00001 // File descriptor layer for filebuf -*- C++ -*- 00002 00003 // Copyright (C) 2002 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 2, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // You should have received a copy of the GNU General Public License along 00017 // with this library; see the file COPYING. If not, write to the Free 00018 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, 00019 // USA. 00020 00021 // As a special exception, you may use this file as part of a free software 00022 // library without restriction. Specifically, if other files instantiate 00023 // templates or use macros or inline functions from this file, or you compile 00024 // this file and link it with other files to produce an executable, this 00025 // file does not by itself cause the resulting executable to be covered by 00026 // the GNU General Public License. This exception does not however 00027 // invalidate any other reasons why the executable file might be covered by 00028 // the GNU General Public License. 00029 00030 /** @file ext/stdio_filebuf.h 00031 * This file is a GNU extension to the Standard C++ Library. 00032 */ 00033 00034 #ifndef _EXT_STDIO_FILEBUF 00035 #define _EXT_STDIO_FILEBUF 00036 00037 #pragma GCC system_header 00038 #include <fstream> 00039 00040 namespace __gnu_cxx 00041 { 00042 /** 00043 * @class stdio_filebuf ext/stdio_filebuf.h <ext/stdio_filebuf.h> 00044 * @brief Provides a layer of compatibility for C/POSIX. 00045 * 00046 * This GNU extension provides extensions for working with standard C 00047 * FILE*'s and POSIX file descriptors. It must be instantiated by the 00048 * user with the type of character used in the file stream, e.g., 00049 * stdio_filebuf<char>. 00050 */ 00051 template<typename _CharT, typename _Traits = std::char_traits<_CharT> > 00052 class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits> 00053 { 00054 public: 00055 // Types: 00056 typedef _CharT char_type; 00057 typedef _Traits traits_type; 00058 typedef typename traits_type::int_type int_type; 00059 typedef typename traits_type::pos_type pos_type; 00060 typedef typename traits_type::off_type off_type; 00061 typedef std::size_t size_t; 00062 00063 protected: 00064 // Stack-based buffer for unbuffered input. 00065 char_type _M_unbuf[4]; 00066 00067 public: 00068 /** 00069 * @param fd An open file descriptor. 00070 * @param mode Same meaning as in a standard filebuf. 00071 * @param del Whether to close the file on destruction. 00072 * @param size Optimal or preferred size of internal buffer, in bytes. 00073 * 00074 * This constructor associates a file stream buffer with an open 00075 * POSIX file descriptor. Iff @a del is true, then the associated 00076 * file will be closed when the stdio_filebuf is closed/destroyed. 00077 */ 00078 stdio_filebuf(int __fd, std::ios_base::openmode __mode, bool __del, 00079 size_t __size); 00080 00081 /** 00082 * @param f An open @c FILE*. 00083 * @param mode Same meaning as in a standard filebuf. 00084 * @param size Optimal or preferred size of internal buffer, in bytes. 00085 * Defaults to system's @c BUFSIZ. 00086 * 00087 * This constructor associates a file stream buffer with an open 00088 * C @c FILE*. The @c FILE* will not be automatically closed when the 00089 * stdio_filebuf is closed/destroyed. 00090 */ 00091 stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode, 00092 size_t __size = static_cast<size_t>(BUFSIZ)); 00093 00094 /** 00095 * Possibly closes the external data stream, in the case of the file 00096 * descriptor constructor and @c del @c == @c true. 00097 */ 00098 virtual 00099 ~stdio_filebuf(); 00100 00101 /** 00102 * @return The underlying file descriptor. 00103 * 00104 * Once associated with an external data stream, this function can be 00105 * used to access the underlying POSIX file descriptor. Note that 00106 * there is no way for the library to track what you do with the 00107 * descriptor, so be careful. 00108 */ 00109 int 00110 fd() 00111 { return _M_file.fd(); } 00112 }; 00113 00114 template<typename _CharT, typename _Traits> 00115 stdio_filebuf<_CharT, _Traits>::~stdio_filebuf() 00116 { } 00117 00118 template<typename _CharT, typename _Traits> 00119 stdio_filebuf<_CharT, _Traits>:: 00120 stdio_filebuf(int __fd, std::ios_base::openmode __mode, bool __del, 00121 size_t __size) 00122 { 00123 _M_file.sys_open(__fd, __mode, __del); 00124 if (this->is_open()) 00125 { 00126 _M_mode = __mode; 00127 if (__size > 0 && __size < 4) 00128 { 00129 // Specify not to use an allocated buffer. 00130 _M_buf = _M_unbuf; 00131 _M_buf_size = __size; 00132 _M_buf_size_opt = 0; 00133 } 00134 else 00135 { 00136 _M_buf_size_opt = __size; 00137 _M_allocate_internal_buffer(); 00138 } 00139 _M_set_indeterminate(); 00140 } 00141 } 00142 00143 template<typename _CharT, typename _Traits> 00144 stdio_filebuf<_CharT, _Traits>:: 00145 stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode, 00146 size_t __size) 00147 { 00148 _M_file.sys_open(__f, __mode); 00149 if (this->is_open()) 00150 { 00151 _M_mode = __mode; 00152 if (__size > 0 && __size < 4) 00153 { 00154 // Specify not to use an allocated buffer. 00155 _M_buf = _M_unbuf; 00156 _M_buf_size = __size; 00157 _M_buf_size_opt = 0; 00158 } 00159 else 00160 { 00161 _M_buf_size_opt = __size; 00162 _M_allocate_internal_buffer(); 00163 } 00164 _M_set_indeterminate(); 00165 } 00166 } 00167 } // namespace __gnu_cxx 00168 00169 #endif /* _EXT_STDIO_FILEBUF */