定制php4的session功能

;

if ($expires_at > time()) {
$var = substr($tmp, strpos($tmp, "|") + 1);
}
}

return $var;
}

function sess_write($key, $val) {
global $SESS_DBM, $SESS_LIFE;

dbmreplace($SESS_DBM, $key, time() + $SESS_LIFE . "|" . $val);
return true;
}

function sess_destroy($key) {
global $SESS_DBM;

dbmdelete($SESS_DBM, $key);
return true;
}

function sess_gc($maxlifetime) {
global $SESS_DBM;

$now = time();
$key = dbmfirstkey($SESS_DBM);
while ($key) {
if ($tmp = dbmfetch($SESS_DBM, $key)) {
$expires_at = substr($tmp, 0, strpos($tmp, "|"));
if ($now > $expires_at) {
sess_destroy($key);
}
}

$key = dbmnextkey($SESS_DBM, $key);
}
}

session_set_save_handler(
"sess_open",
"sess_close",
"sess_read",
"sess_write",
"sess_destroy",
"sess_gc");
?>
=====================================================================================
session_mysql.php
=======================================================================================
<?
/* ------------------------------------------------------------------------
* session_mysql.php
* ------------------------------------------------------------------------
* PHP4 MySQL Session Handler
* Version 1.00
* by Ying Zhang (ying@zippydesign.com)
* Last Modified: May 21 2000
*
* ------------------------------------------------------------------------
* TERMS OF USAGE:
* ------------------------------------------------------------------------
* You are free to use this library in any way you want, no warranties are
* expressed or implied. This works for me, but I don''t guarantee that it
* works for you, USE AT YOUR OWN RISK.
*
* While not required to do so, I would appreciate it if you would retain
* this header information. If you make any modifications or improvements,
* please send them via email to Ying Zhang <ying@zippydesign.com>.
*
* ------------------------------------------------------------------------
* DESCRIPTION:
* ------------------------------------------------------------------------
* This library tells the PHP4 session handler to write to a MySQL database
* instead of creating individual files for each session.
*
* Create a new database in MySQL called "sessions" like so:
*
* CREATE TABLE sessions (
* sesskey char(32) not null,
* expiry int(11) unsigned not null,
* value text not null,
* PRIMARY KEY (sesskey)
* );
*
* ------------------------------------------------------------------------
* INSTALLATION:
* ------------------------------------------------------------------------
* Make sure you have MySQL support compiled into PHP4. Then copy this
* script to a directory that is accessible by the rest of your PHP
* scripts.
*
* ------------------------------------------------------------------------
* USAGE:
* ------------------------------------------------------------------------
* Include this file in your scripts before you call session_start(), you
* don''t have to do anything special after tha