xref: /freebsd/contrib/libcxxrt/exception.cc (revision 46c1105fbb6fbff6d6ccd0a18571342eb992d637)
1 /*
2  * Copyright 2010-2011 PathScale, Inc. All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are met:
6  *
7  * 1. Redistributions of source code must retain the above copyright notice,
8  *    this list of conditions and the following disclaimer.
9  *
10  * 2. Redistributions in binary form must reproduce the above copyright notice,
11  *    this list of conditions and the following disclaimer in the documentation
12  *    and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
15  * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
16  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
18  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
21  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
22  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
23  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
24  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include <stdlib.h>
28 #include <dlfcn.h>
29 #include <stdio.h>
30 #include <string.h>
31 #include <stdint.h>
32 #include <pthread.h>
33 #include "typeinfo.h"
34 #include "dwarf_eh.h"
35 #include "atomic.h"
36 #include "cxxabi.h"
37 
38 #pragma weak pthread_key_create
39 #pragma weak pthread_setspecific
40 #pragma weak pthread_getspecific
41 #pragma weak pthread_once
42 #ifdef LIBCXXRT_WEAK_LOCKS
43 #pragma weak pthread_mutex_lock
44 #define pthread_mutex_lock(mtx) do {\
45 	if (pthread_mutex_lock) pthread_mutex_lock(mtx);\
46 	} while(0)
47 #pragma weak pthread_mutex_unlock
48 #define pthread_mutex_unlock(mtx) do {\
49 	if (pthread_mutex_unlock) pthread_mutex_unlock(mtx);\
50 	} while(0)
51 #pragma weak pthread_cond_signal
52 #define pthread_cond_signal(cv) do {\
53 	if (pthread_cond_signal) pthread_cond_signal(cv);\
54 	} while(0)
55 #pragma weak pthread_cond_wait
56 #define pthread_cond_wait(cv, mtx) do {\
57 	if (pthread_cond_wait) pthread_cond_wait(cv, mtx);\
58 	} while(0)
59 #endif
60 
61 using namespace ABI_NAMESPACE;
62 
63 /**
64  * Saves the result of the landing pad that we have found.  For ARM, this is
65  * stored in the generic unwind structure, while on other platforms it is
66  * stored in the C++ exception.
67  */
68 static void saveLandingPad(struct _Unwind_Context *context,
69                            struct _Unwind_Exception *ucb,
70                            struct __cxa_exception *ex,
71                            int selector,
72                            dw_eh_ptr_t landingPad)
73 {
74 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
75 	// On ARM, we store the saved exception in the generic part of the structure
76 	ucb->barrier_cache.sp = _Unwind_GetGR(context, 13);
77 	ucb->barrier_cache.bitpattern[1] = static_cast<uint32_t>(selector);
78 	ucb->barrier_cache.bitpattern[3] = reinterpret_cast<uint32_t>(landingPad);
79 #endif
80 	// Cache the results for the phase 2 unwind, if we found a handler
81 	// and this is not a foreign exception.
82 	if (ex)
83 	{
84 		ex->handlerSwitchValue = selector;
85 		ex->catchTemp = landingPad;
86 	}
87 }
88 
89 /**
90  * Loads the saved landing pad.  Returns 1 on success, 0 on failure.
91  */
92 static int loadLandingPad(struct _Unwind_Context *context,
93                           struct _Unwind_Exception *ucb,
94                           struct __cxa_exception *ex,
95                           unsigned long *selector,
96                           dw_eh_ptr_t *landingPad)
97 {
98 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
99 	*selector = ucb->barrier_cache.bitpattern[1];
100 	*landingPad = reinterpret_cast<dw_eh_ptr_t>(ucb->barrier_cache.bitpattern[3]);
101 	return 1;
102 #else
103 	if (ex)
104 	{
105 		*selector = ex->handlerSwitchValue;
106 		*landingPad = reinterpret_cast<dw_eh_ptr_t>(ex->catchTemp);
107 		return 0;
108 	}
109 	return 0;
110 #endif
111 }
112 
113 static inline _Unwind_Reason_Code continueUnwinding(struct _Unwind_Exception *ex,
114                                                     struct _Unwind_Context *context)
115 {
116 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
117 	if (__gnu_unwind_frame(ex, context) != _URC_OK) { return _URC_FAILURE; }
118 #endif
119 	return _URC_CONTINUE_UNWIND;
120 }
121 
122 
123 extern "C" void __cxa_free_exception(void *thrown_exception);
124 extern "C" void __cxa_free_dependent_exception(void *thrown_exception);
125 extern "C" void* __dynamic_cast(const void *sub,
126                                 const __class_type_info *src,
127                                 const __class_type_info *dst,
128                                 ptrdiff_t src2dst_offset);
129 
130 /**
131  * The type of a handler that has been found.
132  */
133 typedef enum
134 {
135 	/** No handler. */
136 	handler_none,
137 	/**
138 	 * A cleanup - the exception will propagate through this frame, but code
139 	 * must be run when this happens.
140 	 */
141 	handler_cleanup,
142 	/**
143 	 * A catch statement.  The exception will not propagate past this frame
144 	 * (without an explicit rethrow).
145 	 */
146 	handler_catch
147 } handler_type;
148 
149 /**
150  * Per-thread info required by the runtime.  We store a single structure
151  * pointer in thread-local storage, because this tends to be a scarce resource
152  * and it's impolite to steal all of it and not leave any for the rest of the
153  * program.
154  *
155  * Instances of this structure are allocated lazily - at most one per thread -
156  * and are destroyed on thread termination.
157  */
158 struct __cxa_thread_info
159 {
160 	/** The termination handler for this thread. */
161 	terminate_handler terminateHandler;
162 	/** The unexpected exception handler for this thread. */
163 	unexpected_handler unexpectedHandler;
164 	/**
165 	 * The number of emergency buffers held by this thread.  This is 0 in
166 	 * normal operation - the emergency buffers are only used when malloc()
167 	 * fails to return memory for allocating an exception.  Threads are not
168 	 * permitted to hold more than 4 emergency buffers (as per recommendation
169 	 * in ABI spec [3.3.1]).
170 	 */
171 	int emergencyBuffersHeld;
172 	/**
173 	 * The exception currently running in a cleanup.
174 	 */
175 	_Unwind_Exception *currentCleanup;
176 	/**
177 	 * Our state with respect to foreign exceptions.  Usually none, set to
178 	 * caught if we have just caught an exception and rethrown if we are
179 	 * rethrowing it.
180 	 */
181 	enum
182 	{
183 		none,
184 		caught,
185 		rethrown
186 	} foreign_exception_state;
187 	/**
188 	 * The public part of this structure, accessible from outside of this
189 	 * module.
