1 files changed, 62 insertions, 0 deletions
diff --git a/compat/getentropy_freebsd.c b/compat/getentropy_freebsd.c
new file mode 100644
index 0000000..30cd68e
--- /dev/null
+++ b/compat/getentropy_freebsd.c
@@ -0,0 +1,62 @@
+/*	$OpenBSD: getentropy_freebsd.c,v 1.3 2016/08/07 03:27:21 tb Exp $	*/
+
+/*
+ * Copyright (c) 2014 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+ * Copyright (c) 2014 Brent Cook <bcook@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Emulation of getentropy(2) as documented at:
+ * http://man.openbsd.org/getentropy.2
+ */
+
+#include <sys/types.h>
+#include <sys/sysctl.h>
+
+#include <errno.h>
+#include <stddef.h>
+
+/*
+ * Derived from lib/libc/gen/arc4random.c from FreeBSD.
+ */
+static size_t
+getentropy_sysctl(u_char *buf, size_t size)
+{
+	int mib[2];
+	size_t len, done;
+
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_ARND;
+	done = 0;
+
+	do {
+		len = size;
+		if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
+			return (done);
+		done += len;
+		buf += len;
+		size -= len;
+	} while (size > 0);
+
+	return (done);
+}
+
+int
+getentropy(void *buf, size_t len)
+{
+	if (len <= 256 && getentropy_sysctl(buf, len) == len)
+		return (0);
+
+	errno = EIO;
+	return (-1);
+}