1.9.27 - BundleFile - alignment fix for Unity 2019.4.X

* BundleFile - check data for block_alignment

* restrict alignment check

* only check alignment data for version < 7

* use correct version check

* improve error message on failed file parsing

* bump version

Author: K0lb3

UnityPy/__init__.py

@@ -1,4 +1,4 @@
-__version__ = "1.9.26"
+__version__ = "1.9.27"
 
 from .environment import Environment
 from .helpers.ArchiveStorageManager import set_assetbundle_decrypt_key

UnityPy/environment.py

@@ -129,8 +129,9 @@ def load_file(
             return f
         except Exception as e:
             # just to be sure
-            # cuz the SerializedFile detection isn't perfect
-            print("Error loading, reverting to EndianBinaryReader:\n", str(e))
+            # because the SerializedFile detection isn't perfect
+            print(f"Error while loading {stream_name}: {e}")
+            print("Interpreting it as ResourceFile...")
             return EndianBinaryReader(file)
 
     def load_zip_file(self, value):

UnityPy/files/BundleFile.py

@@ -23,6 +23,7 @@ class BundleFile(File.File):
     version_player: str
     dataflags: Tuple[ArchiveFlags, ArchiveFlagsOld]
     decryptor: ArchiveStorageManager.ArchiveStorageDecryptor = None
+    _uses_block_alignment: bool = False
 
     def __init__(self, reader: EndianBinaryReader, parent: File, name: str = None):
         super().__init__(parent=parent, name=name)
@@ -109,8 +110,19 @@ def read_fs(self, reader: EndianBinaryReader):
         if self.dataflags & self.dataflags.UsesAssetBundleEncryption:
             self.decryptor = ArchiveStorageManager.ArchiveStorageDecryptor(reader)
 
+        # check if we need to align the reader
+        # - align to 16 bytes and check if all are 0
+        # - if not, reset the reader to the previous position
         if self.version >= 7:
-            reader.align_stream(16)
+            reader.Position = pre_align
+            self._uses_block_alignment = True
+        elif version >= (2019, 4):
+            pre_align = reader.Position
+            align_data = reader.read((16 - pre_align % 16) % 16)
+            if any(align_data):
+                reader.Position = pre_align
+            else:
+                self._uses_block_alignment = True
 
         start = reader.Position
         if (
@@ -360,7 +372,7 @@ def save_fs(self, writer: EndianBinaryWriter, data_flag: int, block_info_flag: i
         # compression and file layout flag
         writer.write_u_int(data_flag)
 
-        if self.version >= 7:
+        if self._uses_block_alignment:
             # UnityFS\x00 - 8
             # size 8
             # comp sizes 4+4