[GRASS5] White spaces support

[Markus Neteler]

On Thu, Feb 27, 2003 at 08:39:15PM +0000, Glynn Clements wrote:
> 
> Markus Neteler wrote:
> 
> > I have commited some changes to CVS to support white space
> > to some extend.
> > 
> > GRASS:/tmp/grass data > g.gisenv
> > GISDBASE=/tmp/grass data
> > LOCATION_NAME=rmapcalcUTM
> > MAPSET=PERMANENT
> > MONITOR=x0
> > GRASS_GUI=text
> > 
> > GRASS:/tmp/grass data > pwd
> > /tmp/grass data
> > GRASS:/tmp/grass data > l
> > total 4
> > drwxr-xr-x    3 neteler  ssi          4096 Feb 27 16:12 rmapcalcUTM
> > GRASS:/tmp/grass data >
> > 
> > It's possible to start GRASS now with white spaces.
> 
> But is it possible to use it? If it isn't, it might be better if GRASS
> simply refused to start.

I tried some modules which worked well (except g.list).
Only if we try that we can find out what's missing.

> Also, in most of the cases where users have had problems due to
> whitespace, the problem has been due to their home directory rather
> than GISDBASE. This is arguably a more serious problem, as the user
> can choose where to put GISDBASE, but they don't necessarily get to
> choose their home directory.

Right. Perhaps someone with Cygwin installed could try it again
and report where it fails (if).
 
> > Hope that it doesn't break anything,
> > but the changes are just variable quoting in the start shell 
> > scripts.
> 
> I suspect that many shell[1] scripts will be broken for similar
> reasons. Similarly for anything which passes to system() or popen()
> any filenames which are within GISDBASE.
> 
> For system() etc, use single quotes, e.g. change:
> 
> 	sprintf(buff, "command %s", filename); system(buff);
> to:
> 	sprintf(buff, "command '%s'", filename); system(buff);

Ok.

> This should handle any filename except one which contains a single
> quote character (which is pretty unlikely). Ultimately, use of
> system() should be eliminated.

Yes. We could issue that for 5.1, while migrating code into the 5.1
repository.
There are maybe 5 system calls in 5.1 currently.
Recommendations are welcome.
 
> [1] Tcl/Tk mostly[2] avoids the problem, as it performs tokenisation
> (splitting the string into words) before it expands variables; when a
> variable is expanded to its value, the result remains a single token
> even if it contains whitespace.
> 
> [2] However, using a variable within a double-quoted string which is
> subsequently tokenised (e.g. eval "...", open "|...") will have the
> same problem.
> 
> -- 
> Glynn Clements <glynn.clements at virgin.net>

This was just a first step (a favor for the MS-Win world).

Markus