arv_dom_document_get_url is always NULL

[eudoxos]

Describe the bug
There is a function to retrieve URL of the genicam XML: arv_dom_document_get_url; it returns ArvDomDocumentPrivate's url attribute, assigned in arv_dom_document_new_from_url.

This codepath is not currently used at all, though. Instead, arv_gc_new receives already loaded XML; the loading happens in _load_genicam which only returns the XML content but does not store its URL (obtained with arv_gv_device_read_memory at ARV_GVBS_XML_URL_SIZE). That is why arv_dom_document_get_url return NULL (as far as I understand).

Expected behavior
arv_dom_document_get_url returns URL (such as Local:genicam.xml;123;456, 123 being address and 456 size) which can be parsed and used to retrieve the XML from memory again (for GigeV, USB and Fake cameras).

Platform description:

• Aravis version: git
• OS: Mint 21.1
• Hardware: x86_64

Additional context
This is needed for the GenTL provider so that it does not duplicate code from other parts of Aravis. GenTL consumers download and interpret the XML themselves, and use URL to request them via memory access.

[EmmanuelP]

Please try #835.

[eudoxos]

Excellent, #835 really helps!