sources/cxx-stl/gabi++/src/cxxabi.cc

// Copyright (C) 2012 The Android Open Source Project
// 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.
// 3. Neither the name of the project nor the names of its contributors
//    may be used to endorse or promote products derived from this software
//    without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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 <cassert>
#include <cstdio>
#include <cstdlib>
#include <cxxabi.h>
#include <exception>
#include <pthread.h>

#include "helper_func_internal.h"

namespace {

  using namespace __cxxabiv1;

  bool isOurCxxException(uint64_t exc) {
    // Compatible with GNU
    return exc == __gxx_exception_class;
  }

  void defaultExceptionCleanupFunc(_Unwind_Reason_Code reason, _Unwind_Exception* exc) {
    __cxa_free_exception(exc);
  }

  // Technical note:
  // Use a pthread_key_t to hold the key used to store our thread-specific
  // __cxa_thread_info objects. The key is created and destroyed through
  // a static C++ object.
  //

  // Due to a bug in the dynamic linker that was only fixed in Froyo, the
  // static C++ destructor may be called with a value of NULL for the
  // 'this' pointer. As such, any attempt to access any field in the
  // object there will result in a crash. To work-around this, store
  // the key object as a 'static' variable outside of the C++ object.
  static pthread_key_t __cxa_thread_key;

  class CxaThreadKey {
  public:
    // Called at program initialization time, or when the shared library
    // is loaded through dlopen().
    CxaThreadKey() {
      if (pthread_key_create(&__cxa_thread_key, freeObject) != 0) {
        fatalError("Can't allocate C++ runtime pthread_key_t");
      }
    }

    // Called at program exit time, or when the shared library is
    // unloaded through dlclose(). See note above.
    ~CxaThreadKey() {
      pthread_key_delete(__cxa_thread_key);
    }

    static __cxa_thread_info* getFast() {
      void* obj = pthread_getspecific(__cxa_thread_key);
      return reinterpret_cast<__cxa_thread_info*>(obj);
    }

    static __cxa_thread_info* getSlow() {
      void* obj = pthread_getspecific(__cxa_thread_key);
      if (obj == NULL) {
        obj = malloc(sizeof(__cxa_thread_info));
        if (!obj) {
          // Shouldn't happen, but better be safe than sorry.
          fatalError("Can't allocate thread-specific C++ runtime info block.");
        }
        memset(obj, 0, sizeof(__cxa_thread_info));
        pthread_setspecific(__cxa_thread_key, obj);
      }
      return reinterpret_cast<__cxa_thread_info*>(obj);
    }

  private:
    // Called when a thread is destroyed.
    static void freeObject(void* obj) {
      free(obj);
    }

  };

  // The single static instance, this forces the compiler to register
  // a constructor and destructor for this object in the final library
  // file. They handle the pthread_key_t allocation/deallocation.
  static CxaThreadKey instance;

  void throwException(__cxa_exception *header) {
    __cxa_thread_info *info = CxaThreadKey::getSlow();
    header->unexpectedHandler = info->unexpectedHandler;
    if (!header->unexpectedHandler) {
      header->unexpectedHandler = std::current_unexpected_fn;
    }
    header->terminateHandler = info->terminateHandler;
    if (!header->terminateHandler) {
      header->terminateHandler = std::current_terminate_fn;
    }
    info->globals.uncaughtExceptions += 1;

    _Unwind_Reason_Code ret = _Unwind_RaiseException(&header->unwindHeader);

