session_module_name
This may sound no-brainer: the session_name() function will have no essential effect if you set session.auto_start to "true" in php.ini . And the obvious explanation is the session already started thus cannot be altered before the session_name() function--wherever it is in the script--is executed, same reason session_name needs to be called before session_start() as documented.
I know it is really not a big deal. But I had a quite hard time before figuring this out, and hope it might be helpful to someone like me.
session_name
(PHP 4, PHP 5)
session_name — 現在のセッション名を取得または設定する
説明
string session_name
([ string
$name
] )
session_name() は、現在のセッション名を返します。
name を渡すと、
session_name() はセッション名を上書きして元のセッション名を返します。
リクエストが開始された際にセッション名はリセットされ、 session.name に保存されたデフォルト値に戻ります。 よって、各リクエスト毎に(そして session_start() または session_register() をコールする前に) session_name() をコールする必要があります。
パラメータ
-
name -
セッションの名前を参照します。これは、クッキーや URL (例: PHPSESSID) で使われます。 セッション名は英数字のみで構成されている必要があり、また、 短く、その内容が分かるようなものである必要があります (これは、クッキー警告を有効にしているユーザー用です)。
警告セッション名は数字だけで構成することはできません。 少なくとも文字がひとつ以上現れる必要があります。そうでない場合、 新規セッション ID が毎回生成されます。
返り値
現在のセッションの名前を返します。
例
例1 session_name() の例
<?php
/* セッション名をWebsiteIDに設定する */
$previous_name = session_name("WebsiteID");
echo "前回のセッション名は、$previous_name です。<br />";
?>
add a note
User Contributed Notes
session_name - [6 notes]
Hongliang Qiang ¶
8 years ago
Joseph Dalrymple ¶
2 years ago
For those wondering, this function is expensive!
On a script that was executing in a consistent 0.0025 seconds, just the use of session_name("foo") shot my execution time up to ~0.09s. By simply sacrificing session_name("foo"), I sped my script up by roughly 0.09 seconds.
relsqui at chiliahedron dot com ¶
4 years ago
Remember, kids--you MUST use session_name() first if you want to use session_set_cookie_params() to, say, change the session timeout. Otherwise it won't work, won't give any error, and nothing in the documentation (that I've seen, anyway) will explain why.
Thanks to brandan of bildungsroman.com who left a note under session_set_cookie_params() explaining this or I'd probably still be throwing my hands up about it.
php at wiz dot cx ¶
4 years ago
if you try to name a php session "example.com" it gets converted to "example_com" and everything breaks.
don't use a period in your session name.
slave at codegrunt dot com ¶
8 years ago
One gotcha I have noticed with session_name is that it will trigger a WARNING level error if the cookie or GET/POST variable value has something other than alphanumeric characters in it. If your site displays warnings and uses PHP sessions this may be a way to enumerate at least some of your scripts:
http://example.com/foo.php?session_name_here=(bad)
Warning: session_start(): The session id contains invalid characters, valid characters are only a-z, A-Z and 0-9 in /some/path/foo.php on line 666
I did not see anything in the docs suggesting that one had to sanitize the PHP session ID values before opening the session but that appears to be the case.
Unfortunately session_name() always returns true so you have to actually get to the point of assigning variables values before you know whether you have been passed bad session data (as far as I can see). After the error has been generated in other words.
Cheers
webmaster at nncoders dot de ¶
4 years ago
You can always just use "or".
@foo or bar();
When foo fails, (and the at still means don't print an error to the browser), the function bar will be executed.
<?php
function errorhandler () { /* do something wild */ }
@session_name('mysession') or errorhandler();
?>
Another live example would be
@mysql_query('show databases') or die(mysql_error());
When the execution fails, parameter die is called (with last mysql_error as given string parameter)