newlib/libc/stdlib/on_exit.c

   1 /*
   2  * Copyright (c) 1990 Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * %sccs.include.redist.c%
   6  *
   7  * This function is a modified version of atexit.c
   8  */
   9
  10 /*
  11 FUNCTION
  12 <<on_exit>>---request execution of function with argument at program exit
  13
  14 INDEX
  15         on_exit
  16
  17 SYNOPSIS
  18         #include <stdlib.h>
  19         int on_exit (void (*<[function]>)(int, void *), void *<[arg]>);
  20
  21 DESCRIPTION
  22 You can use <<on_exit>> to enroll functions in a list of functions that
  23 will be called when your program terminates normally.  The argument is
  24 a pointer to a user-defined function which takes two arguments.  The
  25 first is the status code passed to exit and the second argument is of type
  26 pointer to void.  The function must not return a result.  The value
  27 of <[arg]> is registered and passed as the argument to <[function]>.
  28
  29 The functions are kept in a LIFO stack; that is, the last function
  30 enrolled by <<atexit>> or <<on_exit>> will be the first to execute when
  31 your program exits.  You can intermix functions using <<atexit>> and
  32 <<on_exit>>.
  33
  34 There is no built-in limit to the number of functions you can enroll
  35 in this list; however, after every group of 32 functions is enrolled,
  36 <<atexit>>/<<on_exit>> will call <<malloc>> to get space for the next part
  37 of the list.   The initial list of 32 functions is statically allocated, so
  38 you can always count on at least that many slots available.
  39
  40 RETURNS
  41 <<on_exit>> returns <<0>> if it succeeds in enrolling your function,
  42 <<-1>> if it fails (possible only if no space was available for
  43 <<malloc>> to extend the list of functions).
  44
  45 PORTABILITY
  46 <<on_exit>> is a non-standard glibc extension
  47
  48 Supporting OS subroutines required: None
  49 */
  50
  51 #include <stddef.h>
  52 #include <stdlib.h>
  53 #include "atexit.h"
  54
  55 #ifdef _REENT_SMALL
  56
  57 #include "on_exit_args.h"
  58
  59 /* force linking of static instance of _on_exit_args */
  60 const void * const __on_exit_dummy = &__on_exit_args;
  61
  62 #endif  /* def _REENT_SMALL */
  63
  64 /*
  65  * Register a function to be performed at exit.
  66  */
  67
  68 int
  69 on_exit (void (*fn) (int, void *),
  70         void *arg)
  71 {
  72   return __register_exitproc (__et_onexit, (void (*)(void)) fn, arg, NULL);
  73 }