升级到PHP 5.2.2后，出现session_start写入权限问题。

提示信息如下：

Warning: session_start() [function.session-start]: SAFE MODE Restriction in effect. The script whose uid is 2023 is not allowed to access /var/tmp/ owned by uid 0 in /configs/config.inc.php on line 9

Fatal error: session_start() [<a href='function.session-start'>function.session-start</a>]: Failed to initialize storage module: files (path: ) in /configs/config.inc.php on line 9

 

 后来在php5的changelog里找到一个bug报告。里面提到一个安全模式的bug。默认session的save_path是/var/tmp，这样会要校验权限。在php.ini文件里，显式指定session的save_path为/tmp，重启web服务就解决了。