190 	 */
191 	__cxa_eh_globals globals;
192 };
193 /**
194  * Dependent exception.  This
195  */
196 struct __cxa_dependent_exception
197 {
198 #if __LP64__
199 	void *primaryException;
200 #endif
201 	std::type_info *exceptionType;
202 	void (*exceptionDestructor) (void *);
203 	unexpected_handler unexpectedHandler;
204 	terminate_handler terminateHandler;
205 	__cxa_exception *nextException;
206 	int handlerCount;
207 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
208 	_Unwind_Exception *nextCleanup;
209 	int cleanupCount;
210 #endif
211 	int handlerSwitchValue;
212 	const char *actionRecord;
213 	const char *languageSpecificData;
214 	void *catchTemp;
215 	void *adjustedPtr;
216 #if !__LP64__
217 	void *primaryException;
218 #endif
219 	_Unwind_Exception unwindHeader;
220 };
221 
222 
223 namespace std
224 {
225 	void unexpected();
226 	class exception
227 	{
228 		public:
229 			virtual ~exception() throw();
230 			virtual const char* what() const throw();
231 	};
232 
233 }
234 
235 /**
236  * Class of exceptions to distinguish between this and other exception types.
237  *
238  * The first four characters are the vendor ID.  Currently, we use GNUC,
239  * because we aim for ABI-compatibility with the GNU implementation, and
240  * various checks may test for equality of the class, which is incorrect.
241  */
242 static const uint64_t exception_class =
243 	EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\0');
244 /**
245  * Class used for dependent exceptions.
246  */
247 static const uint64_t dependent_exception_class =
248 	EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\x01');
249 /**
250  * The low four bytes of the exception class, indicating that we conform to the
251  * Itanium C++ ABI.  This is currently unused, but should be used in the future
252  * if we change our exception class, to allow this library and libsupc++ to be
253  * linked to the same executable and both to interoperate.
254  */
255 static const uint32_t abi_exception_class =
256 	GENERIC_EXCEPTION_CLASS('C', '+', '+', '\0');
257 
258 static bool isCXXException(uint64_t cls)
259 {
260 	return (cls == exception_class) || (cls == dependent_exception_class);
261 }
262 
263 static bool isDependentException(uint64_t cls)
264 {
265 	return cls == dependent_exception_class;
266 }
267 
268 static __cxa_exception *exceptionFromPointer(void *ex)
269 {
270 	return reinterpret_cast<__cxa_exception*>(static_cast<char*>(ex) -
271 			offsetof(struct __cxa_exception, unwindHeader));
272 }
273 static __cxa_exception *realExceptionFromException(__cxa_exception *ex)
274 {
275 	if (!isDependentException(ex->unwindHeader.exception_class)) { return ex; }
276 	return reinterpret_cast<__cxa_exception*>((reinterpret_cast<__cxa_dependent_exception*>(ex))->primaryException)-1;
277 }
278 
279 
280 namespace std
281 {
282 	// Forward declaration of standard library terminate() function used to
283 	// abort execution.
284 	void terminate(void);
285 }
286 
287 using namespace ABI_NAMESPACE;
288 
289 
290 
291 /** The global termination handler. */
292 static terminate_handler terminateHandler = abort;
293 /** The global unexpected exception handler. */
294 static unexpected_handler unexpectedHandler = std::terminate;
295 
296 /** Key used for thread-local data. */
297 static pthread_key_t eh_key;
298 
299 
300 /**
301  * Cleanup function, allowing foreign exception handlers to correctly destroy
302  * this exception if they catch it.
303  */
304 static void exception_cleanup(_Unwind_Reason_Code reason,
305                               struct _Unwind_Exception *ex)
306 {
307 	// Exception layout:
308 	// [__cxa_exception [_Unwind_Exception]] [exception object]
309 	//
310 	// __cxa_free_exception expects a pointer to the exception object
311 	__cxa_free_exception(static_cast<void*>(ex + 1));
312 }
313 static void dependent_exception_cleanup(_Unwind_Reason_Code reason,
314                               struct _Unwind_Exception *ex)
315 {
316 
317 	__cxa_free_dependent_exception(static_cast<void*>(ex + 1));
318 }
319 
320 /**
321  * Recursively walk a list of exceptions and delete them all in post-order.
322  */
323 static void free_exception_list(__cxa_exception *ex)
324 {
325 	if (0 != ex->nextException)
326 	{
327 		free_exception_list(ex->nextException);
328 	}
329 	// __cxa_free_exception() expects to be passed the thrown object, which
330 	// immediately follows the exception, not the exception itself
331 	__cxa_free_exception(ex+1);
332 }
333 
334 /**
335  * Cleanup function called when a thread exists to make certain that all of the
336  * per-thread data is deleted.
337  */
338 static void thread_cleanup(void* thread_info)
339 {
340 	__cxa_thread_info *info = static_cast<__cxa_thread_info*>(thread_info);
341 	if (info->globals.caughtExceptions)
342 	{
343 		// If this is a foreign exception, ask it to clean itself up.
344 		if (info->foreign_exception_state != __cxa_thread_info::none)
345 		{
346 			_Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(info->globals.caughtExceptions);
347 			if (e->exception_cleanup)
348 				e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e);
349 		}
350 		else
351 		{
352 			free_exception_list(info->globals.caughtExceptions);
353 		}
354 	}
355 	free(thread_info);
356 }
357 
358 
359 /**
360  * Once control used to protect the key creation.
361  */
362 static pthread_once_t once_control = PTHREAD_ONCE_INIT;
363 
364 /**
365  * We may not be linked against a full pthread implementation.  If we're not,
366  * then we need to fake the thread-local storage by storing 'thread-local'
367  * things in a global.
368  */
369 static bool fakeTLS;
370 /**
371  * Thread-local storage for a single-threaded program.
372  */
373 static __cxa_thread_info singleThreadInfo;
374 /**
375  * Initialise eh_key.
376  */
377 static void init_key(void)
378 {
379 	if ((0 == pthread_key_create) ||
380 	    (0 == pthread_setspecific) ||
381 	    (0 == pthread_getspecific))
382 	{
383 		fakeTLS = true;
384 		return;
385 	}
386 	pthread_key_create(&eh_key, thread_cleanup);
387 	pthread_setspecific(eh_key, reinterpret_cast<void *>(0x42));
388 	fakeTLS = (pthread_getspecific(eh_key) != reinterpret_cast<void *>(0x42));
389 	pthread_setspecific(eh_key, 0);
390 }
391 
392 /**
393  * Returns the thread info structure, creating it if it is not already created.
394  */
395 static __cxa_thread_info *thread_info()
396 {
397 	if ((0 == pthread_once) || pthread_once(&once_control, init_key))
398 	{
399 		fakeTLS = true;
400 	}
401 	if (fakeTLS) { return &singleThreadInfo; }
402 	__cxa_thread_info *info = static_cast<__cxa_thread_info*>(pthread_getspecific(eh_key));
403 	if (0 == info)
404 	{
405 		info = static_cast<__cxa_thread_info*>(calloc(1, sizeof(__cxa_thread_info)));
406 		pthread_setspecific(eh_key, info);
407 	}
408 	return info;
409 }
410 /**
411  * Fast version of thread_info().  May fail if thread_info() is not called on
412  * this thread at least once already.
413  */
414 static __cxa_thread_info *thread_info_fast()
415 {
416 	if (fakeTLS) { return &singleThreadInfo; }
417 	return static_cast<__cxa_thread_info*>(pthread_getspecific(eh_key));
418 }
419 /**
420  * ABI function returning the __cxa_eh_globals structure.
