Add some missing assertions

Author: saxbophone

saxbospiral/render.c

@@ -39,14 +39,16 @@ extern "C"{
  * 2-item-long array of type co_ord_t, find and store the co-ords for the
  * corners of the square needed to contain the points.
  * NOTE: This should NEVER be called with a pointer to anything other than a
- * 2-item struct of type co_ord_t
+ * 2-item array of type co_ord_t
  *
  * Asserts:
  * - That spiral.co_ord_cache.co_ords.items is not NULL
+ * - That bounds is not NULL
  */
 static void get_bounds(sxbp_spiral_t spiral, sxbp_co_ord_t* bounds) {
     // preconditional assertions
     assert(spiral.co_ord_cache.co_ords.items != NULL);
+    assert(bounds != NULL);
     sxbp_tuple_item_t min_x = 0;
     sxbp_tuple_item_t min_y = 0;
     sxbp_tuple_item_t max_x = 0;

saxbospiral/render_backends/png_backend.c

@@ -20,6 +20,7 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -83,10 +84,17 @@ static void cleanup_png_lib(
  * given a bitmap_t struct and a pointer to a blank buffer_t, write the bitmap
  * data as a PNG image to the buffer, using libpng.
  * returns a status struct containing error information, if any
+ *
+ * Asserts:
+ * - That bitmap.pixels is not NULL
+ * - That buffer->bytes is NULL
  */
 sxbp_status_t sxbp_write_png_image(
     sxbp_bitmap_t bitmap, sxbp_buffer_t* buffer
 ) {
+    // preconditional assertsions
+    assert(bitmap.pixels != NULL);
+    assert(buffer->bytes == NULL);
     // result status
     sxbp_status_t result;
     // init buffer

saxbospiral/render_backends/png_backend.h

@@ -35,6 +35,10 @@ extern "C"{
  * given a bitmap_t struct and a pointer to a blank buffer_t, write the bitmap
  * data as a PNG image to the buffer, using libpng.
  * returns a status struct containing error information, if any
+ *
+ * Asserts:
+ * - That bitmap.pixels is not NULL
+ * - That buffer->bytes is NULL
  */
 sxbp_status_t sxbp_write_png_image(sxbp_bitmap_t bitmap, sxbp_buffer_t* buffer);