From 642a169746796701b79e4110a460bdf56c2e9343 Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Wed, 9 Dec 2009 14:18:32 -0800
Subject: syscalls can return negative i/o counts. fix bugs in ReadAt and
 WriteAt not to include negative counts in return values.

R=rsc
CC=golang-dev
http://codereview.appspot.com/170044
---
 src/pkg/os/file.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'src/pkg/os')

diff --git a/src/pkg/os/file.go b/src/pkg/os/file.go
index 03c6d5701..459b78cc2 100644
--- a/src/pkg/os/file.go
+++ b/src/pkg/os/file.go
@@ -141,11 +141,11 @@ func (file *File) ReadAt(b []byte, off int64) (n int, err Error) {
 		if m == 0 && e == 0 {
 			return n, EOF
 		}
-		n += m;
 		if e != 0 {
 			err = &PathError{"read", file.name, Errno(e)};
 			break;
 		}
+		n += m;
 		b = b[m:];
 		off += int64(m);
 	}
@@ -186,11 +186,11 @@ func (file *File) WriteAt(b []byte, off int64) (n int, err Error) {
 	}
 	for len(b) > 0 {
 		m, e := syscall.Pwrite(file.fd, b, off);
-		n += m;
 		if e != 0 {
 			err = &PathError{"write", file.name, Errno(e)};
 			break;
 		}
+		n += m;
 		b = b[m:];
 		off += int64(m);
 	}
-- 
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