From 9b8eca5826cf32c790bbb1e1f8836dc1754a4ef9 Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <lars.wirzenius@codethink.co.uk>
Date: Tue, 30 Sep 2014 10:17:05 +0100
Subject: xfer-hole: Fix bug in copy_slice_from_file.

os.read is limited to an int in size. copy_slice_from_file was trying
to os.read more than that causing an OverflowError.
---
 xfer-hole | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/xfer-hole b/xfer-hole
index 0d4cee7a..22ee06bf 100755
--- a/xfer-hole
+++ b/xfer-hole
@@ -120,8 +120,14 @@ def make_xfer_instructions(fd):
 
 def copy_slice_from_file(to, fd, start, end):
     safe_lseek(fd, start, os.SEEK_SET)
-    data = os.read(fd, end - start)
-    to.write(data)
+    nbytes = end - start
+    max_at_a_time = 1024**2
+    while nbytes > 0:
+        data = os.read(fd, min(nbytes, max_at_a_time))
+        if not data:
+            break
+        to.write(data)
+        nbytes -= len(data)
     
 
 for kind, start, end in make_xfer_instructions(fd):
-- 
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