Add zero length arrays (#28)

src/array.c

@@ -34,7 +34,8 @@ struct internal_array {
 /**
  * Initializes an array.
  *
- * @param element_count the amount of elements in the array; must be positive
+ * @param element_count the amount of elements in the array; must not be
+ *                      negative
  * @param data_size     the size of each element in the array; must be positive
  *
  * @return the newly-initialized array, or NULL if memory allocation error
@@ -42,7 +43,7 @@ struct internal_array {
 array array_init(const int element_count, const size_t data_size)
 {
     struct internal_array *init;
-    if (element_count <= 0 || data_size == 0) {
+    if (element_count < 0 || data_size == 0) {
         return NULL;
     }
     init = malloc(sizeof(struct internal_array));
@@ -51,6 +52,10 @@ array array_init(const int element_count, const size_t data_size)
     }
     init->bytes_per_item = data_size;
     init->item_count = element_count;
+    if (init->item_count == 0) {
+        init->data = NULL;
+        return init;
+    }
     init->data = calloc((size_t) element_count, data_size);
     if (!init->data) {
         free(init);
@@ -79,6 +84,9 @@ int array_size(array me)
  */
 void array_copy_to_array(void *const arr, array me)
 {
+    if (me->item_count == 0) {
+        return;
+    }
     memcpy(arr, me->data, me->item_count * me->bytes_per_item);
 }
 

tst/array.c

@@ -7,6 +7,7 @@ void test_array(void)
     int i;
     int *data;
     int arr[10] = {0};
+    int array[2] = {0xdeadbeef, 0xdeadbeef};
     int get;
     assert(!array_init(-1, sizeof(int)));
     assert(!array_init(1, 0));
@@ -42,4 +43,13 @@ void test_array(void)
     assert(array_get(&get, me, -1) == -EINVAL);
     me = array_destroy(me);
     assert(!me);
+    me = array_init(0, sizeof(int));
+    assert(array_size(me) == 0);
+    array_copy_to_array(array, me);
+    assert(array[0] == 0xdeadbeef);
+    assert(array[1] == 0xdeadbeef);
+    assert(!array_get_data(me));
+    assert(array_set(me, 0, &get) == -EINVAL);
+    assert(array_get(&get, me, 0) == -EINVAL);
+    assert(!array_destroy(me));
 }