--- diffdir.py~	2007-08-20 17:19:25.000000000 +0200
+++ diffdir.py	2007-09-10 20:41:03.225984300 +0200
@@ -504,8 +504,9 @@
 
 	def get_data_block(self, fp, max_size):
 		"""Return pair (next data block, boolean last data block)"""
-		buf = fp.read(max_size)
-		if len(buf) < max_size:
+		read_size = min(64*1024, max_size)
+		buf = fp.read(read_size)
+		if len(buf) < read_size:
 			if fp.close(): raise DiffDirException("Error closing file")
 			return (buf, 1)
 		else: return (buf, None)