cmd/dlv,terminal: fix accept-multiclient behavior

1. Check IsMulticlient and send stop request before doing anything
   else.
2. Allow init file to call 'exit'

Fixes #1430

_fixtures/exit.init

@@ -0,0 +1 @@
+exit

cmd/dlv/cmds/commands.go

@@ -500,6 +500,20 @@ func connect(addr string, clientConn net.Conn, conf *config.Config, kind execute
 	} else {
 		client = rpc2.NewClient(addr)
 	}
+	if client.IsMulticlient() {
+		state, _ := client.GetStateNonBlocking()
+		// The error return of GetState will usually be the ErrProcessExited,
+		// which we don't care about. If there are other errors they will show up
+		// later, here we are only concerned about stopping a running target so
+		// that we can initialize our connection.
+		if state != nil && state.Running {
+			_, err := client.Halt()
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "could not halt: %v", err)
+				return 1
+			}
+		}
+	}
 	if client.Recorded() && (kind == executingGeneratedFile || kind == executingGeneratedTest) {
 		// When using the rr backend remove the trace directory if we built the
 		// executable

cmd/dlv/dlv_test.go

@@ -256,3 +256,20 @@ func TestGeneratedDoc(t *testing.T) {
 		checkAutogenDoc(t, docFilename, "scripts/gen-usage-docs.go", slurpFile(t, tempDir+"/"+doc.Name()))
 	}
 }
+
+func TestExitInInit(t *testing.T) {
+	dlvbin, tmpdir := getDlvBin(t)
+	defer os.RemoveAll(tmpdir)
+
+	buildtestdir := filepath.Join(protest.FindFixturesDir(), "buildtest")
+	exitInit := filepath.Join(protest.FindFixturesDir(), "exit.init")
+	cmd := exec.Command(dlvbin, "--init", exitInit, "debug")
+	cmd.Dir = buildtestdir
+	out, err := cmd.CombinedOutput()
+	t.Logf("%q %v\n", string(out), err)
+	// dlv will exit anyway because stdin is not a tty but it will print the
+	// prompt once if the init file didn't call exit successfully.
+	if strings.Contains(string(out), "(dlv)") {
+		t.Fatal("init did not cause dlv to exit")
+	}
+}

pkg/terminal/command.go

@@ -1933,6 +1933,9 @@ func (c *Commands) executeFile(t *Term, name string) error {
 		}
 
 		if err := c.Call(line, t); err != nil {
+			if _, isExitRequest := err.(ExitRequestError); isExitRequest {
+				return err
+			}
 			fmt.Printf("%s:%d: %v\n", name, lineno, err)
 		}
 	}

pkg/terminal/terminal.go

@@ -64,20 +64,6 @@ type Term struct {
 
 // New returns a new Term.
 func New(client service.Client, conf *config.Config) *Term {
-	if client != nil && client.IsMulticlient() {
-		state, _ := client.GetStateNonBlocking()
-		// The error return of GetState will usually be the ErrProcessExited,
-		// which we don't care about. If there are other errors they will show up
-		// later, here we are only concerned about stopping a running target so
-		// that we can initialize our connection.
-		if state != nil && state.Running {
-			_, err := client.Halt()
-			if err != nil {
-				fmt.Fprintf(os.Stderr, "could not halt: %v", err)
-				return nil
-			}
-		}
-	}
 	cmds := DebugCommands(client)
 	if conf != nil && conf.Aliases != nil {
 		cmds.Merge(conf.Aliases)
@@ -204,6 +190,9 @@ func (t *Term) Run() (int, error) {
 	if t.InitFile != "" {
 		err := t.cmds.executeFile(t, t.InitFile)
 		if err != nil {
+			if _, ok := err.(ExitRequestError); ok {
+				return t.handleExit()
+			}
 			fmt.Fprintf(os.Stderr, "Error executing init file: %s\n", err)
 		}
 	}