[Project] Detect memrchr in systems that supports it

CMakeLists.txt

 CHECK_SYMBOL_EXISTS(sched_yield "sched.h" HAVE_SCHED_YIELD)
 CHECK_SYMBOL_EXISTS(__get_cpuid "cpuid.h" HAVE_GET_CPUID)
 CHECK_SYMBOL_EXISTS(nftw "sys/types.h;ftw.h" HAVE_NFTW)
+CHECK_SYMBOL_EXISTS(memrchr "string.h" HAVE_MEMRCHR)
 IF(ENABLE_PCRE2 MATCHES "ON")
 	LIST(APPEND CMAKE_REQUIRED_INCLUDES "${PCRE_INCLUDE}")
 	CHECK_SYMBOL_EXISTS(PCRE2_CONFIG_JIT "pcre2.h" HAVE_PCRE_JIT)

cmake/OSDep.cmake

 # Platform specific configuration
 IF(CMAKE_SYSTEM_NAME MATCHES "^.*BSD$|DragonFly")
     ADD_COMPILE_OPTIONS(-DFREEBSD -D_BSD_SOURCE)
+    SET(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS} -D_BSD_SOURCE")
     CONFIGURE_FILE(freebsd/rspamd.sh.in freebsd/rspamd @ONLY)
     MESSAGE(STATUS "Configuring for BSD system")
     # Find util library
 
 IF(CMAKE_SYSTEM_NAME STREQUAL "Linux")
     ADD_COMPILE_OPTIONS(-D_GNU_SOURCE -DLINUX)
+    SET(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS} -D_GNU_SOURCE")
     # Workaround with architecture specific includes
     #IF(IS_DIRECTORY "/usr/include/${CMAKE_SYSTEM_PROCESSOR}-linux-gnu/")
     #	INCLUDE_DIRECTORIES("/usr/include/${CMAKE_SYSTEM_PROCESSOR}-linux-gnu/")

config.h.in

 #cmakedefine HAVE_MACHINE_ENDIAN_H  1
 #cmakedefine HAVE_MAXPATHLEN     1
 #cmakedefine HAVE_FMEMOPEN       1
+#cmakedefine HAVE_MEMRCHR        1
 #cmakedefine HAVE_MEMSET_S       1
 #cmakedefine HAVE_MKSTEMP        1
 #cmakedefine HAVE_MMAP_ANON      1

src/libutil/str_util.c

 	ucl_object_emit_full (obj, emit_type, &func, comments);
 }
 
-const void *
+#ifndef HAVE_MEMRCHR
+void *
 rspamd_memrchr (const void *m, gint c, gsize len)
 {
 	const guint8 *p = m;
-	gsize i;
 
-	for (i = len; i > 0; i --) {
+	for (gsize i = len; i > 0; i --) {
 		if (p[i - 1] == c) {
-			return p + i - 1;
+			return (void *)(p + i - 1);
 		}
 	}
 
 	return NULL;
 }
+#endif
 
 struct UConverter *
 rspamd_get_utf8_converter (void)

src/libutil/str_util.h

  * @param len
  * @return pointer to the last occurrence or NULL
  */
-const void *rspamd_memrchr (const void *m, gint c, gsize len);
+#ifdef HAVE_MEMRCHR
+#define rspamd_memrchr memrchr
+#else
+void *rspamd_memrchr (const void *m, gint c, gsize len);
+#endif
 
 /**
  * Return length of memory segment starting in `s` that contains no chars from `e`