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Subject: Re: intercepting function calls
From: pollita@php.net ("Sara Golemon")

> Is it possible to intercept a function call (user
> space or built-in) in the Zend Engine and execute user
> space code before/after the function call?
>
Yes, you can do this by way of a Zend extension (not a PHP extension mind 
you).

The parts of Zend/zend_extensions.h you'll want to pay attention to are:

typedef void (*fcall_begin_handler_func_t)(zend_op_array *op_array);
typedef void (*fcall_end_handler_func_t)(zend_op_array *op_array);

struct _zend_extension {
    ...
    fcall_begin_handler_func_t fcall_begin_handler;
    fcall_end_handler_func_t fcall_end_handler;
    ...
};

-Sara