Fatal error: session_start(): Failed to initialize storage module: files问题解决方法

之前编译安装的lnmp环境+phpmyamdin4.02的版本，今天突然出现这个问题：

fatal error: session_start(): failed to initialize storage module: files (path: ) in /data/www/phpmyadmin/libraries/session.inc.php on line 83

大致意思是session会话初始化的时候储存路径有误！第一反应就是查看php.ini的配置文件中的：

session.save_path = "/tmp"

默认前面是加的分号，表示不启用，我之前配置的时候已经启用了。那为什么还会报错呢？，于是网上找了一些资料，感觉都千篇一律：

1、检查error.log(apache2.2\logs)文件，查看是否有错误报告。未发现。
2、检查php.ini中的session.save_handler的值是否为files，如果不是改为files
3、检查php.ini文件中session.save_path是否被注释了，如果有，则去掉前面的”;”。
4、将save_path后面的路径改成已有的路径，比如”d:\php\temp”
5、检查temp文件夹的属性是否可读可写。
6、重启apache服务器。ok

不知道那些哥们转载的时候自己试过了没有（在这里喷一下，最讨厌那种自己都没有亲测，就一股脑的转来转去。一点都不负责!）
根据上面的流程，排查了之后发现压根就没有解决，不过小编的服务器是nginx非apache。
然后自己写了一个脚本test.php：

$r = session_start();
var_dump($r);

打印结果为：

warning: session_start(): safe mode restriction in effect. the script whose uid is 501 is not allowed to access /tmp owned by uid 0 in /data/www/test.php on line 3 fatal error: session_start(): failed to initialize storage module: files (path: ) in /data/www/test.php on line 3

意思是 php5一个安全模式的bug，默认session的save_path是系统的临时目录，这样会要校验权限。而这个脚本不能通过/tmp拥有者uid为0来执行uid是501也是www用户组的权限
解决这个有两种解决方法：

1.关闭安全模式；
2.在命令行下chown改文件/目录的拥有者

当然两种方法都要求你有服务器的权限。
下面是示例php.ini的配置文件：

[session]
 ; handler used to store/retrieve data.
 ; http://php.net/session.save-handler
session.save_handler = files; argument passed to save_handler.  in the case of files, this is the path
 ; where data files are stored. note: windows users have to change this
 ; variable in order to use php's session functions.

 ; the path can be defined as:

 ;     session.save_path = "n;/path"

 ; where n is an integer.  instead of storing all the session files in
 ; /path, what this will do is use subdirectories n-levels deep, and
 ; store the session data in those directories.  this is useful if you
 ; or your os have problems with lots of files in one directory, and is
 ; a more efficient layout for servers that handle lots of sessions.

 ; note 1: php will not create this directory structure automatically.
 ;         you can use the script in the ext/session dir for that purpose.
 ; note 2: see the section on garbage collection below if you choose to
 ;         use subdirectories for session storage

 ; the file storage module creates files using mode 600 by default.
 ; you can change that by using

 ;     session.save_path = "n;mode;/path"

