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
133
134
135
136
137
138
139
140
141
|
package index
import (
"bytes"
"crypto/sha1"
"errors"
"hash"
"io"
"time"
"gopkg.in/src-d/go-git.v4/utils/binary"
)
var (
// EncodeVersionSupported is the range of supported index versions
EncodeVersionSupported uint32 = 2
// ErrInvalidTimestamp is returned by Encode if a Index with a Entry with
// negative timestamp values
ErrInvalidTimestamp = errors.New("negative timestamps are not allowed")
)
// An Encoder writes an Index to an output stream.
type Encoder struct {
w io.Writer
hash hash.Hash
}
// NewEncoder returns a new encoder that writes to w.
func NewEncoder(w io.Writer) *Encoder {
h := sha1.New()
mw := io.MultiWriter(w, h)
return &Encoder{mw, h}
}
// Encode writes the Index to the stream of the encoder.
func (e *Encoder) Encode(idx *Index) error {
// TODO: support versions v3 and v4
// TODO: support extensions
if idx.Version != EncodeVersionSupported {
return ErrUnsupportedVersion
}
if err := e.encodeHeader(idx); err != nil {
return err
}
if err := e.encodeEntries(idx); err != nil {
return err
}
return e.encodeFooter()
}
func (e *Encoder) encodeHeader(idx *Index) error {
return binary.Write(e.w,
indexSignature,
idx.Version,
uint32(len(idx.Entries)),
)
}
func (e *Encoder) encodeEntries(idx *Index) error {
for _, entry := range idx.Entries {
if err := e.encodeEntry(&entry); err != nil {
return err
}
wrote := entryHeaderLength + len(entry.Name)
if err := e.padEntry(wrote); err != nil {
return err
}
}
return nil
}
func (e *Encoder) encodeEntry(entry *Entry) error {
if entry.IntentToAdd || entry.SkipWorktree {
return ErrUnsupportedVersion
}
sec, nsec, err := e.timeToUint32(&entry.CreatedAt)
if err != nil {
return err
}
msec, mnsec, err := e.timeToUint32(&entry.ModifiedAt)
if err != nil {
return err
}
flags := uint16(entry.Stage&0x3) << 12
if l := len(entry.Name); l < nameMask {
flags |= uint16(l)
} else {
flags |= nameMask
}
flow := []interface{}{
sec, nsec,
msec, mnsec,
entry.Dev,
entry.Inode,
entry.Mode,
entry.UID,
entry.GID,
entry.Size,
entry.Hash[:],
flags,
}
if err := binary.Write(e.w, flow...); err != nil {
return err
}
return binary.Write(e.w, []byte(entry.Name))
}
func (e *Encoder) timeToUint32(t *time.Time) (uint32, uint32, error) {
if t.IsZero() {
return 0, 0, nil
}
if t.Unix() < 0 || t.UnixNano() < 0 {
return 0, 0, ErrInvalidTimestamp
}
return uint32(t.Unix()), uint32(t.Nanosecond()), nil
}
func (e *Encoder) padEntry(wrote int) error {
padLen := 8 - wrote%8
_, err := e.w.Write(bytes.Repeat([]byte{'\x00'}, padLen))
return err
}
func (e *Encoder) encodeFooter() error {
return binary.Write(e.w, e.hash.Sum(nil))
}
|
