OTS/OTSCPP/Tools/boost/outcome/experimental/status-code/posix_code.hpp

/* Proposed SG14 status_code
(C) 2018-2020 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
File Created: Feb 2018


Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
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must be included in all copies of the Software, in whole or in part, and
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*/

#ifndef BOOST_OUTCOME_SYSTEM_ERROR2_POSIX_CODE_HPP
#define BOOST_OUTCOME_SYSTEM_ERROR2_POSIX_CODE_HPP

#ifdef BOOST_OUTCOME_SYSTEM_ERROR2_NOT_POSIX
#error <posix_code.hpp> is not includable when BOOST_OUTCOME_SYSTEM_ERROR2_NOT_POSIX is defined!
#endif

#include "generic_code.hpp"

#include <cstring>  // for strchr and strerror_r

BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN

class _posix_code_domain;
//! A POSIX error code, those returned by `errno`.
using posix_code = status_code<_posix_code_domain>;
//! A specialisation of `status_error` for the POSIX error code domain.
using posix_error = status_error<_posix_code_domain>;

/*! The implementation of the domain for POSIX error codes, those returned by `errno`.
*/
class _posix_code_domain : public status_code_domain
{
  template <class DomainType> friend class status_code;
  template <class StatusCode> friend class detail::indirecting_domain;
  using _base = status_code_domain;

  static _base::string_ref _make_string_ref(int c) noexcept
  {
    char buffer[1024] = "";
#ifdef _WIN32
    strerror_s(buffer, sizeof(buffer), c);
#elif defined(__gnu_linux__) && !defined(__ANDROID__)  // handle glibc's weird strerror_r()
    char *s = strerror_r(c, buffer, sizeof(buffer));   // NOLINT
    if(s != nullptr)
    {
      strncpy(buffer, s, sizeof(buffer));  // NOLINT
      buffer[1023] = 0;
    }
#else
    strerror_r(c, buffer, sizeof(buffer));
#endif
    size_t length = strlen(buffer);  // NOLINT
    auto *p = static_cast<char *>(malloc(length + 1));  // NOLINT
    if(p == nullptr)
    {
      return _base::string_ref("failed to get message from system");
    }
    memcpy(p, buffer, length + 1);  // NOLINT
    return _base::atomic_refcounted_string_ref(p, length);
  }

public:
  //! The value type of the POSIX code, which is an `int`
  using value_type = int;
  using _base::string_ref;

  //! Default constructor
  constexpr explicit _posix_code_domain(typename _base::unique_id_type id = 0xa59a56fe5f310933) noexcept : _base(id) {}
  _posix_code_domain(const _posix_code_domain &) = default;
  _posix_code_domain(_posix_code_domain &&) = default;
  _posix_code_domain &operator=(const _posix_code_domain &) = default;
  _posix_code_domain &operator=(_posix_code_domain &&) = default;
  ~_posix_code_domain() = default;

  //! Constexpr singleton getter. Returns constexpr posix_code_domain variable.
  static inline constexpr const _posix_code_domain &get();

  virtual string_ref name() const noexcept override { return string_ref("posix domain"); }  // NOLINT
protected:
  virtual bool _do_failure(const status_code<void> &code) const noexcept override  // NOLINT
  {
    assert(code.domain() == *this);  // NOLINT
    return static_cast<const posix_code &>(code).value() != 0;  // NOLINT
  }
  virtual bool _do_equivalent(const status_code<void> &code1, const status_code<void> &code2) const noexcept override  // NOLINT
  {
    assert(code1.domain() == *this);  // NOLINT
    const auto &c1 = static_cast<const posix_code &>(code1);  // NOLINT
    if(code2.domain() == *this)
    {
      const auto &c2 = static_cast<const posix_code &>(code2);  // NOLINT
      return c1.value() == c2.value();
    }
    if(code2.domain() == generic_code_domain)
    {
      const auto &c2 = static_cast<const generic_code &>(code2);  // NOLINT
      if(static_cast<int>(c2.value()) == c1.value())
      {
        return true;
      }
    }
    return false;
  }
  virtual generic_code _generic_code(const status_code<void> &code) const noexcept override  // NOLINT
  {
    assert(code.domain() == *this);  // NOLINT
    const auto &c = static_cast<const posix_code &>(code);  // NOLINT
    return generic_code(static_cast<errc>(c.value()));
  }
  virtual string_ref _do_message(const status_code<void> &code) const noexcept override  // NOLINT
  {
    assert(code.domain() == *this);  // NOLINT
    const auto &c = static_cast<const posix_code &>(code);  // NOLINT
    return _make_string_ref(c.value());
  }
#if defined(_CPPUNWIND) || defined(__EXCEPTIONS) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
  BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const status_code<void> &code) const override  // NOLINT
  {
    assert(code.domain() == *this);  // NOLINT
    const auto &c = static_cast<const posix_code &>(code);  // NOLINT
    throw status_error<_posix_code_domain>(c);
  }
#endif
};
//! A constexpr source variable for the POSIX code domain, which is that of `errno`. Returned by `_posix_code_domain::get()`.
constexpr _posix_code_domain posix_code_domain;
inline constexpr const _posix_code_domain &_posix_code_domain::get()
{
  return posix_code_domain;
}

BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END

#endif