Make inspecting SplFixedArray instances more memory efficient/consistent, change print_r null props handling (#9757)

* Make handling of SplFixedArray properties more consistent

Create a brand new reference counted array every time in SplFixedArray
to be freed by the callers (or return null).
Switch from overriding `get_properties` to overriding `get_properties_for` handler

* Print objects with null hash table like others in print_r

Noticed when working on subsequent commits for SplFixedArray.
Make whether zend_get_properties_for returns null or an empty array
invisible to the end user - it would be always be a non-null array for
user-defined classes.
Always print newlines with `\n\s*(\n\s*)` after objects

Noticed when working on SplFixedArray changes, e.g. in
ext/spl/tests/SplFixedArray__construct_param_null.phpt

Zend/tests/function_arguments/sensitive_parameter_value.phpt

@@ -31,6 +31,8 @@ object(SensitiveParameterValue)#%d (0) {
 object(SensitiveParameterValue)#%d (%d) refcount(%d){
 }
 SensitiveParameterValue Object
+(
+)
 
 # var_export()
 \SensitiveParameterValue::__set_state(array(

Zend/zend.c

@@ -507,6 +507,7 @@ static void zend_print_zval_r_to_buf(smart_str *buf, zval *expr, int indent) /*
 				}
 
 				if ((properties = zend_get_properties_for(expr, ZEND_PROP_PURPOSE_DEBUG)) == NULL) {
+					print_hash(buf, (HashTable*) &zend_empty_array, indent, 1);
 					break;
 				}
 

ext/spl/spl_fixedarray.c

@@ -48,8 +48,6 @@ typedef struct _spl_fixedarray {
 	zend_long size;
 	/* It is possible to resize this, so this can't be combined with the object */
 	zval *elements;
-	/* True if this was modified after the last call to get_properties or the hash table wasn't rebuilt. */
-	bool                 should_rebuild_properties;
 } spl_fixedarray;
 
 typedef struct _spl_fixedarray_object {
@@ -107,7 +105,6 @@ static void spl_fixedarray_init_non_empty_struct(spl_fixedarray *array, zend_lon
 	array->size = 0; /* reset size in case ecalloc() fails */
 	array->elements = size ? safe_emalloc(size, sizeof(zval), 0) : NULL;
 	array->size = size;
-	array->should_rebuild_properties = true;
 }
 
 static void spl_fixedarray_init(spl_fixedarray *array, zend_long size)
@@ -177,7 +174,6 @@ static void spl_fixedarray_resize(spl_fixedarray *array, zend_long size)
 		/* nothing to do */
 		return;
 	}
-	array->should_rebuild_properties = true;
 
 	/* first initialization */
 	if (array->size == 0) {
@@ -211,47 +207,41 @@ static HashTable* spl_fixedarray_object_get_gc(zend_object *obj, zval **table, i
 	return ht;
 }
 
-static HashTable* spl_fixedarray_object_get_properties(zend_object *obj)
+static HashTable* spl_fixedarray_object_get_properties_for(zend_object *obj, zend_prop_purpose purpose)
 {
-	spl_fixedarray_object *intern = spl_fixed_array_from_obj(obj);
-	HashTable *ht = zend_std_get_properties(obj);
+	/* This has __serialize, so the purpose is not ZEND_PROP_PURPOSE_SERIALIZE, which would expect a non-null return value */
+	ZEND_ASSERT(purpose != ZEND_PROP_PURPOSE_SERIALIZE);
 
-	if (!spl_fixedarray_empty(&intern->array)) {
+	const spl_fixedarray_object *intern = spl_fixed_array_from_obj(obj);
 	/*
-		 * Usually, the reference count of the hash table is 1,
-		 * except during cyclic reference cycles.
-		 *
-		 * Maintain the DEBUG invariant that a hash table isn't modified during iteration,
-		 * and avoid unnecessary work rebuilding a hash table for unmodified properties.
-		 *
-		 * See https://github.com/php/php-src/issues/8079 and ext/spl/tests/fixedarray_022.phpt
-		 * Also see https://github.com/php/php-src/issues/8044 for alternate considered approaches.
+	 * SplFixedArray can be subclassed or have dynamic properties (With or without AllowDynamicProperties in subclasses).
+	 * Instances of subclasses with declared properties may have properties but not yet have a property table.
 	 */
-		if (!intern->array.should_rebuild_properties) {
-			/* Return the same hash table so that recursion cycle detection works in internal functions. */
-			return ht;
-		}
-		intern->array.should_rebuild_properties = false;
+	HashTable *source_properties = obj->properties ? obj->properties : (obj->ce->default_properties_count ? zend_std_get_properties(obj) : NULL);
 
-		zend_long j = zend_hash_num_elements(ht);
+	const zend_long size = intern->array.size;
+	if (size == 0 && (!source_properties || !zend_hash_num_elements(source_properties))) {
+		return NULL;
+	}
+	zval *const elements = intern->array.elements;
+	HashTable *ht = zend_new_array(size);
 
