glibc/stdlib/atexit.c

91 lines
2.1 KiB
C

/* Copyright (C) 1991, 1996, 1999 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <bits/libc-lock.h>
#include <stdlib.h>
#include "exit.h"
/* Register FUNC to be executed by `exit'. */
int
atexit (void (*func) (void))
{
struct exit_function *new = __new_exitfn ();
if (new == NULL)
return -1;
new->flavor = ef_at;
new->func.at = func;
return 0;
}
/* We change global data, so we need locking. */
__libc_lock_define_initialized (static, lock)
static struct exit_function_list initial;
struct exit_function_list *__exit_funcs = &initial;
struct exit_function *
__new_exitfn (void)
{
struct exit_function_list *l;
size_t i = 0;
__libc_lock_lock (lock);
for (l = __exit_funcs; l != NULL; l = l->next)
{
for (i = 0; i < l->idx; ++i)
if (l->fns[i].flavor == ef_free)
break;
if (i < l->idx)
break;
if (l->idx < sizeof (l->fns) / sizeof (l->fns[0]))
{
i = l->idx++;
break;
}
}
if (l == NULL)
{
l = (struct exit_function_list *)
malloc (sizeof (struct exit_function_list));
if (l != NULL)
{
l->next = __exit_funcs;
__exit_funcs = l;
l->idx = 1;
i = 0;
}
}
/* Mark entry as used, but we don't know the flavor now. */
if (l != NULL)
l->fns[i].flavor = ef_us;
__libc_lock_unlock (lock);
return l == NULL ? NULL : &l->fns[i];
}