Add options to ignore the internal encoding

For both XML and HTML, the document can provide an encoding
either in XMLDecl in XML, or as a meta element in HTML head.
This adds options to ignore those encodings if the encoding
is known in advace for example if the content had been converted
before being passed to the parser.

* parser.c include/libxml/parser.h: add XML_PARSE_IGNORE_ENC option
  for XML parsing
* include/libxml/HTMLparser.h HTMLparser.c: adds the
  HTML_PARSE_IGNORE_ENC for HTML parsing
* HTMLtree.c: fix the handling of saving when an unknown encoding is
  defined in meta document header
* xmllint.c: add a --noenc option to activate the new parser options

HTMLparser.c

@@ -3448,7 +3448,8 @@ static void
 htmlCheckEncoding(htmlParserCtxtPtr ctxt, const xmlChar *attvalue) {
     const xmlChar *encoding;
 
-    if ((ctxt == NULL) || (attvalue == NULL))
+    if ((ctxt == NULL) || (attvalue == NULL) ||
+        (ctxt->options & HTML_PARSE_IGNORE_ENC))
 	return;
 
     /* do not change encoding */
@@ -3500,7 +3501,9 @@ htmlCheckEncoding(htmlParserCtxtPtr ctxt, const xmlChar *attvalue) {
 		xmlSwitchToEncoding(ctxt, handler);
 		ctxt->charset = XML_CHAR_ENCODING_UTF8;
 	    } else {
-		ctxt->errNo = XML_ERR_UNSUPPORTED_ENCODING;
+		htmlParseErr(ctxt, XML_ERR_UNSUPPORTED_ENCODING,
+		             "htmlCheckEncoding: unknown encoding %s\n",
+			     encoding, NULL);
 	    }
 	}
 
@@ -6537,6 +6540,10 @@ htmlCtxtUseOptions(htmlParserCtxtPtr ctxt, int options)
 	ctxt->options |= HTML_PARSE_NODEFDTD;
         options -= HTML_PARSE_NODEFDTD;
     }
+    if (options & HTML_PARSE_IGNORE_ENC) {
+	ctxt->options |= HTML_PARSE_IGNORE_ENC;
+        options -= HTML_PARSE_IGNORE_ENC;
+    }
     ctxt->dictNames = 0;
     return (options);
 }

HTMLtree.c

@@ -481,7 +481,7 @@ htmlNodeDumpFileFormat(FILE *out, xmlDocPtr doc,
 	if (enc != XML_CHAR_ENCODING_UTF8) {
 	    handler = xmlFindCharEncodingHandler(encoding);
 	    if (handler == NULL)
-		return(-1);
+		htmlSaveErr(XML_SAVE_UNKNOWN_ENCODING, NULL, encoding);
 	}
     }
 
@@ -562,11 +562,9 @@ htmlDocDumpMemoryFormat(xmlDocPtr cur, xmlChar**mem, int *size, int format) {
 	    }
 
 	    handler = xmlFindCharEncodingHandler(encoding);
-	    if (handler == NULL) {
+	    if (handler == NULL)
-		*mem = NULL;
+                htmlSaveErr(XML_SAVE_UNKNOWN_ENCODING, NULL, encoding);
-		*size = 0;
+
-		return;
-	    }
 	} else {
 	    handler = xmlFindCharEncodingHandler(encoding);
 	}
@@ -587,7 +585,7 @@ htmlDocDumpMemoryFormat(xmlDocPtr cur, xmlChar**mem, int *size, int format) {
 	return;
     }
 
-	htmlDocContentDumpFormatOutput(buf, cur, NULL, format);
+    htmlDocContentDumpFormatOutput(buf, cur, NULL, format);
 
     xmlOutputBufferFlush(buf);
     if (buf->conv != NULL) {
@@ -1061,7 +1059,7 @@ htmlDocDump(FILE *f, xmlDocPtr cur) {
 
 	    handler = xmlFindCharEncodingHandler(encoding);
 	    if (handler == NULL)
-		return(-1);
+		htmlSaveErr(XML_SAVE_UNKNOWN_ENCODING, NULL, encoding);
 	} else {
 	    handler = xmlFindCharEncodingHandler(encoding);
 	}
@@ -1120,7 +1118,7 @@ htmlSaveFile(const char *filename, xmlDocPtr cur) {
 
 	    handler = xmlFindCharEncodingHandler(encoding);
 	    if (handler == NULL)
-		return(-1);
+		htmlSaveErr(XML_SAVE_UNKNOWN_ENCODING, NULL, encoding);
 	}
     }
 
@@ -1181,7 +1179,7 @@ htmlSaveFileFormat(const char *filename, xmlDocPtr cur,
 
 	    handler = xmlFindCharEncodingHandler(encoding);
 	    if (handler == NULL)
-		return(-1);
+		htmlSaveErr(XML_SAVE_UNKNOWN_ENCODING, NULL, encoding);
 	}
         htmlSetMetaEncoding(cur, (const xmlChar *) encoding);
     } else {

include/libxml/HTMLparser.h

@@ -184,7 +184,8 @@ typedef enum {
     HTML_PARSE_NOBLANKS	= 1<<8,	/* remove blank nodes */
     HTML_PARSE_NONET	= 1<<11,/* Forbid network access */
     HTML_PARSE_NOIMPLIED= 1<<13,/* Do not add implied html/body... elements */
-    HTML_PARSE_COMPACT  = 1<<16 /* compact small text nodes */
+    HTML_PARSE_COMPACT  = 1<<16,/* compact small text nodes */
+    HTML_PARSE_IGNORE_ENC=1<<21 /* ignore internal document encoding hint */
 } htmlParserOption;
 
 XMLPUBFUN void XMLCALL

include/libxml/parser.h

@@ -1105,8 +1105,9 @@ typedef enum {
 				   crash if you try to modify the tree) */
     XML_PARSE_OLD10	= 1<<17,/* parse using XML-1.0 before update 5 */
     XML_PARSE_NOBASEFIX = 1<<18,/* do not fixup XINCLUDE xml:base uris */
-    XML_PARSE_HUGE      = 1<<19, /* relax any hardcoded limit from the parser */
+    XML_PARSE_HUGE      = 1<<19,/* relax any hardcoded limit from the parser */
-    XML_PARSE_OLDSAX    = 1<<20 /* parse using SAX2 interface from before 2.7.0 */
+    XML_PARSE_OLDSAX    = 1<<20,/* parse using SAX2 interface before 2.7.0 */
+    XML_PARSE_IGNORE_ENC= 1<<21 /* ignore internal document encoding hint */
 } xmlParserOption;
 
 XMLPUBFUN void XMLCALL

parser.c

@@ -9922,6 +9922,13 @@ xmlParseEncodingDecl(xmlParserCtxtPtr ctxt) {
 	} else {
 	    xmlFatalErr(ctxt, XML_ERR_STRING_NOT_STARTED, NULL);
 	}
+
+        /*
+         * Non standard parsing, allowing the user to ignore encoding
+         */
+        if (ctxt->options & XML_PARSE_IGNORE_ENC)
+            return(encoding);
+
 	/*
 	 * UTF-16 encoding stwich has already taken place at this stage,
 	 * more over the little-endian/big-endian selection is already done
@@ -14561,6 +14568,10 @@ xmlCtxtUseOptionsInternal(xmlParserCtxtPtr ctxt, int options, const char *encodi
 	ctxt->options |= XML_PARSE_OLDSAX;
         options -= XML_PARSE_OLDSAX;
     }
+    if (options & XML_PARSE_IGNORE_ENC) {
+	ctxt->options |= XML_PARSE_IGNORE_ENC;
+        options -= XML_PARSE_IGNORE_ENC;
+    }
     ctxt->linenumbers = 1;
     return (options);
 }

xmllint.c

@@ -130,6 +130,7 @@ static int copy = 0;
 #endif /* LIBXML_TREE_ENABLED */
 static int recovery = 0;
 static int noent = 0;
+static int noenc = 0;
 static int noblanks = 0;
 static int noout = 0;
 static int nowrap = 0;
@@ -2983,6 +2984,7 @@ static void usage(const char *name) {
     printf("\t--recover : output what was parsable on broken XML documents\n");
     printf("\t--huge : remove any internal arbitrary parser limits\n");
     printf("\t--noent : substitute entity references by their value\n");
+    printf("\t--noenc : ignore any encoding specified inside the document\n");
     printf("\t--noout : don't output the result tree\n");
     printf("\t--path 'paths': provide a set of paths for resources\n");
     printf("\t--load-trace : print trace of all external entites loaded\n");
@@ -3137,6 +3139,10 @@ main(int argc, char **argv) {
 	         (!strcmp(argv[i], "--noent"))) {
 	    noent++;
 	    options |= XML_PARSE_NOENT;
+	} else if ((!strcmp(argv[i], "-noenc")) ||
+	         (!strcmp(argv[i], "--noenc"))) {
+	    noenc++;
+	    options |= XML_PARSE_IGNORE_ENC;
 	} else if ((!strcmp(argv[i], "-nsclean")) ||
 	         (!strcmp(argv[i], "--nsclean"))) {
 	    options |= XML_PARSE_NSCLEAN;