1  /* Test if a memory region is wholly unwritable.  Mach version.
       2     Copyright (C) 2004-2023 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     <https://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  }