obtained gcc-4.6.4.tar.bz2 from upstream website;upstream

verified gcc-4.6.4.tar.bz2.sig;
imported gcc-4.6.4 source tree from verified upstream tarball.

downloading a git-generated archive based on the 'upstream' tag
should provide you with a source tree that is binary identical
to the one extracted from the above tarball.

if you have obtained the source via the command 'git clone',
however, do note that line-endings of files in your working
directory might differ from line-endings of the respective
files in the upstream repository.

4 files changed, 1473 insertions, 0 deletions

diff --git a/libgo/go/netchan/common.go b/libgo/go/netchan/common.go
new file mode 100644
index 000000000..56c0b2519
--- /dev/null
+++ b/libgo/go/netchan/common.go
@@ -0,0 +1,325 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package netchan
+
+import (
+	"gob"
+	"net"
+	"os"
+	"reflect"
+	"sync"
+	"time"
+)
+
+// The direction of a connection from the client's perspective.
+type Dir int
+
+const (
+	Recv Dir = iota
+	Send
+)
+
+func (dir Dir) String() string {
+	switch dir {
+	case Recv:
+		return "Recv"
+	case Send:
+		return "Send"
+	}
+	return "???"
+}
+
+// Payload types
+const (
+	payRequest = iota // request structure follows
+	payError          // error structure follows
+	payData           // user payload follows
+	payAck            // acknowledgement; no payload
+	payClosed         // channel is now closed
+	payAckSend        // payload has been delivered.
+)
+
+// A header is sent as a prefix to every transmission.  It will be followed by
+// a request structure, an error structure, or an arbitrary user payload structure.
+type header struct {
+	Id          int
+	PayloadType int
+	SeqNum      int64
+}
+
+// Sent with a header once per channel from importer to exporter to report
+// that it wants to bind to a channel with the specified direction for count
+// messages, with space for size buffered values. If count is -1, it means unlimited.
+type request struct {
+	Name  string
+	Count int64
+	Size  int
+	Dir   Dir
+}
+
+// Sent with a header to report an error.
+type error struct {
+	Error string
+}
+
+// Used to unify management of acknowledgements for import and export.
+type unackedCounter interface {
+	unackedCount() int64
+	ack() int64
+	seq() int64
+}
+
+// A channel and its direction.
+type chanDir struct {
+	ch  *reflect.ChanValue
+	dir Dir
+}
+
+// clientSet contains the objects and methods needed for tracking
+// clients of an exporter and draining outstanding messages.
+type clientSet struct {
+	mu      sync.Mutex // protects access to channel and client maps
+	names   map[string]*chanDir
+	clients map[unackedCounter]bool
+}
+
+// Mutex-protected encoder and decoder pair.
+type encDec struct {
+	decLock sync.Mutex
+	dec     *gob.Decoder
+	encLock sync.Mutex
+	enc     *gob.Encoder
+}
+
+func newEncDec(conn net.Conn) *encDec {
+	return &encDec{
+		dec: gob.NewDecoder(conn),
+		enc: gob.NewEncoder(conn),
+	}
+}
+
+// Decode an item from the connection.
+func (ed *encDec) decode(value reflect.Value) os.Error {
+	ed.decLock.Lock()
+	err := ed.dec.DecodeValue(value)
+	if err != nil {
+		// TODO: tear down connection?
+	}
+	ed.decLock.Unlock()
+	return err
+}
+
+// Encode a header and payload onto the connection.
+func (ed *encDec) encode(hdr *header, payloadType int, payload interface{}) os.Error {
+	ed.encLock.Lock()
+	hdr.PayloadType = payloadType
+	err := ed.enc.Encode(hdr)
+	if err == nil {
+		if payload != nil {
+			err = ed.enc.Encode(payload)
+		}
+	}
+	if err != nil {
+		// TODO: tear down connection if there is an error?
+	}
+	ed.encLock.Unlock()
+	return err
+}
+
+// See the comment for Exporter.Drain.
+func (cs *clientSet) drain(timeout int64) os.Error {
+	startTime := time.Nanoseconds()
+	for {
+		pending := false
+		cs.mu.Lock()
+		// Any messages waiting for a client?
+		for _, chDir := range cs.names {
+			if chDir.ch.Len() > 0 {
+				pending = true
+			}
+		}
+		// Any unacknowledged messages?
+		for client := range cs.clients {
+			n := client.unackedCount()
+			if n > 0 { // Check for > rather than != just to be safe.
+				pending = true
+				break
+			}
+		}
+		cs.mu.Unlock()
+		if !pending {
+			break
+		}
+		if timeout > 0 && time.Nanoseconds()-startTime >= timeout {
+			return os.ErrorString("timeout")
+		}
+		time.Sleep(100 * 1e6) // 100 milliseconds
+	}
+	return nil
+}
+
+// See the comment for Exporter.Sync.
+func (cs *clientSet) sync(timeout int64) os.Error {
+	startTime := time.Nanoseconds()
+	// seq remembers the clients and their seqNum at point of entry.
+	seq := make(map[unackedCounter]int64)
+	for client := range cs.clients {
+		seq[client] = client.seq()
+	}
+	for {
+		pending := false
+		cs.mu.Lock()
+		// Any unacknowledged messages?  Look only at clients that existed
+		// when we started and are still in this client set.
