e-cal-check-timezones
3
LIBECAL Library

# e-cal-check-timezones

## Synopsis

    gboolean            e_cal_check_timezones               (icalcomponent *comp,
                                                             GList *comps,
                                                             icaltimezone* (tzlookupconst char *tzid,const void *custom,GError **error) (),
                                                             const void *custom,
                                                             GError **error);
    icaltimezone *      e_cal_tzlookup_ecal                 (const char *tzid,
                                                             const void *custom,
                                                             GError **error);
    icaltimezone *      e_cal_tzlookup_icomp                (const char *tzid,
                                                             const void *custom,
                                                             GError **error);
    const char *        e_cal_match_tzid                    (const char *tzid);

## Description

## Details

### e_cal_check_timezones ()

    gboolean            e_cal_check_timezones               (icalcomponent *comp,
                                                             GList *comps,
                                                             icaltimezone* (tzlookupconst char *tzid,const void *custom,GError **error) (),
                                                             const void *custom,
                                                             GError **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, e_cal_get_component_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 is 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.

`comp` :

  a VCALENDAR containing a list of VTIMEZONE and arbitrary other components, in arbitrary order: these other components are modified by this call

`comps` :

  a list of icalcomponent 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_check_timezones()` (to be compatible with `e_cal_get_timezone()`); NULL indicates that no such timezone exists or an error occurred

`custom` :

  an arbitrary pointer which is passed through to the tzlookup function

`error` :

  an error description in case of a failure

Returns :

  TRUE if successful, FALSE otherwise.

### e_cal_tzlookup_ecal ()

    icaltimezone *      e_cal_tzlookup_ecal                 (const char *tzid,
                                                             const void *custom,
                                                             GError **error);

An implementation of the tzlookup callback which clients can use. Calls e_cal_get_timezone.

`tzid` :

`custom` :

  must be a valid ECal pointer

`error` :

Returns :

### e_cal_tzlookup_icomp ()

    icaltimezone *      e_cal_tzlookup_icomp                (const char *tzid,
                                                             const void *custom,
                                                             GError **error);

An implementation of the tzlookup callback which backends like the file backend can use. Searches for the timezone in the component list.

`tzid` :

`custom` :

  must be a icalcomponent pointer which contains either a VCALENDAR with VTIMEZONEs or VTIMEZONES directly

`error` :

Returns :

### e_cal_match_tzid ()

    const char *        e_cal_match_tzid                    (const char *tzid);

`tzid` :

Returns :