rem: struct devfs *fs = _fs;
context: devfs_open(fs_volume _fs, fs_vnode _v, int oflags, fs_cookie *_cookie){	struct devfs *fs = _fs;	struct devfs_vnode *vnode = _v;	struct devfs_cookie *cookie;	status_t status = 0;	TRACE(("devfs_open: fs_cookie %p vnode %p, oflags 0x%x, fs_cookie %p \n", fs, vnode, oflags, _cookie));	cookie = malloc(sizeof(struct devfs_cookie));	if (cookie == NULL)		return ENOMEM;	if (vnode->stream.type != STREAM_TYPE_DEVICE)		return EINVAL;	status = vnode->stream.u.dev.ops->open(vnode->name, oflags, &cookie->u.dev.dcookie);	*_cookie = cookie;	return status;}