feat: support windows conpty

Author: aymanbagabas

go.mod

@@ -1,6 +1,8 @@
 module github.com/charmbracelet/ssh
 
-go 1.17
+go 1.21
+
+toolchain go1.21.5
 
 require (
 	github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be
@@ -10,3 +12,5 @@ require (
 )
 
 require golang.org/x/sys v0.16.0
+
+require github.com/charmbracelet/x/term v0.0.0-20240109162103-b354873f6f2c

go.sum

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"errors"
 	"io"
+	"os/exec"
 )
 
 // ErrUnsupported is returned when the platform does not support PTY.
@@ -59,3 +60,12 @@ func (rw readWriterDelegate) Read(p []byte) (n int, err error) {
 func (rw readWriterDelegate) Write(p []byte) (n int, err error) {
 	return rw.w.Write(p)
 }
+
+// Start starts a *exec.Cmd attached to the Session. If a PTY is allocated,
+// it will use that for I/O.
+// On Windows, the process execution lifecycle is not managed by Go and has to
+// be managed manually. This means that c.Wait() won't work.
+// See https://github.com/charmbracelet/x/blob/main/term/conpty/conpty_windows.go#L155
+func (p *Pty) Start(c *exec.Cmd) error {
+	return p.start(c)
+}

pty.go

@@ -1,10 +1,11 @@
-//go:build !linux && !darwin && !freebsd && !dragonfly && !netbsd && !openbsd && !solaris
-// +build !linux,!darwin,!freebsd,!dragonfly,!netbsd,!openbsd,!solaris
+//go:build !linux && !darwin && !freebsd && !dragonfly && !netbsd && !openbsd && !solaris && !windows
+// +build !linux,!darwin,!freebsd,!dragonfly,!netbsd,!openbsd,!solaris,!windows
 
-// TODO: support Windows
 package ssh
 
 import (
+	"os/exec"
+
 	"golang.org/x/crypto/ssh"
 )
 
@@ -26,6 +27,10 @@ func (i *impl) Close() error {
 	return nil
 }
 
+func (*impl) start(*exec.Cmd) error {
+	return ErrUnsupported
+}
+
 func newPty(Context, string, Window, ssh.TerminalModes) (impl, error) {
 	return impl{}, ErrUnsupported
 }

pty_other.go

@@ -6,6 +6,8 @@ package ssh
 import (
 	"fmt"
 	"os"
+	"os/exec"
+	"syscall"
 
 	"github.com/creack/pty"
 	"github.com/u-root/u-root/pkg/termios"
@@ -57,6 +59,13 @@ func (i *impl) Resize(w int, h int) (rErr error) {
 	})
 }
 
+func (i *impl) start(c *exec.Cmd) error {
+	c.Stdin, c.Stdout, c.Stderr := i.Slave, i.Slave, i.Slave
+	if c.SysProcAttr == nil {
+		c.SysProcAttr = &syscall.SysProcAttr{}
+	}
+}
+
 func newPty(_ Context, _ string, win Window, modes ssh.TerminalModes) (_ impl, rErr error) {
 	ptm, pts, err := pty.Open()
 	if err != nil {

pty_unix.go

@@ -0,0 +1,88 @@
+//go:build windows
+// +build windows
+
+package ssh
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"syscall"
+
+	"github.com/charmbracelet/x/term/conpty"
+	"golang.org/x/crypto/ssh"
+	"golang.org/x/sys/windows"
+)
+
+type impl struct {
+	Context
+	*conpty.ConPty
+}
+
+func (i *impl) Read(p []byte) (n int, err error) {
+	return i.ConPty.Read(p)
+}
+
+func (i *impl) Write(p []byte) (n int, err error) {
+	return i.ConPty.Write(p)
+}
+
+func (i *impl) Resize(w int, h int) error {
+	return i.ConPty.Resize(w, h)
+}
+
+func (i *impl) Close() error {
+	return i.ConPty.Close()
+}
+
+func (i *impl) start(c *exec.Cmd) error {
+	pid, process, err := i.Spawn(c.Path, c.Args, &syscall.ProcAttr{
+		Dir: c.Dir,
+		Env: c.Env,
+		Sys: c.SysProcAttr,
+	})
+	if err != nil {
+		return err
+	}
+
+	c.Process, err = os.FindProcess(pid)
+	if err != nil {
+		// If we can't find the process via os.FindProcess, terminate the
+		// process as that's what we rely on for all further operations on the
+		// object.
+		if tErr := windows.TerminateProcess(process, 1); tErr != nil {
+			return fmt.Errorf("failed to terminate process after process not found: %w", tErr)
+		}
+		return fmt.Errorf("failed to find process after starting: %w", err)
+	}
+
+	type result struct {
+		*os.ProcessState
+		error
+	}
+	donec := make(chan result, 1)
+	go func() {
+		state, err := c.Process.Wait()
+		donec <- result{state, err}
+	}()
+	go func() {
+		select {
+		case <-i.Context.Done():
+			c.Err = windows.TerminateProcess(process, 1)
+		case r := <-donec:
+			c.ProcessState = r.ProcessState
+			c.Err = r.error
+		}
+	}()
+
+	return nil
+}
+
+func newPty(ctx Context, _ string, win Window, _ ssh.TerminalModes) (impl, error) {
+	c, err := conpty.New(win.Width, win.Height, 0)
+	if err != nil {
+		return impl{}, err
+	}
+
+	return impl{ctx, c}, nil
+}

pty_windows.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"log"
 	"net"
 	"sync"
 
@@ -383,14 +382,12 @@ func (sess *session) handleRequests(reqs <-chan *gossh.Request) {
 			}()
 			req.Reply(ok, nil)
 		case "window-change":
-			log.Printf("window resize event")
 			if sess.pty == nil {
 				req.Reply(false, nil)
 				continue
 			}
 			win, _, ok := parseWindow(req.Payload)
 			if ok {
-				log.Printf("window resize %dx%d", win.Width, win.Height)
 				sess.pty.Window = win
 				sess.winch <- win
 			}