Fix dstr_own() when the dstr already holds a string.

src/dstr.c

@@ -176,7 +176,7 @@ void uc_dstr_own(struct DStr *str, char *restrict s)
     size_t len = strlen(s);
 
     if (str->str) {
-        free(str);
+        free(str->str);
     }
 
     str->len = len;

test/test_dstr.c

@@ -63,9 +63,20 @@ START_TEST (test_dstr_init)
     ck_assert_int_eq(rc, 0);
     ck_assert_int_eq(str.len, 2);
     ck_assert_str_eq(uc_dstr_str(&str), "He");
+    uc_dstr_destroy(&str);
 
 END_TEST
 
+START_TEST (test_dstr_own)
+    struct DStr str;
+
+    uc_dstr_init_str(&str, "init");
+    uc_dstr_own(&str, strdup("Hello !"));
+    ck_assert_int_eq(str.len, 7);
+    ck_assert_str_eq(uc_dstr_str(&str), "Hello !");
+
+    uc_dstr_destroy(&str);
+END_TEST
 START_TEST (test_dstr_own_steal)
     struct DStr str;
     char *s;
@@ -192,6 +203,7 @@ Suite *dstr_suite(void)
     TCase *tc = tcase_create("dstr tests");
     tcase_add_test(tc, test_dstr_basics);
     tcase_add_test(tc, test_dstr_init);
+    tcase_add_test(tc, test_dstr_own);
     tcase_add_test(tc, test_dstr_own_steal);
     tcase_add_test(tc, test_dstr_trim);
     tcase_add_test(tc, test_dstr_replace);