+		for client := range seq {
+			if _, ok := cs.clients[client]; ok {
+				if client.ack() < seq[client] {
+					pending = true
+					break
+				}
+			}
+		}
+		cs.mu.Unlock()
+		if !pending {
+			break
+		}
+		if timeout > 0 && time.Nanoseconds()-startTime >= timeout {
+			return os.ErrorString("timeout")
+		}
+		time.Sleep(100 * 1e6) // 100 milliseconds
+	}
+	return nil
+}
+
+// A netChan represents a channel imported or exported
+// on a single connection. Flow is controlled by the receiving
+// side by sending payAckSend messages when values
+// are delivered into the local channel.
+type netChan struct {
+	*chanDir
+	name string
+	id   int
+	size int // buffer size of channel.
+
+	// sender-specific state
+	ackCh chan bool // buffered with space for all the acks we need
+	space int       // available space.
+
+	// receiver-specific state
+	sendCh chan reflect.Value // buffered channel of values received from other end.
+	ed     *encDec            // so that we can send acks.
+	count  int64              // number of values still to receive.
+}
+
+// Create a new netChan with the given name (only used for
+// messages), id, direction, buffer size, and count.
+// The connection to the other side is represented by ed.
+func newNetChan(name string, id int, ch *chanDir, ed *encDec, size int, count int64) *netChan {
+	c := &netChan{chanDir: ch, name: name, id: id, size: size, ed: ed, count: count}
+	if c.dir == Send {
+		c.ackCh = make(chan bool, size)
+		c.space = size
+	}
+	return c
+}
+
+// Close the channel.
+func (nch *netChan) close() {
+	if nch.dir == Recv {
+		if nch.sendCh != nil {
+			// If the sender goroutine is active, close the channel to it.
+			// It will close nch.ch when it can.
+			close(nch.sendCh)
+		} else {
+			nch.ch.Close()
+		}
+	} else {
+		nch.ch.Close()
+		close(nch.ackCh)
+	}
+}
+
+// Send message from remote side to local receiver.
+func (nch *netChan) send(val reflect.Value) {
+	if nch.dir != Recv {
+		panic("send on wrong direction of channel")
+	}
+	if nch.sendCh == nil {
+		// If possible, do local send directly and ack immediately.
+		if nch.ch.TrySend(val) {
+			nch.sendAck()
+			return
+		}
+		// Start sender goroutine to manage delayed delivery of values.
+		nch.sendCh = make(chan reflect.Value, nch.size)
+		go nch.sender()
+	}
+	if ok := nch.sendCh <- val; !ok {
+		// TODO: should this be more resilient?
+		panic("netchan: remote sender sent more values than allowed")
+	}
+}
+
+// sendAck sends an acknowledgment that a message has left
+// the channel's buffer. If the messages remaining to be sent
+// will fit in the channel's buffer, then we don't
+// need to send an ack.
+func (nch *netChan) sendAck() {
+	if nch.count < 0 || nch.count > int64(nch.size) {
+		nch.ed.encode(&header{Id: nch.id}, payAckSend, nil)
+	}
+	if nch.count > 0 {
+		nch.count--
+	}
+}
+
+// The sender process forwards items from the sending queue
+// to the destination channel, acknowledging each item.
+func (nch *netChan) sender() {
+	if nch.dir != Recv {
+		panic("sender on wrong direction of channel")
+	}
+	// When Exporter.Hangup is called, the underlying channel is closed,
+	// and so we may get a "too many operations on closed channel" error
+	// if there are outstanding messages in sendCh.
+	// Make sure that this doesn't panic the whole program.
+	defer func() {
+		if r := recover(); r != nil {
+			// TODO check that r is "too many operations", otherwise re-panic.
+		}
+	}()
+	for v := range nch.sendCh {
+		nch.ch.Send(v)
+		nch.sendAck()
+	}
+	nch.ch.Close()
+}
+
+// Receive value from local side for sending to remote side.
+func (nch *netChan) recv() (val reflect.Value, closed bool) {
+	if nch.dir != Send {
+		panic("recv on wrong direction of channel")
+	}
+
+	if nch.space == 0 {
+		// Wait for buffer space.
+		<-nch.ackCh
+		nch.space++
+	}
+	nch.space--
+	return nch.ch.Recv(), nch.ch.Closed()
+}
+
+// acked is called when the remote side indicates that
+// a value has been delivered.
+func (nch *netChan) acked() {
+	if nch.dir != Send {
+		panic("recv on wrong direction of channel")
+	}
+	if ok := nch.ackCh <- true; !ok {
+		panic("netchan: remote receiver sent too many acks")
+		// TODO: should this be more resilient?
+	}
+}
diff --git a/libgo/go/netchan/export.go b/libgo/go/netchan/export.go
new file mode 100644
index 000000000..0f72ca7a9
--- /dev/null
+++ b/libgo/go/netchan/export.go
@@ -0,0 +1,390 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+	The netchan package implements type-safe networked channels:
+	it allows the two ends of a channel to appear on different
+	computers connected by a network.  It does this by transporting
+	data sent to a channel on one machine so it can be recovered
+	by a receive of a channel of the same type on the other.
+
+	An exporter publishes a set of channels by name.  An importer
+	connects to the exporting machine and imports the channels
+	by name. After importing the channels, the two machines can
+	use the channels in the usual way.
+
+	Networked channels are not synchronized; they always behave
+	as if they are buffered channels of at least one element.
+*/
+package netchan
+
+// BUG: can't use range clause to receive when using ImportNValues to limit the count.
