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 3.54 of the Linux man-pages project.  A description of the project, and
       information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

                                                   2013-06-21                                       STDIO_EXT(3)