Improve handling of process natural death (OS X)

client/cli/cli.go

@@ -105,11 +105,15 @@ func Run(args []string) {
 		}
 
 		cmdstr, args := parseCommand(cmdstr)
-
 		if cmdstr == "exit" {
 			handleExit(dbp, t, 0)
 		}
 
+		if dbp.Exited() && cmdstr != "help" {
+			fmt.Fprintf(os.Stderr, "Process has already exited.\n")
+			continue
+		}
+
 		cmd := cmds.Find(cmdstr)
 		if err := cmd(dbp, args...); err != nil {
 			switch err.(type) {
@@ -132,39 +136,41 @@ func handleExit(dbp *proctl.DebuggedProcess, t *Term, status int) {
 		f.Close()
 	}
 
-	answer, err := t.line.Prompt("Would you like to kill the process? [y/n]")
-	if err != nil {
-		t.die(2, io.EOF)
-	}
-	answer = strings.TrimSuffix(answer, "\n")
-
-	for _, bp := range dbp.HWBreakPoints {
-		if bp == nil {
-			continue
+	if !dbp.Exited() {
+		for _, bp := range dbp.HWBreakPoints {
+			if bp == nil {
+				continue
+			}
+			if _, err := dbp.Clear(bp.Addr); err != nil {
+				fmt.Printf("Can't clear breakpoint @%x: %s\n", bp.Addr, err)
+			}
 		}
-		if _, err := dbp.Clear(bp.Addr); err != nil {
-			fmt.Printf("Can't clear breakpoint @%x: %s\n", bp.Addr, err)
+
+		for pc := range dbp.BreakPoints {
+			if _, err := dbp.Clear(pc); err != nil {
+				fmt.Printf("Can't clear breakpoint @%x: %s\n", pc, err)
+			}
 		}
-	}
 
-	for pc := range dbp.BreakPoints {
-		if _, err := dbp.Clear(pc); err != nil {
-			fmt.Printf("Can't clear breakpoint @%x: %s\n", pc, err)
+		answer, err := t.line.Prompt("Would you like to kill the process? [y/n]")
+		if err != nil {
+			t.die(2, io.EOF)
 		}
-	}
+		answer = strings.TrimSuffix(answer, "\n")
 
-	fmt.Println("Detaching from process...")
-	err = sys.PtraceDetach(dbp.Process.Pid)
-	if err != nil {
-		t.die(2, "Could not detach", err)
-	}
+		fmt.Println("Detaching from process...")
+		err = sys.PtraceDetach(dbp.Process.Pid)
+		if err != nil {
+			t.die(2, "Could not detach", err)
+		}
 
-	if answer == "y" {
-		fmt.Println("Killing process", dbp.Process.Pid)
+		if answer == "y" {
+			fmt.Println("Killing process", dbp.Process.Pid)
 
-		err := dbp.Process.Kill()
-		if err != nil {
-			fmt.Println("Could not kill process", err)
+			err := dbp.Process.Kill()
+			if err != nil {
+				fmt.Println("Could not kill process", err)
+			}
 		}
 	}
 

proctl/proctl.go

@@ -35,6 +35,7 @@ type DebuggedProcess struct {
 	breakpointIDCounter int
 	running             bool
 	halt                bool
+	exited              bool
 }
 
 // A ManualStopError happens when the user triggers a
@@ -87,6 +88,12 @@ func Launch(cmd []string) (*DebuggedProcess, error) {
 	return newDebugProcess(proc.Process.Pid, false)
 }
 
+// Returns whether or not Delve thinks the debugged
+// process has exited.
+func (dbp *DebuggedProcess) Exited() bool {
+	return dbp.exited
+}
+
 // Returns whether or not Delve thinks the debugged
 // process is currently executing.
 func (dbp *DebuggedProcess) Running() bool {
@@ -242,6 +249,7 @@ func (dbp *DebuggedProcess) Continue() error {
 		if err != nil {
 			return err
 		}
+
 		thread, ok := dbp.Threads[wpid]
 		if !ok {
 			return fmt.Errorf("could not find thread for %d", wpid)
@@ -380,6 +388,9 @@ func newDebugProcess(pid int, attach bool) (*DebuggedProcess, error) {
 }
 
 func (dbp *DebuggedProcess) run(fn func() error) error {
+	if dbp.exited {
+		return fmt.Errorf("process has already exited")
+	}
 	dbp.running = true
 	dbp.halt = false
 	defer func() { dbp.running = false }()

proctl/proctl_darwin.c

@@ -122,14 +122,14 @@ mach_port_wait(mach_port_t port_set) {
 	// Wait for mach msg.
 	kret = mach_msg(&msg.hdr, MACH_RCV_MSG|MACH_RCV_INTERRUPT,
 			0, sizeof(msg.data), port_set, 0, MACH_PORT_NULL);
-
-	if (kret == MACH_RCV_INTERRUPTED || kret != MACH_MSG_SUCCESS) return 0;
+	if (kret == MACH_RCV_INTERRUPTED) return kret;
+	if (kret != MACH_MSG_SUCCESS) return 0;
 
 	mach_msg_body_t *bod = (mach_msg_body_t*)(&msg.hdr + 1);
 	mach_msg_port_descriptor_t *desc = (mach_msg_port_descriptor_t *)(bod + 1);
 	thread = desc[0].name;
 
-	// Exception
+
 	switch (msg.hdr.msgh_id) {
 		case 2401: // Exception
 			kret = thread_suspend(thread);

proctl/proctl_darwin.go

@@ -177,20 +177,31 @@ func (dbp *DebuggedProcess) findExecutable() (*macho.File, error) {
 
 func trapWait(dbp *DebuggedProcess, pid int) (int, error) {
 	port := C.mach_port_wait(dbp.os.portSet)
+
 	switch port {
-	case C.MACH_RCV_INTERRUPTED:
-		return -1, ManualStopError{}
 	case dbp.os.notificationPort:
 		_, status, err := wait(dbp.Pid, 0)
 		if err != nil {
 			return -1, err
 		}
+		dbp.exited = true
 		return -1, ProcessExitedError{Pid: dbp.Pid, Status: status.ExitStatus()}
+	case C.MACH_RCV_INTERRUPTED:
+		if !dbp.halt {
+			// Call trapWait again, it seems
+			// MACH_RCV_INTERRUPTED is emitted before
+			// process natural death _sometimes_.
+			return trapWait(dbp, pid)
+		}
+		return -1, ManualStopError{}
 	case 0:
 		return -1, fmt.Errorf("error while waiting for task")
 	}
 
+	// Since we cannot be notified of new threads on OS X
+	// this is as good a time as any to check for them.
 	dbp.updateThreadList()
+
 	return int(port), nil
 }