Add a birthDate field to the JSON user record, stored internally as a
struct tm with INT_MIN/negative sentinels for unset fields. The field
is serialized as a YYYY-MM-DD string in JSON and validated via
parse_birth_date(), which shares its core logic with
parse_calendar_date() through a new parse_calendar_date_full()
function.
For birth dates, timegm() is called directly (rather than
mktime_or_timegm_usec) to support pre-epoch dates. The wday field is
used to distinguish timegm() failure from a valid (time_t) -1 return.
birthDate is excluded from user_record_self_modifiable_fields(), so
only administrators can set or change it via homectl. The field
remains in the regular (non-privileged) JSON section, keeping it
readable by the user and applications.
Move the YYYY-MM-DD date parsing and validation logic from
sysupdate-resource.c into a shared parse_calendar_date() function
in time-util, so it can be reused by other subsystems.
Mark realName, emailAddress, and location as sensitive in JSON user
records so that they are excluded from debug log output. These fields
contain personally identifiable information that should not be leaked
in logs, which are generally more accessible than the user database
itself.
Dylan M. Taylor