[libxml2] Fix regression with librsvg

[Nick Wellnhofer <nwellnhof src gnome org>]

commit b90d8989d3dc486519686f01490379c963bd1145
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Tue Sep 19 15:45:35 2017 +0200

    Fix regression with librsvg
    
    Instead of using xmlCreateIOParserCtxt, librsvg pushes its own
    xmlParserInput on top of a memory push parser. This incorrect use of
    the API confuses several parser checks and, since 2.9.5, completely
    breaks documents with internal subsets. Work around the problem with
    internal subsets.
    
    Thanks to Petr Sumbera for the report:
    
        https://mail.gnome.org/archives/xml/2017-September/msg00011.html
    
    Also see
    
        https://bugzilla.gnome.org/show_bug.cgi?id=787895

 parser.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/parser.c b/parser.c
index 770f846..28d0cd2 100644
--- a/parser.c
+++ b/parser.c
@@ -8271,6 +8271,7 @@ xmlParseInternalSubset(xmlParserCtxtPtr ctxt) {
      * Is there any DTD definition ?
      */
     if (RAW == '[') {
+        int baseInputNr = ctxt->inputNr;
         ctxt->instate = XML_PARSER_DTD;
         NEXT;
        /*
@@ -8278,7 +8279,7 @@ xmlParseInternalSubset(xmlParserCtxtPtr ctxt) {
         * PEReferences.
         * Subsequence (markupdecl | PEReference | S)*
         */
-       while (((RAW != ']') || (ctxt->inputNr > 1)) &&
+       while (((RAW != ']') || (ctxt->inputNr > baseInputNr)) &&
                (ctxt->instate != XML_PARSER_EOF)) {
            const xmlChar *check = CUR_PTR;
            unsigned int cons = ctxt->input->consumed;
@@ -8290,7 +8291,7 @@ xmlParseInternalSubset(xmlParserCtxtPtr ctxt) {
            if ((CUR_PTR == check) && (cons == ctxt->input->consumed)) {
                xmlFatalErr(ctxt, XML_ERR_INTERNAL_ERROR,
             "xmlParseInternalSubset: error detected in Markup declaration\n");
-                if (ctxt->inputNr > 1)
+                if (ctxt->inputNr > baseInputNr)
                     xmlPopInput(ctxt);
                 else
                    break;