Fix #79248: Traversing empty VT_ARRAY throws com_exception

If the `VT_ARRAY` is empty, i.e. its upperbound is less than its lower
bound, we must not call `php_com_safearray_get_elem()`, because that
function throws in this case.

Author: cmb69

NEWS

@@ -7,6 +7,7 @@ PHP                                                                        NEWS
     (cmb)
   . Fixed bug #79242 (COM error constants don't match com_exception codes on
     x86). (cmb)
+  . Fixed bug #79248 (Traversing empty VT_ARRAY throws com_exception). (cmb)
 
 - PCRE:
   . Fixed bug #79188 (Memory corruption in preg_replace/preg_replace_callback

ext/com_dotnet/com_iterator.c

@@ -187,7 +187,7 @@ zend_object_iterator *php_com_iter_get(zend_class_entry *ce, zval *object, int b
 		SafeArrayGetUBound(V_ARRAY(&I->safe_array), 1, &I->sa_max);
 
 		/* pre-fetch the element */
-		if (php_com_safearray_get_elem(&I->safe_array, &I->v, bound)) {
+		if (I->sa_max >= bound && php_com_safearray_get_elem(&I->safe_array, &I->v, bound)) {
 			I->key = bound;
 			ZVAL_NULL(&ptr);
 			php_com_zval_from_variant(&ptr, &I->v, I->code_page);

ext/com_dotnet/tests/bug79248.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Bug #79248 (Traversing empty VT_ARRAY throws com_exception)
+--SKIPIF--
+<?php
+if (!extension_loaded('com_dotnet')) die('skip com_dotnet extension not available');
+?>
+--FILE--
+<?php
+$v = new variant([], VT_ARRAY);
+foreach ($v as $el) {
+    var_dump($el);
+}
+echo "done\n";
+?>
+--EXPECT--
+done