Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!usc!cs.utexas.edu!uunet!zephyr!tektronix!psueea!qiclab!sopwith!snoopy
From: snoopy@sopwith.UUCP (Snoopy)
Newsgroups: gnu.ghostscript.bug
Subject: bugfix for infinite loop in interp (version 1.3)
Keywords: bugfix Ghostscript 1.3 undefined_filename
Message-ID: <229@sopwith.UUCP>
Date: 28 Jun 89 22:15:18 GMT
Reply-To: snoopy@sopwith.UUCP (Snoopy)
Distribution: gnu
Organization: The Daisy Hill Puppy Farm
Lines: 52

Ghostscript 1.3 goes into an infinite loop if you specify a filename
on the command line that does not exist (e.g. you make a typo).

There are a couple of ways (at least) to fix this.  Way number one is to
add e_undefinedfilename to the list of errors that the interpreter doesn't
attempt to retry.  This gets you the "Interp returns -22" message, along
with stack dumps.  Not pretty, but much better than an infinite loop.
(I believe this is what version 1.2 did.)  You could add a printf to the
file_open() function in zfile.c telling what filename couldn't be opened.
(I have mine exit if it is using a hardcopy device.)

Another way, which doesn't require hacking the source and recompiling,
is to modify the definition of the 'run' function in ghost.ps:

change
	  {(r) file}		% let the error happen
to
	  {(\nfile \007) print print ( not found\n\n) print flush} % warn user

Here is the diff for interp.c:

RCS file: RCS/interp.c,v
Retrieving revision 1.2
diff  -c -r1.2 interp.c
*** /tmp/,RCSt1004558	Wed Jun 28 14:53:12 1989
--- interp.c	Wed Jun 28 14:31:51 1989
***************
*** 150,155
  	case e_dictstackoverflow:
  	case e_execstackoverflow:
  	case e_stackoverflow:
  	case e_VMerror:
  		return code;
  	   }

--- 150,156 -----
  	case e_dictstackoverflow:
  	case e_execstackoverflow:
  	case e_stackoverflow:
+ 	case e_undefinedfilename:	/* avoid infinite loop -Snoopy */
  	case e_VMerror:
  		return code;
  	   }


    _____     						  .-----.
   /_____\    Snoopy					./  RIP	 \.
  /_______\   qiclab!sopwith!snoopy			|  	  |
    |___|     parsely!sopwith!snoopy			| tekecs  |
    |___|     sun!nosun!illian!sopwith!snoopy		|_________|

		"I *was* the next man!"  -Indy