+
+import (
+	"log"
+	"net"
+	"os"
+	"reflect"
+	"strconv"
+	"sync"
+)
+
+// Export
+
+// expLog is a logging convenience function.  The first argument must be a string.
+func expLog(args ...interface{}) {
+	args[0] = "netchan export: " + args[0].(string)
+	log.Print(args...)
+}
+
+// An Exporter allows a set of channels to be published on a single
+// network port.  A single machine may have multiple Exporters
+// but they must use different ports.
+type Exporter struct {
+	*clientSet
+	listener net.Listener
+}
+
+type expClient struct {
+	*encDec
+	exp     *Exporter
+	chans   map[int]*netChan // channels in use by client
+	mu      sync.Mutex       // protects remaining fields
+	errored bool             // client has been sent an error
+	seqNum  int64            // sequences messages sent to client; has value of highest sent
+	ackNum  int64            // highest sequence number acknowledged
+	seqLock sync.Mutex       // guarantees messages are in sequence, only locked under mu
+}
+
+func newClient(exp *Exporter, conn net.Conn) *expClient {
+	client := new(expClient)
+	client.exp = exp
+	client.encDec = newEncDec(conn)
+	client.seqNum = 0
+	client.ackNum = 0
+	client.chans = make(map[int]*netChan)
+	return client
+}
+
+func (client *expClient) sendError(hdr *header, err string) {
+	error := &error{err}
+	expLog("sending error to client:", error.Error)
+	client.encode(hdr, payError, error) // ignore any encode error, hope client gets it
+	client.mu.Lock()
+	client.errored = true
+	client.mu.Unlock()
+}
+
+func (client *expClient) newChan(hdr *header, dir Dir, name string, size int, count int64) *netChan {
+	exp := client.exp
+	exp.mu.Lock()
+	ech, ok := exp.names[name]
+	exp.mu.Unlock()
+	if !ok {
+		client.sendError(hdr, "no such channel: "+name)
+		return nil
+	}
+	if ech.dir != dir {
+		client.sendError(hdr, "wrong direction for channel: "+name)
+		return nil
+	}
+	nch := newNetChan(name, hdr.Id, ech, client.encDec, size, count)
+	client.chans[hdr.Id] = nch
+	return nch
+}
+
+func (client *expClient) getChan(hdr *header, dir Dir) *netChan {
+	nch := client.chans[hdr.Id]
+	if nch == nil {
+		return nil
+	}
+	if nch.dir != dir {
+		client.sendError(hdr, "wrong direction for channel: "+nch.name)
+	}
+	return nch
+}
+
+// The function run manages sends and receives for a single client.  For each
+// (client Recv) request, this will launch a serveRecv goroutine to deliver
+// the data for that channel, while (client Send) requests are handled as
+// data arrives from the client.
+func (client *expClient) run() {
+	hdr := new(header)
+	hdrValue := reflect.NewValue(hdr)
+	req := new(request)
+	reqValue := reflect.NewValue(req)
+	error := new(error)
+	for {
+		*hdr = header{}
+		if err := client.decode(hdrValue); err != nil {
+			expLog("error decoding client header:", err)
+			break
+		}
+		switch hdr.PayloadType {
+		case payRequest:
+			*req = request{}
+			if err := client.decode(reqValue); err != nil {
+				expLog("error decoding client request:", err)
+				break
+			}
+			if req.Size < 1 {
+				panic("netchan: remote requested " + strconv.Itoa(req.Size) + " values")
+			}
+			switch req.Dir {
+			case Recv:
+				// look up channel before calling serveRecv to
+				// avoid a lock around client.chans.
+				if nch := client.newChan(hdr, Send, req.Name, req.Size, req.Count); nch != nil {
+					go client.serveRecv(nch, *hdr, req.Count)
+				}
+			case Send:
+				client.newChan(hdr, Recv, req.Name, req.Size, req.Count)
+				// The actual sends will have payload type payData.
+				// TODO: manage the count?
+			default:
+				error.Error = "request: can't handle channel direction"
+				expLog(error.Error, req.Dir)
+				client.encode(hdr, payError, error)
+			}
+		case payData:
+			client.serveSend(*hdr)
+		case payClosed:
+			client.serveClosed(*hdr)
+		case payAck:
+			client.mu.Lock()
+			if client.ackNum != hdr.SeqNum-1 {
+				// Since the sequence number is incremented and the message is sent
+				// in a single instance of locking client.mu, the messages are guaranteed
+				// to be sent in order.  Therefore receipt of acknowledgement N means
+				// all messages <=N have been seen by the recipient.  We check anyway.
+				expLog("sequence out of order:", client.ackNum, hdr.SeqNum)
+			}
+			if client.ackNum < hdr.SeqNum { // If there has been an error, don't back up the count. 
+				client.ackNum = hdr.SeqNum
+			}
+			client.mu.Unlock()
+		case payAckSend:
+			if nch := client.getChan(hdr, Send); nch != nil {
+				nch.acked()
+			}
+		default:
+			log.Exit("netchan export: unknown payload type", hdr.PayloadType)
+		}
+	}
+	client.exp.delClient(client)
+}
+
+// Send all the data on a single channel to a client asking for a Recv.
+// The header is passed by value to avoid issues of overwriting.
