[libvirt] [PATCH 08/11] tools: Provide bash autompletion file

[Eric Blake]

On 11/08/2017 10:06 AM, Michal Privoznik wrote:

>> $ virsh complete some-command --arg partial<TAB><TAB>
> 
> This is excatly what my patches are doing. With one tiny difference. In
> fact bash script calls:
> 
>   virsh complete "some-command --arg partial"
> 
> so that I can have cmdComplete which takes exactly one string argument.

Ouch. That difference matters, and I don't think you want to do that.

We don't want to reimplement shell parsing; if the user does:

virsh snapshot-create-as 'domain with space' 'name with space'
'description with space', then my approach feeds those three arguments
as is (the virsh parser doesn't have to undo any shell quoting), while
your approach HAS to over-quote the original command line, then
reimplement shell quoting to remove those quotes in virsh, in order to
reconstruct the original line in spite of being temporarily squashed
through one argument.

> Parsing of the string is then done within cmdComplete. I don't think
> that we have variable args in virsh for commands, do we?

Yes, we do.  See 'virsh echo' for an example of its use.

> 
> Correct. And again, my patches do this. For instance:
> 
>   virsh -r -c qemu+ssh://host/system domifaddr --domain<TAB><TAB>
> 
> becomes:
> 
>   virsh -r -c qemu+ssh://host/system complete "domifaddr --domain"
> 
> And it's the 'complete' command that is responsible for bringing up a
> list of possible strings.

Ah, you are trying to put 'complete' after virsh-specific options (-r,
-c), but before the command (domifaddr).

And if properly implemented, you should be able to have:

virsh domif<TAB><TAB>

show 'domifaddr' (and any other commands starting with 'domif') (by
calling "virsh complete -- domif"),

virsh domifaddr <TAB><TAB>

show both a list of domain names AND a list of --options accepted by
domifaddr (by calling "virsh complete -- domifaddr ''"),

virsh domifaddr --<TAB><TAB>

show a list of long options for domifaddr (by calling "virsh complete --
domifaddr --") (yes, I'm specifically making sure the second '--'
doesn't get eaten by getopts, by inserting 'complete --' rather than
just 'complete'), and

virsh domifaddr a<TAB><TAB>

show a filtered list of just domain names starting with 'a' (by calling
"virsh complete domifaddr a").

That is, the completions should be context-sensitive based on how much
of the command line is present prior to the <TAB><TAB>, and should NOT
need the user to type an explicit --domain just to get domain completions.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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