experimental/status-code/posix_code.hpp

0001 /* Proposed SG14 status_code
0002 (C) 2018-2024 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
0003 File Created: Feb 2018
0004
0005
0006 Boost Software License - Version 1.0 - August 17th, 2003
0007
0008 Permission is hereby granted, free of charge, to any person or organization
0009 obtaining a copy of the software and accompanying documentation covered by
0010 this license (the "Software") to use, reproduce, display, distribute,
0011 execute, and transmit the Software, and to prepare derivative works of the
0012 Software, and to permit third-parties to whom the Software is furnished to
0013 do so, all subject to the following:
0014
0015 The copyright notices in the Software and this entire statement, including
0016 the above license grant, this restriction and the following disclaimer,
0017 must be included in all copies of the Software, in whole or in part, and
0018 all derivative works of the Software, unless such copies or derivative
0019 works are solely in the form of machine-executable object code generated by
0020 a source language processor.
0021
0022 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
0023 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
0024 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
0025 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
0026 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
0027 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
0028 DEALINGS IN THE SOFTWARE.
0029 */
0030
0031 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_POSIX_CODE_HPP
0032 #define BOOST_OUTCOME_SYSTEM_ERROR2_POSIX_CODE_HPP
0033
0034 #ifdef BOOST_OUTCOME_SYSTEM_ERROR2_NOT_POSIX
0035 #error <posix_code.hpp> is not includable when BOOST_OUTCOME_SYSTEM_ERROR2_NOT_POSIX is defined!
0036 #endif
0037
0038 #include "quick_status_code_from_enum.hpp"
0039
0040 #include <cstring>  // for strchr and strerror_r
0041
0042 #if defined(_MSC_VER) && !defined(__clang__)
0043 #pragma warning(push)
0044 #pragma warning(disable : 6326)  // constant comparison
0045 #endif
0046
0047 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
0048
0049 // Fix for issue #48 Issue compiling on arm-none-eabi (newlib) with GNU extensions off
0050 #if !defined(_MSC_VER) && !defined(__APPLE__)
0051 namespace detail
0052 {
0053   namespace avoid_string_include
0054   {
0055 #if defined(__GLIBC__) && !defined(__UCLIBC__)
0056     // This returns int for non-glibc strerror_r, but glibc's is particularly weird so we retain it
0057     extern "C" char *strerror_r(int errnum, char *buf, size_t buflen);
0058 #else
0059     extern "C" int strerror_r(int errnum, char *buf, size_t buflen);
0060 #endif
0061   }  // namespace avoid_string_include
0062 }  // namespace detail
0063 #endif
0064
0065 class _posix_code_domain;
0066 //! A POSIX error code, those returned by `errno`.
0067 using posix_code = status_code<_posix_code_domain>;
0068 //! A specialisation of `status_error` for the POSIX error code domain.
0069 using posix_error = status_error<_posix_code_domain>;
0070
0071 namespace mixins
0072 {
0073   template <class Base> struct mixin<Base, _posix_code_domain> : public Base
0074   {
0075     using Base::Base;
0076
0077     //! Returns a `posix_code` for the current value of `errno`.
0078     static posix_code current() noexcept;
0079   };
0080 }  // namespace mixins
0081
0082 /*! The implementation of the domain for POSIX error codes, those returned by `errno`.
0083  */
0084 class _posix_code_domain : public status_code_domain
0085 {
0086   template <class DomainType> friend class status_code;
0087   using _base = status_code_domain;
0088
0089   static _base::string_ref _make_string_ref(int c) noexcept
0090   {
0091     char buffer[1024] = "";
0092 #ifdef _WIN32
0093     strerror_s(buffer, sizeof(buffer), c);
0094 #elif defined(__GLIBC__) && !defined(__UCLIBC__)  // handle glibc's weird strerror_r()
0095     char *s = detail::avoid_string_include::strerror_r(c, buffer, sizeof(buffer));  // NOLINT
0096     if(s != nullptr)
0097     {
0098       strncpy(buffer, s, sizeof(buffer) - 1);  // NOLINT
0099       buffer[1023] = 0;
0100     }
0101 #elif !defined(__APPLE__)
0102     detail::avoid_string_include::strerror_r(c, buffer, sizeof(buffer));
0103 #else
0104     strerror_r(c, buffer, sizeof(buffer));
0105 #endif
0106     size_t length = strlen(buffer);                     // NOLINT
0107     auto *p = static_cast<char *>(malloc(length + 1));  // NOLINT
0108     if(p == nullptr)
0109     {
0110       return _base::string_ref("failed to get message from system");
0111     }
0112     memcpy(p, buffer, length + 1);  // NOLINT
0113     return _base::atomic_refcounted_string_ref(p, length);
0114   }
0115
0116 public:
0117   //! The value type of the POSIX code, which is an `int`
0118   using value_type = int;
0119   using _base::string_ref;
0120
0121   //! Default constructor
0122   constexpr explicit _posix_code_domain(typename _base::unique_id_type id = 0xa59a56fe5f310933) noexcept
0123       : _base(id)
0124   {
0125   }
0126   _posix_code_domain(const _posix_code_domain &) = default;
0127   _posix_code_domain(_posix_code_domain &&) = default;
0128   _posix_code_domain &operator=(const _posix_code_domain &) = default;
0129   _posix_code_domain &operator=(_posix_code_domain &&) = default;
0130   ~_posix_code_domain() = default;
0131
0132   //! Constexpr singleton getter. Returns constexpr posix_code_domain variable.
