libgo: Update to weekly.2011-11-02.

From-SVN: r181964

9 files changed, 103 insertions, 105 deletions

diff --git a/libgo/go/exp/ssh/channel.go b/libgo/go/exp/ssh/channel.go
index f69b735..6ff8203 100644
--- a/libgo/go/exp/ssh/channel.go
+++ b/libgo/go/exp/ssh/channel.go
@@ -5,7 +5,8 @@
 package ssh
 
 import (
-	"os"
+	"errors"
+	"io"
 	"sync"
 )
 
@@ -13,19 +14,19 @@ import (
 // SSH connection.
 type Channel interface {
 	// Accept accepts the channel creation request.
-	Accept() os.Error
+	Accept() error
 	// Reject rejects the channel creation request. After calling this, no
 	// other methods on the Channel may be called. If they are then the
 	// peer is likely to signal a protocol error and drop the connection.
-	Reject(reason RejectionReason, message string) os.Error
+	Reject(reason RejectionReason, message string) error
 
-	// Read may return a ChannelRequest as an os.Error.
-	Read(data []byte) (int, os.Error)
-	Write(data []byte) (int, os.Error)
-	Close() os.Error
+	// Read may return a ChannelRequest as an error.
+	Read(data []byte) (int, error)
+	Write(data []byte) (int, error)
+	Close() error
 
 	// AckRequest either sends an ack or nack to the channel request.
-	AckRequest(ok bool) os.Error
+	AckRequest(ok bool) error
 
 	// ChannelType returns the type of the channel, as supplied by the
 	// client.
@@ -43,7 +44,7 @@ type ChannelRequest struct {
 	Payload   []byte
 }
 
-func (c ChannelRequest) String() string {
+func (c ChannelRequest) Error() string {
 	return "channel request received"
 }
 
@@ -72,7 +73,7 @@ type channel struct {
 	myId, theirId         uint32
 	myWindow, theirWindow uint32
 	maxPacketSize         uint32
-	err                   os.Error
+	err                   error
 
 	pendingRequests []ChannelRequest
 	pendingData     []byte
@@ -83,7 +84,7 @@ type channel struct {
 	cond *sync.Cond
 }
 
-func (c *channel) Accept() os.Error {
+func (c *channel) Accept() error {
 	c.serverConn.lock.Lock()
 	defer c.serverConn.lock.Unlock()
 
@@ -100,7 +101,7 @@ func (c *channel) Accept() os.Error {
 	return c.serverConn.writePacket(marshal(msgChannelOpenConfirm, confirm))
 }
 
-func (c *channel) Reject(reason RejectionReason, message string) os.Error {
+func (c *channel) Reject(reason RejectionReason, message string) error {
 	c.serverConn.lock.Lock()
 	defer c.serverConn.lock.Unlock()
 
@@ -167,7 +168,7 @@ func (c *channel) handleData(data []byte) {
 	c.cond.Signal()
 }
 
-func (c *channel) Read(data []byte) (n int, err os.Error) {
+func (c *channel) Read(data []byte) (n int, err error) {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
@@ -187,7 +188,7 @@ func (c *channel) Read(data []byte) (n int, err os.Error) {
 
 	for {
 		if c.theySentEOF || c.theyClosed || c.dead {
-			return 0, os.EOF
+			return 0, io.EOF
 		}
 
 		if len(c.pendingRequests) > 0 {
@@ -223,11 +224,11 @@ func (c *channel) Read(data []byte) (n int, err os.Error) {
 	panic("unreachable")
 }
 
-func (c *channel) Write(data []byte) (n int, err os.Error) {
+func (c *channel) Write(data []byte) (n int, err error) {
 	for len(data) > 0 {
 		c.lock.Lock()
 		if c.dead || c.weClosed {
-			return 0, os.EOF
+			return 0, io.EOF
 		}
 
 		if c.theirWindow == 0 {
@@ -267,7 +268,7 @@ func (c *channel) Write(data []byte) (n int, err os.Error) {
 	return
 }
 
-func (c *channel) Close() os.Error {
+func (c *channel) Close() error {
 	c.serverConn.lock.Lock()
 	defer c.serverConn.lock.Unlock()
 
@@ -276,7 +277,7 @@ func (c *channel) Close() os.Error {
 	}
 
 	if c.weClosed {
-		return os.NewError("ssh: channel already closed")
+		return errors.New("ssh: channel already closed")
 	}
 	c.weClosed = true
 
