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/*
* Copyright 2010-2011 PathScale, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdlib.h>
#include <dlfcn.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <pthread.h>
#include "typeinfo.h"
#include "dwarf_eh.h"
#include "cxxabi.h"
#pragma weak pthread_key_create
#pragma weak pthread_setspecific
#pragma weak pthread_getspecific
#pragma weak pthread_once
using namespace ABI_NAMESPACE;
/**
* Saves the result of the landing pad that we have found. For ARM, this is
* stored in the generic unwind structure, while on other platforms it is
* stored in the C++ exception.
*/
static void saveLandingPad(struct _Unwind_Context *context,
struct _Unwind_Exception *ucb,
struct __cxa_exception *ex,
int selector,
dw_eh_ptr_t landingPad)
{
#ifdef __arm__
// On ARM, we store the saved exception in the generic part of the structure
ucb->barrier_cache.sp = _Unwind_GetGR(context, 13);
ucb->barrier_cache.bitpattern[1] = (uint32_t)selector;
ucb->barrier_cache.bitpattern[3] = (uint32_t)landingPad;
#endif
// Cache the results for the phase 2 unwind, if we found a handler
// and this is not a foreign exception.
if (ex)
{
ex->handlerSwitchValue = selector;
ex->catchTemp = landingPad;
}
}
/**
* Loads the saved landing pad. Returns 1 on success, 0 on failure.
*/
static int loadLandingPad(struct _Unwind_Context *context,
struct _Unwind_Exception *ucb,
struct __cxa_exception *ex,
unsigned long *selector,
dw_eh_ptr_t *landingPad)
{
#ifdef __arm__
*selector = ucb->barrier_cache.bitpattern[1];
*landingPad = (dw_eh_ptr_t)ucb->barrier_cache.bitpattern[3];
return 1;
#else
if (ex)
{
*selector = ex->handlerSwitchValue;
*landingPad = (dw_eh_ptr_t)ex->catchTemp;
return 0;
}
return 0;
#endif
}
static inline _Unwind_Reason_Code continueUnwinding(struct _Unwind_Exception *ex,
struct _Unwind_Context *context)
{
#ifdef __arm__
if (__gnu_unwind_frame(ex, context) != _URC_OK) { return _URC_FAILURE; }
#endif
return _URC_CONTINUE_UNWIND;
}
extern "C" void __cxa_free_exception(void *thrown_exception);
extern "C" void __cxa_free_dependent_exception(void *thrown_exception);
extern "C" void* __dynamic_cast(const void *sub,
const __class_type_info *src,
const __class_type_info *dst,
ptrdiff_t src2dst_offset);
/**
* The type of a handler that has been found.
*/
typedef enum
{
/** No handler. */
handler_none,
/**
* A cleanup - the exception will propagate through this frame, but code
* must be run when this happens.
*/
handler_cleanup,
/**
* A catch statement. The exception will not propagate past this frame
* (without an explicit rethrow).
*/
handler_catch
} handler_type;
/**
* Per-thread info required by the runtime. We store a single structure
* pointer in thread-local storage, because this tends to be a scarce resource
* and it's impolite to steal all of it and not leave any for the rest of the
* program.
*
* Instances of this structure are allocated lazily - at most one per thread -
* and are destroyed on thread termination.
*/
struct __cxa_thread_info
{
/** The termination handler for this thread. */
terminate_handler terminateHandler;
/** The unexpected exception handler for this thread. */
unexpected_handler unexpectedHandler;
/**
* The number of emergency buffers held by this thread. This is 0 in
* normal operation - the emergency buffers are only used when malloc()
* fails to return memory for allocating an exception. Threads are not
* permitted to hold more than 4 emergency buffers (as per recommendation
* in ABI spec [3.3.1]).
*/
int emergencyBuffersHeld;
/**
* The exception currently running in a cleanup.
*/
_Unwind_Exception *currentCleanup;
/**
* The public part of this structure, accessible from outside of this
* module.
*/
__cxa_eh_globals globals;
};
/**
* Dependent exception. This
*/
struct __cxa_dependent_exception
{
#if __LP64__
void *primaryException;
#endif
std::type_info *exceptionType;
void (*exceptionDestructor) (void *);
unexpected_handler unexpectedHandler;
terminate_handler terminateHandler;
__cxa_exception *nextException;
int handlerCount;
#ifdef __arm__
_Unwind_Exception *nextCleanup;
int cleanupCount;
#endif
int handlerSwitchValue;
const char *actionRecord;
const char *languageSpecificData;
void *catchTemp;
void *adjustedPtr;
#if !__LP64__
void *primaryException;
#endif
_Unwind_Exception unwindHeader;
};
namespace std
{
void unexpected();
class exception
{
public:
virtual ~exception() throw();
virtual const char* what() const throw();
};
}
extern "C" std::type_info *__cxa_current_exception_type();
/**
* Class of exceptions to distinguish between this and other exception types.
*
* The first four characters are the vendor ID. Currently, we use GNUC,
* because we aim for ABI-compatibility with the GNU implementation, and
* various checks may test for equality of the class, which is incorrect.
