[libvirt] [PATCH] virsh: use virConnectGetDomainCapabilities with maxvcpus

[Shivaprasad G Bhat]

Hi Peter,

This saves few lines of code for sure :) I see the ignore_error for 
virXPathInt(). I see no issues.

ACK

Thanks a lot!

-Shivaprasad

On 09/15/2016 01:47 PM, Peter Krempa wrote:
> From: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
>
> virsh maxvcpus --type kvm output is useless on PPC. Also, in
> commit e6806d79 we documented not rely on virConnectGetMaxVcpus
> output. Fix the  maxvcpus to use virConnectGetDomainCapabilities
> now to make it useful. The call is made to use the default emulator
> binary and to check for the host machine and arch which is what the
> command intends to show anyway.
>
> Signed-off-by: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
> ---
>   tools/virsh-host.c | 30 ++++++++++++++++++++++++++----
>   1 file changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/tools/virsh-host.c b/tools/virsh-host.c
> index 57f0c0e..2337ce8 100644
> --- a/tools/virsh-host.c
> +++ b/tools/virsh-host.c
> @@ -606,18 +606,40 @@ static bool
>   cmdMaxvcpus(vshControl *ctl, const vshCmd *cmd)
>   {
>       const char *type = NULL;
> -    int vcpus;
> +    int vcpus = -1;
> +    char *caps = NULL;
> +    xmlDocPtr xml = NULL;
> +    xmlXPathContextPtr ctxt = NULL;
>       virshControlPtr priv = ctl->privData;
> +    bool ret = false;
>
>       if (vshCommandOptStringReq(ctl, cmd, "type", &type) < 0)
>           return false;
>
> -    if ((vcpus = virConnectGetMaxVcpus(priv->conn, type)) < 0)
> -        return false;
> +    if ((caps = virConnectGetDomainCapabilities(priv->conn, NULL, NULL, NULL,
> +                                                type, 0))) {
> +        if (!(xml = virXMLParseStringCtxt(caps, _("(domainCapabilities)"), &ctxt)))
> +            goto cleanup;
> +
> +        ignore_value(virXPathInt("string(./vcpu[1]/@max)", ctxt, &vcpus));
> +    } else {
> +        if (last_error && last_error->code != VIR_ERR_NO_SUPPORT)
> +            goto cleanup;
> +
> +       vshResetLibvirtError();
> +    }
> +
> +    if (vcpus < 0 && (vcpus = virConnectGetMaxVcpus(priv->conn, type)) < 0)
> +        goto cleanup;
>
>       vshPrint(ctl, "%d\n", vcpus);
> +    ret = true;
>
> -    return true;
> + cleanup:
> +    xmlXPathFreeContext(ctxt);
> +    xmlFreeDoc(xml);
> +    VIR_FREE(caps);
> +    return ret;
>   }
>
>   /*