@@ -286,7 +287,7 @@ func (c *channel) Close() os.Error {
 	return c.serverConn.writePacket(marshal(msgChannelClose, closeMsg))
 }
 
-func (c *channel) AckRequest(ok bool) os.Error {
+func (c *channel) AckRequest(ok bool) error {
 	c.serverConn.lock.Lock()
 	defer c.serverConn.lock.Unlock()
 
diff --git a/libgo/go/exp/ssh/client.go b/libgo/go/exp/ssh/client.go
index 9eed315..345e707 100644
--- a/libgo/go/exp/ssh/client.go
+++ b/libgo/go/exp/ssh/client.go
@@ -8,10 +8,10 @@ import (
 	"big"
 	"crypto"
 	"crypto/rand"
+	"errors"
 	"fmt"
 	"io"
 	"net"
-	"os"
 	"sync"
 )
 
@@ -26,7 +26,7 @@ type ClientConn struct {
 }
 
 // Client returns a new SSH client connection using c as the underlying transport.
-func Client(c net.Conn, config *ClientConfig) (*ClientConn, os.Error) {
+func Client(c net.Conn, config *ClientConfig) (*ClientConn, error) {
 	conn := &ClientConn{
 		transport: newTransport(c, config.rand()),
 		config:    config,
@@ -44,7 +44,7 @@ func Client(c net.Conn, config *ClientConfig) (*ClientConn, os.Error) {
 }
 
 // handshake performs the client side key exchange. See RFC 4253 Section 7.
-func (c *ClientConn) handshake() os.Error {
+func (c *ClientConn) handshake() error {
 	var magics handshakeMagics
 
 	if _, err := c.Write(clientVersion); err != nil {
@@ -91,7 +91,7 @@ func (c *ClientConn) handshake() os.Error {
 
 	kexAlgo, hostKeyAlgo, ok := findAgreedAlgorithms(c.transport, &clientKexInit, &serverKexInit)
 	if !ok {
-		return os.NewError("ssh: no common algorithms")
+		return errors.New("ssh: no common algorithms")
 	}
 
 	if serverKexInit.FirstKexFollows && kexAlgo != serverKexInit.KexAlgos[0] {
@@ -133,7 +133,7 @@ func (c *ClientConn) handshake() os.Error {
 
 // authenticate authenticates with the remote server. See RFC 4252. 
 // Only "password" authentication is supported.
-func (c *ClientConn) authenticate() os.Error {
+func (c *ClientConn) authenticate() error {
 	if err := c.writePacket(marshal(msgServiceRequest, serviceRequestMsg{serviceUserAuth})); err != nil {
 		return err
 	}
@@ -166,7 +166,7 @@ func (c *ClientConn) authenticate() os.Error {
 	return nil
 }
 
-func (c *ClientConn) sendUserAuthReq(method string) os.Error {
+func (c *ClientConn) sendUserAuthReq(method string) error {
 	length := stringLength([]byte(c.config.Password)) + 1
 	payload := make([]byte, length)
 	// always false for password auth, see RFC 4252 Section 8.
@@ -183,7 +183,7 @@ func (c *ClientConn) sendUserAuthReq(method string) os.Error {
 
 // kexDH performs Diffie-Hellman key agreement on a ClientConn. The
 // returned values are given the same names as in RFC 4253, section 8.
-func (c *ClientConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handshakeMagics, hostKeyAlgo string) ([]byte, []byte, os.Error) {
+func (c *ClientConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handshakeMagics, hostKeyAlgo string) ([]byte, []byte, error) {
 	x, err := rand.Int(c.config.rand(), group.p)
 	if err != nil {
 		return nil, nil, err
@@ -207,7 +207,7 @@ func (c *ClientConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handsha
 	}
 
 	if kexDHReply.Y.Sign() == 0 || kexDHReply.Y.Cmp(group.p) >= 0 {
-		return nil, nil, os.NewError("server DH parameter out of bounds")
+		return nil, nil, errors.New("server DH parameter out of bounds")
 	}
 
 	kInt := new(big.Int).Exp(kexDHReply.Y, x, group.p)
@@ -230,7 +230,7 @@ func (c *ClientConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handsha
 
