125 lines
3.6 KiB
Groff
125 lines
3.6 KiB
Groff
|
.\" $NetBSD: readlink.2,v 1.26 2010/05/31 12:16:20 njoly Exp $
|
||
|
|
.\"
|
||
|
|
.\" Copyright (c) 1983, 1991, 1993
|
||
|
|
.\" The Regents of the University of California. All rights reserved.
|
||
|
|
.\"
|
||
|
|
.\" Redistribution and use in source and binary forms, with or without
|
||
|
|
.\" modification, are permitted provided that the following conditions
|
||
|
|
.\" are met:
|
||
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer.
|
||
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
||
|
|
.\" documentation and/or other materials provided with the distribution.
|
||
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
||
|
|
.\" may be used to endorse or promote products derived from this software
|
||
|
|
.\" without specific prior written permission.
|
||
|
|
.\"
|
||
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
||
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
||
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
.\" SUCH DAMAGE.
|
||
|
|
.\"
|
||
|
|
.\" @(#)readlink.2 8.1 (Berkeley) 6/4/93
|
||
|
|
.\"
|
||
|
|
.Dd May 11, 2004
|
||
|
|
.Dt READLINK 2
|
||
|
|
.Os
|
||
|
|
.Sh NAME
|
||
|
|
.Nm readlink
|
||
|
|
.Nd read value of a symbolic link
|
||
|
|
.Sh LIBRARY
|
||
|
|
.Lb libc
|
||
|
|
.Sh SYNOPSIS
|
||
|
|
.In unistd.h
|
||
|
|
.Ft ssize_t
|
||
|
|
.Fn readlink "const char * restrict path" "char * restrict buf" "size_t bufsiz"
|
||
|
|
.Sh DESCRIPTION
|
||
|
|
.Fn readlink
|
||
|
|
places the contents of the symbolic link
|
||
|
|
.Fa path
|
||
|
|
in the buffer
|
||
|
|
.Fa buf ,
|
||
|
|
which has size
|
||
|
|
.Fa bufsiz .
|
||
|
|
.Fn readlink
|
||
|
|
does not append a
|
||
|
|
.Dv NUL
|
||
|
|
character to
|
||
|
|
.Fa buf .
|
||
|
|
.Sh RETURN VALUES
|
||
|
|
The call returns the count of characters placed in the buffer
|
||
|
|
if it succeeds, or a \-1 if an error occurs, placing the error
|
||
|
|
code in the global variable
|
||
|
|
.Va errno .
|
||
|
|
.Sh EXAMPLES
|
||
|
|
A typical use is illustrated in the following piece of code
|
||
|
|
which reads the contents of a symbolic link named
|
||
|
|
.Pa /symbolic/link
|
||
|
|
and stores them as null-terminated string:
|
||
|
|
.Bd -literal -offset indent
|
||
|
|
#include \*[Lt]limits.h\*[Gt]
|
||
|
|
#include \*[Lt]unistd.h\*[Gt]
|
||
|
|
|
||
|
|
char buf[PATH_MAX];
|
||
|
|
ssize_t len;
|
||
|
|
|
||
|
|
if ((len = readlink("/symbolic/link", buf, sizeof(buf)-1)) == -1)
|
||
|
|
error handling;
|
||
|
|
buf[len] = '\e0';
|
||
|
|
.Ed
|
||
|
|
.Sh ERRORS
|
||
|
|
.Fn readlink
|
||
|
|
will fail if:
|
||
|
|
.Bl -tag -width Er
|
||
|
|
.It Bq Er ENOTDIR
|
||
|
|
A component of the path prefix is not a directory.
|
||
|
|
.It Bq Er ENAMETOOLONG
|
||
|
|
A component of a pathname exceeded
|
||
|
|
.Brq Dv NAME_MAX
|
||
|
|
characters, or an entire path name exceeded
|
||
|
|
.Brq Dv PATH_MAX
|
||
|
|
characters.
|
||
|
|
.It Bq Er ENOENT
|
||
|
|
The named file does not exist.
|
||
|
|
.It Bq Er EACCES
|
||
|
|
Search permission is denied for a component of the path prefix.
|
||
|
|
.It Bq Er ELOOP
|
||
|
|
Too many symbolic links were encountered in translating the pathname.
|
||
|
|
.It Bq Er EINVAL
|
||
|
|
The named file is not a symbolic link.
|
||
|
|
.It Bq Er EIO
|
||
|
|
An I/O error occurred while reading from the file system.
|
||
|
|
.It Bq Er EFAULT
|
||
|
|
.Fa buf
|
||
|
|
extends outside the process's allocated address space.
|
||
|
|
.El
|
||
|
|
.Sh SEE ALSO
|
||
|
|
.Xr lstat 2 ,
|
||
|
|
.Xr stat 2 ,
|
||
|
|
.Xr symlink 2 ,
|
||
|
|
.Xr symlink 7
|
||
|
|
.Sh STANDARDS
|
||
|
|
The
|
||
|
|
.Fn readlink
|
||
|
|
function conforms to
|
||
|
|
.St -p1003.1-2001 .
|
||
|
|
.Sh HISTORY
|
||
|
|
The
|
||
|
|
.Fn readlink
|
||
|
|
function appeared in
|
||
|
|
.Bx 4.2 .
|
||
|
|
The type returned was changed from
|
||
|
|
.Ft int
|
||
|
|
to
|
||
|
|
.Ft ssize_t
|
||
|
|
in
|
||
|
|
.Nx 2.1 .
|