VOP_GETEXTATTR(9) BSD Kernel Developer's Manual VOP_GETEXTATTR(9)NAMEVOP_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 extended
attribute from a file or directory.
Its arguments are:
vp The vnode of the file or directory.
attrnamespace Integer constant indicating which extended attribute
namespace the attribute name is present in.
name Pointer to a null-terminated character string containing
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 attribute data. In most cases
uio will be NULL when size is not, and vise versa.
cred The user credentials to use in authorizing the request.
td The thread requesting the extended attribute.
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 implementing 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 appropriate 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 ALSOextattr(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