*/
static const uint64_t exception_class =
EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\0');
/**
* Class used for dependent exceptions.
*/
static const uint64_t dependent_exception_class =
EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\x01');
/**
* The low four bytes of the exception class, indicating that we conform to the
* Itanium C++ ABI. This is currently unused, but should be used in the future
* if we change our exception class, to allow this library and libsupc++ to be
* linked to the same executable and both to interoperate.
*/
static const uint32_t abi_exception_class =
GENERIC_EXCEPTION_CLASS('C', '+', '+', '\0');
static bool isCXXException(uint64_t cls)
{
return (cls == exception_class) || (cls == dependent_exception_class);
}
static bool isDependentException(uint64_t cls)
{
return cls == dependent_exception_class;
}
static __cxa_exception *exceptionFromPointer(void *ex)
{
return (__cxa_exception*)((char*)ex -
offsetof(struct __cxa_exception, unwindHeader));
}
static __cxa_exception *realExceptionFromException(__cxa_exception *ex)
{
if (!isDependentException(ex->unwindHeader.exception_class)) { return ex; }
return ((__cxa_exception*)(((__cxa_dependent_exception*)ex)->primaryException))-1;
}
namespace std
{
// Forward declaration of standard library terminate() function used to
// abort execution.
void terminate(void);
}
using namespace ABI_NAMESPACE;
/** The global termination handler. */
static terminate_handler terminateHandler = abort;
/** The global unexpected exception handler. */
static unexpected_handler unexpectedHandler = std::terminate;
/** Key used for thread-local data. */
static pthread_key_t eh_key;
/**
* Cleanup function, allowing foreign exception handlers to correctly destroy
* this exception if they catch it.
*/
static void exception_cleanup(_Unwind_Reason_Code reason,
struct _Unwind_Exception *ex)
{
__cxa_free_exception((void*)ex);
}
static void dependent_exception_cleanup(_Unwind_Reason_Code reason,
struct _Unwind_Exception *ex)
{
__cxa_free_dependent_exception((void*)ex);
}
/**
* Recursively walk a list of exceptions and delete them all in post-order.
*/
static void free_exception_list(__cxa_exception *ex)
{
if (0 != ex->nextException)
{
free_exception_list(ex->nextException);
}
// __cxa_free_exception() expects to be passed the thrown object, which
// immediately follows the exception, not the exception itself
__cxa_free_exception(ex+1);
}
/**
* Cleanup function called when a thread exists to make certain that all of the
* per-thread data is deleted.
*/
static void thread_cleanup(void* thread_info)
{
__cxa_thread_info *info = (__cxa_thread_info*)thread_info;
if (info->globals.caughtExceptions)
{
free_exception_list(info->globals.caughtExceptions);
}
free(thread_info);
}
/**
* Once control used to protect the key creation.
*/
static pthread_once_t once_control = PTHREAD_ONCE_INIT;
/**
* We may not be linked against a full pthread implementation. If we're not,
* then we need to fake the thread-local storage by storing 'thread-local'
* things in a global.
*/
static bool fakeTLS;
/**
* Thread-local storage for a single-threaded program.
*/
static __cxa_thread_info singleThreadInfo;
/**
* Initialise eh_key.
*/
static void init_key(void)
{
if ((0 == pthread_key_create) ||
(0 == pthread_setspecific) ||
(0 == pthread_getspecific))
{
fakeTLS = true;
return;
}
pthread_key_create(&eh_key, thread_cleanup);
pthread_setspecific(eh_key, (void*)0x42);
fakeTLS = (pthread_getspecific(eh_key) != (void*)0x42);
pthread_setspecific(eh_key, 0);
}
/**
* Returns the thread info structure, creating it if it is not already created.
*/
static __cxa_thread_info *thread_info()
{
if ((0 == pthread_once) || pthread_once(&once_control, init_key))
{
fakeTLS = true;
}
if (fakeTLS) { return &singleThreadInfo; }
__cxa_thread_info *info = (__cxa_thread_info*)pthread_getspecific(eh_key);
if (0 == info)
{
info = (__cxa_thread_info*)calloc(1, sizeof(__cxa_thread_info));
pthread_setspecific(eh_key, info);
}
return info;
}
/**
* Fast version of thread_info(). May fail if thread_info() is not called on
* this thread at least once already.
*/
static __cxa_thread_info *thread_info_fast()
{
if (fakeTLS) { return &singleThreadInfo; }
return (__cxa_thread_info*)pthread_getspecific(eh_key);
}
/**
* ABI function returning the __cxa_eh_globals structure.
*/
extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals(void)
{
return &(thread_info()->globals);
}
/**
* Version of __cxa_get_globals() assuming that __cxa_get_globals() has already
* been called at least once by this thread.
*/
extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals_fast(void)
{
return &(thread_info_fast()->globals);
}
/**
* An emergency allocation reserved for when malloc fails. This is treated as
* 16 buffers of 1KB each.
*/
static char emergency_buffer[16384];
/**
* Flag indicating whether each buffer is allocated.
*/
static bool buffer_allocated[16];
/**
* Lock used to protect emergency allocation.
