__gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >(3)

NAME
__gnu_cxx::stdio_sync_filebuf< _CharT, _Traits > - Provides a layer of compatibility for C.

SYNOPSIS

Inherits std::basic_streambuf< _CharT, std::char_traits< _CharT > >.

  Public Types
typedef _CharT char_type
typedef traits_type::int_type int_type
typedef traits_type::off_type off_type
typedef traits_type::pos_type pos_type
typedef _Traits traits_type

  Public Member Functions
stdio_sync_filebuf (std::__c_file *__f)
stdio_sync_filebuf (stdio_sync_filebuf &&__fb) noexcept
std::__c_file * file ()
locale getloc () const
Locale access.
streamsize in_avail ()
Looking ahead into the stream.
stdio_sync_filebuf & operator= (stdio_sync_filebuf &&__fb) noexcept
locale pubimbue (const locale &__loc)
Entry point for imbue().
pos_type pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream position.
pos_type pubseekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream position.
basic_streambuf * pubsetbuf (char_type *__s, streamsize __n)
Entry points for derived buffer functions.
int pubsync ()
Calls virtual sync function.
int_type sbumpc ()
Getting the next character.
int_type sgetc ()
Getting the next character.
streamsize sgetn (char_type *__s, streamsize __n)
Entry point for xsgetn.
int_type snextc ()
Getting the next character.
int_type sputbackc (char_type __c)
Pushing characters back into the input stream.
int_type sputc (char_type __c)
Entry point for all single-character output functions.
streamsize sputn (const char_type *__s, streamsize __n)
Entry point for all single-character output functions.
int_type sungetc ()
Moving backwards in the input stream.
void swap (stdio_sync_filebuf &__fb)

  Protected Member Functions
void __safe_gbump (streamsize __n)
void __safe_pbump (streamsize __n)
char_type * eback () const
Access to the get area.
char_type * egptr () const
char_type * epptr () const
void gbump (int __n)
Moving the read position.
char_type * gptr () const
virtual void imbue (const locale &__loc)
Changes translations.
virtual int_type overflow (int_type __c=traits_type::eof())
virtual int_type overflow (int_type __c=traits_type::eof())
Consumes data from the buffer; writes to the controlled sequence.
virtual int_type pbackfail (int_type __c=traits_type::eof())
virtual int_type pbackfail (int_type __c=traits_type::eof())
Tries to back up the input sequence.
char_type * pbase () const
Access to the put area.
void pbump (int __n)
Moving the write position.
char_type * pptr () const
virtual pos_type seekoff (off_type, ios_base::seekdir, ios_base::openmode=ios_base::in|ios_base::out)
Alters the stream positions.
virtual std::streampos seekoff (std::streamoff __off, std::ios_base::seekdir __dir, std::ios_base::openmode=std::ios_base::in|std::ios_base::out)
virtual std::streampos seekpos (std::streampos __pos, std::ios_base::openmode __mode=std::ios_base::in|std::ios_base::out)
Alters the stream positions.
virtual basic_streambuf< char_type, std::char_traits< _CharT > > * setbuf (char_type *, streamsize)
Manipulates the buffer.
void setg (char_type *__gbeg, char_type *__gnext, char_type *__gend)
Setting the three read area pointers.
void setp (char_type *__pbeg, char_type *__pend)
Setting the three write area pointers.
virtual streamsize showmanyc ()
Investigating the data available.
void swap (basic_streambuf &__sb)
virtual int sync ()
Synchronizes the buffer arrays with the controlled sequences.
int_type syncgetc ()
stdio_sync_filebuf< char >::int_type syncgetc ()
stdio_sync_filebuf< wchar_t >::int_type syncgetc ()
int_type syncputc (int_type __c)
stdio_sync_filebuf< char >::int_type syncputc (int_type __c)
stdio_sync_filebuf< wchar_t >::int_type syncputc (int_type __c)
int_type syncungetc (int_type __c)
stdio_sync_filebuf< char >::int_type syncungetc (int_type __c)
stdio_sync_filebuf< wchar_t >::int_type syncungetc (int_type __c)
virtual int_type uflow ()
Fetches more data from the controlled sequence.
virtual int_type underflow ()
Fetches more data from the controlled sequence.
std::streamsize xsgetn (char *__s, std::streamsize __n)
virtual std::streamsize xsgetn (char_type *__s, std::streamsize __n)
virtual streamsize xsgetn (char_type *__s, streamsize __n)
Multiple character extraction.
std::streamsize xsgetn (wchar_t *__s, std::streamsize __n)
std::streamsize xsputn (const char *__s, std::streamsize __n)
virtual std::streamsize xsputn (const char_type *__s, std::streamsize __n)
virtual streamsize xsputn (const char_type *__s, streamsize __n)
Multiple character insertion.
std::streamsize xsputn (const wchar_t *__s, std::streamsize __n)

  Protected Attributes
locale _M_buf_locale
Current locale setting.
char_type * _M_in_beg
Start of get area.
char_type * _M_in_cur
Current read area.
char_type * _M_in_end
End of get area.
char_type * _M_out_beg
Start of put area.
char_type * _M_out_cur
Current put area.
char_type * _M_out_end
End of put area.

Detailed Description

  template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
class __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >" Provides a layer of compatibility for C. This GNU extension provides extensions for working with standard C FILE*'s. It must be instantiated by the user with the type of character used in the file stream, e.g., stdio_filebuf<char>.

Definition at line 57 of file stdio_sync_filebuf.h.

Member Function Documentation

  char_type* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::eback () const [inline], [protected], [inherited]

Access to the get area. These functions are only available to other protected functions, including derived classes.

•   eback() returns the beginning pointer for the input sequence

•   gptr() returns the next pointer for the input sequence

•   egptr() returns the end pointer for the input sequence

Definition at line 489 of file streambuf.

  template<typename _CharT , typename _Traits = std::char_traits<_CharT>> std::__c_file* __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >::file () [inline]

Returns
    The underlying FILE*.

This function can be used to access the underlying C file pointer. Note that there is no way for the library to track what you do with the file, so be careful.

Definition at line 118 of file stdio_sync_filebuf.h.

  void std::basic_streambuf< _CharT, std::char_traits< _CharT > >::gbump (int __n) [inline], [protected], [inherited]

Moving the read position.

Parameters
    __n The delta by which to move.

This just advances the read position without returning any data.

Definition at line 505 of file streambuf.

  locale std::basic_streambuf< _CharT, std::char_traits< _CharT > >::getloc () const [inline], [inherited]

Locale access.

Returns
    The current locale in effect.

If pubimbue(loc) has been called, then the most recent loc is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 233 of file streambuf.

  virtual void std::basic_streambuf< _CharT, std::char_traits< _CharT > >::imbue (const locale & __loc) [inline], [protected], [virtual], [inherited]

Changes translations.

Parameters
    __loc A new locale.

Translations done during I/O which depend on the current locale are changed by this call. The standard adds, Between invocations of this function a class derived from streambuf can safely cache results of calls to locale functions and to members of facets so obtained.

Note
    Base class version does nothing.

Reimplemented in std::basic_filebuf< _CharT, std::char_traits< _CharT > >.

Definition at line 583 of file streambuf.

  streamsize std::basic_streambuf< _CharT, std::char_traits< _CharT > >::in_avail () [inline], [inherited]

Looking ahead into the stream.

Returns
    The number of characters available.

If a read position is available, returns the number of characters available for reading before the buffer must be refilled. Otherwise returns the derived showmanyc().

Definition at line 291 of file streambuf.

  virtual int_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::overflow (int_type __c = traits_type::eof()) [inline], [protected], [virtual], [inherited]

Consumes data from the buffer; writes to the controlled sequence.

Parameters
    __c An additional character to consume.

Returns
    eof() to indicate failure, something else (usually __c, or not_eof())

Informally, this function is called when the output buffer is full (or does not exist, as buffering need not actually be done). If a buffer exists, it is consumed, with some effect on the controlled sequence. (Typically, the buffer is written out to the sequence verbatim.) In either case, the character c is also written out, if __c is not eof().

For a formal definition of this function, see a good text such as Langer & Kreft, or [27.5.2.4.5]/3-7.

A functioning output streambuf can be created by overriding only this function (no buffer area will be used).

Note
    Base class version does nothing, returns eof().

Reimplemented in std::basic_filebuf< _CharT, std::char_traits< _CharT > >.

