Invoke headers callback when CopyObject request is bypassed (#180)

* Invoke headers callback when CopyObject request is bypassed

Prior to this fix the headers callback was invoked only
when the Copy meta request performed a multi-part copy, but not
when the object was small and resulted in a bypassed CopyObject request.

This commit fixes the issue, invoking the headers callback
in both cases.

source/s3_copy_object.c

@@ -594,8 +594,32 @@ static void s_s3_copy_object_request_finished(
             break;
         }
 
+        /* The S3 object is not large enough for multi-part copy. A copy of the original CopyObject request
+         * was bypassed to S3 and is now finished. */
         case AWS_S3_COPY_OBJECT_REQUEST_TAG_BYPASS: {
 
+            /* Invoke headers callback if it was requested for this meta request */
+            if (meta_request->headers_callback != NULL) {
+                struct aws_http_headers *final_response_headers = aws_http_headers_new(meta_request->allocator);
+
+                /* Copy all the response headers from this request. */
+                copy_http_headers(request->send_data.response_headers, final_response_headers);
+
+                /* Notify the user of the headers. */
+                if (meta_request->headers_callback(
+                        meta_request,
+                        final_response_headers,
+                        request->send_data.response_status,
+                        meta_request->user_data)) {
+
+                    error_code = aws_last_error_or_unknown();
+                }
+                meta_request->headers_callback = NULL;
+
+                aws_http_headers_release(final_response_headers);
+            }
+
+            /* Signals completion of the meta request */
             if (error_code == AWS_ERROR_SUCCESS) {
                 copy_object->synced_data.copy_request_bypass_completed = true;
             } else {
@@ -744,6 +768,7 @@ static void s_s3_copy_object_request_finished(
 
                     error_code = aws_last_error_or_unknown();
                 }
+                meta_request->headers_callback = NULL;
 
                 aws_http_headers_release(final_response_headers);
             }

tests/s3_data_plane_tests.c

@@ -3498,6 +3498,7 @@ struct copy_object_test_data {
     struct aws_mutex mutex;
     struct aws_condition_variable c_var;
     bool execution_completed;
+    bool headers_callback_was_invoked;
     int meta_request_error_code;
     int response_status_code;
 };
@@ -3528,6 +3529,25 @@ static void s_copy_object_meta_request_finish(
     aws_condition_variable_notify_one(&test_data->c_var);
 }
 
+static int s_copy_object_meta_request_headers_callback(
+    struct aws_s3_meta_request *meta_request,
+    const struct aws_http_headers *headers,
+    int response_status,
+    void *user_data) {
+
+    (void)meta_request;
+    (void)headers;
+    (void)response_status;
+
+    struct copy_object_test_data *test_data = user_data;
+
+    aws_mutex_lock(&test_data->mutex);
+    test_data->headers_callback_was_invoked = true;
+    aws_mutex_unlock(&test_data->mutex);
+
+    return AWS_OP_SUCCESS;
+}
+
 static bool s_copy_test_completion_predicate(void *arg) {
     struct copy_object_test_data *test_data = arg;
     return test_data->execution_completed;
@@ -3578,7 +3598,7 @@ static int s_test_s3_copy_object_from_x_amz_copy_source(
         .body_callback = NULL,
         .signing_config = client_config.signing_config,
         .finish_callback = s_copy_object_meta_request_finish,
-        .headers_callback = NULL,
+        .headers_callback = s_copy_object_meta_request_headers_callback,
         .message = message,
         .shutdown_callback = NULL,
         .type = AWS_S3_META_REQUEST_TYPE_COPY_OBJECT,
@@ -3596,6 +3616,9 @@ static int s_test_s3_copy_object_from_x_amz_copy_source(
     ASSERT_INT_EQUALS(expected_error_code, test_data.meta_request_error_code);
     ASSERT_INT_EQUALS(expected_response_status, test_data.response_status_code);
 
+    /* assert headers callback was invoked */
+    ASSERT_TRUE(test_data.headers_callback_was_invoked);
+
     aws_s3_meta_request_release(meta_request);
     aws_mutex_clean_up(&test_data.mutex);
     aws_http_message_destroy(message);