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ec01f29236
gcc/libstdc++-v3/include/std/fstream
Paolo Carlini ec01f29236 basic_file_stdio.cc (fopen_mode): Add modes missing per DR 596. 
2007-11-08  Paolo Carlini  <pcarlini@suse.de>

	* config/io/basic_file_stdio.cc (fopen_mode): Add modes missing
	per DR 596.
	* testsuite/27_io/basic_filebuf/open/char/4.cc: Extend.
	* include/std/fstream: Update comment preceding open.
	* docs/html/ext/howto.html: Update.

From-SVN: r130004
2007-11-08 16:22:21 +00:00

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// File based streams -*- C++ -*-
// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
// 2006, 2007
// 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, 51 Franklin Street, Fifth Floor,
// Boston, MA 02110-1301, 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.
/** @file fstream
* This is a Standard C++ Library header.
*/
//
// ISO C++ 14882: 27.8 File-based streams
//
#ifndef _GLIBCXX_FSTREAM
#define _GLIBCXX_FSTREAM 1
#pragma GCC system_header
#include <istream>
#include <ostream>
#include <bits/codecvt.h>
#include <cstdio> // For BUFSIZ
#include <bits/basic_file.h> // For __basic_file, __c_lock
_GLIBCXX_BEGIN_NAMESPACE(std)
// [27.8.1.1] template class basic_filebuf
/**
* @brief The actual work of input and output (for files).
*
* This class associates both its input and output sequence with an
* external disk file, and maintains a joint file position for both
* sequences. Many of its sematics are described in terms of similar
* behavior in the Standard C Library's @c FILE streams.
*/
// Requirements on traits_type, specific to this class:
// traits_type::pos_type must be fpos<traits_type::state_type>
// traits_type::off_type must be streamoff
// traits_type::state_type must be Assignable and DefaultConstructible,
// and traits_type::state_type() must be the initial state for codecvt.
template<typename _CharT, typename _Traits>
class basic_filebuf : public basic_streambuf<_CharT, _Traits>
{
public:
// Types:
typedef _CharT char_type;
typedef _Traits traits_type;
typedef typename traits_type::int_type int_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
typedef basic_streambuf<char_type, traits_type> __streambuf_type;
typedef basic_filebuf<char_type, traits_type> __filebuf_type;
typedef __basic_file<char> __file_type;
typedef typename traits_type::state_type __state_type;
typedef codecvt<char_type, char, __state_type> __codecvt_type;
friend class ios_base; // For sync_with_stdio.
protected:
// Data Members:
// MT lock inherited from libio or other low-level io library.
__c_lock _M_lock;
// External buffer.
__file_type _M_file;
/**
* @if maint
* Place to stash in || out || in | out settings for current filebuf.
* @endif
*/
ios_base::openmode _M_mode;
// Beginning state type for codecvt.
__state_type _M_state_beg;
// During output, the state that corresponds to pptr(),
// during input, the state that corresponds to egptr() and
// _M_ext_next.
__state_type _M_state_cur;
// Not used for output. During input, the state that corresponds
// to eback() and _M_ext_buf.
__state_type _M_state_last;
/**
* @if maint
* Pointer to the beginning of internal buffer.
* @endif
*/
char_type* _M_buf;
/**
* @if maint
* Actual size of internal buffer. This number is equal to the size
* of the put area + 1 position, reserved for the overflow char of
* a full area.
* @endif
*/
size_t _M_buf_size;
// Set iff _M_buf is allocated memory from _M_allocate_internal_buffer.
bool _M_buf_allocated;
/**
* @if maint
* _M_reading == false && _M_writing == false for 'uncommitted' mode;
* _M_reading == true for 'read' mode;
* _M_writing == true for 'write' mode;
*
* NB: _M_reading == true && _M_writing == true is unused.
* @endif
*/
bool _M_reading;
bool _M_writing;
//@{
/**
* @if maint
* Necessary bits for putback buffer management.
*
* @note pbacks of over one character are not currently supported.
