exp/ssh: remove duplicated terminal code.

The terminal code in exp/terminal was forked from the code in exp/ssh.
This change removes the duplicated code from exp/ssh in favour of
using exp/terminal.

R=rsc
CC=golang-dev
https://golang.org/cl/5375064

5 files changed, 112 insertions, 416 deletions

diff --git a/src/pkg/exp/ssh/Makefile b/src/pkg/exp/ssh/Makefile
index 1b75d5aacd..9c04444327 100644
--- a/src/pkg/exp/ssh/Makefile
+++ b/src/pkg/exp/ssh/Makefile
@@ -13,7 +13,7 @@ GOFILES=\
 	common.go\
 	messages.go\
 	server.go\
-	server_shell.go\
+	server_terminal.go\
 	session.go\
 	tcpip.go\
 	transport.go\
diff --git a/src/pkg/exp/ssh/doc.go b/src/pkg/exp/ssh/doc.go
index 4ea402c5d2..e7deb5ec16 100644
--- a/src/pkg/exp/ssh/doc.go
+++ b/src/pkg/exp/ssh/doc.go
@@ -14,7 +14,7 @@ others.
 An SSH server is represented by a ServerConfig, which holds certificate
 details and handles authentication of ServerConns.
 
-	config := new(ServerConfig)
+	config := new(ssh.ServerConfig)
 	config.PubKeyCallback = pubKeyAuth
 	config.PasswordCallback = passwordAuth
 
@@ -34,8 +34,7 @@ Once a ServerConfig has been configured, connections can be accepted.
 	if err != nil {
 		panic("failed to accept incoming connection")
 	}
-	err = sConn.Handshake(conn)
-	if err != nil {
+	if err := sConn.Handshake(conn); err != nil {
 		panic("failed to handshake")
 	}
 
@@ -60,16 +59,20 @@ the case of a shell, the type is "session" and ServerShell may be used to
 present a simple terminal interface.
 
 	if channel.ChannelType() != "session" {
-		c.Reject(UnknownChannelType, "unknown channel type")
+		channel.Reject(UnknownChannelType, "unknown channel type")
 		return
 	}
 	channel.Accept()
 
-	shell := NewServerShell(channel, "> ")
+	term := terminal.NewTerminal(channel, "> ")
+	serverTerm := &ssh.ServerTerminal{
+		Term: term,
+		Channel: channel,
+	}
 	go func() {
 		defer channel.Close()
 		for {
-			line, err := shell.ReadLine()
+			line, err := serverTerm.ReadLine()
 			if err != nil {
 				break
 			}
@@ -97,7 +100,8 @@ ClientAuth via the Auth field in ClientConfig.
 		}
 	}
 
-An SSH client is represented with a ClientConn. 
+An SSH client is represented with a ClientConn. Currently only the "password"
+authentication method is supported.
 
 	config := &ClientConfig{
 		User: "username",
@@ -105,12 +109,12 @@ An SSH client is represented with a ClientConn.
 	}
 	client, err := Dial("yourserver.com:22", config)
 
-Each ClientConn can support multiple interactive sessions, represented by a Session. 
+Each ClientConn can support multiple interactive sessions, represented by a Session.
 
 	session, err := client.NewSession()
 
-Once a Session is created, you can execute a single command on the remote side 
-using the Run method.
+Once a Session is created, you can execute a single command on the remote side
+using the Exec method.
 
 	b := bytes.NewBuffer()
 	session.Stdin = b
diff --git a/src/pkg/exp/ssh/server_shell.go b/src/pkg/exp/ssh/server_shell.go
deleted file mode 100644
index 5243d0ee7f..0000000000
--- a/src/pkg/exp/ssh/server_shell.go
+++ /dev/null
@@ -1,398 +0,0 @@
-// Copyright 2011 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 ssh
-
-import "io"
-
-// ServerShell contains the state for running a VT100 terminal that is capable
-// of reading lines of input.
-type ServerShell struct {
-	c      Channel
-	prompt string
-
-	// line is the current line being entered.
-	line []byte
-	// pos is the logical position of the cursor in line
-	pos int
-
-	// cursorX contains the current X value of the cursor where the left
-	// edge is 0. cursorY contains the row number where the first row of
-	// the current line is 0.
-	cursorX, cursorY int
-	// maxLine is the greatest value of cursorY so far.
-	maxLine int
-
-	termWidth, termHeight int
-
-	// outBuf contains the terminal data to be sent.
-	outBuf []byte
-	// remainder contains the remainder of any partial key sequences after
-	// a read. It aliases into inBuf.
-	remainder []byte
-	inBuf     [256]byte
-}
-
-// NewServerShell runs a VT100 terminal on the given channel. prompt is a
-// string that is written at the start of each input line. For example: "> ".
-func NewServerShell(c Channel, prompt string) *ServerShell {
-	return &ServerShell{
-		c:          c,
-		prompt:     prompt,
-		termWidth:  80,
-		termHeight: 24,
-	}
-}
-
-const (
-	keyCtrlD     = 4
-	keyEnter     = '\r'
-	keyEscape    = 27
-	keyBackspace = 127
-	keyUnknown   = 256 + iota
-	keyUp
-	keyDown
-	keyLeft
-	keyRight
-	keyAltLeft
-	keyAltRight
-)
-
-// bytesToKey tries to parse a key sequence from b. If successful, it returns
-// the key and the remainder of the input. Otherwise it returns -1.
-func bytesToKey(b []byte) (int, []byte) {
-	if len(b) == 0 {
-		return -1, nil
-	}
-
-	if b[0] != keyEscape {
-		return int(b[0]), b[1:]
-	}
-
-	if len(b) >= 3 && b[0] == keyEscape && b[1] == '[' {
-		switch b[2] {
-		case 'A':
-			return keyUp, b[3:]
-		case 'B':
-			return keyDown, b[3:]
-		case 'C':
-			return keyRight, b[3:]
-		case 'D':
-			return keyLeft, b[3:]
-		}
-	}
-
-	if len(b) >= 6 && b[0] == keyEscape && b[1] == '[' && b[2] == '1' && b[3] == ';' && b[4] == '3' {
-		switch b[5] {
-		case 'C':
-			return keyAltRight, b[6:]
-		case 'D':
-			return keyAltLeft, b[6:]
-		}
-	}
-
-	// If we get here then we have a key that we don't recognise, or a
-	// partial sequence. It's not clear how one should find the end of a
-	// sequence without knowing them all, but it seems that [a-zA-Z] only
-	// appears at the end of a sequence.
-	for i, c := range b[0:] {
-		if c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' {
-			return keyUnknown, b[i+1:]
-		}
-	}
-
-	return -1, b
-}
-
-// queue appends data to the end of ss.outBuf
-func (ss *ServerShell) queue(data []byte) {
-	if len(ss.outBuf)+len(data) > cap(ss.outBuf) {
-		newOutBuf := make([]byte, len(ss.outBuf), 2*(len(ss.outBuf)+len(data)))
-		copy(newOutBuf, ss.outBuf)
-		ss.outBuf = newOutBuf
-	}
-
-	oldLen := len(ss.outBuf)
-	ss.outBuf = ss.outBuf[:len(ss.outBuf)+len(data)]
-	copy(ss.outBuf[oldLen:], data)
-}
-
-var eraseUnderCursor = []byte{' ', keyEscape, '[', 'D'}
-
-func isPrintable(key int) bool {
-	return key >= 32 && key < 127
-}
-
-// moveCursorToPos appends data to ss.outBuf which will move the cursor to the
-// given, logical position in the text.
-func (ss *ServerShell) moveCursorToPos(pos int) {
-	x := len(ss.prompt) + pos
-	y := x / ss.termWidth
-	x = x % ss.termWidth
-
-	up := 0
-	if y < ss.cursorY {
