[PATCH v2] dwrite: Do not segfault when there are no typographic features to return.

[Nikolay Sivov]

On 3/3/21 4:35 PM, Giovanni Mascellani wrote:
> Signed-off-by: Giovanni Mascellani <gmascellani at codeweavers.com>
> ---
>  dlls/dwrite/shape.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/dlls/dwrite/shape.c b/dlls/dwrite/shape.c
> index 6428bf6ceb0..809e66ebedb 100644
> --- a/dlls/dwrite/shape.c
> +++ b/dlls/dwrite/shape.c
> @@ -372,6 +372,14 @@ HRESULT shape_get_typographic_features(struct scriptshaping_context *context, co
>      shape_get_script_lang_index(context, scripts, MS_GPOS_TAG, &script_index, &language_index);
>      opentype_get_typographic_features(&context->cache->gpos, script_index, language_index, &t);
>  
> +    /* Return immediately if there are not features, because the
> +       duplicate removal algorithm doesn't like an empty array. */
> +    if (t.count == 0)
> +    {
> +        heap_free(t.tags);
> +        return S_OK;
> +    }
> +
>      /* Sort and remove duplicates. */
>      qsort(t.tags, t.count, sizeof(*t.tags), tag_array_sorting_compare);
>  
Out argument is not set; 'tags' would be null if count is 0; comment is
unnecessary, it's pretty obvious what's going on.