Re: [xml] "double"s and schema validation

["Andrew W. Nosenko" <andrew w nosenko gmail com>]

On Wed, Jul 21, 2010 at 14:23, Csaba Raduly <rcsaba gmail com> wrote:
> On Tue, Jul 20, 2010 at 3:40 AM, Dan Sommers  wrote:
> > Given this schema file, t.xsd:
> >
> >    <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";>
> >      <xs:element name="t" type="xs:double"/>
> >    </xs:schema>
> >
> > And this xml document, t.xml:
> >
> >    <t>e</t>
> >
> > I got this:
> >
> >    $ xmllint --schema t.xsd t.xml
> >    <?xml version="1.0"?>
> >    <t>e</t>
> >    t.xml validates
> >
> > Note that <t>.</t> and <t>.e</t> also validate.
> >
> > I tracked it down to xmlschematypes.c, starting around line 2465, where
> > it starts scanning the input for something suitable for sscanf("%lf").
> > Should that code contain an extra check that there is at least one digit
> > somewhere?
>
> I think you are right. This code:
>                while ((*cur >= '0') && (*cur <= '9')) {
>                    cur++;
>                }
> accepts 0 or more digits (before the period); perhaps it should check
> for 1 or more digits instead:

No!  The case like ".5" instead of "0.5" is perfectly valid and widely used!
Whether the "." or "e" are valid string representation of the "double"
type or should be rejected -- it's another matter.  But zero digits
before dot are absolutely correct and should be allowed.

-- 
Andrew W. Nosenko <andrew w nosenko gmail com>