Edit File: stdio_sync_filebuf.h
// 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
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