* @endif
*/
char_type _M_pback;
char_type* _M_pback_cur_save;
char_type* _M_pback_end_save;
bool _M_pback_init;
//@}
// Cached codecvt facet.
const __codecvt_type* _M_codecvt;
/**
* @if maint
* Buffer for external characters. Used for input when
* codecvt::always_noconv() == false. When valid, this corresponds
* to eback().
* @endif
*/
char* _M_ext_buf;
/**
* @if maint
* Size of buffer held by _M_ext_buf.
* @endif
*/
streamsize _M_ext_buf_size;
/**
* @if maint
* Pointers into the buffer held by _M_ext_buf that delimit a
* subsequence of bytes that have been read but not yet converted.
* When valid, _M_ext_next corresponds to egptr().
* @endif
*/
const char* _M_ext_next;
char* _M_ext_end;
/**
* @if maint
* Initializes pback buffers, and moves normal buffers to safety.
* Assumptions:
* _M_in_cur has already been moved back
* @endif
*/
void
_M_create_pback()
{
if (!_M_pback_init)
{
_M_pback_cur_save = this->gptr();
_M_pback_end_save = this->egptr();
this->setg(&_M_pback, &_M_pback, &_M_pback + 1);
_M_pback_init = true;
}
}
/**
* @if maint
* Deactivates pback buffer contents, and restores normal buffer.
* Assumptions:
* The pback buffer has only moved forward.
* @endif
*/
void
_M_destroy_pback() throw()
{
if (_M_pback_init)
{
// Length _M_in_cur moved in the pback buffer.
_M_pback_cur_save += this->gptr() != this->eback();
this->setg(_M_buf, _M_pback_cur_save, _M_pback_end_save);
_M_pback_init = false;
}
}
public:
// Constructors/destructor:
/**
* @brief Does not open any files.
*
* The default constructor initializes the parent class using its
* own default ctor.
*/
basic_filebuf();
/**
* @brief The destructor closes the file first.
*/
virtual
~basic_filebuf()
{ this->close(); }
// Members:
/**
* @brief Returns true if the external file is open.
*/
bool
is_open() const throw()
{ return _M_file.is_open(); }
/**
* @brief Opens an external file.
* @param s The name of the file.
* @param mode The open mode flags.
* @return @c this on success, NULL on failure
*
* If a file is already open, this function immediately fails.
* Otherwise it tries to open the file named @a s using the flags
* given in @a mode.
*
* Table 92, adapted here, gives the relation between openmode
* combinations and the equivalent fopen() flags.
* (NB: lines app, in|out|app, in|app, binary|app, binary|in|out|app,
* and binary|in|app per DR 596)
* +---------------------------------------------------------+
* | ios_base Flag combination stdio equivalent |
* |binary in out trunc app |
* +---------------------------------------------------------+
* | + "w" |
* | + + "a" |
* | + "a" |
* | + + "w" |
* | + "r" |
* | + + "r+" |
* | + + + "w+" |
* | + + + "a+" |
* | + + "a+" |
* +---------------------------------------------------------+
* | + + "wb" |
* | + + + "ab" |
* | + + "ab" |
* | + + + "wb" |
* | + + "rb" |
* | + + + "r+b" |
* | + + + + "w+b" |
* | + + + + "a+b" |
* | + + + "a+b" |
* +---------------------------------------------------------+
*/
__filebuf_type*
open(const char* __s, ios_base::openmode __mode);
/**
* @brief Closes the currently associated file.
* @return @c this on success, NULL on failure
*
* If no file is currently open, this function immediately fails.
*
* If a "put buffer area" exists, @c overflow(eof) is called to flush
* all the characters. The file is then closed.
*
* If any operations fail, this function also fails.
*/
__filebuf_type*
close();
protected:
void
_M_allocate_internal_buffer();
void
_M_destroy_internal_buffer() throw();
// [27.8.1.4] overridden virtual functions
virtual streamsize
showmanyc();
// Stroustrup, 1998, p. 628
// underflow() and uflow() functions are called to get the next
// charater from the real input source when the buffer is empty.
// Buffered input uses underflow()
virtual int_type
underflow();
virtual int_type
pbackfail(int_type __c = _Traits::eof());
// Stroustrup, 1998, p 648
// The overflow() function is called to transfer characters to the
// real output destination when the buffer is full. A call to
// overflow(c) outputs the contents of the buffer plus the
// character c.
// 27.5.2.4.5
// Consume some sequence of the characters in the pending sequence.
virtual int_type
overflow(int_type __c = _Traits::eof());
// Convert internal byte sequence to external, char-based
// sequence via codecvt.
bool
_M_convert_to_external(char_type*, streamsize);
/**
* @brief Manipulates the buffer.
* @param s Pointer to a buffer area.
* @param n Size of @a s.
* @return @c this
*
* If no file has been opened, and both @a s and @a n are zero, then
* the stream becomes unbuffered. Otherwise, @c s is used as a
* buffer; see
* http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2
* for more.
*/
virtual __streambuf_type*
setbuf(char_type* __s, streamsize __n);
virtual pos_type
seekoff(off_type __off, ios_base::seekdir __way,
ios_base::openmode __mode = ios_base::in | ios_base::out);
virtual pos_type
seekpos(pos_type __pos,
ios_base::openmode __mode = ios_base::in | ios_base::out);
// Common code for seekoff and seekpos
pos_type
_M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);
virtual int
sync();
virtual void
imbue(const locale& __loc);
virtual streamsize
xsgetn(char_type* __s, streamsize __n);
virtual streamsize
xsputn(const char_type* __s, streamsize __n);
// Flushes output buffer, then writes unshift sequence.
bool
_M_terminate_output();
/**
* @if maint
* This function sets the pointers of the internal buffer, both get
* and put areas. Typically:
*
* __off == egptr() - eback() upon underflow/uflow ('read' mode);
* __off == 0 upon overflow ('write' mode);
* __off == -1 upon open, setbuf, seekoff/pos ('uncommitted' mode).
*
* NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size
* reflects the actual allocated memory and the last cell is reserved
* for the overflow char of a full put area.
* @endif
*/
void
_M_set_buffer(streamsize __off)
{
const bool __testin = _M_mode & ios_base::in;
const bool __testout = _M_mode & ios_base::out;
if (__testin && __off > 0)
this->setg(_M_buf, _M_buf, _M_buf + __off);
else
this->setg(_M_buf, _M_buf, _M_buf);
if (__testout && __off == 0 && _M_buf_size > 1 )
this->setp(_M_buf, _M_buf + _M_buf_size - 1);
else
this->setp(NULL, NULL);
}
};
// [27.8.1.5] Template class basic_ifstream
/**
* @brief Controlling input for files.
*
* This class supports reading from named files, using the inherited
* functions from std::basic_istream. To control the associated
* sequence, an instance of std::basic_filebuf is used, which this page
* refers to as @c sb.
*/
template<typename _CharT, typename _Traits>
class basic_ifstream : public basic_istream<_CharT, _Traits>
{
public:
// Types:
typedef _CharT char_type;
typedef _Traits traits_type;
typedef typename traits_type::int_type int_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
// Non-standard types:
typedef basic_filebuf<char_type, traits_type> __filebuf_type;
typedef basic_istream<char_type, traits_type> __istream_type;
private:
__filebuf_type _M_filebuf;
public:
// Constructors/Destructors:
/**
* @brief Default constructor.
*
* Initializes @c sb using its default constructor, and passes
* @c &sb to the base class initializer. Does not open any files
* (you haven't given it a filename to open).
*/
basic_ifstream() : __istream_type(), _M_filebuf()
{ this->init(&_M_filebuf); }
/**
* @brief Create an input file stream.
* @param s Null terminated string specifying the filename.
* @param mode Open file in specified mode (see std::ios_base).
*
* @c ios_base::in is automatically included in @a mode.
*
* Tip: When using std::string to hold the filename, you must use
* .c_str() before passing it to this constructor.