-		if (GC_REFCOUNT(ht) > 1) {
-			intern->std.properties = zend_array_dup(ht);
-			GC_TRY_DELREF(ht);
+	for (zend_long i = 0; i < size; i++) {
+		Z_TRY_ADDREF_P(&elements[i]);
+		zend_hash_next_index_insert(ht, &elements[i]);
 	}
-		for (zend_long i = 0; i < intern->array.size; i++) {
-			zend_hash_index_update(ht, i, &intern->array.elements[i]);
-			Z_TRY_ADDREF(intern->array.elements[i]);
-		}
-		if (j > intern->array.size) {
-			for (zend_long i = intern->array.size; i < j; ++i) {
-				zend_hash_index_del(ht, i);
-			}
-		}
-		if (HT_IS_PACKED(ht)) {
-			/* Engine doesn't expet packed array */
-			zend_hash_packed_to_hash(ht);
+	if (source_properties && zend_hash_num_elements(source_properties) > 0) {
+		zend_long nkey;
+		zend_string *skey;
+		zval *value;
+		ZEND_HASH_MAP_FOREACH_KEY_VAL_IND(source_properties, nkey, skey, value) {
+			Z_TRY_ADDREF_P(value);
+			if (skey) {
+				zend_hash_add_new(ht, skey, value);
+			} else {
+				zend_hash_index_update(ht, nkey, value);
 			}
+		} ZEND_HASH_FOREACH_END();
 	}
 
 	return ht;
@@ -394,9 +384,6 @@ static zval *spl_fixedarray_object_read_dimension(zend_object *object, zval *off
 	}
 
 	spl_fixedarray_object *intern = spl_fixed_array_from_obj(object);
-	if (type != BP_VAR_IS && type != BP_VAR_R) {
-		intern->array.should_rebuild_properties = true;
-	}
 	return spl_fixedarray_object_read_dimension_helper(intern, offset);
 }
 
@@ -420,7 +407,6 @@ static void spl_fixedarray_object_write_dimension_helper(spl_fixedarray_object *
 		zend_throw_exception(spl_ce_RuntimeException, "Index invalid or out of range", 0);
 		return;
 	} else {
-		intern->array.should_rebuild_properties = true;
 		/* Fix #81429 */
 		zval *ptr = &(intern->array.elements[index]);
 		zval tmp;
@@ -461,7 +447,6 @@ static void spl_fixedarray_object_unset_dimension_helper(spl_fixedarray_object *
 		zend_throw_exception(spl_ce_RuntimeException, "Index invalid or out of range", 0);
 		return;
 	} else {
-		intern->array.should_rebuild_properties = true;
 		zval_ptr_dtor(&(intern->array.elements[index]));
 		ZVAL_NULL(&intern->array.elements[index]);
 	}
@@ -973,7 +958,7 @@ PHP_MINIT_FUNCTION(spl_fixedarray)
 	spl_handler_SplFixedArray.unset_dimension = spl_fixedarray_object_unset_dimension;
 	spl_handler_SplFixedArray.has_dimension   = spl_fixedarray_object_has_dimension;
 	spl_handler_SplFixedArray.count_elements  = spl_fixedarray_object_count_elements;
-	spl_handler_SplFixedArray.get_properties  = spl_fixedarray_object_get_properties;
+	spl_handler_SplFixedArray.get_properties_for = spl_fixedarray_object_get_properties_for;
 	spl_handler_SplFixedArray.get_gc          = spl_fixedarray_object_get_gc;
 	spl_handler_SplFixedArray.free_obj        = spl_fixedarray_object_free_storage;
 

ext/spl/tests/ArrayObject_overloaded_SplFixedArray.phpt

@@ -0,0 +1,28 @@
+--TEST--
+SplFixedArray properties is compatible with ArrayObject
+--FILE--
+<?php
+$ao = new ArrayObject([1, 2, 3]);
+$fixedArray = new SplFixedArray(1);
+$fixedArray[0] = new SplDoublyLinkedList();
+$ao->exchangeArray($fixedArray);
+$ao[0] = new stdClass();
+var_dump($ao);
+?>
+--EXPECT--
+object(ArrayObject)#1 (1) {
+  ["storage":"ArrayObject":private]=>
+  object(SplFixedArray)#2 (2) {
+    [0]=>
+    object(SplDoublyLinkedList)#3 (2) {
+      ["flags":"SplDoublyLinkedList":private]=>
+      int(0)
+      ["dllist":"SplDoublyLinkedList":private]=>
+      array(0) {
+      }
+    }
+    ["0"]=>
+    object(stdClass)#4 (0) {
+    }
+  }
+}

ext/spl/tests/ArrayObject_overloaded_object_incompatible.phpt

@@ -5,7 +5,7 @@ Objects with overloaded get_properties are incompatible with ArrayObject
 
 $ao = new ArrayObject([1, 2, 3]);
 try {
-    $ao->exchangeArray(new SplFixedArray);
+    $ao->exchangeArray(new DateInterval('P1D'));
 } catch (Exception $e) {
     echo $e->getMessage(), "\n";
 }
@@ -13,7 +13,7 @@ var_dump($ao);
 