*/
static pthread_mutex_t emergency_malloc_lock = PTHREAD_MUTEX_INITIALIZER;
/**
* Condition variable used to wait when two threads are both trying to use the
* emergency malloc() buffer at once.
*/
static pthread_cond_t emergency_malloc_wait = PTHREAD_COND_INITIALIZER;
/**
* Allocates size bytes from the emergency allocation mechanism, if possible.
* This function will fail if size is over 1KB or if this thread already has 4
* emergency buffers. If all emergency buffers are allocated, it will sleep
* until one becomes available.
*/
static char *emergency_malloc(size_t size)
{
if (size > 1024) { return 0; }
__cxa_thread_info *info = thread_info();
// Only 4 emergency buffers allowed per thread!
if (info->emergencyBuffersHeld > 3) { return 0; }
pthread_mutex_lock(&emergency_malloc_lock);
int buffer = -1;
while (buffer < 0)
{
// While we were sleeping on the lock, another thread might have free'd
// enough memory for us to use, so try the allocation again - no point
// using the emergency buffer if there is some real memory that we can
// use...
void *m = calloc(1, size);
if (0 != m)
{
pthread_mutex_unlock(&emergency_malloc_lock);
return (char*)m;
}
for (int i=0 ; i<16 ; i++)
{
if (!buffer_allocated[i])
{
buffer = i;
buffer_allocated[i] = true;
break;
}
}
// If there still isn't a buffer available, then sleep on the condition
// variable. This will be signalled when another thread releases one
// of the emergency buffers.
if (buffer < 0)
{
pthread_cond_wait(&emergency_malloc_wait, &emergency_malloc_lock);
}
}
pthread_mutex_unlock(&emergency_malloc_lock);
info->emergencyBuffersHeld++;
return emergency_buffer + (1024 * buffer);
}
/**
* Frees a buffer returned by emergency_malloc().
*
* Note: Neither this nor emergency_malloc() is particularly efficient. This
* should not matter, because neither will be called in normal operation - they
* are only used when the program runs out of memory, which should not happen
* often.
*/
static void emergency_malloc_free(char *ptr)
{
int buffer = -1;
// Find the buffer corresponding to this pointer.
for (int i=0 ; i<16 ; i++)
{
if (ptr == (void*)(emergency_buffer + (1024 * i)))
{
buffer = i;
break;
}
}
assert(buffer > 0 &&
"Trying to free something that is not an emergency buffer!");
// emergency_malloc() is expected to return 0-initialized data. We don't
// zero the buffer when allocating it, because the static buffers will
// begin life containing 0 values.
memset((void*)ptr, 0, 1024);
// Signal the condition variable to wake up any threads that are blocking
// waiting for some space in the emergency buffer
pthread_mutex_lock(&emergency_malloc_lock);
// In theory, we don't need to do this with the lock held. In practice,
// our array of bools will probably be updated using 32-bit or 64-bit
// memory operations, so this update may clobber adjacent values.
buffer_allocated[buffer] = false;
pthread_cond_signal(&emergency_malloc_wait);
pthread_mutex_unlock(&emergency_malloc_lock);
}
static char *alloc_or_die(size_t size)
{
char *buffer = (char*)calloc(1, size);
// If calloc() doesn't want to give us any memory, try using an emergency
// buffer.
if (0 == buffer)
{
buffer = emergency_malloc(size);
// This is only reached if the allocation is greater than 1KB, and
// anyone throwing objects that big really should know better.
if (0 == buffer)
{
fprintf(stderr, "Out of memory attempting to allocate exception\n");
std::terminate();
}
}
return buffer;
}
static void free_exception(char *e)
{
// If this allocation is within the address range of the emergency buffer,
// don't call free() because it was not allocated with malloc()
if ((e > emergency_buffer) &&
(e < (emergency_buffer + sizeof(emergency_buffer))))
{
emergency_malloc_free(e);
}
else
{
free(e);
}
}
/**
* Allocates an exception structure. Returns a pointer to the space that can
* be used to store an object of thrown_size bytes. This function will use an
* emergency buffer if malloc() fails, and may block if there are no such
* buffers available.
*/
extern "C" void *__cxa_allocate_exception(size_t thrown_size)
{
size_t size = thrown_size + sizeof(__cxa_exception);
char *buffer = alloc_or_die(size);
return buffer+sizeof(__cxa_exception);
}
extern "C" void *__cxa_allocate_dependent_exception(void)
{
size_t size = sizeof(__cxa_dependent_exception);
char *buffer = alloc_or_die(size);
return buffer+sizeof(__cxa_dependent_exception);
}
/**
* __cxa_free_exception() is called when an exception was thrown in between
* calling __cxa_allocate_exception() and actually throwing the exception.
* This happens when the object's copy constructor throws an exception.
*
* In this implementation, it is also called by __cxa_end_catch() and during
* thread cleanup.
*/
extern "C" void __cxa_free_exception(void *thrown_exception)
{
__cxa_exception *ex = ((__cxa_exception*)thrown_exception) - 1;
// Free the object that was thrown, calling its destructor
if (0 != ex->exceptionDestructor)
{
try
{
ex->exceptionDestructor(thrown_exception);
}
catch(...)
