1/* Copyright (C) 1999-2016 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
17
18#include <assert.h>
19#include <stdlib.h>
20#include <stdint.h>
21
22#include <libc-lock.h>
23#include "exit.h"
24#include <atomic.h>
25#include <sysdep.h>
26
27#undef __cxa_atexit
28
29
30int
31attribute_hidden
32__internal_atexit (void (*func) (void *), void *arg, void *d,
33 struct exit_function_list **listp)
34{
35 struct exit_function *new = __new_exitfn (listp);
36
37 if (new == NULL)
38 return -1;
39
40#ifdef PTR_MANGLE
41 PTR_MANGLE (func);
42#endif
43 new->func.cxa.fn = (void (*) (void *, int)) func;
44 new->func.cxa.arg = arg;
45 new->func.cxa.dso_handle = d;
46 atomic_write_barrier ();
47 new->flavor = ef_cxa;
48 return 0;
49}
50
51
52/* Register a function to be called by exit or when a shared library
53 is unloaded. This function is only called from code generated by
54 the C++ compiler. */
55int
56__cxa_atexit (void (*func) (void *), void *arg, void *d)
57{
58 return __internal_atexit (func, arg, d, &__exit_funcs);
59}
60libc_hidden_def (__cxa_atexit)
61
62
63/* We change global data, so we need locking. */
64__libc_lock_define_initialized (static, lock)
65
66
67static struct exit_function_list initial;
68struct exit_function_list *__exit_funcs = &initial;
69uint64_t __new_exitfn_called;
70
71struct exit_function *
72__new_exitfn (struct exit_function_list **listp)
73{
74 struct exit_function_list *p = NULL;
75 struct exit_function_list *l;
76 struct exit_function *r = NULL;
77 size_t i = 0;
78
79 __libc_lock_lock (lock);
80
81 for (l = *listp; l != NULL; p = l, l = l->next)
82 {
83 for (i = l->idx; i > 0; --i)
84 if (l->fns[i - 1].flavor != ef_free)
85 break;
86
87 if (i > 0)
88 break;
89
90 /* This block is completely unused. */
91 l->idx = 0;
92 }
93
94 if (l == NULL || i == sizeof (l->fns) / sizeof (l->fns[0]))
95 {
96 /* The last entry in a block is used. Use the first entry in
97 the previous block if it exists. Otherwise create a new one. */
98 if (p == NULL)
99 {
100 assert (l != NULL);
101 p = (struct exit_function_list *)
102 calloc (1, sizeof (struct exit_function_list));
103 if (p != NULL)
104 {
105 p->next = *listp;
106 *listp = p;
107 }
108 }
109
110 if (p != NULL)
111 {
112 r = &p->fns[0];
113 p->idx = 1;
114 }
115 }
116 else
117 {
118 /* There is more room in the block. */
119 r = &l->fns[i];
120 l->idx = i + 1;
121 }
122
123 /* Mark entry as used, but we don't know the flavor now. */
124 if (r != NULL)
125 {
126 r->flavor = ef_us;
127 ++__new_exitfn_called;
128 }
129
130 __libc_lock_unlock (lock);
131
132 return r;
133}
134