[PHP] yet another session problem

[Richard Fox]

I am testing user-handling of sessions (mysql database) and just do not understand 
this behavior. my SESSION table is created as 

CREATE TABLE SESSION (
  id varchar(32) NOT NULL default '',
  time timestamp(14) NOT NULL,
  user_id mediumint(8) NOT NULL default '-1',
  data text NOT NULL,
  PRIMARY KEY  (id)
) TYPE=MyISAM;

I have a main script index.php3

<?php

require("./sessions.inc");

session_module_name("user");

session_set_save_handler("sess_open", "sess_close",
   "sess_read", "sess_write", "sess_remove", "sess_gc");

session_start();

if (!isset($_SESSION['zzzz']))  {
   $_SESSION['zzzz'] = 1;
   print("<br>zzzz set" );
   }


function increment() {
   $_SESSION['zzzz']++;
   echo "<br>zzzz=".$_SESSION['zzzz']."<br>";
   }

function set_yyyy() {
   echo "set yyyy<br>";
   $_SESSION['yyyy'] = 666;
   }


if (isset($_POST['MYVAR']))
   set_yyyy();
else
   increment();

echo "<a href=\"$PHP_SELF\">$PHP_SELF increment zzzz</A><br>";
echo "<a href=\"$PHP_SELF?MYVAR=3\">$PHP_SELF register yyyy</A>";

?>

and sessions.inc:

<?php

function session_table() {
   return("SESSION");
   }

function session_log($message) {
   if($file = fopen("/tmp/session.txt", "a")) {
      fwrite($file, date("Y-m-d H:i:s ") . $message . "\n");
      fclose($file);
      }
   }

function sess_open($path, $name) {
   session_log("session_open");
   return(true);
   }

function sess_close() {
   session_log("session_close");
   return(true);
   }

function sess_read($id) {
   session_log("session_read");
   $db = mysql_pconnect('localhost','mysqluser','password');
   if(!mysql_select_db('rfox_auth')) {
      session_log("session_read select database error: "
         . mysql_error());
      return("");
      }
   $sql = "select * from " . session_table()
      . " where id='" . $id . "'";
   if(!$result = mysql_query($sql)) {
      session_log("MySQL error: " . mysql_error()
         . " with SQL: " . $sql);
      return("");
      }
   if(mysql_num_rows($result)) {
      session_log("MySQL query returned " . mysql_num_rows($result)
         . " rows.");
      $row = mysql_fetch_assoc($result);
      session_log("session_read returned " . $row["data"]);
      return($row["data"]);
      }
   else {
      session_log("session_read found zero rows with SQL: " . $sql);
      return("");
      }
   }

function sess_write($id, $data) {
   session_log("session_write");
   if(!mysql_select_db('rfox_auth')) {
      session_log("session_write select database error: "
         . mysql_error());
      return(false);
      }
   $sql = "update " . session_table()
      . " set data = '" . addslashes($data) . "', time = null";
   $sql .= " where id='" . $id . "'";
   if (!$result = mysql_query($sql)) {
      session_log("session_write error " . mysql_error()
         . " with SQL: " . $sql);
      return(false);
      }
   if (mysql_affected_rows()) {
      session_log("session_write update affected "
         . mysql_affected_rows() . " rows with SQL: " . $sql);
      return(true);
      }
   session_log("session_write updated zero rows with SQL: " . $sql);
   $sql = "insert " . session_table()
      . " set data = '" . addslashes($data) . "', id = '" . $id . "'";
   if(!$result = mysql_query($sql)) {
      session_log("session_write error " . mysql_error()
         . " with SQL: " . $sql);
      return(false);
      }
   else {
      session_log("session_write inserted with SQL: " . $sql);
      return(true);
      }
   }


function sess_remove($id)
   {
   session_log("session_remove");
   if(!mysql_select_db('rfox_auth'))
      {
      session_log("session_remove select database error: "
         . mysql_error());
      return(false);
      }
   $sql = "delete " . session_table() . " where id='" . $id . "'";
   if ($result = mysql_query($sql))
      {
      session_log("MySQL query delete worked.");
      return(true);
      }
   else
      {
      session_log("MySQL update error: " . mysql_error()
         . " with SQL: " . $sql);
      return(false);
      }
   }

function sess_gc($life)
   {
   session_log("session_gc");
   if (!mysql_select_db('rfox_auth')) {
      session_log("session_gc select database error: " . mysql_error());
      return(false);
      }
   $sql = "delete from " . session_table() . " where time < '"
      . date("YmdHis", time() - $life) . "'";
   session_log("session_gc sql: " . $sql);
   if ($result = mysql_query($sql)) {
      session_log("session_gc deleted " . mysql_affected_rows()
         . " rows.");
      return(true);
      }
   else {
      session_log("session_gc error: " . mysql_error()
         . " with SQL: " . $sql);
      return(false);
      }
   }
?>

I can see in the log file that session_write() is executed when I register zzzz. But 
there is a problem:

PROBLEM: When I register yyyy, there is no call to session_write() in the log file, 
and no data for yyyy gets written to the database. 

Can you duplicate this behavior on your system? Do you have an explanation?

Thanks!

Rich