/* Operating system specific code for generic dynamic loader functions.  Linux.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <dl-sysdep.h>

#include <endian.h>

#include <fcntl.h>

#include <stdint.h>

#include <not-cancel.h>

#ifndef MIN

# define MIN(a,b) (((a)<(b))?(a):(b))

#endif

#define DL_SYSDEP_OSCHECK(FATAL)					      \

  do {									      \

    /* Test whether the kernel is new enough.  This test is only performed    \

       if the library is not compiled to run on all kernels.  */	      \

									      \

    int version = _dl_discover_osversion ();				      \

    if (__glibc_likely (version >= 0))					      \

      {									      \

	if (__builtin_expect (GLRO(dl_osversion) == 0, 1)		      \

	    || GLRO(dl_osversion) > version)				      \

	  GLRO(dl_osversion) = version;					      \

									      \

	/* Now we can test with the required version.  */		      \

	if (__LINUX_KERNEL_VERSION > 0 && version < __LINUX_KERNEL_VERSION)   \

	  /* Not sufficent.  */						      \

	  FATAL ("FATAL: kernel too old\n");				      \

      }									      \

    else if (__LINUX_KERNEL_VERSION > 0)				      \

      FATAL ("FATAL: cannot determine kernel version\n");		      \

  } while (0)

static inline uintptr_t __attribute__ ((always_inline))

_dl_setup_stack_chk_guard (void *dl_random)

{

  union

  {

    uintptr_t num;

    unsigned char bytes[sizeof (uintptr_t)];

  } ret;

  /* We need in the moment only 8 bytes on 32-bit platforms and 16

     bytes on 64-bit platforms.  Therefore we can use the data

     directly and not use the kernel-provided data to seed a PRNG.  */

  memcpy (ret.bytes, dl_random, sizeof (ret));

#if BYTE_ORDER == LITTLE_ENDIAN

  ret.num &= ~(uintptr_t) 0xff;

#elif BYTE_ORDER == BIG_ENDIAN

  ret.num &= ~((uintptr_t) 0xff << (8 * (sizeof (ret) - 1)));

#else

# error "BYTE_ORDER unknown"

#endif

  return ret.num;

}

static inline uintptr_t __attribute__ ((always_inline))

_dl_setup_pointer_guard (void *dl_random, uintptr_t stack_chk_guard)

{

  uintptr_t ret;

  memcpy (&ret, (char *) dl_random + sizeof (ret), sizeof (ret));

  return ret;

}