{
// FIXME: Check that this is really what the spec says to do.
std::terminate();
}
}
free_exception((char*)ex);
}
static void releaseException(__cxa_exception *exception)
{
if (isDependentException(exception->unwindHeader.exception_class))
{
__cxa_free_dependent_exception(exception+1);
return;
}
if (__sync_sub_and_fetch(&exception->referenceCount, 1) == 0)
{
// __cxa_free_exception() expects to be passed the thrown object,
// which immediately follows the exception, not the exception
// itself
__cxa_free_exception(exception+1);
}
}
void __cxa_free_dependent_exception(void *thrown_exception)
{
__cxa_dependent_exception *ex = ((__cxa_dependent_exception*)thrown_exception) - 1;
assert(isDependentException(ex->unwindHeader.exception_class));
if (ex->primaryException)
{
releaseException(realExceptionFromException((__cxa_exception*)ex));
}
free_exception((char*)ex);
}
/**
* Callback function used with _Unwind_Backtrace().
*
* Prints a stack trace. Used only for debugging help.
*
* Note: As of FreeBSD 8.1, dladd() still doesn't work properly, so this only
* correctly prints function names from public, relocatable, symbols.
*/
static _Unwind_Reason_Code trace(struct _Unwind_Context *context, void *c)
{
Dl_info myinfo;
int mylookup =
dladdr((void*)(uintptr_t)__cxa_current_exception_type, &myinfo);
void *ip = (void*)_Unwind_GetIP(context);
Dl_info info;
if (dladdr(ip, &info) != 0)
{
if (mylookup == 0 || strcmp(info.dli_fname, myinfo.dli_fname) != 0)
{
printf("%p:%s() in %s\n", ip, info.dli_sname, info.dli_fname);
}
}
return _URC_CONTINUE_UNWIND;
}
/**
* Report a failure that occurred when attempting to throw an exception.
*
* If the failure happened by falling off the end of the stack without finding
* a handler, prints a back trace before aborting.
*/
static void report_failure(_Unwind_Reason_Code err, __cxa_exception *thrown_exception)
{
switch (err)
{
default: break;
case _URC_FATAL_PHASE1_ERROR:
fprintf(stderr, "Fatal error during phase 1 unwinding\n");
break;
#ifndef __arm__
case _URC_FATAL_PHASE2_ERROR:
fprintf(stderr, "Fatal error during phase 2 unwinding\n");
break;
#endif
case _URC_END_OF_STACK:
fprintf(stderr, "Terminating due to uncaught exception %p",
(void*)thrown_exception);
thrown_exception = realExceptionFromException(thrown_exception);
static const __class_type_info *e_ti =
static_cast<const __class_type_info*>(&typeid(std::exception));
const __class_type_info *throw_ti =
dynamic_cast<const __class_type_info*>(thrown_exception->exceptionType);
if (throw_ti)
{
std::exception *e =
(std::exception*)e_ti->cast_to((void*)(thrown_exception+1),
throw_ti);
if (e)
{
fprintf(stderr, " '%s'", e->what());
}
}
size_t bufferSize = 128;
char *demangled = (char*)malloc(bufferSize);
const char *mangled = thrown_exception->exceptionType->name();
int status;
demangled = __cxa_demangle(mangled, demangled, &bufferSize, &status);
fprintf(stderr, " of type %s\n",
status == 0 ? (const char*)demangled : mangled);
if (status == 0) { free(demangled); }
// Print a back trace if no handler is found.
// TODO: Make this optional
_Unwind_Backtrace(trace, 0);
break;
}
std::terminate();
}
static void throw_exception(__cxa_exception *ex)
{
__cxa_thread_info *info = thread_info();
ex->unexpectedHandler = info->unexpectedHandler;
if (0 == ex->unexpectedHandler)
{
ex->unexpectedHandler = unexpectedHandler;
}
ex->terminateHandler = info->terminateHandler;
if (0 == ex->terminateHandler)
{
ex->terminateHandler = terminateHandler;
}
info->globals.uncaughtExceptions++;
_Unwind_Reason_Code err = _Unwind_RaiseException(&ex->unwindHeader);
// The _Unwind_RaiseException() function should not return, it should
// unwind the stack past this function. If it does return, then something
// has gone wrong.
report_failure(err, ex);
}
/**
* ABI function for throwing an exception. Takes the object to be thrown (the
* pointer returned by __cxa_allocate_exception()), the type info for the
* pointee, and the destructor (if there is one) as arguments.
