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
142
143
144
145
146
147
148
149
|
package sideband
import (
"errors"
"fmt"
"io"
"gopkg.in/src-d/go-git.v4/plumbing/format/pktline"
)
// ErrMaxPackedExceeded returned by Read, if the maximum packed size is exceeded
var ErrMaxPackedExceeded = errors.New("max. packed size exceeded")
// Progress allows to read the progress information
type Progress interface {
io.Reader
io.Writer
}
// Demuxer demultiplex the progress reports and error info interleaved with the
// packfile itself.
//
// A sideband has three different channels the main one, call PackData, contains
// the packfile data, the ErrorMessage channel, that contains server errors and
// the last one ProgressMessage channel containing information about the ongoing
// task happening in the server (optional, can be suppressed sending NoProgress
// or Quiet capabilities to the server)
//
// In order to demultiplex the data stream, method `Read` should be called to
// retrieve the PackData channel, the incoming data from the ProgressMessage is
// written at `Progress` (if any), if any message is retrieved from the
// ErrorMessage channel an error is returned and we can assume that the
// connection has been closed.
type Demuxer struct {
t Type
r io.Reader
s *pktline.Scanner
max int
pending []byte
// Progress is where the progress messages are stored
Progress Progress
}
// NewDemuxer returns a new Demuxer for the given t and read from r
func NewDemuxer(t Type, r io.Reader) *Demuxer {
max := MaxPackedSize64k
if t == Sideband {
max = MaxPackedSize
}
return &Demuxer{
t: t,
r: r,
max: max,
s: pktline.NewScanner(r),
}
}
// Read reads up to len(p) bytes from the PackData channel into p, an error can
// be return if an error happens when reading or if a message is sent in the
// ErrorMessage channel.
//
// When a ProgressMessage is read, is not copy to b, instead of this is written
// to the Progress
func (d *Demuxer) Read(b []byte) (n int, err error) {
var read, req int
req = len(b)
for read < req {
n, err := d.doRead(b[read:req])
read += n
if err != nil {
return read, err
}
}
return read, nil
}
func (d *Demuxer) doRead(b []byte) (int, error) {
read, err := d.nextPackData()
size := len(read)
wanted := len(b)
if size > wanted {
d.pending = read[wanted:]
}
if wanted > size {
wanted = size
}
size = copy(b, read[:wanted])
return size, err
}
func (d *Demuxer) nextPackData() ([]byte, error) {
content := d.getPending()
if len(content) != 0 {
return content, nil
}
if !d.s.Scan() {
if err := d.s.Err(); err != nil {
return nil, err
}
return nil, io.EOF
}
content = d.s.Bytes()
size := len(content)
if size == 0 {
return nil, nil
} else if size > d.max {
return nil, ErrMaxPackedExceeded
}
switch Channel(content[0]) {
case PackData:
return content[1:], nil
case ProgressMessage:
if d.Progress != nil {
_, err := d.Progress.Write(content[1:])
return nil, err
}
case ErrorMessage:
return nil, fmt.Errorf("unexpected error: %s", content[1:])
default:
return nil, fmt.Errorf("unknown channel %s", content)
}
return nil, nil
}
func (d *Demuxer) getPending() (b []byte) {
if len(d.pending) == 0 {
return nil
}
content := d.pending
d.pending = nil
return content
}
|