 // openChan opens a new client channel. The most common session type is "session". 
 // The full set of valid session types are listed in RFC 4250 4.9.1.
-func (c *ClientConn) openChan(typ string) (*clientChan, os.Error) {
+func (c *ClientConn) openChan(typ string) (*clientChan, error) {
 	ch := c.newChan(c.transport)
 	if err := c.writePacket(marshal(msgChannelOpen, channelOpenMsg{
 		ChanType:      typ,
@@ -247,10 +247,10 @@ func (c *ClientConn) openChan(typ string) (*clientChan, os.Error) {
 		ch.peersId = msg.MyId
 	case *channelOpenFailureMsg:
 		c.chanlist.remove(ch.id)
-		return nil, os.NewError(msg.Message)
+		return nil, errors.New(msg.Message)
 	default:
 		c.chanlist.remove(ch.id)
-		return nil, os.NewError("Unexpected packet")
+		return nil, errors.New("Unexpected packet")
 	}
 	return ch, nil
 }
@@ -329,7 +329,7 @@ func (c *ClientConn) mainLoop() {
 
 // Dial connects to the given network address using net.Dial and 
 // then initiates a SSH handshake, returning the resulting client connection.
-func Dial(network, addr string, config *ClientConfig) (*ClientConn, os.Error) {
+func Dial(network, addr string, config *ClientConfig) (*ClientConn, error) {
 	conn, err := net.Dial(network, addr)
 	if err != nil {
 		return nil, err
@@ -382,13 +382,13 @@ func newClientChan(t *transport, id uint32) *clientChan {
 }
 
 // Close closes the channel. This does not close the underlying connection.
-func (c *clientChan) Close() os.Error {
+func (c *clientChan) Close() error {
 	return c.writePacket(marshal(msgChannelClose, channelCloseMsg{
 		PeersId: c.id,
 	}))
 }
 
-func (c *clientChan) sendChanReq(req channelRequestMsg) os.Error {
+func (c *clientChan) sendChanReq(req channelRequestMsg) error {
 	if err := c.writePacket(marshal(msgChannelRequest, req)); err != nil {
 		return err
 	}
@@ -447,12 +447,12 @@ type chanWriter struct {
 }
 
 // Write writes data to the remote process's standard input.
-func (w *chanWriter) Write(data []byte) (n int, err os.Error) {
+func (w *chanWriter) Write(data []byte) (n int, err error) {
 	for {
 		if w.rwin == 0 {
 			win, ok := <-w.win
 			if !ok {
-				return 0, os.EOF
+				return 0, io.EOF
 			}
 			w.rwin += win
 			continue
@@ -469,7 +469,7 @@ func (w *chanWriter) Write(data []byte) (n int, err os.Error) {
 	panic("unreachable")
 }
 
-func (w *chanWriter) Close() os.Error {
+func (w *chanWriter) Close() error {
 	return w.writePacket(marshal(msgChannelEOF, channelEOFMsg{w.id}))
 }
 
@@ -485,7 +485,7 @@ type chanReader struct {
 }
 
 // Read reads data from the remote process's stdout or stderr.
-func (r *chanReader) Read(data []byte) (int, os.Error) {
+func (r *chanReader) Read(data []byte) (int, error) {
 	var ok bool
 	for {
 		if len(r.buf) > 0 {
@@ -499,12 +499,12 @@ func (r *chanReader) Read(data []byte) (int, os.Error) {
 		}
 		r.buf, ok = <-r.data
 		if !ok {
-			return 0, os.EOF
+			return 0, io.EOF
 		}
 	}
 	panic("unreachable")
 }
 
-func (r *chanReader) Close() os.Error {
+func (r *chanReader) Close() error {
 	return r.writePacket(marshal(msgChannelEOF, channelEOFMsg{r.id}))
 }
diff --git a/libgo/go/exp/ssh/common.go b/libgo/go/exp/ssh/common.go
index 739bd2f..f68c353 100644
--- a/libgo/go/exp/ssh/common.go
+++ b/libgo/go/exp/ssh/common.go
@@ -53,7 +53,7 @@ type UnexpectedMessageError struct {
 	expected, got uint8
 }
 
-func (u UnexpectedMessageError) String() string {
+func (u UnexpectedMessageError) Error() string {
 	return "ssh: unexpected message type " + strconv.Itoa(int(u.got)) + " (expected " + strconv.Itoa(int(u.expected)) + ")"
 }
 