421  */
422 extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals(void)
423 {
424 	return &(thread_info()->globals);
425 }
426 /**
427  * Version of __cxa_get_globals() assuming that __cxa_get_globals() has already
428  * been called at least once by this thread.
429  */
430 extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals_fast(void)
431 {
432 	return &(thread_info_fast()->globals);
433 }
434 
435 /**
436  * An emergency allocation reserved for when malloc fails.  This is treated as
437  * 16 buffers of 1KB each.
438  */
439 static char emergency_buffer[16384];
440 /**
441  * Flag indicating whether each buffer is allocated.
442  */
443 static bool buffer_allocated[16];
444 /**
445  * Lock used to protect emergency allocation.
446  */
447 static pthread_mutex_t emergency_malloc_lock = PTHREAD_MUTEX_INITIALIZER;
448 /**
449  * Condition variable used to wait when two threads are both trying to use the
450  * emergency malloc() buffer at once.
451  */
452 static pthread_cond_t emergency_malloc_wait = PTHREAD_COND_INITIALIZER;
453 
454 /**
455  * Allocates size bytes from the emergency allocation mechanism, if possible.
456  * This function will fail if size is over 1KB or if this thread already has 4
457  * emergency buffers.  If all emergency buffers are allocated, it will sleep
458  * until one becomes available.
459  */
460 static char *emergency_malloc(size_t size)
461 {
462 	if (size > 1024) { return 0; }
463 
464 	__cxa_thread_info *info = thread_info();
465 	// Only 4 emergency buffers allowed per thread!
466 	if (info->emergencyBuffersHeld > 3) { return 0; }
467 
468 	pthread_mutex_lock(&emergency_malloc_lock);
469 	int buffer = -1;
470 	while (buffer < 0)
471 	{
472 		// While we were sleeping on the lock, another thread might have free'd
473 		// enough memory for us to use, so try the allocation again - no point
474 		// using the emergency buffer if there is some real memory that we can
475 		// use...
476 		void *m = calloc(1, size);
477 		if (0 != m)
478 		{
479 			pthread_mutex_unlock(&emergency_malloc_lock);
480 			return static_cast<char*>(m);
481 		}
482 		for (int i=0 ; i<16 ; i++)
483 		{
484 			if (!buffer_allocated[i])
485 			{
486 				buffer = i;
487 				buffer_allocated[i] = true;
488 				break;
489 			}
490 		}
491 		// If there still isn't a buffer available, then sleep on the condition
492 		// variable.  This will be signalled when another thread releases one
493 		// of the emergency buffers.
494 		if (buffer < 0)
495 		{
496 			pthread_cond_wait(&emergency_malloc_wait, &emergency_malloc_lock);
497 		}
498 	}
499 	pthread_mutex_unlock(&emergency_malloc_lock);
500 	info->emergencyBuffersHeld++;
501 	return emergency_buffer + (1024 * buffer);
502 }
503 
504 /**
505  * Frees a buffer returned by emergency_malloc().
506  *
507  * Note: Neither this nor emergency_malloc() is particularly efficient.  This
508  * should not matter, because neither will be called in normal operation - they
509  * are only used when the program runs out of memory, which should not happen
510  * often.
511  */
512 static void emergency_malloc_free(char *ptr)
513 {
514 	int buffer = -1;
515 	// Find the buffer corresponding to this pointer.
516 	for (int i=0 ; i<16 ; i++)
517 	{
518 		if (ptr == static_cast<void*>(emergency_buffer + (1024 * i)))
519 		{
520 			buffer = i;
521 			break;
522 		}
523 	}
524 	assert(buffer >= 0 &&
525 	       "Trying to free something that is not an emergency buffer!");
526 	// emergency_malloc() is expected to return 0-initialized data.  We don't
527 	// zero the buffer when allocating it, because the static buffers will
528 	// begin life containing 0 values.
529 	memset(ptr, 0, 1024);
530 	// Signal the condition variable to wake up any threads that are blocking
531 	// waiting for some space in the emergency buffer
532 	pthread_mutex_lock(&emergency_malloc_lock);
533 	// In theory, we don't need to do this with the lock held.  In practice,
534 	// our array of bools will probably be updated using 32-bit or 64-bit
535 	// memory operations, so this update may clobber adjacent values.
536 	buffer_allocated[buffer] = false;
537 	pthread_cond_signal(&emergency_malloc_wait);
538 	pthread_mutex_unlock(&emergency_malloc_lock);
539 }
540 
541 static char *alloc_or_die(size_t size)
542 {
543 	char *buffer = static_cast<char*>(calloc(1, size));
544 
545 	// If calloc() doesn't want to give us any memory, try using an emergency
546 	// buffer.
547 	if (0 == buffer)
548 	{
549 		buffer = emergency_malloc(size);
550 		// This is only reached if the allocation is greater than 1KB, and
551 		// anyone throwing objects that big really should know better.
552 		if (0 == buffer)
553 		{
554 			fprintf(stderr, "Out of memory attempting to allocate exception\n");
555 			std::terminate();
556 		}
557 	}
558 	return buffer;
559 }
560 static void free_exception(char *e)
561 {
562 	// If this allocation is within the address range of the emergency buffer,
563 	// don't call free() because it was not allocated with malloc()
564 	if ((e >= emergency_buffer) &&
565 	    (e < (emergency_buffer + sizeof(emergency_buffer))))
566 	{
567 		emergency_malloc_free(e);
568 	}
569 	else
570 	{
571 		free(e);
572 	}
573 }
574 
575 /**
576  * Allocates an exception structure.  Returns a pointer to the space that can
577  * be used to store an object of thrown_size bytes.  This function will use an
578  * emergency buffer if malloc() fails, and may block if there are no such
579  * buffers available.
580  */
581 extern "C" void *__cxa_allocate_exception(size_t thrown_size)
582 {
583 	size_t size = thrown_size + sizeof(__cxa_exception);
584 	char *buffer = alloc_or_die(size);
585 	return buffer+sizeof(__cxa_exception);
586 }
587 
588 extern "C" void *__cxa_allocate_dependent_exception(void)
589 {
590 	size_t size = sizeof(__cxa_dependent_exception);
591 	char *buffer = alloc_or_die(size);
592 	return buffer+sizeof(__cxa_dependent_exception);
593 }
594 
595 /**
596  * __cxa_free_exception() is called when an exception was thrown in between
597  * calling __cxa_allocate_exception() and actually throwing the exception.
598  * This happens when the object's copy constructor throws an exception.
599  *
600  * In this implementation, it is also called by __cxa_end_catch() and during
601  * thread cleanup.
602  */
603 extern "C" void __cxa_free_exception(void *thrown_exception)
604 {
605 	__cxa_exception *ex = reinterpret_cast<__cxa_exception*>(thrown_exception) - 1;
606 	// Free the object that was thrown, calling its destructor
607 	if (0 != ex->exceptionDestructor)
608 	{
609 		try
610 		{
611 			ex->exceptionDestructor(thrown_exception);
612 		}
613 		catch(...)
614 		{
615 			// FIXME: Check that this is really what the spec says to do.
