File reader fixes for verbs

- Fix local file reader to always read in chunks
- Have gzip stream raise an exception if the full data is requested

storage/local.py

@@ -61,9 +61,11 @@ class LocalStorage(BaseStorageV2):
         num_bytes < 0 copy until the stream ends.
     """
     bytes_copied = 0
-    bytes_remaining = num_bytes
-    while bytes_remaining > 0 or num_bytes < 0:
-      size_to_read = min(bytes_remaining, self.buffer_size)
+    while bytes_copied < num_bytes or num_bytes == -1:
+      size_to_read = min(num_bytes - bytes_copied, self.buffer_size)
+      if size_to_read < 0:
+        size_to_read = self.buffer_size
+
       try:
         buf = in_fp.read(size_to_read)
         if not buf:

util/registry/gzipwrap.py

@@ -11,6 +11,9 @@ class GzipWrap(object):
     self.is_done = False
 
   def read(self, size=-1):
+    if size is None or size < 0:
+      raise Exception('Call to GzipWrap with unbound size will result in poor performance')
+
     # If the buffer already has enough bytes, then simply pop them off of
     # the beginning and return them.
     if len(self.buffer) >= size or self.is_done: