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Edit File: system_error

// <system_error> -*- C++ -*- // Copyright (C) 2007-2021 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file include/system_error * This is a Standard C++ Library header. */ #ifndef _GLIBCXX_SYSTEM_ERROR #define _GLIBCXX_SYSTEM_ERROR 1 #pragma GCC system_header #if __cplusplus < 201103L # include <bits/c++0x_warning.h> #else #include <bits/c++config.h> #include <bits/error_constants.h> #include <iosfwd> #include <stdexcept> #if __cplusplus > 201703L # include <compare> #endif namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION /** @addtogroup diagnostics * @{ */ class error_code; class error_condition; class system_error; /// is_error_code_enum template<typename _Tp> struct is_error_code_enum : public false_type { }; /// is_error_condition_enum template<typename _Tp> struct is_error_condition_enum : public false_type { }; template<> struct is_error_condition_enum<errc> : public true_type { }; #if __cplusplus > 201402L template <typename _Tp> inline constexpr bool is_error_code_enum_v = is_error_code_enum<_Tp>::value; template <typename _Tp> inline constexpr bool is_error_condition_enum_v = is_error_condition_enum<_Tp>::value; #endif // C++17 /// @} inline namespace _V2 { /** @addtogroup diagnostics * @{ */ /** Abstract base class for types defining a category of error codes. * * An error category defines a context that give meaning to the integer * stored in an `error_code` or `error_condition` object. For example, * the standard `errno` constants such a `EINVAL` and `ENOMEM` are * associated with the "generic" category and other OS-specific error * numbers are associated with the "system" category, but a user-defined * category might give different meanings to the same numerical values. * * @since C++11 */ class error_category { public: constexpr error_category() noexcept = default; virtual ~error_category(); error_category(const error_category&) = delete; error_category& operator=(const error_category&) = delete; virtual const char* name() const noexcept = 0; // We need two different virtual functions here, one returning a // COW string and one returning an SSO string. Their positions in the // vtable must be consistent for dynamic dispatch to work, but which one // the name "message()" finds depends on which ABI the caller is using. #if _GLIBCXX_USE_CXX11_ABI private: _GLIBCXX_DEFAULT_ABI_TAG virtual __cow_string _M_message(int) const; public: _GLIBCXX_DEFAULT_ABI_TAG virtual string message(int) const = 0; #else virtual string message(int) const = 0; private: virtual __sso_string _M_message(int) const; #endif public: virtual error_condition default_error_condition(int __i) const noexcept; virtual bool equivalent(int __i, const error_condition& __cond) const noexcept; virtual bool equivalent(const error_code& __code, int __i) const noexcept; bool operator==(const error_category& __other) const noexcept { return this == &__other; } #if __cpp_lib_three_way_comparison strong_ordering operator<=>(const error_category& __rhs) const noexcept { return std::compare_three_way()(this, &__rhs); } #else bool operator!=(const error_category& __other) const noexcept { return this != &__other; } bool operator<(const error_category& __other) const noexcept { return less<const error_category*>()(this, &__other); } #endif }; // DR 890. /// Error category for `errno` error codes. _GLIBCXX_CONST const error_category& generic_category() noexcept; /// Error category for other error codes defined by the OS. _GLIBCXX_CONST const error_category& system_category() noexcept; /// @} } // end inline namespace /** @addtogroup diagnostics * @{ */ error_code make_error_code(errc) noexcept; /** Class error_code * * This class is a value type storing an integer error number and a * category that gives meaning to the error number. Typically this is done * close the the point where the error happens, to capture the original * error value. * * An `error_code` object can be used to store the original error value * emitted by some subsystem, with a category relevant to the subsystem. * For example, errors from POSIX library functions can be represented by * an `errno` value and the "generic" category, but errors from an HTTP * library might be represented by an HTTP response status code (e.g. 404) * and a custom category defined by the library. * * @since C++11 * @ingroup diagnostics */ class error_code { public: error_code() noexcept : _M_value(0), _M_cat(&system_category()) { } error_code(int __v, const error_category& __cat) noexcept : _M_value(__v), _M_cat(&__cat) { } template<typename _ErrorCodeEnum, typename = typename enable_if<is_error_code_enum<_ErrorCodeEnum>::value>::type> error_code(_ErrorCodeEnum __e) noexcept { *this = make_error_code(__e); } void assign(int __v, const error_category& __cat) noexcept { _M_value = __v; _M_cat = &__cat; } void clear() noexcept { assign(0, system_category()); } // DR 804. template<typename _ErrorCodeEnum> typename enable_if<is_error_code_enum<_ErrorCodeEnum>::value, error_code&>::type operator=(_ErrorCodeEnum __e) noexcept { return *this = make_error_code(__e); } int value() const noexcept { return _M_value; } const error_category& category() const noexcept { return *_M_cat; } error_condition default_error_condition() const noexcept; _GLIBCXX_DEFAULT_ABI_TAG string message() const { return category().message(value()); } explicit operator bool() const noexcept { return _M_value != 0; } // DR 804. private: int _M_value; const error_category* _M_cat; }; // 19.4.2.6 non-member functions /// @relates error_code @{ inline error_code make_error_code(errc __e) noexcept { return error_code(static_cast<int>(__e), generic_category()); } #if __cpp_lib_three_way_comparison inline strong_ordering operator<=>(const error_code& __lhs, const error_code& __rhs) noexcept { if (auto __c = __lhs.category() <=> __rhs.category(); __c != 0) return __c; return __lhs.value() <=> __rhs.value(); } #else inline bool operator<(const error_code& __lhs, const error_code& __rhs) noexcept { return (__lhs.category() < __rhs.category() || (__lhs.category() == __rhs.category() && __lhs.value() < __rhs.value())); } #endif template<typename _CharT, typename _Traits> basic_ostream<_CharT, _Traits>& operator<<(basic_ostream<_CharT, _Traits>& __os, const error_code& __e) { return (__os << __e.category().name() << ':' << __e.value()); } /// @} error_condition make_error_condition(errc) noexcept; /** Class error_condition * * This class represents error conditions that may be visible at an API * boundary. Different `error_code` values that can occur within a library * or module might map to the same `error_condition`. * * An `error_condition` represents something that the program can test for, * and subsequently take appropriate action. * * @since C++11 */ class error_condition { public: error_condition() noexcept : _M_value(0), _M_cat(&generic_category()) { } error_condition(int __v, const error_category& __cat) noexcept : _M_value(__v), _M_cat(&__cat) { } template<typename _ErrorConditionEnum, typename = typename enable_if<is_error_condition_enum<_ErrorConditionEnum>::value>::type> error_condition(_ErrorConditionEnum __e) noexcept { *this = make_error_condition(__e); } void assign(int __v, const error_category& __cat) noexcept { _M_value = __v; _M_cat = &__cat; } // DR 804. template<typename _ErrorConditionEnum> typename enable_if<is_error_condition_enum <_ErrorConditionEnum>::value, error_condition&>::type operator=(_ErrorConditionEnum __e) noexcept { return *this = make_error_condition(__e); } void clear() noexcept { assign(0, generic_category()); } // 19.4.3.4 observers int value() const noexcept { return _M_value; } const error_category& category() const noexcept { return *_M_cat; } _GLIBCXX_DEFAULT_ABI_TAG string message() const { return category().message(value()); } explicit operator bool() const noexcept { return _M_value != 0; } // DR 804. private: int _M_value; const error_category* _M_cat; }; // 19.4.3.6 non-member functions /// Create an `error_condition` representing a standard `errc` condition. /// @relates error_condition inline error_condition make_error_condition(errc __e) noexcept { return error_condition(static_cast<int>(__e), generic_category()); } // 19.4.4 Comparison operators /// @relates error_code inline bool operator==(const error_code& __lhs, const error_code& __rhs) noexcept { return (__lhs.category() == __rhs.category() && __lhs.value() == __rhs.value()); } /// @relates