[libxml2] Fix xmlCtxtReadDoc with encoding

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 4ad71c2d72beef0d10cf75aa417db10d77846f75
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sat Aug 20 16:19:34 2022 +0200

    Fix xmlCtxtReadDoc with encoding
    
    xmlCtxtReadDoc used to create an input stream involving
    xmlNewStringInputStream. This would create a stream without an input
    buffer, causing problems with encodings (see #34).
    
    After commit aab584dc3, an error was returned even with UTF-8 encodings
    which happened to work before.
    
    Make xmlCtxtReadDoc call xmlCtxtReadMemory which doesn't suffer from
    these issues. Also fix htmlCtxtReadDoc.
    
    Fixes #397.

 HTMLparser.c | 17 ++++-------------
 parser.c     | 16 +++-------------
 2 files changed, 7 insertions(+), 26 deletions(-)
---
diff --git a/HTMLparser.c b/HTMLparser.c
index abc4e905..aef82c02 100644
--- a/HTMLparser.c
+++ b/HTMLparser.c
@@ -7116,22 +7116,13 @@ htmlDocPtr
 htmlCtxtReadDoc(htmlParserCtxtPtr ctxt, const xmlChar * cur,
                const char *URL, const char *encoding, int options)
 {
-    xmlParserInputPtr stream;
+    const char *buf;
 
     if (cur == NULL)
         return (NULL);
-    if (ctxt == NULL)
-        return (NULL);
-    xmlInitParser();
-
-    htmlCtxtReset(ctxt);
-
-    stream = xmlNewStringInputStream(ctxt, cur);
-    if (stream == NULL) {
-        return (NULL);
-    }
-    inputPush(ctxt, stream);
-    return (htmlDoRead(ctxt, URL, encoding, options, 1));
+    buf = (const char *) cur;
+    return (htmlCtxtReadMemory(ctxt, buf, strlen(buf), URL, encoding,
+                               options));
 }
 
 /**
diff --git a/parser.c b/parser.c
index e660b0a7..c313d88a 100644
--- a/parser.c
+++ b/parser.c
@@ -15359,22 +15359,12 @@ xmlDocPtr
 xmlCtxtReadDoc(xmlParserCtxtPtr ctxt, const xmlChar * cur,
                const char *URL, const char *encoding, int options)
 {
-    xmlParserInputPtr stream;
+    const char *buf;
 
     if (cur == NULL)
         return (NULL);
-    if (ctxt == NULL)
-        return (NULL);
-    xmlInitParser();
-
-    xmlCtxtReset(ctxt);
-
-    stream = xmlNewStringInputStream(ctxt, cur);
-    if (stream == NULL) {
-        return (NULL);
-    }
-    inputPush(ctxt, stream);
-    return (xmlDoRead(ctxt, URL, encoding, options, 1));
+    buf = (const char *) cur;
+    return (xmlCtxtReadMemory(ctxt, buf, strlen(buf), URL, encoding, options));
 }
 
 /**