newlib/libc/stdlib/atexit.c

   1 /*
   2  * Copyright (c) 1990 Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * %sccs.include.redist.c%
   6  */
   7
   8 /*
   9 FUNCTION
  10 <<atexit>>---request execution of functions at program exit
  11
  12 INDEX
  13         atexit
  14
  15 SYNOPSIS
  16         #include <stdlib.h>
  17         int atexit (void (*<[function]>)(void));
  18
  19 DESCRIPTION
  20 You can use <<atexit>> to enroll functions in a list of functions that
  21 will be called when your program terminates normally.  The argument is
  22 a pointer to a user-defined function (which must not require arguments and
  23 must not return a result).
  24
  25 The functions are kept in a LIFO stack; that is, the last function
  26 enrolled by <<atexit>> will be the first to execute when your program
  27 exits.
  28
  29 There is no built-in limit to the number of functions you can enroll
  30 in this list; however, after every group of 32 functions is enrolled,
  31 <<atexit>> will call <<malloc>> to get space for the next part of the
  32 list.   The initial list of 32 functions is statically allocated, so
  33 you can always count on at least that many slots available.
  34
  35 RETURNS
  36 <<atexit>> returns <<0>> if it succeeds in enrolling your function,
  37 <<-1>> if it fails (possible only if no space was available for
  38 <<malloc>> to extend the list of functions).
  39
  40 PORTABILITY
  41 <<atexit>> is required by the ANSI standard, which also specifies that
  42 implementations must support enrolling at least 32 functions.
  43
  44 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  45 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  46 */
  47
  48 #include <stdlib.h>
  49 #include "atexit.h"
  50
  51 /*
  52  * Register a function to be performed at exit.
  53  */
  54
  55 int
  56 atexit (void (*fn) (void))
  57 {
  58   return __register_exitproc (__et_atexit, fn, NULL, NULL);
  59 }