From 16b0dbc1b3d1b8bdf0340b60119f36e6b45fd7a7 Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Fri, 29 Dec 2023 18:47:30 +0100
Subject: [PATCH] parser: Fix XML_ERR_UNSUPPORTED_ENCODING errors

Commit 45157261 added the check in the wrong place.

Also allow unsupported encoding in xmlNewInputInternal.

Fixes #654.
---
 error.c           |  3 +++
 parserInternals.c | 30 +++++++++++++++---------------
 testparser.c      | 29 +++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/error.c b/error.c
index 4f71c036..a68451e4 100644
--- a/error.c
+++ b/error.c
@@ -1161,6 +1161,9 @@ xmlErrString(xmlParserErrors code) {
         case XML_ERR_REDECL_PREDEF_ENTITY:
             errmsg = "Invalid redeclaration of predefined entity";
             break;
+        case XML_ERR_UNSUPPORTED_ENCODING:
+            errmsg = "Unsupported encoding";
+            break;
 
         case XML_IO_UNKNOWN:
             errmsg = "Unknown IO error"; break;
diff --git a/parserInternals.c b/parserInternals.c
index 8a15fdaa..4e0920d9 100644
--- a/parserInternals.c
+++ b/parserInternals.c
@@ -175,11 +175,9 @@ xmlCtxtErrIO(xmlParserCtxtPtr ctxt, int code, const char *uri)
     if (ctxt == NULL)
         return;
 
-    if (code == XML_ERR_UNSUPPORTED_ENCODING) {
-        level = XML_ERR_WARNING;
-    } else if ((code == XML_IO_ENOENT) ||
-               (code == XML_IO_NETWORK_ATTEMPT) ||
-               (code == XML_IO_UNKNOWN)) {
+    if ((code == XML_IO_ENOENT) ||
+        (code == XML_IO_NETWORK_ATTEMPT) ||
+        (code == XML_IO_UNKNOWN)) {
         if (ctxt->validate == 0)
             level = XML_ERR_WARNING;
         else
@@ -318,17 +316,23 @@ xmlCtxtErr(xmlParserCtxtPtr ctxt, xmlNodePtr node, xmlErrorDomain domain,
  * Handle a fatal parser error, i.e. violating Well-Formedness constraints
  */
 void
-xmlFatalErr(xmlParserCtxtPtr ctxt, xmlParserErrors error, const char *info)
+xmlFatalErr(xmlParserCtxtPtr ctxt, xmlParserErrors code, const char *info)
 {
     const char *errmsg;
+    xmlErrorLevel level;
 
-    errmsg = xmlErrString(error);
+    if (code == XML_ERR_UNSUPPORTED_ENCODING)
+        level = XML_ERR_WARNING;
+    else
+        level = XML_ERR_FATAL;
+
+    errmsg = xmlErrString(code);
 
     if (info == NULL) {
-        xmlCtxtErr(ctxt, NULL, XML_FROM_PARSER, error, XML_ERR_FATAL,
+        xmlCtxtErr(ctxt, NULL, XML_FROM_PARSER, code, level,
                    NULL, NULL, NULL, 0, "%s\n", errmsg);
     } else {
-        xmlCtxtErr(ctxt, NULL, XML_FROM_PARSER, error, XML_ERR_FATAL,
+        xmlCtxtErr(ctxt, NULL, XML_FROM_PARSER, code, level,
                    (const xmlChar *) info, NULL, NULL, 0,
                    "%s: %s\n", errmsg, info);
     }
@@ -1560,12 +1564,8 @@ xmlNewInputInternal(xmlParserCtxtPtr ctxt, xmlParserInputBufferPtr buf,
         }
     }
 
-    if (encoding != NULL) {
-        if (xmlSwitchInputEncodingName(ctxt, input, encoding) < 0) {
-            xmlFreeInputStream(input);
-            return(NULL);
-        }
-    }
+    if (encoding != NULL)
+        xmlSwitchInputEncodingName(ctxt, input, encoding);
 
     return(input);
 }
diff --git a/testparser.c b/testparser.c
index 287f08b6..35cd27b5 100644
--- a/testparser.c
+++ b/testparser.c
@@ -9,6 +9,34 @@
 
 #include <string.h>
 
+static int
+testUnsupportedEncoding(void) {
+    xmlDocPtr doc;
+    const xmlError *error;
+    int err = 0;
+
+    xmlResetLastError();
+
+    doc = xmlReadDoc(BAD_CAST "<doc/>", NULL, "#unsupported",
+                     XML_PARSE_NOWARNING);
+    if (doc == NULL) {
+        fprintf(stderr, "xmlReadDoc failed with unsupported encoding\n");
+        err = 1;
+    }
+    xmlFreeDoc(doc);
+
+    error = xmlGetLastError();
+    if (error->code != XML_ERR_UNSUPPORTED_ENCODING ||
+        error->level != XML_ERR_WARNING ||
+        strcmp(error->message, "Unsupported encoding: #unsupported\n") != 0)
+    {
+        fprintf(stderr, "xmlReadDoc failed to raise correct error\n");
+        err = 1;
+    }
+
+    return err;
+}
+
 #ifdef LIBXML_SAX1_ENABLED
 static int
 testBalancedChunk(void) {
@@ -179,6 +207,7 @@ int
 main(void) {
     int err = 0;
 
+    err |= testUnsupportedEncoding();
 #ifdef LIBXML_SAX1_ENABLED
     err |= testBalancedChunk();
 #endif