improve file type check

AssetStudio/AssetsManager.cs

@@ -139,9 +139,6 @@ namespace AssetStudio
                 catch
                 {
                     //Logger.Error($"Unable to load assets file {fileName} from {Path.GetFileName(originalPath)}");
-                }
-                finally
-                {
                     resourceFileReaders.Add(fileName, reader);
                 }
             }
@@ -156,8 +153,16 @@ namespace AssetStudio
                 var bundleFile = new BundleFile(reader, fullName);
                 foreach (var file in bundleFile.fileList)
                 {
-                    var dummyPath = Path.GetDirectoryName(fullName) + "\\" + file.fileName;
+                    var subReader = new EndianBinaryReader(file.stream);
-                    LoadAssetsFromMemory(dummyPath, new EndianBinaryReader(file.stream), parentPath ?? fullName, bundleFile.versionEngine);
+                    if (SerializedFile.IsSerializedFile(subReader))
+                    {
+                        var dummyPath = Path.GetDirectoryName(fullName) + Path.DirectorySeparatorChar + file.fileName;
+                        LoadAssetsFromMemory(dummyPath, subReader, parentPath ?? fullName, bundleFile.versionEngine);
+                    }
+                    else
+                    {
+                        resourceFileReaders.Add(file.fileName, subReader);
+                    }
                 }
             }
             catch
@@ -196,6 +201,9 @@ namespace AssetStudio
                         case FileType.WebFile:
                             LoadWebFile(dummyPath, fileReader);
                             break;
+                        case FileType.ResourceFile:
+                            resourceFileReaders.Add(file.fileName, fileReader);
+                            break;
                     }
                 }
             }

AssetStudio/ImportHelper.cs

@@ -8,7 +8,8 @@ namespace AssetStudio
     {
         AssetsFile,
         BundleFile,
-        WebFile
+        WebFile,
+        ResourceFile
     }
 
     public static class ImportHelper
@@ -96,7 +97,14 @@ namespace AssetStudio
                         {
                             return FileType.WebFile;
                         }
-                        return FileType.AssetsFile;
+                        if (SerializedFile.IsSerializedFile(reader))
+                        {
+                            return FileType.AssetsFile;
+                        }
+                        else
+                        {
+                            return FileType.ResourceFile;
+                        }
                     }
             }
         }

AssetStudio/SerializedFile.cs

@@ -330,5 +330,30 @@ namespace AssetStudio
                 return offset.ToString();
             }
         }
+
+        public static bool IsSerializedFile(EndianBinaryReader reader)
+        {
+            var fileSize = reader.BaseStream.Length;
+            if (fileSize < 16)
+            {
+                return false;
+            }
+            var m_MetadataSize = reader.ReadUInt32();
+            var m_FileSize = reader.ReadUInt32();
+            if (m_FileSize != fileSize)
+            {
+                reader.Position = 0;
+                return false;
+            }
+            var m_Version = reader.ReadUInt32();
+            var m_DataOffset = reader.ReadUInt32();
+            if (m_DataOffset > fileSize)
+            {
+                reader.Position = 0;
+                return false;
+            }
+            reader.Position = 0;
+            return true;
+        }
     }
 }