migrate_send API call accepted withoutvgpu_map argument and warns only when all is over

[stormi]

From the API docs:

VM ref migrate_send (session ref, VM ref, (string → string) map, bool, (VDI ref → SR ref) map, (VIF ref → network ref) map, (string → string) map, (VGPU ref → GPU_group ref) map) 

(VGPU ref → GPU_group ref) map vgpu_map | Map of source vGPU to destination GPU group

When the vgpu_map parameter is missing, the migrate_send call is still processed and completes well if there's no vgpu. However a warning appears in the logs ("cannot marshall arguments"):

/var/log/xensource.log.1:35182:Jul 15 15:06:55 <host> xapi: [ warn|<host>|178440 |Async.VM.migrate_send R:3793418e587b|rbac_audit] cannot marshall arguments for the action VM.migrate_send: name and value list lengths don't match. str_names=[session_id,vm,dest,live,vdi_map,vif_map,options,vgpu_map,], xml_values=[S(OpaqueRef:934aaee6-cf8e-436f-8396-ae93d8745db6),S(OpaqueRef:06934e5f-04ca-4ff9-96a8-fe8a244d4fce),{SM:S(http://<ip>/services/SM?session_id=OpaqueRef:2b31dd59-acf2-473c-8c04-c3040b8a1301);host:S(OpaqueRef:076a9aca-5df0-47dc-a050-21fbb96abfda);xenops:S(http://<ip>/services/xenops?session_id=OpaqueRef:2b31dd59-acf2-473c-8c04-c3040b8a1301);session_id:S(OpaqueRef:2b31dd59-acf2-473c-8c04-c3040b8a1301);master:S(http://<ip>/)},B(true),{OpaqueRef:b622ba46-ea56-4a27-80a4-fce6e5e6d7d3:S(OpaqueRef:b9c12444-c03d-4808-980c-d64c220465c4)},{},{force:S(true)},]

From what I understand, either the argument is mandatory and then the API call should fail without it, or it is optional and then an empty map should be added to avoid the error.

[robhoes]

I have noticed this too, and I am not sure why it happens. I think it is just the audit logging though; the argument is treated as optional.

[edwintorok]

The problem seems to be here: https://github.com/xapi-project/xen-api/blob/v1.184.0/ocaml/xapi/rbac_audit.ml#L360-L394
The code uses a fold_right2 which requires matching list lengths, and if there are any optional arguments then it gives up, warns and returns the empty list. It is not specific to this API call, should happen on any API call with optional arguments.

[psafont]

This was fixed by #4829