[Resolved] Identical class methods - one produces segfault!

[ppowell]

Consider these two classes. Class Accepter in placement_classes.inc.php works as a form validation object, and it works like a charm:

// placement_classes.inc.php - THIS ONE WORKS!

class Accepter {

  function Accepter() {
 		$this->dbAP =& new DBActionPerformer();
		$this->dbAP->connect();
		$this->validate();
		$this->dbAP->disconnect();
		$this->dbAP = null;
  }

/**
 * Perform validation
 *
 * @access private
 */
function &validate() {																		// STATIC VOID METHOD
	foreach ($_POST as $key => $val) if (!isset(${$key})) ${$key} = $val;
	$varErrArray = array();
	array_push($varErrArray, 'placement_name|setMandatory~setMinLength~setMaxLength~setPattern|You must enter a location name~Your location name must be 2 or more characters~Your location name must be 50 or fewer characters in length~^(?!.*<[^>]+>)|Your location name configuration is unrecognizable by our system, please re-enter with legitimate characters|');
	array_push($varErrArray, 'unique_key|setMandatory|You must have a unique key prior to posting||');

	/*---------------------------------------------------------------------------------------------------------------------
	  createErrorMsgCollection function from formvalidation.inc standalone function returns an array of ErrorMsgCollection 
	  objects
	-----------------------------------------------------------------------------------------------------------------------*/
	$this->errorMsgObjArray =& createErrorMsgCollection($varErrArray);

	// CREATE FORM OBJECT PASSING ARRAY OF OBJECTS AS PARAMETER
	$this->formValidator =& new FormValidator('', $this->errorMsgObjArray);
	$this->isValid = $this->formValidator->isValid();
	$this->setErrorArray($this->formValidator->getErrorArray());
	$this->formValidator = null;
	$this->errorMsgObjArray = null;

            /*
	if (strcmp(strtolower($action), 'add') == 0 || (strcmp(strtolower($action), 'edit') == 0 && $placement_name !== $origPlacementName))
	 $this->checkDuplicatePlacement($placement_name);		// CHECK FOR DUPLICATE PLACEMENT
            */
}

}

This is the class Accepter from contacts_classes.inc.php and while it is now identical in code structure to the Accepter classe in placement_classes.inc.php, whenever this class method is invoked, all processes stop (no errors), arrays are unfinished, objects are unfinished, HTTP never produces, Apache goes down, literally everything crashes!

// contacts_classes.inc.php - THIS ONE PRODUCES A POSSIBLE SEG FAULT!

class Accepter {

function Accepter() {
	// NEW 8/17/2004: SURROUND validate() METHOD WITH INSTANTIATION OF $this->dbAP OBJECT PROPERTY
	$this->dbAP =& new DBActionPerformer();
	$this->dbAP->connect();
	$this->validate();
	$this->dbAP->disconnect();
	$this->dbAP = null;
}

/**
 * Main method.  Will perform all other validation methods and set isValid boolean property
 *
 * @access public
 */
function &validate() {									// STATIC VOID METHOD
	foreach ($_POST as $key => $val) if (!isset(${$key})) ${$key} = $val;
	$varErrArray = array();
	array_push($varErrArray, 'placement_name|setMandatory~setMinLength~setMaxLength~setPattern|You must enter a location name~Your location name must be 2 or more characters~Your location name must be 50 or fewer characters in length~^(?!.*<[^>]+>)|Your location name configuration is unrecognizable by our system, please re-enter with legitimate characters|');
	array_push($varErrArray, 'unique_key|setMandatory|You must have a unique key prior to posting||');

	/*---------------------------------------------------------------------------------------------------------------------
	  createErrorMsgCollection function from formvalidation.inc standalone function returns an array of ErrorMsgCollection 
	  objects
	-----------------------------------------------------------------------------------------------------------------------*/
	$this->errorMsgObjArray =& createErrorMsgCollection($varErrArray);

	// CREATE FORM OBJECT PASSING ARRAY OF OBJECTS AS PARAMETER
	$this->formValidator =& new FormValidator('', $this->errorMsgObjArray);
	$this->isValid = $this->formValidator->isValid();
	$this->setErrorArray($this->formValidator->getErrorArray());
	$this->formValidator = null;
	$this->errorMsgObjArray = null;

	/*
	if (strcmp(strtolower($action), 'delete_select') == 0 && @sizeof($delete_selected) == 0) {
	 $this->isValid = false;
	 $this->setErrorArray(array('action' => 'You must select at least one contact for deletion'));
	}
	*/
}

}

I've been trying to debug this for days now to no avail. I can verify every object property is present and accounted for (and identical in every way), but if you evoke one it's fine, the other and a segfault!

Help!

Thanx
Phil

[ahundiak]

Couple of gueses:

1. It does not appear that validate returns a value. So the & in function &validate is not needed.

2. You have a comment : // STATIC VOID METHOD
   Are you in fact calling validate statically somewhere? Static methods cannot use $this.

3. Are you using ERROR_REPORTING(E_ALL)? If not then it might give you a hint.

4. Are these cut down versions of validate? I don't see why you are basically exploding $_POST or where the exploded values are being used. You are aware that created variables are local in scope and cannot be accessed outside of the method?

5. And how does the form validator know the form is valid? Does it explode $POST as well? How does it know which form is being processed?

