From 3b63ba9db1c3a6c4c3a6513b1051b48c60d3bb6e Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 11 Jul 2020 03:55:59 -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.

Fixes #3722
---
 ...-Vanilla-Command-permission-checking.patch | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 Spigot-Server-Patches/Thread-Safe-Vanilla-Command-permission-checking.patch

diff --git a/Spigot-Server-Patches/Thread-Safe-Vanilla-Command-permission-checking.patch b/Spigot-Server-Patches/Thread-Safe-Vanilla-Command-permission-checking.patch
new file mode 100644
index 0000000000..dd93281cfc
--- /dev/null
+++ b/Spigot-Server-Patches/Thread-Safe-Vanilla-Command-permission-checking.patch
@@ -0,0 +1,52 @@
+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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/com/mojang/brigadier/tree/CommandNode.java
++++ b/src/main/java/com/mojang/brigadier/tree/CommandNode.java
+@@ -0,0 +0,0 @@ public abstract class CommandNode<S> implements Comparable<CommandNode<S>> {
+         // CraftBukkit start
+         if (source instanceof CommandListenerWrapper) {
+             try {
+-                ((CommandListenerWrapper) source).currentCommand = this;
++                ((CommandListenerWrapper) source).currentCommand.set(this); // Paper
+                 return requirement.test(source);
+             } finally {
+-                ((CommandListenerWrapper) source).currentCommand = null;
++                ((CommandListenerWrapper) source).currentCommand.set(null); // Paper
+             }
+         }
+         // CraftBukkit end
+diff --git a/src/main/java/net/minecraft/server/CommandListenerWrapper.java b/src/main/java/net/minecraft/server/CommandListenerWrapper.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/CommandListenerWrapper.java
++++ b/src/main/java/net/minecraft/server/CommandListenerWrapper.java
+@@ -0,0 +0,0 @@ public class CommandListenerWrapper implements ICompletionProvider, com.destroys
+     private final ResultConsumer<CommandListenerWrapper> l;
+     private final ArgumentAnchor.Anchor m;
+     private final Vec2F n;
+-    public CommandNode currentCommand; // CraftBukkit
++    public ThreadLocal<CommandNode> currentCommand = new ThreadLocal<>(); // CraftBukkit // Paper
+ 
+     public CommandListenerWrapper(ICommandListener icommandlistener, Vec3D vec3d, Vec2F vec2f, WorldServer worldserver, int i, String s, IChatBaseComponent ichatbasecomponent, MinecraftServer minecraftserver, @Nullable Entity entity) {
+         this(icommandlistener, vec3d, vec2f, worldserver, i, s, ichatbasecomponent, minecraftserver, entity, false, (commandcontext, flag, j) -> {
+@@ -0,0 +0,0 @@ public class CommandListenerWrapper implements ICompletionProvider, com.destroys
+     @Override
+     public boolean hasPermission(int i) {
+         // CraftBukkit start
++        // Paper start - fix concurrency issue
++        CommandNode currentCommand = this.currentCommand.get();
+         if (currentCommand != null) {
+             return hasPermission(i, org.bukkit.craftbukkit.command.VanillaCommandWrapper.getPermission(currentCommand));
++            // Paper end
+         }
+         // CraftBukkit end
+