*: Add --tty flag for debug / exec

This flag allows users on UNIX systems to set the tty for the program
being debugged by Delve. This is useful for debugging command line
applications which need access to their own TTY, and also for
controlling the output of the debugged programs so that IDEs may open a
dedicated terminal to show the output for the process.

.travis.yml

@@ -58,7 +58,11 @@ jobs:
 script: >-
     if [ $TRAVIS_OS_NAME = "linux" ] && [ $go_32_version ]; then
       docker pull i386/centos:7;
-      docker run -v $(pwd):/delve --privileged i386/centos:7 /bin/bash -c "set -x && \
+      docker run \
+      -v $(pwd):/delve \
+      --env TRAVIS=true \
+      --privileged i386/centos:7 \
+      /bin/bash -c "set -x && \
            cd delve && \
            yum -y update && yum -y upgrade && \
            yum -y install wget make git gcc && \

Documentation/faq.md

@@ -35,3 +35,17 @@ dlv exec --headless --continue --listen :4040 --accept-multiclient /path/to/exec
 ```
 
 Note that the connection to Delve is unauthenticated and will allow arbitrary remote code execution: *do not do this in production*.
+
+#### How can I use Delve to debug a CLI application?
+
+There are three good ways to go about this
+
+1. Run your CLI application in a separate terminal and then attach to it via `dlv attach`. 
+
+1. Run Delve in headless mode via `dlv debug --headless` and then connect to it from
+another terminal. This will place the process in the foreground and allow it to access
+the terminal TTY.
+
+1. Assign the process its own TTY. This can be done on UNIX systems via the `--tty` flag for the 
+`dlv debug` and `dlv exec` commands. For the best experience, you should create your own PTY and 
+assign it as the TTY. This can be done via [ptyme](https://github.com/derekparker/ptyme).

Documentation/usage/dlv_debug.md

@@ -21,6 +21,7 @@ dlv debug [package]
 ```
       --continue        Continue the debugged process on start.
       --output string   Output path for the binary. (default "./__debug_bin")
+      --tty string      TTY to use for the target program
 ```
 
 ### Options inherited from parent commands

Documentation/usage/dlv_exec.md

@@ -20,7 +20,8 @@ dlv exec <path/to/binary>
 ### Options
 
 ```
-      --continue   Continue the debugged process on start.
+      --continue     Continue the debugged process on start.
+      --tty string   TTY to use for the target program
 ```
 
 ### Options inherited from parent commands

cmd/dlv/cmds/commands.go

@@ -52,6 +52,8 @@ var (
 	// checkLocalConnUser is true if the debugger should check that local
 	// connections come from the same user that started the headless server
 	checkLocalConnUser bool
+	// tty is used to provide an alternate TTY for the program you wish to debug.
+	tty string
 
 	// backend selection
 	backend string
@@ -184,6 +186,7 @@ session.`,
 	}
 	debugCommand.Flags().String("output", "./__debug_bin", "Output path for the binary.")
 	debugCommand.Flags().BoolVar(&continueOnStart, "continue", false, "Continue the debugged process on start.")
+	debugCommand.Flags().StringVar(&tty, "tty", "", "TTY to use for the target program")
 	rootCommand.AddCommand(debugCommand)
 
 	// 'exec' subcommand.
@@ -207,6 +210,7 @@ or later, -gcflags="-N -l" on earlier versions of Go.`,
 			os.Exit(execute(0, args, conf, "", executingExistingFile))
 		},
 	}
+	execCommand.Flags().StringVar(&tty, "tty", "", "TTY to use for the target program")
 	execCommand.Flags().BoolVar(&continueOnStart, "continue", false, "Continue the debugged process on start.")