*/
extern "C" void __cxa_throw(void *thrown_exception,
std::type_info *tinfo,
void(*dest)(void*))
{
__cxa_exception *ex = ((__cxa_exception*)thrown_exception) - 1;
ex->referenceCount = 1;
ex->exceptionType = tinfo;
ex->exceptionDestructor = dest;
ex->unwindHeader.exception_class = exception_class;
ex->unwindHeader.exception_cleanup = exception_cleanup;
throw_exception(ex);
}
extern "C" void __cxa_rethrow_primary_exception(void* thrown_exception)
{
if (NULL == thrown_exception) { return; }
__cxa_exception *original = exceptionFromPointer(thrown_exception);
__cxa_dependent_exception *ex = ((__cxa_dependent_exception*)__cxa_allocate_dependent_exception())-1;
ex->primaryException = thrown_exception;
__cxa_increment_exception_refcount(thrown_exception);
ex->exceptionType = original->exceptionType;
ex->unwindHeader.exception_class = dependent_exception_class;
ex->unwindHeader.exception_cleanup = dependent_exception_cleanup;
throw_exception((__cxa_exception*)ex);
}
extern "C" void *__cxa_current_primary_exception(void)
{
__cxa_eh_globals* globals = __cxa_get_globals();
__cxa_exception *ex = globals->caughtExceptions;
if (0 == ex) { return NULL; }
ex = realExceptionFromException(ex);
__sync_fetch_and_add(&ex->referenceCount, 1);
return ex + 1;
}
extern "C" void __cxa_increment_exception_refcount(void* thrown_exception)
{
if (NULL == thrown_exception) { return; }
__cxa_exception *ex = ((__cxa_exception*)thrown_exception) - 1;
if (isDependentException(ex->unwindHeader.exception_class)) { return; }
__sync_fetch_and_add(&ex->referenceCount, 1);
}
extern "C" void __cxa_decrement_exception_refcount(void* thrown_exception)
{
if (NULL == thrown_exception) { return; }
__cxa_exception *ex = ((__cxa_exception*)thrown_exception) - 1;
releaseException(ex);
}
/**
* ABI function. Rethrows the current exception. Does not remove the
* exception from the stack or decrement its handler count - the compiler is
* expected to set the landing pad for this function to the end of the catch
* block, and then call _Unwind_Resume() to continue unwinding once
* __cxa_end_catch() has been called and any cleanup code has been run.
*/
extern "C" void __cxa_rethrow()
{
__cxa_eh_globals *globals = __cxa_get_globals();
// Note: We don't remove this from the caught list here, because
// __cxa_end_catch will be called when we unwind out of the try block. We
// could probably make this faster by providing an alternative rethrow
// function and ensuring that all cleanup code is run before calling it, so
// we can skip the top stack frame when unwinding.
__cxa_exception *ex = globals->caughtExceptions;
if (0 == ex)
{
fprintf(stderr,
"Attempting to rethrow an exception that doesn't exist!\n");
std::terminate();
}
assert(ex->handlerCount > 0 && "Rethrowing uncaught exception!");
// ex->handlerCount will be decremented in __cxa_end_catch in enclosing
// catch block
// Make handler count negative. This will tell __cxa_end_catch that
// exception was rethrown and exception object should not be destroyed
// when handler count become zero
ex->handlerCount = -ex->handlerCount;
// Continue unwinding the stack with this exception. This should unwind to
// the place in the caller where __cxa_end_catch() is called. The caller
// will then run cleanup code and bounce the exception back with
// _Unwind_Resume().
_Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(&ex->unwindHeader);
report_failure(err, ex);
}
/**
* Returns the type_info object corresponding to the filter.
*/
static std::type_info *get_type_info_entry(_Unwind_Context *context,
dwarf_eh_lsda *lsda,
int filter)
{
// Get the address of the record in the table.
dw_eh_ptr_t record = lsda->type_table -
dwarf_size_of_fixed_size_field(lsda->type_table_encoding)*filter;
//record -= 4;
dw_eh_ptr_t start = record;
// Read the value, but it's probably an indirect reference...
int64_t offset = read_value(lsda->type_table_encoding, &record);
// (If the entry is 0, don't try to dereference it. That would be bad.)
if (offset == 0) { return 0; }
// ...so we need to resolve it
return (std::type_info*)resolve_indirect_value(context,
lsda->type_table_encoding, offset, start);
}
/**
* Checks the type signature found in a handler against the type of the thrown
* object. If ex is 0 then it is assumed to be a foreign exception and only
* matches cleanups.
*/
static bool check_type_signature(__cxa_exception *ex,
const std::type_info *type,
void *&adjustedPtr)
{
void *exception_ptr = (void*)(ex+1);
const std::type_info *ex_type = ex->exceptionType;
bool is_ptr = ex_type->__is_pointer_p();
if (is_ptr)
{
exception_ptr = *(void**)exception_ptr;
}
// Always match a catchall, even with a foreign exception
//
// Note: A 0 here is a catchall, not a cleanup, so we return true to
// indicate that we found a catch.
if (0 == type)
{
if (ex)
{
adjustedPtr = exception_ptr;
}
return true;
}
if (0 == ex) { return false; }
// If the types are the same, no casting is needed.
if (*type == *ex_type)
{
adjustedPtr = exception_ptr;
return true;
}
if (type->__do_catch(ex_type, &exception_ptr, 1))
{
adjustedPtr = exception_ptr;
return true;
}
return false;
}
/**
* Checks whether the exception matches the type specifiers in this action
* record. If the exception only matches cleanups, then this returns false.
* If it matches a catch (including a catchall) then it returns true.