[ppowell]

This is a hunch but I think this might be the culprit:

foreach ($_POST as $key => $val) if (!isset(${$key})) ${$key} = $val;

Basically, foreach looping moves the array internal pointer and doesn't put it back, thus, there is a possibility that $_POST was being referenced within one of the FormValidator methods with the misplaced array pointer.

I am not able to test this but your comments are definitely noted. I am putting '&' in front of 'validate' in order to call it "statically", or the closest that PHP version 4 can get to calling a single instance of $this->validate() in memory (to prevent memory stack overflow of all objects during application iteration and execution). I am using error_reporting(E_ALL & ~E_NOTICE); and have normally seen all errors except for this one, which I think is not a PHP error at all but a segfault. And yes, I am deliberately creating local variables based upon $_POST for manipulation purposes within the class method.

$this->validate() will not know it's valid until you instantiate a FormValidator object and run its isValid() method by, again, parsing through $POST to determine if the correctly formed values, if necessary, exist within $POST.

That's why the only thing I can think of is the "time bomb" idea: that by not resetting $_POST after iteration using foreach() resulting in a matter-of-time segfault.

Phil

[ahundiak]

Foreach does reset the internal counter. It's easy to show this. You only run into problems when using nested foreach's on the same array.

I'd suggest using error_reporting(E_ALL);
Instead of suppressing the notices. Got too many notices? I'd suggest refactoring your code to get rid of them. Notices are very helpful in finding misspelt variable names and other obscure errors.

Putting & in front of a method name has nothing to do with calling it statically. The & says to return a reference to your return value instead of a copy. If the method does not return anything then the & is useless.

If you only want one instance of the Acceptor class then only create one instance. And remember, it makes no sense to use $this in a "static" method. By definition, a static method can have no instance data.

I am kind of guessing that you have & sprinkled through your code in an inappropiate manner. And that some strange combination is causing the seg fault.

Are you calling Acceptor->validate multiple times? Are you expecting that the local variables generated from $POST will persist between each call? Hence the isset? Be aware that local variables are recreated each time validate is called. Maybe you want to explode $POST in the constructor and create instance data for each element.

[ppowell]

Foreach does reset the internal counter. It's easy to show this. You only run into problems when using nested foreach's on the same array.

And that wasn't the problem after all. Still producing segfaults 🙁

I'd suggest using error_reporting(E_ALL);
Instead of suppressing the notices. Got too many notices? I'd suggest refactoring your code to get rid of them. Notices are very helpful in finding misspelt variable names and other obscure errors.

I am getting not just too many notices, but the weirdest thing I've ever seen in PHP: I'm getting an infinite loop of the same two notices on a class method that I'm not even referencing at all! It turns out that I am trying to use FormValidator::isValid() method but it's references JavascriptGeneator::isValid() method instead, and there is nothing anywhere in this application I'm writing that even USES that class nor method (another unrelated application does but it's completely separate and unrelated to this application)

Putting & in front of a method name has nothing to do with calling it statically. The & says to return a reference to your return value instead of a copy. If the method does not return anything then the & is useless.

If you only want one instance of the Acceptor class then only create one instance. And remember, it makes no sense to use $this in a "static" method. By definition, a static method can have no instance data.

Perhaps I can explain what I'm trying to do. Picture a Java static void method. Only one instance in memory of a void method. That's what I'm trying to do in PHP.

I am kind of guessing that you have & sprinkled through your code in an inappropiate manner. And that some strange combination is causing the seg fault.

Are you calling Acceptor->validate multiple times? Are you expecting that the local variables generated from $POST will persist between each call? Hence the isset? Be aware that local variables are recreated each time validate is called. Maybe you want to explode $POST in the constructor and create instance data for each element.

Accepter->validate() is called once and once only. It seems to, however be calling JavascriptGenerator->isValid() method an infinite amount of times, causing a memory leak and thus possibly a segfault.

Phil

[ahundiak]

Glad to see that you are making progress. Sounds like you might have an infinite recursion going on somewhere. And something is accidently including the JavaScript library.

Have you a link to any documentation relating & to static? Thats a new one on me. Are you familiar with the php static keyword? I think it's closer to what you want though if validate is only being called once then I still don't see the point.

In any event, good luck.

[ppowell]

I found where it occurs and I can't explain this one, this sounds like a possible PHP bug. The script "validation_script.inc.php" is required once via require_once(); it calls an Accepter class object instance once; the Accepter class object instance invokes the validate() method only once, and this line is the offending line, that is, again, called only once:

$this->isValid = $this->formValidator->isValid();

If I comment that line out everything works just fine, if I do not, then somehow calling that method causes a referencing to another class in another script that's not even called:

classes.inc.php
JavascriptGenerator
isValidJS()

I checked the code in FormValidator (in formvalidation.inc.php) and at no time is it even referencing classes.inc.php, much less the JavascriptGenerator class.

Yet, for some cracked reason, one class method infinitely instantiates an unrelated (and inaccessible) class method elsewhere.

This has GOT to be a PHP bug!

Phil

[ahundiak]

It could be a PHP bug but seems unlikely. Any chance of posting the complete code on a web site (with .phps extensions). I'll bet the problem is obvious to another pair of eyes.

[ppowell]

Thanx.. turns out it was more buried than I could possibly imagine. Suffice to say that one unrelated class method was instantiating its own grandchild that evokes it's own grandparent. Thus, infinite loop.

Phil