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Handle long arrays inside lists in 1.12->1.11.1 #1355

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Merged
kennytv merged 1 commit into from
Oct 11, 2026
Merged

Handle long arrays inside lists in 1.12->1.11.1 #1355

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60 changes: 54 additions & 6 deletions .../viaversion/viabackwards/protocol/v1_12to1_11_1/rewriter/BlockItemPacketRewriter1_12.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,10 @@

package com.viaversion.viabackwards.protocol.v1_12to1_11_1.rewriter;

import com.google.common.primitives.Ints;
import com.viaversion.nbt.tag.CompoundTag;
import com.viaversion.nbt.tag.IntArrayTag;
import com.viaversion.nbt.tag.ListTag;
import com.viaversion.nbt.tag.LongArrayTag;
import com.viaversion.nbt.tag.StringTag;
import com.viaversion.nbt.tag.Tag;
Expand Down Expand Up @@ -230,6 +232,30 @@ private boolean handleNbtToClient(CompoundTag compoundTag, CompoundTag backupTag
backupTag.put(entry.getKey(), fromLongArrayTag(tag));
iterator.remove();
hasLongArrayTag = true;
} else if (entry.getValue() instanceof ListTag<?> tag) {
if (tag.getElementType() == LongArrayTag.class) {
// Lists can't hold mixed tag types, so the whole list has to be removed
ListTag<IntArrayTag> intArrays = new ListTag<>(IntArrayTag.class);
for (Tag longArrayTag : tag) {
intArrays.add(fromLongArrayTag((LongArrayTag) longArrayTag));
}
backupTag.put(entry.getKey(), intArrays);
iterator.remove();
hasLongArrayTag = true;
} else if (tag.getElementType() == CompoundTag.class) {
// Backed up by list index
CompoundTag listBackupTag = new CompoundTag();
for (int i = 0; i < tag.size(); i++) {
CompoundTag nestedBackupTag = new CompoundTag();
if (handleNbtToClient((CompoundTag) tag.get(i), nestedBackupTag)) {
listBackupTag.put(Integer.toString(i), nestedBackupTag);
}
}
if (!listBackupTag.isEmpty()) {
backupTag.put(entry.getKey(), listBackupTag);
hasLongArrayTag = true;
}
}
}
}
return hasLongArrayTag;
Expand All @@ -252,11 +278,33 @@ private boolean handleNbtToClient(CompoundTag compoundTag, CompoundTag backupTag
private void handleNbtToServer(CompoundTag compoundTag, CompoundTag backupTag) {
// Restore the removed long array tags
for (Map.Entry<String, Tag> entry : backupTag) {
if (entry.getValue() instanceof CompoundTag) {
CompoundTag nestedTag = compoundTag.getCompoundTag(entry.getKey());
handleNbtToServer(nestedTag, (CompoundTag) entry.getValue());
} else {
compoundTag.put(entry.getKey(), fromIntArrayTag((IntArrayTag) entry.getValue()));
if (entry.getValue() instanceof CompoundTag nestedBackupTag) {
Tag tag = compoundTag.get(entry.getKey());
if (tag instanceof CompoundTag nestedTag) {
handleNbtToServer(nestedTag, nestedBackupTag);
} else if (tag instanceof ListTag<?> listTag) {
handleListToServer(listTag, nestedBackupTag);
}
} else if (entry.getValue() instanceof IntArrayTag intArrayTag) {
compoundTag.put(entry.getKey(), fromIntArrayTag(intArrayTag));
} else if (entry.getValue() instanceof ListTag<?> intArrays) {
ListTag<LongArrayTag> longArrays = new ListTag<>(LongArrayTag.class);
for (Tag intArrayTag : intArrays) {
if (intArrayTag instanceof IntArrayTag) {
longArrays.add(fromIntArrayTag((IntArrayTag) intArrayTag));
}
}
compoundTag.put(entry.getKey(), longArrays);
}
}
}

private void handleListToServer(ListTag<?> listTag, CompoundTag backupTag) {
for (Map.Entry<String, Tag> entry : backupTag) {
Integer index = Ints.tryParse(entry.getKey());
if (index != null && index >= 0 && index < listTag.size()
&& listTag.get(index) instanceof CompoundTag nestedTag && entry.getValue() instanceof CompoundTag nestedBackupTag) {
handleNbtToServer(nestedTag, nestedBackupTag);
}
}
}
Expand All @@ -275,7 +323,7 @@ private IntArrayTag fromLongArrayTag(LongArrayTag tag) {
private LongArrayTag fromIntArrayTag(IntArrayTag tag) {
long[] longArray = new long[tag.length() / 2];
int[] intArray = tag.getValue();
for (int i = 0, j = 0; i < intArray.length; i += 2, j++) {
for (int i = 0, j = 0; j < longArray.length; i += 2, j++) {
longArray[j] = (long) intArray[i] << 32 | ((long) intArray[i + 1] & 0xFFFFFFFFL);
}
return new LongArrayTag(longArray);
Expand Down