Made necessary changes to get interop tests working

src/php/ext/grpc/byte_buffer.c

@@ -57,6 +57,11 @@ grpc_byte_buffer *string_to_byte_buffer(char *string, size_t length) {
 
 void byte_buffer_to_string(grpc_byte_buffer *buffer, char **out_string,
                            size_t *out_length) {
+  if (buffer == NULL) {
+    *out_string = NULL;
+    *out_length = 0;
+    return;
+  }
   size_t length = grpc_byte_buffer_length(buffer);
   char *string = ecalloc(length + 1, sizeof(char));
   size_t offset = 0;

src/php/ext/grpc/call.c

@@ -448,8 +448,12 @@ PHP_METHOD(Call, start_batch) {
         break;
       case GRPC_OP_RECV_MESSAGE:
         byte_buffer_to_string(message, &message_str, &message_len);
+        if (message_str == NULL) {
+          add_property_null(result, "message");
+        } else {
           add_property_stringl(result, "message", message_str, message_len,
                                false);
+        }
         break;
       case GRPC_OP_RECV_STATUS_ON_CLIENT:
         MAKE_STD_ZVAL(recv_status);
@@ -478,9 +482,20 @@ cleanup:
   RETURN_DESTROY_ZVAL(result);
 }
 
+/**
+ * Cancel the call. This will cause the call to end with STATUS_CANCELLED if it
+ * has not already ended with another status.
+ */
+PHP_METHOD(Call, cancel) {
+  wrapped_grpc_call *call =
+      (wrapped_grpc_call *)zend_object_store_get_object(getThis() TSRMLS_CC);
+  grpc_call_cancel(call->wrapped);
+}
+
 static zend_function_entry call_methods[] = {
     PHP_ME(Call, __construct, NULL, ZEND_ACC_PUBLIC | ZEND_ACC_CTOR)
-    PHP_ME(Call, start_batch, NULL, ZEND_ACC_PUBLIC) PHP_FE_END};
+    PHP_ME(Call, start_batch, NULL, ZEND_ACC_PUBLIC)
+    PHP_ME(Call, cancel, NULL, ZEND_ACC_PUBLIC) PHP_FE_END};
 
 void grpc_init_call(TSRMLS_D) {
   zend_class_entry ce;

src/php/tests/interop/interop_client.php

@@ -132,8 +132,6 @@ function serverStreaming($stub) {
   }
 
   $call = $stub->StreamingOutputCall($request);
-  hardAssert($call->getStatus()->code === Grpc\STATUS_OK,
-              'Call did not complete successfully');
   $i = 0;
   foreach($call->responses() as $value) {
     hardAssert($i < 4, 'Too many responses');
@@ -142,7 +140,10 @@ function serverStreaming($stub) {
                 'Payload ' . $i . ' had the wrong type');
     hardAssert(strlen($payload->getBody()) === $sizes[$i],
                 'Response ' . $i . ' had the wrong length');
+    $i += 1;
   }
+  hardAssert($call->getStatus()->code === Grpc\STATUS_OK,
+             'Call did not complete successfully');
 }
 
 /**
@@ -240,4 +241,6 @@ switch($args['test_case']) {
     break;
   case 'cancel_after_first_response':
     cancelAfterFirstResponse($stub);
+  default:
+    exit(1);
 }