From b972a78e17beeb997d809d87f2e422e6622efd52 Mon Sep 17 00:00:00 2001
From: Guido van Rossum <guido@python.org>
Date: Sat, 21 Jul 2007 00:25:15 +0000
Subject: SF patch# 1757683 by Alexandre Vassalotti.  Add support for
 seeking/writing beyond EOF to io.BytesIO.

---
 Lib/io.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Lib/io.py b/Lib/io.py
index ed94665..0054d42 100644
--- a/Lib/io.py
+++ b/Lib/io.py
@@ -659,6 +659,11 @@ class BytesIO(BufferedIOBase):
             raise ValueError("write to closed file")
         n = len(b)
         newpos = self._pos + n
+        if newpos > len(self._buffer):
+            # Inserts null bytes between the current end of the file
+            # and the new write position.
+            padding = '\x00' * (newpos - len(self._buffer) - n)
+            self._buffer[self._pos:newpos - n] = padding
         self._buffer[self._pos:newpos] = b
         self._pos = newpos
         return n
-- 
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