STDIO_EXT(3)                                        Linux Programmer's Manual                                       STDIO_EXT(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 3.25 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/.



                                                           2001-12-16                                               STDIO_EXT(3)