1.\"- 2.\" Copyright (c) 1999, 2000, 2001, 2003 Robert N. M. Watson 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd December 23, 1999 29.Dt VOP_GETEXTATTR 9 30.Os 31.Sh NAME 32.Nm VOP_GETEXTATTR 33.Nd retrieve named extended attribute from a vnode 34.Sh SYNOPSIS 35.In sys/param.h 36.In sys/vnode.h 37.In sys/extattr.h 38.Ft int 39.Fo VOP_GETEXTATTR 40.Fa "struct vnode *vp" 41.Fa "int attrnamespace" 42.Fa "const char *name" 43.Fa "struct uio *uio" 44.Fa "size_t *size" 45.Fa "struct ucred *cred" 46.Fa "struct thread *td" 47.Fc 48.Sh DESCRIPTION 49This vnode call may be used to retrieve a specific named extended attribute 50from a file or directory. 51.Pp 52Its arguments are: 53.Bl -tag -width ".Fa attrnamespace" 54.It Fa vp 55The vnode of the file or directory. 56.It Fa attrnamespace 57Integer constant indicating which extended attribute namespace the attribute 58name is present in. 59.It Fa name 60Pointer to a null-terminated character string containing the attribute name. 61.It Fa uio 62The location of the data to be read. 63.It Fa size 64If not 65.Dv NULL , 66on return it will contain the number of bytes required to read all of the 67attribute data. 68In most cases 69.Fa uio 70will be 71.Dv NULL 72when 73.Fa size 74is not, and vice versa. 75.It Fa cred 76The user credentials to use in authorizing the request. 77.It Fa td 78The thread requesting the extended attribute. 79.El 80.Pp 81The 82.Fa cred 83pointer may be 84.Dv NULL 85to indicate that access control checks are not to be performed, if possible. 86This 87.Fa cred 88setting might be used to allow the kernel to authorize extended attribute 89retrieval that the active process might not be permitted to do. 90.Pp 91Extended attribute semantics may vary by file system implementing the call. 92More information on extended attributes may be found in 93.Xr extattr 9 . 94.Sh LOCKS 95The vnode will be locked on entry and should remain locked on return. 96.Sh RETURN VALUES 97On success, zero will be returned, and the uio structure will be updated to 98reflect data read. 99Otherwise, an appropriate error code is returned. 100.Sh ERRORS 101.Bl -tag -width Er 102.It Bq Er ENOATTR 103The requested attribute was not defined for this vnode. 104.It Bq Er EACCES 105The caller does not have the appropriate privilege. 106.It Bq Er ENXIO 107The request was not valid in this file system for the specified vnode and 108attribute name. 109.It Bq Er ENOMEM 110Sufficient memory is not available to fulfill the request. 111.It Bq Er EFAULT 112The uio structure refers to an invalid userspace address. 113.It Bq Er EINVAL 114The 115.Fa name , 116.Fa namespace , 117or 118.Fa uio 119argument is invalid. 120.It Bq Er EOPNOTSUPP 121The file system does not support 122.Fn VOP_GETEXTATTR . 123.El 124.Sh SEE ALSO 125.Xr extattr 9 , 126.Xr vnode 9 , 127.Xr VOP_LISTEXTATTR 9 , 128.Xr VOP_SETEXTATTR 9 129.Sh BUGS 130By passing in the empty string as the attribute name, some file systems 131will return a list of defined names on the target vnode for the 132requested namespace. 133This is a bad API, and will be replaced by an explicit VOP. 134