1/*
2 * Copyright 2013-present Facebook, Inc.
3 *
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
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17#pragma once
18
19#include <exception>
20
21#if !defined(FOLLY_FORCE_EXCEPTION_COUNT_USE_STD) && \
22 (defined(__GNUG__) || defined(__clang__))
23#define FOLLY_EXCEPTION_COUNT_USE_CXA_GET_GLOBALS
24namespace __cxxabiv1 {
25// forward declaration (originally defined in unwind-cxx.h from from libstdc++)
26struct __cxa_eh_globals;
27// declared in cxxabi.h from libstdc++-v3
28extern "C" __cxa_eh_globals* __cxa_get_globals() noexcept;
29} // namespace __cxxabiv1
30#elif defined(_MSC_VER) && (_MSC_VER >= 1400) && \
31 (_MSC_VER < 1900) // MSVC++ 8.0 or greater
32#define FOLLY_EXCEPTION_COUNT_USE_GETPTD
33// forward declaration (originally defined in mtdll.h from MSVCRT)
34struct _tiddata;
35extern "C" _tiddata* _getptd(); // declared in mtdll.h from MSVCRT
36#elif defined(FOLLY_FORCE_EXCEPTION_COUNT_USE_STD) || \
37 (defined(_MSC_VER) && (_MSC_VER >= 1900)) // MSVC++ 2015
38#define FOLLY_EXCEPTION_COUNT_USE_STD
39#else
40// Raise an error when trying to use this on unsupported platforms.
41#error "Unsupported platform, don't include this header."
42#endif
43
44namespace folly {
45
46/**
47 * Returns the number of uncaught exceptions.
48 *
49 * This function is based on Evgeny Panasyuk's implementation from here:
50 * http://fburl.com/15190026
51 */
52inline int uncaught_exceptions() noexcept {
53#if defined(FOLLY_EXCEPTION_COUNT_USE_CXA_GET_GLOBALS)
54 // __cxa_get_globals returns a __cxa_eh_globals* (defined in unwind-cxx.h).
55 // The offset below returns __cxa_eh_globals::uncaughtExceptions.
56 return *(reinterpret_cast<unsigned int*>(
57 static_cast<char*>(static_cast<void*>(__cxxabiv1::__cxa_get_globals())) +
58 sizeof(void*)));
59#elif defined(FOLLY_EXCEPTION_COUNT_USE_GETPTD)
60 // _getptd() returns a _tiddata* (defined in mtdll.h).
61 // The offset below returns _tiddata::_ProcessingThrow.
62 return *(reinterpret_cast<int*>(
63 static_cast<char*>(static_cast<void*>(_getptd())) + sizeof(void*) * 28 +
64 0x4 * 8));
65#elif defined(FOLLY_EXCEPTION_COUNT_USE_STD)
66 return std::uncaught_exceptions();
67#endif
68}
69
70} // namespace folly
71