[OT] postscript programming q (was: Re: [ILUG] unix mail scri pt virus hole long before windows?)

[Foley, Brian (Galway)]

Hmm...
I don't think you really need to explicitly kill the interpreter. On a real
PS printer, the interpreter is continually running a job server, and when it
falls off the end of a job, that job context is just ended.

Kinda like not needing to explicitly do exit(0); in a C program (albeit for
different reasons).

To duplicate a string you could do something like the following:

%!PS
/s1 (Buffy ) def
/s2 (Summers) def

s1 length s2 length add		% Get the sum of the length of the strings
string					% Create a string that long
dup 0 s1 putinterval			% Put s1 into the string at offset 0
dup s1 length s2 putinterval	% Put s2 into the string at offset
strlen(s1)

==					% Print the (string) object to
stdout

There is a cleaner way that I figured out at some stage. Something to do
with using forall I think. I've got it scribbled down somewhere at home, so
I'll bring it in tomorrow.

Does getenv really exist in GhostScript BTW? Its definitely not in the PS
reference manual, so I assume it must be a GNUism.

Cheers,
Brian.

-----Original Message-----
From: kevin lyda [mailto:kevin at suberic.net]
Sent: 10 July 2001 15:00
To: Foley, Brian (Galway)
Cc: 'Paul Jakma'; ilug at linux.ie
Subject: [OT] postscript programming q (was: Re: [ILUG] unix mail script
virus hole long before windows?)


On Tue, Jul 10, 2001 at 03:57:32PM +0200, Foley, Brian (Galway) wrote:
> %!PS
> /f
> 	(~/i_could_have_deleted_all_your_files) (w) file
> def
> 
> f (You've been PostScripted!) writestring
> f closefile

ok, i forgot to close the file, but you forgot to exit the interpreter!
:)  one thing i was trying to do was to get the home environment var
and use it.  so i wanted to do something like this:

    (HOME) getenv {
	(HOME) getenv \home exch def
	\home + (/i_could_have_deleted_all_your_files) (w) files \out exch
def
    } {
	(/i_could_have_deleted_all_your_files) (w) files \out exch def
    } ifelse

obviously this fails since + doesn't combine strings.  how do you combine
two strings to make one?  something like

    (fu) (bar) concat

kevin