From 3cda841bed68e55d9f29c1e5023601eafbe39737 Mon Sep 17 00:00:00 2001
From: Tnze <cjd001113@outlook.com>
Date: Sat, 25 Jun 2022 23:02:36 +0800
Subject: [PATCH] Check chunk data index and no longer panic

---
 level/chunk.go |  3 +++
 save/chunk.go  | 10 +++++-----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/level/chunk.go b/level/chunk.go
index 383f5b0..1c97cdb 100644
--- a/level/chunk.go
+++ b/level/chunk.go
@@ -143,6 +143,9 @@ func ChunkFromSave(c *save.Chunk) (*Chunk, error) {
 	sections := make([]Section, secs)
 	for _, v := range c.Sections {
 		i := int32(v.Y) - c.YPos
+		if i < 0 || i >= int32(secs) {
+			return nil, fmt.Errorf("section Y value %d out of bounds", v.Y)
+		}
 		var err error
 		sections[i].BlockCount, sections[i].States, err = readStatesPalette(v.BlockStates.Palette, v.BlockStates.Data)
 		if err != nil {
diff --git a/save/chunk.go b/save/chunk.go
index 9975f2e..d931087 100644
--- a/save/chunk.go
+++ b/save/chunk.go
@@ -13,11 +13,11 @@ import (
 // Chunk is 16* chunk
 type Chunk struct {
 	DataVersion   int32
-	XPos          int32          `nbt:"xPos"`
-	YPos          int32          `nbt:"yPos"`
-	ZPos          int32          `nbt:"zPos"`
-	BlockEntities nbt.RawMessage `nbt:"block_entities"`
-	Structures    nbt.RawMessage `nbt:"structures"`
+	XPos          int32            `nbt:"xPos"`
+	YPos          int32            `nbt:"yPos"`
+	ZPos          int32            `nbt:"zPos"`
+	BlockEntities []nbt.RawMessage `nbt:"block_entities"`
+	Structures    nbt.RawMessage   `nbt:"structures"`
 	Heightmaps    struct {
 		MotionBlocking         []uint64 `nbt:"MOTION_BLOCKING"`
 		MotionBlockingNoLeaves []uint64 `nbt:"MOTION_BLOCKING_NO_LEAVES"`