+func (client *expClient) serveRecv(nch *netChan, hdr header, count int64) {
+	for {
+		val, closed := nch.recv()
+		if closed {
+			if err := client.encode(&hdr, payClosed, nil); err != nil {
+				expLog("error encoding server closed message:", err)
+			}
+			break
+		}
+		// We hold the lock during transmission to guarantee messages are
+		// sent in sequence number order.  Also, we increment first so the
+		// value of client.SeqNum is the value of the highest used sequence
+		// number, not one beyond.
+		client.mu.Lock()
+		client.seqNum++
+		hdr.SeqNum = client.seqNum
+		client.seqLock.Lock() // guarantee ordering of messages
+		client.mu.Unlock()
+		err := client.encode(&hdr, payData, val.Interface())
+		client.seqLock.Unlock()
+		if err != nil {
+			expLog("error encoding client response:", err)
+			client.sendError(&hdr, err.String())
+			break
+		}
+		// Negative count means run forever.
+		if count >= 0 {
+			if count--; count <= 0 {
+				break
+			}
+		}
+	}
+}
+
+// Receive and deliver locally one item from a client asking for a Send
+// The header is passed by value to avoid issues of overwriting.
+func (client *expClient) serveSend(hdr header) {
+	nch := client.getChan(&hdr, Recv)
+	if nch == nil {
+		return
+	}
+	// Create a new value for each received item.
+	val := reflect.MakeZero(nch.ch.Type().(*reflect.ChanType).Elem())
+	if err := client.decode(val); err != nil {
+		expLog("value decode:", err, "; type ", nch.ch.Type())
+		return
+	}
+	nch.send(val)
+}
+
+// Report that client has closed the channel that is sending to us.
+// The header is passed by value to avoid issues of overwriting.
+func (client *expClient) serveClosed(hdr header) {
+	nch := client.getChan(&hdr, Recv)
+	if nch == nil {
+		return
+	}
+	nch.close()
+}
+
+func (client *expClient) unackedCount() int64 {
+	client.mu.Lock()
+	n := client.seqNum - client.ackNum
+	client.mu.Unlock()
+	return n
+}
+
+func (client *expClient) seq() int64 {
+	client.mu.Lock()
+	n := client.seqNum
+	client.mu.Unlock()
+	return n
+}
+
+func (client *expClient) ack() int64 {
+	client.mu.Lock()
+	n := client.seqNum
+	client.mu.Unlock()
+	return n
+}
+
+// Wait for incoming connections, start a new runner for each
+func (exp *Exporter) listen() {
+	for {
+		conn, err := exp.listener.Accept()
+		if err != nil {
+			expLog("listen:", err)
+			break
+		}
+		client := exp.addClient(conn)
+		go client.run()
+	}
+}
+
+// NewExporter creates a new Exporter to export channels
+// on the network and local address defined as in net.Listen.
+func NewExporter(network, localaddr string) (*Exporter, os.Error) {
+	listener, err := net.Listen(network, localaddr)
+	if err != nil {
+		return nil, err
+	}
+	e := &Exporter{
+		listener: listener,
+		clientSet: &clientSet{
+			names:   make(map[string]*chanDir),
+			clients: make(map[unackedCounter]bool),
+		},
+	}
+	go e.listen()
+	return e, nil
+}
+
+// addClient creates a new expClient and records its existence
+func (exp *Exporter) addClient(conn net.Conn) *expClient {
+	client := newClient(exp, conn)
+	exp.mu.Lock()
+	exp.clients[client] = true
+	exp.mu.Unlock()
+	return client
+}
+
+// delClient forgets the client existed
+func (exp *Exporter) delClient(client *expClient) {
+	exp.mu.Lock()
+	exp.clients[client] = false, false
+	exp.mu.Unlock()
+}
+
+// Drain waits until all messages sent from this exporter/importer, including
+// those not yet sent to any client and possibly including those sent while
+// Drain was executing, have been received by the importer.  In short, it
+// waits until all the exporter's messages have been received by a client.
+// If the timeout (measured in nanoseconds) is positive and Drain takes
+// longer than that to complete, an error is returned.
+func (exp *Exporter) Drain(timeout int64) os.Error {
+	// This wrapper function is here so the method's comment will appear in godoc.
+	return exp.clientSet.drain(timeout)
+}
+
+// Sync waits until all clients of the exporter have received the messages
+// that were sent at the time Sync was invoked.  Unlike Drain, it does not
+// wait for messages sent while it is running or messages that have not been
+// dispatched to any client.  If the timeout (measured in nanoseconds) is
+// positive and Sync takes longer than that to complete, an error is
+// returned.
+func (exp *Exporter) Sync(timeout int64) os.Error {
+	// This wrapper function is here so the method's comment will appear in godoc.
+	return exp.clientSet.sync(timeout)
+}
+
+// Addr returns the Exporter's local network address.
+func (exp *Exporter) Addr() net.Addr { return exp.listener.Addr() }
+
+func checkChan(chT interface{}, dir Dir) (*reflect.ChanValue, os.Error) {
+	chanType, ok := reflect.Typeof(chT).(*reflect.ChanType)
+	if !ok {
+		return nil, os.ErrorString("not a channel")
+	}
+	if dir != Send && dir != Recv {
+		return nil, os.ErrorString("unknown channel direction")
+	}
+	switch chanType.Dir() {
+	case reflect.BothDir:
+	case reflect.SendDir:
+		if dir != Recv {
+			return nil, os.ErrorString("to import/export with Send, must provide <-chan")
+		}
+	case reflect.RecvDir:
+		if dir != Send {
+			return nil, os.ErrorString("to import/export with Recv, must provide chan<-")
+		}
+	}
+	return reflect.NewValue(chT).(*reflect.ChanValue), nil
+}
+
+// Export exports a channel of a given type and specified direction.  The
+// channel to be exported is provided in the call and may be of arbitrary
+// channel type.
