Re: possible issue with ps2pdf (9.25) and transparency

Sorry Ken, thanks for the explanation and apologies for not being able to
read.
-p


On September 15, 2018 at 9:36:00 PM, Ken Sharp ([email protected])
wrote:

At 14:02 15/09/2018 -0700, Paul Wessel wrote:


>We also just noticed a regression w.r.t. transparency today. Â 9.23
>handled transparency correctly, 9.24 broke it, and I just built 9.25 today
>and it still has that problem.

As noted (several times now) on this list, including my reply to the email
you quoted, this is not a regression, it is a deliberate change in
behaviour.

The (non-standard) PostScript extensions for transparency in Ghostscript
were recently used in the series of publicly announced exploits, by abusing
the operands to these operators.

As a result we have chosen to restrict these operators when -dSAFER is true
(because, obviously, these are not safe)

As I also noted, there is an internal review in progress of all the
non-standard PostScript extensions in Ghostscript. You can expect a number
more to disappear, when running in SAFER mode.


>Attached is a 26-line ps file that plots two overlapping squares, the blue
>is transparent. The following gs command produces the PDF which was
>transparent for versions prior to 9.24.
>
>gs -q -dSAFER -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -g2160x2160 -r720
>-sOutputFile=gsbug.pdf -<http://fgsbug.ps>fgsbug.ps

Don't specify -dSAFER.


Ken