need help with PHP's codebase in C - determining which properties are 'dynamic'

[sneakyimp]

I've been working on and off for some time on a PHP extension (like PECL) which will serialize/unserialize PHP data structures to/from AMF3 format. Thanks to some help from Bradgrafelman, I've got the encoding functions all done except when it comes to serializing an object. I've tested my code and so far its serialization output is identical to that of Flash Player, which makes me proud. Also, it is fast -- about 20-200 times faster than equivalent serialization functions written in PHP.

I'm hoping now to finally implement serializing of objects. For these, AMF3 defines a few distinct scenarios that have different results:
i) This exact object has been encountered and serialized before so we just serialize a reference id that refers to the previously serialized object. I've got this taken care of.
ii) U29O-traits-ref : we have serialized an instance of this class before so we don't need to specify all the trait/property names all over again, we can just serialize the instance values and simply pass a reference for the trait/property names and sequence.
iii) U29O-traits-ext : the object to be serialized implements interface iExternalizable which handles serialization in PHP space. In this case my C code would need to invoke some function in PHP code space.
iv) U29O-traits : Used for both stdClass/generic object and classes that are not iExternalizable. There are two variants: a) object is an 'orthodox' instance of its class (i.e., no extra dynamic properties) or b) Object has dynamically assigned properties beyond those specified by its class.

So in the interest of finishing my encoding functions, I need to be able to accomplish a few things in my C code:
1) Determine if a particular object implements the iExternalizable interface. Since no such interface exists as part of native PHP, this will probably require me to implement code in my extension that defines a class in PHP space and somehow check an incoming object against that interface.
2) Possibly evoke a function defined in PHP space on a particular object and return the results to C space.
3) Determine if a particular object has only 'orthodox' properties or whether someone has dynamically assigned additional ones. Obviously, any stdClass objects are dynamic. This would provide an example of a custom class with dynamic properties:

class foo {
	public $orthodox1 = 'orth1';
	public $orthodox2 = 'orth2';
}
$v = new foo();
$v->dynamic = "I am a dynamic trait";
var_dump($v);

I've seen C code that, given an object, val, will use the C macros and/or functions to extract some representation of its type:

  zend_class_entry *ce = Z_TYPE_P(val) == IS_OBJECT ? Z_OBJCE_P(val) : zend_standard_class_def;

And I've been looking at php_var_serialize_intern and php_var_serialize_class to try and am slowly understanding things, but I'm confused by concepts like an "incomplete class". For example, how does the return value incomplete_class get defined in php_var_serialize_class_name?

Perhaps most confusing at the moment for me is determining which properties are orthodox ones and which are dynamically allocated.

Any help would be much appreciated.

[sneakyimp]

So I think I will be able to make progress on generic objects. I set up an Actionscript file that serializes a single generic Object with a single property and POSTs it to a PHP script that writes it to a file:

var obj:Object = new Object();
obj["A"] = "a";

// byte array to store AMF3-encoded object
var bytes: ByteArray = new ByteArray();
bytes.writeObject(obj3);

//– set up correct url request using post in binary mode
var request:URLRequest = new URLRequest
("http://localhost/flashmog/test");
var loader: URLLoader = new URLLoader();
request.contentType = "application/octet-stream";
request.method = URLRequestMethod.POST;
request.data = bytes;
loader.load( request );

My PHP on the other end writes this data to a file:

$var = file_get_contents('php://input');
file_put_contents('/tmp/flash_testing.txt', $var);

In this case, the result:

$ xxd /tmp/flash_testing.txt
0000000: 0a0b 0103 4106 0361 01                   ....A..a.

This data represents Adobe's own serialization of the object.

I'm still having trouble figuring out how to take an object with 'orthodox' properties (i.e., this defined by its class) and dynamically assigned ones. I've been looking at the C code underyling the [man]get_class_vars[/man] function which can be found here. This function appears to get the 'default properties' of the class by first using zend_lookup_class to locate a zend_class_entry object describing the class and then passing this along to an add_class_vars function. This seems similar to what I will need to do but I'm pretty confused about how to move forward or what the best strategies might be for looping through properties most effectively. The PHP source just doesn't have any comments at all so it's hard to understand what functions & macros do.