replace: Add memset_s() if not available

See https://en.cppreference.com/w/c/string/byte/memset

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

3 files changed, 56 insertions, 0 deletions

diff --git a/lib/replace/replace.c b/lib/replace/replace.c
index dc81e9cd5ab..113137c2992 100644
--- a/lib/replace/replace.c
+++ b/lib/replace/replace.c
@@ -947,3 +947,34 @@ void rep_setproctitle_init(int argc, char *argv[], char *envp[])
 {
 }
 #endif
+
+#ifndef HAVE_MEMSET_S
+# ifndef RSIZE_MAX
+#  define RSIZE_MAX (SIZE_MAX >> 1)
+# endif
+
+int rep_memset_s(void *dest, size_t destsz, int ch, size_t count)
+{
+	if (dest == NULL) {
+		return EINVAL;
+	}
+
+	if (destsz > RSIZE_MAX ||
+	    count > RSIZE_MAX ||
+	    count > destsz) {
+		return ERANGE;
+	}
+
+#if defined(HAVE_MEMSET_EXPLICIT)
+	memset_explicit(dest, destsz, ch, count);
+#else /* HAVE_MEMSET_EXPLICIT */
+	memset(dest, ch, count);
+# if defined(HAVE_GCC_VOLATILE_MEMORY_PROTECTION)
+	/* See http://llvm.org/bugs/show_bug.cgi?id=15495 */
+	__asm__ volatile("" : : "g"(dest) : "memory");
+# endif /* HAVE_GCC_VOLATILE_MEMORY_PROTECTION */
+#endif /* HAVE_MEMSET_EXPLICIT */
+
+	return 0;
+}
+#endif /* HAVE_MEMSET_S */
diff --git a/lib/replace/replace.h b/lib/replace/replace.h
index 626d3053029..de4e20c4454 100644
--- a/lib/replace/replace.h
+++ b/lib/replace/replace.h
@@ -36,6 +36,9 @@
 #include <standards.h>
 #endif
 
+/* Needs to be defined before std*.h and string*.h are included */
+#define __STDC_WANT_LIB_EXT1__ 1
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
@@ -925,6 +928,11 @@ void rep_setproctitle(const char *fmt, ...) PRINTF_ATTRIBUTE(1, 2);
 void rep_setproctitle_init(int argc, char *argv[], char *envp[]);
 #endif
 
+#ifndef HAVE_MEMSET_S
+#define memset_s rep_memset_s
+int rep_memset_s(void *dest, size_t destsz, int ch, size_t count);
+#endif
+
 #ifndef FALL_THROUGH
 # ifdef HAVE_FALLTHROUGH_ATTRIBUTE
 #  define FALL_THROUGH __attribute__ ((fallthrough))
diff --git a/lib/replace/wscript b/lib/replace/wscript
index 8e2873424be..8adfffe9584 100644
--- a/lib/replace/wscript
+++ b/lib/replace/wscript
@@ -195,6 +195,23 @@ def configure(conf):
                         'socket nsl', checklibc=True,
                         headers='sys/socket.h netinet/in.h arpa/inet.h netdb.h')
 
+    conf.CHECK_FUNCS('memset_s memset_explicit')
+
+    conf.CHECK_CODE('''
+                    #include <string.h>
+
+                    int main(void)
+                    {
+                        char buf[] = "This is some content";
+                        memset(buf, '\0', sizeof(buf)); __asm__ volatile("" : : "g"(&buf) : "memory");
+                        return 0;
+                    }
+                    ''',
+                    define='HAVE_GCC_VOLATILE_MEMORY_PROTECTION',
+                    addmain=False,
+                    msg='Checking for volatile memory protection',
+                    local_include=False)
+
     # Some old Linux systems have broken header files and
     # miss the IPV6_V6ONLY define in netinet/in.h,
     # but have it in linux/in6.h.