-		up = ss.cursorY - y
-	}
-
-	down := 0
-	if y > ss.cursorY {
-		down = y - ss.cursorY
-	}
-
-	left := 0
-	if x < ss.cursorX {
-		left = ss.cursorX - x
-	}
-
-	right := 0
-	if x > ss.cursorX {
-		right = x - ss.cursorX
-	}
-
-	movement := make([]byte, 3*(up+down+left+right))
-	m := movement
-	for i := 0; i < up; i++ {
-		m[0] = keyEscape
-		m[1] = '['
-		m[2] = 'A'
-		m = m[3:]
-	}
-	for i := 0; i < down; i++ {
-		m[0] = keyEscape
-		m[1] = '['
-		m[2] = 'B'
-		m = m[3:]
-	}
-	for i := 0; i < left; i++ {
-		m[0] = keyEscape
-		m[1] = '['
-		m[2] = 'D'
-		m = m[3:]
-	}
-	for i := 0; i < right; i++ {
-		m[0] = keyEscape
-		m[1] = '['
-		m[2] = 'C'
-		m = m[3:]
-	}
-
-	ss.cursorX = x
-	ss.cursorY = y
-	ss.queue(movement)
-}
-
-const maxLineLength = 4096
-
-// handleKey processes the given key and, optionally, returns a line of text
-// that the user has entered.
-func (ss *ServerShell) handleKey(key int) (line string, ok bool) {
-	switch key {
-	case keyBackspace:
-		if ss.pos == 0 {
-			return
-		}
-		ss.pos--
-
-		copy(ss.line[ss.pos:], ss.line[1+ss.pos:])
-		ss.line = ss.line[:len(ss.line)-1]
-		ss.writeLine(ss.line[ss.pos:])
-		ss.moveCursorToPos(ss.pos)
-		ss.queue(eraseUnderCursor)
-	case keyAltLeft:
-		// move left by a word.
-		if ss.pos == 0 {
-			return
-		}
-		ss.pos--
-		for ss.pos > 0 {
-			if ss.line[ss.pos] != ' ' {
-				break
-			}
-			ss.pos--
-		}
-		for ss.pos > 0 {
-			if ss.line[ss.pos] == ' ' {
-				ss.pos++
-				break
-			}
-			ss.pos--
-		}
-		ss.moveCursorToPos(ss.pos)
-	case keyAltRight:
-		// move right by a word.
-		for ss.pos < len(ss.line) {
-			if ss.line[ss.pos] == ' ' {
-				break
-			}
-			ss.pos++
-		}
-		for ss.pos < len(ss.line) {
-			if ss.line[ss.pos] != ' ' {
-				break
-			}
-			ss.pos++
-		}
-		ss.moveCursorToPos(ss.pos)
-	case keyLeft:
-		if ss.pos == 0 {
-			return
-		}
-		ss.pos--
-		ss.moveCursorToPos(ss.pos)
-	case keyRight:
-		if ss.pos == len(ss.line) {
-			return
-		}
-		ss.pos++
-		ss.moveCursorToPos(ss.pos)
-	case keyEnter:
-		ss.moveCursorToPos(len(ss.line))
-		ss.queue([]byte("\r\n"))
-		line = string(ss.line)
-		ok = true
-		ss.line = ss.line[:0]
-		ss.pos = 0
-		ss.cursorX = 0
-		ss.cursorY = 0
-		ss.maxLine = 0
-	default:
-		if !isPrintable(key) {
-			return
-		}
-		if len(ss.line) == maxLineLength {
-			return
-		}
-		if len(ss.line) == cap(ss.line) {
-			newLine := make([]byte, len(ss.line), 2*(1+len(ss.line)))
-			copy(newLine, ss.line)
-			ss.line = newLine
-		}
-		ss.line = ss.line[:len(ss.line)+1]
-		copy(ss.line[ss.pos+1:], ss.line[ss.pos:])
-		ss.line[ss.pos] = byte(key)
-		ss.writeLine(ss.line[ss.pos:])
-		ss.pos++
-		ss.moveCursorToPos(ss.pos)
-	}
-	return
-}
-
-func (ss *ServerShell) writeLine(line []byte) {
-	for len(line) != 0 {
-		if ss.cursorX == ss.termWidth {
-			ss.queue([]byte("\r\n"))
-			ss.cursorX = 0
-			ss.cursorY++
-			if ss.cursorY > ss.maxLine {
-				ss.maxLine = ss.cursorY
-			}
-		}
-
-		remainingOnLine := ss.termWidth - ss.cursorX
-		todo := len(line)
-		if todo > remainingOnLine {
-			todo = remainingOnLine
-		}
-		ss.queue(line[:todo])
-		ss.cursorX += todo
-		line = line[todo:]
-	}
-}
-
-// parsePtyRequest parses the payload of the pty-req message and extracts the
-// dimensions of the terminal. See RFC 4254, section 6.2.
-func parsePtyRequest(s []byte) (width, height int, ok bool) {
-	_, s, ok = parseString(s)
-	if !ok {
-		return
-	}
-	width32, s, ok := parseUint32(s)
-	if !ok {
-		return
-	}
-	height32, _, ok := parseUint32(s)
-	width = int(width32)
-	height = int(height32)
-	if width < 1 {
-		ok = false
-	}
-	if height < 1 {
-		ok = false
-	}
-	return
-}
-
