syscall_wrapper_impl.hpp

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/******************************************************************************
** Copyright © 2020 by J.M.McGuiness, coder@hussar.me.uk
**
** This library is free software; you can redistribute it and/or
** modify it under the terms of the GNU Lesser General Public
** License as published by the Free Software Foundation; either
** version 2.1 of the License, 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
** Lesser General Public License for more details.
**
** You should have received a copy of the GNU Lesser General Public
** License along with this library; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
 
namespace jmmcg { namespace LIBJMMCG_VER_NAMESPACE {
 
template<class FailureTraits, class ...FnArgs>
template<class HandleError>
inline auto
syscall::traits_base<FailureTraits, FnArgs...>::report(fn_ret_code ret, HandleError &&handle_error) noexcept(false) {
   if (LIKELY(!failure_detection::result(ret, reinterpret_cast<fn_ret_code>(failure_code::value)))) {
      return ret;
   } else {
      handle_error();
      return fn_ret_code{};
   }
}
 
template<class FailureTraits, class ...Args>
void
syscall::traits_base<FailureTraits, Args...>::report_error(int err, char const *file_name, unsigned line_num, char const *fn_name, tchar const * const rev_info, tchar const * const err_msg, fn_ret_code (*fn)(Args...), Args ...args) noexcept(false) {
   info::function fun(
      line_num,
      fn_name,
      typeid(fn)
   );
   fun.add_args(info::function::argument(exception_t::thread_traits::demangle_name(typeid(args)).begin(), args)...);
   throw exception_t(err_msg, std::move(fun), info::revision(rev_info, file_name), err);
}
 
template<class FailureTraits, class ...Args>
inline auto
syscall::simple_report_traits<FailureTraits, Args...>::select_error(int err, char const *file_name, unsigned line_num, char const *fn_name, tchar const * const rev_info, tchar const * const err_msg, fn_ret_code (*fn)(Args...), Args ...args) {
   return base_t::report_error(err, file_name, line_num, fn_name, rev_info, err_msg, fn, args...);
}
 
template<class CaseStatements, class FailureTraits, class ...Args>
inline constexpr auto
syscall::switch_traits<CaseStatements, FailureTraits, Args...>::select_error(int err, char const *file_name, unsigned line_num, char const *fn_name, tchar const * const rev_info, tchar const * const err_msg, fn_ret_code (*fn)(Args...), Args ...args) {
   enum : std::size_t {
      num_statements=std::tuple_size<std::decay_t<case_statements>>::value
   };
   BOOST_MPL_ASSERT_RELATION(num_statements, >, 1);
   private_::unroller<num_statements-1, case_statements>::result(
      err,
      [err, file_name, line_num, fn_name, rev_info, err_msg, fn, args...]() {
         base_t::report_error(err, file_name, line_num, fn_name, rev_info, err_msg, fn, args...);
      }
   );
}
 
template<
   template<class, class ...> class Traits,
   template<class, template<class> class, template<class> class> class FailureTraits,
   template<class> class FailureCode,
   template<class> class FailureDetection,
   class FnReturnType,
   class ...FnArgs,
   class ...PassedInArgs
>
inline FnReturnType
syscall::process([[maybe_unused]] char const * const file_name, [[maybe_unused]] unsigned line_num, [[maybe_unused]] char const * const fn_name, [[maybe_unused]] tchar const * const rev_info, [[maybe_unused]] tchar const * const err_msg, FnReturnType (*fn)(FnArgs...), PassedInArgs ...args) noexcept(std::is_same<FnReturnType, void>::value) {
   using traits_t=Traits<
      FailureTraits<
         FnReturnType,
         FailureCode,
         FailureDetection
      >,
      FnArgs...
   >;
   if constexpr (std::is_same<FnReturnType, void>::value) {
      fn(static_cast<FnArgs>(args)...);
   } else {
      auto ret=fn(static_cast<FnArgs>(args)...);
      return traits_t::report(
         ret,
         std::bind(traits_t::select_error, errno, file_name, line_num, fn_name, rev_info, err_msg, fn, args...)
      );
   }
}
 
} }