*/
explicit
basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
: __istream_type(), _M_filebuf()
{
this->init(&_M_filebuf);
this->open(__s, __mode);
}
/**
* @brief The destructor does nothing.
*
* The file is closed by the filebuf object, not the formatting
* stream.
*/
~basic_ifstream()
{ }
// Members:
/**
* @brief Accessing the underlying buffer.
* @return The current basic_filebuf buffer.
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
__filebuf_type*
rdbuf() const
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
/**
* @brief Wrapper to test for an open file.
* @return @c rdbuf()->is_open()
*/
bool
is_open()
{ return _M_filebuf.is_open(); }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 365. Lack of const-qualification in clause 27
bool
is_open() const
{ return _M_filebuf.is_open(); }
/**
* @brief Opens an external file.
* @param s The name of the file.
* @param mode The open mode flags.
*
* Calls @c std::basic_filebuf::open(s,mode|in). If that function
* fails, @c failbit is set in the stream's error state.
*
* Tip: When using std::string to hold the filename, you must use
* .c_str() before passing it to this constructor.
*/
void
open(const char* __s, ios_base::openmode __mode = ios_base::in)
{
if (!_M_filebuf.open(__s, __mode | ios_base::in))
this->setstate(ios_base::failbit);
else
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 409. Closing an fstream should clear error state
this->clear();
}
/**
* @brief Close the file.
*
* Calls @c std::basic_filebuf::close(). If that function
* fails, @c failbit is set in the stream's error state.
*/
void
close()
{
if (!_M_filebuf.close())
this->setstate(ios_base::failbit);
}
};
// [27.8.1.8] Template class basic_ofstream
/**
* @brief Controlling output for files.
*
* This class supports reading from named files, using the inherited
* functions from std::basic_ostream. To control the associated
* sequence, an instance of std::basic_filebuf is used, which this page
* refers to as @c sb.
*/
template<typename _CharT, typename _Traits>
class basic_ofstream : public basic_ostream<_CharT,_Traits>
{
public:
// Types:
typedef _CharT char_type;
typedef _Traits traits_type;
typedef typename traits_type::int_type int_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
// Non-standard types:
typedef basic_filebuf<char_type, traits_type> __filebuf_type;
typedef basic_ostream<char_type, traits_type> __ostream_type;
private:
__filebuf_type _M_filebuf;
public:
// Constructors:
/**
* @brief Default constructor.
*
* Initializes @c sb using its default constructor, and passes
* @c &sb to the base class initializer. Does not open any files
* (you haven't given it a filename to open).
*/
basic_ofstream(): __ostream_type(), _M_filebuf()
{ this->init(&_M_filebuf); }
/**
* @brief Create an output file stream.
* @param s Null terminated string specifying the filename.
* @param mode Open file in specified mode (see std::ios_base).
*
* @c ios_base::out|ios_base::trunc is automatically included in
* @a mode.
*
* Tip: When using std::string to hold the filename, you must use
* .c_str() before passing it to this constructor.
*/
explicit
basic_ofstream(const char* __s,
ios_base::openmode __mode = ios_base::out|ios_base::trunc)
: __ostream_type(), _M_filebuf()
{
this->init(&_M_filebuf);
this->open(__s, __mode);
}
/**
* @brief The destructor does nothing.
*
* The file is closed by the filebuf object, not the formatting
* stream.
*/
~basic_ofstream()
{ }
// Members:
/**
* @brief Accessing the underlying buffer.
* @return The current basic_filebuf buffer.
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
__filebuf_type*
rdbuf() const
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
/**
* @brief Wrapper to test for an open file.
* @return @c rdbuf()->is_open()
*/
bool
is_open()
{ return _M_filebuf.is_open(); }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 365. Lack of const-qualification in clause 27
bool
is_open() const
{ return _M_filebuf.is_open(); }
/**
* @brief Opens an external file.
* @param s The name of the file.
* @param mode The open mode flags.
*
* Calls @c std::basic_filebuf::open(s,mode|out|trunc). If that
* function fails, @c failbit is set in the stream's error state.
*
* Tip: When using std::string to hold the filename, you must use
* .c_str() before passing it to this constructor.
