1 files changed, 57 insertions, 0 deletions

diff --git a/openbsd-compat/explicit_bzero.c b/openbsd-compat/explicit_bzero.c
new file mode 100644
index 0000000..ac64e69
--- /dev/null
+++ b/openbsd-compat/explicit_bzero.c
@@ -0,0 +1,57 @@
+/* OPENBSD ORIGINAL: lib/libc/string/explicit_bzero.c */
+/*      $OpenBSD: explicit_bzero.c,v 1.1 2014/01/22 21:06:45 tedu Exp $ */
+/*
+ * Public domain.
+ * Written by Ted Unangst
+ */
+
+#include "openbsd-compat.h"
+
+#if !defined(HAVE_EXPLICIT_BZERO) && !defined(_WIN32)
+
+#include <string.h>
+
+/*
+ * explicit_bzero - don't let the compiler optimize away bzero
+ */
+
+#ifdef HAVE_MEMSET_S
+
+void
+explicit_bzero(void *p, size_t n)
+{
+        if (n == 0)
+                return;
+        (void)memset_s(p, n, 0, n);
+}
+
+#else /* HAVE_MEMSET_S */
+
+/*
+ * Indirect bzero through a volatile pointer to hopefully avoid
+ * dead-store optimisation eliminating the call.
+ */
+static void (* volatile ssh_bzero)(void *, size_t) = bzero;
+
+void
+explicit_bzero(void *p, size_t n)
+{
+        if (n == 0)
+                return;
+        /*
+         * clang -fsanitize=memory needs to intercept memset-like functions
+         * to correctly detect memory initialisation. Make sure one is called
+         * directly since our indirection trick above successfully confuses it.
+         */
+#if defined(__has_feature)
+# if __has_feature(memory_sanitizer)
+        memset(p, 0, n);
+# endif
+#endif
+
+        ssh_bzero(p, n);
+}
+
+#endif /* HAVE_MEMSET_S */
+
+#endif /* !defined(HAVE_EXPLICIT_BZERO) && !defined(_WIN32) */