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 @minus{}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 #ifdef HAVE_CONFIG_H
  26 #include "config.h"
  27 #endif
  28 #include "ansidecl.h"
  29 #include "libiberty.h"
  30
  31 #include <stdio.h>
  32
  33 #include <stddef.h>
  34
  35 #if VMS
  36 #include <stdlib.h>
  37 #include <unixlib.h>
  38 #else
  39 /* For systems with larger pointers than ints, this must be declared.  */
  40 void *malloc (size_t);
  41 #endif
  42
  43 static void xatexit_cleanup (void);
  44
  45 /* Pointer to function run by xexit.  */
  46 extern void (*_xexit_cleanup) (void);
  47
  48 #define XATEXIT_SIZE 32
  49
  50 struct xatexit {
  51         struct  xatexit *next;          /* next in list */
  52         int     ind;                    /* next index in this table */
  53         void    (*fns[XATEXIT_SIZE]) (void);    /* the table itself */
  54 };
  55
  56 /* Allocate one struct statically to guarantee that we can register
  57    at least a few handlers.  */
  58 static struct xatexit xatexit_first;
  59
  60 /* Points to head of LIFO stack.  */
  61 static struct xatexit *xatexit_head = &xatexit_first;
  62
  63 /* Register function FN to be run by xexit.
  64    Return 0 if successful, -1 if not.  */
  65
  66 int
  67 xatexit (void (*fn) (void))
  68 {
  69   register struct xatexit *p;
  70
  71   /* Tell xexit to call xatexit_cleanup.  */
  72   if (!_xexit_cleanup)
  73     _xexit_cleanup = xatexit_cleanup;
  74
  75   p = xatexit_head;
  76   if (p->ind >= XATEXIT_SIZE)
  77     {
  78       if ((p = (struct xatexit *) malloc (sizeof *p)) == NULL)
  79         return -1;
  80       p->ind = 0;
  81       p->next = xatexit_head;
  82       xatexit_head = p;
  83     }
  84   p->fns[p->ind++] = fn;
  85   return 0;
  86 }
  87
  88 /* Call any cleanup functions.  */
  89
  90 static void
  91 xatexit_cleanup (void)
  92 {
  93   register struct xatexit *p;
  94   register int n;
  95
  96   for (p = xatexit_head; p; p = p->next)
  97     for (n = p->ind; --n >= 0;)
  98       (*p->fns[n]) ();
  99 }