eba8ab0e3e
There is no reason for it to behave differently from openat(fd, NULL). Also the handling did not worked because the substituted path was from the system address space, causing EFAULT. Submitted by: Jack Halford <jack@gandi.net> MFC after: 1 week Differential revision: https://reviews.freebsd.org/D18501
238 lines
5.4 KiB
Groff
238 lines
5.4 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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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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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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.\" @(#)getfh.2 8.1 (Berkeley) 6/9/93
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.\" $FreeBSD$
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.\"
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.Dd December 11, 2018
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.Dt GETFH 2
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.Os
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.Sh NAME
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.Nm getfh ,
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.Nm lgetfh ,
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.Nm getfhat
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.Nd get file handle
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/mount.h
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.Ft int
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.Fn getfh "const char *path" "fhandle_t *fhp"
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.Ft int
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.Fn lgetfh "const char *path" "fhandle_t *fhp"
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.Ft int
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.Fn getfhat "int fd" "const char *path" "fhandle_t *fhp" "int flag"
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.Sh DESCRIPTION
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The
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.Fn getfh
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system call
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returns a file handle for the specified file or directory
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in the file handle pointed to by
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.Fa fhp .
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.Pp
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The
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.Fn lgetfh
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system call is like
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.Fn getfh
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except in the case where the named file is a symbolic link,
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in which case
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.Fn lgetfh
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returns information about the link,
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while
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.Fn getfh
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returns information about the file the link references.
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.Pp
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The
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.Fn getfhat
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system call is equivalent to
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.Fn getfh
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and
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.Fn lgetfh
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except when the
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.Fa path
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specifies a relative path, or the
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.Dv AT_BENEATH
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flag is provided.
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For
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.Fn getfhat
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and relative
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.Fa path ,
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the status is retrieved from a file relative to
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the directory associated with the file descriptor
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.Fa fd
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instead of the current working directory.
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For
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.Dv AT_BENEATH
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and absolute
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.Fa path ,
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the status is retrieved from a file specified by the
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.Fa path ,
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but additional permission checks are performed, see below.
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.Pp
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The values for the
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.Fa flag
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are constructed by a bitwise-inclusive OR of flags from this list,
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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_NOFOLLOW
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If
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.Fa path
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names a symbolic link, the status of the symbolic link is returned.
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.It Dv AT_BENEATH
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Only stat files and directories below 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 getfhat
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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 fd
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parameter, the current working directory is used and the behavior is
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identical to a call to
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.Fn getfth
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or
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.Fn lgetfh
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respectively, depending on whether or not the
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.Dv AT_SYMLINK_NOFOLLOW
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bit is set in
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.Fa flag .
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.Pp
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When
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.Fn getfhat
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is called with an absolute
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.Fa path
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without the
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.Dv AT_BENEATH
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flag, it ignores the
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.Fa fd
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argument.
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When
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.Dv AT_BENEATH
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is specified with an absolute
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.Fa path ,
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a directory passed by the
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.Fa fd
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argument is used as the topping point for the resolution.
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These system calls are restricted to the superuser.
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.Sh RETURN VALUES
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.Rv -std
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.Sh ERRORS
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The
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.Fn getfh
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and
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.Fn lgetfh
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system calls
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fail if one or more of the following are true:
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of the path prefix of
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.Fa path
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is not a directory.
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.It Bq Er ENAMETOOLONG
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The length of a component of
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.Fa path
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exceeds 255 characters,
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or the length of
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.Fa path
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exceeds 1023 characters.
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.It Bq Er ENOENT
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The file referred to by
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.Fa path
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does not exist.
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix of
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.Fa path .
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating
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.Fa path .
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.It Bq Er EFAULT
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The
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.Fa fhp
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argument
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points to an invalid address.
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.It Bq Er EFAULT
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The
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.Fa path
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argument
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points to an invalid address.
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.It Bq Er EIO
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An
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.Tn I/O
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error occurred while reading from or writing to the file system.
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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
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.Fn getfh ,
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and
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.Fn lgetfh ,
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the
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.Fn getfhat
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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 path
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argument does not specify an absolute path and the
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.Fa fd
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argument, is neither
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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 path
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argument is not an absolute path and
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.Fa fd
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is neither
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.Dv AT_FDCWD
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nor a file descriptor associated with a directory.
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.Sh SEE ALSO
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.Xr fhopen 2 ,
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.Xr open 2 ,
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.Xr stat 2
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.Sh HISTORY
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The
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.Fn getfh
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system call first appeared in
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.Bx 4.4 .
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