/
msg_reader.go
202 lines (164 loc) · 3.44 KB
/
msg_reader.go
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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
package pgx
import (
"bufio"
"encoding/binary"
"errors"
"io"
"io/ioutil"
)
// msgReader is a helper that reads values from a PostgreSQL message.
type msgReader struct {
reader *bufio.Reader
buf [128]byte
msgBytesRemaining int32
err error
}
// Err returns any error that the msgReader has experienced
func (r *msgReader) Err() error {
return r.err
}
// fatal tells r that a Fatal error has occurred
func (r *msgReader) fatal(err error) {
r.err = err
}
// rxMsg reads the type and size of the next message.
func (r *msgReader) rxMsg() (t byte, err error) {
if r.err != nil {
return 0, err
}
if r.msgBytesRemaining > 0 {
io.CopyN(ioutil.Discard, r.reader, int64(r.msgBytesRemaining))
}
b := r.buf[0:5]
_, err = io.ReadFull(r.reader, b)
r.msgBytesRemaining = int32(binary.BigEndian.Uint32(b[1:])) - 4
return b[0], err
}
func (r *msgReader) readByte() byte {
if r.err != nil {
return 0
}
r.msgBytesRemaining -= 1
if r.msgBytesRemaining < 0 {
r.fatal(errors.New("read past end of message"))
return 0
}
b, err := r.reader.ReadByte()
if err != nil {
r.fatal(err)
return 0
}
return b
}
func (r *msgReader) readInt16() int16 {
if r.err != nil {
return 0
}
r.msgBytesRemaining -= 2
if r.msgBytesRemaining < 0 {
r.fatal(errors.New("read past end of message"))
return 0
}
b := r.buf[0:2]
_, err := io.ReadFull(r.reader, b)
if err != nil {
r.fatal(err)
return 0
}
return int16(binary.BigEndian.Uint16(b))
}
func (r *msgReader) readInt32() int32 {
if r.err != nil {
return 0
}
r.msgBytesRemaining -= 4
if r.msgBytesRemaining < 0 {
r.fatal(errors.New("read past end of message"))
return 0
}
b := r.buf[0:4]
_, err := io.ReadFull(r.reader, b)
if err != nil {
r.fatal(err)
return 0
}
return int32(binary.BigEndian.Uint32(b))
}
func (r *msgReader) readInt64() int64 {
if r.err != nil {
return 0
}
r.msgBytesRemaining -= 8
if r.msgBytesRemaining < 0 {
r.fatal(errors.New("read past end of message"))
return 0
}
b := r.buf[0:8]
_, err := io.ReadFull(r.reader, b)
if err != nil {
r.fatal(err)
return 0
}
return int64(binary.BigEndian.Uint64(b))
}
func (r *msgReader) readOid() Oid {
return Oid(r.readInt32())
}
// readCString reads a null terminated string
func (r *msgReader) readCString() string {
if r.err != nil {
return ""
}
b, err := r.reader.ReadBytes(0)
if err != nil {
r.fatal(err)
return ""
}
r.msgBytesRemaining -= int32(len(b))
if r.msgBytesRemaining < 0 {
r.fatal(errors.New("read past end of message"))
return ""
}
return string(b[0 : len(b)-1])
}
// readString reads count bytes and returns as string
func (r *msgReader) readString(count int32) string {
if r.err != nil {
return ""
}
r.msgBytesRemaining -= count
if r.msgBytesRemaining < 0 {
r.fatal(errors.New("read past end of message"))
return ""
}
var b []byte
if count <= int32(len(r.buf)) {
b = r.buf[0:int(count)]
} else {
b = make([]byte, int(count))
}
_, err := io.ReadFull(r.reader, b)
if err != nil {
r.fatal(err)
return ""
}
return string(b)
}
// readBytes reads count bytes and returns as []byte
func (r *msgReader) readBytes(count int32) []byte {
if r.err != nil {
return nil
}
r.msgBytesRemaining -= count
if r.msgBytesRemaining < 0 {
r.fatal(errors.New("read past end of message"))
return nil
}
b := make([]byte, int(count))
_, err := io.ReadFull(r.reader, b)
if err != nil {
r.fatal(err)
return nil
}
return b
}