616 			std::terminate();
617 		}
618 	}
619 
620 	free_exception(reinterpret_cast<char*>(ex));
621 }
622 
623 static void releaseException(__cxa_exception *exception)
624 {
625 	if (isDependentException(exception->unwindHeader.exception_class))
626 	{
627 		__cxa_free_dependent_exception(exception+1);
628 		return;
629 	}
630 	if (__sync_sub_and_fetch(&exception->referenceCount, 1) == 0)
631 	{
632 		// __cxa_free_exception() expects to be passed the thrown object,
633 		// which immediately follows the exception, not the exception
634 		// itself
635 		__cxa_free_exception(exception+1);
636 	}
637 }
638 
639 void __cxa_free_dependent_exception(void *thrown_exception)
640 {
641 	__cxa_dependent_exception *ex = reinterpret_cast<__cxa_dependent_exception*>(thrown_exception) - 1;
642 	assert(isDependentException(ex->unwindHeader.exception_class));
643 	if (ex->primaryException)
644 	{
645 		releaseException(realExceptionFromException(reinterpret_cast<__cxa_exception*>(ex)));
646 	}
647 	free_exception(reinterpret_cast<char*>(ex));
648 }
649 
650 /**
651  * Callback function used with _Unwind_Backtrace().
652  *
653  * Prints a stack trace.  Used only for debugging help.
654  *
655  * Note: As of FreeBSD 8.1, dladd() still doesn't work properly, so this only
656  * correctly prints function names from public, relocatable, symbols.
657  */
658 static _Unwind_Reason_Code trace(struct _Unwind_Context *context, void *c)
659 {
660 	Dl_info myinfo;
661 	int mylookup =
662 		dladdr(reinterpret_cast<void *>(__cxa_current_exception_type), &myinfo);
663 	void *ip = reinterpret_cast<void*>(_Unwind_GetIP(context));
664 	Dl_info info;
665 	if (dladdr(ip, &info) != 0)
666 	{
667 		if (mylookup == 0 || strcmp(info.dli_fname, myinfo.dli_fname) != 0)
668 		{
669 			printf("%p:%s() in %s\n", ip, info.dli_sname, info.dli_fname);
670 		}
671 	}
672 	return _URC_CONTINUE_UNWIND;
673 }
674 
675 /**
676  * Report a failure that occurred when attempting to throw an exception.
677  *
678  * If the failure happened by falling off the end of the stack without finding
679  * a handler, prints a back trace before aborting.
680  */
681 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
682 extern "C" void *__cxa_begin_catch(void *e) throw();
683 #else
684 extern "C" void *__cxa_begin_catch(void *e);
685 #endif
686 static void report_failure(_Unwind_Reason_Code err, __cxa_exception *thrown_exception)
687 {
688 	switch (err)
689 	{
690 		default: break;
691 		case _URC_FATAL_PHASE1_ERROR:
692 			fprintf(stderr, "Fatal error during phase 1 unwinding\n");
693 			break;
694 #if !defined(__arm__) || defined(__ARM_DWARF_EH__)
695 		case _URC_FATAL_PHASE2_ERROR:
696 			fprintf(stderr, "Fatal error during phase 2 unwinding\n");
697 			break;
698 #endif
699 		case _URC_END_OF_STACK:
700 			__cxa_begin_catch (&(thrown_exception->unwindHeader));
701  			std::terminate();
702 			fprintf(stderr, "Terminating due to uncaught exception %p",
703 					static_cast<void*>(thrown_exception));
704 			thrown_exception = realExceptionFromException(thrown_exception);
705 			static const __class_type_info *e_ti =
706 				static_cast<const __class_type_info*>(&typeid(std::exception));
707 			const __class_type_info *throw_ti =
708 				dynamic_cast<const __class_type_info*>(thrown_exception->exceptionType);
709 			if (throw_ti)
710 			{
711 				std::exception *e =
712 					static_cast<std::exception*>(e_ti->cast_to(static_cast<void*>(thrown_exception+1),
713 							throw_ti));
714 				if (e)
715 				{
716 					fprintf(stderr, " '%s'", e->what());
717 				}
718 			}
719 
720 			size_t bufferSize = 128;
721 			char *demangled = static_cast<char*>(malloc(bufferSize));
722 			const char *mangled = thrown_exception->exceptionType->name();
723 			int status;
724 			demangled = __cxa_demangle(mangled, demangled, &bufferSize, &status);
725 			fprintf(stderr, " of type %s\n",
726 				status == 0 ? demangled : mangled);
727 			if (status == 0) { free(demangled); }
728 			// Print a back trace if no handler is found.
729 			// TODO: Make this optional
730 #ifndef __arm__
731 			_Unwind_Backtrace(trace, 0);
732 #endif
733 
734 			// Just abort. No need to call std::terminate for the second time
735 			abort();
736 			break;
737 	}
738 	std::terminate();
739 }
740 
741 static void throw_exception(__cxa_exception *ex)
742 {
743 	__cxa_thread_info *info = thread_info();
744 	ex->unexpectedHandler = info->unexpectedHandler;
745 	if (0 == ex->unexpectedHandler)
746 	{
747 		ex->unexpectedHandler = unexpectedHandler;
748 	}
749 	ex->terminateHandler  = info->terminateHandler;
750 	if (0 == ex->terminateHandler)
751 	{
752 		ex->terminateHandler = terminateHandler;
753 	}
754 	info->globals.uncaughtExceptions++;
755 
756 	_Unwind_Reason_Code err = _Unwind_RaiseException(&ex->unwindHeader);
757 	// The _Unwind_RaiseException() function should not return, it should
758 	// unwind the stack past this function.  If it does return, then something
759 	// has gone wrong.
760 	report_failure(err, ex);
761 }
762 
763 
764 /**
765  * ABI function for throwing an exception.  Takes the object to be thrown (the
766  * pointer returned by __cxa_allocate_exception()), the type info for the
767  * pointee, and the destructor (if there is one) as arguments.
