[gnome-calendar/fail-in-the-face-of-broken-timezones] event: Don't assume UTC if timezone can't be read

[Ray Strode <halfline src gnome org>]

commit 9f5a84f11d38618248babeb1baf2b74bbe3fc64d
Author: Ray Strode <rstrode redhat com>
Date:   Fri Oct 14 13:57:44 2022 -0400

    event: Don't assume UTC if timezone can't be read
    
    glib currently doesn't read the timezone properly from Toolbx
    containers. This leads GNOME Calendar to sometimes assuming the
    the timezone is UTC.
    
    (See https://gitlab.gnome.org/GNOME/glib/-/merge_requests/2955)
    
    Assuming an arbitrary timezone (even UTC) when the timezone isn't
    available isn't great behavior. It's better to fail, I think.
    
    This commit makes it fail in that case.

 src/core/gcal-event.c | 44 +++++++++++++++++++++++++++++++++-----------
 src/core/gcal-event.h |  4 +++-
 2 files changed, 36 insertions(+), 12 deletions(-)
---
diff --git a/src/core/gcal-event.c b/src/core/gcal-event.c
index 49833a3a..93a9117f 100644
--- a/src/core/gcal-event.c
+++ b/src/core/gcal-event.c
@@ -205,7 +205,7 @@ get_timezone_from_ical (GcalEvent             *self,
    * in this case.
    */
   if (!tz)
-    tz = g_time_zone_new_utc ();
+    return NULL;
 
   GCAL_TRACE_MSG ("%s (%p)", g_time_zone_get_identifier (tz), tz);
 
@@ -314,14 +314,15 @@ setup_component (GcalEvent  *self,
 {
   g_autoptr (GTimeZone) zone_start = NULL;
   g_autoptr (GTimeZone) zone_end = NULL;
-  ECalComponentDateTime *start;
-  ECalComponentDateTime *end;
-  ECalComponentText *text;
+  ECalComponentDateTime *start = NULL;
+  ECalComponentDateTime *end = NULL;
+  ECalComponentText *text = NULL;
   ICalTime *date;
   GDateTime *date_start;
   GDateTime *date_end;
   gboolean start_is_all_day, end_is_all_day;
   gchar *description, *location;
+  gboolean component_setup = FALSE;
 
   g_assert (self->component != NULL);
 
@@ -339,16 +340,24 @@ setup_component (GcalEvent  *self,
                    GCAL_EVENT_ERROR_INVALID_START_DATE,
                    "Event '%s' has an invalid start date", gcal_event_get_uid (self));
 
-      e_cal_component_datetime_free (start);
-      start = e_cal_component_datetime_new_take (i_cal_time_new_today (), NULL);
-      g_clear_pointer (&start, e_cal_component_datetime_free);
-      return FALSE;
+      goto out;
     }
 
   GCAL_TRACE_MSG ("Retrieving start timezone");
 
-  date = i_cal_time_normalize (e_cal_component_datetime_get_value (start));
   zone_start = get_timezone_from_ical (self, start);
+
+  if (!zone_start)
+    {
+      g_set_error (error,
+                   GCAL_EVENT_ERROR,
+                   GCAL_EVENT_ERROR_INVALID_TIME_ZONE,
+                   "Event '%s' has an invalid start date timezone", gcal_event_get_uid (self));
+
+      goto out;
+    }
+
+  date = i_cal_time_normalize (e_cal_component_datetime_get_value (start));
   date_start = g_date_time_new (zone_start,
                                 i_cal_time_get_year (date),
                                 i_cal_time_get_month (date),
@@ -373,8 +382,18 @@ setup_component (GcalEvent  *self,
     {
       GCAL_TRACE_MSG ("Retrieving end timezone");
 
-      date = i_cal_time_normalize (e_cal_component_datetime_get_value (end));
       zone_end = get_timezone_from_ical (self, end);
+
+      if (!zone_end)
+        {
+          g_set_error (error,
+                       GCAL_EVENT_ERROR,
+                       GCAL_EVENT_ERROR_INVALID_TIME_ZONE,
+                       "Event '%s' has an invalid end date timezone", gcal_event_get_uid (self));
+          goto out;
+        }
+
+      date = i_cal_time_normalize (e_cal_component_datetime_get_value (end));
       date_end = g_date_time_new (zone_end,
                                   i_cal_time_get_year (date),
                                   i_cal_time_get_month (date),
@@ -422,14 +441,17 @@ setup_component (GcalEvent  *self,
   g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_HAS_RECURRENCE]);
   g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_RECURRENCE]);
 
+  component_setup = TRUE;
+
   g_clear_pointer (&description, g_free);
   g_clear_pointer (&location, g_free);
 
+out:
   e_cal_component_text_free (text);
   e_cal_component_datetime_free (start);
   e_cal_component_datetime_free (end);
 
-  return TRUE;
+  return component_setup;
 }
 
 
diff --git a/src/core/gcal-event.h b/src/core/gcal-event.h
index a5859db9..82eb08ee 100644
--- a/src/core/gcal-event.h
+++ b/src/core/gcal-event.h
@@ -33,12 +33,14 @@ G_BEGIN_DECLS
 /**
  * GcalEventError:
  * @GCAL_EVENT_ERROR_INVALID_START_DATE: indicated an invalid start date
+ * @GCAL_EVENT_ERROR_INVALID_TIME_ZONE: indicated an invalid time zone
  *
  * Errors that #GcalEvent can generate.
  */
 typedef enum
 {
-  GCAL_EVENT_ERROR_INVALID_START_DATE
+  GCAL_EVENT_ERROR_INVALID_START_DATE,
+  GCAL_EVENT_ERROR_INVALID_TIME_ZONE,
 } GcalEventError;
 
 #define GCAL_EVENT_ERROR gcal_event_error_quark ()