error_code inline bool operator==(const error_code& __lhs, const error_condition& __rhs) noexcept { return (__lhs.category().equivalent(__lhs.value(), __rhs) || __rhs.category().equivalent(__lhs, __rhs.value())); } /// @relates error_condition inline bool operator==(const error_condition& __lhs, const error_condition& __rhs) noexcept { return (__lhs.category() == __rhs.category() && __lhs.value() == __rhs.value()); } #if __cpp_lib_three_way_comparison /// Define an ordering for error_condition objects. /// @relates error_condition inline strong_ordering operator<=>(const error_condition& __lhs, const error_condition& __rhs) noexcept { if (auto __c = __lhs.category() <=> __rhs.category(); __c != 0) return __c; return __lhs.value() <=> __rhs.value(); } #else /// Define an ordering for error_condition objects. /// @relates error_condition inline bool operator<(const error_condition& __lhs, const error_condition& __rhs) noexcept { return (__lhs.category() < __rhs.category() || (__lhs.category() == __rhs.category() && __lhs.value() < __rhs.value())); } /// @relates error_condition inline bool operator==(const error_condition& __lhs, const error_code& __rhs) noexcept { return (__rhs.category().equivalent(__rhs.value(), __lhs) || __lhs.category().equivalent(__rhs, __lhs.value())); } /// @relates error_code inline bool operator!=(const error_code& __lhs, const error_code& __rhs) noexcept { return !(__lhs == __rhs); } /// @relates error_code inline bool operator!=(const error_code& __lhs, const error_condition& __rhs) noexcept { return !(__lhs == __rhs); } /// @relates error_condition inline bool operator!=(const error_condition& __lhs, const error_code& __rhs) noexcept { return !(__lhs == __rhs); } /// @relates error_condition inline bool operator!=(const error_condition& __lhs, const error_condition& __rhs) noexcept { return !(__lhs == __rhs); } #endif // three_way_comparison /// @} /** * @brief An exception type that includes an `error_code` value. * * Typically used to report errors from the operating system and other * low-level APIs. * * @since C++11 * @ingroup exceptions */ class system_error : public std::runtime_error { private: error_code _M_code; public: system_error(error_code __ec = error_code()) : runtime_error(__ec.message()), _M_code(__ec) { } system_error(error_code __ec, const string& __what) : runtime_error(__what + ": " + __ec.message()), _M_code(__ec) { } system_error(error_code __ec, const char* __what) : runtime_error(__what + (": " + __ec.message())), _M_code(__ec) { } system_error(int __v, const error_category& __ecat, const char* __what) : system_error(error_code(__v, __ecat), __what) { } system_error(int __v, const error_category& __ecat) : runtime_error(error_code(__v, __ecat).message()), _M_code(__v, __ecat) { } system_error(int __v, const error_category& __ecat, const string& __what) : runtime_error(__what + ": " + error_code(__v, __ecat).message()), _M_code(__v, __ecat) { } #if __cplusplus >= 201103L system_error (const system_error &) = default; system_error &operator= (const system_error &) = default; #endif virtual ~system_error() noexcept; const error_code& code() const noexcept { return _M_code; } }; _GLIBCXX_END_NAMESPACE_VERSION } // namespace #include <bits/functional_hash.h> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION #ifndef _GLIBCXX_COMPATIBILITY_CXX0X // DR 1182. /// std::hash specialization for error_code. /// @relates error_code template<> struct hash<error_code> : public __hash_base<size_t, error_code> { size_t operator()(const error_code& __e) const noexcept { const size_t __tmp = std::_Hash_impl::hash(__e.value()); return std::_Hash_impl::__hash_combine(&__e.category(), __tmp); } }; #endif // _GLIBCXX_COMPATIBILITY_CXX0X #if __cplusplus >= 201703L // DR 2686. /// std::hash specialization for error_condition. /// @relates error_condition template<> struct hash<error_condition> : public __hash_base<size_t, error_condition> { size_t operator()(const error_condition& __e) const noexcept { const size_t __tmp = std::_Hash_impl::hash(__e.value()); return std::_Hash_impl::__hash_combine(&__e.category(), __tmp); } }; #endif _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif // C++11 #endif // _GLIBCXX_SYSTEM_ERROR