sysdeps/mach/readonly-area.c

   1 /* Test if a memory region is wholly unwritable.  Mach version.
   2    Copyright (C) 2004-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <stdlib.h>
  20 #include <stdint.h>
  21 #include <mach.h>
  22
  23 /* Return 1 if the whole area PTR .. PTR+SIZE is not writable.
  24    Return -1 if it is writable.  */
  25
  26 int
  27 __readonly_area (const char *ptr, size_t size)
  28 {
  29   vm_address_t region_address = (uintptr_t) ptr;
  30   vm_size_t region_length = size;
  31   vm_prot_t protection;
  32   vm_prot_t max_protection;
  33   vm_inherit_t inheritance;
  34   boolean_t is_shared;
  35   mach_port_t object_name;
  36   vm_offset_t offset;
  37
  38   while (__vm_region (__mach_task_self (),
  39                       &region_address, &region_length,
  40                       &protection, &max_protection, &inheritance, &is_shared,
  41                       &object_name, &offset) == KERN_SUCCESS
  42          && region_address <= (uintptr_t) ptr)
  43     {
  44       region_address += region_length;
  45       if (region_address < (uintptr_t) ptr)
  46         continue;
  47
  48       if (protection & VM_PROT_WRITE)
  49         return -1;
  50
  51       if (region_address - (uintptr_t) ptr >= size)
  52         break;
  53     }
  54
  55   return 1;
  56 }