Check of count or size is 0 in heapsort

src/heapsort.c

@@ -29,9 +29,17 @@ void
 uc_heapsort(void *base_, size_t count, size_t width,
      uc_hs_cmp cmp, uc_hs_swp swap, void *cookie)
 {
-    int start = count / 2 - 1, end = count - 1;
+    long start;
+    long end;
     unsigned char *base = base_;
 
+    if (count == 0 || width == 0) {
+        return;
+    }
+
+    start = count / 2 - 1, 
+    end = count - 1;
+
     while (start >= 0) {
         uc_sift(base, start, count, width, cmp, swap, cookie);
         start--;

test/test_heapsort.c

@@ -81,16 +81,44 @@ START_TEST (test_heapsort_even)
 
     uc_heapsort(unordered, ARRAY_SIZE(unordered), sizeof(struct Stuff), 
                 cmp_stuff, swap_stuff, NULL);
-    print_stuff(unordered, ARRAY_SIZE(unordered));
     fail_if(memcmp(unordered, ordered, sizeof unordered) != 0);
 END_TEST
 
+START_TEST (test_heapsort_zero)
+    struct Stuff unordered[] = {
+        {"1", 1},
+        {"7", 7},
+        {"3", 3},
+        {"4", 4},
+        {"6", 6},
+        {"2", 2},
+    };
+
+    struct Stuff same[] = {
+        {"1", 1},
+        {"7", 7},
+        {"3", 3},
+        {"4", 4},
+        {"6", 6},
+        {"2", 2},
+    };
+
+    uc_heapsort(unordered, 0, sizeof(struct Stuff), 
+                cmp_stuff, swap_stuff, NULL);
+    fail_if(memcmp(unordered, same, sizeof unordered) != 0);
+
+    uc_heapsort(unordered, ARRAY_SIZE(unordered), 0, 
+                cmp_stuff, swap_stuff, NULL);
+    fail_if(memcmp(unordered, same, sizeof unordered) != 0);
+END_TEST
+
 Suite *heapsort_suite(void)
 {
     Suite *s = suite_create("heapsort");
     TCase *tc = tcase_create("heapsort tests");
     tcase_add_test(tc, test_heapsort_odd);
     tcase_add_test(tc, test_heapsort_even);
+    tcase_add_test(tc, test_heapsort_zero);
 
     suite_add_tcase(s, tc);