Improve SQLite3 parser (#25)

---------

Co-authored-by: Schamper <[email protected]>

dissect/sql/sqlite3.py

@@ -32,7 +32,7 @@ def __init__(self, fh, wal_fh=None):
  if self.header.magic != SQLITE3_HEADER_MAGIC:
  raise InvalidDatabase("Invalid header magic")
 
- self.encoding = ENCODING[self.header.text_encoding]
+ self.encoding = ENCODING.get(self.header.text_encoding, "utf-8")
  self.page_size = self.header.page_size
  if self.page_size == 1:
  self.page_size = 65536
@@ -75,7 +75,9 @@ def indices(self):
  yield Index(self, *cell.values)
 
  def raw_page(self, num):
- if num < 1 or num > self.header.page_count:
+ # Only throw an out of bounds exception if the header contains a page_count.
+ # Some old versions of SQLite3 do not set/update the page_count correctly.
+ if (num < 1 or num > self.header.page_count) and self.header.page_count > 0:
  raise InvalidPageNumber("Page number exceeds boundaries")
  elif num == 1: # Page 1 is root
  self.fh.seek(len(c_sqlite3.header))
@@ -100,8 +102,8 @@ class Column:
  """Describes a column of a sqlite table."""
 
  SPACE = r"\s"
- EXPRESSION = r"\(.+\)"
- STRING = r"['\"].+['\"]"
+ EXPRESSION = r"\(.+?\)"
+ STRING = r"['\"].+?['\"]"
  TOKENIZER_EXPRESSION = re.compile(f"({SPACE}|{EXPRESSION}|{STRING})")
 
  def __init__(self, name: str, description: str):

tests/conftest.py

@@ -11,3 +11,8 @@ def open_data(name: str) -> BinaryIO:
 @pytest.fixture
 def sqlite_db() -> BinaryIO:
  return open_data("data/test.sqlite")
+
+
+@pytest.fixture
+def empty_db() -> BinaryIO:
+ return open_data("data/empty.sqlite")

tests/test_default_values.py

@@ -44,7 +44,9 @@ def test_parse_table_defaults():
  new_test DEFAULT (1),
  extra_test DEFAULT ("hello world"),
  all_tests DEFAULT (-1.1),
- test DEFAULT (x == NULL)
+ test DEFAULT (x == NULL),
+ some_test INTEGER DEFAULT (0) NOT NULL,
+ another_test VARCHAR(1337) DEFAULT ("test") NOT NULL
  );
  """
  table = Table(sqlite=None, type_=None, name=None, table_name=None, page=None, sql=table_definition)
@@ -57,6 +59,8 @@ def test_parse_table_defaults():
  ("extra_test", "hello world"),
  ("all_tests", -1.1),
  ("test", None),
+ ("some_test", 0),
+ ("another_test", "test"),
  ]
  for key, value in assertion_data:
  assert column_name_for_key(table.columns, key).default_value == value

tests/test_sqlite.py

@@ -51,3 +51,10 @@ def test_sqlite(sqlite_db: BinaryIO) -> None:
 )
 def test_sqlite_read_record(input: bytes, encoding: str, expected_output: tuple[list[int], list[Any]]) -> None:
  assert sqlite3.read_record(BytesIO(input), encoding) == expected_output
+
+
+def test_empty(empty_db: BinaryIO) -> None:
+ s = sqlite3.SQLite3(empty_db)
+
+ assert s.encoding == "utf-8"
+ assert len(list(s.tables())) == 0