Re: [PATCH 2/2] nedmalloc: work around overzealous GCC 6 warning

From: René Scharfe <l.s.r@web.de>
Date: Aug 4, 2016, 21:56 UTC
Message-ID: <57A3BA26.5080601@web.de>
In-Reply-To: <57360f4885bdd5c36e190bea288f1e1f7f706071.1470326812.git.johannes.schindelin@gmx.de>

Am 04.08.2016 um 18:07 schrieb Johannes Schindelin:

Show 9 quoted lines

> With GCC 6, the strdup() function is declared with the "nonnull"
> attribute, stating that it is not allowed to pass a NULL value as
> parameter.
>
> In nedmalloc()'s reimplementation of strdup(), Postel's Law is heeded
> and NULL parameters are handled gracefully. GCC 6 complains about that
> now because it thinks that NULL cannot be passed to strdup() anyway.
>
> Let's just shut up GCC >= 6 in that case and go on with our lives.

This version of strdup() is only compiled if nedmalloc is used instead of the system allocator. That means we can't rely on strdup() being able to take NULL -- some (most?) platforms won't like it. Removing the NULL check would be a more general and overall easier way out, no?

But it should check the result of malloc() before copying.
---
  compat/nedmalloc/nedmalloc.c | 8 +++-----
  1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/compat/nedmalloc/nedmalloc.c b/compat/nedmalloc/nedmalloc.c
index a0a16eb..cc18f0c 100644
--- a/compat/nedmalloc/nedmalloc.c
+++ b/compat/nedmalloc/nedmalloc.c
@@ -955,12 +955,10 @@ void **nedpindependent_comalloc(nedpool *p, size_t 
elems, size_t *sizes, void **
   */
  char *strdup(const char *s1)
  {
-	char *s2 = 0;
-	if (s1) {
-		size_t len = strlen(s1) + 1;
-		s2 = malloc(len);
+	size_t len = strlen(s1) + 1;
+	char *s2 = malloc(len);
+	if (s2)
  		memcpy(s2, s1, len);
-	}
  	return s2;
  }
  #endif

-- 
2.9.2