+// Despite the literal signature, the effective signature is
+//	Export(name string, chT chan T, dir Dir)
+func (exp *Exporter) Export(name string, chT interface{}, dir Dir) os.Error {
+	ch, err := checkChan(chT, dir)
+	if err != nil {
+		return err
+	}
+	exp.mu.Lock()
+	defer exp.mu.Unlock()
+	_, present := exp.names[name]
+	if present {
+		return os.ErrorString("channel name already being exported:" + name)
+	}
+	exp.names[name] = &chanDir{ch, dir}
+	return nil
+}
+
+// Hangup disassociates the named channel from the Exporter and closes
+// the channel.  Messages in flight for the channel may be dropped.
+func (exp *Exporter) Hangup(name string) os.Error {
+	exp.mu.Lock()
+	chDir, ok := exp.names[name]
+	if ok {
+		exp.names[name] = nil, false
+	}
+	// TODO drop all instances of channel from client sets
+	exp.mu.Unlock()
+	if !ok {
+		return os.ErrorString("netchan export: hangup: no such channel: " + name)
+	}
+	chDir.ch.Close()
+	return nil
+}
diff --git a/libgo/go/netchan/import.go b/libgo/go/netchan/import.go
new file mode 100644
index 000000000..22b0f69ba
--- /dev/null
+++ b/libgo/go/netchan/import.go
@@ -0,0 +1,243 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package netchan
+
+import (
+	"log"
+	"net"
+	"os"
+	"reflect"
+	"sync"
+)
+
+// Import
+
+// impLog is a logging convenience function.  The first argument must be a string.
+func impLog(args ...interface{}) {
+	args[0] = "netchan import: " + args[0].(string)
+	log.Print(args...)
+}
+
+// An Importer allows a set of channels to be imported from a single
+// remote machine/network port.  A machine may have multiple
+// importers, even from the same machine/network port.
+type Importer struct {
+	*encDec
+	conn     net.Conn
+	chanLock sync.Mutex // protects access to channel map
+	names    map[string]*netChan
+	chans    map[int]*netChan
+	errors   chan os.Error
+	maxId    int
+}
+
+// NewImporter creates a new Importer object to import channels
+// from an Exporter at the network and remote address as defined in net.Dial.
+// The Exporter must be available and serving when the Importer is
+// created.
+func NewImporter(network, remoteaddr string) (*Importer, os.Error) {
+	conn, err := net.Dial(network, "", remoteaddr)
+	if err != nil {
+		return nil, err
+	}
+	imp := new(Importer)
+	imp.encDec = newEncDec(conn)
+	imp.conn = conn
+	imp.chans = make(map[int]*netChan)
+	imp.names = make(map[string]*netChan)
+	imp.errors = make(chan os.Error, 10)
+	go imp.run()
+	return imp, nil
+}
+
+// shutdown closes all channels for which we are receiving data from the remote side.
+func (imp *Importer) shutdown() {
+	imp.chanLock.Lock()
+	for _, ich := range imp.chans {
+		if ich.dir == Recv {
+			ich.close()
+		}
+	}
+	imp.chanLock.Unlock()
+}
+
+// Handle the data from a single imported data stream, which will
+// have the form
+//	(response, data)*
+// The response identifies by name which channel is transmitting data.
+func (imp *Importer) run() {
+	// Loop on responses; requests are sent by ImportNValues()
+	hdr := new(header)
+	hdrValue := reflect.NewValue(hdr)
+	ackHdr := new(header)
+	err := new(error)
+	errValue := reflect.NewValue(err)
+	for {
+		*hdr = header{}
+		if e := imp.decode(hdrValue); e != nil {
+			impLog("header:", e)
+			imp.shutdown()
+			return
+		}
+		switch hdr.PayloadType {
+		case payData:
+			// done lower in loop
+		case payError:
+			if e := imp.decode(errValue); e != nil {
+				impLog("error:", e)
+				return
+			}
+			if err.Error != "" {
+				impLog("response error:", err.Error)
+				if sent := imp.errors <- os.ErrorString(err.Error); !sent {
+					imp.shutdown()
+					return
+				}
+				continue // errors are not acknowledged.
+			}
+		case payClosed:
+			nch := imp.getChan(hdr.Id, false)
+			if nch != nil {
+				nch.close()
+			}
+			continue // closes are not acknowledged.
+		case payAckSend:
+			// we can receive spurious acks if the channel is
+			// hung up, so we ask getChan to ignore any errors.
+			nch := imp.getChan(hdr.Id, true)
+			if nch != nil {
+				nch.acked()
+			}
+			continue
+		default:
+			impLog("unexpected payload type:", hdr.PayloadType)
+			return
+		}
+		nch := imp.getChan(hdr.Id, false)
+		if nch == nil {
+			continue
+		}
+		if nch.dir != Recv {
+			impLog("cannot happen: receive from non-Recv channel")
+			return
+		}
+		// Acknowledge receipt
+		ackHdr.Id = hdr.Id
+		ackHdr.SeqNum = hdr.SeqNum
+		imp.encode(ackHdr, payAck, nil)
+		// Create a new value for each received item.
