| __gnu_cxx::stdio_filebuf< _CharT, _Traits >(3cxx) | __gnu_cxx::stdio_filebuf< _CharT, _Traits >(3cxx) |
__gnu_cxx::stdio_filebuf< _CharT, _Traits > - Provides a layer of compatibility for C/POSIX.
#include <stdio_filebuf.h>
Inherits std::basic_filebuf< _CharT, _Traits >.
typedef codecvt< char_type, char, __state_type >
__codecvt_type
typedef __basic_file< char > __file_type
typedef basic_filebuf< char_type, traits_type >
__filebuf_type
typedef traits_type::state_type __state_type
typedef basic_streambuf< char_type, traits_type >
__streambuf_type
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 std::size_t size_t
typedef _Traits traits_type
stdio_filebuf ()
stdio_filebuf (int __fd, std::ios_base::openmode __mode, size_t
__size=static_cast< size_t >(BUFSIZ))
stdio_filebuf (std::__c_file *__f, std::ios_base::openmode
__mode, size_t __size=static_cast< size_t >(BUFSIZ))
stdio_filebuf (stdio_filebuf &&)=default
virtual ~stdio_filebuf ()
__filebuf_type * close ()
Closes the currently associated file. int fd ()
std::__c_file * file ()
locale getloc () const
Locale access. streamsize in_avail ()
Looking ahead into the stream. bool is_open () const throw ()
Returns true if the external file is open. template<typename _Path >
_If_fs_path< _Path, __filebuf_type * > open (const _Path
&__s, ios_base::openmode __mode)
Opens an external file. __filebuf_type * open (const char *__s,
ios_base::openmode __mode)
Opens an external file. __filebuf_type * open (const
std::string &__s, ios_base::openmode __mode)
Opens an external file. stdio_filebuf & operator=
(stdio_filebuf &&)=default
locale pubimbue (const locale &__loc)
Entry point for imbue(). 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 (basic_filebuf
&)
void swap (stdio_filebuf &__fb)
basic_streambuf * pubsetbuf (char_type *__s, streamsize __n)
Entry points for derived buffer functions. 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. int pubsync ()
Calls virtual sync function.
void __safe_gbump (streamsize __n)
void __safe_pbump (streamsize __n)
void _M_allocate_internal_buffer ()
bool _M_convert_to_external (char_type *, streamsize)
void _M_create_pback ()
void _M_destroy_internal_buffer () throw ()
void _M_destroy_pback () throw ()
int _M_get_ext_pos (__state_type &__state)
pos_type _M_seek (off_type __off, ios_base::seekdir __way, __state_type
__state)
void _M_set_buffer (streamsize __off)
bool _M_terminate_output ()
void gbump (int __n)
Moving the read position. virtual void imbue (const locale &__loc)
Changes translations. virtual int_type overflow (int_type
__c=_Traits::eof())
Consumes data from the buffer; writes to the controlled sequence. virtual
int_type pbackfail (int_type __c=_Traits::eof())
Tries to back up the input sequence. void pbump (int __n)
Moving the write position. virtual pos_type seekoff (off_type __off,
ios_base::seekdir __way, ios_base::openmode
__mode=ios_base::in|ios_base::out)
Alters the stream positions. virtual pos_type seekpos (pos_type __pos,
ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions. virtual __streambuf_type * setbuf
(char_type *__s, streamsize __n)
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. virtual int_type
uflow ()
Fetches more data from the controlled sequence. virtual int_type
underflow ()
Fetches more data from the controlled sequence. virtual streamsize
xsgetn (char_type *__s, streamsize __n)
Multiple character extraction. virtual streamsize xsputn (const
char_type *__s, streamsize __n)
Multiple character insertion.
char_type * eback () const
Access to the get area. char_type * gptr () const
Access to the get area. char_type * egptr () const
Access to the get area.
char_type * pbase () const
Access to the put area. char_type * pptr () const
Access to the put area. char_type * epptr () const
Access to the put area.
char_type * _M_buf
Pointer to the beginning of internal buffer. bool _M_buf_allocated
locale _M_buf_locale
Current locale setting. size_t _M_buf_size
const __codecvt_type * _M_codecvt
char * _M_ext_buf
streamsize _M_ext_buf_size
char * _M_ext_end
const char * _M_ext_next
__file_type _M_file
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. __c_lock _M_lock
ios_base::openmode _M_mode
Place to stash in || out || in | out settings for current filebuf. 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. bool _M_reading
__state_type _M_state_beg
__state_type _M_state_cur
__state_type _M_state_last
bool _M_writing
char_type _M_pback
char_type * _M_pback_cur_save
char_type * _M_pback_end_save
bool _M_pback_init
class __gnu_cxx::stdio_filebuf< _CharT, _Traits >"Provides a layer of compatibility for C/POSIX.
This GNU extension provides extensions for working with standard C FILE*'s and POSIX file descriptors. It must be instantiated by the user with the type of character used in the file stream, e.g., stdio_filebuf<char>.
deferred initialization
Parameters
This constructor associates a file stream buffer with an open POSIX file descriptor. The file descriptor will be automatically closed when the stdio_filebuf is closed/destroyed.
