Re: [PATCH 3/7] wsdapi: Build and write Types list for Hello message.

[Huw Davies]

On Fri, Apr 20, 2018 at 08:46:23AM +0100, Huw Davies wrote:
> On Fri, Apr 20, 2018 at 08:18:19AM +0100, Owen Rudge wrote:
> > Signed-off-by: Owen Rudge 
> > +static HRESULT build_types_list(LPWSTR buffer, size_t buffer_size, const WSD_NAME_LIST *list, struct list *namespaces)
> > +{
> > - WCHAR format_string[] = { '%', 's', ':', '%', 's', ' ', 0 };
> > - LPWSTR current_buf_pos = buffer;
> > - size_t memory_needed = 0;
> > - const WSD_NAME_LIST *cur = list;
> > -
> > - ZeroMemory(buffer, buffer_size);
> > -
> > - while (cur != NULL)
> > - {
> > -
> >    /* Calculate space needed, including NULL character, colon and potential trailing space */
> > -
> >    memory_needed = sizeof(WCHAR) * (lstrlenW(cur->Element->LocalName) +
> > -
> >        lstrlenW(cur->Element->Space->PreferredPrefix) + 3);
> > -
> > -
> >    if (current_buf_pos + memory_needed > buffer + buffer_size)
> > -
> >        return E_INVALIDARG;
> > -
> > -
> >    current_buf_pos += wsprintfW(current_buf_pos, format_string, cur->Element->Space->PreferredPrefix,
> > -
> >        cur->Element->LocalName);
> > -
> > -
> >    /* Record the namespace in the discovered namespaces list */
> > -
> >    if (!add_discovered_namespace(namespaces, cur->Element->Space))
> > -
> >        return E_FAIL;
> > -
> > -
> >    cur = cur->Next;
> > - }
> > -
> > - /* Remove the last trailing space */
> > - current_buf_pos--;
> > - *current_buf_pos = 0;
>
> Is it possible that list could be NULL so that the while loop is never
> executed?  If so, then the above line would touch buffer[-1].  If
> list is never NULL consider rewriting the loop as a do-while.

And actually, thinking about it a bit more, it would most likely be
cleaner to add the space at the beginning of the loop if (cur != list).

Huw.