theme_update_report in core/modules/update/
Returns HTML for the project status report.
update_calculate_project_update_status in core/modules/update/
Calculates the current update status of a specific project.
update_get_available in core/modules/update/update.module
Tries to get update information from cache and refreshes it when necessary.
_update_get_cached_available_releases in core/modules/update/update.module
Returns all currently cached data about available releases for all projects.
_update_message_text in core/modules/update/update.module
Returns the appropriate message text when site is out of date or not secure.
_update_requirement_check in core/modules/update/update.install
Fills in the requirements array.