1 files changed, 37 insertions, 5 deletions

diff --git a/src/stage.c b/src/stage.c
index 806b633..a9a5829 100644
--- a/src/stage.c
+++ b/src/stage.c
@@ -14,6 +14,7 @@
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -40,6 +41,9 @@ struct stage_t {
 /* minimally initialize a stage to carry an object */
 static void _stage_set_object(stage_t *stage, const char *name, void *object, stage_render_func_t render_func, stage_free_func_t free_func)
 {
+	assert(stage);
+	assert(name);
+
 	strncpy(stage->name, name, sizeof(stage->name));
 	stage->render = render_func;
 	stage->free = free_func;
@@ -69,6 +73,8 @@ static stage_t * _stage_new(const char *name, void *object, stage_render_func_t
 /* free a stage, no list manipulation occurs, this is purely cleanup of the stage and its object */
 static void _stage_free(stage_t *stage)
 {
+	assert(stage);
+
 	if (stage->free)
 		stage->free(stage, stage->object);
 
@@ -82,6 +88,9 @@ stage_t * stage_new(stage_t *parent, int layer, const char *name, void *object,
 {
 	stage_t	*stage;
 
+	assert(parent || !layer);
+	assert(layer < STAGE_LAYERS_MAX);
+
 	stage = _stage_new(name, object, render_func, free_func);
 	if (!stage)
 		return NULL;
@@ -98,12 +107,16 @@ stage_t * stage_new(stage_t *parent, int layer, const char *name, void *object,
 /* replace a given stage's object only - retain render/free hooks and everything else, invalidates cache  - DOES NOT FREE OLD OBJECT */
 void stage_set_object(stage_t *stage, void *object)
 {
+	assert(stage);
+
 	stage->object = object;
 }
 
 
 void stage_get_object(const stage_t *stage, void **res_object)
 {
+	assert(stage);
+
 	*res_object = stage->object;
 }
 
@@ -111,6 +124,8 @@ void stage_get_object(const stage_t *stage, void **res_object)
 /* replaces a given stage's object-related properties but otherwise keeping the existing state */
 void stage_replace(stage_t *stage, const char *name, void *object, stage_render_func_t render_func, stage_free_func_t free_func)
 {
+	assert(stage);
+
 	if (stage->free)
 		stage->free(stage, stage->object);
 
@@ -124,6 +139,8 @@ static void _stage_free_all(stage_t *stage, int force);
 /* recursively free the layers of this stage, but not the stage itself */
 static void _stage_free_layers(stage_t *stage, int force)
 {
+	assert(stage);
+
 	for (int i = 0; i < STAGE_LAYERS_MAX; i++) {
 		stage_t	*s, *_s;
 
@@ -136,6 +153,8 @@ static void _stage_free_layers(stage_t *stage, int force)
 /* free the stage recursively, skipping locked stages if !force */
 static void _stage_free_all(stage_t *stage, int force)
 {
+	assert(stage);
+
 	if (stage->locked && !force)
 		return;
 
@@ -160,6 +179,8 @@ stage_t * stage_free(stage_t *stage)
 /* set the alpha on a stage */
 void stage_set_alpha(stage_t *stage, float alpha)
 {
+	assert(stage);
+
 	stage->alpha = alpha;
 }
 
@@ -167,6 +188,8 @@ void stage_set_alpha(stage_t *stage, float alpha)
 /* set a stage's active state (participates in rendering) */
 void stage_set_active(stage_t *stage, int active)
 {
+	assert(stage);
+
 	stage->active = active;
 }
 
@@ -174,6 +197,8 @@ void stage_set_active(stage_t *stage, int active)
 /* set a stage's locked state (doesn't get freed by clears) */
 void stage_set_locked(stage_t *stage, int locked)
 {
+	assert(stage);
+
 	stage->locked = locked;
 }
 
@@ -182,11 +207,11 @@ void stage_set_locked(stage_t *stage, int locked)
 /* TODO: maybe support supplying a parent here for switching parents? */
 void stage_set_layer(stage_t *stage, int layer)
 {
-	/* TODO: assert parent, and layer sanity */
-	if (stage->parent) {
-		(void) dll_del(&stage->layer);
-		(void) dll_add_pre(&stage->parent->layers[layer], &stage->layer);
-	}
+	assert(stage);
+	assert(stage->parent);
+
+	(void) dll_del(&stage->layer);
+	(void) dll_add_pre(&stage->parent->layers[layer], &stage->layer);
 }
 
 
@@ -226,6 +251,8 @@ static void _render_stage(const stage_t *stage, float alpha)
 {
 	float	a = alpha * stage->alpha;
 
+	assert(stage);
+
 	if (stage->render)
 		stage->render(stage, stage->object, a);
 
@@ -245,6 +272,8 @@ static void _render_stage(const stage_t *stage, float alpha)
 /* recursively render the supplied stage tree, skipping inactive branches */
 void stage_render(const stage_t *stage)
 {
+	assert(stage);
+
 	if (!stage->active)
 		return;
 
@@ -255,6 +284,9 @@ void stage_render(const stage_t *stage)
 /* lookup a stage from a name, returns first match */
 stage_t * stage_lookup_name(stage_t *stage, const char *name)
 {
+	assert(stage);
+	assert(name);
+
 	if (!strncmp(stage->name, name, sizeof(stage->name)))
 		return stage;