glibc/include/register-atfork.h

/* Internal pthread_atfork definitions.
   Copyright (C) 2021-2023 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/>.  */

#ifndef _REGISTER_ATFORK_H
#define _REGISTER_ATFORK_H

/* Elements of the fork handler lists.  */
struct fork_handler
{
  void (*prepare_handler) (void);
  void (*parent_handler) (void);
  void (*child_handler) (void);
  void *dso_handle;
  uint64_t id;
};

/* Function to call to unregister fork handlers.  */
extern void __unregister_atfork (void *dso_handle) attribute_hidden;
#define UNREGISTER_ATFORK(dso_handle) __unregister_atfork (dso_handle)

enum __run_fork_handler_type
{
  atfork_run_prepare,
  atfork_run_child,
  atfork_run_parent
};

/* Run the atfork prepare handlers in the reverse order of registration and
   return the ID of the last registered handler.  If DO_LOCKING is true, the
   internal lock is held locked upon return.  */
extern uint64_t __run_prefork_handlers (_Bool do_locking) attribute_hidden;

/* Given a handler type (parent or child), run all the atfork handlers in
   the order of registration up to and including the handler with id equal
   to LASTRUN.  If DO_LOCKING is true, the internal lock is unlocked prior
   to return.  */
extern void __run_postfork_handlers (enum __run_fork_handler_type who,
                                     _Bool do_locking,
                                     uint64_t lastrun) attribute_hidden;

/* C library side function to register new fork handlers.  */
extern int __register_atfork (void (*__prepare) (void),
			      void (*__parent) (void),
			      void (*__child) (void),
			      void *dso_handle);
libc_hidden_proto (__register_atfork)

#endif