-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 error) {
-	ss.writeLine([]byte(ss.prompt))
-	ss.c.Write(ss.outBuf)
-	ss.outBuf = ss.outBuf[:0]
-
-	for {
-		// ss.remainder is a slice at the beginning of ss.inBuf
-		// containing a partial key sequence
-		readBuf := ss.inBuf[len(ss.remainder):]
-		var n int
-		n, err = ss.c.Read(readBuf)
-		if err == nil {
-			ss.remainder = ss.inBuf[:n+len(ss.remainder)]
-			rest := ss.remainder
-			lineOk := false
-			for !lineOk {
-				var key int
-				key, rest = bytesToKey(rest)
-				if key < 0 {
-					break
-				}
-				if key == keyCtrlD {
-					return "", io.EOF
-				}
-				line, lineOk = ss.handleKey(key)
-			}
-			if len(rest) > 0 {
-				n := copy(ss.inBuf[:], rest)
-				ss.remainder = ss.inBuf[:n]
-			} else {
-				ss.remainder = nil
-			}
-			ss.c.Write(ss.outBuf)
-			ss.outBuf = ss.outBuf[:0]
-			if lineOk {
-				return
-			}
-			continue
-		}
-
-		if req, ok := err.(ChannelRequest); ok {
-			ok := false
-			switch req.Request {
-			case "pty-req":
-				ss.termWidth, ss.termHeight, ok = parsePtyRequest(req.Payload)
-				if !ok {
-					ss.termWidth = 80
-					ss.termHeight = 24
-				}
-			case "shell":
-				ok = true
-				if len(req.Payload) > 0 {
-					// We don't accept any commands, only the default shell.
-					ok = false
-				}
-			case "env":
-				ok = true
-			}
-			if req.WantReply {
-				ss.c.AckRequest(ok)
-			}
-		} else {
-			return "", err
-		}
-	}
-	panic("unreachable")
-}
diff --git a/src/pkg/exp/ssh/server_terminal.go b/src/pkg/exp/ssh/server_terminal.go
new file mode 100644
index 0000000000..708a9159ec
--- /dev/null
+++ b/src/pkg/exp/ssh/server_terminal.go
@@ -0,0 +1,81 @@
+// Copyright 2011 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 ssh
+
+// A Terminal is capable of parsing and generating virtual terminal
+// data from an SSH client.
+type Terminal interface {
+	ReadLine() (line string, err error)
+	SetSize(x, y int)
+	Write([]byte) (int, error)
+}
+
+// ServerTerminal contains the state for running a terminal that is capable of
+// reading lines of input.
+type ServerTerminal struct {
+	Term    Terminal
+	Channel Channel
+}
+
+// parsePtyRequest parses the payload of the pty-req message and extracts the
+// dimensions of the terminal. See RFC 4254, section 6.2.
+func parsePtyRequest(s []byte) (width, height int, ok bool) {
+	_, s, ok = parseString(s)
+	if !ok {
+		return
+	}
+	width32, s, ok := parseUint32(s)
+	if !ok {
+		return
+	}
+	height32, _, ok := parseUint32(s)
+	width = int(width32)
+	height = int(height32)
+	if width < 1 {
+		ok = false
+	}
+	if height < 1 {
+		ok = false
+	}
+	return
+}
+
+func (ss *ServerTerminal) Write(buf []byte) (n int, err error) {
+	return ss.Term.Write(buf)
+}
+
+// ReadLine returns a line of input from the terminal.
+func (ss *ServerTerminal) ReadLine() (line string, err error) {
+	for {
+		if line, err = ss.Term.ReadLine(); err == nil {
+			return
+		}
+
+		req, ok := err.(ChannelRequest)
+		if !ok {
+			return
+		}
+
+		ok = false
+		switch req.Request {
+		case "pty-req":
+			var width, height int
+			width, height, ok = parsePtyRequest(req.Payload)
+			ss.Term.SetSize(width, height)
+		case "shell":
+			ok = true
+			if len(req.Payload) > 0 {
+				// We don't accept any commands, only the default shell.
+				ok = false
+			}
+		case "env":
+			ok = true
+		}
+		if req.WantReply {
+			ss.Channel.AckRequest(ok)
+		}
+	}
+	panic("unreachable")
+}
diff --git a/src/pkg/exp/ssh/session_test.go b/src/pkg/exp/ssh/session_test.go
index 2882620b0b..4a3d22bee0 100644
--- a/src/pkg/exp/ssh/session_test.go
+++ b/src/pkg/exp/ssh/session_test.go
@@ -8,6 +8,7 @@ package ssh
 
