Description:
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It appears this bug exists regardless of any version of php or OS or web server. I have physically tested this to occur across:
- Windows 7, Windows Server 2012 R2
- PHP Version 5.3, 5.4, 5.5, 5.6 and 7.0.10 (all binaries downloaded from php.net windows already compiled as NTS x86 and x64)
- Apache 2.2 and IIS (7+8)

My php.ini has been modified only for session.save_handler = user. All other settings left as default.

What happens is that if I submit a form with file upload progress utilisation (ie. name as value from ini_get("session.upload_progress.name")) then the upload actually crashes the script and my error log file contains the contents :

PHP Warning:  Unknown: user session functions not defined in Unknown on line 0
PHP Fatal error:  Unknown: Failed to initialize storage module: user (path: C:\WINDOWS\Temp) in Unknown on line 0

It appears that php is trying to default back to use save_hander=files and then fails. If i COMMENT OUT the PHP_SESSION_UPLOAD_PROGRESS line so that file upload progress is disabled, it works perfectly. It also works perfectly if i set the save_handler back to "files" in my php.ini.

Naturally, even if it didnt generate a fatal error, the file session info would still be inaccessible to my database session if it succeeds in writing to the file.

 

Test script:
---------------
The html form looks like this :

<iframe id="upload_iframe" name="upload_iframe" style="width: 1px; height: 1px; display: block;border:0px;"></iframe>
<form id="myUploadForm" name="myUploadForm" target="upload_iframe" action="uploadFile.php" method="post" enctype="multipart/form-data">
<input type="hidden" name="UID" value="1">
<input type="hidden" value="myUploadForm" name="PHP_SESSION_UPLOAD_PROGRESS">
<input type="file" class="upload" name="file" id="file">
<input type="submit" class="cmi-button small white" value="Upload" onclick="fileUpload.startUploadMonitoring();">
</form>

My session_set_save_handler override for _open looks like this :

function _open() {
    if( ($this->dbc = mysqli_connect(DBSettings::HOSTNAME, DBSettings::USERNAME, DBSettings::PASSWORD)) !== false ) {
      $select_db = mysqli_select_db($this->dbc, DBSettings::DATABASE_SHARED_SERVICES);
      // $set_charset = mysqli_set_charset($this->dbc, DB_CHARSET);
      return( $select_db /*&& $set_charset*/ );
    }
    else {
      trigger_error(mysqli_error($this->dbc), E_USER_ERROR);
    }

    return( false );
  }

(but i think the above handler override is irrelevant to this bug as even if i change the trigger_error to return true rather, it makes no difference as the error occurs BEFORE control is handed over to the USER script)



Expected result:
----------------
it should firstly NOT crash PHP, and secondly it should use the php.ini setting for my database session handler.

my error log file contains the contents :

PHP Warning:  Unknown: user session functions not defined in Unknown on line 0
PHP Fatal error:  Unknown: Failed to initialize storage module: user (path: C:\WINDOWS\Temp) in Unknown on line 0

Actual result:
--------------
my error log file contains the contents :

PHP Warning:  Unknown: user session functions not defined in Unknown on line 0
PHP Fatal error:  Unknown: Failed to initialize storage module: user (path: C:\WINDOWS\Temp) in Unknown on line 0