Add status and action strings, and func to retrieve them, including formatting option

[deitch]

As discussed in #41

[deitch]

The only thing I didn't include is where it actually reports which features are unsupported, see here and here.

To do that, I would need to know what part of go-libzfs I would use to find the unsupported features for the equivalent of zpool_print_unsup_feat, which is defined here, imported for libzfs.h.

If I can get some pointers, happy to include it, or we can make it a future iteration.

[fkasumovic]

zpool_print_unsup_feat is not used, and if you going to do it,
do it in the next iteration, and please don't print :-).

Because libzfs C library (wrapped in go here) is not designed as an actual general-purpose API for ZFS but rather as a part of user-space utils of the ZFS, it has these awkward printing functions for the library :-). There is libzfs_core that suppose to be a general-purpose library but does not support all the features and so it's not used here until that changes.

Implement the Pool type method to return a list of unsupported features, and then the developer using go-libzfs can choose to print it or whatever.

func (p *Pool) UnsupportedFeatures() (features map[string]string) {
...
}

[deitch]

zpool_print_unsup_feat is not used, and if you going to do it,
do it in the next iteration, and please don't print :-).

OK, I replace the "it uses the following feature(s) not supported on this system:" part for that message with "it uses feature(s) not supported on this system."

That makes it correct grammatically, while leaving it open in the future to add those details, like you suggested.

Ready for another review.

[deitch]

Implement the Pool type method to return a list of unsupported features, and then the developer using go-libzfs can choose to print it or whatever.

func (p *Pool) UnsupportedFeatures() (features map[string]string) {
...
}

I rather like that idea. But I do not know what goes in that function. The original source for it appears to be in this thankfully short function, but unsure what it is doing.

[fkasumovic]

@deitch Well when I take a better look, I think unsupported features is available only for exported pool,

So maybe this should be added in to PoolImportSearch, and returned as a part of ExportedPool type/struct.

ep.Status = PoolStatus(reason)
ep.UnsupportedFeatures = unsupportedFeatures(config)

You can wrap with cgo, implementation for fetching the list would probably look like the following:

func unsupportedFeatures(config C.nvlist_ptr) (features map[string]string) {
	features = make(map[string]string)
	var nvinfo, unsup_feat C.nvlist_ptr

	if C.nvlist_exists(config, C.sZPOOL_CONFIG_LOAD_INFO) != 0 {
		nvinfo = C.fnvlist_lookup_nvlist(config, C.sZPOOL_CONFIG_LOAD_INFO)
		if C.nvlist_exists(nvinfo, C.sZPOOL_CONFIG_UNSUP_FEAT) != 0 {
			unsup_feat = C.fnvlist_lookup_nvlist(nvinfo, C.sZPOOL_CONFIG_UNSUP_FEAT)

			for nvp := C.nvlist_next_nvpair(unsup_feat, nil); nvp != nil; {
				desc := C.GoString(C.fnvpair_value_string(nvp))
				name := C.GoString(C.nvpair_name(nvp))
				features[name] = desc

				nvp = C.nvlist_next_nvpair(unsup_feat, nil)
			}
		}
	}
	return
}

And then do lot of testing :-)

[deitch]

I hadn't even thought of that, just of recreating the logic. What you did is much smoother. You already pretty much did it.