stdlib/atexit.c

   1 /* Copyright (C) 1991 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 Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 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 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <stdlib.h>
  21 #include "exit.h"
  22
  23
  24 /* Register FUNC to be executed by `exit'.  */
  25 int
  26 DEFUN(atexit, (func), void EXFUN((*func), (NOARGS)))
  27 {
  28   struct exit_function *new = __new_exitfn();
  29
  30   if (new == NULL)
  31     return -1;
  32
  33   new->flavor = ef_at;
  34   new->func.at = func;
  35   return 0;
  36 }
  37
  38
  39 static struct exit_function_list fnlist = { NULL, 0, };
  40 struct exit_function_list *__exit_funcs = &fnlist;
  41
  42 struct exit_function *
  43 DEFUN_VOID(__new_exitfn)
  44 {
  45   register struct exit_function_list *l;
  46
  47   for (l = __exit_funcs; l != NULL; l = l->next)
  48     {
  49       register size_t i;
  50       for (i = 0; i < l->idx; ++i)
  51         if (l->fns[i].flavor == ef_free)
  52           return &l->fns[i];
  53       if (l->idx < sizeof(l->fns) / sizeof(l->fns[0]))
  54         return &l->fns[l->idx++];
  55     }
  56
  57   l = (struct exit_function_list *) malloc(sizeof(struct exit_function_list));
  58   if (l == NULL)
  59     return NULL;
  60   l->next = __exit_funcs;
  61   __exit_funcs = l;
  62
  63   l->idx = 1;
  64   return &l->fns[0];
  65 }