[help-gv] gv patch

[Andrew . Hamilton]

Markus,

> thanks for sending us your patch. I am testing it. If it works as 
> expected, I'll include it in the next release of GNU gv.

Thanks.  Warning: you will find that a PostScript file <file.ps>
containing Document Structuring Conventions (DSC) will NOT work in
cat <file.ps> | gv -
Currently only vanilla PostScript files work (e.g. a single PostScript graphic).

The reason for the failure is a bug in gs, the fix for which is
documented in the patch file:
+    if (gvw->ghostview.filename && !strcmp(gvw->ghostview.filename,"-")) {
+       /* The ghostscript documentation states that the "-" argument
+         tells gs that input is coming from a pipe rather than from stdin.
+         One of the side effects of the "-" argument is that gs does not
+         flush output at each line of input, but rather accumulates input
+         and flushes only when the buffer is full.  Since we want gs to
+         flush output at each line of input, we therefore cannot send "-".
+         Unfortunately not sending "-" has the side effect that gs no
+         longer reads correctly through either multiple PostScript files
+         or PostScript files with multiple pages.  Ah well.
+         Should gs ever acquire a -DFLUSH argument, then send gs that argument,
+         and uncomment the following line.  */
+       /* argv[argc++] = "-"; */

So please don't reject the patch just because it fails in this case.
The problem is not with gv or the patch, but rather with gs.

Thanks, Andrew