NAME

     VOP_LISTEXTATTR — retrieve a list of named extended attribute from a vnode

SYNOPSIS

     #include <sys/param.h>
     #include <sys/vnode.h>
     #include <sys/extattr.h>

     int
     VOP_LISTEXTATTR(struct vnode *vp, int attrnamespace, struct uio *uio, size_t *size,
         struct ucred *cred, struct thread *td);

DESCRIPTION

     This vnode call may be used to retrieve a list of named extended attributes from a specified
     namespace on 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.

     uio            The location of the data to be read.  The resulting data will be a list of
                    attribute names.  Each list entry consists of a single byte containing the
                    length of the attribute name, followed by the attribute name.  The attribute
                    name is not terminated by ASCII NUL.

     size           If not NULL, on return it will contain the number of bytes required to read
                    the list.  In most cases uio will be NULL when size is not, and vice 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 the list
     read.  Otherwise, an appropriate error code is returned.

ERRORS

     [EACCES]           The caller does not have the appropriate privilege.

     [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 namespace or uio argument is invalid.

     [EOPNOTSUPP]       The file system does not support VOP_LISTEXTATTR().

SEE ALSO

     extattr(9), vnode(9), VOP_GETEXTATTR(9), VOP_SETEXTATTR(9)