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1 // File descriptor layer for filebuf -*- C++ -*-
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2
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3 // Copyright (C) 2002-2020 Free Software Foundation, Inc.
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111
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4 //
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5 // This file is part of the GNU ISO C++ Library. This library is free
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6 // software; you can redistribute it and/or modify it under the
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7 // terms of the GNU General Public License as published by the
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8 // Free Software Foundation; either version 3, or (at your option)
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9 // any later version.
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10
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11 // This library is distributed in the hope that it will be useful,
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12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 // GNU General Public License for more details.
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15
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16 // Under Section 7 of GPL version 3, you are granted additional
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17 // permissions described in the GCC Runtime Library Exception, version
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18 // 3.1, as published by the Free Software Foundation.
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19
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20 // You should have received a copy of the GNU General Public License and
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21 // a copy of the GCC Runtime Library Exception along with this program;
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22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 // <http://www.gnu.org/licenses/>.
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24
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25 /** @file ext/stdio_filebuf.h
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26 * This file is a GNU extension to the Standard C++ Library.
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27 */
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28
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29 #ifndef _STDIO_FILEBUF_H
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30 #define _STDIO_FILEBUF_H 1
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31
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32 #pragma GCC system_header
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33
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34 #include <fstream>
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35
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36 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
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37 {
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38 _GLIBCXX_BEGIN_NAMESPACE_VERSION
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39
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40 /**
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41 * @brief Provides a layer of compatibility for C/POSIX.
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42 * @ingroup io
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43 *
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44 * This GNU extension provides extensions for working with standard C
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45 * FILE*'s and POSIX file descriptors. It must be instantiated by the
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46 * user with the type of character used in the file stream, e.g.,
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47 * stdio_filebuf<char>.
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48 */
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49 template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
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50 class stdio_filebuf : public std::basic_filebuf<_CharT, _Traits>
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51 {
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52 public:
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53 // Types:
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54 typedef _CharT char_type;
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55 typedef _Traits traits_type;
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56 typedef typename traits_type::int_type int_type;
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57 typedef typename traits_type::pos_type pos_type;
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58 typedef typename traits_type::off_type off_type;
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59 typedef std::size_t size_t;
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60
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61 public:
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62 /**
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63 * deferred initialization
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64 */
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65 stdio_filebuf() : std::basic_filebuf<_CharT, _Traits>() {}
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66
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67 /**
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68 * @param __fd An open file descriptor.
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69 * @param __mode Same meaning as in a standard filebuf.
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70 * @param __size Optimal or preferred size of internal buffer,
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71 * in chars.
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72 *
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73 * This constructor associates a file stream buffer with an open
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74 * POSIX file descriptor. The file descriptor will be automatically
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75 * closed when the stdio_filebuf is closed/destroyed.
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76 */
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77 stdio_filebuf(int __fd, std::ios_base::openmode __mode,
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78 size_t __size = static_cast<size_t>(BUFSIZ));
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79
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80 /**
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81 * @param __f An open @c FILE*.
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82 * @param __mode Same meaning as in a standard filebuf.
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83 * @param __size Optimal or preferred size of internal buffer,
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84 * in chars. Defaults to system's @c BUFSIZ.
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85 *
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86 * This constructor associates a file stream buffer with an open
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87 * C @c FILE*. The @c FILE* will not be automatically closed when the
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88 * stdio_filebuf is closed/destroyed.
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89 */
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90 stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
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91 size_t __size = static_cast<size_t>(BUFSIZ));
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92
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93 /**
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94 * Closes the external data stream if the file descriptor constructor
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95 * was used.
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96 */
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97 virtual
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98 ~stdio_filebuf();
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99
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100 #if __cplusplus >= 201103L
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101 stdio_filebuf(stdio_filebuf&&) = default;
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102 stdio_filebuf& operator=(stdio_filebuf&&) = default;
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103
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104 void
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105 swap(stdio_filebuf& __fb)
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106 { std::basic_filebuf<_CharT, _Traits>::swap(__fb); }
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107 #endif
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108
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109 /**
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110 * @return The underlying file descriptor.
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111 *
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112 * Once associated with an external data stream, this function can be
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113 * used to access the underlying POSIX file descriptor. Note that
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114 * there is no way for the library to track what you do with the
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115 * descriptor, so be careful.
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116 */
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117 int
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118 fd() { return this->_M_file.fd(); }
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119
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120 /**
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121 * @return The underlying FILE*.
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122 *
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123 * This function can be used to access the underlying "C" file pointer.
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124 * Note that there is no way for the library to track what you do
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125 * with the file, so be careful.
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126 */
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127 std::__c_file*
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128 file() { return this->_M_file.file(); }
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129 };
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130
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131 template<typename _CharT, typename _Traits>
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132 stdio_filebuf<_CharT, _Traits>::~stdio_filebuf()
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133 { }
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134
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135 template<typename _CharT, typename _Traits>
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136 stdio_filebuf<_CharT, _Traits>::
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137 stdio_filebuf(int __fd, std::ios_base::openmode __mode, size_t __size)
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138 {
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139 this->_M_file.sys_open(__fd, __mode);
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140 if (this->is_open())
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141 {
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142 this->_M_mode = __mode;
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143 this->_M_buf_size = __size;
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144 this->_M_allocate_internal_buffer();
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145 this->_M_reading = false;
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146 this->_M_writing = false;
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147 this->_M_set_buffer(-1);
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148 }
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149 }
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150
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151 template<typename _CharT, typename _Traits>
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152 stdio_filebuf<_CharT, _Traits>::
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153 stdio_filebuf(std::__c_file* __f, std::ios_base::openmode __mode,
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154 size_t __size)
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155 {
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156 this->_M_file.sys_open(__f, __mode);
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157 if (this->is_open())
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158 {
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159 this->_M_mode = __mode;
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160 this->_M_buf_size = __size;
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161 this->_M_allocate_internal_buffer();
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162 this->_M_reading = false;
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163 this->_M_writing = false;
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164 this->_M_set_buffer(-1);
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165 }
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166 }
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167
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168 _GLIBCXX_END_NAMESPACE_VERSION
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169 } // namespace
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170
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171 #endif
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