0133   static inline constexpr const _posix_code_domain &get();
0134
0135   virtual string_ref name() const noexcept override { return string_ref("posix domain"); }  // NOLINT
0136
0137   virtual payload_info_t payload_info() const noexcept override
0138   {
0139     return {sizeof(value_type), sizeof(status_code_domain *) + sizeof(value_type),
0140             (alignof(value_type) > alignof(status_code_domain *)) ? alignof(value_type) : alignof(status_code_domain *)};
0141   }
0142
0143 protected:
0144   virtual bool _do_failure(const status_code<void> &code) const noexcept override                                      // NOLINT
0145   {
0146     assert(code.domain() == *this);                                                                                    // NOLINT
0147     return static_cast<const posix_code &>(code).value() != 0;                                                         // NOLINT
0148   }
0149   virtual bool _do_equivalent(const status_code<void> &code1, const status_code<void> &code2) const noexcept override  // NOLINT
0150   {
0151     assert(code1.domain() == *this);                                                                                   // NOLINT
0152     const auto &c1 = static_cast<const posix_code &>(code1);                                                           // NOLINT
0153     if(code2.domain() == *this)
0154     {
0155       const auto &c2 = static_cast<const posix_code &>(code2);  // NOLINT
0156       return c1.value() == c2.value();
0157     }
0158     if(code2.domain() == generic_code_domain)
0159     {
0160       const auto &c2 = static_cast<const generic_code &>(code2);  // NOLINT
0161       if(static_cast<int>(c2.value()) == c1.value())
0162       {
0163         return true;
0164       }
0165     }
0166     return false;
0167   }
0168   virtual generic_code _generic_code(const status_code<void> &code) const noexcept override  // NOLINT
0169   {
0170     assert(code.domain() == *this);                                                          // NOLINT
0171     const auto &c = static_cast<const posix_code &>(code);                                   // NOLINT
0172     return generic_code(static_cast<errc>(c.value()));
0173   }
0174   virtual string_ref _do_message(const status_code<void> &code) const noexcept override  // NOLINT
0175   {
0176     assert(code.domain() == *this);                                                      // NOLINT
0177     const auto &c = static_cast<const posix_code &>(code);                               // NOLINT
0178     return _make_string_ref(c.value());
0179   }
0180 #if defined(_CPPUNWIND) || defined(__EXCEPTIONS) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
0181   BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const status_code<void> &code) const override  // NOLINT
0182   {
0183     assert(code.domain() == *this);                                                                      // NOLINT
0184     const auto &c = static_cast<const posix_code &>(code);                                               // NOLINT
0185     throw status_error<_posix_code_domain>(c);
0186   }
0187 #endif
0188 };
0189 //! A constexpr source variable for the POSIX code domain, which is that of `errno`. Returned by `_posix_code_domain::get()`.
0190 constexpr _posix_code_domain posix_code_domain;
0191 inline constexpr const _posix_code_domain &_posix_code_domain::get()
0192 {
0193   return posix_code_domain;
0194 }
0195
0196 namespace mixins
0197 {
0198   template <class Base> inline posix_code mixin<Base, _posix_code_domain>::current() noexcept
0199   {
0200     return posix_code(errno);
0201   }
0202 }  // namespace mixins
0203
0204 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END
0205
0206 #if defined(_MSC_VER) && !defined(__clang__)
0207 #pragma warning(pop)
0208 #endif
0209
0210 #endif