refactor: decouple gotty app with terminal backends

backends/ptycommand/command.go

@@ -0,0 +1,130 @@
+package ptycommand
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"net/url"
+	"os"
+	"os/exec"
+	"syscall"
+	"text/template"
+	"unsafe"
+
+	"github.com/yudai/gotty/backends"
+
+	"github.com/kr/pty"
+)
+
+type Options struct {
+	CloseSignal int    `hcl:"close_signal" flagName:"close-signal" flagSName:"" flagDescribe:"Signal sent to the command process when gotty close it (default: SIGHUP)" default:"1"`
+	TitleFormat string `hcl:"title_format" flagName:"title-format" flagSName:"" flagDescribe:"Title format of browser window" default:"GoTTY - {{ .Command }} ({{ .Hostname }})"`
+}
+
+type CommandClientContextManager struct {
+	command []string
+
+	options       *Options
+	titleTemplate *template.Template
+}
+
+func NewCommandClientContextManager(command []string, options *Options) (*CommandClientContextManager, error) {
+	titleTemplate, err := template.New("title").Parse(options.TitleFormat)
+	if err != nil {
+		return nil, fmt.Errorf("Title format string syntax error: %v", options.TitleFormat)
+	}
+	return &CommandClientContextManager{command: command, options: options, titleTemplate: titleTemplate}, nil
+}
+
+type CommandClientContext struct {
+	cmd *exec.Cmd
+	pty *os.File
+	mgr *CommandClientContextManager
+}
+
+func (mgr *CommandClientContextManager) New(params url.Values) (backends.ClientContext, error) {
+	argv := mgr.command[1:]
+	args := params["arg"]
+	if len(args) != 0 {
+		argv = append(argv, args...)
+	}
+
+	cmd := exec.Command(mgr.command[0], argv...)
+	return &CommandClientContext{cmd: cmd, mgr: mgr}, nil
+}
+
+func (context *CommandClientContext) WindowTitle() (title string, err error) {
+	hostname, _ := os.Hostname()
+
+	titleVars := struct {
+		Command  string
+		Pid      int
+		Hostname string
+	}{
+		Command:  context.cmd.Path,
+		Pid:      context.cmd.Process.Pid,
+		Hostname: hostname,
+	}
+
+	titleBuffer := new(bytes.Buffer)
+	if err := context.mgr.titleTemplate.Execute(titleBuffer, titleVars); err != nil {
+		return "", err
+	}
+	return titleBuffer.String(), nil
+}
+
+func (context *CommandClientContext) Start(exitCh chan bool) {
+	ptyIo, err := pty.Start(context.cmd)
+	if err != nil {
+		log.Printf("failed to start command %v", err)
+		exitCh <- true
+	} else {
+		context.pty = ptyIo
+	}
+}
+
+func (context *CommandClientContext) InputWriter() io.Writer {
+	return context.pty
+}
+
+func (context *CommandClientContext) OutputReader() io.Reader {
+	return context.pty
+}
+
+func (context *CommandClientContext) ResizeTerminal(width, height uint16) error {
+	window := struct {
+		row uint16
+		col uint16
+		x   uint16
+		y   uint16
+	}{
+		height,
+		width,
+		0,
+		0,
+	}
+	_, _, errno := syscall.Syscall(
+		syscall.SYS_IOCTL,
+		context.pty.Fd(),
+		syscall.TIOCSWINSZ,
+		uintptr(unsafe.Pointer(&window)),
+	)
+	if errno != 0 {
+		return errno
+	} else {
+		return nil
+	}
+}
+
+func (context *CommandClientContext) TearDown() error {
+	context.pty.Close()
+
+	// Even if the PTY has been closed,
+	// Read(0 in processSend() keeps blocking and the process doen't exit
+	if context.cmd != nil && context.cmd.Process != nil {
+		context.cmd.Process.Signal(syscall.Signal(context.mgr.options.CloseSignal))
+		context.cmd.Wait()
+	}
+	return nil
+}