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
|
// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package eventchannel contains functionality for sending any protobuf message
// on a socketpair.
//
// The wire format is a uvarint length followed by a binary protobuf.Any
// message.
package eventchannel
import (
"encoding/binary"
"fmt"
"golang.org/x/sys/unix"
"google.golang.org/protobuf/encoding/prototext"
"google.golang.org/protobuf/proto"
pb "gvisor.dev/gvisor/pkg/eventchannel/eventchannel_go_proto"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/unet"
)
// Emitter emits a proto message.
type Emitter interface {
// Emit writes a single eventchannel message to an emitter. Emit should
// return hangup = true to indicate an emitter has "hung up" and no further
// messages should be directed to it.
Emit(msg proto.Message) (hangup bool, err error)
// Close closes this emitter. Emit cannot be used after Close is called.
Close() error
}
// DefaultEmitter is the default emitter. Calls to Emit and AddEmitter are sent
// to this Emitter.
var DefaultEmitter = &multiEmitter{}
// Emit is a helper method that calls DefaultEmitter.Emit.
func Emit(msg proto.Message) error {
_, err := DefaultEmitter.Emit(msg)
return err
}
// AddEmitter is a helper method that calls DefaultEmitter.AddEmitter.
func AddEmitter(e Emitter) {
DefaultEmitter.AddEmitter(e)
}
// multiEmitter is an Emitter that forwards messages to multiple Emitters.
type multiEmitter struct {
// mu protects emitters.
mu sync.Mutex
// emitters is initialized lazily in AddEmitter.
emitters map[Emitter]struct{}
}
// Emit emits a message using all added emitters.
func (me *multiEmitter) Emit(msg proto.Message) (bool, error) {
me.mu.Lock()
defer me.mu.Unlock()
var err error
for e := range me.emitters {
hangup, eerr := e.Emit(msg)
if eerr != nil {
if err == nil {
err = fmt.Errorf("error emitting %v: on %v: %v", msg, e, eerr)
} else {
err = fmt.Errorf("%v; on %v: %v", err, e, eerr)
}
// Log as well, since most callers ignore the error.
log.Warningf("Error emitting %v on %v: %v", msg, e, eerr)
}
if hangup {
log.Infof("Hangup on eventchannel emitter %v.", e)
delete(me.emitters, e)
}
}
return false, err
}
// AddEmitter adds a new emitter.
func (me *multiEmitter) AddEmitter(e Emitter) {
me.mu.Lock()
defer me.mu.Unlock()
if me.emitters == nil {
me.emitters = make(map[Emitter]struct{})
}
me.emitters[e] = struct{}{}
}
// Close closes all emitters. If any Close call errors, it returns the first
// one encountered.
func (me *multiEmitter) Close() error {
me.mu.Lock()
defer me.mu.Unlock()
var err error
for e := range me.emitters {
if eerr := e.Close(); err == nil && eerr != nil {
err = eerr
}
delete(me.emitters, e)
}
return err
}
// socketEmitter emits proto messages on a socket.
type socketEmitter struct {
socket *unet.Socket
}
// SocketEmitter creates a new event channel based on the given fd.
//
// SocketEmitter takes ownership of fd.
func SocketEmitter(fd int) (Emitter, error) {
s, err := unet.NewSocket(fd)
if err != nil {
return nil, err
}
return &socketEmitter{
socket: s,
}, nil
}
// Emit implements Emitter.Emit.
func (s *socketEmitter) Emit(msg proto.Message) (bool, error) {
any, err := newAny(msg)
if err != nil {
return false, err
}
bufMsg, err := proto.Marshal(any)
if err != nil {
return false, err
}
// Wire format is uvarint message length followed by binary proto.
p := make([]byte, binary.MaxVarintLen64)
n := binary.PutUvarint(p, uint64(len(bufMsg)))
p = append(p[:n], bufMsg...)
for done := 0; done < len(p); {
n, err := s.socket.Write(p[done:])
if err != nil {
return (err == unix.EPIPE), err
}
done += n
}
return false, nil
}
// Close implements Emitter.Emit.
func (s *socketEmitter) Close() error {
return s.socket.Close()
}
// debugEmitter wraps an emitter to emit stringified event messages. This is
// useful for debugging -- when the messages are intended for humans.
type debugEmitter struct {
inner Emitter
}
// DebugEmitterFrom creates a new event channel emitter by wrapping an existing
// raw emitter.
func DebugEmitterFrom(inner Emitter) Emitter {
return &debugEmitter{
inner: inner,
}
}
func (d *debugEmitter) Emit(msg proto.Message) (bool, error) {
text, err := prototext.Marshal(msg)
if err != nil {
return false, err
}
ev := &pb.DebugEvent{
Name: string(msg.ProtoReflect().Descriptor().FullName()),
Text: string(text),
}
return d.inner.Emit(ev)
}
func (d *debugEmitter) Close() error {
return d.inner.Close()
}
|
