setup.exe problem with selecting "curr" radio button

[Max Bowsher]

Brian Dessent wrote:
> Just today I noticed a buglet in setup.exe where it will "lose" some
> dependencies when pressing the "curr" radio button, even if that is the
> current selected choice.  That kind of violates the principle that
> selecting something that's already selected shouldn't have any effect.
>
> Here's a very simple example that illustrates how bad it can be.  Move
> your current cygwin setup away to a safe place (mount -m > mounts.bat;
> umount -A; ren \cygwin \cygwin-old) and run setup.  Change absolutely
> nothing, i.e. take all the defaults.  You should get the standard base
> system which currently consists of:
>
> ash base-files base-passwd bash bzip2 coreutils cygutils cygwin
> cygwin-doc diffutils editrights findutils gawk gdbm grep groff gzip less
> libbz2_1 libcharset1 libgdbm libgdbm-devel libgdbm3 libgdbm4 libiconv
> libiconv2 libintl libintl1 libintl2 libintl3 libncurses5 libncurses6
> libncurses7 libncurses8 libpcre libpcre0 libpopt0 libreadline4
> libreadline5 libreadline6 login man mktemp ncurses readline sed tar
> termcap terminfo texinfo which zlib _update-info-dir
>
> Okay, fair enough.  Now blow away that installation and try again.  This
> time do the same thing, accept all the defaults, BUT click on "curr"
> even though that radio button is already selected, and press Next.
> Setup helpfully removes a bunch of critical packages.  You get the above
> list of packages MINUS (!!) the following:
>
> groff less libz2_1 libcharset1 libiconv libintl libintl1 libintl3
> libpcre libpcre0, libpopt0 mktemp
>
> Needless to say you get a real headache when it comes to try to run the
> postinstall scripts, particularly the missing cygintl-3.dll and
> cygpopt-0.dll.  In this example you get about three dozen popup "missing
> DLL" errors.  If you run setup a second time and accept setup's choices
> you will see the above list of packages in the "partial" view as setup
> finds and selects all the missing stuff.
>
> It seems that what's happening is that when you press "curr" setup tries
> to reselect the current version of every package, but in doing so it
> misses some things, and since they were not installed before (since
> *nothing* was installed before) they get deselected.  I haven't looked
> at the setup code all that thoroughly but if I recall correctly there's
> a hard-coded limit of 5 levels of recursion in there to prevent
> looping.  Perhaps the dependency tree for a system with no current
> packages installed is deep enough that setup is hitting that and
> stopping early.  I don't really know.  But it would explain a lot of the
> support emails that basically amount to "I have this error saying
> missing cygfoo.dll!" where cygfoo.dll is some dependent lib that setup
> should have installed but didn't.  I always thought it was people
> deselecting things they thought they didn't need, but setup might be
> causing it if they clicked back and forth between curr/test a couple of
> times or something.

Wow!

Very useful info!

It may take me a while to comprehend the dependency code, but bugzilla-ed 
for now.

Max.