1497271 - Add diagnostic logging to the PostUpdate function

Status: NEW

(Firefox :: Installer, enhancement, P3)

Description

[Molly Howell (she/her) (mostly inactive)]

The PostUpdate function is a chunk of NSIS code that runs during an update after we're finished actually patching the application files. Its role is broadly to update the things that the installer created; registry entries, shortcuts, any necessary DLL registrations, and so forth.

Currently the only way we have to diagnose problems that occur in this function is to observe the aftermath and try to work backwards to see what decisions it came to. This makes it very difficult to diagnose things like bug 1496267, where we can see what the problem is but nothing really tells us how it happened.

If PostUpdate wrote a log file, we could use it to record each decision and action and we wouldn't have to guess. This should mean that troubleshooting this type of bugs gives us a much less annoying time.