stdio_sync_filebuf.h
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// Iostreams wrapper for stdio FILE* -*- C++ -*-
// Copyright (C) 2003-2018 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/>.
/** @file ext/stdio_sync_filebuf.h
* This file is a GNU extension to the Standard C++ Library.
*/
#ifndef _STDIO_SYNC_FILEBUF_H
#define _STDIO_SYNC_FILEBUF_H 1
#pragma GCC system_header
#include <streambuf>
#include <unistd.h>
#include <cstdio>
#include <bits/c++io.h> // For __c_file
#include <bits/move.h> // For __exchange
#ifdef _GLIBCXX_USE_WCHAR_T
#include <cwchar>
#endif
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @brief Provides a layer of compatibility for C.
* @ingroup io
*
* This GNU extension provides extensions for working with standard
* C FILE*'s. It must be instantiated by the user with the type of
* character used in the file stream, e.g., stdio_filebuf<char>.
*/
template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
{
public:
// Types:
typedef _CharT char_type;
typedef _Traits traits_type;
typedef typename traits_type::int_type int_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
private:
typedef std::basic_streambuf<_CharT, _Traits> __streambuf_type;
// Underlying stdio FILE
std::__c_file* _M_file;
// Last character gotten. This is used when pbackfail is
// called from basic_streambuf::sungetc()
int_type _M_unget_buf;
public:
explicit
stdio_sync_filebuf(std::__c_file* __f)
: _M_file(__f), _M_unget_buf(traits_type::eof())
{ }
#if __cplusplus >= 201103L
stdio_sync_filebuf(stdio_sync_filebuf&& __fb) noexcept
: __streambuf_type(std::move(__fb)),
_M_file(__fb._M_file), _M_unget_buf(__fb._M_unget_buf)
{
__fb._M_file = nullptr;
__fb._M_unget_buf = traits_type::eof();
}
stdio_sync_filebuf&
operator=(stdio_sync_filebuf&& __fb) noexcept
{
__streambuf_type::operator=(__fb);
_M_file = std::__exchange(__fb._M_file, nullptr);
_M_unget_buf = std::__exchange(__fb._M_unget_buf, traits_type::eof());
return *this;
}
void
swap(stdio_sync_filebuf& __fb)
{
__streambuf_type::swap(__fb);
std::swap(_M_file, __fb._M_file);
std::swap(_M_unget_buf, __fb._M_unget_buf);
}
#endif
/**
* @return The underlying FILE*.
*
* This function can be used to access the underlying C file pointer.
* Note that there is no way for the library to track what you do
* with the file, so be careful.
*/
std::__c_file*
file() { return this->_M_file; }
protected:
int_type
syncgetc();
int_type
syncungetc(int_type __c);
int_type
syncputc(int_type __c);
virtual int_type
underflow()
{
int_type __c = this->syncgetc();
return this->syncungetc(__c);
}
virtual int_type
uflow()
{
// Store the gotten character in case we need to unget it.
_M_unget_buf = this->syncgetc();
return _M_unget_buf;
}
virtual int_type
pbackfail(int_type __c = traits_type::eof())
{
int_type __ret;
const int_type __eof = traits_type::eof();
// Check if the unget or putback was requested
if (traits_type::eq_int_type(__c, __eof)) // unget
{
if (!traits_type::eq_int_type(_M_unget_buf, __eof))
__ret = this->syncungetc(_M_unget_buf);
else // buffer invalid, fail.
__ret = __eof;
}
else // putback
__ret = this->syncungetc(__c);
// The buffered character is no longer valid, discard it.
_M_unget_buf = __eof;
return __ret;
}
virtual std::streamsize
xsgetn(char_type* __s, std::streamsize __n);
virtual int_type
overflow(int_type __c = traits_type::eof())
{
int_type __ret;
if (traits_type::eq_int_type(__c, traits_type::eof()))
{
if (std::fflush(_M_file))
__ret = traits_type::eof();
else
__ret = traits_type::not_eof(__c);
}
else
__ret = this->syncputc(__c);
return __ret;
}
virtual std::streamsize
xsputn(const char_type* __s, std::streamsize __n);
virtual int
sync()
{ return std::fflush(_M_file); }
virtual std::streampos
seekoff(std::streamoff __off, std::ios_base::seekdir __dir,
std::ios_base::openmode = std::ios_base::in | std::ios_base::out)
{
std::streampos __ret(std::streamoff(-1));
int __whence;
if (__dir == std::ios_base::beg)
__whence = SEEK_SET;
else if (__dir == std::ios_base::cur)
__whence = SEEK_CUR;
else
__whence = SEEK_END;
#ifdef _GLIBCXX_USE_LFS
if (!fseeko64(_M_file, __off, __whence))
__ret = std::streampos(ftello64(_M_file));
#else
if (!fseek(_M_file, __off, __whence))
__ret = std::streampos(std::ftell(_M_file));
#endif
return __ret;
}
virtual std::streampos
seekpos(std::streampos __pos,
std::ios_base::openmode __mode =
std::ios_base::in | std::ios_base::out)
{ return seekoff(std::streamoff(__pos), std::ios_base::beg, __mode); }
