1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)atexit.c 8.2 (Berkeley) 7/3/94"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include "namespace.h" 40 #include <errno.h> 41 #include <link.h> 42 #include <stddef.h> 43 #include <stdlib.h> 44 #include <unistd.h> 45 #include <pthread.h> 46 #include "atexit.h" 47 #include "un-namespace.h" 48 #include "block_abi.h" 49 50 #include "libc_private.h" 51 52 /** 53 * The _Block_copy() function is provided by the block runtime. 54 */ 55 __attribute__((weak)) void* 56 _Block_copy(void*); 57 58 #define ATEXIT_FN_EMPTY 0 59 #define ATEXIT_FN_STD 1 60 #define ATEXIT_FN_CXA 2 61 62 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER; 63 64 #define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x) 65 #define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x) 66 #define _MUTEX_DESTROY(x) if (__isthreaded) _pthread_mutex_destroy(x) 67 68 struct atexit { 69 struct atexit *next; /* next in list */ 70 int ind; /* next index in this table */ 71 struct atexit_fn { 72 int fn_type; /* ATEXIT_? from above */ 73 union { 74 void (*std_func)(void); 75 void (*cxa_func)(void *); 76 } fn_ptr; /* function pointer */ 77 void *fn_arg; /* argument for CXA callback */ 78 void *fn_dso; /* shared module handle */ 79 } fns[ATEXIT_SIZE]; /* the table itself */ 80 }; 81 82 static struct atexit *__atexit; /* points to head of LIFO stack */ 83 typedef DECLARE_BLOCK(void, atexit_block, void); 84 85 /* 86 * Register the function described by 'fptr' to be called at application 87 * exit or owning shared object unload time. This is a helper function 88 * for atexit and __cxa_atexit. 89 */ 90 static int 91 atexit_register(struct atexit_fn *fptr) 92 { 93 static struct atexit __atexit0; /* one guaranteed table */ 94 struct atexit *p; 95 96 _MUTEX_LOCK(&atexit_mutex); 97 if ((p = __atexit) == NULL) 98 __atexit = p = &__atexit0; 99 else while (p->ind >= ATEXIT_SIZE) { 100 struct atexit *old__atexit; 101 old__atexit = __atexit; 102 _MUTEX_UNLOCK(&atexit_mutex); 103 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL) 104 return (-1); 105 _MUTEX_LOCK(&atexit_mutex); 106 if (old__atexit != __atexit) { 107 /* Lost race, retry operation */ 108 _MUTEX_UNLOCK(&atexit_mutex); 109 free(p); 110 _MUTEX_LOCK(&atexit_mutex); 111 p = __atexit; 112 continue; 113 } 114 p->ind = 0; 115 p->next = __atexit; 116 __atexit = p; 117 } 118 p->fns[p->ind++] = *fptr; 119 _MUTEX_UNLOCK(&atexit_mutex); 120 return 0; 121 } 122 123 /* 124 * Register a function to be performed at exit. 125 */ 126 int 127 atexit(void (*func)(void)) 128 { 129 struct atexit_fn fn; 130 int error; 131 132 fn.fn_type = ATEXIT_FN_STD; 133 fn.fn_ptr.std_func = func; 134 fn.fn_arg = NULL; 135 fn.fn_dso = NULL; 136 137 error = atexit_register(&fn); 138 return (error); 139 } 140 141 /** 142 * Register a block to be performed at exit. 143 */ 144 int 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 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 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