Definition at line 775 of file streambuf.

  virtual int_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::pbackfail (int_type __c = traits_type::eof()) [inline], [protected], [virtual], [inherited]

Tries to back up the input sequence.

Parameters
    __c The character to be inserted back into the sequence.

Returns
    eof() on failure, some other value on success

Postcondition
    The constraints of gptr(), eback(), and pptr() are the same as for underflow().

Note
    Base class version does nothing, returns eof().

Reimplemented in std::basic_filebuf< _CharT, std::char_traits< _CharT > >.

Definition at line 731 of file streambuf.

  char_type* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::pbase () const [inline], [protected], [inherited]

Access to the put area. These functions are only available to other protected functions, including derived classes.

•   pbase() returns the beginning pointer for the output sequence

•   pptr() returns the next pointer for the output sequence

•   epptr() returns the end pointer for the output sequence

Definition at line 536 of file streambuf.

  void std::basic_streambuf< _CharT, std::char_traits< _CharT > >::pbump (int __n) [inline], [protected], [inherited]

Moving the write position.

Parameters
    __n The delta by which to move.

This just advances the write position without returning any data.

Definition at line 552 of file streambuf.

  locale std::basic_streambuf< _CharT, std::char_traits< _CharT > >::pubimbue (const locale & __loc) [inline], [inherited]

Entry point for imbue().

Parameters
    __loc The new locale.

Returns
    The previous locale.

Calls the derived imbue(__loc).

Definition at line 216 of file streambuf.

  pos_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode = ios_base::in | ios_base::out) [inline], [inherited]

Alters the stream position.

Parameters
    __off Offset.
    __way Value for ios_base::seekdir.
    __mode Value for ios_base::openmode.

Calls virtual seekoff function.

Definition at line 258 of file streambuf.

  pos_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::pubseekpos (pos_type __sp, ios_base::openmode __mode = ios_base::in | ios_base::out) [inline], [inherited]

Alters the stream position.

Parameters
    __sp Position
    __mode Value for ios_base::openmode.

Calls virtual seekpos function.

Definition at line 270 of file streambuf.

  basic_streambuf* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::pubsetbuf (char_type * __s, streamsize __n) [inline], [inherited]

Entry points for derived buffer functions. The public versions of pubfoo dispatch to the protected derived foo member functions, passing the arguments (if any) and returning the result unchanged.

Definition at line 246 of file streambuf.

  int std::basic_streambuf< _CharT, std::char_traits< _CharT > >::pubsync () [inline], [inherited]

Calls virtual sync function.

Definition at line 278 of file streambuf.

  int_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::sbumpc () [inline], [inherited]

Getting the next character.

Returns
    The next character, or eof.

If the input read position is available, returns that character and increments the read pointer, otherwise calls and returns uflow().

Definition at line 323 of file streambuf.

  virtual pos_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::seekoff (off_type, ios_base::seekdir, ios_base::openmode = ios_base::in | ios_base::out) [inline], [protected], [virtual], [inherited]

Alters the stream positions. Each derived class provides its own appropriate behavior.

Note
    Base class version does nothing, returns a pos_type that represents an invalid stream position.

Reimplemented in std::basic_filebuf< _CharT, std::char_traits< _CharT > >.

Definition at line 609 of file streambuf.

  template<typename _CharT , typename _Traits = std::char_traits<_CharT>> virtual std::streampos __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >::seekpos (std::streampos, std::ios_base::openmode = std::ios_base::in | std::ios_base::out) [inline], [protected], [virtual]

Alters the stream positions. Each derived class provides its own appropriate behavior.

Note
    Base class version does nothing, returns a pos_type that represents an invalid stream position.

Reimplemented from std::basic_streambuf< _CharT, std::char_traits< _CharT > >.

Definition at line 216 of file stdio_sync_filebuf.h.

References std::ios_base::beg.

  virtual basic_streambuf<char_type,std::char_traits< _CharT > >* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::setbuf (char_type *, streamsize) [inline], [protected], [virtual], [inherited]

Manipulates the buffer. Each derived class provides its own appropriate behavior. See the next-to-last paragraph of https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering for more on this function.

Note
    Base class version does nothing, returns this.

