PHPC-282: Cursor should not yield multiple iterators

Successive get_iterator handler invocations should throw a LogicException. This avoids situations that might allow the user to iterate over the same cursor multiple times.

Author: jmikola

php_phongo.c

@@ -1696,18 +1696,26 @@ zend_object_iterator_funcs php_phongo_cursor_iterator_funcs = {
 
 zend_object_iterator *php_phongo_cursor_get_iterator(zend_class_entry *ce, zval *object, int by_ref TSRMLS_DC) /* {{{ */
 {
+	php_phongo_cursor_t *cursor = zend_object_store_get_object(object TSRMLS_CC);
 	php_phongo_cursor_iterator *cursor_it = NULL;
 
 	if (by_ref) {
 		zend_error(E_ERROR, "An iterator cannot be used with foreach by reference");
 	}
 
+	if (cursor->got_iterator) {
+		phongo_throw_exception(PHONGO_ERROR_LOGIC TSRMLS_CC, "Cursors cannot yield multiple iterators");
+		return NULL;
+	}
+
+	cursor->got_iterator = 1;
+
 	cursor_it = ecalloc(1, sizeof(php_phongo_cursor_iterator));
 
 	Z_ADDREF_P(object);
 	cursor_it->intern.data  = (void*)object;
 	cursor_it->intern.funcs = &php_phongo_cursor_iterator_funcs;
-	cursor_it->cursor = (php_phongo_cursor_t *)zend_object_store_get_object(object TSRMLS_CC);
+	cursor_it->cursor = cursor;
 	/* cursor_it->current should already be allocated to zero */
 
 	php_phongo_cursor_free_current(cursor_it->cursor);

php_phongo_classes.h

@@ -40,6 +40,7 @@ typedef struct {
 	mongoc_client_t         *client;
 	int                      server_id;
 	php_phongo_bson_state    visitor_data;
+	int                      got_iterator;
 } php_phongo_cursor_t;
 
 typedef struct {

tests/standalone/cursor-get_iterator-001.phpt

@@ -0,0 +1,60 @@
+--TEST--
+MongoDB\Driver\Cursor get_iterator handler does not yield multiple iterators (foreach)
+--SKIPIF--
+<?php require __DIR__ . "/../utils/basic-skipif.inc"; CLEANUP(STANDALONE) ?>
+--FILE--
+<?php
+require_once __DIR__ . "/../utils/basic.inc";
+
+$manager = new MongoDB\Driver\Manager(STANDALONE);
+
+$bulkWrite = new MongoDB\Driver\BulkWrite;
+
+for ($i = 0; $i < 3; $i++) {
+    $bulkWrite->insert(array('_id' => $i));
+}
+
+$writeResult = $manager->executeBulkWrite(NS, $bulkWrite);
+printf("Inserted: %d\n", $writeResult->getInsertedCount());
+
+$cursor = $manager->executeQuery(NS, new MongoDB\Driver\Query(array()));
+
+echo "\nFirst foreach statement:\n";
+
+foreach ($cursor as $document) {
+    var_dump($document);
+}
+
+echo "\nSecond foreach statement:\n";
+
+try {
+    foreach ($cursor as $document) {
+        echo "FAILED: get_iterator should not yield multiple iterators\n";
+    }
+} catch (MongoDB\Driver\Exception\LogicException $e) {
+    printf("LogicException: %s\n", $e->getMessage());
+}
+
+?>
+===DONE===
+<?php exit(0); ?>
+--EXPECT--
+Inserted: 3
+
+First foreach statement:
+array(1) {
+  ["_id"]=>
+  int(0)
+}
+array(1) {
+  ["_id"]=>
+  int(1)
+}
+array(1) {
+  ["_id"]=>
+  int(2)
+}
+
+Second foreach statement:
+LogicException: Cursors cannot yield multiple iterators
+===DONE===

tests/standalone/cursor-get_iterator-002.phpt

@@ -0,0 +1,46 @@
+--TEST--
+MongoDB\Driver\Cursor get_iterator handler does not yield multiple iterators (IteratorIterator)
+--SKIPIF--
+<?php require __DIR__ . "/../utils/basic-skipif.inc"; CLEANUP(STANDALONE) ?>
+--FILE--
+<?php
+require_once __DIR__ . "/../utils/basic.inc";
+
+$manager = new MongoDB\Driver\Manager(STANDALONE);
+
+$bulkWrite = new MongoDB\Driver\BulkWrite;
+
+for ($i = 0; $i < 3; $i++) {
+    $bulkWrite->insert(array('_id' => $i));
+}
+
+$writeResult = $manager->executeBulkWrite(NS, $bulkWrite);
+printf("Inserted: %d\n", $writeResult->getInsertedCount());
+
+$cursor = $manager->executeQuery(NS, new MongoDB\Driver\Query(array()));
+
+echo "\nFirst IteratorIterator wrapping:\n";
+
+var_dump(new IteratorIterator($cursor));
+
+echo "\nSecond IteratorIterator wrapping:\n";
+
+try {
+    var_dump(new IteratorIterator($cursor));
+} catch (MongoDB\Driver\Exception\LogicException $e) {
+    printf("LogicException: %s\n", $e->getMessage());
+}
+
+?>
+===DONE===
+<?php exit(0); ?>
+--EXPECTF--
+Inserted: 3
+
+First IteratorIterator wrapping:
+object(IteratorIterator)#%d (0) {
+}
+
+Second IteratorIterator wrapping:
+LogicException: Cursors cannot yield multiple iterators
+===DONE===