768  */
769 extern "C" void __cxa_throw(void *thrown_exception,
770                             std::type_info *tinfo,
771                             void(*dest)(void*))
772 {
773 	__cxa_exception *ex = reinterpret_cast<__cxa_exception*>(thrown_exception) - 1;
774 
775 	ex->referenceCount = 1;
776 	ex->exceptionType = tinfo;
777 
778 	ex->exceptionDestructor = dest;
779 
780 	ex->unwindHeader.exception_class = exception_class;
781 	ex->unwindHeader.exception_cleanup = exception_cleanup;
782 
783 	throw_exception(ex);
784 }
785 
786 extern "C" void __cxa_rethrow_primary_exception(void* thrown_exception)
787 {
788 	if (NULL == thrown_exception) { return; }
789 
790 	__cxa_exception *original = exceptionFromPointer(thrown_exception);
791 	__cxa_dependent_exception *ex = reinterpret_cast<__cxa_dependent_exception*>(__cxa_allocate_dependent_exception())-1;
792 
793 	ex->primaryException = thrown_exception;
794 	__cxa_increment_exception_refcount(thrown_exception);
795 
796 	ex->exceptionType = original->exceptionType;
797 	ex->unwindHeader.exception_class = dependent_exception_class;
798 	ex->unwindHeader.exception_cleanup = dependent_exception_cleanup;
799 
800 	throw_exception(reinterpret_cast<__cxa_exception*>(ex));
801 }
802 
803 extern "C" void *__cxa_current_primary_exception(void)
804 {
805 	__cxa_eh_globals* globals = __cxa_get_globals();
806 	__cxa_exception *ex = globals->caughtExceptions;
807 
808 	if (0 == ex) { return NULL; }
809 	ex = realExceptionFromException(ex);
810 	__sync_fetch_and_add(&ex->referenceCount, 1);
811 	return ex + 1;
812 }
813 
814 extern "C" void __cxa_increment_exception_refcount(void* thrown_exception)
815 {
816 	if (NULL == thrown_exception) { return; }
817 	__cxa_exception *ex = static_cast<__cxa_exception*>(thrown_exception) - 1;
818 	if (isDependentException(ex->unwindHeader.exception_class)) { return; }
819 	__sync_fetch_and_add(&ex->referenceCount, 1);
820 }
821 extern "C" void __cxa_decrement_exception_refcount(void* thrown_exception)
822 {
823 	if (NULL == thrown_exception) { return; }
824 	__cxa_exception *ex = static_cast<__cxa_exception*>(thrown_exception) - 1;
825 	releaseException(ex);
826 }
827 
828 /**
829  * ABI function.  Rethrows the current exception.  Does not remove the
830  * exception from the stack or decrement its handler count - the compiler is
831  * expected to set the landing pad for this function to the end of the catch
832  * block, and then call _Unwind_Resume() to continue unwinding once
833  * __cxa_end_catch() has been called and any cleanup code has been run.
834  */
835 extern "C" void __cxa_rethrow()
836 {
837 	__cxa_thread_info *ti = thread_info();
838 	__cxa_eh_globals *globals = &ti->globals;
839 	// Note: We don't remove this from the caught list here, because
840 	// __cxa_end_catch will be called when we unwind out of the try block.  We
841 	// could probably make this faster by providing an alternative rethrow
842 	// function and ensuring that all cleanup code is run before calling it, so
843 	// we can skip the top stack frame when unwinding.
844 	__cxa_exception *ex = globals->caughtExceptions;
845 
846 	if (0 == ex)
847 	{
848 		fprintf(stderr,
849 		        "Attempting to rethrow an exception that doesn't exist!\n");
850 		std::terminate();
851 	}
852 
853 	if (ti->foreign_exception_state != __cxa_thread_info::none)
854 	{
855 		ti->foreign_exception_state = __cxa_thread_info::rethrown;
856 		_Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(ex);
857 		_Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(e);
858 		report_failure(err, ex);
859 		return;
860 	}
861 
862 	assert(ex->handlerCount > 0 && "Rethrowing uncaught exception!");
863 
864 	// ex->handlerCount will be decremented in __cxa_end_catch in enclosing
865 	// catch block
866 
867 	// Make handler count negative. This will tell __cxa_end_catch that
868 	// exception was rethrown and exception object should not be destroyed
869 	// when handler count become zero
870 	ex->handlerCount = -ex->handlerCount;
871 
872 	// Continue unwinding the stack with this exception.  This should unwind to
873 	// the place in the caller where __cxa_end_catch() is called.  The caller
874 	// will then run cleanup code and bounce the exception back with
875 	// _Unwind_Resume().
876 	_Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(&ex->unwindHeader);
877 	report_failure(err, ex);
878 }
879 
880 /**
881  * Returns the type_info object corresponding to the filter.
882  */
883 static std::type_info *get_type_info_entry(_Unwind_Context *context,
884                                            dwarf_eh_lsda *lsda,
885                                            int filter)
886 {
887 	// Get the address of the record in the table.
888 	dw_eh_ptr_t record = lsda->type_table -
889 		dwarf_size_of_fixed_size_field(lsda->type_table_encoding)*filter;
890 	//record -= 4;
891 	dw_eh_ptr_t start = record;
892 	// Read the value, but it's probably an indirect reference...
893 	int64_t offset = read_value(lsda->type_table_encoding, &record);
894 
895 	// (If the entry is 0, don't try to dereference it.  That would be bad.)
896 	if (offset == 0) { return 0; }
897 
898 	// ...so we need to resolve it
899 	return reinterpret_cast<std::type_info*>(resolve_indirect_value(context,
900 			lsda->type_table_encoding, offset, start));
901 }
902 
903 
904 
905 /**
906  * Checks the type signature found in a handler against the type of the thrown
907  * object.  If ex is 0 then it is assumed to be a foreign exception and only
908  * matches cleanups.
909  */
910 static bool check_type_signature(__cxa_exception *ex,
911                                  const std::type_info *type,
912                                  void *&adjustedPtr)
913 {
914 	void *exception_ptr = static_cast<void*>(ex+1);
915 	const std::type_info *ex_type = ex ? ex->exceptionType : 0;
916 
917 	bool is_ptr = ex ? ex_type->__is_pointer_p() : false;
918 	if (is_ptr)
919 	{
920 		exception_ptr = *static_cast<void**>(exception_ptr);
921 	}
922 	// Always match a catchall, even with a foreign exception
923 	//
924 	// Note: A 0 here is a catchall, not a cleanup, so we return true to
925 	// indicate that we found a catch.
926 	if (0 == type)
927 	{
928 		if (ex)
929 		{
930 			adjustedPtr = exception_ptr;
931 		}
932 		return true;
933 	}
934 
935 	if (0 == ex) { return false; }
936 
937 	// If the types are the same, no casting is needed.
938 	if (*type == *ex_type)
939 	{
940 		adjustedPtr = exception_ptr;
941 		return true;
942 	}
943 
944 
945 	if (type->__do_catch(ex_type, &exception_ptr, 1))
946 	{
947 		adjustedPtr = exception_ptr;
948 		return true;
949 	}
950 
951 	return false;
952 }
953 /**
954  * Checks whether the exception matches the type specifiers in this action
955  * record.  If the exception only matches cleanups, then this returns false.
956  * If it matches a catch (including a catchall) then it returns true.
957  *
958  * The selector argument is used to return the selector that is passed in the
959  * second exception register when installing the context.
960  */
961 static handler_type check_action_record(_Unwind_Context *context,
962                                         dwarf_eh_lsda *lsda,
963                                         dw_eh_ptr_t action_record,
964                                         __cxa_exception *ex,
965                                         unsigned long *selector,
966                                         void *&adjustedPtr)
967 {
968 	if (!action_record) { return handler_cleanup; }
969 	handler_type found = handler_none;
970 	while (action_record)
971 	{
972 		int filter = read_sleb128(&action_record);
973 		dw_eh_ptr_t action_record_offset_base = action_record;
974 		int displacement = read_sleb128(&action_record);
975 		action_record = displacement ?
976 			action_record_offset_base + displacement : 0;
977 		// We only check handler types for C++ exceptions - foreign exceptions
978 		// are only allowed for cleanups and catchalls.
