1.\" $OpenBSD: ferror.3,v 1.11 2021/10/31 16:56:47 schwarze Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Chris Torek and the American National Standards Committee X3, 8.\" on Information Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.Dd $Mdocdate: October 31 2021 $ 35.Dt FERROR 3 36.Os 37.Sh NAME 38.Nm clearerr , 39.Nm feof , 40.Nm ferror , 41.Nm fileno 42.Nd check and reset stream status 43.Sh SYNOPSIS 44.In stdio.h 45.Ft void 46.Fn clearerr "FILE *stream" 47.Ft int 48.Fn feof "FILE *stream" 49.Ft int 50.Fn ferror "FILE *stream" 51.Ft int 52.Fn fileno "FILE *stream" 53.Sh DESCRIPTION 54The function 55.Fn clearerr 56clears the end-of-file and error indicators for the stream pointed to by 57.Fa stream . 58.Pp 59The function 60.Fn feof 61tests the end-of-file indicator for the stream pointed to by 62.Fa stream , 63returning non-zero if it is set. 64.Pp 65The function 66.Fn ferror 67tests the error indicator for the stream pointed to by 68.Fa stream , 69returning non-zero if it is set. 70The error indicator can only be reset by the 71.Fn clearerr 72function. 73.Pp 74The function 75.Fn fileno 76returns the file descriptor associated with the given 77.Fa stream 78or \-1 if it is not associated with any file descriptor, 79for example if it was created with 80.Xr fmemopen 3 , 81.Xr open_memstream 3 , 82or 83.Xr funopen 3 . 84.Sh ERRORS 85These functions should not fail and do not set the external 86variable 87.Va errno . 88.Sh SEE ALSO 89.Xr open 2 , 90.Xr stdio 3 91.Sh STANDARDS 92The functions 93.Fn clearerr , 94.Fn feof , 95and 96.Fn ferror 97conform to 98.St -ansiC . 99The function 100.Fn fileno 101conforms to 102.St -p1003.1-90 . 103.Sh HISTORY 104The functions 105.Fn clearerr , 106.Fn feof , 107.Fn ferror , 108and 109.Fn fileno 110first appeared in 111.At v7 . 112