上传excel文件，怎么解决wps的excel验证不通过的问题 [ 2.0 版本 ]

上传文件处理的UploadForm.php

<?php
namespace common\models;

use yii\base\Model;
use common\helpers\CommonFun;

class UploadForm extends Model
{
    const UPLOAD_FILE = 'file';//上传文件
    const UPLOAD_IMAGE = 'image';//上传图片

    public $inputFile;
    public $imageFile;

    public function scenarios()
    {
        return [
            self::UPLOAD_FILE => ['inputFile'],
            self::UPLOAD_IMAGE => ['imageFile'],
        ];
    }

    public function rules()
    {
        return [
            [
                ['inputFile'],
                'file',
                'skipOnEmpty' => false,
                'extensions' => ['txt', 'zip', 'pdf', 'doc', 'docx', 'ppt', 'pptx', 'xls', 'xlsx', '7z', 'gz'],
                'on' => 'file'
            ],
            [
                ['imageFile'],
                'image',
                'skipOnEmpty' => false,
                'extensions' => 'png, jpg, gif, jpeg',
                'on' => 'image'
            ],
        ];
    }

    /**
     * upload file
     * @author 
     * @dateTime 2017-05-04T19:28:13+0800
     * @param    string $target the upload directory
     * @param    string $fileName the uploaded file name
     * @return   mix
     */
    public function upload($target = NULL,$fileName = NULL)
    {
        if ($this->validate()) {
            //$target = $target ? $target :  Yii::getAlias('@uploads') . '/'. date("Ym");
            if ($this->inputFile != NULL) {
                $extension = $this->inputFile->extension;
            } else {
                $extension = $this->imageFile->extension;
            }
            $target = $target ? $target : $this->setDefaultUploadDir($extension);
            $dir = getcwd() . '/' . $target;
            if(!file_exists($target)) {
                CommonFun::recursionMkDir($target);
            }
            $fileName = $fileName ? $fileName : CommonFun::createUniqueStr();
            $saveName = $dir . '/' . $fileName . '.' . $extension;
            if($this->inputFile != NULL) {
                $this->inputFile->saveAs($saveName);
            } else {
                $this->imageFile->saveAs($saveName);
            }
            $resultUrl = $target . '/' . $fileName . '.' . $extension;
            return $resultUrl;
        } else {
            return false;
        }
    }

    /**
     * 设置默认的上传目录
     * 根据各个应用生成目录
     * @author 
     * @dateTime 2017-05-24T09:21:38+0800
     * @return string 上传路径
     */
    public function setDefaultUploadDir($extension = NULL)
    {
        $uploadDir = "uploads/" . date("Ym");
        if ($extension) {
            $uploadDir .= '/'. $extension;
        }
        if(!file_exists($uploadDir)) {
            CommonFun::recursionMkDir($uploadDir);
        }
        return $uploadDir;
    }
}

上传文件为test.xlsx
wps版的mimeType为application/octet-stream
office版的mimeType为application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
yii的验证机制是根据上传文件的mimeType来匹配对应的extension列表，然而xlsx已经被使用了，我不能再加个xlsx的键值对
在不改源码的基础上怎么让wps文件通过FileValidator的验证