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 PTR 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
xatexit(void (* fn)(void))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
xatexit_cleanup(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 }
100