vop_getextattr(9)

NAME

VOP_GETEXTATTR - retrieve named extended attribute from a

vnode

SYNOPSIS

#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/extattr.h>
int
VOP_GETEXTATTR(struct  vnode  *vp,  int attrnamespace, const
char *name,
        struct uio *uio, size_t *size, struct ucred *cred,
        struct thread *td);

DESCRIPTION

This vnode call may be used to retrieve a specific named ex

tended
attribute from a file or directory.

Its arguments are:

vp The vnode of the file or directory.

attrnamespace Integer constant indicating which extend

ed attribute

namespace the attribute name is present

in.

name Pointer to a null-terminated character

string contain

ing the attribute name.

uio The location of the data to be read.

size If not NULL, on return it will contain

the number of

bytes required to read all of the at

tribute data. In
most cases uio will be NULL when size is

not, and vise
versa.

cred The user credentials to use in authoriz

ing the

request.

td The thread requesting the extended at

tribute.

The cred pointer may be NULL to indicate that access control

checks are
not to be performed, if possible. This cred setting might

be used to
allow the kernel to authorize extended attribute retrieval

that the
active process might not be permitted to do.

Extended attribute semantics may vary by file system imple

menting the
call. More information on extended attributes may be found

in
extattr(9).

LOCKS

The vnode will be locked on entry and should remain locked

on return.

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.

ERRORS

[ENOATTR] The requested attribute was not defined

for this

vnode.

[EACCES] The the caller does not have the appro

priate privi

lege.

[ENXIO] The request was not valid in this file

system for the

specified vnode and attribute name.

[ENOMEM] Sufficient memory is not available to

fulfill the

request.

[EFAULT] The uio structure refers to an invalid

userspace

address.

[EINVAL] The name, namespace, or uio argument is

invalid.

[EOPNOTSUPP] The file system does not support

VOP_GETEXTATTR

SEE ALSO

extattr(9), vnode(9), VOP_LISTEXTATTR(9), VOP_SETEXTATTR(9)

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.

BSD December 23, 1999

BSD