Correct multi-edit equipment update logic

I lied in the commit message for commit 0468535524a3 ("When editing multiple
files, don't override existing equipment entries"); the changes there did
not parallel the logic for the string entries. Now I think it does.

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

dive.h

@@ -92,8 +92,11 @@ typedef struct {
 	const char *description;	/* "integrated", "belt", "ankle" */
 } weightsystem_t;
 
-extern int cylinder_none(void *_data);
-extern int weightsystem_none(void *_data);
+extern gboolean cylinder_none(void *_data);
+extern gboolean no_cylinders(cylinder_t *cyl);
+extern gboolean cylinders_equal(cylinder_t *cyl1, cylinder_t *cyl2);
+extern gboolean no_weightsystems(weightsystem_t *ws);
+extern gboolean weightsystems_equal(weightsystem_t *ws1, weightsystem_t *ws2);
 
 extern int get_pressure_units(unsigned int mb, const char **units);
 extern double get_depth_units(unsigned int mm, int *frac, const char **units);

equipment.c

@@ -428,7 +428,7 @@ static void show_weightsystem(weightsystem_t *ws, struct ws_widget *weightsystem
 	set_weight_weight_spinbutton(weightsystem_widget, ws->weight.grams);
 }
 
-int cylinder_none(void *_data)
+gboolean cylinder_none(void *_data)
 {
 	cylinder_t *cyl = _data;
 	return	!cyl->type.size.mliter &&
@@ -442,12 +442,77 @@ int cylinder_none(void *_data)
 		!cyl->end.mbar;
 }
 
-int weightsystem_none(void *_data)
+gboolean no_cylinders(cylinder_t *cyl)
+{
+	int i;
+
+	for (i = 0; i < MAX_CYLINDERS; i++)
+		if (!cylinder_none(cyl + i))
+			return FALSE;
+	return TRUE;
+}
+
+/* descriptions are equal if they are both NULL or both non-NULL
+   and the same text */
+gboolean description_equal(const char *desc1, const char *desc2)
+{
+		return ((! desc1 && ! desc2) ||
+			(desc1 && desc2 && strcmp(desc1, desc2) == 0));
+}
+
+/* when checking for the same cylinder we want the size and description to match
+   but don't compare the start and end pressures */
+static gboolean one_cylinder_equal(cylinder_t *cyl1, cylinder_t *cyl2)
+{
+	return cyl1->type.size.mliter == cyl2->type.size.mliter &&
+		cyl1->type.workingpressure.mbar == cyl2->type.workingpressure.mbar &&
+		cyl1->gasmix.o2.permille == cyl2->gasmix.o2.permille &&
+		cyl1->gasmix.he.permille == cyl2->gasmix.he.permille &&
+		description_equal(cyl1->type.description, cyl2->type.description);
+}
+
+gboolean cylinders_equal(cylinder_t *cyl1, cylinder_t *cyl2)
+{
+	int i;
+
+	for (i = 0; i < MAX_CYLINDERS; i++)
+		if (!one_cylinder_equal(cyl1 + i, cyl2 + i))
+			return FALSE;
+	return TRUE;
+}
+
+static gboolean weightsystem_none(void *_data)
 {
 	weightsystem_t *ws = _data;
 	return !ws->weight.grams && !ws->description;
 }
 
+gboolean no_weightsystems(weightsystem_t *ws)
+{
+	int i;
+
+	for (i = 0; i < MAX_WEIGHTSYSTEMS; i++)
+		if (!weightsystem_none(ws + i))
+			return FALSE;
+	return TRUE;
+}
+
+static gboolean one_weightsystem_equal(weightsystem_t *ws1, weightsystem_t *ws2)
+{
+	return ws1->weight.grams == ws2->weight.grams &&
+		description_equal(ws1->description, ws2->description);
+}
+
+gboolean weightsystems_equal(weightsystem_t *ws1, weightsystem_t *ws2)
+{
+	int i;
+
+	for (i = 0; i < MAX_WEIGHTSYSTEMS; i++)
+		if (!one_weightsystem_equal(ws1 + i, ws2 + i))
+			return FALSE;
+	return TRUE;
+}
+
 static void set_one_cylinder(void *_data, GtkListStore *model, GtkTreeIter *iter)
 {
 	cylinder_t *cyl = _data;
@@ -493,7 +558,7 @@ static void *ws_ptr(struct dive *dive, int idx)
 static void show_equipment(struct dive *dive, int max,
 			struct equipment_list *equipment_list,
 			void*(*ptr_function)(struct dive*, int),
-			int(*none_function)(void *),
+			gboolean(*none_function)(void *),
 			void(*set_one_function)(void*, GtkListStore*, GtkTreeIter *))
 {
 	int i, used;

info.c

@@ -460,25 +460,33 @@ static void dive_info_widget(GtkWidget *box, struct dive *dive, struct dive_info
 /* we use these to find out if we edited the cylinder or weightsystem entries */
 static cylinder_t remember_cyl[MAX_CYLINDERS];
 static weightsystem_t remember_ws[MAX_WEIGHTSYSTEMS];
+#define CYL_BYTES sizeof(cylinder_t) * MAX_CYLINDERS
+#define WS_BYTES sizeof(weightsystem_t) * MAX_WEIGHTSYSTEMS
 
 void save_equipment_data(struct dive *dive)
 {
 	if (dive) {
-		memcpy(remember_cyl, dive->cylinder, sizeof(cylinder_t) * MAX_CYLINDERS);
-		memcpy(remember_ws, dive->weightsystem, sizeof(weightsystem_t) * MAX_WEIGHTSYSTEMS);
+		memcpy(remember_cyl, dive->cylinder, CYL_BYTES);
+		memcpy(remember_ws, dive->weightsystem, WS_BYTES);
 	}
 }
 
+/* the editing happens on the master dive; we copy the equipment
+   data if it has changed in the master dive and the other dive
+   either has no entries for the equipment or the same entries
+   as the master dive had before it was edited */
 void update_equipment_data(struct dive *dive, struct dive *master)
 {
 	if (dive == master)
 		return;
-	if (memcmp(remember_cyl, master->cylinder, sizeof(cylinder_t) * MAX_CYLINDERS) &&
-		cylinder_none(dive->cylinder))
-		memcpy(dive->cylinder, master->cylinder, sizeof(cylinder_t) * MAX_CYLINDERS);
-	if (memcmp(remember_ws, master->weightsystem, sizeof(weightsystem_t) * MAX_WEIGHTSYSTEMS) &&
-		weightsystem_none(dive->weightsystem))
-		memcpy(dive->weightsystem, master->weightsystem, sizeof(weightsystem_t) * MAX_WEIGHTSYSTEMS);
+	if ( ! cylinders_equal(remember_cyl, master->cylinder) &&
+		(no_cylinders(dive->cylinder) ||
+			cylinders_equal(dive->cylinder, remember_cyl)))
+		memcpy(dive->cylinder, master->cylinder, CYL_BYTES);
+	if (! weightsystems_equal(remember_ws, master->weightsystem) &&
+		(no_weightsystems(dive->weightsystem) ||
+			weightsystems_equal(dive->weightsystem, remember_ws)))
+		memcpy(dive->weightsystem, master->weightsystem, WS_BYTES);
 }
 
 int edit_multi_dive_info(int nr, int *indices)