libstdc++-v3/src/c++11/cxx11-ios_failure.cc

// Iostreams base classes -*- C++ -*-

// Copyright (C) 2014-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, 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 General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

//
// ISO C++ 14882:2011: 27.5.3.1.1  Class ios_base::failure
//

#define _GLIBCXX_USE_CXX11_ABI 1
#include <ios>
#include <bits/functexcept.h>
#include <cxxabi.h>

#ifdef _GLIBCXX_USE_NLS
# include <libintl.h>
# define _(msgid)   gettext (msgid)
#else
# define _(msgid)   (msgid)
#endif

#if ! _GLIBCXX_USE_DUAL_ABI
# error This file should not be compiled for this configuration.
#endif

namespace
{
  struct io_error_category : std::error_category
  {
    virtual const char*
    name() const noexcept
    { return "iostream"; }

    _GLIBCXX_DEFAULT_ABI_TAG
    virtual std::string message(int __ec) const
    {
      std::string __msg;
      switch (std::io_errc(__ec))
      {
      case std::io_errc::stream:
          __msg = "iostream error";
          break;
      default:
          __msg = "Unknown error";
          break;
      }
      return __msg;
    }
  };

  const io_error_category&
  __io_category_instance() noexcept
  {
    static const io_error_category __ec{};
    return __ec;
  }

} // namespace

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  const error_category&
  iostream_category() noexcept
  { return __io_category_instance(); }

  ios_base::failure::failure(const string& __str)
  : system_error(io_errc::stream, __str) { }

  ios_base::failure::failure(const string& __str, const error_code& __ec)
  : system_error(__ec, __str) { }

  ios_base::failure::failure(const char* __str, const error_code& __ec)
  : system_error(__ec, __str) { }

  ios_base::failure::~failure()
  { }

  const char*
  ios_base::failure::what() const throw()
  { return runtime_error::what(); }

#if __cpp_rtti
  // These functions are defined in src/c++98/ios_failure.cc
  extern void __construct_ios_failure(void*, const char*);
  extern void __destroy_ios_failure(void*);
  extern bool __is_ios_failure_handler(const __cxxabiv1::__class_type_info*);

  // The type thrown to report errors during stream buffer operations.
  // In addition to the ios::failure[abi:cxx11] base class it also has a
  // member of the gcc4-compatible ios::failure type (in an opaque buffer).
  struct __ios_failure : std::ios::failure
  {
    __ios_failure(const char* s) : failure(s)
    { __construct_ios_failure(buf, runtime_error::what()); }

    __ios_failure(const char* s, const error_code& e) : failure(s, e)
    { __construct_ios_failure(buf, runtime_error::what()); }

    ~__ios_failure()
    { __destroy_ios_failure(buf); }

    // Use std::runtime_error as a proxy for the gcc4-compatible ios::failure
    // (which can't be declared here because _GLIBCXX_USE_CXX11_ABI == 1).
    // There are assertions in src/c++98/ios_failure.cc to ensure the size
    // and alignment assumptions are valid.
    alignas(runtime_error) unsigned char buf[sizeof(runtime_error)];
  };

  // Custom type info for __ios_failure.
  class __iosfail_type_info : __cxxabiv1::__si_class_type_info
  {
    ~__iosfail_type_info();

    bool
    __do_upcast (const __class_type_info *dst_type,
		 void **obj_ptr) const override;
  };

  __iosfail_type_info::~__iosfail_type_info() = default;

  // This function gets called to see if an exception of type
  // __ios_failure can be upcast to the type in a catch handler.
  bool
  __iosfail_type_info::__do_upcast(const __class_type_info *dst_type,
				   void **obj_ptr) const
  {
    // If the handler is for the gcc4-compatible ios::failure type then
    // catch the object stored in __ios_failure::buf instead of
    // the __ios_failure exception object itself.
    if (__is_ios_failure_handler(dst_type))
      {
	*obj_ptr = static_cast<__ios_failure*>(*obj_ptr)->buf;
	return true;
      }
    // Otherwise proceed as normal to see if the handler matches.
    return __class_type_info::__do_upcast(dst_type, obj_ptr);
  }
#else // ! __cpp_rtti
  using __ios_failure = ios::failure;
#endif

  void
  __throw_ios_failure(const char* __s __attribute__((unused)))
  { _GLIBCXX_THROW_OR_ABORT(__ios_failure(_(__s))); }

  void
  __throw_ios_failure(const char* str __attribute__((unused)),
		      int err __attribute__((unused)))
  {
    _GLIBCXX_THROW_OR_ABORT(__ios_failure(_(str),
	  err ? error_code(err, generic_category()) : io_errc::stream));
  }

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace