[libvirt] [PATCH] vsh: print help more often

[Peter Krempa]

On Wed, Oct 21, 2015 at 10:48:13 +0200, Michal Privoznik wrote:
> So, consider following scenario:
> 
>   virsh # migrate --help
> 
> In this case migrate help is printed out. So far so good.
> However, you start writing this long migrate command (I bet you
> know the arguments  there can get quite long), but then, at some
> point you need to print out the help. Something like this:
> 
>   virsh # migrate --copy-storage-all --migrate-disks --help
> 
> In this specific case you just want to see the format that
> --migrate-disks accepts. So you append --help and expect help to
> be printed out. Well, it will not, because "--help" is taken as
> data to --migrate-disks. Therefore we will get this error
> instead:
> 
>   virsh # migrate --copy-storage-all --migrate-disks --help
>   error: command 'migrate' requires <domain> option
>   error: command 'migrate' requires <desturi> option
> 
> Teach our parsing code, that --help may occur even in argument
> data, and therefore anywhere on the command line.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  tools/vsh.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 

The following then won't be possible:

$ virsh start --domain --help
Domain --help started

$ virsh list
 Id    Name                           State
----------------------------------------------------
 2     --help                         running

$ virsh destroy --domain --help
Domain --help destroyed


If you are curious whether such config is actually valid ...

 # virt-xml-validate /etc/libvirt/qemu/--help.xml 
/etc/libvirt/qemu/--help.xml validates

Since the schema looks like:
  <define name="domainName">
    <data type="string">
      <!-- Use literal newline instead of \n for bug in libxml2 2.7.6 -->
      <param name="pattern">[^
]+</param>
    </data>
  </define>

Peter
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