1 /* __cxa_atexit backwards-compatibility support for Darwin.
2 Copyright (C) 2006 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 2, or (at your option) any later
9 version.
10
11 In addition to the permissions in the GNU General Public License, the
12 Free Software Foundation gives you unlimited permission to link the
13 compiled version of this file into combinations with other programs,
14 and to distribute those combinations without any restriction coming
15 from the use of this file. (The General Public License restrictions
16 do apply in other respects; for example, they cover modification of
17 the file, and distribution when not linked into a combine
18 executable.)
19
20 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
21 WARRANTY; without even the implied warranty of MERCHANTABILITY or
22 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
23 for more details.
24
25 You should have received a copy of the GNU General Public License
26 along with GCC; see the file COPYING. If not, write to the Free
27 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
28 02110-1301, USA. */
29
30 /* Don't do anything if we are compiling for a kext multilib. */
31 #ifdef __PIC__
32
33 /* It is incorrect to include config.h here, because this file is being
34 compiled for the target, and hence definitions concerning only the host
35 do not apply. */
36
37 #include "tconfig.h"
38 #include "tsystem.h"
39
40 #include <dlfcn.h>
41 #include <stdbool.h>
42 #include <stdlib.h>
43 #include <string.h>
44
45 /* This file works around two different problems.
46
47 The first problem is that there is no __cxa_atexit on Mac OS versions
48 before 10.4. It fixes this by providing a complete atexit and
49 __cxa_atexit emulation called from the regular atexit.
50
51 The second problem is that on all shipping versions of Mac OS,
52 __cxa_finalize and exit() don't work right: they don't run routines
53 that were registered while other atexit routines are running. This
54 is worked around by wrapping each atexit/__cxa_atexit routine with
55 our own routine which ensures that any __cxa_atexit calls while it
56 is running are honoured.
57
58 There are still problems which this does not solve. Before 10.4,
59 shared objects linked with previous compilers won't have their
60 atexit calls properly interleaved with code compiled with newer
61 compilers. Also, atexit routines registered from shared objects
62 linked with previous compilers won't get the bug fix. */
63
64 typedef int (*cxa_atexit_p)(void (*func) (void*), void* arg, const void* dso);
65 typedef void (*cxa_finalize_p)(const void *dso);
66 typedef int (*atexit_p)(void (*func)(void));
67
68 /* These are from "keymgr.h". */
69 extern void *_keymgr_get_and_lock_processwide_ptr (unsigned key);
70 extern int _keymgr_get_and_lock_processwide_ptr_2 (unsigned, void **);
71 extern int _keymgr_set_and_unlock_processwide_ptr (unsigned key, void *ptr);
72
73 extern void *__keymgr_global[];
74 typedef struct _Sinfo_Node {
75 unsigned int size ; /*size of this node*/
76 unsigned short major_version ; /*API major version.*/
77 unsigned short minor_version ; /*API minor version.*/
78 } _Tinfo_Node ;
79
80 #ifdef __ppc__
81 #define CHECK_KEYMGR_ERROR(e) \
82 (((_Tinfo_Node *)__keymgr_global[2])->major_version >= 4 ? (e) : 0)
83 #else
84 #define CHECK_KEYMGR_ERROR(e) (e)
85 #endif
86
87 /* Our globals are stored under this keymgr index. */
88 #define KEYMGR_ATEXIT_LIST 14
89
90 /* The different kinds of callback routines. */
91 typedef void (*atexit_callback)(void);
92 typedef void (*cxa_atexit_callback)(void *);
93
94 /* This structure holds a routine to call. There may be extra fields
95 at the end of the structure that this code doesn't know about. */
96 struct one_atexit_routine
97 {
98 union {
99 atexit_callback ac;
100 cxa_atexit_callback cac;
101 } callback;
102 /* has_arg is 0/2/4 if 'ac' is live, 1/3/5 if 'cac' is live.
103 Higher numbers indicate a later version of the structure that this
104 code doesn't understand and will ignore. */
105 int has_arg;
106 void * arg;
107 };
108
109 struct atexit_routine_list
110 {
111 struct atexit_routine_list * next;
112 struct one_atexit_routine r;
113 };
114
115 /* The various possibilities for status of atexit(). */
116 enum atexit_status {
117 atexit_status_unknown = 0,
118 atexit_status_missing = 1,
119 atexit_status_broken = 2,
120 atexit_status_working = 16
121 };
122
123 struct keymgr_atexit_list
124 {
125 /* Version of this list. This code knows only about version 0.