 ; where mode is the octal representation of the mode. note that this
 ; does not overwrite the process's umask.
 ; http://php.net/session.save-path
 session.save_path = "/tmp"
; whether to use cookies.
 ; http://php.net/session.use-cookies
 session.use_cookies = 1
; http://php.net/session.cookie-secure
 ;session.cookie_secure =
; this option forces php to fetch and use a cookie for storing and maintaining
 ; the session id. we encourage this operation as it's very helpful in combatting
 ; session hijacking when not specifying and managing your own session id. it is
 ; not the end all be all of session hijacking defense, but it's a good start.
 ; http://php.net/session.use-only-cookies
 session.use_only_cookies = 1
; name of the session (used as cookie name).
 ; http://php.net/session.name
 session.name = phpsessid
; initialize session on request startup.
 ; http://php.net/session.auto-start
 session.auto_start = 0
; lifetime in seconds of cookie or, if 0, until browser is restarted.
 ; http://php.net/session.cookie-lifetime
 session.cookie_lifetime = 0
; the path for which the cookie is valid.
 ; http://php.net/session.cookie-path
 session.cookie_path = /
; the domain for which the cookie is valid.
 ; http://php.net/session.cookie-domain
 session.cookie_domain =
; whether or not to add the httponly flag to the cookie, which makes it inaccessible to browser scripting languages such as javascript.
 ; http://php.net/session.cookie-httponly
 session.cookie_httponly =
; handler used to serialize data.  php is the standard serializer of php.
 ; http://php.net/session.serialize-handler
 session.serialize_handler = php
; defines the probability that the 'garbage collection' process is started
 ; on every session initialization. the probability is calculated by using
 ; gc_probability/gc_divisor. where session.gc_probability is the numerator
 ; and gc_divisor is the denominator in the equation. setting this value to 1
 ; when the session.gc_divisor value is 100 will give you approximately a 1% chance
 ; the gc will run on any give request.
 ; default value: 1
 ; development value: 1
 ; production value: 1
 ; http://php.net/session.gc-probability
 session.gc_probability = 1
; defines the probability that the 'garbage collection' process is started on every
 ; session initialization. the probability is calculated by using the following equation:
 ; gc_probability/gc_divisor. where session.gc_probability is the numerator and
 ; session.gc_divisor is the denominator in the equation. setting this value to 1
 ; when the session.gc_divisor value is 100 will give you approximately a 1% chance
 ; the gc will run on any give request. increasing this value to 1000 will give you
 ; a 0.1% chance the gc will run on any give request. for high volume production servers,
 ; this is a more efficient approach.
 ; default value: 100
 ; development value: 1000
 ; production value: 1000
 ; http://php.net/session.gc-divisor
 session.gc_divisor = 1000
; after this number of seconds, stored data will be seen as 'garbage' and
 ; cleaned up by the garbage collection process.
 ; http://php.net/session.gc-maxlifetime
 session.gc_maxlifetime = 1440
; note: if you are using the subdirectory option for storing session files
 ;       (see session.save_path above), then garbage collection does *not*
 ;       happen automatically.  you will need to do your own garbage
 ;       collection through a shell script, cron entry, or some other method.
 ;       for example, the following script would is the equivalent of
 ;       setting session.gc_maxlifetime to 1440 (1440 seconds = 24 minutes):
 ;          find /path/to/sessions -cmin +24 | xargs rm
; php 4.2 and less have an undocumented feature/bug that allows you to
 ; to initialize a session variable in the global scope, even when register_globals
 ; is disabled.  php 4.3 and later will warn you, if this feature is used.
 ; you can disable the feature and the warning separately. at this time,
 ; the warning is only displayed, if bug_compat_42 is enabled. this feature
 ; introduces some serious security problems if not handled correctly. it's
 ; recommended that you do not use this feature on production servers. but you
 ; should enable this on development servers and enable the warning as well. if you
 ; do not enable the feature on development servers, you won't be warned when it's
 ; used and debugging errors caused by this can be difficult to track down.
 ; default value: on
 ; development value: on
 ; production value: off
 ; http://php.net/session.bug-compat-42
 session.bug_compat_42 = off
; this setting controls whether or not you are warned by php when initializing a
 ; session value into the global space. session.bug_compat_42 must be enabled before
 ; these warnings can be issued by php. see the directive above for more information.
 ; default value: on
 ; development value: on
 ; production value: off
 ; http://php.net/session.bug-compat-warn
 session.bug_compat_warn = off
; check http referer to invalidate externally stored urls containing ids.
 ; http_referer has to contain this substring for the session to be
 ; considered as valid.
 ; http://php.net/session.referer-check
 session.referer_check =
; how many bytes to read from the file.
 ; http://php.net/session.entropy-length
 session.entropy_length = 0
; specified here to create the session id.
 ; http://php.net/session.entropy-file
 ; on systems that don't have /dev/urandom /dev/arandom can be used
 ; on windows, setting the entropy_length setting will activate the
 ; windows random source (using the cryptoapi)
 ;session.entropy_file = /dev/urandom
; set to {nocache,private,public,} to determine http caching aspects
 ; or leave this empty to avoid sending anti-caching headers.
 ; http://php.net/session.cache-limiter
 session.cache_limiter = nocache
; document expires after n minutes.
 ; http://php.net/session.cache-expire
 session.cache_expire = 180
; trans sid support is disabled by default.
 ; use of trans sid may risk your users security.
 ; use this option with caution.
 ; - user may send url contains active session id
 ;   to other person via. email/irc/etc.
 ; - url that contains active session id may be stored
 ;   in publically accessible computer.
 ; - user may access your site with the same session id
 ;   always using url stored in browser's history or bookmarks.
 ; http://php.net/session.use-trans-sid
 session.use_trans_sid = 0
; select a hash function for use in generating session ids.
 ; possible values
 ;   0  (md5 128 bits)
 ;   1  (sha-1 160 bits)
 ; this option may also be set to the name of any hash function supported by
 ; the hash extension. a list of available hashes is returned by the hash_algos()
 ; function.
 ; http://php.net/session.hash-function
 session.hash_function = 0
; define how many bits are stored in each character when converting
 ; the binary hash data to something readable.
 ; possible values:
 ;   4  (4 bits: 0-9, a-f)
 ;   5  (5 bits: 0-9, a-v)
 ;   6  (6 bits: 0-9, a-z, a-z, "-", ",")
 ; default value: 4
 ; development value: 5
 ; production value: 5
 ; http://php.net/session.hash-bits-per-character
 session.hash_bits_per_character = 5
; the url rewriter will look for urls in a defined set of html tags.
 ; form/fieldset are special; if you include them here, the rewriter will
 ; add a hidden <input> field with the info which is otherwise appended
 ; to urls.  if you want xhtml conformity, remove the form entry.
 ; note that all valid entries require a "=", even if no value follows.
 ; default value: "a=href,area=href,frame=src,form=,fieldset="
 ; development value: "a=href,area=href,frame=src,input=src,form=fakeentry"
 ; production value: "a=href,area=href,frame=src,input=src,form=fakeentry"
 ; http://php.net/url-rewriter.tags
 url_rewriter.tags = "a=href,area=href,frame=src,input=src,form=fakeentry"