Reimplemented in std::basic_filebuf< _CharT, std::char_traits< _CharT > >.

Definition at line 598 of file streambuf.

  void std::basic_streambuf< _CharT, std::char_traits< _CharT > >::setg (char_type * __gbeg, char_type * __gnext, char_type * __gend) [inline], [protected], [inherited]

Setting the three read area pointers.

Parameters
    __gbeg A pointer.
    __gnext A pointer.
    __gend A pointer.

Postcondition
    __gbeg == eback(), __gnext == gptr(), and __gend == egptr()

Definition at line 516 of file streambuf.

  void std::basic_streambuf< _CharT, std::char_traits< _CharT > >::setp (char_type * __pbeg, char_type * __pend) [inline], [protected], [inherited]

Setting the three write area pointers.

Parameters
    __pbeg A pointer.
    __pend A pointer.

Postcondition
    __pbeg == pbase(), __pbeg == pptr(), and __pend == epptr()

Definition at line 562 of file streambuf.

  int_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::sgetc () [inline], [inherited]

Getting the next character.

Returns
    The next character, or eof.

If the input read position is available, returns that character, otherwise calls and returns underflow(). Does not move the read position after fetching the character.

Definition at line 345 of file streambuf.

  streamsize std::basic_streambuf< _CharT, std::char_traits< _CharT > >::sgetn (char_type * __s, streamsize __n) [inline], [inherited]

Entry point for xsgetn.

Parameters
    __s A buffer area.
    __n A count.

Returns xsgetn(__s,__n). The effect is to fill __s[0] through __s[__n-1] with characters from the input sequence, if possible.

Definition at line 364 of file streambuf.

  virtual streamsize std::basic_streambuf< _CharT, std::char_traits< _CharT > >::showmanyc [inline], [protected], [virtual], [inherited]

Investigating the data available.

Returns
    An estimate of the number of characters available in the input sequence, or -1.

If it returns a positive value, then successive calls to underflow() will not return traits::eof() until at least that number of characters have been supplied. If showmanyc() returns -1, then calls to underflow() or uflow() will fail. [27.5.2.4.3]/1

Note
    Base class version does nothing, returns zero.

    The standard adds that the intention is not only that the calls [to underflow or uflow] will not return eof() but that they will return immediately.

    The standard adds that the morphemes of showmanyc are es-how-many-see, not show-manic.

Reimplemented in std::basic_filebuf< _CharT, std::char_traits< _CharT > >.

Definition at line 656 of file streambuf.

  int_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::snextc () [inline], [inherited]

Getting the next character.

Returns
    The next character, or eof.

Calls sbumpc(), and if that function returns traits::eof(), so does this function. Otherwise, sgetc().

Definition at line 305 of file streambuf.

  int_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::sputbackc (char_type __c) [inline], [inherited]

Pushing characters back into the input stream.

Parameters
    __c The character to push back.

Returns
    The previous character, if possible.

Similar to sungetc(), but __c is pushed onto the stream instead of the previous character. If successful, the next character fetched from the input stream will be __c.

Definition at line 379 of file streambuf.

  int_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::sputc (char_type __c) [inline], [inherited]

Entry point for all single-character output functions.

Parameters
    __c A character to output.

Returns
    __c, if possible.

One of two public output functions.

If a write position is available for the output sequence (i.e., the buffer is not full), stores __c in that position, increments the position, and returns traits::to_int_type(__c). If a write position is not available, returns overflow(__c).

Definition at line 431 of file streambuf.

  streamsize std::basic_streambuf< _CharT, std::char_traits< _CharT > >::sputn (const char_type * __s, streamsize __n) [inline], [inherited]

Entry point for all single-character output functions.

Parameters
    __s A buffer read area.
    __n A count.

One of two public output functions.

Returns xsputn(__s,__n). The effect is to write __s[0] through __s[__n-1] to the output sequence, if possible.

Definition at line 457 of file streambuf.

  int_type std::basic_streambuf< _CharT, std::char_traits< _CharT > >::sungetc () [inline], [inherited]

Moving backwards in the input stream.

Returns
    The previous character, if possible.

If a putback position is available, this function decrements the input pointer and returns that character. Otherwise, calls and returns pbackfail(). The effect is to unget the last character gotten.

