1.\" Copyright (c) 1980, 1991 Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" 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. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" $OpenBSD: strerror.3,v 1.13 2014/04/07 17:57:56 schwarze Exp $ 33.\" 34.Dd $Mdocdate: April 7 2014 $ 35.Dt STRERROR 3 36.Os 37.Sh NAME 38.Nm strerror , 39.Nm strerror_r 40.Nd get error message string 41.Sh SYNOPSIS 42.In string.h 43.Ft char * 44.Fn strerror "int errnum" 45.Ft int 46.Fn strerror_r "int errnum" "char *strerrbuf" "size_t buflen" 47.Sh DESCRIPTION 48The 49.Fn strerror 50and 51.Fn strerror_r 52functions map the error number 53.Fa errnum 54to a language-dependent error message string. 55.Pp 56.Fn strerror 57returns a string containing a maximum of 58.Dv NL_TEXTMAX 59characters, including the trailing NUL. 60This string is not to be modified by the calling program, 61but may be overwritten by subsequent calls to 62.Fn strerror . 63.Pp 64.Fn strerror_r 65is a thread safe version of 66.Fn strerror 67that places the error message in the specified buffer 68.Fa strerrbuf . 69.Sh RETURN VALUES 70.Fn strerror 71returns a pointer to the error message string. 72If an error occurs, the error code is stored in 73.Va errno . 74.Pp 75.Fn strerror_r 76returns zero upon successful completion. 77If an error occurs, the error code is stored in 78.Va errno 79and the error code is returned. 80.Sh ERRORS 81.Fn strerror 82and 83.Fn strerror_r 84may fail if: 85.Bl -tag -width Er 86.It Bq Er EINVAL 87.Fa errnum 88is not a valid error number. 89The returned error string will consist of an error message that includes 90.Fa errnum . 91.El 92.Pp 93.Fn strerror_r 94may fail if: 95.Bl -tag -width Er 96.It Bq Er ERANGE 97The error message is larger than 98.Fa buflen 99characters. 100The message will be truncated to fit. 101.El 102.Sh SEE ALSO 103.Xr intro 2 , 104.Xr perror 3 , 105.Xr setlocale 3 106.Sh STANDARDS 107The 108.Fn strerror 109function conforms to 110.St -ansiC-99 . 111The 112.Fn strerror_r 113function conforms to 114.St -p1003.1-2008 . 115.Sh HISTORY 116The 117.Fn strerror 118function first appeared in 119.Bx 4.3 Reno . 120The 121.Fn strerror_r 122function first appeared in 123.Ox 3.3 . 124