base-uri#1 not set correctly

[PieterLamers]

Describe the bug
When trying to get fn:transform#1 to behave in our environment, we found that base-uri#1 did not return what we expected. Rather than returning the path it returned /db.
BTW document-uri#1 did return the path, so that served as a workaround.

Expected behavior
We expect the path to $doc to be returned when calling base-uri($doc).

To Reproduce
With any document path:

let $disk-path as xs:string := 'file:///C:/intranet/components/benjamins.com/xsl/general-web-templates.xsl'
let $doc as document-node() := doc($disk-path)
return base-uri($doc)

Context (please always complete the following information)

• Version: [Elemental 6.9.0]
• Java: various
• OS: Windows 11, Linux

We did not check whether a similar problem exists for in memory documents. Also, there is another open issue regarding fn:transform, #169 which might be related to this one.

[nverwer]

I think the problem is in org.exists.dom.memtree.DocumentImpl, in the getBaseURI() method. This first thing it does is final Element el = getDocumentElement();. If el != null, which is true if the document has a root element, it determines the attribute value getAttributeNS(Namespaces.XML_NS, "base"). This makes sense, but the attribute value is the empty string, and the test in the following line is if(baseURI != null). Thus, "" is returned, and in FunBaseURI this is replaced by the contextBaseURI.

My suggestion would be to use hasAttributeNS in the first few lines of getBaseURI() in org.exist.dom.memtree.DocumentImpl:

    public String getBaseURI() {
        final Element el = getDocumentElement();
        if (el != null) {
            if (el.hasAttributeNS(Namespaces.XML_NS, "base")) {
                final String baseURI = el.getAttributeNS(Namespaces.XML_NS, "base");
                return baseURI;
            }
        }