[poppler] Big image splash support

[Martin (gzlist)]

On Thu, 1 Oct 2020 at 23:48, Albert Astals Cid <aacid at kde.org> wrote:
>
> If it's guarded, it's not wrong.
>
> It's like saying that code this code
>
> if (!a)
>   return;
>
> a->doSomething();
>
> is technically wrong because if a is null it will crash and is only guarded by the if.
>
> Yes, that's what guards do, they make subsequent code free to assume stuff.

The issue is the guard is distant from all the rest of the code
depending on it. At the moment there are lots of methods with implicit
preconditions, some obvious (height is greater than zero), others less
so (width times components_of_mode plus row_pad times height is less
than some_large_number). It's just easier to work with code that is
trivially correct due to the types and operations being used, and the
compiler does more verification for you.

> Make the patches correct (to by possibly wrong perception).

Rather than make the prerequisite patches pointless, I've put up the
full set in a PR that you can build and try. You can also try removing
the type casts you don't see the reason for, and see where the program
then segfaults.

https://gitlab.freedesktop.org/poppler/poppler/-/merge_requests/645

Thanks,

Martin