1/* Copyright (C) 1991-2023 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 <https://www.gnu.org/licenses/>. */
17
18#include <stdio.h>
19#include <stdlib.h>
20#include <unistd.h>
21#include <pointer_guard.h>
22#include <libc-lock.h>
23#include <set-freeres.h>
24#include "exit.h"
25
26/* Initialize the flag that indicates exit function processing
27 is complete. See concurrency notes in stdlib/exit.h where
28 __exit_funcs_lock is declared. */
29bool __exit_funcs_done = false;
30
31/* Call all functions registered with `atexit' and `on_exit',
32 in the reverse of the order in which they were registered
33 perform stdio cleanup, and terminate program execution with STATUS. */
34void
35attribute_hidden
36__run_exit_handlers (int status, struct exit_function_list **listp,
37 bool run_list_atexit, bool run_dtors)
38{
39 /* First, call the TLS destructors. */
40#ifndef SHARED
41 if (&__call_tls_dtors != NULL)
42#endif
43 if (run_dtors)
44 __call_tls_dtors ();
45
46 __libc_lock_lock (__exit_funcs_lock);
47
48 /* We do it this way to handle recursive calls to exit () made by
49 the functions registered with `atexit' and `on_exit'. We call
50 everyone on the list and use the status value in the last
51 exit (). */
52 while (true)
53 {
54 struct exit_function_list *cur;
55
56 restart:
57 cur = *listp;
58
59 if (cur == NULL)
60 {
61 /* Exit processing complete. We will not allow any more
62 atexit/on_exit registrations. */
63 __exit_funcs_done = true;
64 break;
65 }
66
67 while (cur->idx > 0)
68 {
69 struct exit_function *const f = &cur->fns[--cur->idx];
70 const uint64_t new_exitfn_called = __new_exitfn_called;
71
72 switch (f->flavor)
73 {
74 void (*atfct) (void);
75 void (*onfct) (int status, void *arg);
76 void (*cxafct) (void *arg, int status);
77 void *arg;
78
79 case ef_free:
80 case ef_us:
81 break;
82 case ef_on:
83 onfct = f->func.on.fn;
84 arg = f->func.on.arg;
85 PTR_DEMANGLE (onfct);
86
87 /* Unlock the list while we call a foreign function. */
88 __libc_lock_unlock (__exit_funcs_lock);
89 onfct (status, arg);
90 __libc_lock_lock (__exit_funcs_lock);
91 break;
92 case ef_at:
93 atfct = f->func.at;
94 PTR_DEMANGLE (atfct);
95
96 /* Unlock the list while we call a foreign function. */
97 __libc_lock_unlock (__exit_funcs_lock);
98 atfct ();
99 __libc_lock_lock (__exit_funcs_lock);
100 break;
101 case ef_cxa:
102 /* To avoid dlclose/exit race calling cxafct twice (BZ 22180),
103 we must mark this function as ef_free. */
104 f->flavor = ef_free;
105 cxafct = f->func.cxa.fn;
106 arg = f->func.cxa.arg;
107 PTR_DEMANGLE (cxafct);
108
109 /* Unlock the list while we call a foreign function. */
110 __libc_lock_unlock (__exit_funcs_lock);
111 cxafct (arg, status);
112 __libc_lock_lock (__exit_funcs_lock);
113 break;
114 }
115
116 if (__glibc_unlikely (new_exitfn_called != __new_exitfn_called))
117 /* The last exit function, or another thread, has registered
118 more exit functions. Start the loop over. */
119 goto restart;
120 }
121
122 *listp = cur->next;
123 if (*listp != NULL)
124 /* Don't free the last element in the chain, this is the statically
125 allocate element. */
126 free (cur);
127 }
128
129 __libc_lock_unlock (__exit_funcs_lock);
130
131 if (run_list_atexit)
132 call_function_static_weak (_IO_cleanup);
133
134 _exit (status);
135}
136
137
138void
139exit (int status)
140{
141 __run_exit_handlers (status, &__exit_funcs, true, true);
142}
143libc_hidden_def (exit)
144