From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 11 Jul 2020 03:54:28 -0400
Subject: [PATCH] Thread Safe Vanilla Command permission checking

Datapacks check this on load and are built concurrently. This was breaking them badly due
to race conditions.

Plus, .canUse we want to be safe for async anyways.

diff --git a/src/main/java/com/mojang/brigadier/tree/CommandNode.java b/src/main/java/com/mojang/brigadier/tree/CommandNode.java
index 3384501f83d445f45aa8233e98c7597daa67b8ef..bd12d372a04172504b3664a8136e534ca1b1712d 100644
--- a/src/main/java/com/mojang/brigadier/tree/CommandNode.java
+++ b/src/main/java/com/mojang/brigadier/tree/CommandNode.java
@@ -75,10 +75,10 @@ public abstract class CommandNode<S> implements Comparable<CommandNode<S>> {
     public synchronized boolean canUse(final S source) {
         if (source instanceof CommandSourceStack) {
             try {
-                ((CommandSourceStack) source).currentCommand = this;
+                ((CommandSourceStack) source).currentCommand.put(Thread.currentThread(), this); // Paper - Thread Safe Vanilla Command permission checking
                 return this.requirement.test(source);
             } finally {
-                ((CommandSourceStack) source).currentCommand = null;
+                ((CommandSourceStack) source).currentCommand.remove(Thread.currentThread()); // Paper - Thread Safe Vanilla Command permission checking
             }
         }
         // CraftBukkit end
diff --git a/src/main/java/net/minecraft/commands/CommandSourceStack.java b/src/main/java/net/minecraft/commands/CommandSourceStack.java
index c772fa3b7a1276b0b41c45c6e0f5584b9c3a90cd..55c394fb00d0c7caee3a06720c37f04db571fe93 100644
--- a/src/main/java/net/minecraft/commands/CommandSourceStack.java
+++ b/src/main/java/net/minecraft/commands/CommandSourceStack.java
@@ -64,7 +64,7 @@ public class CommandSourceStack implements ExecutionCommandSource<CommandSourceS
     private final Vec2 rotation;
     private final CommandSigningContext signingContext;
     private final TaskChainer chatMessageChainer;
-    public volatile CommandNode currentCommand; // CraftBukkit
+    public java.util.Map<Thread, CommandNode> currentCommand = new java.util.concurrent.ConcurrentHashMap<>(); // CraftBukkit // Paper - Thread Safe Vanilla Command permission checking
     public boolean bypassSelectorPermissions = false; // Paper - add bypass for selector permissions
 
     public CommandSourceStack(CommandSource output, Vec3 pos, Vec2 rot, ServerLevel world, int level, String name, Component displayName, MinecraftServer server, @Nullable Entity entity) {
@@ -193,9 +193,11 @@ public class CommandSourceStack implements ExecutionCommandSource<CommandSourceS
     @Override
     public boolean hasPermission(int level) {
         // CraftBukkit start
-        CommandNode currentCommand = this.currentCommand;
+        // Paper start - Thread Safe Vanilla Command permission checking
+        CommandNode currentCommand = this.currentCommand.get(Thread.currentThread());
         if (currentCommand != null) {
             return this.hasPermission(level, org.bukkit.craftbukkit.command.VanillaCommandWrapper.getPermission(currentCommand));
+            // Paper end - Thread Safe Vanilla Command permission checking
         }
         // CraftBukkit end