[gs-cvs] rev 8159 - trunk/gs/lib

[ray at ghostscript.com]

Author: ray
Date: 2007-08-01 10:19:50 -0700 (Wed, 01 Aug 2007)
New Revision: 8159

Modified:
   trunk/gs/lib/pdf_main.ps
Log:
Fix for gv hang, where an application sends (less than 1023 bytes)
PostScript and expects a response. AppleTalk PAP and some other
interactive viewer front ends may run into this. Bug #689237.

DETAILS:

The autosense is still sort of fragile in that we only process
PostScript immediately without waiting for the .peekstring of
1023 bytes to complete if it begins with "%!" or "%%". The
check for "%%" is needed for gv, conventionally "%!" is more
widely used. Note this really only affects applications using
gs as a process getting data from stdin and expecting immediate
action (response or other processing).

Also note that the %! or %% is only looked for as the first
two characters so that the presence of this in garbage before
an actual PDF won't cause confusion.

EXPECTED DIFFERENCES:

None.

Note I also tested with the files mentioned in Bug #687125
which are not part of our comparefiles suite just to make
sure that this still worked as expected.


Modified: trunk/gs/lib/pdf_main.ps
===================================================================
--- trunk/gs/lib/pdf_main.ps	2007-08-01 04:10:13 UTC (rev 8158)
+++ trunk/gs/lib/pdf_main.ps	2007-08-01 17:19:50 UTC (rev 8159)
@@ -79,48 +79,55 @@
   } loop
   exch pop
   {
-    dup 1023 string .peekstring pop dup length 400 ge {
-      % "1024 string" exceeds current %stdin buffer
-      % Valid PDF file cannot be smaller than 400 bytes.
-      (%PDF-1.) search {
-        3 1 roll pop pop
-        dup (%!PS) search not {
-          length 0 ne { 
-            1 index exch readstring pop pop
-            (%stderr) (w) file dup 
-            (   **** Warning: File has some garbage before %PDF-1. .\n)
-            writestring flushfile
-          } { 
-            pop
-          } ifelse
-          dup (%stdin) (r) file eq {
-            % Copy PDF from stdin to temporary file then run it.
-            null (w+) //systemdict /.tempfile get exec exch 3 1 roll
-            % stack: tempname stdin tempfile
-            64000 string
-            {
-              % stack: tempname stdin tempfile string
-              2 index 1 index readstring
-              exch 3 index exch writestring
-              not { exit } if
-            }
-            loop
-            pop exch closefile
-            % stack: tempname tempfile
-            dup 0 setfileposition
-            dup runpdf
-            closefile deletefile
-          } { 
-            runpdf
-          } ifelse
-        } {
-          pop pop pop pop cvx .runps % (%!PS) found first
-        } ifelse
+    % Appletalk PAP sends short strings with %! header expecting a response. 
+    % 'gv' swallows the %!PS line, then sends DSC comments beginning with %%
+    % and also waits for a response. The following avoids those hangs.
+    dup 2 string .peekstring pop dup (%!) eq exch (%%) eq or {
+      cvx .runps
+    } {
+      dup 1023 string .peekstring pop dup length 400 ge {
+	% "1024 string" exceeds current %stdin buffer
+	% Valid PDF file cannot be smaller than 400 bytes.
+	(%PDF-1.) search {
+	  3 1 roll pop pop
+	  dup (%!PS) search not {
+	    length 0 ne { 
+	      1 index exch readstring pop pop
+	      (%stderr) (w) file dup 
+	      (   **** Warning: File has some garbage before %PDF-1. .\n)
+	      writestring flushfile
+	    } { 
+	      pop
+	    } ifelse
+	    dup (%stdin) (r) file eq {
+	      % Copy PDF from stdin to temporary file then run it.
+	      null (w+) //systemdict /.tempfile get exec exch 3 1 roll
+	      % stack: tempname stdin tempfile
+	      64000 string
+	      {
+		% stack: tempname stdin tempfile string
+		2 index 1 index readstring
+		exch 3 index exch writestring
+		not { exit } if
+	      }
+	      loop
+	      pop exch closefile
+	      % stack: tempname tempfile
+	      dup 0 setfileposition
+	      dup runpdf
+	      closefile deletefile
+	    } { 
+	      runpdf
+	    } ifelse
+	  } {
+	    pop pop pop pop cvx .runps % (%!PS) found first
+	  } ifelse
+	} { 
+	  pop cvx .runps % (%PDF-1.) not found
+	} ifelse
       } { 
-        pop cvx .runps % (%PDF-1.) not found
+	pop cvx .runps   % too short for PDF
       } ifelse
-    } { 
-      pop cvx .runps   % too short for PDF
     } ifelse
   } {
     closefile % file was empty