sys/mprotect.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 <errno.h>
  24 #include <unistd.h>
  25 #include <sys/types.h>
  26 #include <sys/mman.h>
  27
  28 /*
  29  * Stub function to account for the differences in standard compliance
  30  * while maintaining binary backward compatibility.
  31  *
  32  * This is only the legacy behavior.
  33  */
  34 extern int __mprotect(void *, size_t, int);
  35
  36 int
  37 mprotect(void *addr, size_t len, int prot)
  38 {
  39         void    *aligned_addr;
  40         int     page_mask;
  41         size_t  offset;
  42         int     rv;
  43
  44         /*
  45          * Page-align "addr" since the system now requires it
  46          * for standards compliance.
  47          * Update "len" to reflect the alignment.
  48          */
  49         page_mask = getpagesize() - 1;
  50         offset = ((uintptr_t) addr) & page_mask;
  51         aligned_addr = (void *) (((uintptr_t) addr) & ~page_mask);
  52         len += offset;
  53         rv = __mprotect(aligned_addr, len, prot);
  54         if (rv == -1 && errno == ENOMEM) {
  55                 /*
  56                  * Standards now require that we return ENOMEM if there was
  57                  * a hole in the address range.  Panther and earlier used
  58                  * to return an EINVAL error, so honor backwards compatibility.
  59                  */
  60                 errno = EINVAL;
  61         }
  62         return rv;
  63 }