func (c *FileSystemConnector) Lookup(out *raw.EntryOut, header *raw.InHeader, name string) (code Status) {
	parent := c.toInode(header.NodeId)
	if !parent.IsDir() {
		log.Printf("Lookup %q called on non-Directory node %d", name, header.NodeId)
		return ENOTDIR
	}
	context := (*Context)(&header.Context)
	outAttr := (*Attr)(&out.Attr)
	child, code := c.internalLookup(outAttr, parent, name, context)
	if code == ENOENT && parent.mount.negativeEntry(out) {
		return OK
	}
	if !code.Ok() {
		return code
	}
	if child == nil {
		log.Println("Lookup returned OK with nil child", name)
	}

	child.mount.fillEntry(out)
	out.NodeId = c.lookupUpdate(child)
	out.Generation = child.generation
	out.Ino = out.NodeId

	return OK
}

// Generate EntryOut and increase the lookup count for an inode.
func (c *FileSystemConnector) childLookup(out *raw.EntryOut, fsi FsNode) {
	n := fsi.Inode()
	fsi.GetAttr((*Attr)(&out.Attr), nil, nil)
	n.mount.fillEntry(out)
	out.Ino = c.lookupUpdate(n)
	out.NodeId = out.Ino
	if out.Nlink == 0 {
		// With Nlink == 0, newer kernels will refuse link
		// operations.
		out.Nlink = 1
	}
}

func (m *fileSystemMount) fillEntry(out *raw.EntryOut) {
	splitDuration(m.options.EntryTimeout, &out.EntryValid, &out.EntryValidNsec)
	splitDuration(m.options.AttrTimeout, &out.AttrValid, &out.AttrValidNsec)
	m.setOwner(&out.Attr)
	if out.Mode&S_IFDIR == 0 && out.Nlink == 0 {
		out.Nlink = 1
	}
}

// Creates a return entry for a non-existent path.
func (m *fileSystemMount) negativeEntry(out *raw.EntryOut) bool {
	if m.options.NegativeTimeout > 0.0 {
		out.NodeId = 0
		splitDuration(m.options.NegativeTimeout, &out.EntryValid, &out.EntryValidNsec)
		return true
	}
	return false
}