Re: guile-2.0 on mingw: the sequel

[Mark H Weaver <mhw@netris.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Mark H Weaver <mhw@netris.org>
>> Cc: Eli Zaretskii <eliz@gnu.org>,  "guile-user\@gnu.org" <guile-user@gnu.org>
>> Date: Fri, 23 Aug 2013 11:13:19 -0400
>> 
>> Of course, ideally we would allow the entire Guile install to be freely
>> relocatable, as Windows users have come to expect.  This would require
>> some help from a Windows developer.
>
> Why should this feature be limited to Windows builds of Guile?  Why
> not make it work for Posix platforms as well?  Some other projects
> already do, they use argv[0] and PATH search to find the place where
> the executable is installed, and record relative file names from
> there.

Well, that's not generally how things are done on POSIX systems, and
furthermore I don't see how this could be made to work reliably on
POSIX.  The location of the Guile executable is sometimes not found in
either argv[0] or PATH.  For example, if you run the following script:

--8<---------------cut here---------------start------------->8---
#!/usr/local/bin/guile -s
!#

(format #t "~s~%" (program-arguments))
--8<---------------cut here---------------end--------------->8---

argv[0] will point to the script, not the Guile executable.  I suppose
we could detect if argv[0] points to a script and read the shebang (and
iterate, if the shebang points to another script), but even that doesn't
cover all cases.  It's possible to pass any arbitrary value for argv[0]
using the 'exec' family of system calls.

    Regards,
      Mark