 import (
 	"bytes"
+	"exp/terminal"
 	"io"
 	"testing"
 )
@@ -290,24 +291,32 @@ type exitSignalMsg struct {
 	Lang       string
 }
 
+func newServerShell(ch *channel, prompt string) *ServerTerminal {
+	term := terminal.NewTerminal(ch, prompt)
+	return &ServerTerminal{
+		Term:    term,
+		Channel: ch,
+	}
+}
+
 func exitStatusZeroHandler(ch *channel) {
 	defer ch.Close()
 	// this string is returned to stdout
-	shell := NewServerShell(ch, "> ")
+	shell := newServerShell(ch, "> ")
 	shell.ReadLine()
 	sendStatus(0, ch)
 }
 
 func exitStatusNonZeroHandler(ch *channel) {
 	defer ch.Close()
-	shell := NewServerShell(ch, "> ")
+	shell := newServerShell(ch, "> ")
 	shell.ReadLine()
 	sendStatus(15, ch)
 }
 
 func exitSignalAndStatusHandler(ch *channel) {
 	defer ch.Close()
-	shell := NewServerShell(ch, "> ")
+	shell := newServerShell(ch, "> ")
 	shell.ReadLine()
 	sendStatus(15, ch)
 	sendSignal("TERM", ch)
@@ -315,28 +324,28 @@ func exitSignalAndStatusHandler(ch *channel) {
 
 func exitSignalHandler(ch *channel) {
 	defer ch.Close()
-	shell := NewServerShell(ch, "> ")
+	shell := newServerShell(ch, "> ")
 	shell.ReadLine()
 	sendSignal("TERM", ch)
 }
 
 func exitSignalUnknownHandler(ch *channel) {
 	defer ch.Close()
-	shell := NewServerShell(ch, "> ")
+	shell := newServerShell(ch, "> ")
 	shell.ReadLine()
 	sendSignal("SYS", ch)
 }
 
 func exitWithoutSignalOrStatus(ch *channel) {
 	defer ch.Close()
-	shell := NewServerShell(ch, "> ")
+	shell := newServerShell(ch, "> ")
 	shell.ReadLine()
 }
 
 func shellHandler(ch *channel) {
 	defer ch.Close()
 	// this string is returned to stdout
-	shell := NewServerShell(ch, "golang")
+	shell := newServerShell(ch, "golang")
 	shell.ReadLine()
 	sendStatus(0, ch)
 }