Count number of filters already on the stream

Instead of counting iterations on the loop

Related to:
php#10453
php#16699

Author: Sjoerd Langkemper

ext/standard/php_fopen_wrapper.c

@@ -164,13 +164,21 @@ static void php_stream_apply_filter_list(php_stream *stream, char *filterlist, i
 		php_url_decode(p, strlen(p));
 		if (read_chain) {
 			if ((temp_filter = php_stream_filter_create(p, NULL, php_stream_is_persistent(stream)))) {
+				if (php_stream_filter_count(&stream->readfilters) > max_stream_filters) {
+					zend_throw_exception_ex(NULL, 0, "Unable to apply read filter, maximum number (%d) reached", max_stream_filters);
+					return;
+				}
 				php_stream_filter_append(&stream->readfilters, temp_filter);
 			} else {
 				php_error_docref(NULL, E_WARNING, "Unable to create filter (%s)", p);
 			}
 		}
 		if (write_chain) {
 			if ((temp_filter = php_stream_filter_create(p, NULL, php_stream_is_persistent(stream)))) {
+				if (php_stream_filter_count(&stream->writefilters) > max_stream_filters) {
+					zend_throw_exception_ex(NULL, 0, "Unable to apply write filter, maximum number (%d) reached", max_stream_filters);
+					return;
+				}
 				php_stream_filter_append(&stream->writefilters, temp_filter);
 			} else {
 				php_error_docref(NULL, E_WARNING, "Unable to create filter (%s)", p);

main/streams/filter.c

@@ -447,6 +447,20 @@ PHPAPI void _php_stream_filter_append(php_stream_filter_chain *chain, php_stream
 	}
 }
 
+PHPAPI int php_stream_filter_count(php_stream_filter_chain *chain) {
+    if (chain->head == NULL) {
+        return 0;
+    }
+
+    int count = 1;
+    php_stream_filter *node = chain->head;
+    while (node != chain->tail) {
+        count += 1;
+        node = node->next;
+    }
+    return count;
+}
+
 PHPAPI zend_result _php_stream_filter_flush(php_stream_filter *filter, bool finish)
 {
 	php_stream_bucket_brigade brig_a = { NULL, NULL }, brig_b = { NULL, NULL }, *inp = &brig_a, *outp = &brig_b, *brig_temp;

main/streams/php_stream_filter_api.h

@@ -138,6 +138,7 @@ PHPAPI void _php_stream_filter_prepend(php_stream_filter_chain *chain, php_strea
 PHPAPI void php_stream_filter_prepend_ex(php_stream_filter_chain *chain, php_stream_filter *filter);
 PHPAPI void _php_stream_filter_append(php_stream_filter_chain *chain, php_stream_filter *filter);
 PHPAPI zend_result php_stream_filter_append_ex(php_stream_filter_chain *chain, php_stream_filter *filter);
+PHPAPI int php_stream_filter_count(php_stream_filter_chain *chain);
 PHPAPI zend_result _php_stream_filter_flush(php_stream_filter *filter, bool finish);
 PHPAPI php_stream_filter *php_stream_filter_remove(php_stream_filter *filter, bool call_dtor);
 PHPAPI void php_stream_filter_free(php_stream_filter *filter);