1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek and the American National Standards Committee X3, 6.\" on Information Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)ferror.3 8.2 (Berkeley) 4/19/94 37.\" $FreeBSD$ 38.\" 39.Dd January 10, 2003 40.Dt FERROR 3 41.Os 42.Sh NAME 43.Nm clearerr , 44.Nm clearerr_unlocked , 45.Nm feof , 46.Nm feof_unlocked , 47.Nm ferror , 48.Nm ferror_unlocked , 49.Nm fileno , 50.Nm fileno_unlocked 51.Nd check and reset stream status 52.Sh LIBRARY 53.Lb libc 54.Sh SYNOPSIS 55.In stdio.h 56.Ft void 57.Fn clearerr "FILE *stream" 58.Ft void 59.Fn clearerr_unlocked "FILE *stream" 60.Ft int 61.Fn feof "FILE *stream" 62.Ft int 63.Fn feof_unlocked "FILE *stream" 64.Ft int 65.Fn ferror "FILE *stream" 66.Ft int 67.Fn ferror_unlocked "FILE *stream" 68.Ft int 69.Fn fileno "FILE *stream" 70.Ft int 71.Fn fileno_unlocked "FILE *stream" 72.Sh DESCRIPTION 73The function 74.Fn clearerr 75clears the end-of-file and error indicators for the stream pointed 76to by 77.Fa stream . 78.Pp 79The function 80.Fn feof 81tests the end-of-file indicator for the stream pointed to by 82.Fa stream , 83returning non-zero if it is set. 84The end-of-file indicator can only be cleared by the function 85.Fn clearerr . 86.Pp 87The function 88.Fn ferror 89tests the error indicator for the stream pointed to by 90.Fa stream , 91returning non-zero if it is set. 92The error indicator can only be reset by the 93.Fn clearerr 94function. 95.Pp 96The function 97.Fn fileno 98examines the argument 99.Fa stream 100and returns its integer descriptor. 101.Pp 102The 103.Fn clearerr_unlocked , 104.Fn feof_unlocked , 105.Fn ferror_unlocked , 106and 107.Fn fileno_unlocked 108functions are equivalent to 109.Fn clearerr , 110.Fn feof , 111.Fn ferror , 112and 113.Fn fileno 114respectively, except that the caller is responsible for locking the stream 115with 116.Xr flockfile 3 117before calling them. 118These functions may be used to avoid the overhead of locking the stream 119and to prevent races when multiple threads are operating on the same stream. 120.Sh ERRORS 121These functions should not fail and do not set the external 122variable 123.Va errno . 124.Sh SEE ALSO 125.Xr open 2 , 126.Xr fdopen 3 , 127.Xr flockfile 3 , 128.Xr stdio 3 129.Sh STANDARDS 130The functions 131.Fn clearerr , 132.Fn feof , 133and 134.Fn ferror 135conform to 136.St -isoC . 137