Ensure thread is stopped before setting breakpoint

For hardware breakpoints we have to set them on every thread. It could
be the case that another thread is running. Stop it first, set the
breakpoint, then continue it.

proc/breakpoints.go

@@ -90,8 +90,15 @@ func (dbp *Process) setBreakpoint(tid int, addr uint64, temp bool) (*Breakpoint,
 		if used {
 			continue
 		}
-		for t, _ := range dbp.Threads {
+		for tid, t := range dbp.Threads {
-			if err := dbp.setHardwareBreakpoint(i, t, addr); err != nil {
+			if t.running {
+				err := t.Halt()
+				if err != nil {
+					return nil, err
+				}
+				defer t.Continue()
+			}
+			if err := dbp.setHardwareBreakpoint(i, tid, addr); err != nil {
 				return nil, fmt.Errorf("could not set hardware breakpoint on thread %d: %s", t, err)
 			}
 		}

proc/proc_linux.go

@@ -271,12 +271,15 @@ func (dbp *Process) trapWait(pid int) (*Thread, error) {
 			continue
 		}
 		if status.StopSignal() == sys.SIGTRAP {
+			th.running = false
 			return dbp.handleBreakpointOnThread(wpid)
 		}
 		if status.StopSignal() == sys.SIGTRAP && dbp.halt {
+			th.running = false
 			return th, nil
 		}
 		if status.StopSignal() == sys.SIGSTOP && dbp.halt {
+			th.running = false
 			return nil, ManualStopError{}
 		}
 		if th != nil {

proc/threads.go

@@ -65,7 +65,11 @@ func (thread *Thread) Continue() error {
 // Otherwise we simply execute the next instruction.
 func (thread *Thread) Step() (err error) {
 	thread.singleStepping = true
-	defer func() { thread.singleStepping = false }()
+	thread.running = true
+	defer func() {
+		thread.singleStepping = false
+		thread.running = false
+	}()
 	pc, err := thread.PC()
 	if err != nil {
 		return err

proc/threads_darwin.go

@@ -18,6 +18,7 @@ func (t *Thread) Halt() error {
 	if kret != C.KERN_SUCCESS {
 		return fmt.Errorf("could not suspend thread %d", t.Id)
 	}
+	t.running = false
 	return nil
 }
 
@@ -35,6 +36,7 @@ func (t *Thread) singleStep() error {
 }
 
 func (t *Thread) resume() error {
+	t.running = true
 	// TODO(dp) set flag for ptrace stops
 	var err error
 	t.dbp.execPtraceFunc(func() { err = PtraceCont(t.dbp.Pid, 0) })

proc/threads_linux.go

@@ -18,16 +18,18 @@ func (t *Thread) Halt() error {
 	}
 	err := sys.Tgkill(t.dbp.Pid, t.Id, sys.SIGSTOP)
 	if err != nil {
-		return fmt.Errorf("Halt err %s %d", err, t.Id)
+		return fmt.Errorf("halt err %s on thread %d", err, t.Id)
 	}
 	_, _, err = wait(t.Id, 0)
 	if err != nil {
-		return fmt.Errorf("wait err %s %d", err, t.Id)
+		return fmt.Errorf("wait err %s on thread %d", err, t.Id)
 	}
+	t.running = false
 	return nil
 }
 
 func (t *Thread) resume() (err error) {
+	t.running = true
 	t.dbp.execPtraceFunc(func() { err = PtraceCont(t.Id, 0) })
 	return
 }