Fix parsing of multi-byte key prefix values (#71)

* Fix parsing of multi-byte key prefix values

* whitespace

Author: sydp

dfindexeddb/indexeddb/chromium/record.py

@@ -74,10 +74,9 @@ def FromDecoder(
     """
     offset, raw_prefix = decoder.ReadBytes(1)
 
-    database_id_length = (raw_prefix[0] & 0xE0 >> 5) + 1
-    object_store_id_length = (raw_prefix[0] & 0x1C >> 2) + 1
+    database_id_length = ((raw_prefix[0] & 0xE0) >> 5) + 1
+    object_store_id_length = ((raw_prefix[0] & 0x1C) >> 2) + 1
     index_id_length = (raw_prefix[0] & 0x03) + 1
-
     if database_id_length < 1 or database_id_length > 8:
       raise errors.ParserError("Invalid database ID length")
 
@@ -90,7 +89,6 @@ def FromDecoder(
     _, database_id = decoder.DecodeInt(database_id_length, signed=False)
     _, object_store_id = decoder.DecodeInt(object_store_id_length, signed=False)
     _, index_id = decoder.DecodeInt(index_id_length, signed=False)
-
     return cls(
         offset=base_offset + offset,
         database_id=database_id,

tests/dfindexeddb/indexeddb/chromium/record.py

@@ -31,6 +31,33 @@ def test_parse_key_prefix(self):
     parsed_key_prefix = record.KeyPrefix.FromBytes(key_bytes)
     self.assertEqual(parsed_key_prefix, expected_key_prefix)
 
+  def test_parse_key_prefix_multi_byte_database_id(self):
+    """Tests the KeyPrefix class with multi-byte database id."""
+    expected_key_prefix = record.KeyPrefix(
+        offset=0, database_id=257, object_store_id=2, index_id=3
+    )
+    key_bytes = bytes.fromhex("2001010203")
+    parsed_key_prefix = record.KeyPrefix.FromBytes(key_bytes)
+    self.assertEqual(parsed_key_prefix, expected_key_prefix)
+
+  def test_parse_key_prefix_multi_byte_object_store_id(self):
+    """Tests the KeyPrefix class with multi-byte object store id."""
+    expected_key_prefix = record.KeyPrefix(
+        offset=0, database_id=0, object_store_id=257, index_id=3
+    )
+    key_bytes = bytes.fromhex("0400010103")
+    parsed_key_prefix = record.KeyPrefix.FromBytes(key_bytes)
+    self.assertEqual(parsed_key_prefix, expected_key_prefix)
+
+  def test_parse_key_prefix_multi_byte_index_id(self):
+    """Tests the KeyPrefix class with multi-byte index id."""
+    expected_key_prefix = record.KeyPrefix(
+        offset=0, database_id=1, object_store_id=2, index_id=257
+    )
+    key_bytes = bytes.fromhex("0101020101")
+    parsed_key_prefix = record.KeyPrefix.FromBytes(key_bytes)
+    self.assertEqual(parsed_key_prefix, expected_key_prefix)
+
   def test_parse_idbkey(self):
     """Tests the IDBKey class."""
     expected_idbkey = record.IDBKey(