Re: [AUCTeX] showing xdvi messages

[Ralf Angeli]

* Werner LEMBERG (2005-12-28) writes:

>> Maybe xdvi aborts
>> because it cannot write to stdout?
>
> I have no idea :-)  What do you think about contacting the emacs-devel
> list?  They can probably help...

I guess I should read something about `fork' before asking there and
wasting people's time.  Meanwhile I found the following code snippet
while grepping through xdvik's sources in xdvi-search.el:

    (if (xdvi-has-nofork (car xdvi-version-info) (car (cdr xdvi-version-info)))
        (progn
          (setq proc
                (start-process "xdvi" "*xdvi output*"
                               xdvi-bin
                               "-nofork"
                               "-sourceposition"
                               (concat (int-to-string curr-line) " " filename)
                               dvi-file))
          (set-process-sentinel proc 'xdvi-process-sentinel))
      ;;;
      ;;; More complicated if we don't have nofork: start a
      ;;; subshell, since otherwise there's no way of viewing
      ;;; the stderr/stdout output of the xdvi child process
      ;;; without having either xdvi freezing, Emacs freezing,
      ;;; or Emacs killing the xdvi child process (which is
      ;;; forked when running with -sourceposition).
      ;;;
      ;;; Obtain the type of I/O-redirection needed for current shell:
      (let* ((default-shell
               (or (and (boundp 'explicit-shell-file-name) 
explicit-shell-file-name)
                   (getenv "ESHELL")
                   (getenv "SHELL")
[...]

That means we could work around the problem by calling xdvi with
-nofork.  I just have to check for how long this option has been
supported in xdvik and if the non-k xdvi supports it, too.  Then we
can decide if we simply have to add -nofork to the xdvi call and are
done.

I don't know how common it is that applications which fork and write
stuff to stdout are called from within Emacs.  But if this happens on
a frequent basis it would be interesting to know if Emacs could
support this.  That could be asked on emacs-devel, but if possible
with an easier testcase than calling xdvi with -sourceposition.

-- 
Ralf