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 #include <sys/syscall.h>
  27
  28 /*
  29  * Stub function to account for the differences in standard compliance
  30  * while maintaining binary backward compatibility.
  31  */
  32 int
  33 munmap(void *addr, size_t len)
  34 {
  35 #if __DARWIN_UNIX03
  36         return syscall(SYS_munmap, addr, len);
  37 #else   /* !__DARWIN_UNIX03 */
  38         int     page_mask;
  39         size_t  offset;
  40         int     rv;
  41
  42         if (len == 0) {
  43                 /*
  44                  * Standard compliance now requires the system to return EINVAL
  45                  * for munmap(addr, 0).  Return success now to maintain
  46                  * backwards compatibility.
  47                  */
  48                 return 0;
  49         }
  50         /*
  51          * Page-align "addr" since the system now requires it
  52          * for standards compliance.
  53          * Update "len" to reflect the adjustment and still cover the same area.
  54          */
  55         page_mask = getpagesize() - 1;
  56         offset = ((uintptr_t) addr) & page_mask;
  57         addr = (void *) (((uintptr_t) addr) & ~page_mask);
  58         len += offset;
  59         rv = syscall(SYS_munmap, addr, len);
  60         return rv;
  61 #endif  /* !__DARWIN_UNIX03 */
  62 }