1.\" $NetBSD: readlink.2,v 1.26 2010/05/31 12:16:20 njoly Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)readlink.2 8.1 (Berkeley) 6/4/93 31.\" 32.Dd May 11, 2004 33.Dt READLINK 2 34.Os 35.Sh NAME 36.Nm readlink 37.Nd read value of a symbolic link 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In unistd.h 42.Ft ssize_t 43.Fn readlink "const char * restrict path" "char * restrict buf" "size_t bufsiz" 44.Sh DESCRIPTION 45.Fn readlink 46places the contents of the symbolic link 47.Fa path 48in the buffer 49.Fa buf , 50which has size 51.Fa bufsiz . 52.Fn readlink 53does not append a 54.Dv NUL 55character to 56.Fa buf . 57.Sh RETURN VALUES 58The call returns the count of characters placed in the buffer 59if it succeeds, or a \-1 if an error occurs, placing the error 60code in the global variable 61.Va errno . 62.Sh EXAMPLES 63A typical use is illustrated in the following piece of code 64which reads the contents of a symbolic link named 65.Pa /symbolic/link 66and stores them as null-terminated string: 67.Bd -literal -offset indent 68#include \*[Lt]limits.h\*[Gt] 69#include \*[Lt]unistd.h\*[Gt] 70 71char buf[PATH_MAX]; 72ssize_t len; 73 74if ((len = readlink("/symbolic/link", buf, sizeof(buf)-1)) == -1) 75 error handling; 76buf[len] = '\e0'; 77.Ed 78.Sh ERRORS 79.Fn readlink 80will fail if: 81.Bl -tag -width Er 82.It Bq Er ENOTDIR 83A component of the path prefix is not a directory. 84.It Bq Er ENAMETOOLONG 85A component of a pathname exceeded 86.Brq Dv NAME_MAX 87characters, or an entire path name exceeded 88.Brq Dv PATH_MAX 89characters. 90.It Bq Er ENOENT 91The named file does not exist. 92.It Bq Er EACCES 93Search permission is denied for a component of the path prefix. 94.It Bq Er ELOOP 95Too many symbolic links were encountered in translating the pathname. 96.It Bq Er EINVAL 97The named file is not a symbolic link. 98.It Bq Er EIO 99An I/O error occurred while reading from the file system. 100.It Bq Er EFAULT 101.Fa buf 102extends outside the process's allocated address space. 103.El 104.Sh SEE ALSO 105.Xr lstat 2 , 106.Xr stat 2 , 107.Xr symlink 2 , 108.Xr symlink 7 109.Sh STANDARDS 110The 111.Fn readlink 112function conforms to 113.St -p1003.1-2001 . 114.Sh HISTORY 115The 116.Fn readlink 117function appeared in 118.Bx 4.2 . 119The type returned was changed from 120.Ft int 121to 122.Ft ssize_t 123in 124.Nx 2.1 . 125