newlib-cygwin/newlib/libc/stdio/fileno.c

63 lines
1.6 KiB
C

/*
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
/*
FUNCTION
<<fileno>>---return file descriptor associated with stream
INDEX
fileno
ANSI_SYNOPSIS
#include <stdio.h>
int fileno(FILE *<[fp]>);
TRAD_SYNOPSIS
#include <stdio.h>
int fileno(<[fp]>)
FILE *<[fp]>;
DESCRIPTION
You can use <<fileno>> to return the file descriptor identified by <[fp]>.
RETURNS
<<fileno>> returns a non-negative integer when successful.
If <[fp]> is not an open stream, <<fileno>> returns -1.
PORTABILITY
<<fileno>> is not part of ANSI C.
POSIX requires <<fileno>>.
Supporting OS subroutines required: none.
*/
#include <_ansi.h>
#include <stdio.h>
#include "local.h"
int
_DEFUN(fileno, (f),
FILE * f)
{
int result;
CHECK_INIT (_REENT, f);
_flockfile (f);
result = __sfileno (f);
_funlockfile (f);
return result;
}