--- /dev/null
+++ Libc/Libc-583/sys/munmap.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2004 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@
+ */
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+
+/*
+ * Stub function to account for the differences in standard compliance
+ * while maintaining binary backward compatibility.
+ *
+ * This is only the legacy behavior.
+ */
+extern int __munmap(void *, size_t);
+
+int
+munmap(void *addr, size_t len)
+{
+	int	page_mask;
+	size_t	offset;
+
+	if (len == 0) {
+		/*
+		 * Standard compliance now requires the system to return EINVAL
+		 * for munmap(addr, 0).  Return success now to maintain
+		 * backwards compatibility.
+		 */
+		return 0;
+	}
+	/*
+	 * Page-align "addr" since the system now requires it
+	 * for standards compliance.
+	 * Update "len" to reflect the adjustment and still cover the same area.
+	 */
+	page_mask = getpagesize() - 1;
+	offset = ((uintptr_t) addr) & page_mask;
+	addr = (void *) (((uintptr_t) addr) & ~page_mask);
+	len += offset;
+	return __munmap(addr, len);
+}