paramiko.sftp_file.prefetch now backwards compatible

1 files changed, 6 insertions, 2 deletions

diff --git a/paramiko/sftp_file.py b/paramiko/sftp_file.py
index fe0f8c79..425a469a 100644
--- a/paramiko/sftp_file.py
+++ b/paramiko/sftp_file.py
@@ -378,8 +378,8 @@ class SFTPFile (BufferedFile):
         .. versionadded:: 1.5
         """
         self.pipelined = pipelined
-    
-    def prefetch(self, file_size):
+
+    def prefetch(self, file_size=None):
         """
         Pre-fetch the remaining contents of this file in anticipation of future
         `.read` calls.  If reading the entire file, pre-fetching can
@@ -393,6 +393,10 @@ class SFTPFile (BufferedFile):
 
         .. versionadded:: 1.5.1
         """
+
+	if file_size is None:
+		file_size = self.stat().st_size;
+
         # queue up async reads for the rest of the file
         chunks = []
         n = self._realpos