[PATCH] hooks: allow Unix style environment variables on external Windows hooks

[Yuya Nishihara]

On Tue, 04 Jul 2017 12:42:08 +0900, FUJIWARA Katsunori wrote:
> At Mon, 03 Jul 2017 21:57:01 -0400,
> Matt Harbison wrote:
> > On Mon, 03 Jul 2017 12:15:49 -0400, FUJIWARA Katsunori  
> > <foozy at lares.dti.ne.jp> wrote:
> > >> >  def _exthook(ui, repo, htype, name, cmd, args, throw):
> > >> > +    if pycompat.osname == 'nt':
> > >> > +        # Replace Unix style environment variables with Windows  
> > >> style variables,
> > >> > +        # for replacement by cmd.exe.  Treat '\$' as a literal $.
> > >> > +        def replacer(m):
> > >> > +            prefix = m.group(1)
> > >> > +            if prefix == '\\':
> > >> > +                return '$' + m.group(2)
> > >> > +            return prefix + '%' + m.group(2) + '%'
> > >> > +
> > >> > +        cmd = re.sub(br'(.?)\$(.+?)\b', replacer, cmd)
> > >
> > > How about '(.?)\$([A-Za-z_]\w*)' for more strict matching against
> > > variable name?
> > 
> > Unfortunately, that strictness is... optimistic:
> > 
> > https://ss64.com/nt/syntax-variables.html
> > 
> > Names can include spaces, '{', '}', and '$'.  Ugh.
> > 
> > Or are you saying we don't need to support those characters, because they  
> > wouldn't be portable anyway?  (The fact that there are built-ins with some  
> > non portable characters like 'COMMONPROGRAMFILES(X86)' gives me slight  
> > pause, though I've never seen any of the other characters in practice.   
> > And mostly the convenience is when using variables exported by hg.)
> 
> Yes, I think that platform specific characters and features
> (substitutions, and so on) can be omitted, because main concern of
> this patch is portability of external hook command line between
> platforms.

FWIW, I found ntpath.expandvars() does support $name and ${name} on Windows.

https://docs.python.org/2/library/os.path.html#os.path.expandvars