From 1e2dc657a15bc05e72f9db96e94f903ce50dd15e Mon Sep 17 00:00:00 2001
From: Yorgos Thessalonikefs <yorgos@nlnetlabs.nl>
Date: Mon, 29 Sep 2025 13:12:27 +0200
Subject: [PATCH] ac_cv_func_malloc_0_nonnull for malloc(0) check (#1351)

- For #1339, use the standard variable ac_cv_func_malloc_0_nonnull for
  the malloc(0) check during configure; patch from Helmut Grohne.
---
 acx_nlnetlabs.m4 | 27 ++++++++++++++++-----------
 configure.ac     | 12 ++++++------
 2 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/acx_nlnetlabs.m4 b/acx_nlnetlabs.m4
index 2005637a3..c8195f5e1 100644
--- a/acx_nlnetlabs.m4
+++ b/acx_nlnetlabs.m4
@@ -2,7 +2,9 @@
 # Copyright 2009, Wouter Wijngaards, NLnet Labs.   
 # BSD licensed.
 #
-# Version 49
+# Version 50
+# 2025-09-29 add ac_cv_func_malloc_0_nonnull as a cache value for the malloc(0)
+#            check by ACX_FUNC_MALLOC.
 # 2025-09-29 add ACX_CHECK_NONSTRING_ATTRIBUTE, AHX_CONFIG_NONSTRING_ATTRIBUTE.
 # 2024-01-16 fix to add -l:libssp.a to -lcrypto link check.
 #	     and check for getaddrinfo with only header.
@@ -1232,8 +1234,9 @@ dnl detect malloc and provide malloc compat prototype.
 dnl $1: unique name for compat code
 AC_DEFUN([ACX_FUNC_MALLOC],
 [
-	AC_MSG_CHECKING([for GNU libc compatible malloc])
-	AC_RUN_IFELSE([AC_LANG_PROGRAM(
+	AC_CACHE_CHECK([for GNU libc compatible malloc],[ac_cv_func_malloc_0_nonnull],
+	[
+		AC_RUN_IFELSE([AC_LANG_PROGRAM(
 [[#if defined STDC_HEADERS || defined HAVE_STDLIB_H
 #include <stdlib.h>
 #else
@@ -1241,14 +1244,16 @@ char *malloc ();
 #endif
 ]], [ if(malloc(0) != 0) return 1;])
 ],
-	[AC_MSG_RESULT([no])
-	AC_LIBOBJ(malloc)
-	AC_DEFINE_UNQUOTED([malloc], [rpl_malloc_$1], [Define if  replacement function should be used.])] ,
-	[AC_MSG_RESULT([yes])
-	AC_DEFINE([HAVE_MALLOC], 1, [If have GNU libc compatible malloc])],
-	[AC_MSG_RESULT([no (crosscompile)])
-	AC_LIBOBJ(malloc)
-	AC_DEFINE_UNQUOTED([malloc], [rpl_malloc_$1], [Define if  replacement function should be used.])] )
+		[ac_cv_func_malloc_0_nonnull=no],
+		[ac_cv_func_malloc_0_nonnull=yes],
+		[ac_cv_func_malloc_0_nonnull="no (crosscompile)"])
+	])
+	AS_IF([test "$ac_cv_func_malloc_0_nonnull" = yes],
+		[AC_DEFINE([HAVE_MALLOC], 1, [If have GNU libc compatible malloc])],
+	[
+		AC_LIBOBJ(malloc)
+		AC_DEFINE_UNQUOTED([malloc], [rpl_malloc_$1], [Define if  replacement function should be used.])
+	])
 ])
 
 dnl Define fallback for fseeko and ftello if needed.
diff --git a/configure.ac b/configure.ac
index b5ff6717f..648040c6d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -635,19 +635,19 @@ AC_ARG_ENABLE(alloc-nonregional, AS_HELP_STRING([--enable-alloc-nonregional],[ e
 if test x_$enable_alloc_nonregional = x_yes; then
 	AC_DEFINE(UNBOUND_ALLOC_NONREGIONAL, 1, [use malloc not regions, for debug use])
 fi
-if test x_$enable_alloc_checks = x_yes; then
+AS_IF([test x_$enable_alloc_checks = x_yes],[
 	AC_DEFINE(UNBOUND_ALLOC_STATS, 1, [use statistics for allocs and frees, for debug use])
 	SLDNS_ALLOCCHECK_EXTRA_OBJ="alloc.lo log.lo"
 	AC_SUBST(SLDNS_ALLOCCHECK_EXTRA_OBJ)
 	ASYNCLOOK_ALLOCCHECK_EXTRA_OBJ="alloc.lo"
 	AC_SUBST(ASYNCLOOK_ALLOCCHECK_EXTRA_OBJ)
-else
-	if test x_$enable_alloc_lite = x_yes; then
+],[
+	AS_IF([test x_$enable_alloc_lite = x_yes],[
 		AC_DEFINE(UNBOUND_ALLOC_LITE, 1, [use to enable lightweight alloc assertions, for debug use])
-	else
+	],[
 		ACX_FUNC_MALLOC([unbound])
-	fi
-fi
+	])
+])
 
 # check windows threads (we use them, not pthreads, on windows).
 if test "$on_mingw" = "yes"; then
-- 
2.47.3