revert stringstack.go changes

common/stringstack/stringstack.go

@@ -6,7 +6,8 @@ import (
 
 // StringStack is a basic LIFO "stack" for storing strings.
 type StringStack struct {
-	stack []string
+	Locked bool
+	stack  []string
 }
 
 // New creates a new instance of StringStack
@@ -19,6 +20,20 @@ func (s *StringStack) Set(v string) {
 	s.stack = []string{v}
 }
 
+// Lock freezes the StringStack
+func (s *StringStack) Lock() {
+	if !s.Locked {
+		s.Locked = true
+	}
+}
+
+// Unlock unfreezes the StringStack
+func (s *StringStack) Unlock() {
+	if s.Locked {
+		s.Locked = false
+	}
+}
+
 // Push pushes a string onto the stack.
 func (s *StringStack) Push(v string) {
 	s.stack = append(s.stack, v)
@@ -26,11 +41,12 @@ func (s *StringStack) Push(v string) {
 
 // Pop pops a string from the stack.
 func (s *StringStack) Pop() (string, error) {
+	var x string
 	if len(s.stack) == 0 {
-		return "", errors.New("no items on stack")
+		return x, errors.New("no items on stack")
 	}
 
-	x := s.stack[len(s.stack)-1]
+	x = s.stack[len(s.stack)-1]
 	s.stack = s.stack[:len(s.stack)-1]
 
 	return x, nil

server/channelserver/handlers_stage.go

@@ -157,6 +157,7 @@ func handleMsgSysEnterStage(s *Session, p mhfpacket.MHFPacket) {
 		s.stage.reservedClientSlots[s.charID] = false
 		s.stage.Unlock()
 		s.stageMoveStack.Push(s.stage.id)
+		s.stageMoveStack.Lock()
 	}
 
 	if s.reservationStage != nil {
@@ -170,6 +171,7 @@ func handleMsgSysBackStage(s *Session, p mhfpacket.MHFPacket) {
 	pkt := p.(*mhfpacket.MsgSysBackStage)
 
 	// Transfer back to the saved stage ID before the previous move or enter.
+	s.stageMoveStack.Unlock()
 	backStage, err := s.stageMoveStack.Pop()
 	if backStage == "" || err != nil {
 		backStage = "sl1Ns200p0a0u0"
@@ -190,7 +192,9 @@ func handleMsgSysMoveStage(s *Session, p mhfpacket.MHFPacket) {
 	pkt := p.(*mhfpacket.MsgSysMoveStage)
 
 	// Set a new move stack from the given stage ID
-	s.stageMoveStack.Set(pkt.StageID)
+	if !s.stageMoveStack.Locked {
+		s.stageMoveStack.Set(pkt.StageID)
+	}
 
 	doStageTransfer(s, pkt.AckHandle, pkt.StageID)
 }