From aece9a43678dd1ab14316a385ee1599cd31e3011 Mon Sep 17 00:00:00 2001
From: oetiker <oetiker@a5681a0c-68f1-0310-ab6d-d61299d08faa>
Date: Thu, 6 Sep 2007 08:42:22 +0000
Subject: [PATCH] * mimic write() and read() even better -- Bernhard Fischer

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@1198 a5681a0c-68f1-0310-ab6d-d61299d08faa
---
 src/rrd_open.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/rrd_open.c b/src/rrd_open.c
index c6a2d7d..b9885aa 100644
--- a/src/rrd_open.c
+++ b/src/rrd_open.c
@@ -469,7 +469,7 @@ inline ssize_t rrd_read(
 
 /* write count bytes from buffer buf to the current position
  * rrd_file->pos of rrd_file->fd.
- * Returns the number of bytes written.  */
+ * Returns the number of bytes written or <0 on error.  */
 
 inline ssize_t rrd_write(
     rrd_file_t *rrd_file,
@@ -477,6 +477,10 @@ inline ssize_t rrd_write(
     size_t count)
 {
 #ifdef HAVE_MMAP
+    if (count == 0)
+       return 0;
+    if (buf == NULL)
+       return -1 /* EINVAL */
     memcpy(rrd_file->file_start + rrd_file->pos, buf, count);
     rrd_file->pos += count;
     return count;       /* mimmic write() semantics */
-- 
2.11.0