Moved some code from mxwriter ISAXContentHandler implementation into free functions that can be swapped out for DOMDocument functions.

For other mxwriter callback functions, immediately return E_NOTIMPL if the destination is a DOMDocument.

Added test_mxwriter_domdoc_start_end_document to help check the implementation of DOMDocument locking.

Added "BOOL locked" to XML documents and a private interface that allows this variable to be set and checked.  (This variable is not used thread safely.  `LONG refs` is thread safe, but `struct list orphans` is not.)


thanks,
Jefferson

@@ -125,6 +125,7 @@ struct domdoc
     IPersistStreamInit        IPersistStreamInit_iface;
     IObjectWithSite           IObjectWithSite_iface;
     IObjectSafety             IObjectSafety_iface;
+    IWineXMLDOMDocumentLock   IWineXMLDOMDocumentLock_iface;
     IConnectionPointContainer IConnectionPointContainer_iface;
     LONG ref;
     VARIANT_BOOL async;

@@ -209,6 +210,7 @@ typedef struct _xmldoc_priv {
     LONG refs;
     struct list orphans;
     domdoc_properties* properties;
+    BOOL locked;
 } xmldoc_priv;

diff --git a/dlls/msxml3/node.c b/dlls/msxml3/node.c
index 67f322eb0e5..9cbb2305830 100644
--- a/dlls/msxml3/node.c
+++ b/dlls/msxml3/node.c
@@ -457,6 +457,8 @@ HRESULT node_insert_before(xmlnode *This, IXMLDOMNode *new_child, const VARIANT
     if(!new_child)
         return E_INVALIDARG;
 
+    if (xmldoc_get_locked(This->node->doc)) return E_FAIL;
+
     node_obj = get_node_obj(new_child);
     if(!node_obj) return E_FAIL;
 
@@ -569,6 +571,8 @@ HRESULT node_replace_child(xmlnode *This, IXMLDOMNode *newChild, IXMLDOMNode *ol
     if(!newChild || !oldChild)
         return E_INVALIDARG;
 
+    if (xmldoc_get_locked(This->node->doc)) return E_FAIL;
+
     if(ret)
         *ret = NULL;
 
@@ -627,6 +631,8 @@ HRESULT node_remove_child(xmlnode *This, IXMLDOMNode* child, IXMLDOMNode** oldCh
 
     if(!child) return E_INVALIDARG;
 
+    if (xmldoc_get_locked(This->node->doc)) return E_FAIL;
+
     if(oldChild)
         *oldChild = NULL;

+static HRESULT writer_end_tag_domdoc(mxwriter *writer, const WCHAR *qname, int len) {
+    HRESULT hr;
+    IXMLDOMNode *parent_node;
+
+    IWineXMLDOMDocumentLock_put_locked(writer->doc_lock, 0);
+
+    hr = domdoc_maybe_write_chars(writer);
+    if (FAILED(hr)) return hr;
+
+    IWineXMLDOMDocumentLock_put_locked(writer->doc_lock, 1);
+
+    hr = IXMLDOMNode_get_parentNode(writer->current_node, &parent_node);
+    if (FAILED(hr)) return hr;
+
+    IXMLDOMNode_Release(writer->current_node);
+    writer->current_node = parent_node;
+    return hr;
+}

+static HRESULT writer_start_tag_string_len_stream(mxwriter *writer, const WCHAR *qname, int len)
+{
+    static const WCHAR ltW[] = {'<'};
+
+    close_element_starttag(writer);
+    set_element_name(writer, qname ? qname : emptyW, qname ? len : 0);
+
+    write_node_indent(writer);
+
+    write_output_buffer(writer, ltW, 1);
+    write_output_buffer(writer, qname ? qname : emptyW, qname ? len : 0);
+    writer_inc_indent(writer);
+
+    return S_OK;
+}
+
+static HRESULT writer_start_tag_bstr_stream(mxwriter *writer, BSTR name)
+{
+    return writer_start_tag_string_len_stream(writer, name, SysStringLen(name));
+}
+