sousa-gecko/tools/update-verify/marannon

Overview

Marannon is a tool for verifying the integrity of MAR files.

How it Works

In order to be considered valid, a MAR file must bring a user on an existing version of an application to the an equivalent state that the installer for the same version is in. This helps ensure that the new install will function, and that future updates will succeed.

This is accomplished by:

1. Unpacking an installer from an older application version (the from build) and a newer application version (the to build).
2. Running the updater from the from build to apply a MAR file on top of it.
3. Diffing the state of from build (which should now be the same version as the to build) against the unpacked to build.
4. Analyzing the diff for any noteworthy differences.

The details of how builds are unpacked, how the updater is run, and how differences are analyzed differ between platforms, but the basic operation is the same.

Allowable Differences

A MAR file need not (and typically does not) update every single file on an install, and thus will contain some expected differences. In typical use cases we expect that files related to the configuration of the updater (channel-prefs.js and update-settings.ini) may differ between the updated from build and the unpacked to build.

Etymology

Like some other update-related tools and systems, its name derives from J.R.R. Tolkein's legendarium and is a combination of MAR (Mozilla ARchive) and the Sindarin word annon, meaning gate or door. Roughly translated, it means "MAR gateway", ie: something through which MAR files must pass before shipping.