memory-util: add a concept for gcc cleanup attribute based array destruction

src/test/test-memory-util.c

@@ -15,4 +15,41 @@ TEST(eqzero) {
         assert_se(!eqzero(longer));
 }
 
+static void my_destructor(struct iovec *iov, size_t n) {
+        /* not really a destructor, just something we can use to check if the destruction worked */
+        memset(iov, 'y', sizeof(struct iovec) * n);
+}
+
+TEST(cleanup_array) {
+        struct iovec *iov, *saved_iov;
+        size_t n, saved_n;
+
+        n = 7;
+        iov = new(struct iovec, n);
+        assert_se(iov);
+
+        memset(iov, 'x', sizeof(struct iovec) * n);
+
+        saved_iov = iov;
+        saved_n = n;
+
+        {
+                assert_se(memeqbyte('x', saved_iov, sizeof(struct iovec) * saved_n));
+                assert_se(iov);
+                assert_se(n > 0);
+
+                CLEANUP_ARRAY(iov, n, my_destructor);
+
+                assert_se(memeqbyte('x', saved_iov, sizeof(struct iovec) * saved_n));
+                assert_se(iov);
+                assert_se(n > 0);
+        }
+
+        assert_se(memeqbyte('y', saved_iov, sizeof(struct iovec) * saved_n));
+        assert_se(!iov);
+        assert_se(n == 0);
+
+        free(saved_iov);
+}
+
 DEFINE_TEST_MAIN(LOG_INFO);