xmlreader: Fix xmlTextReaderConstEncoding

Regression from commit f1c1f5c6.

Fixes #697.

SAX2.c

@@ -846,17 +846,7 @@ xmlSAX2EndDocument(void *ctx)
 
     doc = ctxt->myDoc;
     if ((doc != NULL) && (doc->encoding == NULL)) {
-        const xmlChar *encoding = NULL;
+        const xmlChar *encoding = xmlGetActualEncoding(ctxt);
-
-        if ((ctxt->input->flags & XML_INPUT_USES_ENC_DECL) ||
-            (ctxt->input->flags & XML_INPUT_AUTO_ENCODING)) {
-            /* Preserve encoding exactly */
-            encoding = ctxt->encoding;
-        } else if ((ctxt->input->buf) && (ctxt->input->buf->encoder)) {
-            encoding = BAD_CAST ctxt->input->buf->encoder->name;
-        } else if (ctxt->input->flags & XML_INPUT_HAS_ENCODING) {
-            encoding = BAD_CAST "UTF-8";
-        }
 
         if (encoding != NULL) {
             doc->encoding = xmlStrdup(encoding);

include/private/parser.h

@@ -68,6 +68,8 @@ XML_HIDDEN void
 xmlDetectEncoding(xmlParserCtxtPtr ctxt);
 XML_HIDDEN void
 xmlSetDeclaredEncoding(xmlParserCtxtPtr ctxt, xmlChar *encoding);
+XML_HIDDEN const xmlChar *
+xmlGetActualEncoding(xmlParserCtxtPtr ctxt);
 
 XML_HIDDEN xmlParserNsData *
 xmlParserNsCreate(void);

parserInternals.c

@@ -1398,6 +1398,30 @@ xmlSetDeclaredEncoding(xmlParserCtxtPtr ctxt, xmlChar *encoding) {
     ctxt->encoding = encoding;
 }
 
+/**
+ * xmlGetActualEncoding:
+ * @ctxt:  the parser context
+ *
+ * Returns the actual used to parse the document. This can differ from
+ * the declared encoding.
+ */
+const xmlChar *
+xmlGetActualEncoding(xmlParserCtxtPtr ctxt) {
+    const xmlChar *encoding = NULL;
+
+    if ((ctxt->input->flags & XML_INPUT_USES_ENC_DECL) ||
+        (ctxt->input->flags & XML_INPUT_AUTO_ENCODING)) {
+        /* Preserve encoding exactly */
+        encoding = ctxt->encoding;
+    } else if ((ctxt->input->buf) && (ctxt->input->buf->encoder)) {
+        encoding = BAD_CAST ctxt->input->buf->encoder->name;
+    } else if (ctxt->input->flags & XML_INPUT_HAS_ENCODING) {
+        encoding = BAD_CAST "UTF-8";
+    }
+
+    return(encoding);
+}
+
 /************************************************************************
  *									*
  *	Commodity functions to handle entities processing		*

testparser.c

@@ -176,7 +176,40 @@ testHtmlPushWithEncoding(void) {
 #endif
 #endif
 
-#if defined(LIBXML_READER_ENABLED) && defined(LIBXML_XINCLUDE_ENABLED)
+#ifdef LIBXML_READER_ENABLED
+static int
+testReaderEncoding(void) {
+    xmlBuffer *buf;
+    xmlTextReader *reader;
+    xmlChar *xml;
+    const xmlChar *encoding;
+    int err = 0;
+    int i;
+
+    buf = xmlBufferCreate();
+    xmlBufferCCat(buf, "<?xml version='1.0' encoding='ISO-8859-1'?>\n");
+    xmlBufferCCat(buf, "<doc>");
+    for (i = 0; i < 8192; i++)
+        xmlBufferCCat(buf, "x");
+    xmlBufferCCat(buf, "</doc>");
+    xml = xmlBufferDetach(buf);
+    xmlBufferFree(buf);
+
+    reader = xmlReaderForDoc(BAD_CAST xml, NULL, NULL, 0);
+    xmlTextReaderRead(reader);
+    encoding = xmlTextReaderConstEncoding(reader);
+
+    if (!xmlStrEqual(encoding, BAD_CAST "ISO-8859-1")) {
+        fprintf(stderr, "testReaderEncoding failed\n");
+        err = 1;
+    }
+
+    xmlFreeTextReader(reader);
+    xmlFree(xml);
+    return err;
+}
+
+#ifdef LIBXML_XINCLUDE_ENABLED
 typedef struct {
     char *message;
     int code;
@@ -254,6 +287,7 @@ testReaderXIncludeError(void) {
     return err;
 }
 #endif
+#endif
 
 #ifdef LIBXML_WRITER_ENABLED
 static int
@@ -314,9 +348,12 @@ main(void) {
     err |= testHtmlPushWithEncoding();
 #endif
 #endif
-#if defined(LIBXML_READER_ENABLED) && defined(LIBXML_XINCLUDE_ENABLED)
+#ifdef LIBXML_READER_ENABLED
+    err |= testReaderEncoding();
+#ifdef LIBXML_XINCLUDE_ENABLED
     err |= testReaderXIncludeError();
 #endif
+#endif
 #ifdef LIBXML_WRITER_ENABLED
     err |= testWriterClose();
 #endif

xmlreader.c

@@ -2866,20 +2866,17 @@ xmlTextReaderReadAttributeValue(xmlTextReaderPtr reader) {
  */
 const xmlChar *
 xmlTextReaderConstEncoding(xmlTextReaderPtr reader) {
-    xmlDocPtr doc = NULL;
+    const xmlChar *encoding = NULL;
-    if (reader == NULL)
-	return(NULL);
-    if (reader->doc != NULL)
-        doc = reader->doc;
-    else if (reader->ctxt != NULL)
-	doc = reader->ctxt->myDoc;
-    if (doc == NULL)
-	return(NULL);
 
-    if (doc->encoding == NULL)
+    if (reader == NULL)
-	return(NULL);
+        return(NULL);
-    else
+
-      return(CONSTSTR(doc->encoding));
+    if (reader->ctxt != NULL)
+        encoding = xmlGetActualEncoding(reader->ctxt);
+    else if (reader->doc != NULL)
+        encoding = reader->doc->encoding;
+
+    return(CONSTSTR(encoding));
 }