Make var_export/debug_zval_dump first check for infinite recursion on the object

This test case previously failed with an assertion error in debug builds
(for updating an index of the array to set it to the same value it already had)

Then repeat the existing check on the return value of `get_properties_for`
in case there was a reason for doing it that way.

1. `HT_ASSERT_RC1(ht);` would fail for SplFixedArray and related
   datastructures.
2. In order for a native datastructure to correctly implement
   `*get_properties_for` for var_export's cycle detection,
   it would need to return the exact same array every time prior to this PR.

   This would prevent SplFixedArray or similar classes from returning a
   temporary array that:

   1. Wouldn't be affected by unexpected mutations from error handlers
   2. Could be garbage collected instead.

Note that SplFixedArray continues to need to return `object->properties`
until php 9.0, when dynamic properties are forbidden.

(GitHub wasn't updating the previous PR despite pushing the branch
to the right repo earlier, creating a new branch)

Closes GH-8044

Author: TysonAndre

ext/spl/tests/gh8044.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Bug GH-8044 (var_export/debug_zval_dump HT_ASSERT_RC1 debug failure for SplFixedArray)
+--FILE--
+<?php
+call_user_func(function () {
+    $x = new SplFixedArray(1);
+    $x[0] = $x;
+    var_export($x); echo "\n";
+    debug_zval_dump($x); echo "\n";
+});
+?>
+--EXPECTF--
+Warning: var_export does not handle circular references in %s on line 5
+SplFixedArray::__set_state(array(
+   0 => NULL,
+))
+object(SplFixedArray)#2 (1) refcount(4){
+  [0]=>
+  *RECURSION*
+}

ext/standard/var.c

@@ -343,11 +343,22 @@ PHPAPI void php_debug_zval_dump(zval *struc, int level) /* {{{ */
 		PUTS("}\n");
 		break;
 	case IS_OBJECT:
+		/* Check if this is already recursing on the object before calling zend_get_properties_for,
+		 * to allow infinite recursion detection to work even if classes return temporary arrays,
+		 * and to avoid the need to update the properties table in place to reflect the state
+		 * if the result won't be used. (https://github.com/php/php-src/issues/8044) */
+		if (Z_IS_RECURSIVE_P(struc)) {
+			PUTS("*RECURSION*\n");
+			return;
+		}
+		Z_PROTECT_RECURSION_P(struc);
+
 		myht = zend_get_properties_for(struc, ZEND_PROP_PURPOSE_DEBUG);
 		if (myht) {
 			if (GC_IS_RECURSIVE(myht)) {
 				PUTS("*RECURSION*\n");
 				zend_release_properties(myht);
+				Z_UNPROTECT_RECURSION_P(struc);
 				return;
 			}
 			GC_PROTECT_RECURSION(myht);
@@ -377,6 +388,7 @@ PHPAPI void php_debug_zval_dump(zval *struc, int level) /* {{{ */
 			php_printf("%*c", level - 1, ' ');
 		}
 		PUTS("}\n");
+		Z_UNPROTECT_RECURSION_P(struc);
 		break;
 	case IS_RESOURCE: {
 		const char *type_name = zend_rsrc_list_get_rsrc_type(Z_RES_P(struc));
@@ -552,9 +564,20 @@ PHPAPI void php_var_export_ex(zval *struc, int level, smart_str *buf) /* {{{ */
 			break;
 
 		case IS_OBJECT:
+			/* Check if this is already recursing on the object before calling zend_get_properties_for,
+			 * to allow infinite recursion detection to work even if classes return temporary arrays,
+			 * and to avoid the need to update the properties table in place to reflect the state
+			 * if the result won't be used. (https://github.com/php/php-src/issues/8044) */
+			if (Z_IS_RECURSIVE_P(struc)) {
+				smart_str_appendl(buf, "NULL", 4);
+				zend_error(E_WARNING, "var_export does not handle circular references");
+				return;
+			}
+			Z_PROTECT_RECURSION_P(struc);
 			myht = zend_get_properties_for(struc, ZEND_PROP_PURPOSE_VAR_EXPORT);
 			if (myht) {
 				if (GC_IS_RECURSIVE(myht)) {
+					Z_UNPROTECT_RECURSION_P(struc);
 					smart_str_appendl(buf, "NULL", 4);
 					zend_error(E_WARNING, "var_export does not handle circular references");
 					zend_release_properties(myht);
@@ -595,6 +618,7 @@ PHPAPI void php_var_export_ex(zval *struc, int level, smart_str *buf) /* {{{ */
 				GC_TRY_UNPROTECT_RECURSION(myht);
 				zend_release_properties(myht);
 			}
+			Z_UNPROTECT_RECURSION_P(struc);
 			if (level > 1 && !is_enum) {
 				buffer_append_spaces(buf, level - 1);
 			}