external/bsd/libc++/dist/libcxxrt/src/cxxabi.h

   1 /*
   2  * Copyright 2012 David Chisnall. All rights reserved.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a copy
   5  * of this software and associated documentation files (the "Software"), to
   6  * deal in the Software without restriction, including without limitation the
   7  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
   8  * sell copies of the Software, and to permit persons to whom the Software is
   9  * furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be
  12  * included in all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  15  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  16  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  17  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  18  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  19  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  20  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  21  */
  22
  23 #ifndef __CXXABI_H_
  24 #define __CXXABI_H_
  25 #include <stdint.h>
  26 #include "unwind.h"
  27 namespace std
  28 {
  29         class type_info;
  30 }
  31 /*
  32  * The cxxabi.h header provides a set of public definitions for types and
  33  * functions defined by the Itanium C++ ABI specification.  For reference, see
  34  * the ABI specification here:
  35  *
  36  * http://sourcery.mentor.com/public/cxx-abi/abi.html
  37  *
  38  * All deviations from this specification, unless otherwise noted, are
  39  * accidental.
  40  */
  41
  42 #ifdef __cplusplus
  43 namespace __cxxabiv1 {
  44 extern "C" {
  45 #endif
  46 /**
  47  * Function type to call when an unexpected exception is encountered.
  48  */
  49 typedef void (*unexpected_handler)();
  50 /**
  51  * Function type to call when an unrecoverable condition is encountered.
  52  */
  53 typedef void (*terminate_handler)();
  54
  55
  56 /**
  57  * Structure used as a header on thrown exceptions.  This is the same layout as
  58  * defined by the Itanium ABI spec, so should be interoperable with any other
  59  * implementation of this spec, such as GNU libsupc++.
  60  *
  61  * This structure is allocated when an exception is thrown.  Unwinding happens
  62  * in two phases, the first looks for a handler and the second installs the
  63  * context.  This structure stores a cache of the handler location between
  64  * phase 1 and phase 2.  Unfortunately, cleanup information is not cached, so
  65  * must be looked up in both phases.  This happens for two reasons.  The first
  66  * is that we don't know how many frames containing cleanups there will be, and
  67  * we should avoid dynamic allocation during unwinding (the exception may be
  68  * reporting that we've run out of memory).  The second is that finding
  69  * cleanups is much cheaper than finding handlers, because we don't have to
  70  * look at the type table at all.
  71  *
  72  * Note: Several fields of this structure have not-very-informative names.
  73  * These are taken from the ABI spec and have not been changed to make it
  74  * easier for people referring to to the spec while reading this code.
  75  */
  76 struct __cxa_exception
  77 {
  78 #if __LP64__
  79         /**
  80          * Reference count.  Used to support the C++11 exception_ptr class.  This
  81          * is prepended to the structure in 64-bit mode and squeezed in to the
  82          * padding left before the 64-bit aligned _Unwind_Exception at the end in
  83          * 32-bit mode.
  84          *
  85          * Note that it is safe to extend this structure at the beginning, rather
  86          * than the end, because the public API for creating it returns the address
  87          * of the end (where the exception object can be stored).
  88          */
  89         uintptr_t referenceCount;
  90 #endif
  91         /** Type info for the thrown object. */
  92         std::type_info *exceptionType;
  93         /** Destructor for the object, if one exists. */
  94         void (*exceptionDestructor) (void *);
  95         /** Handler called when an exception specification is violated. */
  96         unexpected_handler unexpectedHandler;
  97         /** Hander called to terminate. */
  98         terminate_handler terminateHandler;
  99         /**
 100          * Next exception in the list.  If an exception is thrown inside a catch
 101          * block and caught in a nested catch, this points to the exception that
 102          * will be handled after the inner catch block completes.
 103          */
 104         __cxa_exception *nextException;
 105         /**
 106          * The number of handlers that currently have references to this
 107          * exception.  The top (non-sign) bit of this is used as a flag to indicate
 108          * that the exception is being rethrown, so should not be deleted when its
 109          * handler count reaches 0 (which it doesn't with the top bit set).
 110          */
 111         int handlerCount;
 112 #ifdef __arm__
 113         /**
 114          * The ARM EH ABI requires the unwind library to keep track of exceptions
 115          * during cleanups.  These support nesting, so we need to keep a list of
 116          * them.
 117          */
 118         _Unwind_Exception *nextCleanup;
 119         /**
 120          * The number of cleanups that are currently being run on this exception.
