libiberty/xatexit.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 /*
  10
  11 @deftypefun int xatexit (void (*@var{fn}) (void))
  12
  13 Behaves as the standard @code{atexit} function, but with no limit on
  14 the number of registered functions.  Returns 0 on success, or -1 on
  15 failure.  If you use @code{xatexit} to register functions, you must use
  16 @code{xexit} to terminate your program.
  17
  18 @end deftypefun
  19
  20 */
  21
  22 /* Adapted from newlib/libc/stdlib/{,at}exit.[ch].
  23    If you use xatexit, you must call xexit instead of exit.  */
  24
  25 #include "ansidecl.h"
  26 #include "libiberty.h"
  27
  28 #include <stdio.h>
  29
  30 #ifdef __STDC__
  31 #include <stddef.h>
  32 #else
  33 #define size_t unsigned long
  34 #endif
  35
  36 /* For systems with larger pointers than ints, this must be declared.  */
  37 PTR malloc PARAMS ((size_t));
  38
  39 static void xatexit_cleanup PARAMS ((void));
  40
  41 /* Pointer to function run by xexit.  */
  42 extern void (*_xexit_cleanup) PARAMS ((void));
  43
  44 #define XATEXIT_SIZE 32
  45
  46 struct xatexit {
  47         struct  xatexit *next;          /* next in list */
  48         int     ind;                    /* next index in this table */
  49         void    (*fns[XATEXIT_SIZE]) PARAMS ((void));   /* the table itself */
  50 };
  51
  52 /* Allocate one struct statically to guarantee that we can register
  53    at least a few handlers.  */
  54 static struct xatexit xatexit_first;
  55
  56 /* Points to head of LIFO stack.  */
  57 static struct xatexit *xatexit_head = &xatexit_first;
  58
  59 /* Register function FN to be run by xexit.
  60    Return 0 if successful, -1 if not.  */
  61
  62 int
  63 xatexit (fn)
  64      void (*fn) PARAMS ((void));
  65 {
  66   register struct xatexit *p;
  67
  68   /* Tell xexit to call xatexit_cleanup.  */
  69   if (!_xexit_cleanup)
  70     _xexit_cleanup = xatexit_cleanup;
  71
  72   p = xatexit_head;
  73   if (p->ind >= XATEXIT_SIZE)
  74     {
  75       if ((p = (struct xatexit *) malloc (sizeof *p)) == NULL)
  76         return -1;
  77       p->ind = 0;
  78       p->next = xatexit_head;
  79       xatexit_head = p;
  80     }
  81   p->fns[p->ind++] = fn;
  82   return 0;
  83 }
  84
  85 /* Call any cleanup functions.  */
  86
  87 static void
  88 xatexit_cleanup ()
  89 {
  90   register struct xatexit *p;
  91   register int n;
  92
  93   for (p = xatexit_head; p; p = p->next)
  94     for (n = p->ind; --n >= 0;)
  95       (*p->fns[n]) ();
  96 }