126 If the version is higher than 0, this code may add new atexit routines
127 but should not attempt to run the list. */
128 short version;
129 /* 1 if an atexit routine is currently being run by this code, 0
130 otherwise. */
131 char running_routines;
132 /* Holds a value from 'enum atexit_status'. */
133 unsigned char atexit_status;
134 /* The list of atexit and cxa_atexit routines registered. If
135 atexit_status_missing it contains all routines registered while
136 linked with this code. If atexit_status_broken it contains all
137 routines registered during cxa_finalize while linked with this
138 code. */
139 struct atexit_routine_list *l;
140 /* &__cxa_atexit; set if atexit_status >= atexit_status_broken. */
141 cxa_atexit_p cxa_atexit_f;
142 /* &__cxa_finalize; set if atexit_status >= atexit_status_broken. */
143 cxa_finalize_p cxa_finalize_f;
144 /* &atexit; set if atexit_status >= atexit_status_working
145 or atexit_status == atexit_status_missing. */
146 atexit_p atexit_f;
147 };
148
149 /* Return 0 if __cxa_atexit has the bug it has in Mac OS 10.4: it
150 fails to call routines registered while an atexit routine is
151 running. Return 1 if it works properly, and -1 if an error occurred. */
152
153 struct atexit_data
154 {
155 int result;
156 cxa_atexit_p cxa_atexit;
157 };
158
cxa_atexit_check_2(void * arg)159 static void cxa_atexit_check_2 (void *arg)
160 {
161 ((struct atexit_data *)arg)->result = 1;
162 }
163
cxa_atexit_check_1(void * arg)164 static void cxa_atexit_check_1 (void *arg)
165 {
166 struct atexit_data * aed = arg;
167 if (aed->cxa_atexit (cxa_atexit_check_2, arg, arg) != 0)
168 aed->result = -1;
169 }
170
171 static int
check_cxa_atexit(cxa_atexit_p cxa_atexit,cxa_finalize_p cxa_finalize)172 check_cxa_atexit (cxa_atexit_p cxa_atexit, cxa_finalize_p cxa_finalize)
173 {
174 struct atexit_data aed = { 0, cxa_atexit };
175
176 /* We re-use &aed as the 'dso' parameter, since it's a unique address. */
177 if (cxa_atexit (cxa_atexit_check_1, &aed, &aed) != 0)
178 return -1;
179 cxa_finalize (&aed);
180 if (aed.result == 0)
181 {
182 /* Call __cxa_finalize again to make sure that cxa_atexit_check_2
183 is removed from the list before AED goes out of scope. */
184 cxa_finalize (&aed);
185 aed.result = 0;
186 }
187 return aed.result;
188 }
189
190 #ifdef __ppc__
191 /* This comes from Csu. It works only before 10.4. The prototype has
192 been altered a bit to avoid casting. */
193 extern int _dyld_func_lookup(const char *dyld_func_name,
194 void *address) __attribute__((visibility("hidden")));
195
196 static void our_atexit (void);
197
198 /* We're running on 10.3.9. Find the address of the system atexit()
199 function. So easy to say, so hard to do. */
200 static atexit_p
find_atexit_10_3(void)201 find_atexit_10_3 (void)
202 {
203 unsigned int (*dyld_image_count_fn)(void);
204 const char *(*dyld_get_image_name_fn)(unsigned int image_index);
205 const void *(*dyld_get_image_header_fn)(unsigned int image_index);
206 const void *(*NSLookupSymbolInImage_fn)(const void *image,
207 const char *symbolName,
208 unsigned int options);
209 void *(*NSAddressOfSymbol_fn)(const void *symbol);
210 unsigned i, count;
211
212 /* Find some dyld functions. */
213 _dyld_func_lookup("__dyld_image_count", &dyld_image_count_fn);
214 _dyld_func_lookup("__dyld_get_image_name", &dyld_get_image_name_fn);
215 _dyld_func_lookup("__dyld_get_image_header", &dyld_get_image_header_fn);
216 _dyld_func_lookup("__dyld_NSLookupSymbolInImage", &NSLookupSymbolInImage_fn);
217 _dyld_func_lookup("__dyld_NSAddressOfSymbol", &NSAddressOfSymbol_fn);
218
219 /* If any of these don't exist, that's an error. */
220 if (! dyld_image_count_fn || ! dyld_get_image_name_fn
221 || ! dyld_get_image_header_fn || ! NSLookupSymbolInImage_fn
222 || ! NSAddressOfSymbol_fn)
223 return NULL;
224
225 count = dyld_image_count_fn ();
226 for (i = 0; i < count; i++)
227 {
228 const char * path = dyld_get_image_name_fn (i);
229 const void * image;
230 const void * symbol;
231
232 if (strcmp (path, "/usr/lib/libSystem.B.dylib") != 0)
233 continue;
234 image = dyld_get_image_header_fn (i);
235 if (! image)
236 return NULL;
237 /* '4' is NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR. */
238 symbol = NSLookupSymbolInImage_fn (image, "_atexit", 4);
239 if (! symbol)
240 return NULL;
241 return NSAddressOfSymbol_fn (symbol);
242 }
243 return NULL;
244 }
245 #endif
246
247 /* Create (if necessary), find, lock, fill in, and return our globals.
