glibc/htl/forward.c

/* Libc stubs for pthread functions.  Hurd pthread version.
   Copyright (C) 2002-2019 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
   <https://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <shlib-compat.h>
#include <pthread-functions.h>
#include <libc-lock.h>
#include <fork.h>

/* Pointers to the libc functions.  */
struct pthread_functions __libc_pthread_functions attribute_hidden;
int __libc_pthread_functions_init attribute_hidden;


#define FORWARD2(name, rettype, decl, params, defaction) \
rettype									      \
name decl								      \
{									      \
  if (!__libc_pthread_functions_init)					      \
    defaction;								      \
									      \
  return PTHFCT_CALL (ptr_##name, params);				      \
}

/* Same as FORWARD2, only without return.  */
#define FORWARD_NORETURN(name, rettype, decl, params, defaction) \
rettype									      \
name decl								      \
{									      \
  if (!__libc_pthread_functions_init)					      \
    defaction;								      \
									      \
  PTHFCT_CALL (ptr_##name, params);					      \
}

#define FORWARD(name, decl, params, defretval) \
  FORWARD2 (name, int, decl, params, return defretval)

FORWARD (pthread_attr_destroy, (pthread_attr_t *attr), (attr), 0)

FORWARD (pthread_attr_init, (pthread_attr_t *attr), (attr), 0)

FORWARD (pthread_attr_getdetachstate,
	 (const pthread_attr_t *attr, int *detachstate), (attr, detachstate),
	 0)
FORWARD (pthread_attr_setdetachstate, (pthread_attr_t *attr, int detachstate),
	 (attr, detachstate), 0)

FORWARD (pthread_attr_getinheritsched,
	 (const pthread_attr_t *attr, int *inherit), (attr, inherit), 0)
FORWARD (pthread_attr_setinheritsched, (pthread_attr_t *attr, int inherit),
	 (attr, inherit), 0)

FORWARD (pthread_attr_getschedparam,
	 (const pthread_attr_t *attr, struct sched_param *param),
	 (attr, param), 0)
FORWARD (pthread_attr_setschedparam,
	 (pthread_attr_t *attr, const struct sched_param *param),
	 (attr, param), 0)

FORWARD (pthread_attr_getschedpolicy,
	 (const pthread_attr_t *attr, int *policy), (attr, policy), 0)
FORWARD (pthread_attr_setschedpolicy, (pthread_attr_t *attr, int policy),
	 (attr, policy), 0)

FORWARD (pthread_attr_getscope,
	 (const pthread_attr_t *attr, int *scope), (attr, scope), 0)
FORWARD (pthread_attr_setscope, (pthread_attr_t *attr, int scope),
	 (attr, scope), 0)


FORWARD (pthread_condattr_destroy, (pthread_condattr_t *attr), (attr), 0)
FORWARD (pthread_condattr_init, (pthread_condattr_t *attr), (attr), 0)


FORWARD (pthread_cond_broadcast, (pthread_cond_t *cond), (cond), 0)
FORWARD (pthread_cond_destroy, (pthread_cond_t *cond), (cond), 0)
FORWARD (pthread_cond_init,
	 (pthread_cond_t *cond, const pthread_condattr_t *cond_attr),
	 (cond, cond_attr), 0)
FORWARD (pthread_cond_signal, (pthread_cond_t *cond), (cond), 0)
FORWARD (pthread_cond_wait, (pthread_cond_t *cond, pthread_mutex_t *mutex),
	 (cond, mutex), 0)
FORWARD (pthread_cond_timedwait,
	 (pthread_cond_t *cond, pthread_mutex_t *mutex,
	  const struct timespec *abstime), (cond, mutex, abstime), 0)

FORWARD (pthread_equal, (pthread_t thread1, pthread_t thread2),
	 (thread1, thread2), 1)


/* Use an alias to avoid warning, as pthread_exit is declared noreturn.  */
FORWARD_NORETURN (__pthread_exit, void, (void *retval), (retval),
		  exit (EXIT_SUCCESS))
strong_alias (__pthread_exit, pthread_exit);


FORWARD (pthread_getschedparam,
	 (pthread_t target_thread, int *policy, struct sched_param *param),
	 (target_thread, policy, param), 0)
FORWARD (pthread_setschedparam,
	 (pthread_t target_thread, int policy,
	  const struct sched_param *param), (target_thread, policy, param), 0)


