1 // File descriptor layer for filebuf -*- C++ -*- 2 3 // Copyright (C) 2002-2018 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file ext/stdio_filebuf.h 26 * This file is a GNU extension to the Standard C++ Library. 27 */ 28 29 #ifndef _STDIO_FILEBUF_H 30 #define _STDIO_FILEBUF_H 1 31 32 #pragma GCC system_header 33 34 #include <fstream> 35 36 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 37 { 38 _GLIBCXX_BEGIN_NAMESPACE_VERSION 39 40 /** 41 * @brief Provides a layer of compatibility for C/POSIX. 42 * @ingroup io 43 * 44 * This GNU extension provides extensions for working with standard C 45 * FILE*'s and POSIX file descriptors. It must be instantiated by the 46 * user with the type of character used in the file stream, e.g., 47 * stdio_filebuf<char>. 48 */ 49 template<typename _CharT, typename _Traits = std::char_traits<_CharT> > 50 class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits> 51 { 52 public: 53 // Types: 54 typedef _CharT char_type; 55 typedef _Traits traits_type; 56 typedef typename traits_type::int_type int_type; 57 typedef typename traits_type::pos_type pos_type; 58 typedef typename traits_type::off_type off_type; 59 typedef std::size_t size_t; 60 61 public: 62 /** 63 * deferred initialization 64 */ 65 stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {} 66 67 /** 68 * @param __fd An open file descriptor. 69 * @param __mode Same meaning as in a standard filebuf. 70 * @param __size Optimal or preferred size of internal buffer, 71 * in chars. 72 * 73 * This constructor associates a file stream buffer with an open 74 * POSIX file descriptor. The file descriptor will be automatically 75 * closed when the stdio_filebuf is closed/destroyed. 76 */ 77 stdio_filebuf(int __fd, std::ios_base::openmode __mode, 78 size_t __size = static_cast<size_t>(BUFSIZ)); 79 80 /** 81 * @param __f An open @c FILE*. 82 * @param __mode Same meaning as in a standard filebuf. 83 * @param __size Optimal or preferred size of internal buffer, 84 * in chars. Defaults to system's @c BUFSIZ. 85 * 86 * This constructor associates a file stream buffer with an open 87 * C @c FILE*. The @c FILE* will not be automatically closed when the 88 * stdio_filebuf is closed/destroyed. 89 */ 90 stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode, 91 size_t __size = static_cast<size_t>(BUFSIZ)); 92 93 /** 94 * Closes the external data stream if the file descriptor constructor 95 * was used. 96 */ 97 virtual 98 ~stdio_filebuf(); 99 100 #if __cplusplus >= 201103L 101 stdio_filebuf(stdio_filebuf&&) = default; 102 stdio_filebuf& operator=(stdio_filebuf&&) = default; 103 104 void 105 swap(stdio_filebuf& __fb) 106 { std::basic_filebuf<_CharT, _Traits>::swap(__fb); } 107 #endif 108 109 /** 110 * @return The underlying file descriptor. 111 * 112 * Once associated with an external data stream, this function can be 113 * used to access the underlying POSIX file descriptor. Note that 114 * there is no way for the library to track what you do with the 115 * descriptor, so be careful. 116 */ 117 int 118 fd() { return this->_M_file.fd(); } 119 120 /** 121 * @return The underlying FILE*. 122 * 123 * This function can be used to access the underlying "C" file pointer. 124 * Note that there is no way for the library to track what you do 125 * with the file, so be careful. 126 */ 127 std::__c_file* 128 file() { return this->_M_file.file(); } 129 }; 130 131 template<typename _CharT, typename _Traits> 132 stdio_filebuf<_CharT, _Traits>::~stdio_filebuf() 133 { } 134 135 template<typename _CharT, typename _Traits> 136 stdio_filebuf<_CharT, _Traits>:: 137 stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size) 138 { 139 this->_M_file.sys_open(__fd, __mode); 140 if (this->is_open()) 141 { 142 this->_M_mode = __mode; 143 this->_M_buf_size = __size; 144 this->_M_allocate_internal_buffer(); 145 this->_M_reading = false; 146 this->_M_writing = false; 147 this->_M_set_buffer(-1); 148 } 149 } 150 151 template<typename _CharT, typename _Traits> 152 stdio_filebuf<_CharT, _Traits>:: 153 stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode, 154 size_t __size) 155 { 156 this->_M_file.sys_open(__f, __mode); 157 if (this->is_open()) 158 { 159 this->_M_mode = __mode; 160 this->_M_buf_size = __size; 161 this->_M_allocate_internal_buffer(); 162 this->_M_reading = false; 163 this->_M_writing = false; 164 this->_M_set_buffer(-1); 165 } 166 } 167 168 _GLIBCXX_END_NAMESPACE_VERSION 169 } // namespace 170 171 #endif 172