From: Volker Lendecke <vl@samba.org>
Date: Fri, 10 Jan 2014 09:45:22 +0000 (+0100)
Subject: talloc: Tune talloc_vasprintf
X-Git-Url: http://git.samba.org/?a=commitdiff_plain;ds=sidebyside;h=593c8103af5a5ed6b3c915369fed5b90efb42c25;p=abartlet%2Fsamba.git%2F.git

talloc: Tune talloc_vasprintf

vsnprintf is significantly more expensive than memcpy. For the
common case where the string we print is less than a kilobyte, avoid
the second vsnprintf.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Thu May 15 12:49:14 CEST 2014 on sn-devel-104
---

diff --git a/lib/talloc/talloc.c b/lib/talloc/talloc.c
index 1cb4d7dead7..2a5406e11d0 100644
--- a/lib/talloc/talloc.c
+++ b/lib/talloc/talloc.c
@@ -2356,11 +2356,11 @@ _PUBLIC_ char *talloc_vasprintf(const void *t, const char *fmt, va_list ap)
 	int len;
 	char *ret;
 	va_list ap2;
-	char c;
+	char buf[1024];
 
 	/* this call looks strange, but it makes it work on older solaris boxes */
 	va_copy(ap2, ap);
-	len = vsnprintf(&c, 1, fmt, ap2);
+	len = vsnprintf(buf, sizeof(buf), fmt, ap2);
 	va_end(ap2);
 	if (unlikely(len < 0)) {
 		return NULL;
@@ -2369,9 +2369,13 @@ _PUBLIC_ char *talloc_vasprintf(const void *t, const char *fmt, va_list ap)
 	ret = (char *)__talloc(t, len+1);
 	if (unlikely(!ret)) return NULL;
 
-	va_copy(ap2, ap);
-	vsnprintf(ret, len+1, fmt, ap2);
-	va_end(ap2);
+	if (len < sizeof(buf)) {
+		memcpy(ret, buf, len+1);
+	} else {
+		va_copy(ap2, ap);
+		vsnprintf(ret, len+1, fmt, ap2);
+		va_end(ap2);
+	}
 
 	_talloc_set_name_const(ret, ret);
 	return ret;