return FAILURE;
                                break;
        
                        case 3:         /*save to a file */
                                 stream = php_stream_open_wrapper(opt, "a", IGNORE_URL_WIN |  
ENFORCE_SAFE_MODE | REPORT_ERRORS, NULL);
                                if (!stream) {
                                        return FAILURE;
                                }
                                php_stream_write(stream, message, message_len);
                                php_stream_close(stream);
                                break;
        
                        case 4: /* send to SAPI */
                                if (sapi_module.log_message) {
                                        sapi_module.log_message(message);
                                } else {
                                        return FAILURE;
                                }
                                break;
        
                        default:
                                php_log_err(message TSRMLS_CC);
                                break;
                }
                return SUCCESS;
        }
　　case 1:php_mail 函数会根据我们 php.ini 里面 sendmail_path 的配置来发送邮件;
　　case 2:这个就不说了，我从来没用过
　　case 3:通过 IO 函数写入到文件中。
　　case 4:这个可以通过 sapi 接口记录我们的日志内容
　　default: 

 

根据 error_log 的配置，将日志写到该文件中。。