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/*

 * Copyright (c) 1990 Regents of the University of California.

 * All rights reserved.

 *

 * %sccs.include.redist.c%

 *

 * This function is a modified version of atexit.c

 */

/*

FUNCTION

<<on_exit>>---request execution of function with argument at program exit

INDEX

        on_exit

ANSI_SYNOPSIS

        #include <stdlib.h>

        int on_exit (void (*<[function]>)(int, void *), void *<[arg]>);

TRAD_SYNOPSIS

        #include <stdlib.h>

        int on_exit ((<[function]>, <[arg]>)

          void (*<[function]>)(int, void *);

          void *<[arg]>;

DESCRIPTION

You can use <<on_exit>> to enroll functions in a list of functions that

will be called when your program terminates normally.  The argument is

a pointer to a user-defined function which takes two arguments.  The

first is the status code passed to exit and the second argument is of type

pointer to void.  The function must not return a result.  The value

of <[arg]> is registered and passed as the argument to <[function]>.

The functions are kept in a LIFO stack; that is, the last function

enrolled by <<atexit>> or <<on_exit>> will be the first to execute when

your program exits.  You can intermix functions using <<atexit>> and

<<on_exit>>.

There is no built-in limit to the number of functions you can enroll

in this list; however, after every group of 32 functions is enrolled,

<<atexit>>/<<on_exit>> will call <<malloc>> to get space for the next part

of the list.   The initial list of 32 functions is statically allocated, so

you can always count on at least that many slots available.

RETURNS

<<on_exit>> returns <<0>> if it succeeds in enrolling your function,

<<-1>> if it fails (possible only if no space was available for

<<malloc>> to extend the list of functions).

PORTABILITY

<<on_exit>> is a non-standard glibc extension

Supporting OS subroutines required: None

*/

#include <stddef.h>

#include <stdlib.h>

#include "atexit.h"

/*

 * Register a function to be performed at exit.

 */

int

_DEFUN (on_exit,

        (fn, arg),

        _VOID _EXFNPTR(fn, (int, _PTR)) _AND

        _PTR arg)

{

  return __register_exitproc (__et_onexit, (void (*)(void)) fn, arg, NULL);

}