From 71a7a33e18fce3822405be2c4ce40d03064d48ea Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Fri, 3 May 2024 00:44:42 +0200
Subject: [PATCH] parser: Fix base URI of internal parameter entities

Search parent inputs of internal parameter entities for base URI.

Fixes a long-standing bug, which manifested in a different way after
commit 955c177f. Reproduce with

    xmllint --noent xmlconf/eduni/errata-2e/E18.xml
---
 SAX2.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/SAX2.c b/SAX2.c
index a347023b..b8011fec 100644
--- a/SAX2.c
+++ b/SAX2.c
@@ -559,9 +559,14 @@ xmlSAX2EntityDecl(void *ctx, const xmlChar *name, int type,
     if ((ent->URI == NULL) && (systemId != NULL)) {
         xmlChar *URI;
         const char *base = NULL;
+        int i;
 
-        if (ctxt->input != NULL)
-            base = ctxt->input->filename;
+        for (i = ctxt->inputNr - 1; i >= 0; i--) {
+            if (ctxt->inputTab[i]->filename != NULL) {
+                base = ctxt->inputTab[i]->filename;
+                break;
+            }
+        }
 
         if (xmlBuildURISafe(systemId, (const xmlChar *) base, &URI) < 0) {
             xmlSAX2ErrMemory(ctxt);