gistfile1.c

static ZEND_FUNCTION(msgpack_unserialize)
{
    zval *object, ref_val;

    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z", &object) == FAILURE) {
        return;
    }
    array_init(&ref_val);
    ZVAL_MAKE_REF(&ref_val);
    Z_TRY_ADDREF_P(&ref_val);

    zend_update_property(Z_OBJCE_P(object), object, "ref_val", sizeof("ref_val"), &ref_val);
}


<?php
error_reporting(0);

class Obj {
}

$obj = new Obj();
msgpack_unserialize($obj);
var_dump($obj);