Live migrate the PHP session to database

Migrate the PHP session from disk to database live. To pull this off, the
session contents are written to database under the current session id. When
the `ostversion` column is dropped from the %config table, the system will
automatically switch to database-backed sessions in osTicket 1.7 mode.

This is sort-of hacked together by carefully calling a instance method of
the osTicketSession class statically, and modify the instance method to
support static invocation.

include/class.ostsession.php

@@ -67,10 +67,13 @@ class osTicketSession {
     function write($id, $data){
         global $thisstaff;
 
+        $ttl = ($this && get_class($this) == 'osTicketSession') 
+            ? $this->getTTL() : SESSION_TTL;
+
         $sql='REPLACE INTO '.SESSION_TABLE.' SET session_updated=NOW() '.
              ',session_id='.db_input($id).
              ',session_data='.db_input($data).
-             ',session_expire=(NOW() + INTERVAL '.$this->getTTL().' SECOND)'.
+             ',session_expire=(NOW() + INTERVAL '.$ttl.' SECOND)'.
              ',user_id='.db_input($thisstaff?$thisstaff->getId():0).
              ',user_ip='.db_input($_SERVER['REMOTE_ADDR']).
              ',user_agent='.db_input($_SERVER['HTTP_USER_AGENT']);

include/class.upgrader.php

@@ -181,9 +181,11 @@ class Upgrader extends SetupWizard {
 
     function doTasks() {
 
+        global $ost;
         if(!($tasks=$this->getPendingTasks()))
             return true; //Nothing to do.
 
+        $ost->logDebug('Upgrader', sprintf('There are %d pending upgrade tasks', count($tasks)));
         $start_time = Misc::micro_time();
         foreach($tasks as $k => $task) {
             //TODO: check time used vs. max execution - break if need be
@@ -238,6 +240,9 @@ class Upgrader extends SetupWizard {
             $shash = substr($phash, 9, 8);
             $_SESSION['ost_upgrader'][$shash]['tasks'] = $tasks;
             $_SESSION['ost_upgrader'][$shash]['state'] = 'upgrade';
+            
+            $ost->logDebug('Upgrader', sprintf('Found %d tasks to be executed for %s',
+                            count($tasks), $shash));
             break;
 
         }
@@ -253,13 +258,16 @@ class Upgrader extends SetupWizard {
             case 'c00511c7-7be60a84': //V1.6 ST- 1.7 * {{MD5('1.6 ST') -> c00511c7c1db65c0cfad04b4842afc57}}
                 $tasks[] = array('func' => 'migrateAttachments2DB',
                                  'desc' => 'Migrating attachments to database, it might take a while depending on the number of files.');
+                $tasks[] = array('func' => 'migrateSessionFile2DB',
+                                 'desc' => 'Transitioning to db-backed sessions');
                 break;
         }
 
         //Check IF SQL cleanup is exists. 
         $file=$this->getSQLDir().$phash.'.cleanup.sql';
         if(file_exists($file)) 
-            $tasks[] = array('func' => 'cleanup', 'desc' => 'Post-upgrade cleanup!');
+            $tasks[] = array('func' => 'cleanup', 'desc' => 'Post-upgrade cleanup!',
+                        'phash' => $phash);
 
 
         return $tasks;
@@ -267,8 +275,11 @@ class Upgrader extends SetupWizard {
 
     /************* TASKS **********************/
     function cleanup($taskId) {
+        global $ost;
+
+        $phash = $this->tasks[$taskId]['phash'];
+        $file=$this->getSQLDir().$phash.'.cleanup.sql';
 
-        $file=$this->getSQLDir().$this->getShash().'-cleanup.sql';
         if(!file_exists($file)) //No cleanup script.
             return 0;
 
@@ -276,11 +287,13 @@ class Upgrader extends SetupWizard {
         if($this->load_sql_file($file, $this->getTablePrefix(), false, true))
             return 0;
 
-        //XXX: ???
-        return false;
+        $ost->logDebug('Upgrader', sprintf("%s: Unable to process cleanup file",
+                        $phash));
+        return 0;
     }
 
     function migrateAttachments2DB($taskId) {
+        global $ost;
         
         if(!($max_time = ini_get('max_execution_time')))
             $max_time = 30; //Default to 30 sec batches.
@@ -291,5 +304,11 @@ class Upgrader extends SetupWizard {
 
         return $att_migrater->getQueueLength();
     }
+
+    function migrateSessionFile2DB($taskId) {
+        # How about 'dis for a hack?
+        osTicketSession::write(session_id(), session_encode()); 
+        return 0;
+    }
 }
 ?>

scp/logout.php

@@ -21,7 +21,6 @@ $ost->logDebug('Staff logout',
 $_SESSION['_staff']=array();
 session_unset();
 session_destroy();
-session_write_close();
 @header('Location: login.php');
 require('login.php');
 ?>

scp/upgrade.php

@@ -27,9 +27,10 @@ if($_POST && $_POST['s'] && !$upgrader->isAborted()) {
                 $errors['err']=' Nothing to do! System already upgraded to the current version';
             elseif(!$upgrader->isUpgradable())
                 $errors['err']='The upgrader does NOT support upgrading from the current vesion!';
-            elseif($upgrader->check_prereq())
+            elseif($upgrader->check_prereq()) {
                 $upgrader->setState('upgrade');
-            else
+                $_SESSION['ost_upgrader'] = null;
+            } else
                 $errors['prereq']='Minimum requirements not met!';
             break;
         case 'upgrade': //Manual upgrade.... when JS (ajax) is not supported.