979 		if (filter > 0)
980 		{
981 			std::type_info *handler_type = get_type_info_entry(context, lsda, filter);
982 			if (check_type_signature(ex, handler_type, adjustedPtr))
983 			{
984 				*selector = filter;
985 				return handler_catch;
986 			}
987 		}
988 		else if (filter < 0 && 0 != ex)
989 		{
990 			bool matched = false;
991 			*selector = filter;
992 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
993 			filter++;
994 			std::type_info *handler_type = get_type_info_entry(context, lsda, filter--);
995 			while (handler_type)
996 			{
997 				if (check_type_signature(ex, handler_type, adjustedPtr))
998 				{
999 					matched = true;
1000 					break;
1001 				}
1002 				handler_type = get_type_info_entry(context, lsda, filter--);
1003 			}
1004 #else
1005 			unsigned char *type_index = reinterpret_cast<unsigned char*>(lsda->type_table) - filter - 1;
1006 			while (*type_index)
1007 			{
1008 				std::type_info *handler_type = get_type_info_entry(context, lsda, *(type_index++));
1009 				// If the exception spec matches a permitted throw type for
1010 				// this function, don't report a handler - we are allowed to
1011 				// propagate this exception out.
1012 				if (check_type_signature(ex, handler_type, adjustedPtr))
1013 				{
1014 					matched = true;
1015 					break;
1016 				}
1017 			}
1018 #endif
1019 			if (matched) { continue; }
1020 			// If we don't find an allowed exception spec, we need to install
1021 			// the context for this action.  The landing pad will then call the
1022 			// unexpected exception function.  Treat this as a catch
1023 			return handler_catch;
1024 		}
1025 		else if (filter == 0)
1026 		{
1027 			*selector = filter;
1028 			found = handler_cleanup;
1029 		}
1030 	}
1031 	return found;
1032 }
1033 
1034 static void pushCleanupException(_Unwind_Exception *exceptionObject,
1035                                  __cxa_exception *ex)
1036 {
1037 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1038 	__cxa_thread_info *info = thread_info_fast();
1039 	if (ex)
1040 	{
1041 		ex->cleanupCount++;
1042 		if (ex->cleanupCount > 1)
1043 		{
1044 			assert(exceptionObject == info->currentCleanup);
1045 			return;
1046 		}
1047 		ex->nextCleanup = info->currentCleanup;
1048 	}
1049 	info->currentCleanup = exceptionObject;
1050 #endif
1051 }
1052 
1053 /**
1054  * The exception personality function.  This is referenced in the unwinding
1055  * DWARF metadata and is called by the unwind library for each C++ stack frame
1056  * containing catch or cleanup code.
1057  */
1058 extern "C"
1059 BEGIN_PERSONALITY_FUNCTION(__gxx_personality_v0)
1060 	// This personality function is for version 1 of the ABI.  If you use it
1061 	// with a future version of the ABI, it won't know what to do, so it
1062 	// reports a fatal error and give up before it breaks anything.
1063 	if (1 != version)
1064 	{
1065 		return _URC_FATAL_PHASE1_ERROR;
1066 	}
1067 	__cxa_exception *ex = 0;
1068 	__cxa_exception *realEx = 0;
1069 
1070 	// If this exception is throw by something else then we can't make any
1071 	// assumptions about its layout beyond the fields declared in
1072 	// _Unwind_Exception.
1073 	bool foreignException = !isCXXException(exceptionClass);
1074 
1075 	// If this isn't a foreign exception, then we have a C++ exception structure
1076 	if (!foreignException)
1077 	{
1078 		ex = exceptionFromPointer(exceptionObject);
1079 		realEx = realExceptionFromException(ex);
1080 	}
1081 
1082 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1083 	unsigned char *lsda_addr =
1084 		static_cast<unsigned char*>(_Unwind_GetLanguageSpecificData(context));
1085 #else
1086 	unsigned char *lsda_addr =
1087 		reinterpret_cast<unsigned char*>(static_cast<uintptr_t>(_Unwind_GetLanguageSpecificData(context)));
1088 #endif
1089 
1090 	// No LSDA implies no landing pads - try the next frame
1091 	if (0 == lsda_addr) { return continueUnwinding(exceptionObject, context); }
1092 
1093 	// These two variables define how the exception will be handled.
1094 	dwarf_eh_action action = {0};
1095 	unsigned long selector = 0;
1096 
1097 	// During the search phase, we do a complete lookup.  If we return
1098 	// _URC_HANDLER_FOUND, then the phase 2 unwind will call this function with
1099 	// a _UA_HANDLER_FRAME action, telling us to install the handler frame.  If
1100 	// we return _URC_CONTINUE_UNWIND, we may be called again later with a
1101 	// _UA_CLEANUP_PHASE action for this frame.
1102 	//
1103 	// The point of the two-stage unwind allows us to entirely avoid any stack
1104 	// unwinding if there is no handler.  If there are just cleanups found,
1105 	// then we can just panic call an abort function.
1106 	//
1107 	// Matching a handler is much more expensive than matching a cleanup,
1108 	// because we don't need to bother doing type comparisons (or looking at
1109 	// the type table at all) for a cleanup.  This means that there is no need
1110 	// to cache the result of finding a cleanup, because it's (quite) quick to
1111 	// look it up again from the action table.
1112 	if (actions & _UA_SEARCH_PHASE)
1113 	{
1114 		struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1115 
1116 		if (!dwarf_eh_find_callsite(context, &lsda, &action))
1117 		{
1118 			// EH range not found. This happens if exception is thrown and not
1119 			// caught inside a cleanup (destructor).  We should call
1120 			// terminate() in this case.  The catchTemp (landing pad) field of
1121 			// exception object will contain null when personality function is
1122 			// called with _UA_HANDLER_FRAME action for phase 2 unwinding.
1123 			return _URC_HANDLER_FOUND;
1124 		}
1125 
1126 		handler_type found_handler = check_action_record(context, &lsda,
1127 				action.action_record, realEx, &selector, ex->adjustedPtr);
1128 		// If there's no action record, we've only found a cleanup, so keep
1129 		// searching for something real
1130 		if (found_handler == handler_catch)
1131 		{
1132 			// Cache the results for the phase 2 unwind, if we found a handler
1133 			// and this is not a foreign exception.
1134 			if (ex)
1135 			{
1136 				saveLandingPad(context, exceptionObject, ex, selector, action.landing_pad);
1137 				ex->languageSpecificData = reinterpret_cast<const char*>(lsda_addr);
1138 				ex->actionRecord = reinterpret_cast<const char*>(action.action_record);
1139 				// ex->adjustedPtr is set when finding the action record.
1140 			}
1141 			return _URC_HANDLER_FOUND;
1142 		}
1143 		return continueUnwinding(exceptionObject, context);
1144 	}
1145 
1146 
1147 	// If this is a foreign exception, we didn't have anywhere to cache the
1148 	// lookup stuff, so we need to do it again.  If this is either a forced
1149 	// unwind, a foreign exception, or a cleanup, then we just install the
1150 	// context for a cleanup.
1151 	if (!(actions & _UA_HANDLER_FRAME))
1152 	{
1153 		// cleanup
1154 		struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1155 		dwarf_eh_find_callsite(context, &lsda, &action);
1156 		if (0 == action.landing_pad) { return continueUnwinding(exceptionObject, context); }
1157 		handler_type found_handler = check_action_record(context, &lsda,
1158 				action.action_record, realEx, &selector, ex->adjustedPtr);
1159 		// Ignore handlers this time.
