Implement the ZERO_OBJ() solution from Varnish PR #3057.

Fixes #1

src/vmod_file.c

@@ -37,7 +37,6 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <stdlib.h>
-#include <string.h>
 #include <signal.h>
 #include <stdio.h>
 
@@ -46,13 +45,7 @@
 #include "vtim.h"
 #include "vsb.h"
 
-/*
- * Workaround for the difficulties with feature test macros in newer
- * compiler versions, see:
- * https://github.com/varnishcache/varnish-cache/issues/3051
- */
-#undef ZERO_OBJ
-#define ZERO_OBJ(to, sz) (void)memset(to, 0, sz)
+#include "zero_obj.h"
 
 #include "vcc_if.h"
 

src/zero_obj.h

+/*-
+ * Copyright (c) 2019 UPLEX Nils Goroll Systemoptimierung
+ * All rights reserved
+ *
+ * Author: Geoffrey Simmons <geoffrey.simmons@uplex.de>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Workaround for the difficulties with feature test macros in newer
+ * compiler versions, see:
+ * https://github.com/varnishcache/varnish-cache/issues/3051
+ *
+ * This re-implements the solution in:
+ * https://github.com/varnishcache/varnish-cache/pull/3057
+ */
+
+#include <string.h>
+
+#undef ZERO_OBJ
+#define ZERO_OBJ(to, sz)						\
+	do {								\
+		void *(*volatile z_obj)(void *, int, size_t) = memset;	\
+		(void)z_obj(to, 0, sz);					\
+	} while (0)