feature: Added raw terminal support in monitor command (#2291)

* Removed useless tty abstraction

* Print 'Connected to...' message immediatly after connection

* Added terminal raw mode

* Make local the argument/flags of 'monitor' command

* Applied code suggestion

Author: cmaglie

Diff for: internal/cli/feedback/terminal.go

@@ -41,6 +41,28 @@ func InteractiveStreams() (io.Reader, io.Writer, error) {
 	return os.Stdin, stdOut, nil
 }
 
+var oldStateStdin *term.State
+
+// SetRawModeStdin sets the stdin stream in RAW mode (no buffering, echo disabled,
+// no terminal escape codes nor signals interpreted)
+func SetRawModeStdin() {
+	if oldStateStdin != nil {
+		panic("terminal already in RAW mode")
+	}
+	oldStateStdin, _ = term.MakeRaw(int(os.Stdin.Fd()))
+}
+
+// RestoreModeStdin restore the terminal settings to the normal non-RAW state. This
+// function must be called after SetRawModeStdin to not leave the terminal in an
+// undefined state.
+func RestoreModeStdin() {
+	if oldStateStdin == nil {
+		return
+	}
+	_ = term.Restore(int(os.Stdin.Fd()), oldStateStdin)
+	oldStateStdin = nil
+}
+
 func isTerminal() bool {
 	return term.IsTerminal(int(os.Stdin.Fd()))
 }

Diff for: internal/cli/monitor/monitor.go

@@ -16,6 +16,7 @@
 package monitor
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -35,29 +36,34 @@ import (
 	"github.com/fatih/color"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"go.bug.st/cleanup"
 )
 
-var (
-	portArgs arguments.Port
-	describe bool
-	configs  []string
-	quiet    bool
-	fqbn     arguments.Fqbn
-	tr       = i18n.Tr
-)
+var tr = i18n.Tr
 
 // NewCommand created a new `monitor` command
 func NewCommand() *cobra.Command {
+	var (
+		raw      bool
+		portArgs arguments.Port
+		describe bool
+		configs  []string
+		quiet    bool
+		fqbn     arguments.Fqbn
+	)
 	monitorCommand := &cobra.Command{
 		Use:   "monitor",
 		Short: tr("Open a communication port with a board."),
 		Long:  tr("Open a communication port with a board."),
 		Example: "" +
 			"  " + os.Args[0] + " monitor -p /dev/ttyACM0\n" +
 			"  " + os.Args[0] + " monitor -p /dev/ttyACM0 --describe",
-		Run: runMonitorCmd,
+		Run: func(cmd *cobra.Command, args []string) {
+			runMonitorCmd(&portArgs, &fqbn, configs, describe, quiet, raw)
+		},
 	}
 	portArgs.AddToCommand(monitorCommand)
+	monitorCommand.Flags().BoolVar(&raw, "raw", false, tr("Set terminal in raw mode (unbuffered)."))
 	monitorCommand.Flags().BoolVar(&describe, "describe", false, tr("Show all the settings of the communication port."))
 	monitorCommand.Flags().StringSliceVarP(&configs, "config", "c", []string{}, tr("Configure communication port settings. The format is <ID>=<value>[,<ID>=<value>]..."))
 	monitorCommand.Flags().BoolVarP(&quiet, "quiet", "q", false, tr("Run in silent mode, show only monitor input and output."))
@@ -66,7 +72,7 @@ func NewCommand() *cobra.Command {
 	return monitorCommand
 }
 
-func runMonitorCmd(cmd *cobra.Command, args []string) {
+func runMonitorCmd(portArgs *arguments.Port, fqbn *arguments.Fqbn, configs []string, describe, quiet, raw bool) {
 	instance := instance.CreateAndInit()
 	logrus.Info("Executing `arduino-cli monitor`")
 
@@ -93,12 +99,6 @@ func runMonitorCmd(cmd *cobra.Command, args []string) {
 		return
 	}
 
-	tty, err := newStdInOutTerminal()
-	if err != nil {
-		feedback.FatalError(err, feedback.ErrGeneric)
-	}
-	defer tty.Close()
-
 	configuration := &rpc.MonitorPortConfiguration{}
 	if len(configs) > 0 {
 		for _, config := range configs {
@@ -151,9 +151,33 @@ func runMonitorCmd(cmd *cobra.Command, args []string) {
 	}
 	defer portProxy.Close()
 
-	ctx, cancel := context.WithCancel(context.Background())
+	if !quiet {
+		feedback.Print(tr("Connected to %s! Press CTRL-C to exit.", portAddress))
+	}
+
+	ttyIn, ttyOut, err := feedback.InteractiveStreams()
+	if err != nil {
+		feedback.FatalError(err, feedback.ErrGeneric)
+	}
+
+	ctx, cancel := cleanup.InterruptableContext(context.Background())
+	if raw {
+		feedback.SetRawModeStdin()
+		defer func() {
+			feedback.RestoreModeStdin()
+		}()
+
+		// In RAW mode CTRL-C is not converted into an Interrupt by
+		// the terminal, we must intercept ASCII 3 (CTRL-C) on our own...
+		ctrlCDetector := &charDetectorWriter{
+			callback:     cancel,
+			detectedChar: 3, // CTRL-C
+		}
+		ttyIn = io.TeeReader(ttyIn, ctrlCDetector)
+	}
+
 	go func() {
-		_, err := io.Copy(tty, portProxy)
+		_, err := io.Copy(ttyOut, portProxy)
 		if err != nil && !errors.Is(err, io.EOF) {
 			if !quiet {
 				feedback.Print(tr("Port closed: %v", err))
@@ -162,7 +186,7 @@ func runMonitorCmd(cmd *cobra.Command, args []string) {
 		cancel()
 	}()
 	go func() {
-		_, err := io.Copy(portProxy, tty)
+		_, err := io.Copy(portProxy, ttyIn)
 		if err != nil && !errors.Is(err, io.EOF) {
 			if !quiet {
 				feedback.Print(tr("Port closed: %v", err))
@@ -171,14 +195,22 @@ func runMonitorCmd(cmd *cobra.Command, args []string) {
 		cancel()
 	}()
 
-	if !quiet {
-		feedback.Print(tr("Connected to %s! Press CTRL-C to exit.", portAddress))
-	}
-
 	// Wait for port closed
 	<-ctx.Done()
 }
 
+type charDetectorWriter struct {
+	callback     func()
+	detectedChar byte
+}
+
+func (cd *charDetectorWriter) Write(buf []byte) (int, error) {
+	if bytes.IndexByte(buf, cd.detectedChar) != -1 {
+		cd.callback()
+	}
+	return len(buf), nil
+}
+
 type detailsResult struct {
 	Settings []*rpc.MonitorPortSettingDescriptor `json:"settings"`
 }