Implement a POC for spl_object_id(object $x) : int

https://github.com/runkit7/runkit_object_id is a C module which
implements the same functionality (Without obfuscation)

Pending question: Can `sizeof(zend_long)` be > `sizeof(intptr_t)`

- If so, detect that condition at compile time and return a binary string
  with that many bytes, instead.

Also, can two PHP "object"s have the same object id,
but different object handlers? (E.g. iterator of a class)

- If that is so, then document if this case is possible, but keep behaving the same way.

Author: TysonAndre

ext/spl/php_spl.c

@@ -794,14 +794,32 @@ PHP_FUNCTION(spl_object_hash)
 }
 /* }}} */
 
+/* {{{ proto int spl_object_id(object obj)
+ Return integer hash id for given object */
+PHP_FUNCTION(spl_object_id)
+{
+	zval *obj;
+
+	ZEND_PARSE_PARAMETERS_START(1, 1)
+		Z_PARAM_OBJECT(obj)
+	ZEND_PARSE_PARAMETERS_END_EX(RETURN_NULL());
+
+	RETURN_LONG(php_spl_object_id(obj));
+}
+/* }}} */
+
+static void php_spl_init_hash_mask() {
+	SPL_G(hash_mask_handle)   = (intptr_t)(php_mt_rand() >> 1);
+	SPL_G(hash_mask_handlers) = (intptr_t)(php_mt_rand() >> 1);
+	SPL_G(hash_mask_init) = 1;
+}
+
 PHPAPI zend_string *php_spl_object_hash(zval *obj) /* {{{*/
 {
 	intptr_t hash_handle, hash_handlers;
 
 	if (!SPL_G(hash_mask_init)) {
-		SPL_G(hash_mask_handle)   = (intptr_t)(php_mt_rand() >> 1);
-		SPL_G(hash_mask_handlers) = (intptr_t)(php_mt_rand() >> 1);
-		SPL_G(hash_mask_init) = 1;
+		php_spl_init_hash_mask();
 	}
 
 	hash_handle   = SPL_G(hash_mask_handle)^(intptr_t)Z_OBJ_HANDLE_P(obj);
@@ -811,6 +829,20 @@ PHPAPI zend_string *php_spl_object_hash(zval *obj) /* {{{*/
 }
 /* }}} */
 
+PHPAPI zend_long php_spl_object_id(zval *obj) /* {{{*/
+{
+	intptr_t hash_handle;
+
+	if (!SPL_G(hash_mask_init)) {
+		php_spl_init_hash_mask();
+	}
+
+	hash_handle   = SPL_G(hash_mask_handle)^(intptr_t)Z_OBJ_HANDLE_P(obj);
+
+	return (zend_long) hash_handle;
+}
+/* }}} */
+
 int spl_build_class_list_string(zval *entry, char **list) /* {{{ */
 {
 	char *res;
@@ -915,6 +947,10 @@ ZEND_END_ARG_INFO()
 ZEND_BEGIN_ARG_INFO_EX(arginfo_spl_object_hash, 0, 0, 1)
 	ZEND_ARG_INFO(0, obj)
 ZEND_END_ARG_INFO()
+
+ZEND_BEGIN_ARG_INFO_EX(arginfo_spl_object_id, 0, 0, 1)
+	ZEND_ARG_INFO(0, obj)
+ZEND_END_ARG_INFO()
 /* }}} */
 
 /* {{{ spl_functions
@@ -931,6 +967,7 @@ const zend_function_entry spl_functions[] = {
 	PHP_FE(class_implements,        arginfo_class_implements)
 	PHP_FE(class_uses,              arginfo_class_uses)
 	PHP_FE(spl_object_hash,         arginfo_spl_object_hash)
+	PHP_FE(spl_object_id,           arginfo_spl_object_id)
 #ifdef SPL_ITERATORS_H
 	PHP_FE(iterator_to_array,       arginfo_iterator_to_array)
 	PHP_FE(iterator_count,          arginfo_iterator)

ext/spl/php_spl.h

@@ -71,6 +71,7 @@ PHP_FUNCTION(class_implements);
 PHP_FUNCTION(class_uses);
 
 PHPAPI zend_string *php_spl_object_hash(zval *obj);
+PHPAPI zend_long php_spl_object_id(zval *obj);
 
 #endif /* PHP_SPL_H */