Cylinders: access cylinders with get_cylinder()

Instead of accessing the cylinder table directly, use the get_cylinder()
function. This gives less unwieldy expressions. But more importantly,
the function does bound checking. This is crucial for now as the code
hasn't be properly audited since the change to arbitrarily sized
cylinder tables. Accesses of invalid cylinder indexes may lead to
silent data-corruption that is sometimes not even noticed by
valgrind. Returning NULL instead of an invalid pointer will make
debugging much easier.

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

1 files changed, 8 insertions, 8 deletions

diff --git a/core/profile.c b/core/profile.c
index 4d35155b2..bee2b7a4a 100644
--- a/core/profile.c
+++ b/core/profile.c
@@ -189,7 +189,7 @@ static int get_local_sac(struct plot_info *pi, int idx1, int idx2, struct dive *
 	depth = (entry1->depth + entry2->depth) / 2;
 	atm = depth_to_atm(depth, dive);
 
-	cyl = dive->cylinders.cylinders + index;
+	cyl = get_cylinder(dive, index);
 
 	airuse = gas_volume(cyl, a) - gas_volume(cyl, b);
 
@@ -414,7 +414,7 @@ static void calculate_max_limits_new(struct dive *dive, struct divecomputer *giv
 
 	/* Get the per-cylinder maximum pressure if they are manual */
 	for (cyl = 0; cyl < dive->cylinders.nr; cyl++) {
-		int mbar = dive->cylinders.cylinders[cyl].start.mbar;
+		int mbar = get_cylinder(dive, cyl)->start.mbar;
 		if (mbar > maxpressure)
 			maxpressure = mbar;
 		if (mbar < minpressure)
@@ -677,7 +677,7 @@ static int sac_between(struct dive *dive, struct plot_info *pi, int first, int l
 
 		a.mbar = get_plot_pressure(pi, first, i);
 		b.mbar = get_plot_pressure(pi, last, i);
-		cyl = dive->cylinders.cylinders + i;
+		cyl = get_cylinder(dive, i);
 		cyluse = gas_volume(cyl, a) - gas_volume(cyl, b);
 		if (cyluse > 0)
 			airuse += cyluse;
@@ -800,7 +800,7 @@ static void matching_gases(struct dive *dive, struct gasmix gasmix, bool gases[]
 	int i;
 
 	for (i = 0; i < dive->cylinders.nr; i++)
-		gases[i] = same_gasmix(gasmix, dive->cylinders.cylinders[i].gasmix);
+		gases[i] = same_gasmix(gasmix, get_cylinder(dive, i)->gasmix);
 }
 
 static void calculate_sac(struct dive *dive, struct divecomputer *dc, struct plot_info *pi)
@@ -890,7 +890,7 @@ static void setup_gas_sensor_pressure(const struct dive *dive, const struct dive
 	// Fill in "seen[]" array - mark cylinders we're not interested
 	// in as negative.
 	for (i = 0; i < pi->nr_cylinders; i++) {
-		const cylinder_t *cyl = dive->cylinders.cylinders + i;
+		const cylinder_t *cyl = get_cylinder(dive, i);
 		int start = cyl->start.mbar;
 		int end = cyl->end.mbar;
 
@@ -920,7 +920,7 @@ static void setup_gas_sensor_pressure(const struct dive *dive, const struct dive
 
 	for (i = 0; i < pi->nr_cylinders; i++) {
 		if (seen[i] >= 0) {
-			const cylinder_t *cyl = dive->cylinders.cylinders + i;
+			const cylinder_t *cyl = get_cylinder(dive, i);
 
 			add_plot_pressure(pi, first[i], i, cyl->start);
 			add_plot_pressure(pi, last[i], i, cyl->end);
@@ -1442,7 +1442,7 @@ static void plot_string(struct plot_info *pi, int idx, struct membuffer *b)
 		int mbar = get_plot_pressure(pi, idx, cyl);
 		if (!mbar)
 			continue;
-		struct gasmix mix = displayed_dive.cylinders.cylinders[cyl].gasmix;
+		struct gasmix mix = get_cylinder(&displayed_dive, cyl)->gasmix;
 		pressurevalue = get_pressure_units(mbar, &pressure_unit);
 		put_format_loc(b, translate("gettextFromC", "P: %d%s (%s)\n"), pressurevalue, pressure_unit, gasname(mix));
 	}
@@ -1706,7 +1706,7 @@ void compare_samples(struct plot_info *pi, int idx1, int idx2, char *buf, int bu
 		pressurevalue = get_pressure_units(bar_used, &pressure_unit);
 		memcpy(buf2, buf, bufsize);
 		snprintf_loc(buf, bufsize, translate("gettextFromC", "%s ΔP:%d%s"), buf2, pressurevalue, pressure_unit);
-		cylinder_t *cyl = displayed_dive.cylinders.cylinders + 0;
+		cylinder_t *cyl = get_cylinder(&displayed_dive, 0);
 		/* if we didn't cross a tank change and know the cylidner size as well, show SAC rate */
 		if (!crossed_tankchange && cyl->type.size.mliter) {
 			double volume_value;