sysdeps/generic/dl-osinfo.h

   1 /* Operating system specific code for generic dynamic loader functions.
   2    Copyright (C) 2009, 2011 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <endian.h>
  21 #include <stdint.h>
  22
  23 static inline uintptr_t __attribute__ ((always_inline))
  24 _dl_setup_stack_chk_guard (void *dl_random)
  25 {
  26   union
  27   {
  28     uintptr_t num;
  29     unsigned char bytes[sizeof (uintptr_t)];
  30   } ret = { 0 };
  31
  32   if (dl_random == NULL)
  33     {
  34       ret.bytes[sizeof (ret) - 2] = 255;
  35       ret.bytes[sizeof (ret) - 3] = '\n';
  36     }
  37   else
  38     {
  39       memcpy (ret.bytes, dl_random, sizeof (ret));
  40 #if BYTE_ORDER == LITTLE_ENDIAN
  41       ret.num &= ~0xff;
  42 #elif BYTE_ORDER == BIG_ENDIAN
  43       ret.num &= ~(0xff << (8 * (sizeof (ret) - 1)));
  44 #else
  45 # error "BYTE_ORDER unknown"
  46 #endif
  47     }
  48   return ret.num;
  49 }
  50
  51 static inline uintptr_t __attribute__ ((always_inline))
  52 _dl_setup_pointer_guard (void *dl_random, uintptr_t stack_chk_guard)
  53 {
  54   uintptr_t ret;
  55   if (dl_random == NULL)
  56     ret = stack_chk_guard;
  57   else
  58     memcpy (&ret, (char *) dl_random + sizeof (ret), sizeof (ret));
  59   return ret;
  60 }