robot/include/boost/outcome/experimental/status-code/posix_code.hpp

/* Proposed SG14 status_code
(C) 2018-2024 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
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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 "quick_status_code_from_enum.hpp"

#include <cstring>  // for strchr and strerror_r

BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN

// Fix for issue #48 Issue compiling on arm-none-eabi (newlib) with GNU extensions off
#if !defined(_MSC_VER) && !defined(__APPLE__)
namespace detail
{
  namespace avoid_string_include
  {
#if defined(__GLIBC__) && !defined(__UCLIBC__)
    // This returns int for non-glibc strerror_r, but glibc's is particularly weird so we retain it
    extern "C" char *strerror_r(int errnum, char *buf, size_t buflen);
#else
    extern "C" int strerror_r(int errnum, char *buf, size_t buflen);
#endif
  }  // namespace avoid_string_include
}  // namespace detail
#endif

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>;

namespace mixins
{
  template <class Base> struct mixin<Base, _posix_code_domain> : public Base
  {
    using Base::Base;

    //! Returns a `posix_code` for the current value of `errno`.
    static posix_code current() noexcept;
  };
}  // namespace mixins

/*! 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;
  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(__GLIBC__) && !defined(__UCLIBC__)  // handle glibc's weird strerror_r()
    char *s = detail::avoid_string_include::strerror_r(c, buffer, sizeof(buffer));  // NOLINT
    if(s != nullptr)
    {
      strncpy(buffer, s, sizeof(buffer) - 1);  // NOLINT
      buffer[1023] = 0;
    }
#elif !defined(__APPLE__)
    detail::avoid_string_include::strerror_r(c, buffer, sizeof(buffer));
#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

  virtual payload_info_t payload_info() const noexcept override
  {
    return {sizeof(value_type), sizeof(status_code_domain *) + sizeof(value_type),
            (alignof(value_type) > alignof(status_code_domain *)) ? alignof(value_type) : alignof(status_code_domain *)};
  }

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;
}

namespace mixins
{
  template <class Base> inline posix_code mixin<Base, _posix_code_domain>::current() noexcept
  {
    return posix_code(errno);
  }
}  // namespace mixins

BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END

#endif