Linux manual pages Section 3  

Name

__fbufsize, __flbf, __fpending, __fpurge, __freadable, __freading, __fsetlocking, __fwritable, __fwriting, _flushlbf — interfaces to stdio FILE structure

Synopsis

#include <stdio.h>
#include <stdio_ext.h>
size_t __fbufsize( FILE *stream);
 
size_t __fpending( FILE *stream);
 
int __flbf( FILE *stream);
 
int __freadable( FILE *stream);
 
int __fwritable( FILE *stream);
 
int __freading( FILE *stream);
 
int __fwriting( FILE *stream);
 
int __fsetlocking( FILE *stream,
  int type);
 
void _flushlbf( void);  
 
void __fpurge( FILE *stream);
 

DESCRIPTION

Solaris introduced routines to allow portable access to the internals of the FILE structure, and glibc also implemented these.

The __fbufsize() function returns the size of the buffer currently used by the given stream.

The __fpending() function returns the number of bytes in the output buffer. For wide-oriented streams the unit is wide characters. This function is undefined on buffers in reading mode, or opened read-only.

The __flbf() function returns a nonzero value if the stream is line-buffered, and zero otherwise.

The __freadable() function returns a nonzero value if the stream allows reading, and zero otherwise.

The __fwritable() function returns a nonzero value if the stream allows writing, and zero otherwise.

The __freading() function returns a nonzero value if the stream is read-only, or if the last operation on the stream was a read operation, and zero otherwise.

The __fwriting() function returns a nonzero value if the stream is write-only (or append-only), or if the last operation on the stream was a write operation, and zero otherwise.

The __fsetlocking() function can be used to select the desired type of locking on the stream. It returns the current type. The type argument can take the following three values:

FSETLOCKING_INTERNAL

Perform implicit locking around every operation on the given stream (except for the *_unlocked ones). This is the default.

FSETLOCKING_BYCALLER

The caller will take care of the locking (possibly using flockfile(3) in case there is more than one thread), and the stdio routines will not do locking until the state is reset to FSETLOCKING_INTERNAL.

FSETLOCKING_QUERY

Don't change the type of locking. (Only return it.)

The _flushlbf() function flushes all line-buffered streams. (Presumably so that output to a terminal is forced out, say before reading keyboard input.)

The __fpurge() function discards the contents of the stream's buffer.

SEE ALSO

flockfile(3), fpurge(3)

COLOPHON

This page is part of release 3.33 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://man7.org/linux/man-pages/.


  Copyright (C) 2001 Andries Brouwer <aebcwi.nl>.

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.