parser: Make unsupported encodings an error in declarations

This was changed in 4515726, but in encoding declarations, unsupported
encodings should raise a fatal error.

Fixes #794.

Author: nwellnhof

parserInternals.c

@@ -364,20 +364,14 @@ void
 xmlFatalErr(xmlParserCtxtPtr ctxt, xmlParserErrors code, const char *info)
 {
     const char *errmsg;
-    xmlErrorLevel level;
-
-    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, code, level,
+        xmlCtxtErr(ctxt, NULL, XML_FROM_PARSER, code, XML_ERR_FATAL,
                    NULL, NULL, NULL, 0, "%s\n", errmsg);
     } else {
-        xmlCtxtErr(ctxt, NULL, XML_FROM_PARSER, code, level,
+        xmlCtxtErr(ctxt, NULL, XML_FROM_PARSER, code, XML_ERR_FATAL,
                    (const xmlChar *) info, NULL, NULL, 0,
                    "%s: %s\n", errmsg, info);
     }
@@ -1122,7 +1116,11 @@ xmlSwitchInputEncodingName(xmlParserCtxtPtr ctxt, xmlParserInputPtr input,
         return(-1);
 
     res = xmlOpenCharEncodingHandler(encoding, /* output */ 0, &handler);
-    if (res != 0) {
+    if (res == XML_ERR_UNSUPPORTED_ENCODING) {
+        xmlWarningMsg(ctxt, XML_ERR_UNSUPPORTED_ENCODING,
+                      "Unsupported encoding: %s\n", BAD_CAST encoding, NULL);
+        return(-1);
+    } else if (res != XML_ERR_OK) {
         xmlFatalErr(ctxt, res, encoding);
         return(-1);
     }
@@ -1383,7 +1381,28 @@ void
 xmlSetDeclaredEncoding(xmlParserCtxtPtr ctxt, xmlChar *encoding) {
     if (((ctxt->input->flags & XML_INPUT_HAS_ENCODING) == 0) &&
         ((ctxt->options & XML_PARSE_IGNORE_ENC) == 0)) {
-        xmlSwitchEncodingName(ctxt, (const char *) encoding);
+        xmlCharEncodingHandlerPtr handler;
+        int res;
+
+        /*
+         * xmlSwitchInputEncodingName treats unsupported encodings as
+         * warnings, but we want it to be an error in an encoding
+         * declaration.
+         */
+        res = xmlOpenCharEncodingHandler((const char *) encoding,
+                /* output */ 0, &handler);
+        if (res != XML_ERR_OK) {
+            xmlFatalErr(ctxt, res, (const char *) encoding);
+            xmlFree(encoding);
+            return;
+        }
+
+        res  = xmlSwitchInputEncoding(ctxt, ctxt->input, handler);
+        if (res != XML_ERR_OK) {
+            xmlFree(encoding);
+            return;
+        }
+
         ctxt->input->flags |= XML_INPUT_USES_ENC_DECL;
     } else if (ctxt->input->flags & XML_INPUT_AUTO_ENCODING) {
         static const char *allowedUTF8[] = {

result/errors/unsupported-encoding.xml.ent

@@ -0,0 +1,3 @@
+./test/errors/unsupported-encoding.xml:1: parser error : Unsupported encoding: unsupported-encoding
+<?xml version="1.0" encoding="unsupported-encoding"?>
+                                                   ^

result/errors/unsupported-encoding.xml.err

@@ -0,0 +1,3 @@
+./test/errors/unsupported-encoding.xml:1: parser error : Unsupported encoding: unsupported-encoding
+<?xml version="1.0" encoding="unsupported-encoding"?>
+                                                   ^

result/errors/unsupported-encoding.xml.str

@@ -0,0 +1,4 @@
+./test/errors/unsupported-encoding.xml:1: parser error : Unsupported encoding: unsupported-encoding
+<?xml version="1.0" encoding="unsupported-encoding"?>
+                                                   ^
+./test/errors/unsupported-encoding.xml : failed to parse

test/errors/unsupported-encoding.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="unsupported-encoding"?>
+<doc/>