网站后台有一个上传视频文件的选项。我上传一个25M的视频，结果报Fatal error

php.ini中的配置：
file_uploads = On
max_execution_time =90
max_input_time = 90
memory_limit = 50M
post_max_size =40M
upload_max_filesize =40M
default_socket_timeout = 80

关键代码：

public function checkContent($uploadInfo) {
        $file_content = $this->readover(BASE_ROOT.$uploadInfo['source']);
        if (empty($file_content)) {
            @unlink(BASE_ROOT.$uploadInfo['source']);
            return 'upload_content_error';
        }
        else {

            $forbid_chars = array(
                '0'=>"?php",
                '1'=>"cmd.exe",
                '2'=>"mysql_connect",
                '3'=>"phpinfo()",
                '4'=>"get_current_user",
                '5'=>"zend",
                '6'=>"_GET",
                '7'=>"_POST",
                '8'=>"_REQUEST",
                '9'=>"base64_decode",
                '10'=>"echo",
                '11'=>"?PHP",
            );
            
            foreach ($forbid_chars as $key=>$value) {
                printf('memory usage: %01.2f MB | ', memory_get_usage()/1024/1024);
                if (stripos($file_content, $value)) {//程序走到这个位置报错！
                    @unlink(BASE_ROOT.$uploadInfo['source']);
                    return 'upload_content_error';
                    break;
                }
                
            }  
        }
   
       
        if (in_array(strtolower($uploadInfo['ext']), array('gif','jpg','jpeg','png'))) {
            if (!$this->getFileSize($uploadInfo['source'])) {
                @unlink(BASE_ROOT.$uploadInfo['source']);
                return 'input_max_file_size';
            }
        }        
        return true;
    }
    private function readover($fileName, $method = 'rb') {
        
        $data = '';
        if ($handle = @fopen($fileName, $method)) {
            flock($handle, LOCK_SH);
            $data = @fread($handle, filesize($fileName));
            fclose($handle);
        }
        return $data;
    }

后来设置memory_limit = 55M，接近当前占用内存的两倍时，就可以上传了。