PaperMC/patches/server/0997-Fix-PlayerCommandPreprocessEvent-on-signed-commands.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Nassim Jahnke <nassim@njahnke.dev>
Date: Sat, 21 Sep 2024 22:01:52 +0200
Subject: [PATCH] Fix PlayerCommandPreprocessEvent on signed commands


diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index accf3e43f58fe3588578cb15f53695d825e58670..dd8635efd225cef74924db01a84d41cb80e262b9 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -2255,24 +2255,32 @@ public class ServerGamePacketListenerImpl extends ServerCommonPacketListenerImpl
 
         PlayerCommandPreprocessEvent event = new PlayerCommandPreprocessEvent(this.getCraftPlayer(), command, new LazyPlayerSet(this.server));
         this.cserver.getPluginManager().callEvent(event);
-
-        if (event.isCancelled()) {
-            return;
-        }
         command = event.getMessage().substring(1);
 
-        ParseResults<CommandSourceStack> parseresults = this.parseCommand(command);
-        // CraftBukkit end
-
-        Map map;
+        // Paper start - Fix cancellation and message changing
+        ParseResults<CommandSourceStack> parseresults = this.parseCommand(packet.command());
 
+        Map<String, PlayerChatMessage> map;
         try {
-            map = (packet.command().equals(command)) ? this.collectSignedArguments(packet, SignableCommand.of(parseresults), lastSeenMessages) : Collections.emptyMap(); // CraftBukkit
+            // Always parse the original command to add to the chat chain
+            map = this.collectSignedArguments(packet, SignableCommand.of(parseresults), lastSeenMessages);
         } catch (SignedMessageChain.DecodeException signedmessagechain_a) {
             this.handleMessageDecodeFailure(signedmessagechain_a);
             return;
         }
 
+        if (event.isCancelled()) {
+            // Only now are we actually good to return
+            return;
+        }
+
+        // Remove signed parts if the command was changed
+        if (!command.equals(packet.command())) {
+            parseresults = this.parseCommand(command);
+            map = Collections.emptyMap();
+        }
+        // Paper end - Fix cancellation and message changing
+
         CommandSigningContext.SignedArguments commandsigningcontext_a = new CommandSigningContext.SignedArguments(map);
 
         parseresults = Commands.<CommandSourceStack>mapSource(parseresults, (commandlistenerwrapper) -> { // CraftBukkit - decompile error