1160 		if (found_handler != handler_cleanup) { return continueUnwinding(exceptionObject, context); }
1161 		pushCleanupException(exceptionObject, ex);
1162 	}
1163 	else if (foreignException)
1164 	{
1165 		struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1166 		dwarf_eh_find_callsite(context, &lsda, &action);
1167 		check_action_record(context, &lsda, action.action_record, realEx,
1168 				&selector, ex->adjustedPtr);
1169 	}
1170 	else if (ex->catchTemp == 0)
1171 	{
1172 		// Uncaught exception in cleanup, calling terminate
1173 		std::terminate();
1174 	}
1175 	else
1176 	{
1177 		// Restore the saved info if we saved some last time.
1178 		loadLandingPad(context, exceptionObject, ex, &selector, &action.landing_pad);
1179 		ex->catchTemp = 0;
1180 		ex->handlerSwitchValue = 0;
1181 	}
1182 
1183 
1184 	_Unwind_SetIP(context, reinterpret_cast<unsigned long>(action.landing_pad));
1185 	_Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
1186 	              reinterpret_cast<unsigned long>(exceptionObject));
1187 	_Unwind_SetGR(context, __builtin_eh_return_data_regno(1), selector);
1188 
1189 	return _URC_INSTALL_CONTEXT;
1190 }
1191 
1192 /**
1193  * ABI function called when entering a catch statement.  The argument is the
1194  * pointer passed out of the personality function.  This is always the start of
1195  * the _Unwind_Exception object.  The return value for this function is the
1196  * pointer to the caught exception, which is either the adjusted pointer (for
1197  * C++ exceptions) of the unadjusted pointer (for foreign exceptions).
1198  */
1199 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
1200 extern "C" void *__cxa_begin_catch(void *e) throw()
1201 #else
1202 extern "C" void *__cxa_begin_catch(void *e)
1203 #endif
1204 {
1205 	// We can't call the fast version here, because if the first exception that
1206 	// we see is a foreign exception then we won't have called it yet.
1207 	__cxa_thread_info *ti = thread_info();
1208 	__cxa_eh_globals *globals = &ti->globals;
1209 	globals->uncaughtExceptions--;
1210 	_Unwind_Exception *exceptionObject = static_cast<_Unwind_Exception*>(e);
1211 
1212 	if (isCXXException(exceptionObject->exception_class))
1213 	{
1214 		__cxa_exception *ex =  exceptionFromPointer(exceptionObject);
1215 
1216 		if (ex->handlerCount == 0)
1217 		{
1218 			// Add this to the front of the list of exceptions being handled
1219 			// and increment its handler count so that it won't be deleted
1220 			// prematurely.
1221 			ex->nextException = globals->caughtExceptions;
1222 			globals->caughtExceptions = ex;
1223 		}
1224 
1225 		if (ex->handlerCount < 0)
1226 		{
1227 			// Rethrown exception is catched before end of catch block.
1228 			// Clear the rethrow flag (make value positive) - we are allowed
1229 			// to delete this exception at the end of the catch block, as long
1230 			// as it isn't thrown again later.
1231 
1232 			// Code pattern:
1233 			//
1234 			// try {
1235 			//     throw x;
1236 			// }
1237 			// catch() {
1238 			//     try {
1239 			//         throw;
1240 			//     }
1241 			//     catch() {
1242 			//         __cxa_begin_catch() <- we are here
1243 			//     }
1244 			// }
1245 			ex->handlerCount = -ex->handlerCount + 1;
1246 		}
1247 		else
1248 		{
1249 			ex->handlerCount++;
1250 		}
1251 		ti->foreign_exception_state = __cxa_thread_info::none;
1252 
1253 		return ex->adjustedPtr;
1254 	}
1255 	else
1256 	{
1257 		// If this is a foreign exception, then we need to be able to
1258 		// store it.  We can't chain foreign exceptions, so we give up
1259 		// if there are already some outstanding ones.
1260 		if (globals->caughtExceptions != 0)
1261 		{
1262 			std::terminate();
1263 		}
1264 		globals->caughtExceptions = reinterpret_cast<__cxa_exception*>(exceptionObject);
1265 		ti->foreign_exception_state = __cxa_thread_info::caught;
1266 	}
1267 	// exceptionObject is the pointer to the _Unwind_Exception within the
1268 	// __cxa_exception.  The throw object is after this
1269 	return (reinterpret_cast<char*>(exceptionObject) + sizeof(_Unwind_Exception));
1270 }
1271 
1272 
1273 
1274 /**
1275  * ABI function called when exiting a catch block.  This will free the current
1276  * exception if it is no longer referenced in other catch blocks.
1277  */
1278 extern "C" void __cxa_end_catch()
1279 {
1280 	// We can call the fast version here because the slow version is called in
1281 	// __cxa_throw(), which must have been called before we end a catch block
1282 	__cxa_thread_info *ti = thread_info_fast();
1283 	__cxa_eh_globals *globals = &ti->globals;
1284 	__cxa_exception *ex = globals->caughtExceptions;
1285 
1286 	assert(0 != ex && "Ending catch when no exception is on the stack!");
1287 
1288 	if (ti->foreign_exception_state != __cxa_thread_info::none)
1289 	{
1290 		if (ti->foreign_exception_state != __cxa_thread_info::rethrown)
1291 		{
1292 			_Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(ti->globals.caughtExceptions);
1293 			if (e->exception_cleanup)
1294 				e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e);
1295 		}
1296 		globals->caughtExceptions = 0;
1297 		ti->foreign_exception_state = __cxa_thread_info::none;
1298 		return;
1299 	}
1300 
1301 	bool deleteException = true;
1302 
1303 	if (ex->handlerCount < 0)
1304 	{
1305 		// exception was rethrown. Exception should not be deleted even if
1306 		// handlerCount become zero.
1307 		// Code pattern:
1308 		// try {
1309 		//     throw x;
1310 		// }
1311 		// catch() {
1312 		//     {
1313 		//         throw;
1314 		//     }
1315 		//     cleanup {
1316 		//         __cxa_end_catch();   <- we are here
1317 		//     }
1318 		// }
1319 		//
1320 
1321 		ex->handlerCount++;
1322 		deleteException = false;
1323 	}
1324 	else
1325 	{
1326 		ex->handlerCount--;
1327 	}
1328 
1329 	if (ex->handlerCount == 0)
1330 	{
1331 		globals->caughtExceptions = ex->nextException;
1332 		if (deleteException)
1333 		{
1334 			releaseException(ex);
1335 		}
1336 	}
1337 }
1338 
1339 /**
1340  * ABI function.  Returns the type of the current exception.
1341  */
1342 extern "C" std::type_info *__cxa_current_exception_type()
1343 {
1344 	__cxa_eh_globals *globals = __cxa_get_globals();
1345 	__cxa_exception *ex = globals->caughtExceptions;
1346 	return ex ? ex->exceptionType : 0;
1347 }
1348 
1349 /**
1350  * ABI function, called when an exception specification is violated.
