libstdc++-v3/include/bits/basic_file.h

   1 // Wrapper of C-language FILE struct -*- C++ -*-
   2
   3 // Copyright (C) 1999, 2000, 2001 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 2, 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 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 //
  31 // ISO C++ 14882: 27.8  File-based streams
  32 //
  33
  34 /** @file basic_file.h
  35  *  This is an internal header file, included by other library headers.
  36  *  You should not attempt to use it directly.
  37  */
  38
  39 #ifndef _CPP_BASIC_FILE
  40 #define _CPP_BASIC_FILE         1
  41
  42 #pragma GCC system_header
  43
  44 #include <bits/c++config.h>
  45 #include <ios>
  46
  47 namespace std
  48 {
  49   // Ulrich is going to make some detailed comment here, explaining
  50   // all this unpleasantness, providing detailed performance analysis
  51   // as to why we have to do all this lame vtable hacking instead of a
  52   // sane, function-based approach. This verbiage will provide a clear
  53   // and detailed description of the whole object-layout,
  54   // vtable-swapping, sordid history of this hack.
  55   template<typename _CharT>
  56     struct __basic_file_base: public __c_file_type
  57     {
  58       virtual
  59       ~__basic_file_base() { };
  60
  61       virtual int
  62       overflow(int __c = EOF) = 0;
  63
  64       virtual int
  65       underflow() = 0;
  66
  67       virtual int
  68       uflow() = 0;
  69
  70       virtual int
  71       pbackfail(int __c) = 0;
  72
  73       virtual streamsize
  74       xsputn(const _CharT* __s, streamsize __n) = 0;
  75
  76       virtual streamsize
  77       xsgetn(_CharT* __s, streamsize __n) = 0;
  78
  79       virtual streamoff
  80       seekoff(streamoff __off, ios_base::seekdir __way,
  81               ios_base::openmode __mode = ios_base::in | ios_base::out) = 0;
  82
  83       virtual streamoff
  84       seekpos(streamoff __pos,
  85               ios_base::openmode __mode = ios_base::in | ios_base::out) = 0;
  86
  87       virtual streambuf*
  88       setbuf(_CharT* __b, int __len) = 0;
  89
  90       virtual int
  91       sync() = 0;
  92
  93       virtual int
  94       doallocate() = 0;
  95
  96       virtual streamsize
  97       sys_read(_CharT* __s, streamsize __n) = 0;
  98
  99       virtual streamsize
 100       sys_write(const _CharT* __s, streamsize __n) = 0;
 101
 102       virtual streamoff
 103       sys_seek(streamoff __off, ios_base::seekdir __way) = 0;
 104
 105       virtual int
 106       sys_close() = 0;
 107
 108       virtual int
 109       sys_stat(void* __v) = 0;
 110
 111       virtual int
 112       showmanyc() = 0;
 113
 114       virtual void
 115       imbue(void* __v) = 0;
 116     };
 117
 118   // Some of these member functions are based on libio/filebuf.cc.
 119   // Also note that the order and number of virtual functions has to precisely
 120   // match the order and number in the _IO_jump_t struct defined in libioP.h.
 121   template<typename _CharT>
 122 #ifdef _GLIBCPP_BASIC_FILE_INHERITANCE
 123     class __basic_file: public __basic_file_base<_CharT>
 124 #else
 125     class __basic_file
 126 #endif
 127     {
 128 #if _GLIBCPP_BASIC_FILE_ENCAPSULATION
 129       // underlying data source/sink
 130       __c_file_type*    _M_cfile;
 131       // true iff we opened _M_cfile, and thus must close it ourselves
 132       bool              _M_cfile_created;
 133 #else
 134 # ifdef _GLIBCPP_USE_WCHAR_T
 135       __c_wfile_type    _M_wfile;
 136 # endif
 137 #endif
 138
 139     public:
 140       __basic_file(__c_lock* __lock = 0);
 141
 142       void
 143       _M_open_mode(ios_base::openmode __mode, int& __p_mode, int& __rw_mode,
 144                    char* __c_mode);
 145
 146       // Equivalent to the normal fopen function.