@@ -62,7 +62,7 @@ type ParseError struct {
 	msgType uint8
 }
 
-func (p ParseError) String() string {
+func (p ParseError) Error() string {
 	return "ssh: parse error in message type " + strconv.Itoa(int(p.msgType))
 }
 
diff --git a/libgo/go/exp/ssh/messages.go b/libgo/go/exp/ssh/messages.go
index 5f2c447..5eae181 100644
--- a/libgo/go/exp/ssh/messages.go
+++ b/libgo/go/exp/ssh/messages.go
@@ -8,7 +8,6 @@ import (
 	"big"
 	"bytes"
 	"io"
-	"os"
 	"reflect"
 )
 
@@ -192,7 +191,7 @@ type userAuthPubKeyOkMsg struct {
 // unmarshal parses the SSH wire data in packet into out using reflection.
 // expectedType is the expected SSH message type. It either returns nil on
 // success, or a ParseError or UnexpectedMessageError on error.
-func unmarshal(out interface{}, packet []byte, expectedType uint8) os.Error {
+func unmarshal(out interface{}, packet []byte, expectedType uint8) error {
 	if len(packet) == 0 {
 		return ParseError{expectedType}
 	}
diff --git a/libgo/go/exp/ssh/server.go b/libgo/go/exp/ssh/server.go
index 0dd24ec..2ae8079 100644
--- a/libgo/go/exp/ssh/server.go
+++ b/libgo/go/exp/ssh/server.go
@@ -12,9 +12,9 @@ import (
 	"crypto/rsa"
 	"crypto/x509"
 	"encoding/pem"
+	"errors"
 	"io"
 	"net"
-	"os"
 	"sync"
 )
 
@@ -53,12 +53,12 @@ func (c *ServerConfig) rand() io.Reader {
 // private key configured in order to accept connections. The private key must
 // be in the form of a PEM encoded, PKCS#1, RSA private key. The file "id_rsa"
 // typically contains such a key.
-func (s *ServerConfig) SetRSAPrivateKey(pemBytes []byte) os.Error {
+func (s *ServerConfig) SetRSAPrivateKey(pemBytes []byte) error {
 	block, _ := pem.Decode(pemBytes)
 	if block == nil {
-		return os.NewError("ssh: no key found")
+		return errors.New("ssh: no key found")
 	}
-	var err os.Error
+	var err error
 	s.rsa, err = x509.ParsePKCS1PrivateKey(block.Bytes)
 	if err != nil {
 		return err
@@ -140,7 +140,7 @@ type ServerConn struct {
 	// lock protects err and also allows Channels to serialise their writes
 	// to out.
 	lock sync.RWMutex
-	err  os.Error
+	err  error
 
 	// cachedPubKeys contains the cache results of tests for public keys.
 	// Since SSH clients will query whether a public key is acceptable
@@ -162,7 +162,7 @@ func Server(c net.Conn, config *ServerConfig) *ServerConn {
 
 // kexDH performs Diffie-Hellman key agreement on a ServerConnection. The
 // returned values are given the same names as in RFC 4253, section 8.
-func (s *ServerConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handshakeMagics, hostKeyAlgo string) (H, K []byte, err os.Error) {
+func (s *ServerConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handshakeMagics, hostKeyAlgo string) (H, K []byte, err error) {
 	packet, err := s.readPacket()
 	if err != nil {
 		return
@@ -173,7 +173,7 @@ func (s *ServerConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handsha
 	}
 
 	if kexDHInit.X.Sign() == 0 || kexDHInit.X.Cmp(group.p) >= 0 {
-		return nil, nil, os.NewError("client DH parameter out of bounds")
+		return nil, nil, errors.New("client DH parameter out of bounds")
 	}
 
 	y, err := rand.Int(s.config.rand(), group.p)
@@ -189,7 +189,7 @@ func (s *ServerConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handsha
 	case hostAlgoRSA:
 		serializedHostKey = s.config.rsaSerialized
 	default:
-		return nil, nil, os.NewError("internal error")
+		return nil, nil, errors.New("internal error")
 	}
 
 	h := hashFunc.New()
@@ -218,7 +218,7 @@ func (s *ServerConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handsha
 			return
 		}
 	default:
-		return nil, nil, os.NewError("internal error")
+		return nil, nil, errors.New("internal error")
 	}
 
 	serializedSig := serializeRSASignature(sig)
@@ -279,7 +279,7 @@ func buildDataSignedForAuth(sessionId []byte, req userAuthRequestMsg, algo, pubK
 }
 
