2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
21 #if defined(__GNUG__) || defined(__CLANG__)
22 #define FOLLY_EXCEPTION_COUNT_USE_CXA_GET_GLOBALS
23 namespace __cxxabiv1 {
24 // forward declaration (originally defined in unwind-cxx.h from from libstdc++)
25 struct __cxa_eh_globals;
26 // declared in cxxabi.h from libstdc++-v3
27 extern "C" __cxa_eh_globals* __cxa_get_globals() noexcept;
29 #elif defined(_MSC_VER) && (_MSC_VER >= 1400) && \
30 (_MSC_VER < 1900) // MSVC++ 8.0 or greater
31 #define FOLLY_EXCEPTION_COUNT_USE_GETPTD
32 // forward declaration (originally defined in mtdll.h from MSVCRT)
34 extern "C" _tiddata* _getptd(); // declared in mtdll.h from MSVCRT
35 #elif defined(_MSC_VER) && (_MSC_VER >= 1900) // MSVC++ 2015
36 #define FOLLY_EXCEPTION_COUNT_USE_STD
38 // Raise an error when trying to use this on unsupported platforms.
39 #error "Unsupported platform, don't include this header."
45 * Returns the number of uncaught exceptions.
47 * This function is based on Evgeny Panasyuk's implementation from here:
48 * http://fburl.com/15190026
50 inline int uncaught_exceptions() noexcept {
51 #if defined(FOLLY_EXCEPTION_COUNT_USE_CXA_GET_GLOBALS)
52 // __cxa_get_globals returns a __cxa_eh_globals* (defined in unwind-cxx.h).
53 // The offset below returns __cxa_eh_globals::uncaughtExceptions.
54 return *(reinterpret_cast<unsigned int*>(static_cast<char*>(
55 static_cast<void*>(__cxxabiv1::__cxa_get_globals())) + sizeof(void*)));
56 #elif defined(FOLLY_EXCEPTION_COUNT_USE_GETPTD)
57 // _getptd() returns a _tiddata* (defined in mtdll.h).
58 // The offset below returns _tiddata::_ProcessingThrow.
59 return *(reinterpret_cast<int*>(static_cast<char*>(
60 static_cast<void*>(_getptd())) + sizeof(void*) * 28 + 0x4 * 8));
61 #elif defined(FOLLY_EXCEPTION_COUNT_USE_STD)
62 return std::uncaught_exceptions();