Re: [PATCH] index-pack usage of mmap() is unacceptably slower on many OSes other than Linux

On Tue, 19 Dec 2006, Junio C Hamano wrote:

quoted

diff --git a/index-pack.c b/index-pack.c
index 6d6c92b..e08a687 100644
--- a/index-pack.c
+++ b/index-pack.c

@@ -1,3 +1,8 @@
+#define _XOPEN_SOURCE 500
+#include <unistd.h>
+#include <sys/time.h>
+#include <signal.h>
+
 #include "cache.h"
 #include "delta.h"
 #include "pack.h"

@@ -6,8 +11,6 @@
 #include "commit.h"
 #include "tag.h"
 #include "tree.h"
-#include <sys/time.h>
-#include <signal.h>

Most of the rest of the sources seem to do our includes first
and source-file specific system includes at the end.  What's the
rationale for this change?

Because _XOPEN_SOURCE must be defined before including unistd.h 
otherwise pread is not declared and a warning is issued.

Do we need _XOPEN_SOURCE=500 because pread() is XSI?

The pread man page says Unix98.

Also nobody other than convert-objects.c has _XOPEN_SOURCE level
specified.  If _XOPEN_SOURCE matters I wonder if we should do so
in some central place to make it consistent across source files?

Your call I guess.