sys/munmap.c

   1 /*
   2  * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 #include <unistd.h>
  24 #include <sys/types.h>
  25 #include <sys/mman.h>
  26
  27 /*
  28  * Stub function to account for the differences in standard compliance
  29  * while maintaining binary backward compatibility.
  30  *
  31  * This is only the legacy behavior.
  32  */
  33 extern int __munmap(void *, size_t);
  34
  35 int
  36 munmap(void *addr, size_t len)
  37 {
  38         int     page_mask;
  39         size_t  offset;
  40
  41         if (len == 0) {
  42                 /*
  43                  * Standard compliance now requires the system to return EINVAL
  44                  * for munmap(addr, 0).  Return success now to maintain
  45                  * backwards compatibility.
  46                  */
  47                 return 0;
  48         }
  49         /*
  50          * Page-align "addr" since the system now requires it
  51          * for standards compliance.
  52          * Update "len" to reflect the adjustment and still cover the same area.
  53          */
  54         page_mask = getpagesize() - 1;
  55         offset = ((uintptr_t) addr) & page_mask;
  56         addr = (void *) (((uintptr_t) addr) & ~page_mask);
  57         len += offset;
  58         return __munmap(addr, len);
  59 }