*
* The selector argument is used to return the selector that is passed in the
* second exception register when installing the context.
*/
static handler_type check_action_record(_Unwind_Context *context,
dwarf_eh_lsda *lsda,
dw_eh_ptr_t action_record,
__cxa_exception *ex,
unsigned long *selector,
void *&adjustedPtr)
{
if (!action_record) { return handler_cleanup; }
handler_type found = handler_none;
while (action_record)
{
int filter = read_sleb128(&action_record);
dw_eh_ptr_t action_record_offset_base = action_record;
int displacement = read_sleb128(&action_record);
action_record = displacement ?
action_record_offset_base + displacement : 0;
// We only check handler types for C++ exceptions - foreign exceptions
// are only allowed for cleanup.
if (filter > 0 && 0 != ex)
{
std::type_info *handler_type = get_type_info_entry(context, lsda, filter);
if (check_type_signature(ex, handler_type, adjustedPtr))
{
*selector = filter;
return handler_catch;
}
}
else if (filter < 0 && 0 != ex)
{
bool matched = false;
*selector = filter;
#ifdef __arm__
filter++;
std::type_info *handler_type = get_type_info_entry(context, lsda, filter--);
while (handler_type)
{
if (check_type_signature(ex, handler_type, adjustedPtr))
{
matched = true;
break;
}
handler_type = get_type_info_entry(context, lsda, filter--);
}
#else
unsigned char *type_index = ((unsigned char*)lsda->type_table - filter - 1);
while (*type_index)
{
std::type_info *handler_type = get_type_info_entry(context, lsda, *(type_index++));
// If the exception spec matches a permitted throw type for
// this function, don't report a handler - we are allowed to
// propagate this exception out.
if (check_type_signature(ex, handler_type, adjustedPtr))
{
matched = true;
break;
}
}
#endif
if (matched) { continue; }
// If we don't find an allowed exception spec, we need to install
// the context for this action. The landing pad will then call the
// unexpected exception function. Treat this as a catch
return handler_catch;
}
else if (filter == 0)
{
*selector = filter;
found = handler_cleanup;
}
}
return found;
}
static void pushCleanupException(_Unwind_Exception *exceptionObject,
__cxa_exception *ex)
{
#ifdef __arm__
__cxa_thread_info *info = thread_info_fast();
if (ex)
{
ex->cleanupCount++;
if (ex->cleanupCount > 1)
{
assert(exceptionObject == info->currentCleanup);
return;
}
ex->nextCleanup = info->currentCleanup;
}
info->currentCleanup = exceptionObject;
#endif
}
/**
* The exception personality function. This is referenced in the unwinding
* DWARF metadata and is called by the unwind library for each C++ stack frame
* containing catch or cleanup code.
*/
extern "C"
BEGIN_PERSONALITY_FUNCTION(__gxx_personality_v0)
// This personality function is for version 1 of the ABI. If you use it
// with a future version of the ABI, it won't know what to do, so it
// reports a fatal error and give up before it breaks anything.
if (1 != version)
{
return _URC_FATAL_PHASE1_ERROR;
}
__cxa_exception *ex = 0;
__cxa_exception *realEx = 0;
// If this exception is throw by something else then we can't make any
// assumptions about its layout beyond the fields declared in
// _Unwind_Exception.
bool foreignException = !isCXXException(exceptionClass);
// If this isn't a foreign exception, then we have a C++ exception structure
if (!foreignException)
{
ex = exceptionFromPointer(exceptionObject);
realEx = realExceptionFromException(ex);
}
unsigned char *lsda_addr =
(unsigned char*)_Unwind_GetLanguageSpecificData(context);
// No LSDA implies no landing pads - try the next frame
if (0 == lsda_addr) { return continueUnwinding(exceptionObject, context); }
// These two variables define how the exception will be handled.
dwarf_eh_action action = {0};
unsigned long selector = 0;
// During the search phase, we do a complete lookup. If we return
// _URC_HANDLER_FOUND, then the phase 2 unwind will call this function with
// a _UA_HANDLER_FRAME action, telling us to install the handler frame. If
// we return _URC_CONTINUE_UNWIND, we may be called again later with a
// _UA_CLEANUP_PHASE action for this frame.
//
// The point of the two-stage unwind allows us to entirely avoid any stack
// unwinding if there is no handler. If there are just cleanups found,
// then we can just panic call an abort function.
//
// Matching a handler is much more expensive than matching a cleanup,
// because we don't need to bother doing type comparisons (or looking at
// the type table at all) for a cleanup. This means that there is no need
// to cache the result of finding a cleanup, because it's (quite) quick to
// look it up again from the action table.
if (actions & _UA_SEARCH_PHASE)
{
struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
if (!dwarf_eh_find_callsite(context, &lsda, &action))
{
// EH range not found. This happens if exception is thrown and not
// caught inside a cleanup (destructor). We should call
// terminate() in this case. The catchTemp (landing pad) field of
// exception object will contain null when personality function is
// called with _UA_HANDLER_FRAME action for phase 2 unwinding.
return _URC_HANDLER_FOUND;
}
handler_type found_handler = check_action_record(context, &lsda,
action.action_record, realEx, &selector, ex->adjustedPtr);
// If there's no action record, we've only found a cleanup, so keep
// searching for something real
if (found_handler == handler_catch)
{
// Cache the results for the phase 2 unwind, if we found a handler
// and this is not a foreign exception.
if (ex)
{
saveLandingPad(context, exceptionObject, ex, selector, action.landing_pad);
ex->languageSpecificData = (const char*)lsda_addr;
ex->actionRecord = (const char*)action.action_record;
// ex->adjustedPtr is set when finding the action record.
