1/* __cxa_atexit backwards-compatibility support for Darwin. 2 Copyright (C) 2006-2020 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 3, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16Under Section 7 of GPL version 3, you are granted additional 17permissions described in the GCC Runtime Library Exception, version 183.1, as published by the Free Software Foundation. 19 20You should have received a copy of the GNU General Public License and 21a copy of the GCC Runtime Library Exception along with this program; 22see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23<http://www.gnu.org/licenses/>. */ 24 25/* Don't do anything if we are compiling for a kext multilib. */ 26#ifdef __PIC__ 27 28#include "tconfig.h" 29#include "tsystem.h" 30 31#include <dlfcn.h> 32#include <stdbool.h> 33#include <stdlib.h> 34#include <string.h> 35 36/* This file works around two different problems. 37 38 The first problem is that there is no __cxa_atexit on Mac OS versions 39 before 10.4. It fixes this by providing a complete atexit and 40 __cxa_atexit emulation called from the regular atexit. 41 42 The second problem is that on all shipping versions of Mac OS, 43 __cxa_finalize and exit() don't work right: they don't run routines 44 that were registered while other atexit routines are running. This 45 is worked around by wrapping each atexit/__cxa_atexit routine with 46 our own routine which ensures that any __cxa_atexit calls while it 47 is running are honoured. 48 49 There are still problems which this does not solve. Before 10.4, 50 shared objects linked with previous compilers won't have their 51 atexit calls properly interleaved with code compiled with newer 52 compilers. Also, atexit routines registered from shared objects 53 linked with previous compilers won't get the bug fix. */ 54 55typedef int (*cxa_atexit_p)(void (*func) (void*), void* arg, const void* dso); 56typedef void (*cxa_finalize_p)(const void *dso); 57typedef int (*atexit_p)(void (*func)(void)); 58 59/* These are from "keymgr.h". */ 60extern void *_keymgr_get_and_lock_processwide_ptr (unsigned key); 61extern int _keymgr_get_and_lock_processwide_ptr_2 (unsigned, void **); 62extern int _keymgr_set_and_unlock_processwide_ptr (unsigned key, void *ptr); 63 64extern void *__keymgr_global[]; 65typedef struct _Sinfo_Node { 66 unsigned int size ; /*size of this node*/ 67 unsigned short major_version ; /*API major version.*/ 68 unsigned short minor_version ; /*API minor version.*/ 69 } _Tinfo_Node ; 70 71#ifdef __ppc__ 72#define CHECK_KEYMGR_ERROR(e) \ 73 (((_Tinfo_Node *)__keymgr_global[2])->major_version >= 4 ? (e) : 0) 74#else 75#define CHECK_KEYMGR_ERROR(e) (e) 76#endif 77 78/* Our globals are stored under this keymgr index. */ 79#define KEYMGR_ATEXIT_LIST 14 80 81/* The different kinds of callback routines. */ 82typedef void (*atexit_callback)(void); 83typedef void (*cxa_atexit_callback)(void *); 84 85/* This structure holds a routine to call. There may be extra fields 86 at the end of the structure that this code doesn't know about. */ 87struct one_atexit_routine 88{ 89 union { 90 atexit_callback ac; 91 cxa_atexit_callback cac; 92 } callback; 93 /* has_arg is 0/2/4 if 'ac' is live, 1/3/5 if 'cac' is live. 94 Higher numbers indicate a later version of the structure that this 95 code doesn't understand and will ignore. */ 96 int has_arg; 97 void * arg; 98}; 99 100struct atexit_routine_list 101{ 102 struct atexit_routine_list * next; 103 struct one_atexit_routine r; 104}; 105 106/* The various possibilities for status of atexit(). */ 107enum atexit_status { 108 atexit_status_unknown = 0, 109 atexit_status_missing = 1, 110 atexit_status_broken = 2, 111 atexit_status_working = 16 112}; 113 114struct keymgr_atexit_list 115{ 116 /* Version of this list. This code knows only about version 0. 