Re: [bug-gv] gv fails when fed via pipe

[Nuno Silva]

On Mon, May 05, 2014 at 10:09:18AM +0300, Nuno Silva wrote:
> On Sun, May 04, 2014 at 12:28:42PM -1000, Paul Wessel wrote:
> > Hi list-
> > 
> > I have noticed that gv often crashes when a process writes PostScript
> > directly to it via a pipe while the same PostScript, if first saved to
> > a file, opens fine.  These cases always involves the image operator.
> > We _think_ we are writing the PS correctly as it works in all other
> > contexts except the piping via gv.
> > 
> > Attached is a small example (issue.ps) that demonstrates the
> > issue. For instance,
> > 
> > gv issue.ps [works fine]
> > gv - < issue.ps [gives errors]
> > 
> > I am using gv version 3.7.4 installed via macports on OSX 10.9.2.
> 
> I can reproduce this with gv 3.7.3 on Gentoo GNU/Linux. I also did some
> quick tests with other tools that (AFAIK) use ghostscript internally,
> and they did *not* have this issue: convert (imagemagick), ps2pdf.
> 
> 
>   $ convert - issue.png < issue.ps
> 
>   $ ps2pdf - issue.pdf < issue.ps
> 
> I did also try with ghostscript as well, and it worked:
> 
>   $ gs -q -sPAPERSIZE=a4 -dBATCH -dNOPAUSE -sDEVICE=ps2write \
>      -sOutputFile=out.ps - < issue.ps
> 
> 
> Converting PDF files with images to postscript, and then invoking gv in
> the same way on the resulting postscript files seems to trigger some
> error as well.


Looking at the code of the release of gv I am using, I see the comment
in line 1443[0] of src/Ghostview.c, explaining why gv does not pass "-" to
ghostscript.


[0] after 
'if (gvw->ghostview.filename && !strcmp(gvw->ghostview.filename,"-")) {'


In fact, if I call gs without "-", the image does *not* get
converted. If I omit -dBATCH, I will get a ghostscript error as well.

  $ gs -sPAPERSIZE=a4 -dNOPAUSE -sDEVICE=ps2write -sOutputFile=out.ps \
    < issue.ps

I don't know enough about ghostview or ghostscript, so I have no idea if
this can be fixed or not.

-- 
Nuno Silva (aka njsg)