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 1.9 2007/05/31 19:19:32 jmc Exp $ 33.\" 34.Dd $Mdocdate: May 31 2007 $ 35.Dt STRERROR 3 36.Os 37.Sh NAME 38.Nm strerror 39.Nd get error message string 40.Sh SYNOPSIS 41.Fd #include <string.h> 42.Ft char * 43.Fn strerror "int errnum" 44.Ft int 45.Fn strerror_r "int errnum" "char *strerrbuf" "size_t buflen" 46.Sh DESCRIPTION 47The 48.Fn strerror 49and 50.Fn strerror_r 51functions map the error number 52.Fa errnum 53to a language-dependent error message string. 54.Pp 55.Fn strerror 56returns a string containing a maximum of 57.Dv NL_TEXTMAX 58characters, including the trailing NUL. 59This string is not to be modified by the calling program, 60but may be overwritten by subsequent calls to 61.Fn strerror . 62.Pp 63.Fn strerror_r 64is a thread safe version of 65.Fn strerror 66that places the error message in the specified buffer 67.Fa strerrbuf . 68.Sh RETURN VALUES 69.Fn strerror 70returns a pointer to the error message string. 71If an error occurs, the error code is stored in 72.Va errno . 73.Pp 74.Fn strerror_r 75returns zero upon successful completion. 76If an error occurs, the error code is stored in 77.Va errno 78and the error code is returned. 79.Sh ERRORS 80.Fn strerror 81and 82.Fn strerror_r 83may fail if: 84.Bl -tag -width Er 85.It Bq Er EINVAL 86.Fa errnum 87is not a valid error number. 88The returned error string will consist of an error message that includes 89.Fa errnum . 90.El 91.Pp 92.Fn strerror_r 93may fail if: 94.Bl -tag -width Er 95.It Bq Er ERANGE 96The error message is larger than 97.Fa buflen 98characters. 99The message will be truncated to fit. 100.El 101.Sh SEE ALSO 102.Xr intro 2 , 103.Xr perror 3 , 104.Xr setlocale 3 105.Sh STANDARDS 106The 107.Fn strerror 108function conforms to 109.St -ansiC . 110The 111.Fn strerror_r 112function conforms to 113.St -p1003.1 . 114