117 If the version is higher than 0, this code may add new atexit routines 118 but should not attempt to run the list. */ 119 short version; 120 /* 1 if an atexit routine is currently being run by this code, 0 121 otherwise. */ 122 char running_routines; 123 /* Holds a value from 'enum atexit_status'. */ 124 unsigned char atexit_status; 125 /* The list of atexit and cxa_atexit routines registered. If 126 atexit_status_missing it contains all routines registered while 127 linked with this code. If atexit_status_broken it contains all 128 routines registered during cxa_finalize while linked with this 129 code. */ 130 struct atexit_routine_list *l; 131 /* &__cxa_atexit; set if atexit_status >= atexit_status_broken. */ 132 cxa_atexit_p cxa_atexit_f; 133 /* &__cxa_finalize; set if atexit_status >= atexit_status_broken. */ 134 cxa_finalize_p cxa_finalize_f; 135 /* &atexit; set if atexit_status >= atexit_status_working 136 or atexit_status == atexit_status_missing. */ 137 atexit_p atexit_f; 138}; 139 140/* Return 0 if __cxa_atexit has the bug it has in Mac OS 10.4: it 141 fails to call routines registered while an atexit routine is 142 running. Return 1 if it works properly, and -1 if an error occurred. */ 143 144struct atexit_data 145{ 146 int result; 147 cxa_atexit_p cxa_atexit; 148}; 149 150static void cxa_atexit_check_2 (void *arg) 151{ 152 ((struct atexit_data *)arg)->result = 1; 153} 154 155static void cxa_atexit_check_1 (void *arg) 156{ 157 struct atexit_data * aed = arg; 158 if (aed->cxa_atexit (cxa_atexit_check_2, arg, arg) != 0) 159 aed->result = -1; 160} 161 162static int 163check_cxa_atexit (cxa_atexit_p cxa_atexit, cxa_finalize_p cxa_finalize) 164{ 165 struct atexit_data aed = { 0, cxa_atexit }; 166 167 /* We re-use &aed as the 'dso' parameter, since it's a unique address. */ 168 if (cxa_atexit (cxa_atexit_check_1, &aed, &aed) != 0) 169 return -1; 170 cxa_finalize (&aed); 171 if (aed.result == 0) 172 { 173 /* Call __cxa_finalize again to make sure that cxa_atexit_check_2 174 is removed from the list before AED goes out of scope. */ 175 cxa_finalize (&aed); 176 aed.result = 0; 177 } 178 return aed.result; 179} 180 181#ifdef __ppc__ 182/* This comes from Csu. It works only before 10.4. The prototype has 183 been altered a bit to avoid casting. */ 184extern int _dyld_func_lookup(const char *dyld_func_name, 185 void *address) __attribute__((visibility("hidden"))); 186 187static void our_atexit (void); 188 189/* We're running on 10.3.9. Find the address of the system atexit() 190 function. So easy to say, so hard to do. */ 191static atexit_p 192find_atexit_10_3 (void) 193{ 194 unsigned int (*dyld_image_count_fn)(void); 195 const char *(*dyld_get_image_name_fn)(unsigned int image_index); 196 const void *(*dyld_get_image_header_fn)(unsigned int image_index); 197 const void *(*NSLookupSymbolInImage_fn)(const void *image, 198 const char *symbolName, 199 unsigned int options); 200 void *(*NSAddressOfSymbol_fn)(const void *symbol); 201 unsigned i, count; 202 203 /* Find some dyld functions. */ 204 _dyld_func_lookup("__dyld_image_count", &dyld_image_count_fn); 205 _dyld_func_lookup("__dyld_get_image_name", &dyld_get_image_name_fn); 206 _dyld_func_lookup("__dyld_get_image_header", &dyld_get_image_header_fn); 207 _dyld_func_lookup("__dyld_NSLookupSymbolInImage", &NSLookupSymbolInImage_fn); 208 _dyld_func_lookup("__dyld_NSAddressOfSymbol", &NSAddressOfSymbol_fn); 209 210 /* If any of these don't exist, that's an error. */ 211 if (! dyld_image_count_fn || ! dyld_get_image_name_fn 212 || ! dyld_get_image_header_fn || ! NSLookupSymbolInImage_fn 213 || ! NSAddressOfSymbol_fn) 214 return NULL; 215 216 count = dyld_image_count_fn (); 217 for (i = 0; i < count; i++) 218 { 219 const char * path = dyld_get_image_name_fn (i); 220 const void * image; 221 const void * symbol; 222 223 if (strcmp (path, "/usr/lib/libSystem.B.dylib") != 0) 224 continue; 225 image = dyld_get_image_header_fn (i); 226 if (! image) 227 return NULL; 228 /* '4' is NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR. */ 229 symbol = NSLookupSymbolInImage_fn (image, "_atexit", 4); 230 if (! symbol) 231 return NULL; 232 return NSAddressOfSymbol_fn (symbol); 233 } 234 return NULL; 235} 236#endif 237 238/* Create (if necessary), find, lock, fill in, and return our globals. 