The iCalendar reader
phil/calendar-syncICalendar\ICalendarReader::busy() gives the busy periods of an iCalendar text (RFC 5545) that overlap a window. The
adapters ics and caldav read with it; an application may read a calendar it already holds.
What is read
| Component | What gives a period |
|---|---|
VEVENT | Its start, and its end, its duration, or a day for a whole day; a time without either gives none |
VEVENT with RRULE | Each occurrence of the rule that overlaps the window, read by phil/recurrence |
RDATE, EXDATE | Occurrences added and taken away, of the event's length; a period of RDATE by its start |
RECURRENCE-ID | An occurrence changed: read on its own, and taken away from its rule |
VFREEBUSY | Each FREEBUSY period, a start and an end or a duration, but the FREE ones |
An event that is cancelled (STATUS:CANCELLED) or transparent (TRANSP:TRANSPARENT) gives nothing. A tentative event
(STATUS:TENTATIVE) and a BUSY-TENTATIVE period give tentative periods.
Only these properties are read: DTSTART, DTEND, DURATION, RRULE, RDATE, EXDATE, RECURRENCE-ID, UID,
STATUS, TRANSP, FREEBUSY. The others — the title, the description, the place, the guests, the attachments — are
skipped without being decoded, and the properties of a component inside an event, an alarm, are not read.
Time zones
- A time with
Zis in UTC. - A time with
TZIDis in that zone: an IANA name, a leading/dropped, or a Windows name as Outlook writes them, read by ICU. A name neither knows is read in the calendar's zone.VTIMEZONEdefinitions are not read. - A floating time, and a whole day, is in the calendar's zone: the connection's.
The occurrences of a rule keep their first one's time on the wall clock of its zone, across changes of time. The end of an occurrence is as many days and seconds after its start as the event's end is after its own.
Bounds
| Bound | Value |
|---|---|
| The text | 10 MiB |
| Components | 20,000, nested 8 deep |
| A property read | 20,000 bytes once unfolded |
| Repeated events | 1,000, counted before any is expanded, and across the calendar-data of one CalDAV answer |
| Dates added or removed, for an event | 10,000 |
| Periods within the window | 10,000 |
What is refused
A text past a bound is refused with InvalidCalendarData, as is a text that does not start with BEGIN:VCALENDAR,
holds something after its last END:VCALENDAR, ends components out of order or leaves one open, has a line without a
colon or a malformed parameter, an event without a start, a date that is not written 20261110 or 20261110T190000
or that does not exist, a negative or empty duration, or a rule phil/recurrence does not read — an hourly rule, a
BYWEEKNO. A calendar is refused whole rather than half read: half read, it would leave times free that are not.
The reader is a fuzz target: see testing.