fix reading blob chars in text mode using StorageStreamDownloader.read() (#38827)

Author: mlschodkowski

sdk/storage/azure-storage-blob/azure/storage/blob/_download.py

@@ -656,7 +656,7 @@ def read(self, size: int = -1, *, chars: Optional[int] = None) -> T:
         output_stream: Union[BytesIO, StringIO]
         if self._text_mode:
             output_stream = StringIO()
-            size = chars if chars else sys.maxsize
+            size = sys.maxsize if chars is None or chars <= 0 else chars
         else:
             output_stream = BytesIO()
             size = size if size > 0 else sys.maxsize

sdk/storage/azure-storage-blob/azure/storage/blob/aio/_download_async.py

@@ -558,7 +558,7 @@ async def read(self, size: int = -1, *, chars: Optional[int] = None) -> T:
         output_stream: Union[BytesIO, StringIO]
         if self._text_mode:
             output_stream = StringIO()
-            size = chars if chars else sys.maxsize
+            size = sys.maxsize if chars is None or chars <= 0 else chars
         else:
             output_stream = BytesIO()
             size = size if size > 0 else sys.maxsize