 	rootCommand.AddCommand(execCommand)
 
@@ -398,10 +402,11 @@ func dapCmd(cmd *cobra.Command, args []string) {
 		server := dap.NewServer(&service.Config{
 			Listener:             listener,
 			Backend:              backend,
-			Foreground:           true, // always headless
+			Foreground:           (headless && tty == ""),
 			DebugInfoDirectories: conf.DebugInfoDirectories,
 			CheckGoVersion:       checkGoVersion,
 			DisconnectChan:       disconnectChan,
+			TTY:                  tty,
 		})
 		defer server.Stop()
 
@@ -741,11 +746,12 @@ func execute(attachPid int, processArgs []string, conf *config.Config, coreFile
 			WorkingDir:           workingDir,
 			Backend:              backend,
 			CoreFile:             coreFile,
-			Foreground:           headless,
+			Foreground:           (headless && tty == ""),
 			DebugInfoDirectories: conf.DebugInfoDirectories,
 			CheckGoVersion:       checkGoVersion,
 			CheckLocalConnUser:   checkLocalConnUser,
 			DisconnectChan:       disconnectChan,
+			TTY:                  tty,
 		})
 	default:
 		fmt.Printf("Unknown API version: %d\n", apiVersion)

go.mod

@@ -5,8 +5,8 @@ go 1.11
 require (
 	github.com/cosiner/argv v0.0.0-20170225145430-13bacc38a0a5
 	github.com/cpuguy83/go-md2man v1.0.10 // indirect
+	github.com/creack/pty v1.1.9
 	github.com/google/go-dap v0.2.0
-	github.com/cpuguy83/go-md2man v1.0.8 // indirect
 	github.com/hashicorp/golang-lru v0.5.4
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/mattn/go-colorable v0.0.0-20170327083344-ded68f7a9561

go.sum

@@ -3,6 +3,8 @@ github.com/cosiner/argv v0.0.0-20170225145430-13bacc38a0a5/go.mod h1:p/NrK5tF6IC
 github.com/cpuguy83/go-md2man v1.0.8/go.mod h1:N6JayAiVKtlHSnuTCeuLSQVs75hb8q+dYQLjr7cDsKY=
 github.com/cpuguy83/go-md2man v1.0.10 h1:BSKMNlYxDvnunlTymqtgONjNnaRV1sTpcovwwjF22jk=
 github.com/cpuguy83/go-md2man v1.0.10/go.mod h1:SmD6nW6nTyfqj6ABTjUi3V3JVMnlJmwcJI5acqYI6dE=
+github.com/creack/pty v1.1.9 h1:uDmaGzcdjhF4i/plgjmEsriH11Y0o7RKapEf/LDaM3w=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV9I=

pkg/proc/gdbserial/gdbserver.go

@@ -345,7 +345,7 @@ func getLdEnvVars() []string {
 // LLDBLaunch starts an instance of lldb-server and connects to it, asking
 // it to launch the specified target program with the specified arguments
 // (cmd) on the specified directory wd.
-func LLDBLaunch(cmd []string, wd string, foreground bool, debugInfoDirs []string) (*proc.Target, error) {
+func LLDBLaunch(cmd []string, wd string, foreground bool, debugInfoDirs []string, tty string) (*proc.Target, error) {
 	if runtime.GOOS == "windows" {
 		return nil, ErrUnsupportedOS
 	}
@@ -374,6 +374,9 @@ func LLDBLaunch(cmd []string, wd string, foreground bool, debugInfoDirs []string
 		if foreground {
 			args = append(args, "--stdio-path", "/dev/tty")
 		}
+		if tty != "" {
+			args = append(args, "--stdio-path", tty)
+		}
 		if logflags.LLDBServerOutput() {
 			args = append(args, "-g", "-l", "stdout")
 		}

pkg/proc/native/nonative_darwin.go

@@ -12,12 +12,12 @@ import (
 var ErrNativeBackendDisabled = errors.New("native backend disabled during compilation")
 
 // Launch returns ErrNativeBackendDisabled.
-func Launch(cmd []string, wd string, foreground bool, _ []string) (*proc.Target, error) {
+func Launch(_ []string, _ string, _ bool, _ []string, _ string) (*proc.Target, error) {
 	return nil, ErrNativeBackendDisabled
 }
 
 // Attach returns ErrNativeBackendDisabled.
-func Attach(pid int, _ []string) (*proc.Target, error) {
+func Attach(_ int, _ []string) (*proc.Target, error) {
 	return nil, ErrNativeBackendDisabled
 }
 

pkg/proc/native/proc.go

@@ -2,6 +2,7 @@ package native
 
 import (
 	"go/ast"
+	"os"
 	"runtime"
 	"sync"
 
@@ -34,6 +35,10 @@ type nativeProcess struct {
 	childProcess        bool // this process was launched, not attached to
 	manualStopRequested bool
 
+	// Controlling terminal file descriptor for
+	// this process.
+	ctty *os.File
+
 	exited, detached bool
 }
 
@@ -343,6 +348,9 @@ func (dbp *nativeProcess) postExit() {
 	close(dbp.ptraceChan)
 	close(dbp.ptraceDoneChan)
 	dbp.bi.Close()
+	if dbp.ctty != nil {
+		dbp.ctty.Close()
+	}
 }
 
 func (dbp *nativeProcess) writeSoftwareBreakpoint(thread *nativeThread, addr uint64) error {

pkg/proc/native/proc_darwin.go

@@ -37,7 +37,7 @@ type osProcessDetails struct {
 // custom fork/exec process in order to take advantage of
 // PT_SIGEXC on Darwin which will turn Unix signals into
 // Mach exceptions.
