webservices: allocate enough memory for WS_XML_TEXT_TYPE_DOUBLE (Valgrind) (try 2)

[Hans Leidekker]

On Wed, 2016-12-21 at 09:38 +0100, Alexandre Julliard wrote:
> Austin English <austinenglish at gmail.com> writes:
> 
> > On Wed, Dec 14, 2016 at 4:45 PM, Marvin <testbot at winehq.org> wrote:
> >> Thank you for your contribution to Wine!
> >>
> >> This is an automated notification to let you know that your patch has
> >> been reviewed and its status set to "Assigned".
> >>
> >> This means that the patch has been assigned to a reviewer. If the
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> >> after a couple of weeks, please resend the patch.
> >
> > This shows in the tracker as assigned to Hans, but Hans signed off a week ago.
> 
> Henri objected, and I agree, that we need to understand what's going on,
> and in particular why 48 would be the correct size.

Valgrind ignores the rounding mode:

Valgrind, setting RC_DOWN:
writer.c:364: Test failed: 2097: got 39 expected 22
writer.c:366: Test failed: 2097: got <t>100000000000000.0156249999999999</t> expected <t>100000000000000</t>

no Valgrind, not setting RC_DOWN:
writer.c:364: Test failed: 2097: got 39 expected 22
writer.c:366: Test failed: 2097: got <t>100000000000000.0312499999999999</t> expected <t>100000000000000</t>

32 characters will be needed at most (excluding XML tags) because the
formatting code switches to exponential notation beyond 1^14 and precision
is capped at 0.0000000000000001, or 16 digits.