1351  *
1352  * This function does not return.
1353  */
1354 extern "C" void __cxa_call_unexpected(void*exception)
1355 {
1356 	_Unwind_Exception *exceptionObject = static_cast<_Unwind_Exception*>(exception);
1357 	if (exceptionObject->exception_class == exception_class)
1358 	{
1359 		__cxa_exception *ex =  exceptionFromPointer(exceptionObject);
1360 		if (ex->unexpectedHandler)
1361 		{
1362 			ex->unexpectedHandler();
1363 			// Should not be reached.
1364 			abort();
1365 		}
1366 	}
1367 	std::unexpected();
1368 	// Should not be reached.
1369 	abort();
1370 }
1371 
1372 /**
1373  * ABI function, returns the adjusted pointer to the exception object.
1374  */
1375 extern "C" void *__cxa_get_exception_ptr(void *exceptionObject)
1376 {
1377 	return exceptionFromPointer(exceptionObject)->adjustedPtr;
1378 }
1379 
1380 /**
1381  * As an extension, we provide the ability for the unexpected and terminate
1382  * handlers to be thread-local.  We default to the standards-compliant
1383  * behaviour where they are global.
1384  */
1385 static bool thread_local_handlers = false;
1386 
1387 
1388 namespace pathscale
1389 {
1390 	/**
1391 	 * Sets whether unexpected and terminate handlers should be thread-local.
1392 	 */
1393 	void set_use_thread_local_handlers(bool flag) throw()
1394 	{
1395 		thread_local_handlers = flag;
1396 	}
1397 	/**
1398 	 * Sets a thread-local unexpected handler.
1399 	 */
1400 	unexpected_handler set_unexpected(unexpected_handler f) throw()
1401 	{
1402 		static __cxa_thread_info *info = thread_info();
1403 		unexpected_handler old = info->unexpectedHandler;
1404 		info->unexpectedHandler = f;
1405 		return old;
1406 	}
1407 	/**
1408 	 * Sets a thread-local terminate handler.
1409 	 */
1410 	terminate_handler set_terminate(terminate_handler f) throw()
1411 	{
1412 		static __cxa_thread_info *info = thread_info();
1413 		terminate_handler old = info->terminateHandler;
1414 		info->terminateHandler = f;
1415 		return old;
1416 	}
1417 }
1418 
1419 namespace std
1420 {
1421 	/**
1422 	 * Sets the function that will be called when an exception specification is
1423 	 * violated.
1424 	 */
1425 	unexpected_handler set_unexpected(unexpected_handler f) throw()
1426 	{
1427 		if (thread_local_handlers) { return pathscale::set_unexpected(f); }
1428 
1429 		return ATOMIC_SWAP(&unexpectedHandler, f);
1430 	}
1431 	/**
1432 	 * Sets the function that is called to terminate the program.
1433 	 */
1434 	terminate_handler set_terminate(terminate_handler f) throw()
1435 	{
1436 		if (thread_local_handlers) { return pathscale::set_terminate(f); }
1437 
1438 		return ATOMIC_SWAP(&terminateHandler, f);
1439 	}
1440 	/**
1441 	 * Terminates the program, calling a custom terminate implementation if
1442 	 * required.
1443 	 */
1444 	void terminate()
1445 	{
1446 		static __cxa_thread_info *info = thread_info();
1447 		if (0 != info && 0 != info->terminateHandler)
1448 		{
1449 			info->terminateHandler();
1450 			// Should not be reached - a terminate handler is not expected to
1451 			// return.
1452 			abort();
1453 		}
1454 		terminateHandler();
1455 	}
1456 	/**
1457 	 * Called when an unexpected exception is encountered (i.e. an exception
1458 	 * violates an exception specification).  This calls abort() unless a
1459 	 * custom handler has been set..
1460 	 */
1461 	void unexpected()
1462 	{
1463 		static __cxa_thread_info *info = thread_info();
1464 		if (0 != info && 0 != info->unexpectedHandler)
1465 		{
1466 			info->unexpectedHandler();
1467 			// Should not be reached - a terminate handler is not expected to
1468 			// return.
1469 			abort();
1470 		}
1471 		unexpectedHandler();
1472 	}
1473 	/**
1474 	 * Returns whether there are any exceptions currently being thrown that
1475 	 * have not been caught.  This can occur inside a nested catch statement.
1476 	 */
1477 	bool uncaught_exception() throw()
1478 	{
1479 		__cxa_thread_info *info = thread_info();
1480 		return info->globals.uncaughtExceptions != 0;
1481 	}
1482 	/**
1483 	 * Returns the number of exceptions currently being thrown that have not
1484 	 * been caught.  This can occur inside a nested catch statement.
1485 	 */
1486 	int uncaught_exceptions() throw()
1487 	{
1488 		__cxa_thread_info *info = thread_info();
1489 		return info->globals.uncaughtExceptions;
1490 	}
1491 	/**
1492 	 * Returns the current unexpected handler.
1493 	 */
1494 	unexpected_handler get_unexpected() throw()
1495 	{
1496 		__cxa_thread_info *info = thread_info();
1497 		if (info->unexpectedHandler)
1498 		{
1499 			return info->unexpectedHandler;
1500 		}
1501 		return ATOMIC_LOAD(&unexpectedHandler);
1502 	}
1503 	/**
1504 	 * Returns the current terminate handler.
1505 	 */
1506 	terminate_handler get_terminate() throw()
1507 	{
1508 		__cxa_thread_info *info = thread_info();
1509 		if (info->terminateHandler)
1510 		{
1511 			return info->terminateHandler;
1512 		}
1513 		return ATOMIC_LOAD(&terminateHandler);
1514 	}
1515 }
1516 #if defined(__arm__) && !defined(__ARM_DWARF_EH__)
1517 extern "C" _Unwind_Exception *__cxa_get_cleanup(void)
1518 {
1519 	__cxa_thread_info *info = thread_info_fast();
1520 	_Unwind_Exception *exceptionObject = info->currentCleanup;
1521 	if (isCXXException(exceptionObject->exception_class))
1522 	{
1523 		__cxa_exception *ex =  exceptionFromPointer(exceptionObject);
1524 		ex->cleanupCount--;
1525 		if (ex->cleanupCount == 0)
1526 		{
1527 			info->currentCleanup = ex->nextCleanup;
1528 			ex->nextCleanup = 0;
1529 		}
1530 	}
1531 	else
1532 	{
1533 		info->currentCleanup = 0;
1534 	}
1535 	return exceptionObject;
1536 }
1537 
1538 asm (
1539 ".pushsection .text.__cxa_end_cleanup    \n"
1540 ".global __cxa_end_cleanup               \n"
1541 ".type __cxa_end_cleanup, \"function\"   \n"
1542 "__cxa_end_cleanup:                      \n"
1543 "	push {r1, r2, r3, r4}                \n"
1544 "	bl __cxa_get_cleanup                 \n"
1545 "	push {r1, r2, r3, r4}                \n"
1546 "	b _Unwind_Resume                     \n"
1547 "	bl abort                             \n"
1548 ".popsection                             \n"
1549 );
1550 #endif
1551