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

// Wrapper of C-language FILE struct -*- C++ -*-

// Copyright (C) 1999, 2000, 2001 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 2, 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.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

//
// ISO C++ 14882: 27.8  File-based streams
//

/** @file basic_file.h
 *  This is an internal header file, included by other library headers.
 *  You should not attempt to use it directly.
 */

#ifndef _CPP_BASIC_FILE
#define _CPP_BASIC_FILE		1

#pragma GCC system_header

#include <bits/c++config.h>
#include <bits/std_ios.h>

namespace std 
{
  // Ulrich is going to make some detailed comment here, explaining
  // all this unpleasantness, providing detailed performance analysis
  // as to why we have to do all this lame vtable hacking instead of a
  // sane, function-based approach. This verbiage will provide a clear
  // and detailed description of the whole object-layout,
  // vtable-swapping, sordid history of this hack.
  template<typename _CharT>
    struct __basic_file_base: public __c_file_type
    {
      virtual 
      ~__basic_file_base() { };

      virtual int 
      overflow(int __c = EOF) = 0;

      virtual int 
      underflow() = 0;

      virtual int 
      uflow() = 0;

      virtual int 
      pbackfail(int __c) = 0;

      virtual streamsize 
      xsputn(const _CharT* __s, streamsize __n) = 0;

      virtual streamsize 
      xsgetn(_CharT* __s, streamsize __n) = 0;

      virtual streamoff
      seekoff(streamoff __off, ios_base::seekdir __way,
	      ios_base::openmode __mode = ios_base::in | ios_base::out) = 0;

      virtual streamoff
      seekpos(streamoff __pos, 
	      ios_base::openmode __mode = ios_base::in | ios_base::out) = 0;

      virtual streambuf* 
      setbuf(_CharT* __b, int __len) = 0;

      virtual int 
      sync() = 0;

      virtual int 
      doallocate() = 0;

      virtual streamsize 
      sys_read(_CharT* __s, streamsize __n) = 0;

      virtual streamsize 
      sys_write(const _CharT* __s, streamsize __n) = 0;

      virtual streamoff
      sys_seek(streamoff __off, ios_base::seekdir __way) = 0;

      virtual int 
      sys_close() = 0;

      virtual int 
      sys_stat(void* __v) = 0;

      virtual int 
      showmanyc() = 0;

      virtual void 
      imbue(void* __v) = 0;
    };

  // Some of these member functions are based on libio/filebuf.cc.
  // Also note that the order and number of virtual functions has to precisely
  // match the order and number in the _IO_jump_t struct defined in libioP.h.
  template<typename _CharT>
#ifdef _GLIBCPP_BASIC_FILE_INHERITANCE
    class __basic_file: public __basic_file_base<_CharT>
#else
    class __basic_file
#endif
    {
#if _GLIBCPP_BASIC_FILE_ENCAPSULATION
      // underlying data source/sink
      __c_file_type* 	_M_cfile;
      // true iff we opened _M_cfile, and thus must close it ourselves
      bool 		_M_cfile_created;
#else
# ifdef _GLIBCPP_USE_WCHAR_T
      __c_wfile_type	_M_wfile;
# endif
#endif 

    public:
      __basic_file(__c_lock* __lock = 0);
      
      void 
      _M_open_mode(ios_base::openmode __mode, int& __p_mode, int& __rw_mode, 
		   char* __c_mode);
      
      // Equivalent to the normal fopen function.
      __basic_file* 
      open(const char* __name, ios_base::openmode __mode, int __prot = 0664);

      // Used for opening the standard streams, cin, cout, cerr, clog,
      // and their wide-stream equivalents. Instead of calling open, it
      // just sets
      //  - for libio:  __c_file_type->_fileno and the respective _flags bits
      //  - for stdio:  _M_cfile = __file and some internal flags
      // and returns.
      __basic_file*
      sys_open(__c_file_type* __file, ios_base::openmode __mode);

      _CharT
      sys_getc();

      _CharT
      sys_ungetc(_CharT);

      __basic_file* 
      close(); 

      bool 
      is_open();

      int 
      fd();

      // NB: Must match FILE specific jump table starting here--this
      // means all virtual functions starting with the dtor must match,
      // slot by slot. For glibc-based dystems, this means the _IO_FILE
      // as the FILE struct and _IO_jump_t as the jump table.
      virtual 
      ~__basic_file(); // Takes the place of __finish.

      virtual int 
      overflow(int __c = EOF);

      virtual int 
      underflow();

      virtual int 
      uflow();

      virtual int 
      pbackfail(int __c);

      // A complex "write" function that sets all of __c_file_type's
      // pointers and associated data members correctly and manages its
      // relation to the external byte sequence.
      virtual streamsize 
      xsputn(const _CharT* __s, streamsize __n);

      // A complex "read" function that sets all of __c_file_type's
      // pointers and associated data members correctly and manages its
      // relation to the external byte sequence.
      virtual streamsize 
      xsgetn(_CharT* __s, streamsize __n);

      // A complex "seekoff" function that sets all of __c_file_type's
      // pointers and associated data members correctly and manages its
      // relation to the external byte sequence.
      virtual streamoff
      seekoff(streamoff __off, ios_base::seekdir __way,
	      ios_base::openmode __mode = ios_base::in | ios_base::out);

      // A complex "seekpos" function that sets all of __c_file_type's
      // pointers and associated data members correctly and manages its
      // relation to the external byte sequence.
      virtual streamoff
      seekpos(streamoff __pos, 
	      ios_base::openmode __mode = ios_base::in | ios_base::out);

      virtual streambuf* 
      setbuf(_CharT* __b, int __len);

      virtual int 
      sync();

      virtual int 
      doallocate();

      // A simple read function for the external byte sequence, that
      // does no mucking around with or setting of the pointers or flags
      // in __c_file_type.
      virtual streamsize 
      sys_read(_CharT* __s, streamsize __n);

      // A simple write function for the external byte sequence, that
      // does no mucking around with or setting of the pointers or flags
      // in __c_file_type.
      virtual streamsize 
      sys_write(const _CharT* __s, streamsize __n);

      // A simple seek function for the external byte sequence, that
      // does no mucking around with or setting of the pointers or flags
      // in __c_file_type.
      virtual streamoff
      sys_seek(streamoff __off, ios_base::seekdir __way);

      virtual int 
      sys_close();

      virtual int 
      sys_stat(void* __v);

      virtual int 
      showmanyc();

      virtual void 
      imbue(void* __v);
    };
} // namespace std

// Now include the bits that are dependent on the underlying I/O
// model chosen at configure time.
#include <bits/basic_file_model.h>

#endif	// _CPP_BASIC_FILE