Patchwork D9891: wix: tell ComponentSearch that it is finding a directory (not a file)

spectral created this revision.
Herald added a reviewer: hg-reviewers.
Herald added a subscriber: mercurial-patches.

REVISION SUMMARY
  This is to fix an issue we've noticed where fresh installations start at
  `C:\Program Files\Mercurial`, and then upgrades "walk up" the tree and end up in
  `C:\Program Files` and finally `C:\` (where they stay).
  
  ComponentSearch defaults to finding files, which I think means "it produces a
  string like `C:\Program Files\Mercurial`", whereas with the type being
  explicitly a directory, it would return `C:\Program Files\Mercurial\` (note the
  final trailing backslash). Presumably, a latter step then tries to turn that
  file name into a proper directory, by removing everything after the last `\`.
  
  This could likely also be fixed by actually searching for the component for
  hg.exe itself. That seemed a lot more complicated, as the GUID for hg.exe isn't
  known in this file (it's one of the "auto-derived" ones). We could also consider
  adding a Condition that I think could check the Property and ensure it's either
  empty or ends in a trailing slash, but that would be an installer runtime check
  and I'm not convinced it'd actually be useful.
  
  This will *not* cause existing installations that are in one of the bad
  directories to fix themselves. Doing that would require a fair amount more
  understanding of wix and windows installer than I have, and it *probably*
  wouldn't be possible to be 100% correct about it either (there's nothing
  preventing a user from intentionally installing it in C:\, though I don't know
  why they would do so).
  
  If someone wants to tackle fixing existing installations, I think that the first
  installation is actually the only one that shows up in "Add or Remove Programs",
  and that its registry keys still exist. You might be able to find something
  under HKEY_USERS that lists both the "good" and the "bad" InstallDirs. Mine was
  under `HKEY_USERS\S-1-5-18\Software\Mercurial\InstallDir` (C:\), and
  `HKEY_USERS\S-1-5-21-..numbers..\Software\Mercurial\InstallDir` (C:\Program
  Files\Mercurial). If you find exactly two, with one being the default path, and
  the other being a prefix of it, the user almost certainly hit this bug :D
  
  We had originally thought that this bug might be due to unattended
  installations/upgrades, but I no longer think that's the case. We were able to
  reproduce the issue by uninstalling all copies of Mercurial I could find,
  installing one version (it chose the correct location), and then starting the
  installer for a different version (higher or lower didn't matter). I did not
  need to deal with an unattended or headless installation/upgrade to trigger the
  issue, but it's possible that my system was "primed" for this bug to happen
  because of a previous unattended installation/upgrade.

REPOSITORY
  rHG Mercurial

BRANCH
  default

REVISION DETAIL
  https://phab.mercurial-scm.org/D9891

AFFECTED FILES
  contrib/packaging/wix/mercurial.wxs

CHANGE DETAILS




To: spectral, #hg-reviewers
Cc: mercurial-patches, mercurial-devel