core: create fake cylinder at end of cylinder table (hack!)

When we had fixed-sized cylinder arrays, the planner used the last
empty cylinder for "surface air". This was not recognized by the UI
as a separate cylinder, because "empty cylinder" was the sentinel for
the end of the table. The conversion to dynamically sized cylinder
tables broke this code: everytime the surface segment is changed,
a new dummy cylinder is added, which is visible in the UI.

As a very temporary stop-gap fix, emulate the old code by creating
a cylinder and then setting the end-of-table to before that cylinder.
This means that we have to loosen the out-of-bound checks.

That's all very scary and should be removed as soon as possible.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

3 files changed, 19 insertions, 9 deletions

diff --git a/core/dive.c b/core/dive.c
index 89e090165..b4fa22d24 100644
--- a/core/dive.c
+++ b/core/dive.c
@@ -227,7 +227,10 @@ struct event *add_event(struct divecomputer *dc, unsigned int time, int type, in
 void add_gas_switch_event(struct dive *dive, struct divecomputer *dc, int seconds, int idx)
 {
 	/* sanity check so we don't crash */
-	if (idx < 0 || idx >= dive->cylinders.nr) {
+	/* FIXME: The planner uses a dummy cylinder one past the official number of cylinders
+	 * in the table to mark no-cylinder surface interavals. This is horrendous. Fix ASAP. */
+	//if (idx < 0 || idx >= dive->cylinders.nr) {
+	if (idx < 0 || idx >= dive->cylinders.nr + 1 || idx >= dive->cylinders.allocated) {
 		report_error("Unknown cylinder index: %d", idx);
 		return;
 	}
diff --git a/core/equipment.c b/core/equipment.c
index 8d169d8d2..a5acb776d 100644
--- a/core/equipment.c
+++ b/core/equipment.c
@@ -368,7 +368,10 @@ cylinder_t *add_empty_cylinder(struct cylinder_table *t)
  */
 cylinder_t *get_cylinder(const struct dive *d, int idx)
 {
-	if (idx < 0 || idx >= d->cylinders.nr) {
+	/* FIXME: The planner uses a dummy cylinder one past the official number of cylinders
+	 * in the table to mark no-cylinder surface interavals. This is horrendous. Fix ASAP. */
+	// if (idx < 0 || idx >= d->cylinders.nr) {
+	if (idx < 0 || idx >= d->cylinders.nr + 1 || idx >= d->cylinders.allocated) {
 		fprintf(stderr, "Warning: accessing invalid cylinder %d (%d existing)\n", idx, d->cylinders.nr);
 		return NULL;
 	}
diff --git a/core/planner.c b/core/planner.c
index 8cadaca01..f4fb9ee80 100644
--- a/core/planner.c
+++ b/core/planner.c
@@ -272,7 +272,11 @@ static void create_dive_from_plan(struct diveplan *diveplan, struct dive *dive,
 		if (dp->cylinderid != lastcylid) {
 			/* need to insert a first sample for the new gas */
 			add_gas_switch_event(dive, dc, lasttime + 1, dp->cylinderid);
-			cyl = get_or_create_cylinder(dive, dp->cylinderid);
+			cyl = get_cylinder(dive, dp->cylinderid); // FIXME: This actually may get one past the last cylinder for "surface air".
+			if (!cyl) {
+				report_error("Invalid cylinder in create_dive_from_plan(): %d", dp->cylinderid);
+				continue;
+			}
 			sample = prepare_sample(dc);
 			sample[-1].setpoint.mbar = po2;
 			sample->time.seconds = lasttime + 1;
@@ -1070,12 +1074,12 @@ bool plan(struct deco_state *ds, struct diveplan *diveplan, struct dive *dive, i
 	}
 
 	if (prefs.surface_segment != 0) {
-		// Switch to an empty air cylinder for breathing air at the surface
-		// If no empty cylinder is found, keep using last deco gas
-		cylinder_t cyl = empty_cylinder;
-		cyl.cylinder_use = NOT_USED;
-		add_cylinder(&dive->cylinders, dive->cylinders.nr, cyl);
-		current_cylinder = dive->cylinders.nr - 1;
+		// Switch to an empty air cylinder for breathing air at the surface.
+		// FIXME: This is incredibly silly and emulates the old code when
+		// we had a fixed cylinder table: It uses an extra fake cylinder
+		// past the regular cylinder table, which is not visible to the UI.
+		// Fix this as soon as possible!
+		current_cylinder = dive->cylinders.nr;
 		plan_add_segment(diveplan, prefs.surface_segment, 0, current_cylinder, 0, false, OC);
 	}
 	create_dive_from_plan(diveplan, dive, is_planner);