-func Launch(cmd []string, wd string, foreground bool, _ []string) (*proc.Target, error) {
+func Launch(cmd []string, wd string, foreground bool, _ []string, _ string) (*proc.Target, error) {
 	argv0Go, err := filepath.Abs(cmd[0])
 	if err != nil {
 		return nil, err

pkg/proc/native/proc_freebsd.go

@@ -43,7 +43,7 @@ type osProcessDetails struct {
 // to be supplied to that process. `wd` is working directory of the program.
 // If the DWARF information cannot be found in the binary, Delve will look
 // for external debug files in the directories passed in.
-func Launch(cmd []string, wd string, foreground bool, debugInfoDirs []string) (*proc.Target, error) {
+func Launch(cmd []string, wd string, foreground bool, debugInfoDirs []string, tty string) (*proc.Target, error) {
 	var (
 		process *exec.Cmd
 		err     error
@@ -66,6 +66,12 @@ func Launch(cmd []string, wd string, foreground bool, debugInfoDirs []string) (*
 			signal.Ignore(syscall.SIGTTOU, syscall.SIGTTIN)
 			process.Stdin = os.Stdin
 		}
+		if tty != "" {
+			dbp.ctty, err = attachProcessToTTY(process, tty)
+			if err != nil {
+				return
+			}
+		}
 		if wd != "" {
 			process.Dir = wd
 		}

pkg/proc/native/proc_linux.go

@@ -49,7 +49,7 @@ type osProcessDetails struct {
 // to be supplied to that process. `wd` is working directory of the program.
 // If the DWARF information cannot be found in the binary, Delve will look
 // for external debug files in the directories passed in.
-func Launch(cmd []string, wd string, foreground bool, debugInfoDirs []string) (*proc.Target, error) {
+func Launch(cmd []string, wd string, foreground bool, debugInfoDirs []string, tty string) (*proc.Target, error) {
 	var (
 		process *exec.Cmd
 		err     error
@@ -67,11 +67,21 @@ func Launch(cmd []string, wd string, foreground bool, debugInfoDirs []string) (*
 		process.Args = cmd
 		process.Stdout = os.Stdout
 		process.Stderr = os.Stderr
-		process.SysProcAttr = &syscall.SysProcAttr{Ptrace: true, Setpgid: true, Foreground: foreground}
+		process.SysProcAttr = &syscall.SysProcAttr{
+			Ptrace:     true,
+			Setpgid:    true,
+			Foreground: foreground,
+		}
 		if foreground {
 			signal.Ignore(syscall.SIGTTOU, syscall.SIGTTIN)
 			process.Stdin = os.Stdin
 		}
+		if tty != "" {
+			dbp.ctty, err = attachProcessToTTY(process, tty)
+			if err != nil {
+				return
+			}
+		}
 		if wd != "" {
 			process.Dir = wd
 		}

pkg/proc/native/proc_unix.go

+// +build !windows
+
+package native
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+
+	isatty "github.com/mattn/go-isatty"
+)
+
+func attachProcessToTTY(process *exec.Cmd, tty string) (*os.File, error) {
+	f, err := os.OpenFile(tty, os.O_RDWR, 0)
+	if err != nil {
+		return nil, err
+	}
+	if !isatty.IsTerminal(f.Fd()) {
+		f.Close()
+		return nil, fmt.Errorf("%s is not a terminal", f.Name())
+	}
+	process.Stdin = f
+	process.Stdout = f
+	process.Stderr = f
+	process.SysProcAttr.Setpgid = false
+	process.SysProcAttr.Setsid = true
+	process.SysProcAttr.Setctty = true
+
+	return f, nil
+}

pkg/proc/native/proc_windows.go

@@ -20,7 +20,7 @@ type osProcessDetails struct {
 }
 
 // Launch creates and begins debugging a new process.