 121          */
 122         int cleanupCount;
 123 #endif
 124         /**
 125          * The selector value to be returned when installing the catch handler.
 126          * Used at the call site to determine which catch() block should execute.
 127          * This is found in phase 1 of unwinding then installed in phase 2.
 128          */
 129         int handlerSwitchValue;
 130         /**
 131          * The action record for the catch.  This is cached during phase 1
 132          * unwinding.
 133          */
 134         const char *actionRecord;
 135         /**
 136          * Pointer to the language-specific data area (LSDA) for the handler
 137          * frame.  This is unused in this implementation, but set for ABI
 138          * compatibility in case we want to mix code in very weird ways.
 139          */
 140         const char *languageSpecificData;
 141         /** The cached landing pad for the catch handler.*/
 142         void *catchTemp;
 143         /**
 144          * The pointer that will be returned as the pointer to the object.  When
 145          * throwing a class and catching a virtual superclass (for example), we
 146          * need to adjust the thrown pointer to make it all work correctly.
 147          */
 148         void *adjustedPtr;
 149 #if !__LP64__
 150         /**
 151          * Reference count.  Used to support the C++11 exception_ptr class.  This
 152          * is prepended to the structure in 64-bit mode and squeezed in to the
 153          * padding left before the 64-bit aligned _Unwind_Exception at the end in
 154          * 32-bit mode.
 155          *
 156          * Note that it is safe to extend this structure at the beginning, rather
 157          * than the end, because the public API for creating it returns the address
 158          * of the end (where the exception object can be stored)
 159          */
 160         uintptr_t referenceCount;
 161 #endif
 162         /** The language-agnostic part of the exception header. */
 163         _Unwind_Exception unwindHeader;
 164 };
 165
 166 /**
 167  * ABI-specified globals structure.  Returned by the __cxa_get_globals()
 168  * function and its fast variant.  This is a per-thread structure - every
 169  * thread will have one lazily allocated.
 170  *
 171  * This structure is defined by the ABI, so may be used outside of this
 172  * library.
 173  */
 174 struct __cxa_eh_globals
 175 {
 176         /**
 177          * A linked list of exceptions that are currently caught.  There may be
 178          * several of these in nested catch() blocks.
 179          */
 180         __cxa_exception *caughtExceptions;
 181         /**
 182          * The number of uncaught exceptions.
 183          */
 184         unsigned int uncaughtExceptions;
 185 };
 186 /**
 187  * ABI function returning the __cxa_eh_globals structure.
 188  */
 189 __cxa_eh_globals *__cxa_get_globals(void);
 190 /**
 191  * Version of __cxa_get_globals() assuming that __cxa_get_globals() has already
 192  * been called at least once by this thread.
 193  */
 194 __cxa_eh_globals *__cxa_get_globals_fast(void);
 195
 196 std::type_info * __cxa_current_exception_type();
 197
 198 /**
 199  * Throws an exception returned by __cxa_current_primary_exception().  This
 200  * exception may have been caught in another thread.
 201  */
 202 void __cxa_rethrow_primary_exception(void* thrown_exception);
 203 /**
 204  * Returns the current exception in a form that can be stored in an
 205  * exception_ptr object and then rethrown by a call to
 206  * __cxa_rethrow_primary_exception().
 207  */
 208 void *__cxa_current_primary_exception(void);
 209 /**
 210  * Increments the reference count of an exception.  Called when an
 211  * exception_ptr is copied.
 212  */
 213 void __cxa_increment_exception_refcount(void* thrown_exception);
 214 /**
 215  * Decrements the reference count of an exception.  Called when an
 216  * exception_ptr is deleted.
 217  */
 218 void __cxa_decrement_exception_refcount(void* thrown_exception);
 219 /**
 220  * Demangles a C++ symbol or type name.  The buffer, if non-NULL, must be
 221  * allocated with malloc() and must be *n bytes or more long.  This function
 222  * may call realloc() on the value pointed to by buf, and will return the
 223  * length of the string via *n.
 224  *
 225  * The value pointed to by status is set to one of the following:
 226  *
 227  * 0: success
 228  * -1: memory allocation failure
 229  * -2: invalid mangled name
 230  * -3: invalid arguments
 231  */
 232 char* __cxa_demangle(const char* mangled_name,
 233                      char* buf,
 234                      size_t* n,
 235                      int* status);
 236 #ifdef __cplusplus
 237 } // extern "C"
 238 } // namespace
 239
 240 namespace abi = __cxxabiv1;
 241
 242 #endif /* __cplusplus */
 243 #endif /* __CXXABI_H_ */