+		value := reflect.MakeZero(nch.ch.Type().(*reflect.ChanType).Elem())
+		if e := imp.decode(value); e != nil {
+			impLog("importer value decode:", e)
+			return
+		}
+		nch.send(value)
+	}
+}
+
+func (imp *Importer) getChan(id int, errOk bool) *netChan {
+	imp.chanLock.Lock()
+	ich := imp.chans[id]
+	imp.chanLock.Unlock()
+	if ich == nil {
+		if !errOk {
+			impLog("unknown id in netchan request: ", id)
+		}
+		return nil
+	}
+	return ich
+}
+
+// Errors returns a channel from which transmission and protocol errors
+// can be read. Clients of the importer are not required to read the error
+// channel for correct execution. However, if too many errors occur
+// without being read from the error channel, the importer will shut down.
+func (imp *Importer) Errors() chan os.Error {
+	return imp.errors
+}
+
+// Import imports a channel of the given type, size and specified direction.
+// It is equivalent to ImportNValues with a count of -1, meaning unbounded.
+func (imp *Importer) Import(name string, chT interface{}, dir Dir, size int) os.Error {
+	return imp.ImportNValues(name, chT, dir, size, -1)
+}
+
+// ImportNValues imports a channel of the given type and specified
+// direction and then receives or transmits up to n values on that
+// channel.  A value of n==-1 implies an unbounded number of values.  The
+// channel will have buffer space for size values, or 1 value if size < 1.
+// The channel to be bound to the remote site's channel is provided
+// in the call and may be of arbitrary channel type.
+// Despite the literal signature, the effective signature is
+//	ImportNValues(name string, chT chan T, dir Dir, n int) os.Error
+// Example usage:
+//	imp, err := NewImporter("tcp", "netchanserver.mydomain.com:1234")
+//	if err != nil { log.Exit(err) }
+//	ch := make(chan myType)
+//	err = imp.ImportNValues("name", ch, Recv, 1)
+//	if err != nil { log.Exit(err) }
+//	fmt.Printf("%+v\n", <-ch)
+func (imp *Importer) ImportNValues(name string, chT interface{}, dir Dir, size, n int) os.Error {
+	ch, err := checkChan(chT, dir)
+	if err != nil {
+		return err
+	}
+	imp.chanLock.Lock()
+	defer imp.chanLock.Unlock()
+	_, present := imp.names[name]
+	if present {
+		return os.ErrorString("channel name already being imported:" + name)
+	}
+	if size < 1 {
+		size = 1
+	}
+	id := imp.maxId
+	imp.maxId++
+	nch := newNetChan(name, id, &chanDir{ch, dir}, imp.encDec, size, int64(n))
+	imp.names[name] = nch
+	imp.chans[id] = nch
+	// Tell the other side about this channel.
+	hdr := &header{Id: id}
+	req := &request{Name: name, Count: int64(n), Dir: dir, Size: size}
+	if err = imp.encode(hdr, payRequest, req); err != nil {
+		impLog("request encode:", err)
+		return err
+	}
+	if dir == Send {
+		go func() {
+			for i := 0; n == -1 || i < n; i++ {
+				val, closed := nch.recv()
+				if closed {
+					if err = imp.encode(hdr, payClosed, nil); err != nil {
+						impLog("error encoding client closed message:", err)
+					}
+					return
+				}
+				if err = imp.encode(hdr, payData, val.Interface()); err != nil {
+					impLog("error encoding client send:", err)
+					return
+				}
+			}
+		}()
+	}
+	return nil
+}
+
+// Hangup disassociates the named channel from the Importer and closes
+// the channel.  Messages in flight for the channel may be dropped.
+func (imp *Importer) Hangup(name string) os.Error {
+	imp.chanLock.Lock()
+	nc, ok := imp.names[name]
+	if ok {
+		imp.names[name] = nil, false
+		imp.chans[nc.id] = nil, false
+	}
+	imp.chanLock.Unlock()
+	if !ok {
+		return os.ErrorString("netchan import: hangup: no such channel: " + name)
+	}
+	nc.close()
+	return nil
+}
diff --git a/libgo/go/netchan/netchan_test.go b/libgo/go/netchan/netchan_test.go
new file mode 100644
index 000000000..6d7d63f98
--- /dev/null
+++ b/libgo/go/netchan/netchan_test.go
@@ -0,0 +1,515 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package netchan
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+const count = 10     // number of items in most tests
+const closeCount = 5 // number of items when sender closes early
+
+const base = 23
+
+func exportSend(exp *Exporter, n int, t *testing.T, done chan bool) {
+	ch := make(chan int)
+	err := exp.Export("exportedSend", ch, Send)
+	if err != nil {
+		t.Fatal("exportSend:", err)
+	}
+	go func() {
+		for i := 0; i < n; i++ {
+			ch <- base+i
+		}
+		close(ch)
+		if done != nil {
+			done <- true
+		}
+	}()
+}
+
+func exportReceive(exp *Exporter, t *testing.T, expDone chan bool) {
+	ch := make(chan int)
+	err := exp.Export("exportedRecv", ch, Recv)
+	expDone <- true
+	if err != nil {
+		t.Fatal("exportReceive:", err)
+	}
+	for i := 0; i < count; i++ {
+		v := <-ch
+		if closed(ch) {
+			if i != closeCount {
+				t.Errorf("exportReceive expected close at %d; got one at %d", closeCount, i)