-func Launch(cmd []string, wd string, foreground bool, _ []string) (*proc.Target, error) {
+func Launch(cmd []string, wd string, foreground bool, _ []string, _ string) (*proc.Target, error) {
 	argv0Go, err := filepath.Abs(cmd[0])
 	if err != nil {
 		return nil, err

pkg/proc/proc_linux_test.go

@@ -14,7 +14,7 @@ func TestLoadingExternalDebugInfo(t *testing.T) {
 	fixture := protest.BuildFixture("locationsprog", 0)
 	defer os.Remove(fixture.Path)
 	stripAndCopyDebugInfo(fixture, t)
-	p, err := native.Launch(append([]string{fixture.Path}, ""), "", false, []string{filepath.Dir(fixture.Path)})
+	p, err := native.Launch(append([]string{fixture.Path}, ""), "", false, []string{filepath.Dir(fixture.Path)}, "")
 	if err != nil {
 		t.Fatal(err)
 	}

pkg/proc/proc_test.go

@@ -67,9 +67,9 @@ func withTestProcessArgs(name string, t testing.TB, wd string, args []string, bu
 
 	switch testBackend {
 	case "native":
-		p, err = native.Launch(append([]string{fixture.Path}, args...), wd, false, []string{})
+		p, err = native.Launch(append([]string{fixture.Path}, args...), wd, false, []string{}, "")
 	case "lldb":
-		p, err = gdbserial.LLDBLaunch(append([]string{fixture.Path}, args...), wd, false, []string{})
+		p, err = gdbserial.LLDBLaunch(append([]string{fixture.Path}, args...), wd, false, []string{}, "")
 	case "rr":
 		protest.MustHaveRecordingAllowed(t)
 		t.Log("recording")
@@ -2065,9 +2065,9 @@ func TestUnsupportedArch(t *testing.T) {
 
 	switch testBackend {
 	case "native":
-		p, err = native.Launch([]string{outfile}, ".", false, []string{})
+		p, err = native.Launch([]string{outfile}, ".", false, []string{}, "")
 	case "lldb":
-		p, err = gdbserial.LLDBLaunch([]string{outfile}, ".", false, []string{})
+		p, err = gdbserial.LLDBLaunch([]string{outfile}, ".", false, []string{}, "")
 	default:
 		t.Skip("test not valid for this backend")
 	}

service/config.go

@@ -50,4 +50,8 @@ type Config struct {
 
 	// DisconnectChan will be closed by the server when the client disconnects
 	DisconnectChan chan<- struct{}
+
+	// TTY is passed along to the target process on creation. Used to specify a
+	// TTY for that process.
+	TTY string
 }

service/dap/server.go

@@ -368,6 +368,7 @@ func (s *Server) onLaunchRequest(request *dap.LaunchRequest) {
 		Foreground:           s.config.Foreground,
 		DebugInfoDirectories: s.config.DebugInfoDirectories,
 		CheckGoVersion:       s.config.CheckGoVersion,
+		TTY:                  s.config.TTY,
 	}
 	var err error
 	if s.debugger, err = debugger.New(config, s.config.ProcessArgs); err != nil {

service/debugger/debugger.go

@@ -91,6 +91,10 @@ type Config struct {
 	// used to compile the executable and refuse to work on incompatible
 	// versions.
 	CheckGoVersion bool
+
+	// TTY is passed along to the target process on creation. Used to specify a
+	// TTY for that process.
+	TTY string
 }
 
 // New creates a new Debugger. ProcessArgs specify the commandline arguments for the
@@ -195,9 +199,9 @@ func (d *Debugger) Launch(processArgs []string, wd string) (*proc.Target, error)
 	}
 	switch d.config.Backend {
 	case "native":
-		return native.Launch(processArgs, wd, d.config.Foreground, d.config.DebugInfoDirectories)
+		return native.Launch(processArgs, wd, d.config.Foreground, d.config.DebugInfoDirectories, d.config.TTY)
 	case "lldb":
-		return betterGdbserialLaunchError(gdbserial.LLDBLaunch(processArgs, wd, d.config.Foreground, d.config.DebugInfoDirectories))
+		return betterGdbserialLaunchError(gdbserial.LLDBLaunch(processArgs, wd, d.config.Foreground, d.config.DebugInfoDirectories, d.config.TTY))
 	case "rr":
 		if d.target != nil {
 			// restart should not call us if the backend is 'rr'
@@ -239,9 +243,9 @@ func (d *Debugger) Launch(processArgs []string, wd string) (*proc.Target, error)
 
 	case "default":
 		if runtime.GOOS == "darwin" {
-			return betterGdbserialLaunchError(gdbserial.LLDBLaunch(processArgs, wd, d.config.Foreground, d.config.DebugInfoDirectories))
