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 <stddef.h>
39 #include <stdlib.h>
40 #include <unistd.h>
41 #include <pthread.h>
42 #include "atexit.h"
43 #include "un-namespace.h"
44 #include "block_abi.h"
45
46 #include "libc_private.h"
47
48 /**
49 * The _Block_copy() function is provided by the block runtime.
50 */
51 __attribute__((weak)) void*
52 _Block_copy(void*);
53
54 #define ATEXIT_FN_EMPTY 0
55 #define ATEXIT_FN_STD 1
56 #define ATEXIT_FN_CXA 2
57
58 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
59
60 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x)
61 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x)
62 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x)
63
64 struct atexit {
65 struct atexit *next; /* next in list */
66 int ind; /* next index in this table */
67 struct atexit_fn {
68 int fn_type; /* ATEXIT_? from above */
69 union {
70 void (*std_func)(void);
71 void (*cxa_func)(void *);
72 } fn_ptr; /* function pointer */
73 void *fn_arg; /* argument for CXA callback */
74 void *fn_dso; /* shared module handle */
75 } fns[ATEXIT_SIZE]; /* the table itself */
76 };
77
78 static struct atexit *__atexit; /* points to head of LIFO stack */
79 typedef DECLARE_BLOCK(void, atexit_block, void);
80
81 int atexit_b(atexit_block);
82 int __cxa_atexit(void (*)(void *), void *, void *);
83
84 /*
85 * Register the function described by 'fptr' to be called at application
86 * exit or owning shared object unload time. This is a helper function
87 * for atexit and __cxa_atexit.
88 */
89 static int
atexit_register(struct atexit_fn * fptr)90 atexit_register(struct atexit_fn *fptr)
91 {
92 static struct atexit __atexit0; /* one guaranteed table */
93 struct atexit *p;
94
95 _MUTEX_LOCK(&atexit_mutex);
96 if ((p = __atexit) == NULL)
97 __atexit = p = &__atexit0;
98 else while (p->ind >= ATEXIT_SIZE) {
99 struct atexit *old__atexit;
100 old__atexit = __atexit;
101 _MUTEX_UNLOCK(&atexit_mutex);
102 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
103 return (-1);
104 _MUTEX_LOCK(&atexit_mutex);
105 if (old__atexit != __atexit) {
106 /* Lost race, retry operation */
107 _MUTEX_UNLOCK(&atexit_mutex);
108 free(p);
109 _MUTEX_LOCK(&atexit_mutex);
110 p = __atexit;
111 continue;
112 }
113 p->ind = 0;
114 p->next = __atexit;
115 __atexit = p;
116 }
117 p->fns[p->ind++] = *fptr;
118 _MUTEX_UNLOCK(&atexit_mutex);
119 return 0;
120 }
121
122 /*
123 * Register a function to be performed at exit.
124 */
125 int
atexit(void (* func)(void))126 atexit(void (*func)(void))
127 {
128 struct atexit_fn fn;
129 int error;
130
131 fn.fn_type = ATEXIT_FN_STD;
132 fn.fn_ptr.std_func = func;
133 fn.fn_arg = NULL;
134 fn.fn_dso = NULL;
135
136 error = atexit_register(&fn);
137 return (error);
138 }
139 __weak_reference(atexit, __libc_atexit);
140
141 /**
142 * Register a block to be performed at exit.
143 */
144 int
atexit_b(atexit_block func)145 atexit_b(atexit_block func)
146 {
147 struct atexit_fn fn;
148 int error;
149 if (_Block_copy == 0) {
150 errno = ENOSYS;
151 return -1;
152 }
153 func = _Block_copy(func);
154
155 // Blocks are not C++ destructors, but they have the same signature (a
156 // single void* parameter), so we can pretend that they are.
157 fn.fn_type = ATEXIT_FN_CXA;
158 fn.fn_ptr.cxa_func = (void(*)(void*))GET_BLOCK_FUNCTION(func);
159 fn.fn_arg = func;
160 fn.fn_dso = NULL;
161
162 error = atexit_register(&fn);
163 return (error);
164 }
165
166 /*
167 * Register a function to be performed at exit or when an shared object
168 * with given dso handle is unloaded dynamically.
169 */
170 int
__cxa_atexit(void (* func)(void *),void * arg,void * dso)171 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
172 {
173 struct atexit_fn fn;
174 int error;
175
176 fn.fn_type = ATEXIT_FN_CXA;
177 fn.fn_ptr.cxa_func = func;
178 fn.fn_arg = arg;
179 fn.fn_dso = dso;
180
181 error = atexit_register(&fn);
182 return (error);
183 }
184
185 #pragma weak __pthread_cxa_finalize
186 void __pthread_cxa_finalize(const struct dl_phdr_info *);
187
188 static int global_exit;
189
190 /*
191 * Call all handlers registered with __cxa_atexit for the shared
192 * object owning 'dso'. Note: if 'dso' is NULL, then all remaining
193 * handlers are called.
194 */
195 void
__cxa_finalize(void * dso)196 __cxa_finalize(void *dso)
197 {
198 struct dl_phdr_info phdr_info;
199 struct atexit *p;
200 struct atexit_fn fn;
201 int n, has_phdr;
202
203 if (dso != NULL) {
204 has_phdr = _rtld_addr_phdr(dso, &phdr_info);
205 } else {
206 has_phdr = 0;
207 global_exit = 1;
208 }
209
210 _MUTEX_LOCK(&atexit_mutex);
211 for (p = __atexit; p; p = p->next) {
212 for (n = p->ind; --n >= 0;) {
213 if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
214 continue; /* already been called */
215 fn = p->fns[n];
216 if (dso != NULL && dso != fn.fn_dso) {
217 /* wrong DSO ? */
218 if (!has_phdr || global_exit ||
219 !__elf_phdr_match_addr(&phdr_info,
220 fn.fn_ptr.cxa_func))
221 continue;
222 }
223 /*
224 Mark entry to indicate that this particular handler
225 has already been called.
226 */
227 p->fns[n].fn_type = ATEXIT_FN_EMPTY;
228 _MUTEX_UNLOCK(&atexit_mutex);
229
230 /* Call the function of correct type. */
231 if (fn.fn_type == ATEXIT_FN_CXA)
232 fn.fn_ptr.cxa_func(fn.fn_arg);
233 else if (fn.fn_type == ATEXIT_FN_STD)
234 fn.fn_ptr.std_func();
235 _MUTEX_LOCK(&atexit_mutex);
236 }
237 }
238 _MUTEX_UNLOCK(&atexit_mutex);
239 if (dso == NULL)
240 _MUTEX_DESTROY(&atexit_mutex);
241
242 if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL)
243 __pthread_cxa_finalize(&phdr_info);
244 }
245