Still create chunks even if object counting fails

Author: colinator27

UndertaleModLib/UndertaleChunkTypes.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.IO;
 using UndertaleModLib.Models;
+using static UndertaleModLib.UndertaleReader;
 
 namespace UndertaleModLib
 {
@@ -62,23 +63,36 @@ public static UndertaleChunk Unserialize(UndertaleReader reader)
             string name = "(unknown)";
             try
             {
+                // Read name and length
                 name = reader.ReadChars(4);
                 uint length = reader.ReadUInt32();
 
-                UndertaleChunk chunk = reader.undertaleData.FORM.Chunks[name];
+                // Find chunk instance, or create one if not already created (when errors occur during object counting)
+                if (!reader.undertaleData.FORM.Chunks.TryGetValue(name, out UndertaleChunk chunk))
+                {
+                    if (!UndertaleChunkFORM.ChunkConstructors.TryGetValue(name, out Func<UndertaleChunk> instantiator))
+                    {
+                        throw new IOException($"Unknown chunk \"{name}\"");
+                    }
+                    chunk = instantiator();
+                    reader.undertaleData.FORM.Chunks[name] = chunk;
+                }
                 Util.DebugUtil.Assert(chunk.Name == name,
                                       $"Chunk name mismatch: expected \"{name}\", got \"{chunk.Name}\".");
                 chunk.Length = length;
 
+                // Read chunk contents
                 reader.SubmitMessage("Reading chunk " + chunk.Name);
-                var lenReader = reader.EnsureLengthFromHere(chunk.Length);
+                EnsureLengthOperation lenReader = reader.EnsureLengthFromHere(chunk.Length);
                 reader.CopyChunkToBuffer(length);
                 chunk.UnserializeChunk(reader);
 
+                // Process padding
                 reader.SwitchReaderType(false);
                 if (name != "FORM" && name != reader.LastChunkName)
                 {
                     UndertaleGeneralInfo generalInfo = name == "GEN8" ? ((UndertaleChunkGEN8)chunk).Object : reader.undertaleData.GeneralInfo;
+
                     // These versions introduced new padding
                     // all chunks now start on 16-byte boundaries
                     // (but the padding is included with length of previous chunk)
@@ -101,6 +115,7 @@ public static UndertaleChunk Unserialize(UndertaleReader reader)
                     }
                 }
 
+                // Ensure full length was read
                 lenReader.ToHere();
 
                 return chunk;
@@ -119,25 +134,27 @@ public static (uint, UndertaleChunk) CountChunkChildObjects(UndertaleReader read
             string name = "(unknown)";
             try
             {
+                // Read name and length
                 name = reader.ReadChars(4);
                 uint length = reader.ReadUInt32();
 
+                // Create chunk instance
                 if (!UndertaleChunkFORM.ChunkConstructors.TryGetValue(name, out Func<UndertaleChunk> instantiator))
                 {
                     throw new IOException($"Unknown chunk \"{name}\"");
                 }
-
                 UndertaleChunk chunk = instantiator();
                 Util.DebugUtil.Assert(chunk.Name == name,
                                       $"Chunk name mismatch: expected \"{name}\", got \"{chunk.Name}\".");
                 chunk.Length = length;
 
+                // Count objects in chunk
                 long chunkStart = reader.Position;
-
                 reader.SubmitMessage("Counting objects of chunk " + chunk.Name);
                 reader.CopyChunkToBuffer(length);
                 uint count = chunk.UnserializeObjectCount(reader);
 
+                // Advance beyond chunk length (parts of the chunk may have been skipped)
                 reader.SwitchReaderType(false);
                 reader.Position = chunkStart + chunk.Length;