1/* Copyright (C) 1991-2021 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 <sysdep.h>
22#include <libc-lock.h>
23#include "exit.h"
24
25#include "set-hooks.h"
26DEFINE_HOOK (__libc_atexit, (void))
27
28/* Initialize the flag that indicates exit function processing
29 is complete. See concurrency notes in stdlib/exit.h where
30 __exit_funcs_lock is declared. */
31bool __exit_funcs_done = false;
32
33/* Call all functions registered with `atexit' and `on_exit',
34 in the reverse of the order in which they were registered
35 perform stdio cleanup, and terminate program execution with STATUS. */
36void
37attribute_hidden
38__run_exit_handlers (int status, struct exit_function_list **listp,
39 bool run_list_atexit, bool run_dtors)
40{
41 /* First, call the TLS destructors. */
42#ifndef SHARED
43 if (&__call_tls_dtors != NULL)
44#endif
45 if (run_dtors)
46 __call_tls_dtors ();
47
48 __libc_lock_lock (__exit_funcs_lock);
49
50 /* We do it this way to handle recursive calls to exit () made by
51 the functions registered with `atexit' and `on_exit'. We call
52 everyone on the list and use the status value in the last
53 exit (). */
54 while (true)
55 {
56 struct exit_function_list *cur = *listp;
57
58 if (cur == NULL)
59 {
60 /* Exit processing complete. We will not allow any more
61 atexit/on_exit registrations. */
62 __exit_funcs_done = true;
63 break;
64 }
65
66 while (cur->idx > 0)
67 {
68 struct exit_function *const f = &cur->fns[--cur->idx];
69 const uint64_t new_exitfn_called = __new_exitfn_called;
70
71 switch (f->flavor)
72 {
73 void (*atfct) (void);
74 void (*onfct) (int status, void *arg);
75 void (*cxafct) (void *arg, int status);
76 void *arg;
77
78 case ef_free:
79 case ef_us:
80 break;
81 case ef_on:
82 onfct = f->func.on.fn;
83 arg = f->func.on.arg;
84#ifdef PTR_DEMANGLE
85 PTR_DEMANGLE (onfct);
86#endif
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#ifdef PTR_DEMANGLE
95 PTR_DEMANGLE (atfct);
96#endif
97 /* Unlock the list while we call a foreign function. */
98 __libc_lock_unlock (__exit_funcs_lock);
99 atfct ();
100 __libc_lock_lock (__exit_funcs_lock);
101 break;
102 case ef_cxa:
103 /* To avoid dlclose/exit race calling cxafct twice (BZ 22180),
104 we must mark this function as ef_free. */
105 f->flavor = ef_free;
106 cxafct = f->func.cxa.fn;
107 arg = f->func.cxa.arg;
108#ifdef PTR_DEMANGLE
109 PTR_DEMANGLE (cxafct);
110#endif
111 /* Unlock the list while we call a foreign function. */
112 __libc_lock_unlock (__exit_funcs_lock);
113 cxafct (arg, status);
114 __libc_lock_lock (__exit_funcs_lock);
115 break;
116 }
117
118 if (__glibc_unlikely (new_exitfn_called != __new_exitfn_called))
119 /* The last exit function, or another thread, has registered
120 more exit functions. Start the loop over. */
121 continue;
122 }
123
124 *listp = cur->next;
125 if (*listp != NULL)
126 /* Don't free the last element in the chain, this is the statically
127 allocate element. */
128 free (cur);
129 }
130
131 __libc_lock_unlock (__exit_funcs_lock);
132
133 if (run_list_atexit)
134 RUN_HOOK (__libc_atexit, ());
135
136 _exit (status);
137}
138
139
140void
141exit (int status)
142{
143 __run_exit_handlers (status, &__exit_funcs, true, true);
144}
145libc_hidden_def (exit)
146