 // Handshake performs an SSH transport and client authentication on the given ServerConn.
-func (s *ServerConn) Handshake() os.Error {
+func (s *ServerConn) Handshake() error {
 	var magics handshakeMagics
 	if _, err := s.Write(serverVersion); err != nil {
 		return err
@@ -326,7 +326,7 @@ func (s *ServerConn) Handshake() os.Error {
 
 	kexAlgo, hostKeyAlgo, ok := findAgreedAlgorithms(s.transport, &clientKexInit, &serverKexInit)
 	if !ok {
-		return os.NewError("ssh: no common algorithms")
+		return errors.New("ssh: no common algorithms")
 	}
 
 	if clientKexInit.FirstKexFollows && kexAlgo != clientKexInit.KexAlgos[0] {
@@ -345,7 +345,7 @@ func (s *ServerConn) Handshake() os.Error {
 		dhGroup14Once.Do(initDHGroup14)
 		H, K, err = s.kexDH(dhGroup14, hashFunc, &magics, hostKeyAlgo)
 	default:
-		err = os.NewError("ssh: unexpected key exchange algorithm " + kexAlgo)
+		err = errors.New("ssh: unexpected key exchange algorithm " + kexAlgo)
 	}
 	if err != nil {
 		return err
@@ -374,7 +374,7 @@ func (s *ServerConn) Handshake() os.Error {
 		return err
 	}
 	if serviceRequest.Service != serviceUserAuth {
-		return os.NewError("ssh: requested service '" + serviceRequest.Service + "' before authenticating")
+		return errors.New("ssh: requested service '" + serviceRequest.Service + "' before authenticating")
 	}
 	serviceAccept := serviceAcceptMsg{
 		Service: serviceUserAuth,
@@ -420,9 +420,9 @@ func (s *ServerConn) testPubKey(user, algo string, pubKey []byte) bool {
 	return result
 }
 
-func (s *ServerConn) authenticate(H []byte) os.Error {
+func (s *ServerConn) authenticate(H []byte) error {
 	var userAuthReq userAuthRequestMsg
-	var err os.Error
+	var err error
 	var packet []byte
 
 userAuthLoop:
@@ -435,7 +435,7 @@ userAuthLoop:
 		}
 
 		if userAuthReq.Service != serviceSSH {
-			return os.NewError("ssh: client attempted to negotiate for unknown service: " + userAuthReq.Service)
+			return errors.New("ssh: client attempted to negotiate for unknown service: " + userAuthReq.Service)
 		}
 
 		switch userAuthReq.Method {
@@ -523,7 +523,7 @@ userAuthLoop:
 						return ParseError{msgUserAuthRequest}
 					}
 				default:
-					return os.NewError("ssh: isAcceptableAlgo incorrect")
+					return errors.New("ssh: isAcceptableAlgo incorrect")
 				}
 				if s.testPubKey(userAuthReq.User, algo, pubKey) {
 					break userAuthLoop
@@ -540,7 +540,7 @@ userAuthLoop:
 		}
 
 		if len(failureMsg.Methods) == 0 {
-			return os.NewError("ssh: no authentication methods configured but NoClientAuth is also false")
+			return errors.New("ssh: no authentication methods configured but NoClientAuth is also false")
 		}
 
 		if err = s.writePacket(marshal(msgUserAuthFailure, failureMsg)); err != nil {
@@ -560,7 +560,7 @@ const defaultWindowSize = 32768
 
 // Accept reads and processes messages on a ServerConn. It must be called
 // in order to demultiplex messages to any resulting Channels.
-func (s *ServerConn) Accept() (Channel, os.Error) {
+func (s *ServerConn) Accept() (Channel, error) {
 	if s.err != nil {
 		return nil, s.err
 	}
@@ -660,7 +660,7 @@ func (s *ServerConn) Accept() (Channel, os.Error) {
 			case UnexpectedMessageError:
 				return nil, msg
 			case *disconnectMsg:
-				return nil, os.EOF
+				return nil, io.EOF
 			default:
 				// Unknown message. Ignore.
 			}
@@ -679,7 +679,7 @@ type Listener struct {
 // Accept waits for and returns the next incoming SSH connection.
 // The receiver should call Handshake() in another goroutine 
 // to avoid blocking the accepter.
-func (l *Listener) Accept() (*ServerConn, os.Error) {
+func (l *Listener) Accept() (*ServerConn, error) {
 	c, err := l.listener.Accept()
 	if err != nil {
 		return nil, err
@@ -694,13 +694,13 @@ func (l *Listener) Addr() net.Addr {
 }
 
