freebsd-skq/share/man/man9/VOP_GETEXTATTR.9

.\"-
.\" Copyright (c) 1999, 2000, 2001, 2003 Robert N. M. Watson
.\" 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
.\"
.\" $FreeBSD$
.\"
.Dd December 23, 1999
.Dt VOP_GETEXTATTR 9
.Os
.Sh NAME
.Nm VOP_GETEXTATTR
.Nd retrieve named extended attribute from a vnode
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.In sys/extattr.h
.Ft int
.Fo VOP_GETEXTATTR
.Fa "struct vnode *vp"
.Fa "int attrnamespace"
.Fa "const char *name"
.Fa "struct uio *uio"
.Fa "size_t *size"
.Fa "struct ucred *cred"
.Fa "struct thread *td"
.Fc
.Sh DESCRIPTION
This vnode call may be used to retrieve a specific named extended attribute
from a file or directory.
.Pp
Its arguments are:
.Bl -tag -width ".Fa attrnamespace"
.It Fa vp
The vnode of the file or directory.
.It Fa attrnamespace
Integer constant indicating which extended attribute namespace the attribute
name is present in.
.It Fa name
Pointer to a null-terminated character string containing the attribute name.
.It Fa uio
The location of the data to be read.
.It Fa size
If not
.Dv NULL ,
on return it will contain the number of bytes required to read all of the
attribute data.
In most cases
.Fa uio
will be
.Dv NULL
when
.Fa size
is not, and vice versa.
.It Fa cred
The user credentials to use in authorizing the request.
.It Fa td
The thread requesting the extended attribute.
.El
.Pp
The
.Fa cred
pointer may be
.Dv NULL
to indicate that access control checks are not to be performed, if possible.
This
.Fa cred
setting might be used to allow the kernel to authorize extended attribute
retrieval that the active process might not be permitted to do.
.Pp
Extended attribute semantics may vary by file system implementing the call.
More information on extended attributes may be found in
.Xr extattr 9 .
.Sh LOCKS
The vnode will be locked on entry and should remain locked on return.
.Sh RETURN VALUES
On success, zero will be returned, and the uio structure will be updated to
reflect data read.
Otherwise, an appropriate error code is returned.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ENOATTR
The requested attribute was not defined for this vnode.
.It Bq Er EACCES
The caller does not have the appropriate privilege.
.It Bq Er ENXIO
The request was not valid in this file system for the specified vnode and
attribute name.
.It Bq Er ENOMEM
Sufficient memory is not available to fulfill the request.
.It Bq Er EFAULT
The uio structure refers to an invalid userspace address.
.It Bq Er EINVAL
The
.Fa name ,
.Fa namespace ,
or
.Fa uio
argument is invalid.
.It Bq Er EOPNOTSUPP
The file system does not support
.Fn VOP_GETEXTATTR .
.El
.Sh SEE ALSO
.Xr extattr 9 ,
.Xr vnode 9 ,
.Xr VOP_LISTEXTATTR 9 ,
.Xr VOP_SETEXTATTR 9
.Sh BUGS
By passing in the empty string as the attribute name, some file systems
will return a list of defined names on the target vnode for the
requested namespace.
This is a bad API, and will be replaced by an explicit VOP.
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.\"-`
Document the BUG (feature) that you can pass in an empty name to VOP_GETEXTATTR() to retrieve the attribute name list on some file systems, and note that this will be replaced with its own VOP in due course. Pointed out by: Dominic Giampaolo <dbg@apple.com> 2003-06-04 04:03:58 +00:00			`.\" Copyright (c) 1999, 2000, 2001, 2003 Robert N. M. Watson`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.\" 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.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.`
			`.\"`
o Update some of the kernel man pages associated with extended attributes to reflect EA API change to explicit namespacing. Obtained from: TrustedBSD Project 2001-03-15 03:13:58 +00:00			`.\" $FreeBSD$`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.\"`
			`.Dd December 23, 1999`
			`.Dt VOP_GETEXTATTR 9`
mdoc: order prologue macros consistently by Dd/Dt/Os Although groff_mdoc(7) gives another impression, this is the ordering most widely used and also required by mdocml/mandoc. Reviewed by: ru Approved by: philip, ed (mentors) 2010-04-14 19:08:06 +00:00			`.Os`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.Sh NAME`
			`.Nm VOP_GETEXTATTR`
mdoc(7) police: normalize .Nd. 2001-04-18 15:54:10 +00:00			`.Nd retrieve named extended attribute from a vnode`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.Sh SYNOPSIS`
mdoc(7) police: Use the new .In macro for #include statements. 2001-10-01 16:09:29 +00:00			`.In sys/param.h`
			`.In sys/vnode.h`
			`.In sys/extattr.h`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.Ft int`
Document the new size parameter. 2002-04-12 04:26:15 +00:00			`.Fo VOP_GETEXTATTR`
			`.Fa "struct vnode *vp"`
			`.Fa "int attrnamespace"`
			`.Fa "const char *name"`
			`.Fa "struct uio *uio"`
			`.Fa "size_t *size"`
			`.Fa "struct ucred *cred"`
			`.Fa "struct thread *td"`
			`.Fc`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.Sh DESCRIPTION`
			`This vnode call may be used to retrieve a specific named extended attribute`
			`from a file or directory.`
			`.Pp`
			`Its arguments are:`
Document the new size parameter. 2002-04-12 04:26:15 +00:00			`.Bl -tag -width ".Fa attrnamespace"`
o The mdoc(7) police strike with avengance: - These pages abused Ar macro (they should have used Fa). - NULL constant should be marked with Dv. - VOP_* in the ERRORS section for the EOPNOTSUPP entry should be marked with Fn. Submitted by: ru 2001-03-16 15:02:30 +00:00			`.It Fa vp`
Mark lists as in the rest of section 9 manpages. Submitted by: Joel Dahl (mostly) 2005-01-28 10:43:05 +00:00			`The vnode of the file or directory.`
Some mdoc(7) fixes: Nuke incorrect usage of .Ar; replace it with .Vt, .Va or .Fa appropriately. The .Ar mdoc(7) specifier should only be used when displaying command line arguments. Approved by: des (mentor) 2003-05-31 14:07:25 +00:00			`.It Fa attrnamespace`
Mark lists as in the rest of section 9 manpages. Submitted by: Joel Dahl (mostly) 2005-01-28 10:43:05 +00:00			`Integer constant indicating which extended attribute namespace the attribute`
			`name is present in.`
o The mdoc(7) police strike with avengance: - These pages abused Ar macro (they should have used Fa). - NULL constant should be marked with Dv. - VOP_* in the ERRORS section for the EOPNOTSUPP entry should be marked with Fn. Submitted by: ru 2001-03-16 15:02:30 +00:00			`.It Fa name`
Mark lists as in the rest of section 9 manpages. Submitted by: Joel Dahl (mostly) 2005-01-28 10:43:05 +00:00			`Pointer to a null-terminated character string containing the attribute name.`
o The mdoc(7) police strike with avengance: - These pages abused Ar macro (they should have used Fa). - NULL constant should be marked with Dv. - VOP_* in the ERRORS section for the EOPNOTSUPP entry should be marked with Fn. Submitted by: ru 2001-03-16 15:02:30 +00:00			`.It Fa uio`
Mark lists as in the rest of section 9 manpages. Submitted by: Joel Dahl (mostly) 2005-01-28 10:43:05 +00:00			`The location of the data to be read.`
Document the new size parameter. 2002-04-12 04:26:15 +00:00			`.It Fa size`
Mark lists as in the rest of section 9 manpages. Submitted by: Joel Dahl (mostly) 2005-01-28 10:43:05 +00:00			`If not`
Document the new size parameter. 2002-04-12 04:26:15 +00:00			`.Dv NULL ,`
			`on return it will contain the number of bytes required to read all of the`
			`attribute data.`
			`In most cases`
			`.Fa uio`
			`will be`
			`.Dv NULL`
			`when`
			`.Fa size`
Typo and mdoc(7) style fixes. PR: 168117 Submitted by: Nobuyuki Koganemaru (kogane&jp!freebsd!org) MFC after: 3 days 2012-05-20 16:43:47 +00:00			`is not, and vice versa.`
o The mdoc(7) police strike with avengance: - These pages abused Ar macro (they should have used Fa). - NULL constant should be marked with Dv. - VOP_* in the ERRORS section for the EOPNOTSUPP entry should be marked with Fn. Submitted by: ru 2001-03-16 15:02:30 +00:00			`.It Fa cred`
Mark lists as in the rest of section 9 manpages. Submitted by: Joel Dahl (mostly) 2005-01-28 10:43:05 +00:00			`The user credentials to use in authorizing the request.`
- Fix a number of man pages broken by the KSE merger. 2001-11-20 18:19:19 +00:00			`.It Fa td`
Mark lists as in the rest of section 9 manpages. Submitted by: Joel Dahl (mostly) 2005-01-28 10:43:05 +00:00			`The thread requesting the extended attribute.`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.El`
			`.Pp`
			`The`
			`.Fa cred`
o The mdoc(7) police strike with avengance: - These pages abused Ar macro (they should have used Fa). - NULL constant should be marked with Dv. - VOP_* in the ERRORS section for the EOPNOTSUPP entry should be marked with Fn. Submitted by: ru 2001-03-16 15:02:30 +00:00			`pointer may be`
			`.Dv NULL`
			`to indicate that access control checks are not to be performed, if possible.`
			`This`
o Update some of the kernel man pages associated with extended attributes to reflect EA API change to explicit namespacing. Obtained from: TrustedBSD Project 2001-03-15 03:13:58 +00:00			`.Fa cred`
			`setting might be used to allow the kernel to authorize extended attribute`
