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 14ccd0c8f721e9be7dca8a5dcb8ef95b5cd82731..1f4963bf4681a771130abc1da179819626ecfc1f 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 5316f148f3f9128690f019d544e462b042d8d797..f31c5d665678c3163ed4469f8e9d395b890c1bbe 100644
--- a/src/main/java/net/minecraft/commands/CommandSourceStack.java
+++ b/src/main/java/net/minecraft/commands/CommandSourceStack.java
@@ -66,7 +66,7 @@ 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) {
@@ -195,9 +195,11 @@ 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