3 files changed, 254 insertions, 0 deletions
diff --git a/pkg/eventchannel/event.go b/pkg/eventchannel/event.go
new file mode 100644
index 000000000..4c8ae573b
--- /dev/null
+++ b/pkg/eventchannel/event.go
@@ -0,0 +1,165 @@
+// 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"
+	"sync"
+	"syscall"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/golang/protobuf/ptypes"
+	pb "gvisor.googlesource.com/gvisor/pkg/eventchannel/eventchannel_go_proto"
+	"gvisor.googlesource.com/gvisor/pkg/log"
+	"gvisor.googlesource.com/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
+}
+
+var (
+	mu       sync.Mutex
+	emitters = make(map[Emitter]struct{})
+)
+
+// Emit emits a message using all added emitters.
+func Emit(msg proto.Message) error {
+	mu.Lock()
+	defer mu.Unlock()
+
+	var err error
+	for e := range 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(emitters, e)
+		}
+	}
+
+	return err
+}
+
+// AddEmitter adds a new emitter.
+func AddEmitter(e Emitter) {
+	mu.Lock()
+	defer mu.Unlock()
+	emitters[e] = struct{}{}
+}
+
+func marshal(msg proto.Message) ([]byte, error) {
+	anypb, err := ptypes.MarshalAny(msg)
+	if err != nil {
+		return nil, err
+	}
+
+	// Wire format is uvarint message length followed by binary proto.
+	bufMsg, err := proto.Marshal(anypb)
+	if err != nil {
+		return nil, err
+	}
+	p := make([]byte, binary.MaxVarintLen64)
+	n := binary.PutUvarint(p, uint64(len(bufMsg)))
+	return append(p[:n], bufMsg...), nil
+}
+
+// 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) {
+	p, err := marshal(msg)
+	if err != nil {
+		return false, err
+	}
+	for done := 0; done < len(p); {
+		n, err := s.socket.Write(p[done:])
+		if err != nil {
+			return (err == syscall.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 wraping an existing
+// raw emitter.
+func DebugEmitterFrom(inner Emitter) Emitter {
+	return &debugEmitter{
+		inner: inner,
+	}
+}
+
+func (d *debugEmitter) Emit(msg proto.Message) (bool, error) {
+	ev := &pb.DebugEvent{
+		Name: proto.MessageName(msg),
+		Text: proto.MarshalTextString(msg),
+	}
+	return d.inner.Emit(ev)
+}
+
+func (d *debugEmitter) Close() error {
+	return d.inner.Close()
+}
diff --git a/pkg/eventchannel/eventchannel_go_proto/event.pb.go b/pkg/eventchannel/eventchannel_go_proto/event.pb.go
new file mode 100755
index 000000000..bb71ed3e6
--- /dev/null
+++ b/pkg/eventchannel/eventchannel_go_proto/event.pb.go
@@ -0,0 +1,85 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: pkg/eventchannel/event.proto
+
+package gvisor
+
+import (
+	fmt "fmt"
+	proto "github.com/golang/protobuf/proto"
+	math "math"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
+
+type DebugEvent struct {
+	Name                 string   `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+	Text                 string   `protobuf:"bytes,2,opt,name=text,proto3" json:"text,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *DebugEvent) Reset()         { *m = DebugEvent{} }
+func (m *DebugEvent) String() string { return proto.CompactTextString(m) }
+func (*DebugEvent) ProtoMessage()    {}
+func (*DebugEvent) Descriptor() ([]byte, []int) {
+	return fileDescriptor_fcfbd51abd9de962, []int{0}
+}
+
+func (m *DebugEvent) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_DebugEvent.Unmarshal(m, b)
+}
+func (m *DebugEvent) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_DebugEvent.Marshal(b, m, deterministic)
+}
+func (m *DebugEvent) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_DebugEvent.Merge(m, src)
+}
+func (m *DebugEvent) XXX_Size() int {
+	return xxx_messageInfo_DebugEvent.Size(m)
+}
+func (m *DebugEvent) XXX_DiscardUnknown() {
+	xxx_messageInfo_DebugEvent.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_DebugEvent proto.InternalMessageInfo
+
+func (m *DebugEvent) GetName() string {
+	if m != nil {
+		return m.Name
+	}
+	return ""
+}
+
+func (m *DebugEvent) GetText() string {
+	if m != nil {
+		return m.Text
+	}
+	return ""
+}
+
+func init() {
+	proto.RegisterType((*DebugEvent)(nil), "gvisor.DebugEvent")
+}
+
+func init() { proto.RegisterFile("pkg/eventchannel/event.proto", fileDescriptor_fcfbd51abd9de962) }
+
+var fileDescriptor_fcfbd51abd9de962 = []byte{
+	// 103 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0x92, 0x29, 0xc8, 0x4e, 0xd7,
+	0x4f, 0x2d, 0x4b, 0xcd, 0x2b, 0x49, 0xce, 0x48, 0xcc, 0xcb, 0x4b, 0xcd, 0x81, 0x70, 0xf4, 0x0a,
+	0x8a, 0xf2, 0x4b, 0xf2, 0x85, 0xd8, 0xd2, 0xcb, 0x32, 0x8b, 0xf3, 0x8b, 0x94, 0x4c, 0xb8, 0xb8,
+	0x5c, 0x52, 0x93, 0x4a, 0xd3, 0x5d, 0x41, 0x72, 0x42, 0x42, 0x5c, 0x2c, 0x79, 0x89, 0xb9, 0xa9,
+	0x12, 0x8c, 0x0a, 0x8c, 0x1a, 0x9c, 0x41, 0x60, 0x36, 0x48, 0xac, 0x24, 0xb5, 0xa2, 0x44, 0x82,
+	0x09, 0x22, 0x06, 0x62, 0x27, 0xb1, 0x81, 0x0d, 0x31, 0x06, 0x04, 0x00, 0x00, 0xff, 0xff, 0x17,
+	0xee, 0x7f, 0xef, 0x64, 0x00, 0x00, 0x00,
+}
diff --git a/pkg/eventchannel/eventchannel_state_autogen.go b/pkg/eventchannel/eventchannel_state_autogen.go
new file mode 100755
index 000000000..cfd3a5e43
--- /dev/null
+++ b/pkg/eventchannel/eventchannel_state_autogen.go
@@ -0,0 +1,4 @@
+// automatically generated by stateify.
+
+package eventchannel
+