239 Return NULL on error, in which case the globals will not be locked. 240 The caller should call keymgr_set_and_unlock. */ 241static struct keymgr_atexit_list * 242get_globals (void) 243{ 244 struct keymgr_atexit_list * r; 245 246#ifdef __ppc__ 247 /* 10.3.9 doesn't have _keymgr_get_and_lock_processwide_ptr_2 so the 248 PPC side can't use it. On 10.4 this just means the error gets 249 reported a little later when 250 _keymgr_set_and_unlock_processwide_ptr finds that the key was 251 never locked. */ 252 r = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST); 253#else 254 void * rr; 255 if (_keymgr_get_and_lock_processwide_ptr_2 (KEYMGR_ATEXIT_LIST, &rr)) 256 return NULL; 257 r = rr; 258#endif 259 260 if (r == NULL) 261 { 262 r = calloc (sizeof (struct keymgr_atexit_list), 1); 263 if (! r) 264 return NULL; 265 } 266 267 if (r->atexit_status == atexit_status_unknown) 268 { 269 void *handle; 270 271 handle = dlopen ("/usr/lib/libSystem.B.dylib", RTLD_NOLOAD); 272 if (!handle) 273 { 274#ifdef __ppc__ 275 r->atexit_status = atexit_status_missing; 276 r->atexit_f = find_atexit_10_3 (); 277 if (! r->atexit_f) 278 goto error; 279 if (r->atexit_f (our_atexit)) 280 goto error; 281#else 282 goto error; 283#endif 284 } 285 else 286 { 287 int chk_result; 288 289 r->cxa_atexit_f = (cxa_atexit_p)dlsym (handle, "__cxa_atexit"); 290 r->cxa_finalize_f = (cxa_finalize_p)dlsym (handle, "__cxa_finalize"); 291 if (! r->cxa_atexit_f || ! r->cxa_finalize_f) 292 goto error; 293 294 chk_result = check_cxa_atexit (r->cxa_atexit_f, r->cxa_finalize_f); 295 if (chk_result == -1) 296 goto error; 297 else if (chk_result == 0) 298 r->atexit_status = atexit_status_broken; 299 else 300 { 301 r->atexit_f = (atexit_p)dlsym (handle, "atexit"); 302 if (! r->atexit_f) 303 goto error; 304 r->atexit_status = atexit_status_working; 305 } 306 } 307 } 308 309 return r; 310 311 error: 312 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, r); 313 return NULL; 314} 315 316/* Add TO_ADD to ATEXIT_LIST. ATEXIT_LIST may be NULL but is 317 always the result of calling _keymgr_get_and_lock_processwide_ptr and 318 so KEYMGR_ATEXIT_LIST is known to be locked; this routine is responsible 319 for unlocking it. */ 320 321static int 322add_routine (struct keymgr_atexit_list * g, 323 const struct one_atexit_routine * to_add) 324{ 325 struct atexit_routine_list * s 326 = malloc (sizeof (struct atexit_routine_list)); 327 int result; 328 329 if (!s) 330 { 331 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g); 332 return -1; 333 } 334 s->r = *to_add; 335 s->next = g->l; 336 g->l = s; 337 result = _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g); 338 return CHECK_KEYMGR_ERROR (result) == 0 ? 0 : -1; 339} 340 341/* This runs the routines in G->L up to STOP. */ 342static struct keymgr_atexit_list * 343run_routines (struct keymgr_atexit_list *g, 344 struct atexit_routine_list *stop) 345{ 346 for (;;) 347 { 348 struct atexit_routine_list * cur = g->l; 349 if (! cur || cur == stop) 350 break; 351 g->l = cur->next; 352 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g); 353 354 switch (cur->r.has_arg) { 355 case 0: case 2: case 4: 356 cur->r.callback.ac (); 357 break; 358 case 1: case 3: case 5: 359 cur->r.callback.cac (cur->r.arg); 360 break; 361 default: 362 /* Don't understand, so don't call it. */ 363 break; 364 } 365 free (cur); 366 367 g = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST); 368 if (! g) 369 break; 370 } 371 return g; 372} 373 374/* Call the routine described by ROUTINE_PARAM and then call any 375 routines added to KEYMGR_ATEXIT_LIST while that routine was 376 running, all with in_cxa_finalize set. */ 377 378static void 379cxa_atexit_wrapper (void* routine_param) 380{ 381 struct one_atexit_routine * routine = routine_param; 382 struct keymgr_atexit_list *g; 383 struct atexit_routine_list * base = NULL; 384 char prev_running = 0; 385 386 g = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST); 387 if (g) 388 { 389 prev_running = g->running_routines; 390 g->running_routines = 1; 391 base = g->l; 392 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g); 393 } 394 395 if (routine->has_arg) 396 routine->callback.cac (routine->arg); 397 else 398 routine->callback.ac (); 399 400 if (g) 401 g = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST); 402 if (g) 403 g = run_routines (g, base); 404 if (g) 405 { 406 g->running_routines = prev_running; 407 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g); 408 } 409} 410 411#ifdef __ppc__ 412/* This code is used while running on 10.3.9, when __cxa_atexit doesn't 413 exist in the system library. 10.3.9 only supported regular PowerPC, 414 so this code isn't necessary on x86 or ppc64. */ 415 416/* This routine is called from the system atexit(); it runs everything 417 registered on the KEYMGR_ATEXIT_LIST. */ 418 419static void 420our_atexit (void) 421{ 422 struct keymgr_atexit_list *g; 423 char prev_running; 424 425 g = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST); 426 if (! g || g->version != 0 || g->atexit_status != atexit_status_missing) 427 return; 428 429 prev_running = g->running_routines; 430 g->running_routines = 1; 431 g = run_routines (g, NULL); 432 if (! g) 433 return; 434 g->running_routines = prev_running; 435 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g); 436} 437#endif 438 439/* This is our wrapper around atexit and __cxa_atexit. It will return 440 nonzero if an error occurs, and otherwise: 441 - if in_cxa_finalize is set, or running on 10.3.9, add R to 442 KEYMGR_ATEXIT_LIST; or 443 - call the system __cxa_atexit to add cxa_atexit_wrapper with an argument 444 that indicates how cxa_atexit_wrapper should call R. */ 445 446static int 447atexit_common (const struct one_atexit_routine *r, const void *dso) 448{ 449 struct keymgr_atexit_list *g = get_globals (); 450 451 if (! g) 452 return -1; 453 454 if (g->running_routines || g->atexit_status == atexit_status_missing) 455 return add_routine (g, r); 456 457 if (g->atexit_status >= atexit_status_working) 458 { 459 int result; 460 if (r->has_arg) 461 { 462 cxa_atexit_p cxa_atexit = g->cxa_atexit_f; 463 result = _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, 464 g); 465 if (CHECK_KEYMGR_ERROR (result)) 466 return -1; 467 return cxa_atexit (r->callback.cac, r->arg, dso); 468 } 469 else 470 { 471 atexit_p atexit_f = g->atexit_f; 472 result = _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, 473 g); 474 if (CHECK_KEYMGR_ERROR (result)) 475 return -1; 476 return atexit_f (r->callback.ac); 477 } 478 } 479 else 480 { 481 cxa_atexit_p cxa_atexit = g->cxa_atexit_f; 482 struct one_atexit_routine *alloced; 483 int result; 484 485 result = _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g); 486 if (CHECK_KEYMGR_ERROR (result)) 487 return -1; 488 489 alloced = malloc (sizeof (struct one_atexit_routine)); 490 if (! alloced) 491 return -1; 492 *alloced = *r; 493 return cxa_atexit (cxa_atexit_wrapper, alloced, dso); 494 } 495} 496 497/* These are the actual replacement routines; they just funnel into 498 atexit_common. */ 499 500int __cxa_atexit (cxa_atexit_callback func, void* arg, 501 const void* dso) __attribute__((visibility("hidden"))); 502 503int 504__cxa_atexit (cxa_atexit_callback func, void* arg, const void* dso) 505{ 506 struct one_atexit_routine r; 507 r.callback.cac = func; 508 r.has_arg = 1; 509 r.arg = arg; 510 return atexit_common (&r, dso); 511} 512 513int atexit (atexit_callback func) __attribute__((visibility("hidden"))); 514 515/* Use __dso_handle to allow even bundles that call atexit() to be unloaded 516 on 10.4. */ 517extern void __dso_handle; 518 519int 520atexit (atexit_callback func) 521{ 522 struct one_atexit_routine r; 523 r.callback.ac = func; 524 r.has_arg = 0; 525 return atexit_common (&r, &__dso_handle); 526} 527 528#endif /* __PIC__ */ 529