Provided by: freebsd-manpages_7.1~beta1-1_all bug

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 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
                        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 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.