Definition at line 404 of file streambuf.

  template<typename _CharT , typename _Traits = std::char_traits<_CharT>> virtual int __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >::sync () [inline], [protected], [virtual]

Synchronizes the buffer arrays with the controlled sequences.

Returns
    -1 on failure.

Each derived class provides its own appropriate behavior, including the definition of failure.

Note
    Base class version does nothing, returns zero.

Reimplemented from std::basic_streambuf< _CharT, std::char_traits< _CharT > >.

Definition at line 190 of file stdio_sync_filebuf.h.

  template<typename _CharT , typename _Traits = std::char_traits<_CharT>> virtual int_type __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >::uflow () [inline], [protected], [virtual]

Fetches more data from the controlled sequence.

Returns
    The first character from the pending sequence.

Informally, this function does the same thing as underflow(), and in fact is required to call that function. It also returns the new character, like underflow() does. However, this function also moves the read position forward by one.

Reimplemented from std::basic_streambuf< _CharT, std::char_traits< _CharT > >.

Definition at line 138 of file stdio_sync_filebuf.h.

  template<typename _CharT , typename _Traits = std::char_traits<_CharT>> virtual int_type __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >::underflow () [inline], [protected], [virtual]

Fetches more data from the controlled sequence.

Returns
    The first character from the pending sequence.

Informally, this function is called when the input buffer is exhausted (or does not exist, as buffering need not actually be done). If a buffer exists, it is refilled. In either case, the next available character is returned, or traits::eof() to indicate a null pending sequence.

For a formal definition of the pending sequence, see a good text such as Langer & Kreft, or [27.5.2.4.3]/7-14.

A functioning input streambuf can be created by overriding only this function (no buffer area will be used). For an example, see https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html

Note
    Base class version does nothing, returns eof().

Reimplemented from std::basic_streambuf< _CharT, std::char_traits< _CharT > >.

Definition at line 131 of file stdio_sync_filebuf.h.

  streamsize std::basic_streambuf< _CharT, std::char_traits< _CharT > >::xsgetn (char_type * __s, streamsize __n) [protected], [virtual], [inherited]

Multiple character extraction.

Parameters
    __s A buffer area.
    __n Maximum number of characters to assign.

Returns
    The number of characters assigned.

Fills __s[0] through __s[__n-1] with characters from the input sequence, as if by sbumpc(). Stops when either __n characters have been copied, or when traits::eof() would be copied.

It is expected that derived classes provide a more efficient implementation by overriding this definition.

Reimplemented in std::basic_filebuf< _CharT, std::char_traits< _CharT > >.

Definition at line 672 of file streambuf.tcc.

  streamsize std::basic_streambuf< _CharT, std::char_traits< _CharT > >::xsputn (const char_type * __s, streamsize __n) [protected], [virtual], [inherited]

Multiple character insertion.

Parameters
    __s A buffer area.
    __n Maximum number of characters to write.

Returns
    The number of characters written.

Writes __s[0] through __s[__n-1] to the output sequence, as if by sputc(). Stops when either n characters have been copied, or when sputc() would return traits::eof().

It is expected that derived classes provide a more efficient implementation by overriding this definition.

Reimplemented in std::basic_filebuf< _CharT, std::char_traits< _CharT > >.

Definition at line 749 of file streambuf.tcc.

Member Data Documentation

  locale std::basic_streambuf< _CharT, std::char_traits< _CharT > >::_M_buf_locale [protected], [inherited]

Current locale setting.

Definition at line 199 of file streambuf.

  char_type* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::_M_in_beg [protected], [inherited]

Start of get area.

Definition at line 191 of file streambuf.

  char_type* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::_M_in_cur [protected], [inherited]

Current read area.

Definition at line 192 of file streambuf.

  char_type* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::_M_in_end [protected], [inherited]

End of get area.

Definition at line 193 of file streambuf.

  char_type* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::_M_out_beg [protected], [inherited]

Start of put area.

Definition at line 194 of file streambuf.

  char_type* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::_M_out_cur [protected], [inherited]

Current put area.

Definition at line 195 of file streambuf.

  char_type* std::basic_streambuf< _CharT, std::char_traits< _CharT > >::_M_out_end [protected], [inherited]

End of put area.

Definition at line 196 of file streambuf.

Author

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