properly handle negative read values to address #26

Author: mattsb42-aws

src/aws_encryption_sdk/streaming_client.py

@@ -209,6 +209,10 @@ def read(self, b=None):
         :returns: Processed (encrypted or decrypted) bytes from source stream
         :rtype: bytes
         """
+        # Any negative value for b is interpreted as a full read
+        if b is not None and b < 0:
+            b = None
+
         _LOGGER.debug("Stream read called, requesting %s bytes", b)
         output = io.BytesIO()
         if not self._message_prepped:

test/unit/test_streaming_client_encryption_stream.py

@@ -47,7 +47,6 @@ def _read_bytes(self, b):
 
 
 class TestEncryptionStream(object):
-
     def _mock_key_provider(self):
         mock_key_provider = MagicMock()
         mock_key_provider.__class__ = MasterKeyProvider
@@ -226,7 +225,7 @@ def test_read_closed(self):
 
         excinfo.match("I/O operation on closed file")
 
-    @pytest.mark.parametrize('bytes_to_read', range(1, 11))
+    @pytest.mark.parametrize("bytes_to_read", range(1, 11))
     def test_read_b(self, bytes_to_read):
         mock_stream = MockEncryptionStream(
             source=io.BytesIO(VALUES["data_128"]),
@@ -241,15 +240,16 @@ def test_read_b(self, bytes_to_read):
         assert test == data[:bytes_to_read]
         assert mock_stream.output_buffer == data[bytes_to_read:]
 
-    def test_read_all(self):
+    @pytest.mark.parametrize("bytes_to_read", (None, -1, -99))
+    def test_read_all(self, bytes_to_read):
         mock_stream = MockEncryptionStream(
             source=self.mock_source_stream, key_provider=self.mock_key_provider, mock_read_bytes=sentinel.read_bytes
         )
         mock_stream._stream_length = 5
         mock_stream.output_buffer = b"1234567890"
         mock_stream.source_stream = MagicMock()
         type(mock_stream.source_stream).closed = PropertyMock(side_effect=(False, False, True))
-        test = mock_stream.read()
+        test = mock_stream.read(bytes_to_read)
         assert test == b"1234567890"
 
     def test_read_all_empty_source(self):