1 /*
2 * Copyright Andrey Semashev 2018 - 2020.
3 * Distributed under the Boost Software License, Version 1.0.
4 * (See accompanying file LICENSE_1_0.txt or copy at
5 * https://www.boost.org/LICENSE_1_0.txt)
6 */
7 /*!
8 * \file uncaught_exceptions.hpp
9 * \author Andrey Semashev
10 * \date 2018-11-10
11 *
12 * \brief This header provides an `uncaught_exceptions` function implementation, which was introduced in C++17.
13 *
14 * The code in this file is based on the implementation by Evgeny Panasyuk:
15 *
16 * https://github.com/panaseleus/stack_unwinding/blob/master/boost/exception/uncaught_exception_count.hpp
17 */
18
19 #ifndef BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_
20 #define BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_
21
22 #include <exception>
23 #include <boost/config.hpp>
24
25 #if defined(BOOST_HAS_PRAGMA_ONCE)
26 #pragma once
27 #endif
28
29 #if defined(__APPLE__)
30 #include <Availability.h>
31 // Apple systems only support std::uncaught_exceptions starting with specific versions:
32 // - Mac OS >= 10.12
33 // - iOS >= 10.0
34 // - tvOS >= 10.0
35 // - watchOS >= 3.0
36 // https://github.com/boostorg/core/issues/80
37 #if (defined(__cpp_lib_uncaught_exceptions) && __cpp_lib_uncaught_exceptions >= 201411) && \
38 ( \
39 (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 101200) || \
40 (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED >= 100000) \
41 )
42 #define BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS
43 #endif
44 // Visual Studio 14.0 supports N4152 std::uncaught_exceptions() but doesn't define __cpp_lib_uncaught_exceptions
45 #elif (defined(__cpp_lib_uncaught_exceptions) && __cpp_lib_uncaught_exceptions >= 201411) || \
46 (defined(_MSC_VER) && _MSC_VER >= 1900)
47 #define BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS
48 #endif
49
50 #if !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
51
52 // cxxabi.h availability macro
53 #if defined(__has_include) && (!defined(BOOST_GCC) || (__GNUC__ >= 5))
54 # if __has_include(<cxxabi.h>)
55 # define BOOST_CORE_HAS_CXXABI_H
56 # endif
57 #elif defined(__GLIBCXX__) || defined(__GLIBCPP__)
58 # define BOOST_CORE_HAS_CXXABI_H
59 #endif
60
61 #if defined(BOOST_CORE_HAS_CXXABI_H)
62 // MinGW GCC 4.4 seem to not work the same way the newer GCC versions do. As a result, __cxa_get_globals based implementation will always return 0.
63 // Just disable it for now and fall back to std::uncaught_exception().
64 // On AIX, xlclang++ does have cxxabi.h but doesn't have __cxa_get_globals (https://github.com/boostorg/core/issues/78).
65 #if !( \
66 (defined(__MINGW32__) && (defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__) < 405)) || \
67 defined(__ibmxl__) \
68 )
69 #include <cxxabi.h>
70 #include <cstring>
71 #define BOOST_CORE_HAS_CXA_GET_GLOBALS
72 // At least on MinGW and Linux, only GCC since 4.7 declares __cxa_get_globals() in cxxabi.h. Older versions of GCC do not expose this function but it's there.
73 // On OpenBSD, it seems, the declaration is also missing.
74 // Note that at least on FreeBSD 11, cxxabi.h declares __cxa_get_globals with a different exception specification, so we can't declare the function unconditionally.
75 // On Linux with clang and libc++ and on OS X, there is a version of cxxabi.h from libc++abi that doesn't declare __cxa_get_globals, but provides __cxa_uncaught_exceptions.
76 // The function only appeared in version _LIBCPPABI_VERSION >= 1002 of the library. Unfortunately, there are linking errors about undefined reference to __cxa_uncaught_exceptions
77 // on Ubuntu Trusty and OS X, so we avoid using it and forward-declare __cxa_get_globals instead.
