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.
ATTRIBUTES¶
Multithreading (see pthreads(7))¶
The
__fbufsize(),
__fpending(),
__fpurge() and
__fsetlocking() functions do not lock the stream, so they are not
thread-safe.
The
__flbf(),
__freadable(),
__freading(),
__fwritable(),
__fwriting() and
_flushlbf() functions are
thread-safe.
SEE ALSO¶
flockfile(3),
fpurge(3)
COLOPHON¶
This page is part of release 3.74 of the Linux
man-pages project. A
description of the project, information about reporting bugs, and the latest
version of this page, can be found at
http://www.kernel.org/doc/man-pages/.