因为这个是在一台vps上面配置的，上面有多个项目，于是小编打开一个项目，发现此项目的验证码功能是ok的。
于是查看代码如下：

$sesssavepath = "/data/sessions/";
 // session保存路径
 if(is_writeable($sesssavepath) && is_readable($sesssavepath)){ session_save_path($sesssavepath); }
 if(!empty($cfg_domain_cookie)) session_set_cookie_params(0,'/',$cfg_domain_cookie);

上面这个代码是在session_start() 初始化之前来判断是否存在session会话的文件夹。
于是就在phpmyadmin里面的保存的那个文件/phpmyadmin/libraries/session.inc.php做了下修改:

if (! isset($_cookie[$session_name])) {
 // on first start of session we check for errors
 // f.e. session dir cannot be accessed - session file not created
 $orig_error_count = $globals['error_handler']->counterrors();
 //session_save_path('./tmp');
 session_save_path("/data/www/session");
 $r = session_start();
 if ($r !== true
 || $orig_error_count != $globals['error_handler']->counterrors()
 ) {
 setcookie($session_name, '', 1);
 /*
 * session initialization is done before selecting language, so we
 * can not use translations here.
 */
 pma_fatalerror('cannot start session without errors, please check errors given in your php and/or webserver log file and configure your php installation properly. also ensure that cookies are enabled in your browser.');
 }
 unset($orig_error_count);
 } else {
 session_save_path("/data/www/session");
 session_start();
 }

在 session_start();  前面添加了  session_save_path(“/data/www/session”); 就解决了这个问题。
切记通过@ini_set(‘session.save_path', ”/data/www/session”);无效！
这个问题困扰了我几个小时，终于解决了，所以就记录下来，对日后应该会有帮助。