}
return _URC_HANDLER_FOUND;
}
return continueUnwinding(exceptionObject, context);
}
// If this is a foreign exception, we didn't have anywhere to cache the
// lookup stuff, so we need to do it again. If this is either a forced
// unwind, a foreign exception, or a cleanup, then we just install the
// context for a cleanup.
if (!(actions & _UA_HANDLER_FRAME))
{
// cleanup
struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
dwarf_eh_find_callsite(context, &lsda, &action);
if (0 == action.landing_pad) { return continueUnwinding(exceptionObject, context); }
handler_type found_handler = check_action_record(context, &lsda,
action.action_record, realEx, &selector, ex->adjustedPtr);
// Ignore handlers this time.
if (found_handler != handler_cleanup) { return continueUnwinding(exceptionObject, context); }
pushCleanupException(exceptionObject, ex);
}
else if (foreignException)
{
struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
dwarf_eh_find_callsite(context, &lsda, &action);
check_action_record(context, &lsda, action.action_record, realEx,
&selector, ex->adjustedPtr);
}
else if (ex->catchTemp == 0)
{
// Uncaught exception in cleanup, calling terminate
std::terminate();
}
else
{
// Restore the saved info if we saved some last time.
loadLandingPad(context, exceptionObject, ex, &selector, &action.landing_pad);
ex->catchTemp = 0;
ex->handlerSwitchValue = 0;
}
_Unwind_SetIP(context, (unsigned long)action.landing_pad);
_Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
(unsigned long)exceptionObject);
_Unwind_SetGR(context, __builtin_eh_return_data_regno(1), selector);
return _URC_INSTALL_CONTEXT;
}
/**
* ABI function called when entering a catch statement. The argument is the
* pointer passed out of the personality function. This is always the start of
* the _Unwind_Exception object. The return value for this function is the
* pointer to the caught exception, which is either the adjusted pointer (for
* C++ exceptions) of the unadjusted pointer (for foreign exceptions).
*/
#if __GNUC__ > 3 && __GNUC_MINOR__ > 2
extern "C" void *__cxa_begin_catch(void *e) throw()
#else
extern "C" void *__cxa_begin_catch(void *e)
#endif
{
// Decrement the uncaught exceptions count
__cxa_eh_globals *globals = __cxa_get_globals();
globals->uncaughtExceptions--;
_Unwind_Exception *exceptionObject = (_Unwind_Exception*)e;
if (isCXXException(exceptionObject->exception_class))
{
__cxa_exception *ex = exceptionFromPointer(exceptionObject);
if (ex->handlerCount == 0)
{
// Add this to the front of the list of exceptions being handled
// and increment its handler count so that it won't be deleted
// prematurely.
ex->nextException = globals->caughtExceptions;
globals->caughtExceptions = ex;
}
if (ex->handlerCount < 0)
{
// Rethrown exception is catched before end of catch block.
// Clear the rethrow flag (make value positive) - we are allowed
// to delete this exception at the end of the catch block, as long
// as it isn't thrown again later.
// Code pattern:
//
// try {
// throw x;
// }
// catch() {
// try {
// throw;
// }
// catch() {
// __cxa_begin_catch() <- we are here
// }
// }
ex->handlerCount = -ex->handlerCount + 1;
}
else
{
ex->handlerCount++;
}
return ex->adjustedPtr;
}
// exceptionObject is the pointer to the _Unwind_Exception within the
// __cxa_exception. The throw object is after this
return ((char*)exceptionObject + sizeof(_Unwind_Exception));
}
/**
* ABI function called when exiting a catch block. This will free the current
* exception if it is no longer referenced in other catch blocks.
*/
extern "C" void __cxa_end_catch()
{
// We can call the fast version here because the slow version is called in
// __cxa_throw(), which must have been called before we end a catch block
__cxa_eh_globals *globals = __cxa_get_globals_fast();
__cxa_exception *ex = globals->caughtExceptions;
assert(0 != ex && "Ending catch when no exception is on the stack!");
bool deleteException = true;
if (ex->handlerCount < 0)
{
// exception was rethrown. Exception should not be deleted even if
// handlerCount become zero.
// Code pattern:
// try {
// throw x;
// }
// catch() {
// {
// throw;
// }
// cleanup {
// __cxa_end_catch(); <- we are here
// }
// }
//
ex->handlerCount++;
deleteException = false;
}
else
{
ex->handlerCount--;
}
if (ex->handlerCount == 0)
{
globals->caughtExceptions = ex->nextException;
if (deleteException)
{
releaseException(ex);
}
}
}
/**
* ABI function. Returns the type of the current exception.
