check_timezones_sync

Description:

[ Version ( since = "3.34" ) ]
public static bool check_timezones_sync (Component vcalendar, SList<Component>? icalcomps, RecurResolveTimezoneCb? tzlookup, Cancellable? cancellable = null) throws Error

This function cleans up VEVENT, VJOURNAL, VTODO and VTIMEZONE items which are to be imported into Evolution.

Using VTIMEZONE definitions is problematic because they cannot be updated properly when timezone definitions change. They are also incomplete ( for compatibility reason only one set of rules for summer saving changes can be included, even if different rules apply in different years). This function looks for matches of the used TZIDs against system timezones and replaces such TZIDs with the corresponding system timezone. This works for TZIDs containing a location (found via a fuzzy string search) and for Outlook TZIDs (via a hard-coded lookup table).

Some programs generate broken meeting invitations with TZID, but without including the corresponding VTIMEZONE. Importing such invitations unchanged causes problems later on (meeting displayed incorrectly, get_as_string fails). The situation where this occurred in the past (found by a SyncEvolution user) is now handled via the location based mapping.

If this mapping fails, this function also deals with VTIMEZONE conflicts: such conflicts occur when the calendar already contains an old VTIMEZONE definition with the same TZID, but different summer saving rules. Replacing the VTIMEZONE potentially breaks displaying of old events, whereas not replacing it breaks the new events (the behavior in Evolution <= 2.22.1).

The way this problem is resolved by renaming the new VTIMEZONE definition until the TZID is unique. A running count is appended to the TZID. All items referencing the renamed TZID are adapted accordingly.

Parameters:

vcalendar	a VCALENDAR containing a list of VTIMEZONE and arbitrary other components, in arbitrary order: these other components are modified by this call
icalcomps	a list of Component instances which also have to be patched; may be null
tzlookup	a callback function which is called to retrieve a calendar's VTIMEZONE definition; the returned definition is not freed by `e_cal_client_check_timezones` NULL indicates that no such timezone exists or an error occurred
cancellable	a Cancellable to use in `tzlookup` function
tzlookup_data	an arbitrary pointer which is passed through to the `tzlookup` function

Returns:

true if successful, false otherwise.