d1fd400a80
Namely, getfhat(2), fhlink(2), fhlinkat(2), fhreadlink(2). The syscalls are provided for a NFS userspace server (nfs-ganesha). Submitted by: Jack Halford <jack@gandi.net> Sponsored by: Gandi.net Tested by: pho Feedback from: brooks, markj MFC after: 1 week Differential revision: https://reviews.freebsd.org/D18359
269 lines
6.0 KiB
Groff
269 lines
6.0 KiB
Groff
.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2018 Gandi
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 29, 2018
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.Dt FHLINK 2
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.Os
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.Sh NAME
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.Nm fhlink ,
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.Nm fhlinkat
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.Nd make a hard file link
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft int
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.Fn fhlink "fhandle_t *fhp" "const char *to"
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.Ft int
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.Fn fhlinkat "fhandle_t *fhp" "int tofd" "const char *to"
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.Fc
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.Sh DESCRIPTION
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The
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.Fn fhlink
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system call
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atomically creates the specified directory entry (hard link)
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.Fa to
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with the attributes of the underlying object pointed at by
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.Fa fhp .
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If the link is successful: the link count of the underlying object
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is incremented;
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.Fa fhp
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and
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.Fa to
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share equal access and rights
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to the
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underlying object.
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.Pp
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If
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.Fa fhp
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is removed, the file
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.Fa to
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is not deleted and the link count of the
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underlying object is
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decremented.
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.Pp
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The object pointed at by the
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.Fa fhp
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argument
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must exist for the hard link to
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succeed and
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both
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.Fa fhp
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and
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.Fa to
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must be in the same file system.
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The
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.Fa fhp
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argument
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may not be a directory.
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.Pp
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The
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.Fn fhlinkat
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system call is equivalent to
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.Fa fhlink
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except in the case where
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.Fa to
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is a relative paths.
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In this case a relative path
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.Fa to
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is interpreted relative to
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the directory associated with the file descriptor
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.Fa tofd
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instead of the current working directory.
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.Pp
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Values for
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.Fa flag
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are constructed by a bitwise-inclusive OR of flags from the following
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list, defined in
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.In fcntl.h :
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.Bl -tag -width indent
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.It Dv AT_SYMLINK_FOLLOW
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If
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.Fa fhp
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names a symbolic link, a new link for the target of the symbolic link is
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created.
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.It Dv AT_BENEATH
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Only allow to link to a file which is beneath of the topping directory.
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See the description of the
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.Dv O_BENEATH
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flag in the
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.Xr open 2
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manual page.
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.El
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.Pp
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If
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.Fn fhlinkat
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is passed the special value
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.Dv AT_FDCWD
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in the
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.Fa tofd
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parameter, the current working directory is used for the
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.Fa to
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argument.
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If
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.Fa tofd
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has value
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.Dv AT_FDCWD ,
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the behavior is identical to a call to
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.Fn link .
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Unless
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.Fa flag
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contains the
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.Dv AT_SYMLINK_FOLLOW
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flag, if
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.Fa fhp
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names a symbolic link, a new link is created for the symbolic link
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.Fa fhp
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and not its target.
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.Sh RETURN VALUES
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.Rv -std link
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.Sh ERRORS
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The
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.Fn fhlink
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system call
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will fail and no link will be created if:
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of
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.Fa to
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prefix is not a directory.
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.It Bq Er ENAMETOOLONG
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A component of
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.Fa to
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exceeded 255 characters,
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or entire length of
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.Fa to
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name exceeded 1023 characters.
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.It Bq Er ENOENT
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A component of
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.Fa to
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prefix does not exist.
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.It Bq Er EOPNOTSUPP
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The file system containing the file pointed at by
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.Fa fhp
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does not support links.
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.It Bq Er EMLINK
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The link count of the file pointed at by
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.Fa fhp
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would exceed 32767.
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.It Bq Er EACCES
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A component of
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.Fa to
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prefix denies search permission.
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.It Bq Er EACCES
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The requested link requires writing in a directory with a mode
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that denies write permission.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating one of the pathnames.
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.It Bq Er ENOENT
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The file pointed at by
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.Fa fhp
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does not exist.
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.It Bq Er EEXIST
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The link named by
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.Fa to
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does exist.
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.It Bq Er EPERM
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The file pointed at by
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.Fa fhp
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is a directory.
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.It Bq Er EPERM
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The file pointed at by
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.Fa fhp
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has its immutable or append-only flag set, see the
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.Xr chflags 2
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manual page for more information.
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.It Bq Er EPERM
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The parent directory of the file named by
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.Fa to
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has its immutable flag set.
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.It Bq Er EXDEV
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The link named by
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.Fa to
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and the file pointed at by
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.Fa fhp
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are on different file systems.
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.It Bq Er ENOSPC
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The directory in which the entry for the new link is being placed
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cannot be extended because there is no space left on the file
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system containing the directory.
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.It Bq Er EDQUOT
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The directory in which the entry for the new link
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is being placed cannot be extended because the
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user's quota of disk blocks on the file system
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containing the directory has been exhausted.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to
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the file system to make the directory entry.
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.It Bq Er EROFS
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The requested link requires writing in a directory on a read-only file
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system.
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.It Bq Er EFAULT
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One of the pathnames specified
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is outside the process's allocated address space.
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.It Bq Er ESTALE
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The file handle
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.Fa fhp
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is no longer valid
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.El
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.Pp
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In addition to the errors returned by the
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.Fn fhlink ,
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the
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.Fn fhlinkat
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system call may fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa fhp
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or
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.Fa to
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argument does not specify an absolute path and the
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.Fa tofd
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argument, is not
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.Dv AT_FDCWD
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nor a valid file descriptor open for searching.
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.It Bq Er EINVAL
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The value of the
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.Fa flag
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argument is not valid.
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.It Bq Er ENOTDIR
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The
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.Fa fhp
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or
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.Fa to
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argument is not an absolute path and
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.Fa tofd
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is not
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.Dv AT_FDCWD
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nor a file descriptor associated with a directory.
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.El
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.Sh SEE ALSO
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.Xr fhstat 2 ,
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.Xr fhreadlink 2 ,
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.Xr fhopen 2 ,
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