Re: [DTC PATCH] libfdt: Add ft_get_next_node(), ft_get_next_prop(), and ft_getprop_offset().

[David Gibson <david@gibson.dropbear.id.au>]

On Tue, Jan 15, 2008 at 10:52:30AM -0600, Scott Wood wrote:
> On Tue, Jan 15, 2008 at 11:16:57AM +1100, David Gibson wrote:
> > On Mon, Jan 14, 2008 at 10:30:04AM -0600, Scott Wood wrote:
> > > ft_get_next_node() enumerates children of a given node.
> > > ft_get_next_prop() enumerates propreties of a given node.
> > > 
> > > ft_getprop_offset() is like ft_getprop(), but takes a property offset rather
> > > than a node offset and property name; it is primarily intended for use
> > > with ft_get_next_prop().
> > 
> > Urg... this kind of serves me right for not getting my act together on
> > iterator functions yet.  I really don't like this approach much.  I'll
> > see if I can come up with something I prefer this afternoon.
> 
> OK.
> 
> > The biggest thing I dislike is that I've deliberately avoided having
> > any offsets-to-properties exposed to the library user.  That's because
> > the whole offsets change when you write the tree problem is worse for
> > properties than nodes (in that likely idiomatic uses will be bitten by
> > changes in property offsets).
> 
> We can drop the property iteration for now; I wrote it for an attempt at
> node merging which I postponed.

Heh.. and I spent most of yesterday working on a counter-proposal for
property iteration.  Oh well, let's leave this for now and look at the
node iteration first.

> > > +	if (depth != 0)
> > > +		return -FDT_ERR_BADSTRUCTURE;
> > 
> > I think this should be FDT_ERR_TRUNCATED.
> 
> I'd expect TRUNCATED when we hit totalsize without an FDT_END, not when
> we hit FDT_END in an inappropriate context.

Well, TRUNCATED is valid for either situation, and fdt_next_tag() also
returns FDT_END if it reaches totalsize.

> > > +	return -FDT_ERR_NOTFOUND;
> > 
> > In fact, so should this.  This function should never actually reach
> > the FDT_END tag.
> 
> No, it's valid if you're iterating over all nodes (node -1, depth
> -1).

Uh.. yeah, I guess so.

> > > +#define FDT_ERR_BADDEPTH	8
> > > +	/* FDT_ERR_BADDEPTH: Function was passed a negative
> > > +	 * (or otherwise invalid) depth. */
> > 
> > You've added this error code, but you don't actually return it
> > anywhere...
> 
> Oops, it must have been from the aforementioned node merging code, and I
> thought it was from fdt_get_next_node when splitting things up.

Ok.

> > This description is incorrect - you've copied the fdt_getprop()
> > description and forgotten to update it.
> 
> /me hides in shame

:)

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson