static
struct PP_Var
trace_ppb_url_util_dev_resolve_relative_to_document(PP_Instance instance,
                                                    struct PP_Var relative_string,
                                                    struct PP_URLComponents_Dev *components)
{
    trace_info("[PPB] {full} %s\n", __func__+6);
    return ppb_url_util_dev_resolve_relative_to_document(instance, relative_string, components);
}
int32_t
ppb_url_loader_open_target(PP_Resource loader, PP_Resource request_info,
                           struct PP_CompletionCallback callback, const char *target)
{
    struct pp_url_loader_s *ul = pp_resource_acquire(loader, PP_RESOURCE_URL_LOADER);
    if (!ul) {
        trace_error("%s, bad resource\n", __func__);
        return PP_ERROR_BADRESOURCE;
    }
    struct pp_url_request_info_s *ri = pp_resource_acquire(request_info,
                                                           PP_RESOURCE_URL_REQUEST_INFO);
    if (!ri) {
        trace_error("%s, bad resource\n", __func__);
        pp_resource_release(loader);
        return PP_ERROR_BADRESOURCE;
    }
    struct PP_Var full_url;

    if (ri->is_immediate_javascript) {
        full_url = ppb_var_var_from_utf8_z(ri->url);
    } else {
        struct PP_Var rel_url = ppb_var_var_from_utf8_z(ri->url);
        full_url = ppb_url_util_dev_resolve_relative_to_document(ul->instance->id, rel_url, NULL);
        ppb_var_release(rel_url);
    }

    ul->url =              nullsafe_strdup(ppb_var_var_to_utf8(full_url, NULL));
    ul->method =           ri->method;
    ul->read_pos =         0;
    ul->request_headers =  nullsafe_strdup(ri->headers);
    ul->follow_redirects = ri->follow_redirects;
    ul->stream_to_file =   ri->stream_to_file;

    ul->record_download_progress =         ri->record_download_progress;
    ul->record_upload_progress =           ri->record_upload_progress;
    ul->custom_referrer_url =              nullsafe_strdup(ri->custom_referrer_url);
    ul->allow_cross_origin_requests =      ri->allow_cross_origin_requests;
    ul->allow_credentials =                ri->allow_credentials;
    ul->custom_content_transfer_encoding = nullsafe_strdup(ri->custom_content_transfer_encoding);
    ul->custom_user_agent =                nullsafe_strdup(ri->custom_user_agent);
    ul->target =                           nullsafe_strdup(target);

#define TRIM_NEWLINE(s)     s = trim_nl(s)

    TRIM_NEWLINE(ul->request_headers);
    TRIM_NEWLINE(ul->custom_referrer_url);
    TRIM_NEWLINE(ul->custom_content_transfer_encoding);
    TRIM_NEWLINE(ul->custom_user_agent);

    ul->post_len = ri->post_len;
    if (ri->post_len > 0) {
        ul->post_data = malloc(ri->post_len);
        memcpy(ul->post_data, ri->post_data, ri->post_len);
    }

    ul->fd = open_temporary_file();
    ul->ccb = callback;

    ppb_var_release(full_url);
    pp_resource_release(request_info);

    struct url_loader_open_param_s *p = g_slice_alloc(sizeof(*p));
    p->url =                ul->url;
    p->loader =             loader;
    p->instance_id =        ul->instance->id;
    p->method =             ul->method;
    p->request_headers =    ul->request_headers;
    p->custom_referrer_url = ul->custom_referrer_url;
    p->custom_content_transfer_encoding = ul->custom_content_transfer_encoding;
    p->custom_user_agent =  ul->custom_user_agent;
    p->target =         ul->target;
    p->post_len =       ul->post_len;
    p->post_data =      ul->post_data;
    p->m_loop =         ppb_message_loop_get_current();
    p->depth =          ppb_message_loop_get_depth(p->m_loop) + 1;

    ppb_core_add_ref_resource(loader);  // add ref to ensure data in ul remain accessible
    pp_resource_release(loader);

    ppb_message_loop_post_work(p->m_loop, PP_MakeCCB(_url_loader_open_comt, p), 0);
    ppb_message_loop_run_nested(p->m_loop);
    ppb_core_release_resource(loader);
    
    int retval = p->retval;
    g_slice_free1(sizeof(*p), p);

    if (retval != NPERR_NO_ERROR)
        return PP_ERROR_FAILED;

    if (callback.func == NULL) {
        int done = 0;
        while (!done) {
            ul = pp_resource_acquire(loader, PP_RESOURCE_URL_LOADER);
            if (ul) {
                done = ul->finished_loading;
                pp_resource_release(loader);
            } else {
                break;
            }
            printf("waitin'\n");
            usleep(10000);
        }
        return PP_OK;
    }

    return PP_OK_COMPLETIONPENDING;
}