Apologies for the long read in advance, I am trying to keep it as succinct as possible. Feel free to ask me to elaborate on some aspects, or to edit and remove some parts to enhance this question.
Background:
We have an application that can interface with lots of modules (daemon).
Each module is configured from XML in a database.
We sometimes have to debug issues when someone has been manually editing the XML configuration (at HQ and on site), so I have taken it upon myself to validate the XML at runtime, so we can catch these configuration issues earlier:
/*---------------------------------------------------------------------------
**
*/
bool BaseApplication::validateXML(const QDomDocument& doc, const QString& schema)
{
QFile xsdfile(schema);
if (xsdfile.open(QFile::ReadOnly)) {
QXmlSchema xsd;
xsd.load(&xsdfile);
if (xsd.isValid()) {
QXmlSchemaValidator validator(xsd);
const QString xml = doc.toString();
return validator.validate(xml.toLatin1());
}
else {
qWarning("BaseApplication::validateXML() - schema \"%s\" is not well-formed", qPrintable(schema));
}
}
else {
qWarning("BaseApplication::validateXML() - unable to open schema \"%s\"", qPrintable(schema));
}
return false;
}
All modules have an application class that derives from this BaseApplication. It's part of a larger framework.
So an application at bootstrap could do something like:
void Application::preBegin()
{
...
const QDomDocument config = // load XML from database
if (!validateXML(config, ":schema.xsd")) {
qFatal("Application::preBegin() - configuration is not valid");
}
...
}
But doing so remains completely optional (per module). This all works fine in our engineering environment.
The problem:
For {reasons too complicated and distracting} the department that sets up and maintains the larger customer systems have written scripts that generate the various module XML configurations to include (among others) noNamespaceSchemaLocation.
So instead of a typical module configuration looking like this:
<configuration>
<!--XML struct here-->
</configuration>
They are written like:
<configuration xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" schema_version="1" xsi:noNamespaceSchemaLocation="{url to XSD file on intranet server}">
<!--XML struct here-->
</configuration>
(modules regard these extra attributes as meta-data)
This causes an issue for modules that have built-in XSD validation. At runtime during the loading and validation of the module's XML configuration we see odd behaviour (UB?). Even though this is a synchronous process in a single thread, the debug log shows events occurring before Application::preBegin() that should be happening afterwards.
We also see a full minute (to the second) being lost in XML validation.
Manually removing the noNamespaceSchemaLocation attribute from the root object fixes this issue. Validation then happens in next-to-no-time and events happen in the right sequence according to the log.
The question:
Is there anything I can add to /call in BaseApplication::validateXML() that could cause the routine to ignore any mentions of noNamespaceSchemaLocation in the XML it is trying to validate?
