RFC: reducing wasted disk space from addon files

[Erich E. Hoover]

On Wed, Mar 6, 2019 at 6:05 AM Jacek Caban <jacek at codeweavers.com> wrote:
>
> On 3/5/19 4:41 PM, Vincent Povirk wrote:
> > ...
> > I'm starting to favor the CAB approach for this reason.
> We used CAB files in very early Wine Gecko days, the move to MSI was a
> nice change. It moved installation logic to the right place. In case of
> Gecko it's not really a big deal: one directory and one registry key, so
> I don't feel strongly about it.

MSI files contain a CAB file within them, so if all you need is the
ability to distribute a single unified file then we can just
distribute an MSI file and extract the CAB.  I have patches in staging
for implementing msidb (the tool needed to do this), so you could
conceivably build a process around:
1) download MSI
2) extract CAB with msidb
3) unpack CAB with cabextract to the desired destination folder
This may not be the best approach though, depending on what you want
to achieve (read on).

> ...
> If we stayed with MSI instead of CAB (probably we'd need both .msi for
> downloader and .tar.* file for shared install) then, we'd have two Mono
> MSIs. Let's call them big and small. I have limited knowledge about MSI,
> but it should be possible to have small MSI be both part of the big
> package and its dependency. With that, current appwiz.cpl should work
> out of the box - small MSI would be installed as part of big MSI.

Yes, it is possible to have one MSI installer call another installer.
It is also possible to have an MSI installer dependent upon
environment variables (so the environment variable tells it not to
unpack the files, so it just installs the registry keys).  It is also
possible to create MSI installers that use _separate_ CAB files (not
included in the MSI file itself), so you can download the MSI
instructions but not download the "files".  If you combine this with
environment-variable control then you can conceivably save download
bandwidth and use a single MSI for both "shared" and "prefix-specific"
behavior.  This technique also has the benefit of giving you the CAB
file you want without having to extract it from the MSI file.

I, regrettably, have a lot of experience creating strange installers
like this.  If you are interested in this approach then I can put
together a simple example to demo how this approach can work.

Best,
Erich