STDIOEXT(3) Linux Programmer's Manual STDIOEXT(3)

NAME
       fbufsize,  flbf,  fpending,  fpurge,  freadable,  freading,
       fsetlocking, fwritable, fwriting, flushlbf - interfaces to stdio
       FILE structure

SYNOPSIS
       #include 
       #include 

       sizet fbufsize(FILE *stream);
       sizet 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:

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

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

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

       The flushlbf() function flushes all line-buffered  streams.   (Presum‐
       ably  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
       For  an  explanation  of  the  terms  used   in   this   section,   see
       attributes(7).

       ┌─────────────────────────────┬───────────────┬─────────────────────┐
       │Interface                    │ Attribute     │ Value               │
       ├─────────────────────────────┼───────────────┼─────────────────────┤
       │fbufsize(), fpending(),  │ Thread safety │ MT-Safe race:stream │
       │fpurge(), fsetlocking()  │               │                     │
       ├─────────────────────────────┼───────────────┼─────────────────────┤
       │flbf(), freadable(),     │ Thread safety │ MT-Safe             │
       │freading(), fwritable(), │               │                     │
       │fwriting(), flushlbf()    │               │                     │
       └─────────────────────────────┴───────────────┴─────────────────────┘
SEE ALSO
       flockfile(3), fpurge(3)

COLOPHON
       This  page  is  part of release 3.53 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                      STDIOEXT(3)