+			return betterGdbserialLaunchError(gdbserial.LLDBLaunch(processArgs, wd, d.config.Foreground, d.config.DebugInfoDirectories, d.config.TTY))
 		}
-		return native.Launch(processArgs, wd, d.config.Foreground, d.config.DebugInfoDirectories)
+		return native.Launch(processArgs, wd, d.config.Foreground, d.config.DebugInfoDirectories, d.config.TTY)
 	default:
 		return nil, fmt.Errorf("unknown backend %q", d.config.Backend)
 	}

service/debugger/debugger_unix_test.go

@@ -3,18 +3,25 @@
 package debugger
 
 import (
+	"bytes"
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"runtime"
 	"testing"
 
+	"github.com/creack/pty"
 	"github.com/go-delve/delve/pkg/gobuild"
 	protest "github.com/go-delve/delve/pkg/proc/test"
 	"github.com/go-delve/delve/service/api"
 )
 
 func TestDebugger_LaunchNoExecutablePerm(t *testing.T) {
+	defer func() {
+		os.Setenv("GOOS", runtime.GOOS)
+		os.Setenv("GOARCH", runtime.GOARCH)
+	}()
 	fixturesDir := protest.FindFixturesDir()
 	buildtestdir := filepath.Join(fixturesDir, "buildtest")
 	debugname := "debug"
@@ -29,10 +36,10 @@ func TestDebugger_LaunchNoExecutablePerm(t *testing.T) {
 	}
 	os.Setenv("GOOS", switchOS[runtime.GOOS])
 	exepath := filepath.Join(buildtestdir, debugname)
+	defer os.Remove(exepath)
 	if err := gobuild.GoBuild(debugname, []string{buildtestdir}, fmt.Sprintf("-o %s", exepath)); err != nil {
 		t.Fatalf("go build error %v", err)
 	}
-	defer os.Remove(exepath)
 	if err := os.Chmod(exepath, 0644); err != nil {
 		t.Fatal(err)
 	}
@@ -45,3 +52,46 @@ func TestDebugger_LaunchNoExecutablePerm(t *testing.T) {
 		t.Fatalf("expected error \"%s\" got \"%v\"", api.ErrNotExecutable, err)
 	}
 }
+
+func TestDebugger_LaunchWithTTY(t *testing.T) {
+	if os.Getenv("TRAVIS") == "true" {
+		if _, err := exec.LookPath("lsof"); err != nil {
+			t.Skip("skipping test in CI, system does not contain lsof")
+		}
+	}
+	// Ensure no env meddling is leftover from previous tests.
+	os.Setenv("GOOS", runtime.GOOS)
+	os.Setenv("GOARCH", runtime.GOARCH)
+
+	p, tty, err := pty.Open()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer p.Close()
+	defer tty.Close()
+
+	fixturesDir := protest.FindFixturesDir()
+	buildtestdir := filepath.Join(fixturesDir, "buildtest")
+	debugname := "debugtty"
+	exepath := filepath.Join(buildtestdir, debugname)
+	if err := gobuild.GoBuild(debugname, []string{buildtestdir}, fmt.Sprintf("-o %s", exepath)); err != nil {
+		t.Fatalf("go build error %v", err)
+	}
+	defer os.Remove(exepath)
+	var backend string
+	protest.DefaultTestBackend(&backend)
+	conf := &Config{TTY: tty.Name(), Backend: backend}
+	pArgs := []string{exepath}
+	d, err := New(conf, pArgs)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cmd := exec.Command("lsof", "-p", fmt.Sprintf("%d", d.ProcessPid()))
+	result, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Contains(result, []byte(tty.Name())) {
+		t.Fatal("process open file list does not contain expected tty")
+	}
+}

service/rpccommon/server.go

@@ -116,6 +116,7 @@ func (s *ServerImpl) Run() error {
 		Foreground:           s.config.Foreground,
 		DebugInfoDirectories: s.config.DebugInfoDirectories,
 		CheckGoVersion:       s.config.CheckGoVersion,
+		TTY:                  s.config.TTY,
 	},
 		s.config.ProcessArgs); err != nil {
 		return err

service/test/variables_test.go

@@ -131,9 +131,9 @@ func withTestProcessArgs(name string, t *testing.T, wd string, args []string, bu
 	var tracedir string
 	switch testBackend {
 	case "native":
-		p, err = native.Launch(append([]string{fixture.Path}, args...), wd, false, []string{})
+		p, err = native.Launch(append([]string{fixture.Path}, args...), wd, false, []string{}, "")
 	case "lldb":
-		p, err = gdbserial.LLDBLaunch(append([]string{fixture.Path}, args...), wd, false, []string{})
+		p, err = gdbserial.LLDBLaunch(append([]string{fixture.Path}, args...), wd, false, []string{}, "")
 	case "rr":
 		protest.MustHaveRecordingAllowed(t)
 		t.Log("recording")