    // Should not be here
    call_terminate(&header->unwindHeader);
  }

} // anonymous namespace


namespace __cxxabiv1 {

  extern "C" void __cxa_pure_virtual() {
    fatalError("Pure virtual function called!");
  }

  extern "C" __cxa_eh_globals* __cxa_get_globals() {
    __cxa_thread_info* info = CxaThreadKey::getSlow();
    return &info->globals;
  }

  extern "C" __cxa_eh_globals* __cxa_get_globals_fast() {
    __cxa_thread_info* info = CxaThreadKey::getFast();
    return &info->globals;
  }


  extern "C" void *__cxa_allocate_exception(size_t thrown_size) {
    size_t size = thrown_size + sizeof(__cxa_exception);
    __cxa_exception *buffer = static_cast<__cxa_exception*>(malloc(size));
    if (!buffer) {
      // Since Android uses memory-overcommit, we enter here only when
      // the exception object is VERY large. This will propably never happen.
      // Therefore, we decide to use no emergency spaces.
      fatalError("Not enough memory to allocate exception!");
    }

    memset(buffer, 0, sizeof(__cxa_exception));
    return buffer + 1;
  }

  extern "C" void __cxa_free_exception(void* thrown_exception) {
    __cxa_exception *exc = static_cast<__cxa_exception*>(thrown_exception)-1;

    if (exc->exceptionDestructor) {
      try {
        exc->exceptionDestructor(thrown_exception);
      } catch (...) {
        fatalError("Exception destructor has thrown!");
      }
    }

    free(exc);
  }


  extern "C" void __cxa_throw(void* thrown_exc,
                              std::type_info* tinfo,
                              void (*dest)(void*)) {
    __cxa_exception* header = static_cast<__cxa_exception*>(thrown_exc)-1;
    header->exceptionType = tinfo;
    header->exceptionDestructor = dest;

    header->unwindHeader.exception_class = __gxx_exception_class;
    header->unwindHeader.exception_cleanup = defaultExceptionCleanupFunc;

    throwException(header);
  }

  extern "C" void __cxa_rethrow() {
    __cxa_eh_globals *globals = __cxa_get_globals();
    __cxa_exception* header = globals->caughtExceptions;
    _Unwind_Exception* exception = &header->unwindHeader;
    if (!header) {
      fatalError("Attempting to rethrow an exception that doesn't exist!");
    }

    if (isOurCxxException(exception->exception_class)) {
      header->handlerCount = -header->handlerCount; // Set rethrow flag
    } else {
      globals->caughtExceptions = 0;
    }

    throwException(header);
  }


  extern "C" void* __cxa_begin_catch(void* exc) {
    _Unwind_Exception *exception = static_cast<_Unwind_Exception*>(exc);
    __cxa_exception* header = reinterpret_cast<__cxa_exception*>(exception+1)-1;
    __cxa_eh_globals* globals = __cxa_get_globals();

    if (!isOurCxxException(exception->exception_class)) {
      if (globals->caughtExceptions) {
        fatalError("Can't handle non-C++ exception!");
      }
    }

    // Check rethrow flag
    header->handlerCount = (header->handlerCount < 0) ?
      (-header->handlerCount+1) : (header->handlerCount+1);

    if (header != globals->caughtExceptions) {
      header->nextException = globals->caughtExceptions;
      globals->caughtExceptions = header;
    }
    globals->uncaughtExceptions -= 1;

    return header->adjustedPtr;
  }

  extern "C" void __cxa_end_catch() {
    __cxa_eh_globals *globals = __cxa_get_globals_fast();
    __cxa_exception *header = globals->caughtExceptions;
    _Unwind_Exception* exception = &header->unwindHeader;

    if (!header) {
      return;
    }

    if (!isOurCxxException(exception->exception_class)) {
      globals->caughtExceptions = 0;
      _Unwind_DeleteException(exception);
      return;
    }

    int count = header->handlerCount;
    if (count < 0) { // Rethrow
      if (++count == 0) {
        globals->caughtExceptions = header->nextException;
      }
    } else if (--count == 0) {
      globals->caughtExceptions = header->nextException;
      __cxa_free_exception(header+1);
      return;
    } else if (count < 0) {
      fatalError("Internal error during exception handling!");
    }

    header->handlerCount = count;
  }

  extern "C" void* __cxa_get_exception_ptr(void* exceptionObject) {
    __cxa_exception* header =
      reinterpret_cast<__cxa_exception*>(
        reinterpret_cast<_Unwind_Exception *>(exceptionObject)+1)-1;
    return header->adjustedPtr;
  }

} // namespace __cxxabiv1