 // Close closes the listener.
-func (l *Listener) Close() os.Error {
+func (l *Listener) Close() error {
 	return l.listener.Close()
 }
 
 // Listen creates an SSH listener accepting connections on
 // the given network address using net.Listen.
-func Listen(network, addr string, config *ServerConfig) (*Listener, os.Error) {
+func Listen(network, addr string, config *ServerConfig) (*Listener, error) {
 	l, err := net.Listen(network, addr)
 	if err != nil {
 		return nil, err
diff --git a/libgo/go/exp/ssh/server_shell.go b/libgo/go/exp/ssh/server_shell.go
index 0e9967a..5243d0e 100644
--- a/libgo/go/exp/ssh/server_shell.go
+++ b/libgo/go/exp/ssh/server_shell.go
@@ -4,9 +4,7 @@
 
 package ssh
 
-import (
-	"os"
-)
+import "io"
 
 // ServerShell contains the state for running a VT100 terminal that is capable
 // of reading lines of input.
@@ -326,12 +324,12 @@ func parsePtyRequest(s []byte) (width, height int, ok bool) {
 	return
 }
 
-func (ss *ServerShell) Write(buf []byte) (n int, err os.Error) {
+func (ss *ServerShell) Write(buf []byte) (n int, err error) {
 	return ss.c.Write(buf)
 }
 
 // ReadLine returns a line of input from the terminal.
-func (ss *ServerShell) ReadLine() (line string, err os.Error) {
+func (ss *ServerShell) ReadLine() (line string, err error) {
 	ss.writeLine([]byte(ss.prompt))
 	ss.c.Write(ss.outBuf)
 	ss.outBuf = ss.outBuf[:0]
@@ -353,7 +351,7 @@ func (ss *ServerShell) ReadLine() (line string, err os.Error) {
 					break
 				}
 				if key == keyCtrlD {
-					return "", os.EOF
+					return "", io.EOF
 				}
 				line, lineOk = ss.handleKey(key)
 			}
diff --git a/libgo/go/exp/ssh/server_shell_test.go b/libgo/go/exp/ssh/server_shell_test.go
index 622cf7c..aa69ef7 100644
--- a/libgo/go/exp/ssh/server_shell_test.go
+++ b/libgo/go/exp/ssh/server_shell_test.go
@@ -5,8 +5,8 @@
 package ssh
 
 import (
+	"io"
 	"testing"
-	"os"
 )
 
 type MockChannel struct {
@@ -15,15 +15,15 @@ type MockChannel struct {
 	received     []byte
 }
 
-func (c *MockChannel) Accept() os.Error {
+func (c *MockChannel) Accept() error {
 	return nil
 }
 
-func (c *MockChannel) Reject(RejectionReason, string) os.Error {
+func (c *MockChannel) Reject(RejectionReason, string) error {
 	return nil
 }
 
-func (c *MockChannel) Read(data []byte) (n int, err os.Error) {
+func (c *MockChannel) Read(data []byte) (n int, err error) {
 	n = len(data)
 	if n == 0 {
 		return
@@ -32,7 +32,7 @@ func (c *MockChannel) Read(data []byte) (n int, err os.Error) {
 		n = len(c.toSend)
 	}
 	if n == 0 {
-		return 0, os.EOF
+		return 0, io.EOF
 	}
 	if c.bytesPerRead > 0 && n > c.bytesPerRead {
 		n = c.bytesPerRead
@@ -42,16 +42,16 @@ func (c *MockChannel) Read(data []byte) (n int, err os.Error) {
 	return
 }
 
-func (c *MockChannel) Write(data []byte) (n int, err os.Error) {
+func (c *MockChannel) Write(data []byte) (n int, err error) {
 	c.received = append(c.received, data...)
 	return len(data), nil
 }
 
-func (c *MockChannel) Close() os.Error {
+func (c *MockChannel) Close() error {
 	return nil
 }
 