FORWARD (pthread_mutex_destroy, (pthread_mutex_t *mutex), (mutex), 0)

FORWARD (pthread_mutex_init,
	 (pthread_mutex_t *mutex, const pthread_mutexattr_t *mutexattr),
	 (mutex, mutexattr), 0)

FORWARD (pthread_mutex_lock, (pthread_mutex_t *mutex), (mutex), 0)

FORWARD (pthread_mutex_unlock, (pthread_mutex_t *mutex), (mutex), 0)


FORWARD2 (pthread_self, pthread_t, (void), (), return 0)


FORWARD (__pthread_setcancelstate, (int state, int *oldstate),
	 (state, oldstate), 0)
strong_alias (__pthread_setcancelstate, pthread_setcancelstate);

FORWARD (pthread_setcanceltype, (int type, int *oldtype), (type, oldtype), 0)

struct __pthread_cancelation_handler *dummy_list;
FORWARD2 (__pthread_get_cleanup_stack, struct __pthread_cancelation_handler **,
	  (void), (), return &dummy_list);


/* Fork interaction */

struct atfork
{
  void (*prepare) (void);
  void (*parent) (void);
  void (*child) (void);
  void *dso_handle;
  struct atfork *prev;
  struct atfork *next;
};

/* TODO: better locking */
__libc_lock_define_initialized (static, atfork_lock);
static struct atfork *fork_handlers, *fork_last_handler;

static void
atfork_pthread_prepare (void)
{
  struct atfork *handlers, *last_handler;

  __libc_lock_lock (atfork_lock);
  handlers = fork_handlers;
  last_handler = fork_last_handler;
  __libc_lock_unlock (atfork_lock);

  if (last_handler == NULL)
    return;

  while (1)
    {
      if (last_handler->prepare != NULL)
	last_handler->prepare ();
      if (last_handler == handlers)
	break;
      last_handler = last_handler->prev;
    }
}
text_set_element (_hurd_atfork_prepare_hook, atfork_pthread_prepare);

static void
atfork_pthread_parent (void)
{
  struct atfork *handlers;

  __libc_lock_lock (atfork_lock);
  handlers = fork_handlers;
  __libc_lock_unlock (atfork_lock);

  while (handlers != NULL)
    {
      if (handlers->parent != NULL)
	handlers->parent ();
      handlers = handlers->next;
    }
}
text_set_element (_hurd_atfork_parent_hook, atfork_pthread_parent);

static void
atfork_pthread_child (void)
{
  struct atfork *handlers;

  __libc_lock_lock (atfork_lock);
  handlers = fork_handlers;
  __libc_lock_unlock (atfork_lock);

  while (handlers != NULL)
    {
      if (handlers->child != NULL)
	handlers->child ();
      handlers = handlers->next;
    }
}
text_set_element (_hurd_atfork_child_hook, atfork_pthread_child);

int
__register_atfork (void (*prepare) (void),
		   void (*parent) (void),
		   void (*child) (void),
		   void *dso_handle)
{
  struct atfork *new = malloc (sizeof (*new));
  if (new == NULL)
    return errno;

  new->prepare = prepare;
  new->parent = parent;
  new->child = child;
  new->dso_handle = dso_handle;
  new->prev = NULL;

  __libc_lock_lock (atfork_lock);
  new->next = fork_handlers;
  if (fork_handlers != NULL)
    fork_handlers->prev = new;
  fork_handlers = new;
  if (fork_last_handler == NULL)
    fork_last_handler = new;
  __libc_lock_unlock (atfork_lock);

  return 0;
}
libc_hidden_def (__register_atfork)

void
__unregister_atfork (void *dso_handle)
{
  struct atfork **handlers, *prev = NULL, *next;
  __libc_lock_lock (atfork_lock);
  handlers = &fork_handlers;
  while (*handlers != NULL)
    {
      if ((*handlers)->dso_handle == dso_handle)
	{
	  /* Drop this handler from the list.  */
	  if (*handlers == fork_last_handler)
	    {
	      /* Was last, new last is prev, if any.  */
	      fork_last_handler = prev;
	    }

	  next = (*handlers)->next;
	  if (next != NULL)
	    next->prev = prev;
	  *handlers = next;
	}
      else
	{
	  /* Just proceed to next handler.  */
	  prev = *handlers;
	  handlers = &prev->next;
	}
    }
  __libc_lock_unlock (atfork_lock);
}