*/
void
open(const char* __s,
ios_base::openmode __mode = ios_base::out | ios_base::trunc)
{
if (!_M_filebuf.open(__s, __mode | ios_base::out))
this->setstate(ios_base::failbit);
else
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 409. Closing an fstream should clear error state
this->clear();
}
/**
* @brief Close the file.
*
* Calls @c std::basic_filebuf::close(). If that function
* fails, @c failbit is set in the stream's error state.
*/
void
close()
{
if (!_M_filebuf.close())
this->setstate(ios_base::failbit);
}
};
// [27.8.1.11] Template class basic_fstream
/**
* @brief Controlling intput and output for files.
*
* This class supports reading from and writing to named files, using
* the inherited functions from std::basic_iostream. To control the
* associated sequence, an instance of std::basic_filebuf is used, which
* this page refers to as @c sb.
*/
template<typename _CharT, typename _Traits>
class basic_fstream : public basic_iostream<_CharT, _Traits>
{
public:
// Types:
typedef _CharT char_type;
typedef _Traits traits_type;
typedef typename traits_type::int_type int_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
// Non-standard types:
typedef basic_filebuf<char_type, traits_type> __filebuf_type;
typedef basic_ios<char_type, traits_type> __ios_type;
typedef basic_iostream<char_type, traits_type> __iostream_type;
private:
__filebuf_type _M_filebuf;
public:
// Constructors/destructor:
/**
* @brief Default constructor.
*
* Initializes @c sb using its default constructor, and passes
* @c &sb to the base class initializer. Does not open any files
* (you haven't given it a filename to open).
*/
basic_fstream()
: __iostream_type(), _M_filebuf()
{ this->init(&_M_filebuf); }
/**
* @brief Create an input/output file stream.
* @param s Null terminated string specifying the filename.
* @param mode Open file in specified mode (see std::ios_base).
*
* Tip: When using std::string to hold the filename, you must use
* .c_str() before passing it to this constructor.
*/
explicit
basic_fstream(const char* __s,
ios_base::openmode __mode = ios_base::in | ios_base::out)
: __iostream_type(NULL), _M_filebuf()
{
this->init(&_M_filebuf);
this->open(__s, __mode);
}
/**
* @brief The destructor does nothing.
*
* The file is closed by the filebuf object, not the formatting
* stream.
*/
~basic_fstream()
{ }
// Members:
/**
* @brief Accessing the underlying buffer.
* @return The current basic_filebuf buffer.
*
* This hides both signatures of std::basic_ios::rdbuf().
*/
__filebuf_type*
rdbuf() const
{ return const_cast<__filebuf_type*>(&_M_filebuf); }
/**
* @brief Wrapper to test for an open file.
* @return @c rdbuf()->is_open()
*/
bool
is_open()
{ return _M_filebuf.is_open(); }
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 365. Lack of const-qualification in clause 27
bool
is_open() const
{ return _M_filebuf.is_open(); }
/**
* @brief Opens an external file.
* @param s The name of the file.
* @param mode The open mode flags.
*
* Calls @c std::basic_filebuf::open(s,mode). If that
* function fails, @c failbit is set in the stream's error state.
*
* Tip: When using std::string to hold the filename, you must use
* .c_str() before passing it to this constructor.
*/
void
open(const char* __s,
ios_base::openmode __mode = ios_base::in | ios_base::out)
{
if (!_M_filebuf.open(__s, __mode))
this->setstate(ios_base::failbit);
else
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 409. Closing an fstream should clear error state
this->clear();
}
/**
* @brief Close the file.
*
* Calls @c std::basic_filebuf::close(). If that function
* fails, @c failbit is set in the stream's error state.
*/
void
close()
{
if (!_M_filebuf.close())
this->setstate(ios_base::failbit);
}
};
_GLIBCXX_END_NAMESPACE
#ifndef _GLIBCXX_EXPORT_TEMPLATE
# include <bits/fstream.tcc>
#endif
#endif /* _GLIBCXX_FSTREAM */
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