VOP_GETEXTATTR(9)      FreeBSD Kernel Developer's Manual     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 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 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 data read.  Otherwise, an appropriate error code is returned.

ERRORS
     [ENOATTR]          The requested attribute was not defined for this
                        vnode.

     [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 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.

FreeBSD 13.1-RELEASE-p6        December 23, 1999       FreeBSD 13.1-RELEASE-p6