Return error when invoking Delve with invalid path

Fixes #154

cmd/dlv/main.go

@@ -61,6 +61,13 @@ func main() {
 		os.Exit(0)
 	}
 
+	defer func() {
+		if err := recover(); err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+	}()
+
 	status := run(addr, logEnabled, headless)
 	fmt.Println("[Hope I was of service hunting your bug!]")
 	os.Exit(status)
@@ -121,6 +128,7 @@ func run(addr string, logEnabled, headless bool) int {
 		fmt.Printf("couldn't start listener: %s\n", err)
 		return 1
 	}
+	defer listener.Close()
 
 	// Create and start a debugger server
 	var server service.Server
@@ -129,7 +137,10 @@ func run(addr string, logEnabled, headless bool) int {
 		ProcessArgs: processArgs,
 		AttachPid:   attachPid,
 	}, logEnabled)
-	go server.Run()
+	if err := server.Run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		return 1
+	}
 
 	var status int
 	if !headless {

proc/proc_darwin.go

@@ -9,6 +9,7 @@ import (
 	"debug/macho"
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"sync"
 	"unsafe"
@@ -38,8 +39,18 @@ func Launch(cmd []string) (*Process, error) {
 	if err != nil {
 		return nil, err
 	}
+	if filepath.Base(cmd[0]) == cmd[0] {
+		if _, err := exec.LookPath(cmd[0]); err != nil {
+			return nil, err
+		}
+	}
 	argv0 := C.CString(argv0Go)
 
+	// Make sure the binary exists.
+	if _, err := os.Stat(argv0Go); err != nil {
+		return nil, err
+	}
+
 	argvSlice := make([]*C.char, 0, len(cmd))
 	for _, arg := range cmd {
 		argvSlice = append(argvSlice, C.CString(arg))

service/debugger/debugger.go

@@ -46,14 +46,14 @@ func New(config *Config) (*Debugger, error) {
 		log.Printf("attaching to pid %d", d.config.AttachPid)
 		p, err := proc.Attach(d.config.AttachPid)
 		if err != nil {
-			return nil, fmt.Errorf("couldn't attach to pid %d: %s", d.config.AttachPid, err)
+			return nil, fmt.Errorf("could not attach to pid %d: %s", d.config.AttachPid, err)
 		}
 		d.process = p
 	} else {
 		log.Printf("launching process with args: %v", d.config.ProcessArgs)
 		p, err := proc.Launch(d.config.ProcessArgs)
 		if err != nil {
-			return nil, fmt.Errorf("couldn't launch process: %s", err)
+			return nil, fmt.Errorf("could not launch process: %s", err)
 		}
 		d.process = p
 	}

service/rpc/server.go

@@ -45,11 +45,7 @@ func (s *RPCServer) Stop(kill bool) error {
 // itself can be stopped with the `detach` API. Run blocks until the HTTP
 // server stops.
 func (s *RPCServer) Run() error {
-	c, err := s.listener.Accept()
-	if err != nil {
-		return err
-	}
-
+	var err error
 	// Create and start the debugger
 	if s.debugger, err = debugger.New(&debugger.Config{
 		ProcessArgs: s.config.ProcessArgs,
@@ -58,9 +54,16 @@ func (s *RPCServer) Run() error {
 		return err
 	}
 
+	go func() {
+		c, err := s.listener.Accept()
+		if err != nil {
+			panic(err)
+		}
+
 		rpcs := grpc.NewServer()
 		rpcs.Register(s)
 		rpcs.ServeCodec(jsonrpc.NewServerCodec(c))
+	}()
 	return nil
 }
 

service/test/integration_test.go

@@ -33,7 +33,9 @@ func withTestClient(name string, t *testing.T, fn func(c service.Client)) {
 		Listener:    listener,
 		ProcessArgs: []string{protest.BuildFixture(name).Path},
 	}, false)
-	go server.Run()
+	if err := server.Run(); err != nil {
+		t.Fatal(err)
+	}
 	client := rpc.NewClient(listener.Addr().String())
 	defer func() {
 		client.Detach(true)
@@ -42,6 +44,21 @@ func withTestClient(name string, t *testing.T, fn func(c service.Client)) {
 	fn(client)
 }
 
+func TestRunWithInvalidPath(t *testing.T) {
+	listener, err := net.Listen("tcp", "localhost:0")
+	if err != nil {
+		t.Fatalf("couldn't start listener: %s\n", err)
+	}
+	defer listener.Close()
+	server := rpc.NewServer(&service.Config{
+		Listener:    listener,
+		ProcessArgs: []string{"invalid_path"},
+	}, false)
+	if err := server.Run(); err == nil {
+		t.Fatal("Expected Run to return error for invalid program path")
+	}
+}
+
 func TestClientServer_exit(t *testing.T) {
 	withTestClient("continuetestprog", t, func(c service.Client) {
 		state, err := c.GetState()