			`retrieval that the active process might not be permitted to do.`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.Pp`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`Extended attribute semantics may vary by file system implementing the call.`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`More information on extended attributes may be found in`
			`.Xr extattr 9 .`
			`.Sh LOCKS`
o Bring VOP_GETACL(9) and VOP_GETEXTATTR(9) man page "LOCKS" sections in sync with the implementation. Vnode locks are required for these operations, as some underlying implementations will require them. Obtained from: TrustedBSD Project 2000-09-21 18:51:48 +00:00			`The vnode will be locked on entry and should remain locked on return.`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.Sh RETURN VALUES`
			`On success, zero will be returned, and the uio structure will be updated to`
Mdoc Janitor: * Fix hard sentence breaks in VFS_(9) and VOP_(9) manual pages. 2003-10-23 02:11:14 +00:00			`reflect data read.`
			`Otherwise, an appropriate error code is returned.`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.Sh ERRORS`
			`.Bl -tag -width Er`
ENOATTR is now used for error returns indicating an undefined extended attribute. EINVAL can also reflect an invalid namespace for either a get or set operation on EAs. Obtained from: TrustedBSD Project Sponsored by: DARPA, Network Associates Laboratories 2003-06-05 13:42:37 +00:00			`.It Bq Er ENOATTR`
			`The requested attribute was not defined for this vnode.`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.It Bq Er EACCES`
Remove duplicate words in mdoc(7) pages. PR: 167810 Submitted by: Bryan Drewery {bryan!shatow%net} (hackers lounge) Found with: textproc/igor MFC after: 3 days 2012-05-12 03:46:43 +00:00			`The caller does not have the appropriate privilege.`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.It Bq Er ENXIO`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`The request was not valid in this file system for the specified vnode and`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`attribute name.`
			`.It Bq Er ENOMEM`
Convert descriptions in the ERRORS section to full sentences if they were not full sentences, elaborating as necessary. 2002-09-18 22:12:43 +00:00			`Sufficient memory is not available to fulfill the request.`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.It Bq Er EFAULT`
			`The uio structure refers to an invalid userspace address.`
			`.It Bq Er EINVAL`
Removed whitespace at end-of-line; no content changes. I simply did cd src/share; find man[1-9] -type f\|xargs perl -pi -e 's/[ \t]+$//' BTW, what editors are the culprits? I'm using vim and it shows me whitespace at EOL in troff files with a thick blue block... Reviewed by: Silence from cvs diff -b MFC after: 7 days 2001-07-14 19:41:16 +00:00			`The`
ENOATTR is now used for error returns indicating an undefined extended attribute. EINVAL can also reflect an invalid namespace for either a get or set operation on EAs. Obtained from: TrustedBSD Project Sponsored by: DARPA, Network Associates Laboratories 2003-06-05 13:42:37 +00:00			`.Fa name ,`
Typo and mdoc(7) style fixes. PR: 168117 Submitted by: Nobuyuki Koganemaru (kogane&jp!freebsd!org) MFC after: 3 days 2012-05-20 16:43:47 +00:00			`.Fa namespace ,`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`or`
			`.Fa uio`
			`argument is invalid.`
			`.It Bq Er EOPNOTSUPP`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`The file system does not support`
Style and markup changes only. Capitalize the first letter of the descriptions for the entries in the ERRORS section if they are complete sentences and end the sentences with periods. 2002-09-18 09:34:01 +00:00			`.Fn VOP_GETEXTATTR .`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.El`
			`.Sh SEE ALSO`
			`.Xr extattr 9 ,`
			`.Xr vnode 9 ,`
mdoc(7): Fix common mistakes made in the SEE ALSO section. 2003-09-12 21:54:11 +00:00			`.Xr VOP_LISTEXTATTR 9 ,`
Man pages for the VFS extended attribute and access control list vnops. Reviewed by: eivind 2000-01-05 04:59:02 +00:00			`.Xr VOP_SETEXTATTR 9`
Document the BUG (feature) that you can pass in an empty name to VOP_GETEXTATTR() to retrieve the attribute name list on some file systems, and note that this will be replaced with its own VOP in due course. Pointed out by: Dominic Giampaolo <dbg@apple.com> 2003-06-04 04:03:58 +00:00			`.Sh BUGS`
			`By passing in the empty string as the attribute name, some file systems`
			`will return a list of defined names on the target vnode for the`
			`requested namespace.`
			`This is a bad API, and will be replaced by an explicit VOP.`