[poppler] Patch: Handle broken PDF causing crash

[Jan-Erik S]

On lör, 2017-07-29 at 18:25 +0200, Albert Astals Cid wrote:
> El dimarts, 4 de juliol de 2017, a les 12:07:19 CEST, Jan-Erik S va escriure:
> > Hi!
> > Here is a patch I made (against 0.54.0 - but it applies cleanly to
> > 0.56.0) to handle pdfs that use unknown type names.
> 
> Globalparams is bad, adding more stuff there is not wanted.
> 
> Also can you please explain why we should do that and ideally attach a pdf 
> that needs it?
> 
> Cheers,
>   Albert

I added the stuff to Globalparams to avoid changing default behaviour,
but the last part of this patch (StructElement.cc) is needed to be able
to handle broken PDF:s in a reasonable manner.  The StructTree is needed
to do that and the present strategy leads to it being unavailable.

I am regretfully not at liberty to distribute the pdf that triggered
this problem, but it is triggered by a pdf that use an unknown
StructElem type name without providing a mapping to something known in
RoleMap.

The patch simply provides a default mapping to the known type Part in
this situation (and produce an informative warning saying so).

Regards, Jan-Erik