[PATCH] ccan: Fix calling memset with zero length parameter.

[Volker Lendecke]

On Thu, Jul 11, 2013 at 02:04:00PM +0200, Andreas Schneider wrote:
>   2381                   from ../lib/ccan/likely/likely.h:5,
>   2382                   from ../lib/ccan/tally/tally.c:4:
>   2383  In function 'memset',
>   2384      inlined from 'tally_histogram' at ../lib/ccan/tally/tally.c:513:9:
>   2385  /usr/include/bits/string3.h:81:30: warning: call to 
> '__warn_memset_zero_len' declared with attribute warning: memset used with 
> constant zero length parameter; this could be due to transposed parameters 
> [enabled by default]
>   2386         __warn_memset_zero_len ();
>   2387                                ^
> 
> I didn't see how could could be always 0 here but probably count = 0 is what 
> the compiler sees and warns about.

To avoid an additional if-statement, what about the
alternative attached patch?

Volker

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-------------- next part --------------
>From 05eb75a8cd7d6ee9d703bc9c1b7de67cb8cc31d5 Mon Sep 17 00:00:00 2001
From: Volker Lendecke <vl at samba.org>
Date: Thu, 11 Jul 2013 14:57:53 +0200
Subject: [PATCH] ccan: Fix calling memset with zero length parameter

Signed-off-by: Volker Lendecke <vl at samba.org>
---
 lib/ccan/tally/tally.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/ccan/tally/tally.c b/lib/ccan/tally/tally.c
index 774373c..29f0555 100644
--- a/lib/ccan/tally/tally.c
+++ b/lib/ccan/tally/tally.c
@@ -506,11 +506,11 @@ char *tally_histogram(const struct tally *tally,
 
 		if (count > covered) {
 			count -= covered;
+			memset(p, '*', count);
 		} else {
 			count = 0;
 		}
 
-		memset(p, '*', count);
 		p += count;
 		*p = '\n';
 		p++;
-- 
1.7.9.5