/* Copyright (C) 2002-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.

   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 <assert.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/types.h>

#include <sysdep.h>

#include <libio/libioP.h>

#include <tls.h>

#include <hp-timing.h>

#include <ldsodefs.h>

#include <stdio-lock.h>

#include <atomic.h>

#include <nptl/pthreadP.h>

#include <fork.h>

#include <arch-fork.h>

#include <futex-internal.h>

#include <malloc/malloc-internal.h>

static void

fresetlockfiles (void)

{

  _IO_ITER i;

  for (i = _IO_iter_begin(); i != _IO_iter_end(); i = _IO_iter_next(i))

    if ((_IO_iter_file (i)->_flags & _IO_USER_LOCK) == 0)

      _IO_lock_init (*((_IO_lock_t *) _IO_iter_file(i)->_lock));

}

pid_t

__libc_fork (void)

{

  pid_t pid;

  /* Determine if we are running multiple threads.  We skip some fork

     handlers in the single-thread case, to make fork safer to use in

     signal handlers.  POSIX requires that fork is async-signal-safe,

     but our current fork implementation is not.  */

  bool multiple_threads = THREAD_GETMEM (THREAD_SELF, header.multiple_threads);

  __run_fork_handlers (atfork_run_prepare);

  /* If we are not running multiple threads, we do not have to

     preserve lock state.  If fork runs from a signal handler, only

     async-signal-safe functions can be used in the child.  These data

     structures are only used by unsafe functions, so their state does

     not matter if fork was called from a signal handler.  */

  if (multiple_threads)

    {

      _IO_list_lock ();

      /* Acquire malloc locks.  This needs to come last because fork

	 handlers may use malloc, and the libio list lock has an

	 indirect malloc dependency as well (via the getdelim

	 function).  */

      call_function_static_weak (__malloc_fork_lock_parent);

    }

  pid = arch_fork (&THREAD_SELF->tid);

  if (pid == 0)

    {

      struct pthread *self = THREAD_SELF;

      /* See __pthread_once.  */

      if (__fork_generation_pointer != NULL)

	*__fork_generation_pointer += __PTHREAD_ONCE_FORK_GEN_INCR;

#if HP_TIMING_AVAIL

      /* The CPU clock of the thread and process have to be set to zero.  */

      hp_timing_t now;

      HP_TIMING_NOW (now);

      THREAD_SETMEM (self, cpuclock_offset, now);

      GL(dl_cpuclock_offset) = now;

#endif

#ifdef __NR_set_robust_list

      /* Initialize the robust mutex list setting in the kernel which has

	 been reset during the fork.  We do not check for errors because if

	 it fails here, it must have failed at process startup as well and

	 nobody could have used robust mutexes.

	 Before we do that, we have to clear the list of robust mutexes

	 because we do not inherit ownership of mutexes from the parent.

	 We do not have to set self->robust_head.futex_offset since we do

	 inherit the correct value from the parent.  We do not need to clear

	 the pending operation because it must have been zero when fork was

	 called.  */

# if __PTHREAD_MUTEX_HAVE_PREV

      self->robust_prev = &self->robust_head;

# endif

      self->robust_head.list = &self->robust_head;

# ifdef SHARED

      if (__builtin_expect (__libc_pthread_functions_init, 0))

	PTHFCT_CALL (ptr_set_robust, (self));

# else

      extern __typeof (__nptl_set_robust) __nptl_set_robust

	__attribute__((weak));

      if (__builtin_expect (__nptl_set_robust != NULL, 0))

	__nptl_set_robust (self);

# endif

#endif

      /* Reset the lock state in the multi-threaded case.  */

      if (multiple_threads)

	{

	  /* Release malloc locks.  */

	  call_function_static_weak (__malloc_fork_unlock_child);

	  /* Reset the file list.  These are recursive mutexes.  */

	  fresetlockfiles ();

	  /* Reset locks in the I/O code.  */

	  _IO_list_resetlock ();

	}

      /* Reset the lock the dynamic loader uses to protect its data.  */

      __rtld_lock_initialize (GL(dl_load_lock));

      /* Run the handlers registered for the child.  */

      __run_fork_handlers (atfork_run_child);

    }

  else

    {

      /* Release acquired locks in the multi-threaded case.  */

      if (multiple_threads)

	{

	  /* Release malloc locks, parent process variant.  */

	  call_function_static_weak (__malloc_fork_unlock_parent);

	  /* We execute this even if the 'fork' call failed.  */

	  _IO_list_unlock ();

	}

      /* Run the handlers registered for the parent.  */

      __run_fork_handlers (atfork_run_parent);

    }

  return pid;

}

weak_alias (__libc_fork, __fork)

libc_hidden_def (__fork)

weak_alias (__libc_fork, fork)