/* Test the interaction of fork and robust mutexes.

   Copyright (C) 2017-2018 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 <errno.h>

#include <stdbool.h>

#include <stdio.h>

#include <support/check.h>

#include <support/test-driver.h>

#include <support/xthread.h>

#include <support/xunistd.h>

#include <sys/mman.h>

/* Data shared between processes. */

struct shared

{

  pthread_mutex_t parent_mutex;

  pthread_mutex_t child_mutex;

};

/* These flags control which mutex settings are enabled in the parent

   and child (separately).  */

enum mutex_bits

  {

    mutex_pshared = 1,

    mutex_robust = 2,

    mutex_pi = 4,

    mutex_check = 8,

    /* All bits combined.  */

    mutex_all_bits = 15,

  };

static void

mutex_init (pthread_mutex_t *mutex, int bits)

{

  pthread_mutexattr_t attr;

  xpthread_mutexattr_init (&attr);

  if (bits & mutex_pshared)

    xpthread_mutexattr_setpshared (&attr, PTHREAD_PROCESS_SHARED);

  if (bits & mutex_robust)

    xpthread_mutexattr_setrobust (&attr, PTHREAD_MUTEX_ROBUST);

  if (bits & mutex_pi)

    xpthread_mutexattr_setprotocol (&attr, PTHREAD_PRIO_INHERIT);

  if (bits & mutex_check)

    xpthread_mutexattr_settype (&attr, PTHREAD_MUTEX_ERRORCHECK);

  xpthread_mutex_init (mutex, &attr);

  xpthread_mutexattr_destroy (&attr);

}

static void

one_test (int parent_bits, int child_bits, int nonshared_bits,

          bool lock_nonshared, bool lock_child)

{

  struct shared *shared = xmmap (NULL, sizeof (*shared),

                                 PROT_READ | PROT_WRITE,

                                 MAP_ANONYMOUS | MAP_SHARED, -1);

  mutex_init (&shared->parent_mutex, parent_bits);

  mutex_init (&shared->child_mutex, child_bits);

  /* Acquire the parent mutex in the parent.  */

  xpthread_mutex_lock (&shared->parent_mutex);

  pthread_mutex_t nonshared_mutex;

  mutex_init (&nonshared_mutex, nonshared_bits);

  if (lock_nonshared)

    xpthread_mutex_lock (&nonshared_mutex);

  pid_t pid = xfork ();

  if (pid == 0)

    {

      /* Child process.  */

      if (lock_child)

        xpthread_mutex_lock (&shared->child_mutex);

      else

        xmunmap (shared, sizeof (*shared));

      if (lock_nonshared)

        /* Reinitialize the non-shared mutex if it was locked in the

           parent.  */

        mutex_init (&nonshared_mutex, nonshared_bits);

      xpthread_mutex_lock (&nonshared_mutex);

      /* For robust mutexes, the _exit call will perform the unlock

         instead.  */

      if (lock_child && !(child_bits & mutex_robust))

        xpthread_mutex_unlock (&shared->child_mutex);

      _exit (0);

    }

  /* Parent process. */

  {

    int status;

    xwaitpid (pid, &status, 0);

    TEST_VERIFY (status == 0);

  }

  if (parent_bits & mutex_check)

    /* Test for expected self-deadlock.  This is only possible to

       detect if the mutex is error-checking.  */

    TEST_VERIFY_EXIT (pthread_mutex_lock (&shared->parent_mutex) == EDEADLK);

  pid = xfork ();

  if (pid == 0)

    {

      /* Child process.  We can perform some checks only if we are

         dealing with process-shared mutexes.  */

      if (parent_bits & mutex_pshared)

        /* It must not be possible to acquire the parent mutex.

           NB: This check touches a mutex which has been acquired in

           the parent at fork time, so it might be deemed undefined

           behavior, pending the resolution of Austin Groups issue

           1112.  */

        TEST_VERIFY_EXIT (pthread_mutex_trylock (&shared->parent_mutex)

                          == EBUSY);

      if (lock_child && (child_bits & mutex_robust))

        {

          if (!(child_bits & mutex_pshared))

            /* No further tests possible.  */

            _exit (0);

          TEST_VERIFY_EXIT (pthread_mutex_lock (&shared->child_mutex)

                            == EOWNERDEAD);

          xpthread_mutex_consistent (&shared->child_mutex);

        }

      else

        /* We did not acquire the lock in the first child process, or

           we unlocked the mutex again because the mutex is not a

           robust mutex.  */

        xpthread_mutex_lock (&shared->child_mutex);

      xpthread_mutex_unlock (&shared->child_mutex);

      _exit (0);

    }

  /* Parent process. */

  {

    int status;

    xwaitpid (pid, &status, 0);

    TEST_VERIFY (status == 0);

  }

  if (lock_nonshared)

    xpthread_mutex_unlock (&nonshared_mutex);

  xpthread_mutex_unlock (&shared->parent_mutex);

  xpthread_mutex_destroy (&shared->parent_mutex);

  xpthread_mutex_destroy (&shared->child_mutex);

  xpthread_mutex_destroy (&nonshared_mutex);

  xmunmap (shared, sizeof (*shared));

}

static int

do_test (void)

{

  for (int parent_bits = 0; parent_bits <= mutex_all_bits; ++parent_bits)

    for (int child_bits = 0; child_bits <= mutex_all_bits; ++child_bits)

      for (int nonshared_bits = 0; nonshared_bits <= mutex_all_bits;

           ++nonshared_bits)

        for (int lock_nonshared = 0; lock_nonshared < 2; ++lock_nonshared)

          for (int lock_child = 0; lock_child < 2; ++lock_child)

            {

              if (test_verbose)

                printf ("info: parent_bits=0x%x child_bits=0x%x"

                        " nonshared_bits=0x%x%s%s\n",

                        parent_bits, child_bits, nonshared_bits,

                        lock_nonshared ? " lock_nonshared" : "",

                        lock_child ? " lock_child" : "");

              one_test (parent_bits, child_bits, nonshared_bits,

                        lock_nonshared, lock_child);

            }

  return 0;

}

#define TIMEOUT 100

#include <support/test-driver.c>