+			}
+			break
+		}
+		if v != base+i {
+			t.Errorf("export Receive: bad value: expected %d+%d=%d; got %d", base, i, base+i, v)
+		}
+	}
+}
+
+func importSend(imp *Importer, n int, t *testing.T, done chan bool) {
+	ch := make(chan int)
+	err := imp.ImportNValues("exportedRecv", ch, Send, 3, -1)
+	if err != nil {
+		t.Fatal("importSend:", err)
+	}
+	go func() {
+		for i := 0; i < n; i++ {
+			ch <- base+i
+		}
+		close(ch)
+		if done != nil {
+			done <- true
+		}
+	}()
+}
+
+func importReceive(imp *Importer, t *testing.T, done chan bool) {
+	ch := make(chan int)
+	err := imp.ImportNValues("exportedSend", ch, Recv, 3, count)
+	if err != nil {
+		t.Fatal("importReceive:", err)
+	}
+	for i := 0; i < count; i++ {
+		v := <-ch
+		if closed(ch) {
+			if i != closeCount {
+				t.Errorf("importReceive expected close at %d; got one at %d", closeCount, i)
+			}
+			break
+		}
+		if v != base+i {
+			t.Errorf("importReceive: bad value: expected %d+%d=%d; got %+d", base, i, base+i, v)
+		}
+	}
+	if done != nil {
+		done <- true
+	}
+}
+
+func TestExportSendImportReceive(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	exportSend(exp, count, t, nil)
+	importReceive(imp, t, nil)
+}
+
+func TestExportReceiveImportSend(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	expDone := make(chan bool)
+	done := make(chan bool)
+	go func() {
+		exportReceive(exp, t, expDone)
+		done <- true
+	}()
+	<-expDone
+	importSend(imp, count, t, nil)
+	<-done
+}
+
+func TestClosingExportSendImportReceive(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	exportSend(exp, closeCount, t, nil)
+	importReceive(imp, t, nil)
+}
+
+func TestClosingImportSendExportReceive(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	expDone := make(chan bool)
+	done := make(chan bool)
+	go func() {
+		exportReceive(exp, t, expDone)
+		done <- true
+	}()
+	<-expDone
+	importSend(imp, closeCount, t, nil)
+	<-done
+}
+
+func TestErrorForIllegalChannel(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	// Now export a channel.
+	ch := make(chan int, 1)
+	err = exp.Export("aChannel", ch, Send)
+	if err != nil {
+		t.Fatal("export:", err)
+	}
+	ch <- 1234
+	close(ch)
+	// Now try to import a different channel.
+	ch = make(chan int)
+	err = imp.Import("notAChannel", ch, Recv, 1)
+	if err != nil {
+		t.Fatal("import:", err)
+	}
+	// Expect an error now.  Start a timeout.
+	timeout := make(chan bool, 1) // buffered so closure will not hang around.
+	go func() {
+		time.Sleep(10e9) // very long, to give even really slow machines a chance.
+		timeout <- true
+	}()
+	select {
+	case err = <-imp.Errors():
+		if strings.Index(err.String(), "no such channel") < 0 {
+			t.Error("wrong error for nonexistent channel:", err)
+		}
+	case <-timeout:
+		t.Error("import of nonexistent channel did not receive an error")
+	}
+}
+
+// Not a great test but it does at least invoke Drain.
+func TestExportDrain(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	done := make(chan bool)
+	go func() {
+		exportSend(exp, closeCount, t, nil)
+		done <- true
+	}()
+	<-done
+	go importReceive(imp, t, done)
+	exp.Drain(0)
+	<-done
+}
+
+// Not a great test but it does at least invoke Sync.
+func TestExportSync(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	done := make(chan bool)
+	exportSend(exp, closeCount, t, nil)
+	go importReceive(imp, t, done)
+	exp.Sync(0)
+	<-done
+}
+
+// Test hanging up the send side of an export.
+// TODO: test hanging up the receive side of an export.
+func TestExportHangup(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	ech := make(chan int)
+	err = exp.Export("exportedSend", ech, Send)
+	if err != nil {
+		t.Fatal("export:", err)
+	}
+	// Prepare to receive two values. We'll actually deliver only one.
+	ich := make(chan int)
+	err = imp.ImportNValues("exportedSend", ich, Recv, 1, 2)
+	if err != nil {
+		t.Fatal("import exportedSend:", err)
+	}
+	// Send one value, receive it.
+	const Value = 1234
+	ech <- Value
+	v := <-ich
+	if v != Value {
+		t.Fatal("expected", Value, "got", v)
+	}
+	// Now hang up the channel.  Importer should see it close.
+	exp.Hangup("exportedSend")
+	v = <-ich
+	if !closed(ich) {
+		t.Fatal("expected channel to be closed; got value", v)
+	}
+}
+
+// Test hanging up the send side of an import.
+// TODO: test hanging up the receive side of an import.
+func TestImportHangup(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+	ech := make(chan int)
+	err = exp.Export("exportedRecv", ech, Recv)
+	if err != nil {
+		t.Fatal("export:", err)
+	}
+	// Prepare to Send two values. We'll actually deliver only one.
+	ich := make(chan int)
+	err = imp.ImportNValues("exportedRecv", ich, Send, 1, 2)
+	if err != nil {
+		t.Fatal("import exportedRecv:", err)
+	}
+	// Send one value, receive it.
