Handle invalid and oversized MIX file indexes

src/TSMapEditor/CCEngine/CCFileManager.cs

@@ -93,7 +93,16 @@ private bool LoadMixFile(string name)
                 {
                     // Logger.Log("Loading MIX file " + name + " from existing MIX file " + Path.GetFileName(value.MixFile.FilePath));
                     var mixFile = new MixFile(value.MixFile, value.Offset);
-                    mixFile.Parse();
+
+                    try
+                    {
+                        mixFile.Parse();
+                    }
+                    catch (Exception ex)
+                    {
+                        Logger.Log($"Failed to parse MIX file {name}: {ex.Message}");
+                    }
+
                     AddMix(mixFile);
                     return true;
                 }
@@ -129,7 +138,16 @@ private bool LoadMixFromDirectories(string name)
 
             Logger.Log("Loading MIX file " + name + " from " + searchDir);
             var mixFile = new MixFile();
-            mixFile.Parse(Path.Combine(searchDir, name));
+
+            try
+            {
+                mixFile.Parse(Path.Combine(searchDir, name));
+            }
+            catch (Exception ex)
+            {
+                Logger.Log($"Failed to parse MIX file {name}: {ex.Message}");
+            }
+
             AddMix(mixFile);
 
             return true;

src/TSMapEditor/CCEngine/MixFile.cs

@@ -103,6 +103,11 @@ public void Parse(Stream stream = null)
 
             MixFileHeader header = new MixFileHeader(buffer);
 
+            // A zero file count means the (possibly encrypted) index came out garbage.
+            // Fail loudly rather than silently registering an empty MIX.
+            if (header.FileCount == 0)
+                throw new MixParseException($"Invalid MIX index (fileCount=0, encrypted={isEncrypted}).");
+
             bodyOffset = INDEX_POSITION + MixFileEntry.SIZE_OF_FILE_ENTRY * header.FileCount;
 
             if (isEncrypted)
@@ -259,14 +264,14 @@ public MixFileHeader(byte[] buffer)
             if (buffer.Length < SIZE_OF_HEADER)
                 throw new ArgumentException("buffer is not long enough");
 
-            FileCount = BitConverter.ToInt16(buffer, 0);
+            FileCount = BitConverter.ToUInt16(buffer, 0);
             BodySize = BitConverter.ToInt32(buffer, 2);
         }
 
         /// <summary>
         /// The number of files in the MIX file.
         /// </summary>
-        public short FileCount { get; private set; }
+        public ushort FileCount { get; private set; }
 
         /// <summary>
         /// The size of the MIX file, excluding the header and index.