[libxml2] Reset HTML parser input pointers on encoding failure

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 60173c821eff9e01f1b8bab4f722150a4c3cf82f
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Tue Sep 11 14:08:39 2018 +0200

    Reset HTML parser input pointers on encoding failure
    
    Call xmlBufResetInput before bailing out if switching the encoding
    fails. Otherwise, the input pointers could be left in an invalid state.
    
    Similar to commit f9e7997e803457b714352c4d51a96104ae298d94 for the
    XML parser.
    
    Thanks to Yunho Kim for the report.
    
    Closes: #27

 HTMLparser.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/HTMLparser.c b/HTMLparser.c
index 96a1bf40..9e60e27e 100644
--- a/HTMLparser.c
+++ b/HTMLparser.c
@@ -3636,12 +3636,12 @@ htmlCheckEncodingDirect(htmlParserCtxtPtr ctxt, const xmlChar *encoding) {
            processed = ctxt->input->cur - ctxt->input->base;
            xmlBufShrink(ctxt->input->buf->buffer, processed);
            nbchars = xmlCharEncInput(ctxt->input->buf, 1);
+            xmlBufResetInput(ctxt->input->buf->buffer, ctxt->input);
            if (nbchars < 0) {
                htmlParseErr(ctxt, XML_ERR_INVALID_ENCODING,
                             "htmlCheckEncoding: encoder error\n",
                             NULL, NULL);
            }
-            xmlBufResetInput(ctxt->input->buf->buffer, ctxt->input);
        }
     }
 }