From d9e749a4f00e14e4c137f6d7c367774732deae25 Mon Sep 17 00:00:00 2001
From: Brokkonaut <hannos17@gmx.de>
Date: Sat, 20 Oct 2018 03:45:34 +0200
Subject: [PATCH] Don't modify item tag if interaction is canceled

The item tag is stored before executing the interaction and restored before handling the
resulting events. If the event was not canceled and the ItemStack is not modified in the
event, the new tag is set back to the new one afterwards. This is similar to the handling
of the item amount.

This fixes a bug where tools lose durability when the interaction is canceled and another bug
where tools become completely repaired when they should break but the interaction was canceled.

diff --git a/src/main/java/net/minecraft/server/ItemStack.java b/src/main/java/net/minecraft/server/ItemStack.java
index 4d29cb8d8..cb77bc8a5 100644
--- a/src/main/java/net/minecraft/server/ItemStack.java
+++ b/src/main/java/net/minecraft/server/ItemStack.java
@@ -168,6 +168,7 @@ public final class ItemStack {
         } else {
             // CraftBukkit start - handle all block place event logic here
             int oldCount = this.getCount();
+            NBTTagCompound oldTag = this.tag != null ? this.tag.clone() : null; // Paper - capture old tag
             World world = itemactioncontext.getWorld();
 
             if (!(this.getItem() instanceof ItemBucket)) { // if not bucket
@@ -180,7 +181,9 @@ public final class ItemStack {
             Item item = this.getItem();
             EnumInteractionResult enuminteractionresult = item.a(itemactioncontext);
             int newCount = this.getCount();
+            NBTTagCompound newTag = this.tag != null ? this.tag.clone() : null; // Paper - capture modified tag
             this.setCount(oldCount);
+            this.tag = oldTag; // Paper - restore old tag for the event
             world.captureBlockStates = false;
             if (enuminteractionresult == EnumInteractionResult.SUCCESS && world.captureTreeGeneration && world.capturedBlockStates.size() > 0) {
                 world.captureTreeGeneration = false;
@@ -202,8 +205,9 @@ public final class ItemStack {
 
                 if (!fertilizeEvent.isCancelled()) {
                     // Change the stack to its new contents if it hasn't been tampered with.
-                    if (this.getCount() == oldCount) {
+                    if (this.getCount() == oldCount && java.util.Objects.equals(this.tag, oldTag)) { // Paper - compare the tag too
                         this.setCount(newCount);
+                        this.tag = newTag; // Paper - restore modified tag
                     }
                     for (BlockState blockstate : blocks) {
                         blockstate.update(true);
@@ -249,8 +253,9 @@ public final class ItemStack {
                     }
                 } else {
                     // Change the stack to its new contents if it hasn't been tampered with.
-                    if (this.getCount() == oldCount) {
+                    if (this.getCount() == oldCount && java.util.Objects.equals(this.tag, oldTag)) { // Paper - compare the tag too
                         this.setCount(newCount);
+                        this.tag = newTag; // Paper - restore modified tag
                     }
 
                     for (Map.Entry<BlockPosition, TileEntity> e : world.capturedTileEntities.entrySet()) {
-- 
2.19.1