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// relro_test.cc -- test -z relro for gold

// Copyright 2008 Free Software Foundation, Inc.

// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation; either version 3 of the License, or

// (at your option) any later version.

// This program 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 General Public License for more details.

// You should have received a copy of the GNU General Public License

// along with this program; if not, write to the Free Software

// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

// MA 02110-1301, USA.

#include <cassert>

#include <csignal>

#include <cstdio>

#include <cstdlib>

#include <exception>

#include <stdint.h>

#include <unistd.h>

// This tests we were linked with a script.  If we were linked with a

// script, relro currently does not work.

extern char using_script[] __attribute__ ((weak));

// This code is put into a shared library linked with -z relro.

// i1 and i2 are not relro variables.

int i1 = 1;

static int i2 = 2;

// P1 is a global relro variable.

int* const p1 __attribute__ ((aligned(64))) = &i1;

// P2 is a local relro variable.

int* const p2 __attribute__ ((aligned(64))) = &i2;

// Test symbol addresses.

bool

t1()

{

  if (using_script)

    return true;

  void* i1addr = static_cast<void*>(&i1);

  void* i2addr = static_cast<void*>(&i2);

  const void* p1addr = static_cast<const void*>(&p1);

  const void* p2addr = static_cast<const void*>(&p2);

  // The relro variables should precede the non-relro variables in the

  // memory image.

  assert(i1addr > p1addr);

  assert(i1addr > p2addr);

  assert(i2addr > p1addr);

  assert(i2addr > p2addr);

  // The relro variables should not be on the same page as the

  // non-relro variables.

  const size_t page_size = getpagesize();

  uintptr_t i1page = reinterpret_cast<uintptr_t>(i1addr) & ~ (page_size - 1);

  uintptr_t i2page = reinterpret_cast<uintptr_t>(i2addr) & ~ (page_size - 1);

  uintptr_t p1page = reinterpret_cast<uintptr_t>(p1addr) & ~ (page_size - 1);

  uintptr_t p2page = reinterpret_cast<uintptr_t>(p2addr) & ~ (page_size - 1);

  assert(i1page != p1page);

  assert(i1page != p2page);

  assert(i2page != p1page);

  assert(i2page != p2page);

  return true;

}

// Tell terminate handler that we are throwing from a signal handler.

static bool throwing;

// A signal handler for SIGSEGV.

extern "C"

void

sigsegv_handler(int)

{

  throwing = true;

  throw 0;

}

// The original terminate handler.

std::terminate_handler orig_terminate;

// Throwing an exception out of a signal handler doesn't always work

// reliably.  When that happens the program will call terminate.  We

// set a terminate handler to indicate that the test probably passed.

void

terminate_handler()

{

  if (!throwing)

    {

      orig_terminate();

      ::exit(EXIT_FAILURE);

    }

  fprintf(stderr,

          "relro_test: terminate called due to failure to throw through signal handler\n");

  fprintf(stderr, "relro_test: assuming test succeeded\n");

  ::exit(EXIT_SUCCESS);

}

// Use a separate function to throw the exception, so that we don't

// need to use -fnon-call-exceptions.

void f2() __attribute__ ((noinline));

void

f2()

{

  int** pp1 = const_cast<int**>(&p1);

  *pp1 = &i2;

  // We shouldn't get here--the assignment to *pp1 should write to

  // memory which the dynamic linker marked as read-only, giving us a

  // SIGSEGV, causing sigsegv_handler to be invoked, to throw past us.

  assert(0);

}

// Changing a relro variable should give us a SIGSEGV.

bool

t2()

{

  if (using_script)

    return true;

  signal(SIGSEGV, sigsegv_handler);

  orig_terminate = std::set_terminate(terminate_handler);

  try

    {

      f2();

      return false;

    }

  catch (int i)

    {

      assert(i == 0);

      return true;

    }

}