Return thread directly from trapWait

proctl/proctl.go

@@ -279,32 +279,28 @@ func (dbp *DebuggedProcess) next() error {
 	}
 
 	for {
-		tid, err := trapWait(dbp, -1)
+		thread, err := trapWait(dbp, -1)
 		if err != nil {
 			return err
 		}
-		th, ok := dbp.Threads[tid]
-		if !ok {
-			return fmt.Errorf("unknown thread %d", tid)
-		}
-		pc, err := th.CurrentPC()
+		pc, err := thread.CurrentPC()
 		if err != nil {
 			return err
 		}
 		// Check if we've hit a software breakpoint. If so, reset PC.
-		if err = th.clearTempBreakpoint(pc - 1); err != nil {
+		if err = thread.clearTempBreakpoint(pc - 1); err != nil {
 			return err
 		}
 		// Grab the current goroutine for this thread.
-		tg, err := th.curG()
+		tg, err := thread.curG()
 		if err != nil {
 			return err
 		}
 		// Make sure we're on the same goroutine.
 		// TODO(dp) take into account goroutine exit.
 		if tg.id == curg.id {
-			if dbp.CurrentThread.Id != tid {
-				dbp.SwitchThread(tid)
+			if dbp.CurrentThread != thread {
+				dbp.SwitchThread(thread.Id)
 			}
 			break
 		}
@@ -322,20 +318,13 @@ func (dbp *DebuggedProcess) Continue() error {
 	}
 
 	fn := func() error {
-		wpid, err := trapWait(dbp, -1)
+		thread, err := trapWait(dbp, -1)
 		if err != nil {
 			return err
 		}
-
-		thread, ok := dbp.Threads[wpid]
-		if !ok {
-			return fmt.Errorf("could not find thread for %d", wpid)
+		if dbp.CurrentThread != thread {
+			dbp.SwitchThread(thread.Id)
 		}
-
-		if wpid != dbp.CurrentThread.Id {
-			dbp.SwitchThread(wpid)
-		}
-
 		pc, err := thread.CurrentPC()
 		if err != nil {
 			return err

proctl/proctl_darwin.go

@@ -171,17 +171,17 @@ func (dbp *DebuggedProcess) findExecutable() (*macho.File, error) {
 	return exe, nil
 }
 
-func trapWait(dbp *DebuggedProcess, pid int) (int, error) {
+func trapWait(dbp *DebuggedProcess, pid int) (*ThreadContext, error) {
 	port := C.mach_port_wait(dbp.os.portSet)
 
 	switch port {
 	case dbp.os.notificationPort:
 		_, status, err := wait(dbp.Pid, 0)
 		if err != nil {
-			return -1, err
+			return nil, err
 		}
 		dbp.exited = true
-		return -1, ProcessExitedError{Pid: dbp.Pid, Status: status.ExitStatus()}
+		return nil, ProcessExitedError{Pid: dbp.Pid, Status: status.ExitStatus()}
 	case C.MACH_RCV_INTERRUPTED:
 		if !dbp.halt {
 			// Call trapWait again, it seems
@@ -189,16 +189,19 @@ func trapWait(dbp *DebuggedProcess, pid int) (int, error) {
 			// process natural death _sometimes_.
 			return trapWait(dbp, pid)
 		}
-		return -1, ManualStopError{}
+		return nil, ManualStopError{}
 	case 0:
-		return -1, fmt.Errorf("error while waiting for task")
+		return nil, 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
+	thread, ok := dbp.Threads[int(port)]
+	if !ok {
+		return nil, fmt.Errorf("could not find thread for %d", port)
+	}
+	return thread, nil
 }
 
 func wait(pid, options int) (int, *sys.WaitStatus, error) {

proctl/proctl_linux.go

@@ -216,11 +216,11 @@ func stopped(pid int) bool {
 	return false
 }
 
-func trapWait(dbp *DebuggedProcess, pid int) (int, error) {
+func trapWait(dbp *DebuggedProcess, pid int) (*ThreadContext, error) {
 	for {
 		wpid, status, err := wait(pid, 0)
 		if err != nil {
-			return -1, fmt.Errorf("wait err %s %d", err, pid)
+			return nil, fmt.Errorf("wait err %s %d", err, pid)
 		}
 		if wpid == 0 {
 			continue
@@ -231,37 +231,41 @@ func trapWait(dbp *DebuggedProcess, pid int) (int, error) {
 
 		if status.Exited() && wpid == dbp.Pid {
 			dbp.exited = true
-			return -1, ProcessExitedError{Pid: wpid, Status: status.ExitStatus()}
+			return nil, ProcessExitedError{Pid: wpid, Status: status.ExitStatus()}
 		}
 		if status.StopSignal() == sys.SIGTRAP && status.TrapCause() == sys.PTRACE_EVENT_CLONE {
 			// A traced thread has cloned a new thread, grab the pid and
 			// add it to our list of traced threads.
 			cloned, err := sys.PtraceGetEventMsg(wpid)
 			if err != nil {
-				return -1, fmt.Errorf("could not get event message: %s", err)
+				return nil, fmt.Errorf("could not get event message: %s", err)
 			}
 
 			th, err := dbp.addThread(int(cloned), false)
 			if err != nil {
-				return -1, err
+				return nil, err
 			}
 
 			err = th.Continue()
 			if err != nil {
-				return -1, fmt.Errorf("could not continue new thread %d %s", cloned, err)
+				return nil, fmt.Errorf("could not continue new thread %d %s", cloned, err)
 			}
 
 			err = dbp.Threads[int(wpid)].Continue()
 			if err != nil {
-				return -1, fmt.Errorf("could not continue new thread %d %s", cloned, err)
+				return nil, fmt.Errorf("could not continue new thread %d %s", cloned, err)
 			}
 			continue
 		}
 		if status.StopSignal() == sys.SIGTRAP {
-			return wpid, nil
+			thread, ok := dbp.Threads[wpid]
+			if !ok {
+				return nil, fmt.Errorf("could not find thread for %d", wpid)
+			}
+			return thread, nil
 		}
 		if status.StopSignal() == sys.SIGSTOP && dbp.halt {
-			return -1, ManualStopError{}
+			return nil, ManualStopError{}
 		}
 	}
 }