 ?>
 --EXPECT--
-Overloaded object of type SplFixedArray is not compatible with ArrayObject
+Overloaded object of type DateInterval is not compatible with ArrayObject
 object(ArrayObject)#1 (1) {
   ["storage":"ArrayObject":private]=>
   array(3) {

ext/spl/tests/SplFixedArray_get_properties_for.phpt

@@ -0,0 +1,86 @@
+--TEST--
+SplFixedArray - get_properties_for handlers
+--FILE--
+<?php
+#[AllowDynamicProperties]
+class MySplFixedArray extends SplFixedArray {
+    public $x;
+    public int $y;
+}
+class X {}
+class Y {}
+$array = new MySplFixedArray(2);
+var_dump(get_mangled_object_vars($array));
+$array[0] = new stdClass();
+$array[1] = new Y();
+$array->x = new SplFixedArray();
+$array->{0} = new X();
+var_dump($array);
+// As of php 8.3, get_mangled_object_vars only contains object properties (dynamic properties and declared subclass properties)
+//                (Array elements in the SplFixedArray are deliberately excluded)
+// Before php 8.3, this would have array elements get removed in some cases but not others.
+var_dump(get_mangled_object_vars($array));
+echo "cast to array\n";
+var_dump((array)$array); // Adds the values from the underlying array, then the declared/dynamic object properties
+echo json_encode($array), "\n"; // From JsonSerializable::serialize()
+$ser = serialize($array);
+echo "$ser\n";
+// NOTE: The unserialize behavior for the property that is the string '0' is just because unserialize()
+// is coercing '0' to a string before calling SplFixedArray::__unserialize.
+//
+// Typical code would not use 0 as a property name, this test is just testing edge cases have proper reference counting and so on.
+var_dump(unserialize($ser));
+?>
+--EXPECT--
+array(1) {
+  ["x"]=>
+  NULL
+}
+object(MySplFixedArray)#1 (4) {
+  [0]=>
+  object(stdClass)#2 (0) {
+  }
+  [1]=>
+  object(Y)#3 (0) {
+  }
+  ["x"]=>
+  object(SplFixedArray)#4 (0) {
+  }
+  ["0"]=>
+  object(X)#5 (0) {
+  }
+}
+array(2) {
+  ["x"]=>
+  object(SplFixedArray)#4 (0) {
+  }
+  [0]=>
+  object(X)#5 (0) {
+  }
+}
+cast to array
+array(3) {
+  [0]=>
+  object(X)#5 (0) {
+  }
+  [1]=>
+  object(Y)#3 (0) {
+  }
+  ["x"]=>
+  object(SplFixedArray)#4 (0) {
+  }
+}
+[{},{}]
+O:15:"MySplFixedArray":5:{i:0;O:8:"stdClass":0:{}i:1;O:1:"Y":0:{}s:1:"x";i:0;s:1:"y";i:0;s:1:"0";O:1:"X":0:{}}
+object(MySplFixedArray)#6 (4) {
+  [0]=>
+  object(X)#9 (0) {
+  }
+  [1]=>
+  object(Y)#8 (0) {
+  }
+  ["x"]=>
+  int(0)
+  ["y"]=>
+  int(0)
+}

ext/spl/tests/SplFixedArray_immediate_gc.phpt

@@ -0,0 +1,35 @@
+--TEST--
+SplFixedArray - values should be gced after var_export then being modified
+--FILE--
+<?php
+class HasDestructor {
+    public function __destruct() {
+        echo "In destructor\n";
+    }
+}
+$array = SplFixedArray::fromArray([new HasDestructor()]);
+var_dump($array);
+echo "Replacing\n";
+$array[0] = new stdClass();
+// As of php 8.3, this will be freed before the var_dump call
+echo "Dumping again\n";
+var_dump($array);
+// As of php 8.3, this only contain object properties (dynamic properties and declared subclass properties)
+var_dump(get_mangled_object_vars($array));
+?>
+--EXPECT--
+object(SplFixedArray)#2 (1) {
+  [0]=>
+  object(HasDestructor)#1 (0) {
+  }
+}
+Replacing
+In destructor
+Dumping again
+object(SplFixedArray)#2 (1) {
+  [0]=>
+  object(stdClass)#3 (0) {
+  }
+}
+array(0) {
+}

ext/spl/tests/SplFixedArray_setSize_destruct.phpt

@@ -12,6 +12,7 @@ class HasDestructor {
         global $values;
         var_dump($values);
         $values->setSize($values->getSize() - 1);
+        echo "After reducing size:\n";
         var_dump($values);
     }
 }
@@ -24,9 +25,8 @@ object(SplFixedArray)#1 (1) {
   [0]=>
   bool(false)
 }
-object(SplFixedArray)#1 (1) {
-  [0]=>
-  bool(false)
+After reducing size:
+object(SplFixedArray)#1 (0) {
 }
 Done
 Done
@@ -43,6 +43,7 @@ object(SplFixedArray)#1 (5) {
   object(HasDestructor)#2 (0) {
   }
 }
+After reducing size:
 object(SplFixedArray)#1 (4) {
   [0]=>
   NULL