 147       __basic_file*
 148       open(const char* __name, ios_base::openmode __mode, int __prot = 0664);
 149
 150       // Used for opening the standard streams, cin, cout, cerr, clog,
 151       // and their wide-stream equivalents. Instead of calling open, it
 152       // just sets
 153       //  - for libio:  __c_file_type->_fileno and the respective _flags bits
 154       //  - for stdio:  _M_cfile = __file and some internal flags
 155       // and returns.
 156       __basic_file*
 157       sys_open(__c_file_type* __file, ios_base::openmode __mode);
 158
 159       _CharT
 160       sys_getc();
 161
 162       _CharT
 163       sys_ungetc(_CharT);
 164
 165       __basic_file*
 166       close();
 167
 168       bool
 169       is_open();
 170
 171       int
 172       fd();
 173
 174       // NB: Must match FILE specific jump table starting here--this
 175       // means all virtual functions starting with the dtor must match,
 176       // slot by slot. For glibc-based dystems, this means the _IO_FILE
 177       // as the FILE struct and _IO_jump_t as the jump table.
 178       virtual
 179       ~__basic_file(); // Takes the place of __finish.
 180
 181       virtual int
 182       overflow(int __c = EOF);
 183
 184       virtual int
 185       underflow();
 186
 187       virtual int
 188       uflow();
 189
 190       virtual int
 191       pbackfail(int __c);
 192
 193       // A complex "write" function that sets all of __c_file_type's
 194       // pointers and associated data members correctly and manages its
 195       // relation to the external byte sequence.
 196       virtual streamsize
 197       xsputn(const _CharT* __s, streamsize __n);
 198
 199       // A complex "read" function that sets all of __c_file_type's
 200       // pointers and associated data members correctly and manages its
 201       // relation to the external byte sequence.
 202       virtual streamsize
 203       xsgetn(_CharT* __s, streamsize __n);
 204
 205       // A complex "seekoff" function that sets all of __c_file_type's
 206       // pointers and associated data members correctly and manages its
 207       // relation to the external byte sequence.
 208       virtual streamoff
 209       seekoff(streamoff __off, ios_base::seekdir __way,
 210               ios_base::openmode __mode = ios_base::in | ios_base::out);
 211
 212       // A complex "seekpos" function that sets all of __c_file_type's
 213       // pointers and associated data members correctly and manages its
 214       // relation to the external byte sequence.
 215       virtual streamoff
 216       seekpos(streamoff __pos,
 217               ios_base::openmode __mode = ios_base::in | ios_base::out);
 218
 219       virtual streambuf*
 220       setbuf(_CharT* __b, int __len);
 221
 222       virtual int
 223       sync();
 224
 225       virtual int
 226       doallocate();
 227
 228       // A simple read function for the external byte sequence, that
 229       // does no mucking around with or setting of the pointers or flags
 230       // in __c_file_type.
 231       virtual streamsize
 232       sys_read(_CharT* __s, streamsize __n);
 233
 234       // A simple write function for the external byte sequence, that
 235       // does no mucking around with or setting of the pointers or flags
 236       // in __c_file_type.
 237       virtual streamsize
 238       sys_write(const _CharT* __s, streamsize __n);
 239
 240       // A simple seek function for the external byte sequence, that
 241       // does no mucking around with or setting of the pointers or flags
 242       // in __c_file_type.
 243       virtual streamoff
 244       sys_seek(streamoff __off, ios_base::seekdir __way);
 245
 246       virtual int
 247       sys_close();
 248
 249       virtual int
 250       sys_stat(void* __v);
 251
 252       virtual int
 253       showmanyc();
 254
 255       virtual void
 256       imbue(void* __v);
 257     };
 258 } // namespace std
 259
 260 // Now include the bits that are dependent on the underlying I/O
 261 // model chosen at configure time.
 262 #include <bits/basic_file_model.h>
 263
 264 #endif  // _CPP_BASIC_FILE