248 Return NULL on error, in which case the globals will not be locked.
249 The caller should call keymgr_set_and_unlock. */
250 static struct keymgr_atexit_list *
get_globals(void)251 get_globals (void)
252 {
253 struct keymgr_atexit_list * r;
254
255 #ifdef __ppc__
256 /* 10.3.9 doesn't have _keymgr_get_and_lock_processwide_ptr_2 so the
257 PPC side can't use it. On 10.4 this just means the error gets
258 reported a little later when
259 _keymgr_set_and_unlock_processwide_ptr finds that the key was
260 never locked. */
261 r = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST);
262 #else
263 void * rr;
264 if (_keymgr_get_and_lock_processwide_ptr_2 (KEYMGR_ATEXIT_LIST, &rr))
265 return NULL;
266 r = rr;
267 #endif
268
269 if (r == NULL)
270 {
271 r = calloc (sizeof (struct keymgr_atexit_list), 1);
272 if (! r)
273 return NULL;
274 }
275
276 if (r->atexit_status == atexit_status_unknown)
277 {
278 void *handle;
279
280 handle = dlopen ("/usr/lib/libSystem.B.dylib", RTLD_NOLOAD);
281 if (!handle)
282 {
283 #ifdef __ppc__
284 r->atexit_status = atexit_status_missing;
285 r->atexit_f = find_atexit_10_3 ();
286 if (! r->atexit_f)
287 goto error;
288 if (r->atexit_f (our_atexit))
289 goto error;
290 #else
291 goto error;
292 #endif
293 }
294 else
295 {
296 int chk_result;
297
298 r->cxa_atexit_f = (cxa_atexit_p)dlsym (handle, "__cxa_atexit");
299 r->cxa_finalize_f = (cxa_finalize_p)dlsym (handle, "__cxa_finalize");
300 if (! r->cxa_atexit_f || ! r->cxa_finalize_f)
301 goto error;
302
303 chk_result = check_cxa_atexit (r->cxa_atexit_f, r->cxa_finalize_f);
304 if (chk_result == -1)
305 goto error;
306 else if (chk_result == 0)
307 r->atexit_status = atexit_status_broken;
308 else
309 {
310 r->atexit_f = (atexit_p)dlsym (handle, "atexit");
311 if (! r->atexit_f)
312 goto error;
313 r->atexit_status = atexit_status_working;
314 }
315 }
316 }
317
318 return r;
319
320 error:
321 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, r);
322 return NULL;
323 }
324
325 /* Add TO_ADD to ATEXIT_LIST. ATEXIT_LIST may be NULL but is
326 always the result of calling _keymgr_get_and_lock_processwide_ptr and
327 so KEYMGR_ATEXIT_LIST is known to be locked; this routine is responsible
328 for unlocking it. */
329
330 static int
add_routine(struct keymgr_atexit_list * g,const struct one_atexit_routine * to_add)331 add_routine (struct keymgr_atexit_list * g,
332 const struct one_atexit_routine * to_add)
333 {
334 struct atexit_routine_list * s
335 = malloc (sizeof (struct atexit_routine_list));
336 int result;
337
338 if (!s)
339 {
340 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g);
341 return -1;
342 }
343 s->r = *to_add;
344 s->next = g->l;
345 g->l = s;
346 result = _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g);
347 return CHECK_KEYMGR_ERROR (result) == 0 ? 0 : -1;
348 }
349
350 /* This runs the routines in G->L up to STOP. */
351 static struct keymgr_atexit_list *
run_routines(struct keymgr_atexit_list * g,struct atexit_routine_list * stop)352 run_routines (struct keymgr_atexit_list *g,
353 struct atexit_routine_list *stop)
354 {
355 for (;;)
356 {
357 struct atexit_routine_list * cur = g->l;
358 if (! cur || cur == stop)
359 break;
360 g->l = cur->next;
361 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g);
362
363 switch (cur->r.has_arg) {
364 case 0: case 2: case 4:
365 cur->r.callback.ac ();
366 break;
367 case 1: case 3: case 5:
368 cur->r.callback.cac (cur->r.arg);
369 break;
370 default:
371 /* Don't understand, so don't call it. */
372 break;
373 }
374 free (cur);
375
376 g = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST);
377 if (! g)
378 break;
379 }
380 return g;
381 }
382
383 /* Call the routine described by ROUTINE_PARAM and then call any
384 routines added to KEYMGR_ATEXIT_LIST while that routine was
385 running, all with in_cxa_finalize set. */
386
387 static void
cxa_atexit_wrapper(void * routine_param)388 cxa_atexit_wrapper (void* routine_param)
389 {
390 struct one_atexit_routine * routine = routine_param;
391 struct keymgr_atexit_list *g;
392 struct atexit_routine_list * base = NULL;
