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 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
0043
0044 // Fix for issue #48 Issue compiling on arm-none-eabi (newlib) with GNU extensions off
0045 #if !defined(_MSC_VER) && !defined(__APPLE__)
0046 namespace detail
0047 {
0048   namespace avoid_string_include
0049   {
0050 #if defined(__GLIBC__) && !defined(__UCLIBC__)
0051     // This returns int for non-glibc strerror_r, but glibc's is particularly weird so we retain it
0052     extern "C" char *strerror_r(int errnum, char *buf, size_t buflen);
0053 #else
0054     extern "C" int strerror_r(int errnum, char *buf, size_t buflen);
0055 #endif
0056   }  // namespace avoid_string_include
0057 }  // namespace detail
0058 #endif
0059
0060 class _posix_code_domain;
0061 //! A POSIX error code, those returned by `errno`.
0062 using posix_code = status_code<_posix_code_domain>;
0063 //! A specialisation of `status_error` for the POSIX error code domain.
0064 using posix_error = status_error<_posix_code_domain>;
0065
0066 namespace mixins
0067 {
0068   template <class Base> struct mixin<Base, _posix_code_domain> : public Base
0069   {
0070     using Base::Base;
0071
0072     //! Returns a `posix_code` for the current value of `errno`.
0073     static posix_code current() noexcept;
0074   };
0075 }  // namespace mixins
0076
0077 /*! The implementation of the domain for POSIX error codes, those returned by `errno`.
0078  */
0079 class _posix_code_domain : public status_code_domain
0080 {
0081   template <class DomainType> friend class status_code;
0082   using _base = status_code_domain;
0083
0084   static _base::string_ref _make_string_ref(int c) noexcept
0085   {
0086     char buffer[1024] = "";
0087 #ifdef _WIN32
0088     strerror_s(buffer, sizeof(buffer), c);
0089 #elif defined(__GLIBC__) && !defined(__UCLIBC__)  // handle glibc's weird strerror_r()
0090     char *s = detail::avoid_string_include::strerror_r(c, buffer, sizeof(buffer));  // NOLINT
0091     if(s != nullptr)
0092     {
0093       strncpy(buffer, s, sizeof(buffer) - 1);  // NOLINT
0094       buffer[1023] = 0;
0095     }
0096 #elif !defined(__APPLE__)
0097     detail::avoid_string_include::strerror_r(c, buffer, sizeof(buffer));
0098 #else
0099     strerror_r(c, buffer, sizeof(buffer));
0100 #endif
0101     size_t length = strlen(buffer);                     // NOLINT
0102     auto *p = static_cast<char *>(malloc(length + 1));  // NOLINT
0103     if(p == nullptr)
0104     {
0105       return _base::string_ref("failed to get message from system");
0106     }
0107     memcpy(p, buffer, length + 1);  // NOLINT
0108     return _base::atomic_refcounted_string_ref(p, length);
0109   }
0110
0111 public:
0112   //! The value type of the POSIX code, which is an `int`
0113   using value_type = int;
0114   using _base::string_ref;
0115
0116   //! Default constructor
0117   constexpr explicit _posix_code_domain(typename _base::unique_id_type id = 0xa59a56fe5f310933) noexcept
0118       : _base(id)
0119   {
0120   }
0121   _posix_code_domain(const _posix_code_domain &) = default;
0122   _posix_code_domain(_posix_code_domain &&) = default;
0123   _posix_code_domain &operator=(const _posix_code_domain &) = default;
0124   _posix_code_domain &operator=(_posix_code_domain &&) = default;
0125   ~_posix_code_domain() = default;
0126
0127   //! Constexpr singleton getter. Returns constexpr posix_code_domain variable.
0128   static inline constexpr const _posix_code_domain &get();
0129
0130   virtual string_ref name() const noexcept override { return string_ref("posix domain"); }  // NOLINT
0131
0132   virtual payload_info_t payload_info() const noexcept override
0133   {
0134     return {sizeof(value_type), sizeof(status_code_domain *) + sizeof(value_type),
0135             (alignof(value_type) > alignof(status_code_domain *)) ? alignof(value_type) : alignof(status_code_domain *)};
0136   }
0137
0138 protected:
0139   virtual bool _do_failure(const status_code<void> &code) const noexcept override                                      // NOLINT
0140   {
0141     assert(code.domain() == *this);                                                                                    // NOLINT
0142     return static_cast<const posix_code &>(code).value() != 0;                                                         // NOLINT
0143   }
0144   virtual bool _do_equivalent(const status_code<void> &code1, const status_code<void> &code2) const noexcept override  // NOLINT
0145   {
0146     assert(code1.domain() == *this);                                                                                   // NOLINT
0147     const auto &c1 = static_cast<const posix_code &>(code1);                                                           // NOLINT
0148     if(code2.domain() == *this)
0149     {
0150       const auto &c2 = static_cast<const posix_code &>(code2);  // NOLINT
0151       return c1.value() == c2.value();
0152     }
0153     if(code2.domain() == generic_code_domain)
0154     {
0155       const auto &c2 = static_cast<const generic_code &>(code2);  // NOLINT
0156       if(static_cast<int>(c2.value()) == c1.value())
0157       {
0158         return true;
0159       }
0160     }
0161     return false;
0162   }
0163   virtual generic_code _generic_code(const status_code<void> &code) const noexcept override  // NOLINT
0164   {
0165     assert(code.domain() == *this);                                                          // NOLINT
0166     const auto &c = static_cast<const posix_code &>(code);                                   // NOLINT
0167     return generic_code(static_cast<errc>(c.value()));
0168   }
0169   virtual string_ref _do_message(const status_code<void> &code) const noexcept override  // NOLINT
0170   {
0171     assert(code.domain() == *this);                                                      // NOLINT
0172     const auto &c = static_cast<const posix_code &>(code);                               // NOLINT
0173     return _make_string_ref(c.value());
0174   }
0175 #if defined(_CPPUNWIND) || defined(__EXCEPTIONS) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
0176   BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const status_code<void> &code) const override  // NOLINT
0177   {
0178     assert(code.domain() == *this);                                                                      // NOLINT
0179     const auto &c = static_cast<const posix_code &>(code);                                               // NOLINT
0180     throw status_error<_posix_code_domain>(c);
0181   }
0182 #endif
0183 };
0184 //! A constexpr source variable for the POSIX code domain, which is that of `errno`. Returned by `_posix_code_domain::get()`.
0185 constexpr _posix_code_domain posix_code_domain;
0186 inline constexpr const _posix_code_domain &_posix_code_domain::get()
0187 {
0188   return posix_code_domain;
0189 }
0190
0191 namespace mixins
0192 {
0193   template <class Base> inline posix_code mixin<Base, _posix_code_domain>::current() noexcept
0194   {
0195     return posix_code(errno);
0196   }
0197 }  // namespace mixins
0198
0199 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END
0200
0201 #endif