stdio_ext(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | ATTRIBUTES | SEE ALSO | COLOPHON

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

NAME         top

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

SYNOPSIS         top

       #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         top

       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         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────────────────┬───────────────┬─────────────────────┐
       │Interface                 Attribute     Value               │
       ├──────────────────────────┼───────────────┼─────────────────────┤
       │__fbufsize(),             │ Thread safety │ MT-Safe race:stream │
       │__fpending(), __fpurge(), │               │                     │
       │__fsetlocking()           │               │                     │
       ├──────────────────────────┼───────────────┼─────────────────────┤
       │__flbf(), __freadable(),  │ Thread safety │ MT-Safe             │
       │__freading(),             │               │                     │
       │__fwritable(),            │               │                     │
       │__fwriting(), _flushlbf() │               │                     │
       └──────────────────────────┴───────────────┴─────────────────────┘

SEE ALSO         top

       flockfile(3), fpurge(3)

COLOPHON         top

       This page is part of release 5.11 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
       https://www.kernel.org/doc/man-pages/.

                               2021-03-22                   STDIO_EXT(3)

Pages that refer to this page: fpurge(3)