Paper/patches/server/0279-force-entity-dismount-during-teleportation.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Thu, 15 Nov 2018 13:38:37 +0000
Subject: [PATCH] force entity dismount during teleportation

Entities must be dismounted before teleportation in order to avoid
multiple issues in the server with regards to teleportation, shamefully,
too many plugins rely on the events firing, which means that not firing
these events caues more issues than it solves;

In order to counteract this, Entity dismount/exit vehicle events have
been modified to supress cancellation (and has a method to allow plugins
to check if this has been set), noting that cancellation will be silently
surpressed given that plugins are not expecting this event to not be cancellable.

This is a far from ideal scenario, however: given the current state of this
event and other alternatives causing issues elsewhere, I believe that
this is going to be the best soultion all around.

Improvements/suggestions welcome!

diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 6d04954493680bc4fbad67ff2e43411f970f78f5..1793fbd803bfdb5d43d83d15b238d70da06b8780 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2606,11 +2606,16 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
     }
 
     public void removeVehicle() {
+        // Paper start - Force entity dismount during teleportation
+        stopRiding(false);
+    }
+    public void stopRiding(boolean suppressCancellation) {
+        // Paper end - Force entity dismount during teleportation
         if (this.vehicle != null) {
             Entity entity = this.vehicle;
 
             this.vehicle = null;
-            if (!entity.removePassenger(this)) this.vehicle = entity; // CraftBukkit
+            if (!entity.removePassenger(this, suppressCancellation)) this.vehicle = entity; // CraftBukkit // Paper - Force entity dismount during teleportation
         }
 
     }
@@ -2641,7 +2646,10 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
         }
     }
 
-    protected boolean removePassenger(Entity entity) { // CraftBukkit
+    // Paper start - Force entity dismount during teleportation
+    protected boolean removePassenger(Entity entity) { return removePassenger(entity, false);}
+    protected boolean removePassenger(Entity entity, boolean suppressCancellation) { // CraftBukkit
+        // Paper end - Force entity dismount during teleportation
         if (entity.getVehicle() == this) {
             throw new IllegalStateException("Use x.stopRiding(y), not y.removePassenger(x)");
         } else {
@@ -2651,7 +2659,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
             if (this.getBukkitEntity() instanceof Vehicle && entity.getBukkitEntity() instanceof LivingEntity) {
                 VehicleExitEvent event = new VehicleExitEvent(
                         (Vehicle) this.getBukkitEntity(),
-                        (LivingEntity) entity.getBukkitEntity()
+                        (LivingEntity) entity.getBukkitEntity(), !suppressCancellation // Paper - Force entity dismount during teleportation
                 );
                 // Suppress during worldgen
                 if (this.valid) {
@@ -2664,7 +2672,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
                 }
             }
 
-            EntityDismountEvent event = new EntityDismountEvent(entity.getBukkitEntity(), this.getBukkitEntity());
+            EntityDismountEvent event = new EntityDismountEvent(entity.getBukkitEntity(), this.getBukkitEntity(), !suppressCancellation); // Paper - Force entity dismount during teleportation
             // Suppress during worldgen
             if (this.valid) {
                 Bukkit.getPluginManager().callEvent(event);
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index 0085d4727e9bd1c6f451666e6012b8abcd74d129..9e3571220ba3eef5fa950ddd83af13ff45ae38ae 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3471,9 +3471,15 @@ public abstract class LivingEntity extends Entity implements Attackable {
 
     @Override
     public void stopRiding() {
+        // Paper start - Force entity dismount during teleportation
+        stopRiding(false);
+    }
+    @Override
+    public void stopRiding(boolean suppressCancellation) {
+        // Paper end - Force entity dismount during teleportation
         Entity entity = this.getVehicle();
 
-        super.stopRiding();
+        super.stopRiding(suppressCancellation); // Paper - Force entity dismount during teleportation
         if (entity != null && entity != this.getVehicle() && !this.level().isClientSide) {
             this.dismountVehicle(entity);
         }
diff --git a/src/main/java/net/minecraft/world/entity/player/Player.java b/src/main/java/net/minecraft/world/entity/player/Player.java
index 0d8261e15a1a66df17727788c387dca8fbe2ae84..76a3e38a49d6ea8cf01604be4da12ad4e4fa3da4 100644
--- a/src/main/java/net/minecraft/world/entity/player/Player.java
+++ b/src/main/java/net/minecraft/world/entity/player/Player.java
@@ -1149,7 +1149,13 @@ public abstract class Player extends LivingEntity {
 
     @Override
     public void removeVehicle() {
-        super.removeVehicle();
+        // Paper start - Force entity dismount during teleportation
+        stopRiding(false);
+    }
+    @Override
+    public void stopRiding(boolean suppressCancellation) {
+        super.stopRiding(suppressCancellation);
+        // Paper end - Force entity dismount during teleportation
         this.boardingCooldown = 0;
     }