-func (c *MockChannel) AckRequest(ok bool) os.Error {
+func (c *MockChannel) AckRequest(ok bool) error {
 	return nil
 }
 
@@ -70,7 +70,7 @@ func TestClose(t *testing.T) {
 	if line != "" {
 		t.Errorf("Expected empty line but got: %s", line)
 	}
-	if err != os.EOF {
+	if err != io.EOF {
 		t.Errorf("Error should have been EOF but got: %s", err)
 	}
 }
@@ -78,12 +78,12 @@ func TestClose(t *testing.T) {
 var keyPressTests = []struct {
 	in   string
 	line string
-	err  os.Error
+	err  error
 }{
 	{
 		"",
 		"",
-		os.EOF,
+		io.EOF,
 	},
 	{
 		"\r",
diff --git a/libgo/go/exp/ssh/session.go b/libgo/go/exp/ssh/session.go
index 13df2f0..77154f2 100644
--- a/libgo/go/exp/ssh/session.go
+++ b/libgo/go/exp/ssh/session.go
@@ -9,8 +9,8 @@ package ssh
 
 import (
 	"encoding/binary"
+	"errors"
 	"io"
-	"os"
 )
 
 // A Session represents a connection to a remote command or shell.
@@ -34,7 +34,7 @@ type Session struct {
 
 // Setenv sets an environment variable that will be applied to any
 // command executed by Shell or Exec.
-func (s *Session) Setenv(name, value string) os.Error {
+func (s *Session) Setenv(name, value string) error {
 	n, v := []byte(name), []byte(value)
 	nlen, vlen := stringLength(n), stringLength(v)
 	payload := make([]byte, nlen+vlen)
@@ -53,7 +53,7 @@ func (s *Session) Setenv(name, value string) os.Error {
 var emptyModeList = []byte{0, 0, 0, 1, 0}
 
 // RequestPty requests the association of a pty with the session on the remote host.
-func (s *Session) RequestPty(term string, h, w int) os.Error {
+func (s *Session) RequestPty(term string, h, w int) error {
 	buf := make([]byte, 4+len(term)+16+len(emptyModeList))
 	b := marshalString(buf, []byte(term))
 	binary.BigEndian.PutUint32(b, uint32(h))
@@ -73,9 +73,9 @@ func (s *Session) RequestPty(term string, h, w int) os.Error {
 // Exec runs cmd on the remote host. Typically, the remote 
 // server passes cmd to the shell for interpretation. 
 // A Session only accepts one call to Exec or Shell.
-func (s *Session) Exec(cmd string) os.Error {
+func (s *Session) Exec(cmd string) error {
 	if s.started {
-		return os.NewError("session already started")
+		return errors.New("session already started")
 	}
 	cmdLen := stringLength([]byte(cmd))
 	payload := make([]byte, cmdLen)
@@ -92,9 +92,9 @@ func (s *Session) Exec(cmd string) os.Error {
 
 // Shell starts a login shell on the remote host. A Session only 
 // accepts one call to Exec or Shell.
-func (s *Session) Shell() os.Error {
+func (s *Session) Shell() error {
 	if s.started {
-		return os.NewError("session already started")
+		return errors.New("session already started")
 	}
 	s.started = true
 
@@ -106,7 +106,7 @@ func (s *Session) Shell() os.Error {
 }
 
 // NewSession returns a new interactive session on the remote host.
-func (c *ClientConn) NewSession() (*Session, os.Error) {
+func (c *ClientConn) NewSession() (*Session, error) {
 	ch, err := c.openChan("session")
 	if err != nil {
 		return nil, err
diff --git a/libgo/go/exp/ssh/transport.go b/libgo/go/exp/ssh/transport.go
index 97eaf97..579a9d8 100644
--- a/libgo/go/exp/ssh/transport.go
+++ b/libgo/go/exp/ssh/transport.go
@@ -11,10 +11,10 @@ import (
 	"crypto/cipher"
 	"crypto/hmac"
 	"crypto/subtle"
+	"errors"
 	"hash"
 	"io"
 	"net"
-	"os"
 	"sync"
 )
 
@@ -27,7 +27,7 @@ const (
 // TODO(dfc) suggestions for a better name will be warmly received.
 type filteredConn interface {
 	// Close closes the connection.
-	Close() os.Error
+	Close() error
 
