From afad37216b7aaf6c4faf60cce7358a7bbc04c2b1 Mon Sep 17 00:00:00 2001
From: Mike Dalessio <mike.dalessio@gmail.com>
Date: Sun, 31 Jan 2021 09:53:56 -0500
Subject: [PATCH] parser.c: shrink the input buffer when appropriate

Fixes GNOME/libxml2#200

Also see discussions at:
- GNOME/libxml2#192
- https://gitlab.gnome.org/nwellnhof/libxml2/-/commit/99bda1e
- https://github.com/sparklemotion/nokogiri/issues/2132
---
 parser.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/parser.c b/parser.c
index a7bdc7f3d..efde672fb 100644
--- a/parser.c
+++ b/parser.c
@@ -4204,6 +4204,7 @@ xmlParseSystemLiteral(xmlParserCtxtPtr ctxt) {
 	}
 	count++;
 	if (count > 50) {
+	    SHRINK;
 	    GROW;
 	    count = 0;
             if (ctxt->instate == XML_PARSER_EOF) {
@@ -4291,6 +4292,7 @@ xmlParsePubidLiteral(xmlParserCtxtPtr ctxt) {
 	buf[len++] = cur;
 	count++;
 	if (count > 50) {
+	    SHRINK;
 	    GROW;
 	    count = 0;
             if (ctxt->instate == XML_PARSER_EOF) {
@@ -4571,6 +4573,7 @@ xmlParseCharDataComplex(xmlParserCtxtPtr ctxt, int cdata) {
 	}
 	count++;
 	if (count > 50) {
+	    SHRINK;
 	    GROW;
 	    count = 0;
             if (ctxt->instate == XML_PARSER_EOF)
@@ -4776,6 +4779,7 @@ xmlParseCommentComplex(xmlParserCtxtPtr ctxt, xmlChar *buf,
 
 	count++;
 	if (count > 50) {
+	    SHRINK;
 	    GROW;
 	    count = 0;
             if (ctxt->instate == XML_PARSER_EOF) {
@@ -5186,6 +5190,7 @@ xmlParsePI(xmlParserCtxtPtr ctxt) {
 		}
 		count++;
 		if (count > 50) {
+		    SHRINK;
 		    GROW;
                     if (ctxt->instate == XML_PARSER_EOF) {
                         xmlFree(buf);
@@ -9783,6 +9788,7 @@ xmlParseCDSect(xmlParserCtxtPtr ctxt) {
 	sl = l;
 	count++;
 	if (count > 50) {
+	    SHRINK;
 	    GROW;
             if (ctxt->instate == XML_PARSER_EOF) {
 		xmlFree(buf);