bug#12123:

[Eli Zaretskii]

> From: chad <yandros@MIT.EDU>
> Date: Fri, 5 Apr 2013 10:27:21 -0700
> 
> Web searching suggests approaches for several specific platforms
> (GNU/Linux, FreeBSD, Solaris, macosx, and Windows) that might be
> useful:
> 
> http://stackoverflow.com/questions/1023306/finding-current-executables-path-without-proc-self-exe

The Windows method mentioned there is exactly what Emacs already uses
on Windows.

Anyway, I see that gnulib has a progreloc module whose purpose is to
make program relocatable.  Perhaps Paul (CC'ed) could import it and
use it in callproc.c to do what Stefan suggested.