Parameters
This constructor associates a file stream buffer with an open C FILE*. The FILE* will not be automatically closed when the stdio_filebuf is closed/destroyed.
Closes the external data stream if the file descriptor constructor was used.
Initializes pback buffers, and moves normal buffers to safety. Assumptions: _M_in_cur has already been moved back
Deactivates pback buffer contents, and restores normal buffer. Assumptions: The pback buffer has only moved forward.
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.
Closes the currently associated file.
Returns
If no file is currently open, this function immediately fails.
If a put buffer area exists, overflow(eof) is called to flush all the characters. The file is then closed.
If any operations fail, this function also fails.
Access to the get area. These functions are only available to other protected functions, including derived classes.
Access to the get area. These functions are only available to other protected functions, including derived classes.
Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::underflow().
Access to the put area. These functions are only available to other protected functions, including derived classes.
Returns
Once associated with an external data stream, this function can be used to access the underlying POSIX file descriptor. Note that there is no way for the library to track what you do with the descriptor, so be careful.
Returns
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.
Moving the read position.
Parameters
This just advances the read position without returning any data.
Locale access.
Returns
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.
Access to the get area. These functions are only available to other protected functions, including derived classes.
Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::underflow().
Changes translations.
Parameters
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
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::cur.
Looking ahead into the stream.
Returns
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().
Returns true if the external file is open.
Opens an external file.
Parameters
Returns
Opens an external file.
Parameters
Returns
If a file is already open, this function immediately fails. Otherwise it tries to open the file named __s using the flags given in __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 | +---------------------------------------------------------+
References std::ios_base::ate, and std::ios_base::end.
Opens an external file.
Parameters
Returns
Consumes data from the buffer; writes to the controlled sequence.
Parameters
Returns
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
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::app, std::ios_base::cur, and std::ios_base::out.
Tries to back up the input sequence.
Parameters
Returns
Postcondition
Note
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::cur, and std::ios_base::in.
Access to the put area. These functions are only available to other protected functions, including derived classes.
Moving the write position.
Parameters
This just advances the write position without returning any data.
Access to the put area. These functions are only available to other protected functions, including derived classes.
Entry point for imbue().
Parameters
Returns
Calls the derived imbue(__loc).
Alters the stream position.
Parameters
Calls virtual seekoff function.
Alters the stream position.
Parameters
Calls virtual seekpos function.
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.
Calls virtual sync function.
Getting the next character.
Returns
If the input read position is available, returns that character and increments the read pointer, otherwise calls and returns uflow().
Alters the stream positions. Each derived class provides its own appropriate behavior.
Note
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::cur.
Alters the stream positions. Each derived class provides its own appropriate behavior.
Note
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::beg.
Manipulates the buffer.
Parameters
Returns
If no file has been opened, and both __s and __n are zero, then the stream becomes unbuffered. Otherwise, __s is used as a buffer; see https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering for more.
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Setting the three read area pointers.
Parameters
Postcondition
Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::wbuffer_convert().
Setting the three write area pointers.
Parameters
Postcondition
Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::wbuffer_convert().
Getting the next character.
Returns
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.
Entry point for xsgetn.
Parameters
Returns xsgetn(__s,__n). The effect is to fill __s[0] through __s[__n-1] with characters from the input sequence, if possible.
Investigating the data available.
Returns
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
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 from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::binary, and std::ios_base::in.
Getting the next character.
Returns
Calls sbumpc(), and if that function returns traits::eof(), so does this function. Otherwise, sgetc().
Pushing characters back into the input stream.
Parameters
Returns
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.
Entry point for all single-character output functions.
Parameters
Returns
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).
Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::overflow().
Entry point for all single-character output functions.
Parameters
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.
Moving backwards in the input stream.
Returns
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.
Synchronizes the buffer arrays with the controlled sequences.
Returns
Each derived class provides its own appropriate behavior, including the definition of failure.
Note
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
Fetches more data from the controlled sequence.
Returns
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 in __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.
Fetches more data from the controlled sequence.
Returns
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
Reimplemented from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::in.
Multiple character extraction.
Parameters
Returns
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 from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::in.
Multiple character insertion.
Parameters
Returns
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 from std::basic_streambuf< _CharT, _Traits >.
References std::ios_base::app, std::min(), and std::ios_base::out.
Pointer to the beginning of internal buffer.
Current locale setting.
Referenced by std::basic_filebuf< _CharT, _Traits >::basic_filebuf().
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.
Buffer for external characters. Used for input when codecvt::always_noconv() == false. When valid, this corresponds to eback().
Size of buffer held by _M_ext_buf.
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().
Start of get area.
Current read area.
End of get area.
Place to stash in || out || in | out settings for current filebuf.
Start of put area.
Current put area.
End of put area.
Necessary bits for putback buffer management.
Note
Necessary bits for putback buffer management.
Note
Necessary bits for putback buffer management.
Note
Necessary bits for putback buffer management.
Note
_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.
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