 	// LocalAddr returns the local network address.
 	LocalAddr() net.Addr
@@ -40,7 +40,7 @@ type filteredConn interface {
 // an SSH peer.
 type packetWriter interface {
 	// Encrypt and send a packet of data to the remote peer.
-	writePacket(packet []byte) os.Error
+	writePacket(packet []byte) error
 }
 
 // transport represents the SSH connection to the remote peer.
@@ -79,7 +79,7 @@ type common struct {
 }
 
 // Read and decrypt a single packet from the remote peer.
-func (r *reader) readOnePacket() ([]byte, os.Error) {
+func (r *reader) readOnePacket() ([]byte, error) {
 	var lengthBytes = make([]byte, 5)
 	var macSize uint32
 
@@ -108,10 +108,10 @@ func (r *reader) readOnePacket() ([]byte, os.Error) {
 	paddingLength := uint32(lengthBytes[4])
 
 	if length <= paddingLength+1 {
-		return nil, os.NewError("invalid packet length")
+		return nil, errors.New("invalid packet length")
 	}
 	if length > maxPacketSize {
-		return nil, os.NewError("packet too large")
+		return nil, errors.New("packet too large")
 	}
 
 	packet := make([]byte, length-1+macSize)
@@ -126,7 +126,7 @@ func (r *reader) readOnePacket() ([]byte, os.Error) {
 	if r.mac != nil {
 		r.mac.Write(packet[:length-1])
 		if subtle.ConstantTimeCompare(r.mac.Sum(), mac) != 1 {
-			return nil, os.NewError("ssh: MAC failure")
+			return nil, errors.New("ssh: MAC failure")
 		}
 	}
 
@@ -135,7 +135,7 @@ func (r *reader) readOnePacket() ([]byte, os.Error) {
 }
 
 // Read and decrypt next packet discarding debug and noop messages.
-func (t *transport) readPacket() ([]byte, os.Error) {
+func (t *transport) readPacket() ([]byte, error) {
 	for {
 		packet, err := t.readOnePacket()
 		if err != nil {
@@ -149,7 +149,7 @@ func (t *transport) readPacket() ([]byte, os.Error) {
 }
 
 // Encrypt and send a packet of data to the remote peer.
-func (w *writer) writePacket(packet []byte) os.Error {
+func (w *writer) writePacket(packet []byte) error {
 	w.Mutex.Lock()
 	defer w.Mutex.Unlock()
 
@@ -218,7 +218,7 @@ func (w *writer) writePacket(packet []byte) os.Error {
 }
 
 // Send a message to the remote peer
-func (t *transport) sendMessage(typ uint8, msg interface{}) os.Error {
+func (t *transport) sendMessage(typ uint8, msg interface{}) error {
 	packet := marshal(typ, msg)
 	return t.writePacket(packet)
 }
@@ -252,7 +252,7 @@ var (
 // setupKeys sets the cipher and MAC keys from K, H and sessionId, as
 // described in RFC 4253, section 6.4. direction should either be serverKeys
 // (to setup server->client keys) or clientKeys (for client->server keys).
-func (c *common) setupKeys(d direction, K, H, sessionId []byte, hashFunc crypto.Hash) os.Error {
+func (c *common) setupKeys(d direction, K, H, sessionId []byte, hashFunc crypto.Hash) error {
 	h := hashFunc.New()
 
 	blockSize := 16
@@ -308,7 +308,7 @@ type truncatingMAC struct {
 	hmac   hash.Hash
 }
 
-func (t truncatingMAC) Write(data []byte) (int, os.Error) {
+func (t truncatingMAC) Write(data []byte) (int, error) {
 	return t.hmac.Write(data)
 }
 
@@ -332,7 +332,7 @@ func (t truncatingMAC) Size() int {
 const maxVersionStringBytes = 1024
 
 // Read version string as specified by RFC 4253, section 4.2.
-func readVersion(r io.Reader) ([]byte, os.Error) {
+func readVersion(r io.Reader) ([]byte, error) {
 	versionString := make([]byte, 0, 64)
 	var ok, seenCR bool
 	var buf [1]byte
@@ -360,7 +360,7 @@ forEachByte:
 	}
 
 	if !ok {
-		return nil, os.NewError("failed to read version string")
+		return nil, errors.New("failed to read version string")
 	}
 
 	// We need to remove the CR from versionString