Example module source code for creating an PHP extension with hookable interface

hooker_bot_4000.c

zend_class_entry *hooker_bot_4000;

ZEND_BEGIN_ARG_INFO_EX(arginfo_void, 0, 0, 0)
ZEND_END_ARG_INFO()

const zend_function_entry hb4_functions[] = {
    PHP_ABSTRACT_ME(HookerBot4000, hookerBot4000, arginfo_void)
    PHP_FE_END
};

zend_module_entry hb4_module_entry = {
#if ZEND_MODULE_API_NO >= 20010901
    STANDARD_MODULE_HEADER,
#endif
    HB4_NAME,
    hooker_bot_functions,
    null,
    null,
    PHP_RINIT(hooker_bot_4000),
    NULL,
    NULL,
#if ZEND_MODULE_API_NO >= 20010901
    HB4_VERSION,
#endif
    STANDARD_MODULE_PROPERTIES
};

void * interface_implemented(zend_class_entry *ce TSRMLS_DC)
{
    php_printf("--------------interface_implemented----------------\n");
    return NULL;
}

void * never_called(zend_class_entry *ce TSRMLS_DC)
{
    php_printf("--------------never_called----------------\n");
    return NULL;
}

PHP_MINIT_FUNCTION(hello)
{
    zend_class_entry __tmpHB4;
	
    INIT_CLASS_ENTRY(tmp_interface, "HookerBot4000", hooker_bot_4000_functions);
    hooker_bot_4000 = zend_register_internal_interface(&__tmpHB4 TSRMLS_CC);
    
    // Actually called
    hooker_bot_4000->interface_gets_implemented = interface_implemented; // << Put Hooks here
    
    // Never called (should seg fault if called)
    hooker_bot_4000->constructor = never_called;
    hooker_bot_4000->create_object = never_called;
    hooker_bot_4000->__call = never_called;
    hooker_bot_4000->__get = never_called;
    hooker_bot_4000->__set = never_called;
    
    // For full list check-out https://github.com/php/php-src/blob/c9a538cdb441437181913c09bdc4425596e51f46/Zend/zend_API.h#L194
    
    return SUCCESS;
}