nil {
		return n, err
	}
	if o.Head.Flags.Has(EXTENT_FLAG_TREE_BLOCK) {
		_n, err := binstruct.Unmarshal(dat[n:], &o.Info)
		n += _n
		if err != nil {
			return n, err
		}
	}
	o.Refs = nil
	for n < len(dat) {
		var ref ExtentInlineRef
		_n, err := binstruct.Unmarshal(dat[n:], &ref)
		n += _n
		o.Refs = append(o.Refs, ref)
		if err != nil {
			return n, err
		}
	}
	return n, nil
}

func (o Extent) MarshalBinary() ([]byte, error) {
	dat, err := binstruct.Marshal(o.Head)
	if err != nil {
		return dat, err
	}
	if o.Head.Flags.Has(EXTENT_FLAG_TREE_BLOCK) {
		bs, err := binstruct.Marshal(o.Info)
		dat = append(dat, bs...)
		if err != nil {
			return dat, err
		}
	}
	for _, ref := range o.Refs {
		bs, err := binstruct.Marshal(ref)
		dat = append(dat, bs...)
		if err != nil {
			return dat, err
		}
	}
	return dat, nil
}

type ExtentHeader struct {
	Refs          int64       `bin:"off=0, siz=8"`
	Generation    int64       `bin:"off=8, siz=8"`
	Flags         ExtentFlags `bin:"off=16, siz=8"`
	binstruct.End `bin:"off=24"`
}

type TreeBlockInfo struct {
	Key           internal.Key `bin:"off=0, siz=0x11"`
	Level         uint8        `bin:"off=0x11, siz=0x8"`
	binstruct.End `bin:"off=0x19"`
}

type ExtentFlags uint64

const (
	EXTENT_FLAG_DATA = ExtentFlags(1 << iota)
	EXTENT_FLAG_TREE_BLOCK
)

var extentFlagNames = []string{
	"DATA",
	"TREE_BLOCK",
}

func (f ExtentFlags) Has(req ExtentFlags) bool { return f&req == req }
func (f ExtentFlags) String() string           { return util.BitfieldString(f, extentFlagNames, util.HexNone) }

type ExtentInlineRef struct {
	Type          Type   `bin:"off=0, siz=1"`
	Offset        uint64 `bin:"off=1, siz=8"`
	binstruct.End `bin:"off=9"`
	Body          Item `bin:"-"`
}

func (o *ExtentInlineRef) UnmarshalBinary(dat []byte) (int, error) {
	n, err := binstruct.UnmarshalWithoutInterface(dat, o)
	if err != nil {
		return n, err
	}
	switch o.Type {
	case TREE_BLOCK_REF_KEY, SHARED_BLOCK_REF_KEY:
		o.Body = Empty{}
	case EXTENT_DATA_REF_KEY:
		return n, fmt.Errorf("the C code to do this doesn't make any sense")
	case SHARED_DATA_REF_KEY:
		var sref SharedDataRef
		_n, err := binstruct.Unmarshal(dat[n:], &sref)
		n += _n
		o.Body = sref
		if err != nil {
			return n, err
		}
	}
	return n, nil
}

func (o ExtentInlineRef) MarshalBinary() ([]byte, error) {
	dat, err := binstruct.MarshalWithoutInterface(o)
	if err != nil {
		return dat, err
	}
	bs, err := binstruct.Marshal(o.Body)
	dat = append(dat, bs...)
	if err != nil {
		return dat, err
	}
	return dat, nil
}