};
template<>
inline stdio_sync_filebuf<char>::int_type
stdio_sync_filebuf<char>::syncgetc()
{ return std::getc(_M_file); }
template<>
inline stdio_sync_filebuf<char>::int_type
stdio_sync_filebuf<char>::syncungetc(int_type __c)
{ return std::ungetc(__c, _M_file); }
template<>
inline stdio_sync_filebuf<char>::int_type
stdio_sync_filebuf<char>::syncputc(int_type __c)
{ return std::putc(__c, _M_file); }
template<>
inline std::streamsize
stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
{
std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
if (__ret > 0)
_M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
else
_M_unget_buf = traits_type::eof();
return __ret;
}
template<>
inline std::streamsize
stdio_sync_filebuf<char>::xsputn(const char* __s, std::streamsize __n)
{ return std::fwrite(__s, 1, __n, _M_file); }
#ifdef _GLIBCXX_USE_WCHAR_T
template<>
inline stdio_sync_filebuf<wchar_t>::int_type
stdio_sync_filebuf<wchar_t>::syncgetc()
{ return std::getwc(_M_file); }
template<>
inline stdio_sync_filebuf<wchar_t>::int_type
stdio_sync_filebuf<wchar_t>::syncungetc(int_type __c)
{ return std::ungetwc(__c, _M_file); }
template<>
inline stdio_sync_filebuf<wchar_t>::int_type
stdio_sync_filebuf<wchar_t>::syncputc(int_type __c)
{ return std::putwc(__c, _M_file); }
template<>
inline std::streamsize
stdio_sync_filebuf<wchar_t>::xsgetn(wchar_t* __s, std::streamsize __n)
{
std::streamsize __ret = 0;
const int_type __eof = traits_type::eof();
while (__n--)
{
int_type __c = this->syncgetc();
if (traits_type::eq_int_type(__c, __eof))
break;
__s[__ret] = traits_type::to_char_type(__c);
++__ret;
}
if (__ret > 0)
_M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
else
_M_unget_buf = traits_type::eof();
return __ret;
}
template<>
inline std::streamsize
stdio_sync_filebuf<wchar_t>::xsputn(const wchar_t* __s,
std::streamsize __n)
{
std::streamsize __ret = 0;
const int_type __eof = traits_type::eof();
while (__n--)
{
if (traits_type::eq_int_type(this->syncputc(*__s++), __eof))
break;
++__ret;
}
return __ret;
}
#endif
#if _GLIBCXX_EXTERN_TEMPLATE
extern template class stdio_sync_filebuf<char>;
#ifdef _GLIBCXX_USE_WCHAR_T
extern template class stdio_sync_filebuf<wchar_t>;
#endif
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif
move.h
cstdio
std::ios_base::in
static const openmode in
Open for input. Default for ifstream and fstream.
Definition: ios_base.h:443
std::basic_streambuf::traits_type
_Traits traits_type
Definition: streambuf:132
std::streamoff
long long streamoff
Type used by fpos, char_traits<char>, and char_traits<wchar_t>.
Definition: postypes.h:94
std::basic_streambuf::int_type
traits_type::int_type int_type
Definition: streambuf:133
c++io.h
__gnu_cxx::stdio_sync_filebuf::uflow
virtual int_type uflow()
Fetches more data from the controlled sequence.
Definition: stdio_sync_filebuf.h:138
__gnu_cxx
GNU extensions for public use.
std::basic_streambuf::char_type
_CharT char_type
Definition: streambuf:131
std::basic_streambuf::pos_type
traits_type::pos_type pos_type
Definition: streambuf:134
std::streampos
fpos< mbstate_t > streampos
File position for char streams.
Definition: postypes.h:228
streambuf
std::ios_base::cur
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition: ios_base.h:467
__gnu_cxx::stdio_sync_filebuf::sync
virtual int sync()
Synchronizes the buffer arrays with the controlled sequences.
Definition: stdio_sync_filebuf.h:190
cwchar
std::basic_streambuf::off_type
traits_type::off_type off_type
Definition: streambuf:135
std::fpos
Class representing stream positions.
Definition: postypes.h:112
std::ios_base::beg
static const seekdir beg
Request a seek relative to the beginning of the stream.
Definition: ios_base.h:464
std::basic_streambuf
The actual work of input and output (interface).
Definition: iosfwd:80
std::ios_base::out
static const openmode out
Open for output. Default for ofstream and fstream.
Definition: ios_base.h:446
__gnu_cxx::stdio_sync_filebuf
Provides a layer of compatibility for C.This GNU extension provides extensions for working with stand...
Definition: stdio_sync_filebuf.h:57
__gnu_cxx::stdio_sync_filebuf::underflow
virtual int_type underflow()
Fetches more data from the controlled sequence.
Definition: stdio_sync_filebuf.h:131
std::streamsize
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition: postypes.h:98
__gnu_cxx::stdio_sync_filebuf::file
std::__c_file * file()
Definition: stdio_sync_filebuf.h:118