php die() running twice?

Question

How is it possible that the snippet below prints out "readablenot readable" ? afaik a die() should stop everything immediately?

EDIT: posted the full function. This is a function from Zend_Search_Lucene_Storage_File_Filesystem. We're always getting "file not readable" errors. The file does seem to be readable but the snippet below prints out "readablenot readable"

EDIT 2: sorry, made some mistakes in the info I posted; all correct now.

public function __construct($filename, $mode='r+b')
    {
        global $php_errormsg;

        if(strpos($mode, 'w') === false) {
            die('not readable');
        }
        else die('readable');

        if (strpos($mode, 'w') === false  &&  !is_readable($filename)) {
            // opening for reading non-readable file
            require_once 'Zend/Search/Lucene/Exception.php';
            throw new Zend_Search_Lucene_Exception('File \'' . $filename . '\' is not readable.');
        }

        $trackErrors = ini_get('track_errors');
        ini_set('track_errors', '1');

        $this->_fileHandle = @fopen($filename, $mode);

        if ($this->_fileHandle === false) {
            ini_set('track_errors', $trackErrors);
            require_once 'Zend/Search/Lucene/Exception.php';
            throw new Zend_Search_Lucene_Exception($php_errormsg);
        }

        ini_set('track_errors', $trackErrors);
    }

Answer 1

I'm gonna go out on a limb and say:

It's not possible.

Unless: You're echoing 'ok' someplace else before the die() or it's in a destructor/shutdown function.

From the manual on exit() which is the same as die():

Terminates execution of the script. Shutdown functions and object destructors will always be executed even if exit() is called.

But the code posted, by itself, would never result in an output of 'okok'.

To Troubleshoot:

• Change the echoed line to something more traceable. Include the file name (__file__) and line number (__line__) just to make sure it really is the same line being executed.
• Add a debugger (something like xdebug) to give you a stack trace. Is the function somehow being called twice (by a destructor or shutdown hook)?

Answer 2

die() triggers execution of shutdown hooks, so the second call may be part of a code path belonging to a shotdown hook.

Answer 3

One answer could be that you have something in your script which caused the offending code to run twice (i.e. a non-terminated http redirect, or your class is being instantiated twice).

Track back from the point (or points) where your class is instantiated and look for possible duplication. Or, setup a unit test / script that does nothing else but instantiate the class once with the minimal amount of data required for the test.