stdlib/exit.h

   1 /* Copyright (C) 1991-2023 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _EXIT_H
  19 #define _EXIT_H 1
  20
  21 #include <stdbool.h>
  22 #include <stdint.h>
  23 #include <libc-lock.h>
  24
  25 enum
  26 {
  27   ef_free,      /* `ef_free' MUST be zero!  */
  28   ef_us,
  29   ef_on,
  30   ef_at,
  31   ef_cxa
  32 };
  33
  34 struct exit_function
  35   {
  36     /* `flavour' should be of type of the `enum' above but since we need
  37        this element in an atomic operation we have to use `long int'.  */
  38     long int flavor;
  39     union
  40       {
  41         void (*at) (void);
  42         struct
  43           {
  44             void (*fn) (int status, void *arg);
  45             void *arg;
  46           } on;
  47         struct
  48           {
  49             void (*fn) (void *arg, int status);
  50             void *arg;
  51             void *dso_handle;
  52           } cxa;
  53       } func;
  54   };
  55 struct exit_function_list
  56   {
  57     struct exit_function_list *next;
  58     size_t idx;
  59     struct exit_function fns[32];
  60   };
  61
  62 extern struct exit_function_list *__exit_funcs attribute_hidden;
  63 extern struct exit_function_list *__quick_exit_funcs attribute_hidden;
  64 extern uint64_t __new_exitfn_called attribute_hidden;
  65
  66 /* True once all registered atexit/at_quick_exit/onexit handlers have been
  67    called */
  68 extern bool __exit_funcs_done attribute_hidden;
  69
  70 /* This lock protects __exit_funcs, __quick_exit_funcs, __exit_funcs_done
  71    and __new_exitfn_called globals against simultaneous access from
  72    atexit/on_exit/at_quick_exit in multiple threads, and also from
  73    simultaneous access while another thread is in the middle of calling
  74    exit handlers.  See BZ#14333.  Note: for lists, the entire list, and
  75    each associated entry in the list, is protected for all access by this
  76    lock.  */
  77 __libc_lock_define (extern, __exit_funcs_lock);
  78
  79
  80 extern struct exit_function *__new_exitfn (struct exit_function_list **listp)
  81   attribute_hidden;
  82
  83 extern void __run_exit_handlers (int status,
  84                                  struct exit_function_list **listp,
  85                                  bool run_list_atexit, bool run_dtors)
  86   attribute_hidden __attribute__ ((__noreturn__));
  87
  88 extern int __internal_atexit (void (*func) (void *), void *arg, void *d,
  89                               struct exit_function_list **listp)
  90   attribute_hidden;
  91 extern int __cxa_at_quick_exit (void (*func) (void *), void *d);
  92
  93
  94 #endif  /* exit.h  */