Save and Restore

A general architecture for saving and restoring stuff from application data areas to the USB drive.

Security model:

• A binary C-based saverestoremgr service provides the ability to run a set of pre-installed scripts
• The service calls the scripts with a small set of known arguments (e.g. 'save', 'restore', etc)
• The scripts are stored in a location that is only accessible by installing them as root (e.g. a signed app with a post-install script)
• The service does not allow the execution of scripts outside of that location
• Therefore, any script that is run by the service has been installed by a means that already had root access
• The scripts are named according to the appId of the application that owns the data

Features of the service:

• A method to list the current set of available scripts
• A method to call an individual script, or the set of all scripts, with a command method
  • save
  • restore

Implementation Decisions

• Where to store the scripts
  • Needs to be somewhere outside of $IPKG_OFFLINE_ROOT
  • Should be centralised to start, but could be distributed later once things stabilise
  • Choose /var/svc/org.webosinternals.saverestore

Situations To Persist Across

• Partial Erase
• Profile Reset (/var and /media/cryptofs are wiped, but /media/internal is retained)