Implement phpGH-15483: Use C23 memset_explicit() for ZEND_SECURE_ZERO() if available (php#18713)

Author: ndossche

Zend/zend_portability.h

@@ -496,6 +496,8 @@ extern "C++" {
 
 #ifdef ZEND_WIN32
 #define ZEND_SECURE_ZERO(var, size) RtlSecureZeroMemory((var), (size))
+#elif defined(HAVE_MEMSET_EXPLICIT)
+#define ZEND_SECURE_ZERO(var, size) memset_explicit((var), 0, (size))
 #else
 #define ZEND_SECURE_ZERO(var, size) explicit_bzero((var), (size))
 #endif

configure.ac

@@ -564,6 +564,7 @@ AC_CHECK_FUNCS(m4_normalize([
   memmem
   mempcpy
   memrchr
+  memset_explicit
   mkstemp
   mmap
   nice

main/explicit_bzero.c

@@ -28,8 +28,10 @@
 
 PHPAPI void php_explicit_bzero(void *dst, size_t siz)
 {
-#ifdef HAVE_EXPLICIT_MEMSET
-    explicit_memset(dst, 0, siz);
+#ifdef HAVE_MEMSET_EXPLICIT /* C23 */
+	memset_explicit(dst, 0, siz);
+#elif defined(HAVE_EXPLICIT_MEMSET) /* NetBSD-specific */
+	explicit_memset(dst, 0, siz);
 #elif defined(PHP_WIN32)
 	RtlSecureZeroMemory(dst, siz);
 #elif defined(__GNUC__)