[libxml2] Don't process siblings of root in xmlXIncludeProcess

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 11b5745927481d6a716acef5408da20899eab8a2
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Fri Aug 7 18:39:19 2020 +0200

    Don't process siblings of root in xmlXIncludeProcess
    
    xmlXIncludeDoProcess would follow the siblings of the tree root and
    also expand these nodes. When using an XML reader, this could lead to
    siblings of the current node being expanded without having been parsed
    completely.

 xinclude.c | 38 ++++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 20 deletions(-)
---
diff --git a/xinclude.c b/xinclude.c
index 0f1af9c3d..2917d4565 100644
--- a/xinclude.c
+++ b/xinclude.c
@@ -1980,6 +1980,8 @@ xmlXIncludeLoadFallback(xmlXIncludeCtxtPtr ctxt, xmlNodePtr fallback, int nr) {
         (ctxt == NULL))
        return(-1);
     if (fallback->children != NULL) {
+        xmlNodePtr child, next;
+
        /*
         * It's possible that the fallback also has 'includes'
         * (Bug 129969), so we re-process the fallback just in case
@@ -1990,11 +1992,13 @@ xmlXIncludeLoadFallback(xmlXIncludeCtxtPtr ctxt, xmlNodePtr fallback, int nr) {
        newctxt->_private = ctxt->_private;
        newctxt->base = xmlStrdup(ctxt->base);  /* Inherit the base from the existing context */
        xmlXIncludeSetFlags(newctxt, ctxt->parseFlags);
-       ret = xmlXIncludeDoProcess(newctxt, ctxt->doc, fallback->children);
+        for (child = fallback->children; child != NULL; child = next) {
+            next = child->next;
+           if (xmlXIncludeDoProcess(newctxt, ctxt->doc, child) < 0)
+                ret = -1;
+        }
        if (ctxt->nbErrors > oldNbErrors)
            ret = -1;
-       else if (ret > 0)
-           ret = 0;    /* xmlXIncludeDoProcess can return +ve number */
        xmlXIncludeFreeContext(newctxt);
 
        ctxt->incTab[nr]->inc = xmlDocCopyNodeList(ctxt->doc,
@@ -2396,7 +2400,7 @@ xmlXIncludeDoProcess(xmlXIncludeCtxtPtr ctxt, xmlDocPtr doc, xmlNodePtr tree) {
      * First phase: lookup the elements in the document
      */
     cur = tree;
-    while ((cur != NULL) && (cur != tree->parent)) {
+    do {
        /* TODO: need to work on entities -> stack */
         if (xmlXIncludeTestNode(ctxt, cur) == 1) {
             xmlXIncludePreProcessNode(ctxt, cur);
@@ -2407,22 +2411,16 @@ xmlXIncludeDoProcess(xmlXIncludeCtxtPtr ctxt, xmlDocPtr doc, xmlNodePtr tree) {
             cur = cur->children;
             continue;
         }
-       if (cur->next != NULL) {
-           cur = cur->next;
-       } else {
-           if (cur == tree)
-               break;
-           do {
-               cur = cur->parent;
-               if ((cur == NULL) || (cur == tree->parent))
-                   break; /* do */
-               if (cur->next != NULL) {
-                   cur = cur->next;
-                   break; /* do */
-               }
-           } while (cur != NULL);
-       }
-    }
+        do {
+            if (cur == tree)
+                break;
+            if (cur->next != NULL) {
+                cur = cur->next;
+                break;
+            }
+            cur = cur->parent;
+        } while (cur != NULL);
+    } while ((cur != NULL) && (cur != tree));
 
     /*
      * Second Phase : collect the infosets fragments