--- /dev/null
+++ Libc/Libc-1669.40.2/sys/sigaction.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 1999-2017 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#if __has_include(<CrashReporterClient.h>)
+#include <CrashReporterClient.h>
+#else
+#define CRSetCrashLogMessage(...)
+#endif
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/signal.h>
+#include <errno.h>
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wstrict-prototypes"
+
+extern int __platform_sigaction (int sig,
+		const struct sigaction * __restrict nsv,
+		struct sigaction * __restrict osv);
+
+int
+sigaction (int sig, const struct sigaction * __restrict nsv,
+		struct sigaction * __restrict osv)
+{
+	int ret = __platform_sigaction(sig, nsv, osv);
+#ifdef FEATURE_SIGNAL_RESTRICTION
+	// Note: The "sig != 0" here is to force the compiler to maintain that "sig"
+	// is live, and in a register, after __sigaction so it is visible in the
+	// crashing register state.
+	if (ret == -1 && errno == ENOTSUP && sig != 0) {
+		CRSetCrashLogMessage("sigaction on fatal signals is not supported");
+		__builtin_trap();
+	}
+#endif
+	return ret;
+}
+
+// XXX
+#ifdef __DYNAMIC__
+
+int
+_sigaction_nobind (sig, nsv, osv)
+        int sig;
+	register const struct sigaction *nsv;
+        register struct sigaction *osv;
+{
+    return sigaction(sig, nsv, osv);
+}
+#endif
+
+#pragma clang diagnostic pop