1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include "namespace.h"
36 #include <errno.h>
37 #include <link.h>
38 #include <stdbool.h>
39 #include <stddef.h>
40 #include <stdlib.h>
41 #include <unistd.h>
42 #include <pthread.h>
43 #include "atexit.h"
44 #include "un-namespace.h"
45 #include "block_abi.h"
46
47 #include "libc_private.h"
48
49 /**
50 * The _Block_copy() function is provided by the block runtime.
51 */
52 __attribute__((weak)) void*
53 _Block_copy(void*);
54
55 #define ATEXIT_FN_EMPTY 0
56 #define ATEXIT_FN_STD 1
57 #define ATEXIT_FN_CXA 2
58
59 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
60 static void *current_finalize_dso = NULL;
61 static bool call_finalize_again = false;
62
63 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x)
64 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x)
65 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x)
66
67 struct atexit {
68 struct atexit *next; /* next in list */
69 int ind; /* next index in this table */
70 struct atexit_fn {
71 int fn_type; /* ATEXIT_? from above */
72 union {
73 void (*std_func)(void);
74 void (*cxa_func)(void *);
75 } fn_ptr; /* function pointer */
76 void *fn_arg; /* argument for CXA callback */
77 void *fn_dso; /* shared module handle */
78 } fns[ATEXIT_SIZE]; /* the table itself */
79 };
80
81 static struct atexit *__atexit; /* points to head of LIFO stack */
82 typedef DECLARE_BLOCK(void, atexit_block, void);
83
84 int atexit_b(atexit_block);
85 int __cxa_atexit(void (*)(void *), void *, void *);
86
87 /*
88 * Register the function described by 'fptr' to be called at application
89 * exit or owning shared object unload time. This is a helper function
90 * for atexit and __cxa_atexit.
91 */
92 static int
atexit_register(struct atexit_fn * fptr)93 atexit_register(struct atexit_fn *fptr)
94 {
95 static struct atexit __atexit0; /* one guaranteed table */
96 struct atexit *p;
97
98 _MUTEX_LOCK(&atexit_mutex);
99 if ((p = __atexit) == NULL)
100 __atexit = p = &__atexit0;
101 else while (p->ind >= ATEXIT_SIZE) {
102 struct atexit *old__atexit;
103 old__atexit = __atexit;
104 _MUTEX_UNLOCK(&atexit_mutex);
105 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
106 return (-1);
107 _MUTEX_LOCK(&atexit_mutex);
108 if (old__atexit != __atexit) {
109 /* Lost race, retry operation */
110 _MUTEX_UNLOCK(&atexit_mutex);
111 free(p);
112 _MUTEX_LOCK(&atexit_mutex);
113 p = __atexit;
114 continue;
115 }
116 p->ind = 0;
117 p->next = __atexit;
118 __atexit = p;
119 }
120 p->fns[p->ind++] = *fptr;
121 if (current_finalize_dso != NULL &&
122 current_finalize_dso == fptr->fn_dso)
123 call_finalize_again = true;
124 _MUTEX_UNLOCK(&atexit_mutex);
125 return 0;
126 }
127
128 /*
129 * Register a function to be performed at exit.
130 */
131 int
atexit(void (* func)(void))132 atexit(void (*func)(void))
133 {
134 struct atexit_fn fn;
135 int error;
136
137 fn.fn_type = ATEXIT_FN_STD;
138 fn.fn_ptr.std_func = func;
139 fn.fn_arg = NULL;
140 fn.fn_dso = NULL;
141
142 error = atexit_register(&fn);
143 return (error);
144 }
145 __weak_reference(atexit, __libc_atexit);
146
147 /**
148 * Register a block to be performed at exit.
149 */
150 int
atexit_b(atexit_block func)151 atexit_b(atexit_block func)
152 {
153 struct atexit_fn fn;
154 int error;
155 if (_Block_copy == 0) {
156 errno = ENOSYS;
157 return -1;
158 }
159 func = _Block_copy(func);
160
161 // Blocks are not C++ destructors, but they have the same signature (a
162 // single void* parameter), so we can pretend that they are.
163 fn.fn_type = ATEXIT_FN_CXA;
164 fn.fn_ptr.cxa_func = (void(*)(void*))GET_BLOCK_FUNCTION(func);
165 fn.fn_arg = func;
166 fn.fn_dso = NULL;
167
168 error = atexit_register(&fn);
169 return (error);
170 }
171
172 /*
173 * Register a function to be performed at exit or when an shared object
174 * with given dso handle is unloaded dynamically.
175 */
176 int
__cxa_atexit(void (* func)(void *),void * arg,void * dso)177 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
178 {
179 struct atexit_fn fn;
180 int error;
181
182 fn.fn_type = ATEXIT_FN_CXA;
183 fn.fn_ptr.cxa_func = func;
184 fn.fn_arg = arg;
185 fn.fn_dso = dso;
186
187 error = atexit_register(&fn);
188 return (error);
189 }
190
191 #pragma weak __pthread_cxa_finalize
192 void __pthread_cxa_finalize(const struct dl_phdr_info *);
193
194 static int global_exit;
195
196 /*
197 * Call all handlers registered with __cxa_atexit for the shared
198 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining
199 * handlers are called.
200 */
201 void
__cxa_finalize(void * dso)202 __cxa_finalize(void *dso)
203 {
204 struct dl_phdr_info phdr_info;
205 struct atexit *p;
206 struct atexit_fn fn;
207 int n, has_phdr;
208
209 if (dso != NULL) {
210 has_phdr = _rtld_addr_phdr(dso, &phdr_info);
211 } else {
212 has_phdr = 0;
213 global_exit = 1;
214 }
215
216 _MUTEX_LOCK(&atexit_mutex);
217 current_finalize_dso = dso;
218 do {
219 call_finalize_again = false;
220 for (p = __atexit; p; p = p->next) {
221 for (n = p->ind; --n >= 0;) {
222 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
223 continue; /* already been called */
224 fn = p->fns[n];
225 if (dso != NULL && dso != fn.fn_dso) {
226 /* wrong DSO ? */
227 if (!has_phdr || global_exit ||
228 !__elf_phdr_match_addr(&phdr_info,
229 fn.fn_ptr.cxa_func))
230 continue;
231 }
232 /*
233 Mark entry to indicate that this particular
234 handler has already been called.
235 */
236 p->fns[n].fn_type = ATEXIT_FN_EMPTY;
237 _MUTEX_UNLOCK(&atexit_mutex);
238
239 /* Call the function of correct type. */
240 if (fn.fn_type == ATEXIT_FN_CXA)
241 fn.fn_ptr.cxa_func(fn.fn_arg);
242 else if (fn.fn_type == ATEXIT_FN_STD)
243 fn.fn_ptr.std_func();
244 _MUTEX_LOCK(&atexit_mutex);
245 }
246 }
247 } while (call_finalize_again);
248 current_finalize_dso = NULL;
249 _MUTEX_UNLOCK(&atexit_mutex);
250 if (dso == NULL)
251 _MUTEX_DESTROY(&atexit_mutex);
252
253 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL)
254 __pthread_cxa_finalize(&phdr_info);
255 }
256