Avoid crash for reset/end/next/prev() on ffi classes (#9711)

(And any PECLs returning `zend_empty_array` in the handler->get_properties
overrides)

Closes GH-9697

This is similar to the fix used in d9651a9
for array_walk.

This should make it safer for php-src (and PECLs, long-term) to return
the empty immutable array in `handler->get_properties` to avoid wasting memory.
See #9697 (comment)

The only possible internal iterator position for the empty array is at the end
of the empty array (nInternalPointer=0).
The `zend_hash*del*` helpers will always set nInternalPointer to 0 when an
array becomes empty,
regardless of previous insertions/deletions/updates to the array.

Author: TysonAndre

NEWS

@@ -27,6 +27,8 @@ PHP                                                                        NEWS
   . Fixed bug GH-10292 (Made the default value of the first param of srand() and
     mt_srand() unknown). (kocsismate)
   . Fix incorrect check in cs_8559_5 in map_from_unicode(). (nielsdos)
+  . Fix bug GH-9697 for reset/end/next/prev() attempting to move pointer of
+    properties table for certain internal classes such as FFI classes
 
 02 Feb 2023, PHP 8.1.15
 

ext/ffi/tests/arrayPointer.phpt

@@ -0,0 +1,20 @@
+--TEST--
+FFI: Test deprecated use of array helper functions on FFI classes doesn't crash
+--EXTENSIONS--
+ffi
+--INI--
+ffi.enable=1
+--FILE--
+<?php
+error_reporting(E_ALL & ~E_DEPRECATED);
+$data = FFI::new('int');
+var_dump(reset($data));
+var_dump(end($data));
+var_dump(next($data));
+var_dump(prev($data));
+?>
+--EXPECTF--
+bool(false)
+bool(false)
+bool(false)
+bool(false)

ext/standard/array.c

@@ -1073,6 +1073,10 @@ PHP_FUNCTION(end)
 	ZEND_PARSE_PARAMETERS_END();
 
 	HashTable *array = get_ht_for_iap(array_zv, /* separate */ true);
+	if (zend_hash_num_elements(array) == 0) {
+		/* array->nInternalPointer is already 0 if the array is empty, even after removing elements */
+		RETURN_FALSE;
+	}
 	zend_hash_internal_pointer_end(array);
 
 	if (USED_RET()) {
@@ -1100,6 +1104,10 @@ PHP_FUNCTION(prev)
 	ZEND_PARSE_PARAMETERS_END();
 
 	HashTable *array = get_ht_for_iap(array_zv, /* separate */ true);
+	if (zend_hash_num_elements(array) == 0) {
+		/* array->nInternalPointer is already 0 if the array is empty, even after removing elements */
+		RETURN_FALSE;
+	}
 	zend_hash_move_backwards(array);
 
 	if (USED_RET()) {
@@ -1127,6 +1135,10 @@ PHP_FUNCTION(next)
 	ZEND_PARSE_PARAMETERS_END();
 
 	HashTable *array = get_ht_for_iap(array_zv, /* separate */ true);
+	if (zend_hash_num_elements(array) == 0) {
+		/* array->nInternalPointer is already 0 if the array is empty, even after removing elements */
+		RETURN_FALSE;
+	}
 	zend_hash_move_forward(array);
 
 	if (USED_RET()) {
@@ -1154,6 +1166,10 @@ PHP_FUNCTION(reset)
 	ZEND_PARSE_PARAMETERS_END();
 
 	HashTable *array = get_ht_for_iap(array_zv, /* separate */ true);
+	if (zend_hash_num_elements(array) == 0) {
+		/* array->nInternalPointer is already 0 if the array is empty, even after removing elements */
+		RETURN_FALSE;
+	}
 	zend_hash_internal_pointer_reset(array);
 
 	if (USED_RET()) {