Re: [xml] userdata for SAX parsing with schema validation

On 23/12/2021 20:14, Lara Blatchford wrote:
Hi - I have a simple SAX handler set up, and schema validation errors are being caught by my structured error handler.  So far so good.

It appears that the userdata argument to xmlSAXUserParseMemory /must/ be the xmlSchemaSAXPlugPtr returned by the call to xmlSchemaSAXPlug, and that this pointer is passed as the ctx pointer to the SAX handler callbacks.

This is correct.

Is there any way for me to make a userdata pointer of my choosing available to my SAX handler callbacks while still getting schema validation?

From a quick look at the code, it seems that you can simply pass your user data pointer to xmlSchemaSAXPlug.

    // userdata arg is set to the pointer to the original SAX user data pointer

    xmlSchemaValidCtxtPtr oldXsdValidCtxt = NULL;;

    void *ctxptr = &oldXsdValidCtxt;

   xmlSchemaSAXPlugPtr saxPlug = xmlSchemaSAXPlug(xsdValidCtxt, &schemaValHandler, &ctxptr );

You should pass your user data pointer here instead of a NULL xmlSchemaValidCtxtPtr:

    void *user_data = my_user_data;
    xmlSchemaSAXPlugPtr saxPlug = xmlSchemaSAXPlug(xsdValidCtxt,
        &schemaValHandler, &user_data);

xmlSchemaSAXPlug will then swap the user data pointer with its own one which you have to use when calling xmlSAXUserParseMemory. The SAX callbacks, however, should receive the original pointer.


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