393 char prev_running = 0;
394
395 g = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST);
396 if (g)
397 {
398 prev_running = g->running_routines;
399 g->running_routines = 1;
400 base = g->l;
401 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g);
402 }
403
404 if (routine->has_arg)
405 routine->callback.cac (routine->arg);
406 else
407 routine->callback.ac ();
408
409 if (g)
410 g = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST);
411 if (g)
412 g = run_routines (g, base);
413 if (g)
414 {
415 g->running_routines = prev_running;
416 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g);
417 }
418 }
419
420 #ifdef __ppc__
421 /* This code is used while running on 10.3.9, when __cxa_atexit doesn't
422 exist in the system library. 10.3.9 only supported regular PowerPC,
423 so this code isn't necessary on x86 or ppc64. */
424
425 /* This routine is called from the system atexit(); it runs everything
426 registered on the KEYMGR_ATEXIT_LIST. */
427
428 static void
our_atexit(void)429 our_atexit (void)
430 {
431 struct keymgr_atexit_list *g;
432 char prev_running;
433
434 g = _keymgr_get_and_lock_processwide_ptr (KEYMGR_ATEXIT_LIST);
435 if (! g || g->version != 0 || g->atexit_status != atexit_status_missing)
436 return;
437
438 prev_running = g->running_routines;
439 g->running_routines = 1;
440 g = run_routines (g, NULL);
441 if (! g)
442 return;
443 g->running_routines = prev_running;
444 _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g);
445 }
446 #endif
447
448 /* This is our wrapper around atexit and __cxa_atexit. It will return
449 nonzero if an error occurs, and otherwise:
450 - if in_cxa_finalize is set, or running on 10.3.9, add R to
451 KEYMGR_ATEXIT_LIST; or
452 - call the system __cxa_atexit to add cxa_atexit_wrapper with an argument
453 that indicates how cxa_atexit_wrapper should call R. */
454
455 static int
atexit_common(const struct one_atexit_routine * r,const void * dso)456 atexit_common (const struct one_atexit_routine *r, const void *dso)
457 {
458 struct keymgr_atexit_list *g = get_globals ();
459
460 if (! g)
461 return -1;
462
463 if (g->running_routines || g->atexit_status == atexit_status_missing)
464 return add_routine (g, r);
465
466 if (g->atexit_status >= atexit_status_working)
467 {
468 int result;
469 if (r->has_arg)
470 {
471 cxa_atexit_p cxa_atexit = g->cxa_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 cxa_atexit (r->callback.cac, r->arg, dso);
477 }
478 else
479 {
480 atexit_p atexit_f = g->atexit_f;
481 result = _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST,
482 g);
483 if (CHECK_KEYMGR_ERROR (result))
484 return -1;
485 return atexit_f (r->callback.ac);
486 }
487 }
488 else
489 {
490 cxa_atexit_p cxa_atexit = g->cxa_atexit_f;
491 struct one_atexit_routine *alloced;
492 int result;
493
494 result = _keymgr_set_and_unlock_processwide_ptr (KEYMGR_ATEXIT_LIST, g);
495 if (CHECK_KEYMGR_ERROR (result))
496 return -1;
497
498 alloced = malloc (sizeof (struct one_atexit_routine));
499 if (! alloced)
500 return -1;
501 *alloced = *r;
502 return cxa_atexit (cxa_atexit_wrapper, alloced, dso);
503 }
504 }
505
506 /* These are the actual replacement routines; they just funnel into
507 atexit_common. */
508
509 int __cxa_atexit (cxa_atexit_callback func, void* arg,
510 const void* dso) __attribute__((visibility("hidden")));
511
512 int
__cxa_atexit(cxa_atexit_callback func,void * arg,const void * dso)513 __cxa_atexit (cxa_atexit_callback func, void* arg, const void* dso)
514 {
515 struct one_atexit_routine r;
516 r.callback.cac = func;
517 r.has_arg = 1;
518 r.arg = arg;
519 return atexit_common (&r, dso);
520 }
521
522 int atexit (atexit_callback func) __attribute__((visibility("hidden")));
523
524 /* Use __dso_handle to allow even bundles that call atexit() to be unloaded
525 on 10.4. */
526 extern void __dso_handle;
527
528 int
atexit(atexit_callback func)529 atexit (atexit_callback func)
530 {
531 struct one_atexit_routine r;
532 r.callback.ac = func;
533 r.has_arg = 0;
534 return atexit_common (&r, &__dso_handle);
535 }
536
537 #endif /* __PIC__ */
538