mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-25 11:37:56 +00:00
159 lines
4.2 KiB
Groff
159 lines
4.2 KiB
Groff
.\" 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.
|
|
.\" 4. 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
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd April 10, 2008
|
|
.Dt READLINK 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm readlink ,
|
|
.Nm readlinkat
|
|
.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"
|
|
.Ft ssize_t
|
|
.Fo readlinkat
|
|
.Fa "int fd" "const char *restrict path" "char *restrict buf" "size_t bufsize"
|
|
.Fc
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn readlink
|
|
system call
|
|
places the contents of the symbolic link
|
|
.Fa path
|
|
in the buffer
|
|
.Fa buf ,
|
|
which has size
|
|
.Fa bufsiz .
|
|
The
|
|
.Fn readlink
|
|
system call does not append a
|
|
.Dv NUL
|
|
character to
|
|
.Fa buf .
|
|
.Pp
|
|
The
|
|
.Fn readlinkat
|
|
system call is equivalent to
|
|
.Fn readlink
|
|
except in the case where
|
|
.Fa path
|
|
specifies a relative path.
|
|
In this case the symbolic link whose content is read relative to the
|
|
directory associated with the file descriptor
|
|
.Fa fd
|
|
instead of the current working directory.
|
|
If
|
|
.Fn readlinkat
|
|
is passed the special value
|
|
.Dv AT_FDCWD
|
|
in the
|
|
.Fa fd
|
|
parameter, the current working directory is used and the behavior is
|
|
identical to a call to
|
|
.Fn readlink .
|
|
.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 ERRORS
|
|
The
|
|
.Fn readlink
|
|
system call
|
|
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 255 characters,
|
|
or an entire path name exceeded 1023 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
|
|
The
|
|
.Fa buf
|
|
argument
|
|
extends outside the process's allocated address space.
|
|
.El
|
|
.Pp
|
|
In addition to the errors returned by the
|
|
.Fn readlink ,
|
|
the
|
|
.Fn readlinkat
|
|
may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The
|
|
.Fa path
|
|
argument does not specify an absolute path and the
|
|
.Fa fd
|
|
argument is neither
|
|
.Dv AT_FDCWD
|
|
nor a valid file descriptor open for searching.
|
|
.It Bq Er ENOTDIR
|
|
The
|
|
.Fa path
|
|
argument is not an absolute path and
|
|
.Fa fd
|
|
is neither
|
|
.Dv AT_FDCWD
|
|
nor a file descriptor associated with a directory.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr lstat 2 ,
|
|
.Xr stat 2 ,
|
|
.Xr symlink 2 ,
|
|
.Xr symlink 7
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn readlinkat
|
|
system call follows The Open Group Extended API Set 2 specification.
|
|
.Sh HISTORY
|
|
The
|
|
.Fn readlink
|
|
system call appeared in
|
|
.Bx 4.2 .
|
|
The
|
|
.Fn readlinkat
|
|
system call appeared in
|
|
.Fx 8.0 .
|