+	const Value = 1234
+	ich <- Value
+	v := <-ech
+	if v != Value {
+		t.Fatal("expected", Value, "got", v)
+	}
+	// Now hang up the channel.  Exporter should see it close.
+	imp.Hangup("exportedRecv")
+	v = <-ech
+	if !closed(ech) {
+		t.Fatal("expected channel to be closed; got value", v)
+	}
+}
+
+// loop back exportedRecv to exportedSend,
+// but receive a value from ctlch before starting the loop.
+func exportLoopback(exp *Exporter, t *testing.T) {
+	inch := make(chan int)
+	if err := exp.Export("exportedRecv", inch, Recv); err != nil {
+		t.Fatal("exportRecv")
+	}
+
+	outch := make(chan int)
+	if err := exp.Export("exportedSend", outch, Send); err != nil {
+		t.Fatal("exportSend")
+	}
+
+	ctlch := make(chan int)
+	if err := exp.Export("exportedCtl", ctlch, Recv); err != nil {
+		t.Fatal("exportRecv")
+	}
+
+	go func() {
+		<-ctlch
+		for i := 0; i < count; i++ {
+			x := <-inch
+			if x != base+i {
+				t.Errorf("exportLoopback expected %d; got %d", i, x)
+			}
+			outch <- x
+		}
+	}()
+}
+
+// This test checks that channel operations can proceed
+// even when other concurrent operations are blocked.
+func TestIndependentSends(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+
+	exportLoopback(exp, t)
+
+	importSend(imp, count, t, nil)
+	done := make(chan bool)
+	go importReceive(imp, t, done)
+
+	// wait for export side to try to deliver some values.
+	time.Sleep(0.25e9)
+
+	ctlch := make(chan int)
+	if err := imp.ImportNValues("exportedCtl", ctlch, Send, 1, 1); err != nil {
+		t.Fatal("importSend:", err)
+	}
+	ctlch <- 0
+
+	<-done
+}
+
+// This test cross-connects a pair of exporter/importer pairs.
+type value struct {
+	I      int
+	Source string
+}
+
+func TestCrossConnect(t *testing.T) {
+	e1, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	i1, err := NewImporter("tcp", e1.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+
+	e2, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	i2, err := NewImporter("tcp", e2.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+
+	crossExport(e1, e2, t)
+	crossImport(i1, i2, t)
+}
+
+// Export side of cross-traffic.
+func crossExport(e1, e2 *Exporter, t *testing.T) {
+	s := make(chan value)
+	err := e1.Export("exportedSend", s, Send)
+	if err != nil {
+		t.Fatal("exportSend:", err)
+	}
+
+	r := make(chan value)
+	err = e2.Export("exportedReceive", r, Recv)
+	if err != nil {
+		t.Fatal("exportReceive:", err)
+	}
+
+	go crossLoop("export", s, r, t)
+}
+
+// Import side of cross-traffic.
+func crossImport(i1, i2 *Importer, t *testing.T) {
+	s := make(chan value)
+	err := i2.Import("exportedReceive", s, Send, 2)
+	if err != nil {
+		t.Fatal("import of exportedReceive:", err)
+	}
+
+	r := make(chan value)
+	err = i1.Import("exportedSend", r, Recv, 2)
+	if err != nil {
+		t.Fatal("import of exported Send:", err)
+	}
+
+	crossLoop("import", s, r, t)
+}
+
+// Cross-traffic: send and receive 'count' numbers.
+func crossLoop(name string, s, r chan value, t *testing.T) {
+	for si, ri := 0, 0; si < count && ri < count; {
+		select {
+		case s <- value{si, name}:
+			si++
+		case v := <-r:
+			if v.I != ri {
+				t.Errorf("loop: bad value: expected %d, hello; got %+v", ri, v)
+			}
+			ri++
+		}
+	}
+}
+
+const flowCount = 100
+
+// test flow control from exporter to importer.
+func TestExportFlowControl(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+
+	sendDone := make(chan bool, 1)
+	exportSend(exp, flowCount, t, sendDone)
+
+	ch := make(chan int)
+	err = imp.ImportNValues("exportedSend", ch, Recv, 20, -1)
+	if err != nil {
+		t.Fatal("importReceive:", err)
+	}
+
+	testFlow(sendDone, ch, flowCount, t)
+}
+
+// test flow control from importer to exporter.
+func TestImportFlowControl(t *testing.T) {
+	exp, err := NewExporter("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("new exporter:", err)
+	}
+	imp, err := NewImporter("tcp", exp.Addr().String())
+	if err != nil {
+		t.Fatal("new importer:", err)
+	}
+
+	ch := make(chan int)
+	err = exp.Export("exportedRecv", ch, Recv)
+	if err != nil {
+		t.Fatal("importReceive:", err)
+	}
+
+	sendDone := make(chan bool, 1)
+	importSend(imp, flowCount, t, sendDone)
+	testFlow(sendDone, ch, flowCount, t)
+}
+
+func testFlow(sendDone chan bool, ch <-chan int, N int, t *testing.T) {
+	go func() {
+		time.Sleep(1e9)
+		sendDone <- false
+	}()
+
+	if <-sendDone {
+		t.Fatal("send did not block")
+	}
+	n := 0
+	for i := range ch {
+		t.Log("after blocking, got value ", i)
+		n++
+	}
+	if n != N {
+		t.Fatalf("expected %d values; got %d", N, n)
+	}
+}