Correct the start time of planned dives

Subsurface follows the lead of most divecomputers to use times without
timezone - so all times are implicitly assumed to be local time of the
dive location; so in order to give the current time in that way we
actually need to add the timezone offset.

Instead of relying on OS specific members of struct tm we use the glib
timezone functions to get the timezone offset for us. Of course, the
function used to do this is only in glib 2.26 or newer, which once again
means that Debian stable won't be supported. But since that doesn't build
other parts of Subsurface, either, I think I'll live with that.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 14 insertions, 2 deletions

diff --git a/planner.c b/planner.c
index 4389aac50..bf6bd5439 100644
--- a/planner.c
+++ b/planner.c
@@ -806,6 +806,17 @@ static gboolean duration_focus_out_cb(GtkWidget *entry, GdkEvent * event, gpoint
 	return FALSE;
 }
 
+/* Subsurface follows the lead of most divecomputers to use times
+ * without timezone - so all times are implicitly assumed to be
+ * local time of the dive location; so in order to give the current
+ * time in that way we actually need to add the timezone offset */
+static timestamp_t current_time_notz(void)
+{
+	timestamp_t now = time(NULL);
+	int offset = g_time_zone_get_offset(g_time_zone_new_local(), 1);
+	return now + offset;
+}
+
 static gboolean starttime_focus_out_cb(GtkWidget *entry, GdkEvent * event, gpointer data)
 {
 	const char *starttimetext;
@@ -814,7 +825,7 @@ static gboolean starttime_focus_out_cb(GtkWidget *entry, GdkEvent * event, gpoin
 	starttimetext = gtk_entry_get_text(GTK_ENTRY(entry));
 	if (validate_time(starttimetext, &starttime, &is_rel)) {
 		/* we alway make this relative for now */
-		diveplan.when = time(NULL) + starttime;
+		diveplan.when = current_time_notz() + starttime;
 		show_planned_dive();
 	} else {
 		/* we need to instead change the color of the input field or something */
@@ -905,6 +916,7 @@ static void add_waypoint_cb(GtkButton *button, gpointer _data)
 	}
 }
 
+/* set up the dialog where the user can input their dive plan */
 void input_plan()
 {
 	GtkWidget *planner, *content, *vbox, *hbox, *outervbox, *add_row, *deltat, *label, *surfpres;
@@ -949,7 +961,7 @@ void input_plan()
 	gtk_entry_set_text(GTK_ENTRY(surfpres), pressurebuf);
 	gtk_widget_add_events(surfpres, GDK_FOCUS_CHANGE_MASK);
 	g_signal_connect(surfpres, "focus-out-event", G_CALLBACK(surfpres_focus_out_cb), NULL);
-	diveplan.when = time(NULL) + 3600;
+	diveplan.when = current_time_notz() + 3600;
 	diveplan.surface_pressure = SURFACE_PRESSURE;
 	nr_waypoints = 4;
 	add_waypoint_widgets(vbox, 0);