roken: Add memset_s implementation

Add an implementation of memset_s to roken.

Some optimising compilers may remove the memset() instruction when it
is used immediately before a free, which defeats its purpose if the
intention is to zero memory before returning it to the heap or stack.

C11 added memset_s, provide a fallback in roken so that memset_s can
be used on all platforms.

cf/roken-frag.m4

@@ -351,6 +351,7 @@ AC_BROKEN([					\
 	localtime_r				\
 	lstat					\
 	memmove					\
+	memset_s				\
 	mkstemp					\
 	putenv					\
 	rcmd					\

lib/roken/NTMakefile

@@ -69,6 +69,7 @@ libroken_la_OBJS =			\
 	$(OBJ)\issuid.obj		\
 	$(OBJ)\localtime_r.obj		\
 	$(OBJ)\lstat.obj		\
+	$(OBJ)\memset_s.obj 		\
 	$(OBJ)\mkdir.obj                \
 	$(OBJ)\mini_inetd.obj		\
 	$(OBJ)\mkstemp.obj		\

lib/roken/memset_s.c

@@ -0,0 +1,51 @@
+/***********************************************************************
+ * Copyright (c) 2015, Your File System Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - 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 COPYRIGHT HOLDERS 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 THE
+ * COPYRIGHT HOLDER 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.
+ *
+ **********************************************************************/
+
+#include <config.h>
+#include "roken.h"
+
+int ROKEN_LIB_FUNCTION
+memset_s(void *s, size_t smax, int c, size_t n)
+{
+    volatile unsigned char *p = s;
+
+#ifdef _WIN32
+    if (c == 0) {
+	SecureZeroMemory(s, n);
+	return 0;
+    }
+#endif
+
+    while (n--) 
+    	*p++ = c; 
+
+    return 0;
+}

lib/roken/roken.h.in

@@ -697,6 +697,7 @@ ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL rk_rename(const char *, const char *);
 #define rk_mkdir(__rk_rn_name, __rk_rn_mode) mkdir(__rk_rn_name,__rk_rn_mode)
 #endif
 
+
 #if !defined(HAVE_DAEMON) || defined(NEED_DAEMON_PROTO)
 #ifndef HAVE_DAEMON
 #define daemon rk_daemon
@@ -1176,6 +1177,12 @@ void
 rk_qsort(void *, size_t, size_t, int (*)(const void *, const void *));
 #endif
 
+#ifndef HAVE_MEMSET_S
+#define memset_s rk_memset_s
+ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL memset_s(void *s, size_t smax,
+					int c, size_t n);
+#endif
+
 #if defined(HAVE_ARC4RANDOM)
 #define rk_random() arc4random()
 #elif defined(HAVE_RANDOM)

lib/roken/version-script.map

@@ -80,6 +80,7 @@ HEIMDAL_ROKEN_1.0 {
 		rk_inet_ntop;
 		rk_inet_pton;
 		rk_localtime_r;
+		rk_memset_s;
 		rk_mkdir;
 		rk_mkstemp;
 		rk_pid_file_delete;