*/
extern "C" std::type_info *__cxa_current_exception_type()
{
__cxa_eh_globals *globals = __cxa_get_globals();
__cxa_exception *ex = globals->caughtExceptions;
return ex ? ex->exceptionType : 0;
}
/**
* ABI function, called when an exception specification is violated.
*
* This function does not return.
*/
extern "C" void __cxa_call_unexpected(void*exception)
{
_Unwind_Exception *exceptionObject = (_Unwind_Exception*)exception;
if (exceptionObject->exception_class == exception_class)
{
__cxa_exception *ex = exceptionFromPointer(exceptionObject);
if (ex->unexpectedHandler)
{
ex->unexpectedHandler();
// Should not be reached.
abort();
}
}
std::unexpected();
// Should not be reached.
abort();
}
/**
* ABI function, returns the adjusted pointer to the exception object.
*/
extern "C" void *__cxa_get_exception_ptr(void *exceptionObject)
{
return exceptionFromPointer(exceptionObject)->adjustedPtr;
}
/**
* As an extension, we provide the ability for the unexpected and terminate
* handlers to be thread-local. We default to the standards-compliant
* behaviour where they are global.
*/
static bool thread_local_handlers = false;
namespace pathscale
{
/**
* Sets whether unexpected and terminate handlers should be thread-local.
*/
void set_use_thread_local_handlers(bool flag) throw()
{
thread_local_handlers = flag;
}
/**
* Sets a thread-local unexpected handler.
*/
unexpected_handler set_unexpected(unexpected_handler f) throw()
{
static __cxa_thread_info *info = thread_info();
unexpected_handler old = info->unexpectedHandler;
info->unexpectedHandler = f;
return old;
}
/**
* Sets a thread-local terminate handler.
*/
terminate_handler set_terminate(terminate_handler f) throw()
{
static __cxa_thread_info *info = thread_info();
terminate_handler old = info->terminateHandler;
info->terminateHandler = f;
return old;
}
}
namespace std
{
/**
* Sets the function that will be called when an exception specification is
* violated.
*/
unexpected_handler set_unexpected(unexpected_handler f) throw()
{
if (thread_local_handlers) { return pathscale::set_unexpected(f); }
return __sync_lock_test_and_set(&unexpectedHandler, f);
}
/**
* Sets the function that is called to terminate the program.
*/
terminate_handler set_terminate(terminate_handler f) throw()
{
if (thread_local_handlers) { return pathscale::set_terminate(f); }
return __sync_lock_test_and_set(&terminateHandler, f);
}
/**
* Terminates the program, calling a custom terminate implementation if
* required.
*/
void terminate()
{
static __cxa_thread_info *info = thread_info_fast();
if (0 != info && 0 != info->terminateHandler)
{
info->terminateHandler();
// Should not be reached - a terminate handler is not expected to
// return.
abort();
}
terminateHandler();
}
/**
* Called when an unexpected exception is encountered (i.e. an exception
* violates an exception specification). This calls abort() unless a
* custom handler has been set..
*/
void unexpected()
{
static __cxa_thread_info *info = thread_info_fast();
if (0 != info && 0 != info->unexpectedHandler)
{
info->unexpectedHandler();
// Should not be reached - a terminate handler is not expected to
// return.
abort();
}
unexpectedHandler();
}
/**
* Returns whether there are any exceptions currently being thrown that
* have not been caught. This can occur inside a nested catch statement.
*/
bool uncaught_exception() throw()
{
__cxa_thread_info *info = thread_info();
return info->globals.uncaughtExceptions != 0;
}
/**
* Returns the current unexpected handler.
*/
unexpected_handler get_unexpected() throw()
{
__cxa_thread_info *info = thread_info();
if (info->unexpectedHandler)
{
return info->unexpectedHandler;
}
return unexpectedHandler;
}
/**
* Returns the current terminate handler.
*/
terminate_handler get_terminate() throw()
{
__cxa_thread_info *info = thread_info();
if (info->terminateHandler)
{
return info->terminateHandler;
}
return terminateHandler;
}
}
#ifdef __arm__
extern "C" _Unwind_Exception *__cxa_get_cleanup(void)
{
__cxa_thread_info *info = thread_info_fast();
_Unwind_Exception *exceptionObject = info->currentCleanup;
if (isCXXException(exceptionObject->exception_class))
{
__cxa_exception *ex = exceptionFromPointer(exceptionObject);
ex->cleanupCount--;
if (ex->cleanupCount == 0)
{
info->currentCleanup = ex->nextCleanup;
ex->nextCleanup = 0;
}
}
else
{
info->currentCleanup = 0;
}
return exceptionObject;
}
asm (
".pushsection .text.__cxa_end_cleanup \n"
".global __cxa_end_cleanup \n"
".type __cxa_end_cleanup, \"function\" \n"
"__cxa_end_cleanup: \n"
" push {r1, r2, r3, r4} \n"
" bl __cxa_get_cleanup \n"
" push {r1, r2, r3, r4} \n"
" b _Unwind_Resume \n"
" bl abort \n"
".popsection \n"
);
#endif
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