78 // On QNX SDP 7.0 (QCC 5.4.0), there are multiple cxxabi.h, one from glibcxx from gcc and another from libc++abi from LLVM. Which one is included will be determined by the qcc
79 // command line arguments (-V and/or -Y; http://www.qnx.com/developers/docs/7.0.0/#com.qnx.doc.neutrino.utilities/topic/q/qcc.html). The LLVM libc++abi is missing the declaration
80 // of __cxa_get_globals but it is also patched by QNX developers to not define _LIBCPPABI_VERSION. Older QNX SDP versions, up to and including 6.6, don't provide LLVM and libc++abi.
81 // See https://github.com/boostorg/core/issues/59.
82 #if !defined(__FreeBSD__) && \
83 ( \
84 (defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__) < 407) || \
85 defined(__OpenBSD__) || \
86 (defined(__QNXNTO__) && !defined(__GLIBCXX__) && !defined(__GLIBCPP__)) || \
87 defined(_LIBCPPABI_VERSION) \
88 )
89 namespace __cxxabiv1 {
90 struct __cxa_eh_globals;
91 #if defined(__OpenBSD__)
92 extern "C" __cxa_eh_globals* __cxa_get_globals();
93 #else
94 extern "C" __cxa_eh_globals* __cxa_get_globals() BOOST_NOEXCEPT_OR_NOTHROW __attribute__((__const__));
95 #endif
96 } // namespace __cxxabiv1
97 #endif
98 #endif
99 #endif // defined(BOOST_CORE_HAS_CXXABI_H)
100
101 #if defined(_MSC_VER) && _MSC_VER >= 1400
102 #include <cstring>
103 #define BOOST_CORE_HAS_GETPTD
104 namespace boost {
105 namespace core {
106 namespace detail {
107 extern "C" void* _getptd();
108 } // namespace detail
109 } // namespace core
110 } // namespace boost
111 #endif // defined(_MSC_VER) && _MSC_VER >= 1400
112
113 #endif // !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
114
115 #if !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS) && !defined(BOOST_CORE_HAS_CXA_GET_GLOBALS) && !defined(BOOST_CORE_HAS_GETPTD)
116 //! This macro is defined when `uncaught_exceptions` is not guaranteed to return values greater than 1 if multiple exceptions are pending
117 #define BOOST_CORE_UNCAUGHT_EXCEPTIONS_EMULATED
118 #endif
119
120 namespace boost {
121
122 namespace core {
123
124 //! Returns the number of currently pending exceptions
uncaught_exceptions()125 inline unsigned int uncaught_exceptions() BOOST_NOEXCEPT
126 {
127 #if defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
128 // C++17 implementation
129 return static_cast< unsigned int >(std::uncaught_exceptions());
130 #elif defined(BOOST_CORE_HAS_CXA_GET_GLOBALS)
131 // Tested on {clang 3.2,GCC 3.5.6,GCC 4.1.2,GCC 4.4.6,GCC 4.4.7}x{x32,x64}
132 unsigned int count;
133 std::memcpy(&count, reinterpret_cast< const unsigned char* >(::abi::__cxa_get_globals()) + sizeof(void*), sizeof(count)); // __cxa_eh_globals::uncaughtExceptions, x32 offset - 0x4, x64 - 0x8
134 return count;
135 #elif defined(BOOST_CORE_HAS_GETPTD)
136 // MSVC specific. Tested on {MSVC2005SP1,MSVC2008SP1,MSVC2010SP1,MSVC2012}x{x32,x64}.
137 unsigned int count;
138 std::memcpy(&count, static_cast< const unsigned char* >(boost::core::detail::_getptd()) + (sizeof(void*) == 8u ? 0x100 : 0x90), sizeof(count)); // _tiddata::_ProcessingThrow, x32 offset - 0x90, x64 - 0x100
139 return count;
140 #else
141 // Portable C++03 implementation. Does not allow to detect multiple nested exceptions.
142 return static_cast< unsigned int >(std::uncaught_exception());
143 #endif
144 }
145
146 } // namespace core
147
148 } // namespace boost
149
150 #undef BOOST_CORE_HAS_CXXABI_H
151 #undef BOOST_CORE_HAS_CXA_GET_GLOBALS
152 #undef BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS
153 #undef BOOST_CORE_HAS_GETPTD
154
155 #endif // BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_
156