[libvirt] [PATCH v4] virsh: add [--domain DOMAIN] option to domxml-to-native DOMAIN COMMAND

[John Ferlan]

On 06/02/2017 11:04 AM, Daniel Liu wrote:
> The option allows someone to run domain-to-native on already existing
> domain without the need of supplying their XML.  It is basically
> wrapper around 'virsh dumpxml  | virsh domxml-to-native /dev/stdin'.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=835476
> Signed-off-by: Daniel Liu <srwx4096 at gmail.com>
> ---
>  tools/virsh-domain.c | 51 ++++++++++++++++++++++++++++++++++++++-------------
>  tools/virsh.pod      |  7 ++++---
>  2 files changed, 42 insertions(+), 16 deletions(-)
> 
> diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
> index ccb514ef9..3496359c5 100644
> --- a/tools/virsh-domain.c
> +++ b/tools/virsh-domain.c
> @@ -9848,9 +9848,13 @@ static const vshCmdOptDef opts_domxmltonative[] = {
>       .flags = VSH_OFLAG_REQ,
>       .help = N_("target config data type format")
>      },
> +    {.name = "domain",
> +     .type = VSH_OT_DATA,
> +     .flags = VSH_OFLAG_REQ_OPT,
> +     .help = N_("domain name, id or uuid")
> +    },
>      {.name = "xml",
>       .type = VSH_OT_DATA,
> -     .flags = VSH_OFLAG_REQ,
>       .help = N_("xml data file to export from")
>      },
>      {.name = NULL}
> @@ -9859,30 +9863,51 @@ static const vshCmdOptDef opts_domxmltonative[] = {
>  static bool
>  cmdDomXMLToNative(vshControl *ctl, const vshCmd *cmd)
>  {
> -    bool ret = true;
> +    bool ret = false;
>      const char *format = NULL;
> -    const char *xmlFile = NULL;
> -    char *configData;
> -    char *xmlData;
> +    const char *xml = NULL;

nit: no need to change from xmlFile to xml... The less differences the
better ;-)

> +    char *xmlData = NULL;
> +    char *configData = NULL;

nit: no need to change order from original, just add ' = NULL' is fine.

>      unsigned int flags = 0;
>      virshControlPtr priv = ctl->privData;
> +    virDomainPtr dom = NULL;
>  
>      if (vshCommandOptStringReq(ctl, cmd, "format", &format) < 0 ||
> -        vshCommandOptStringReq(ctl, cmd, "xml", &xmlFile) < 0)
> +        vshCommandOptStringReq(ctl, cmd, "xml", &xml) < 0)
>          return false;
>  
> -    if (virFileReadAll(xmlFile, VSH_MAX_XML_FILE, &xmlData) < 0)
> -        return false;
> +    VSH_EXCLUSIVE_OPTIONS("domain", "xml");
>  
> -    configData = virConnectDomainXMLToNative(priv->conn, format, xmlData, flags);
> -    if (configData != NULL) {
> -        vshPrint(ctl, "%s", configData);
> -        VIR_FREE(configData);
> +    if (vshCommandOptBool(cmd, "domain") &&
> +        (!(dom = virshCommandOptDomain(ctl, cmd, NULL))))
> +            return false;
> +
> +    if (dom) {
> +        xmlData = virDomainGetXMLDesc(dom, flags);
> +    } else if (xml) {
> +        if (virFileReadAll(xml, VSH_MAX_XML_FILE, &xmlData) < 0)
> +            goto cleanup;
>      } else {
> -        ret = false;
> +        vshError(ctl, "%s", _("need either domain or domain XML"));
> +        goto cleanup;
> +    }
> +
> +    if (!xmlData) {
> +        vshError(ctl, "%s", _("failed to retrieve XML"));
> +        goto cleanup;
>      }
>  
> +    if (!(configData = virConnectDomainXMLToNative(priv->conn, format, xmlData, flags))) {
> +        goto cleanup;
> +    } else {
> +        vshPrint(ctl, "%s", configData);
> +        ret = true;
> +    }
> +
> + cleanup:
> +    virshDomainFree(dom);
>      VIR_FREE(xmlData);
> +    VIR_FREE(configData);
>      return ret;
>  }
>  
> diff --git a/tools/virsh.pod b/tools/virsh.pod
> index aee964689..049c2f3c7 100644
> --- a/tools/virsh.pod
> +++ b/tools/virsh.pod
> @@ -1433,10 +1433,11 @@ the I<format> argument must be B<qemu-argv>. For Xen hypervisor, the
>  I<format> argument may be B<xen-xm>, B<xen-xl>, or B<xen-sxpr>. For
>  LXC hypervisor, the I<format> argument must be B<lxc-tools>.
>  
> -=item B<domxml-to-native> I<format> I<xml>
> +=item B<domxml-to-native> I<format>
> +{ I<--domain> I<domain-name-or-id-or-uuid> | [I<--xml>] I<xml> }

This looks really odd, I think this should be

{ [I<xml> | [I<--domain> I<domain-name-or-id-uuid>] }

I believe that's the way to describe mutually exclusive options where
one would be required; otherwise, we have the funky [[ ... ]] which
indicates mutually exclusive optional arguments. Search on "{ [" in
virsh.pod for some examples. This seems to be the first case where a
previously required positional argument can be both a positional and
optional as long as the alternative means of describing is provided.

Keeping the I<xml> first at least indicates that it can be used
*without* the --xml, but is also the "default" when used positionally on
the command line. If not used positionally, then the --xml would be
required, e.g. if someone used "virsh domxml-to-native --xml @file
--format @format".

Having the [--domain] indicates that in order to use it, it must have
that --domain argument because "virsh domxml-to-native qemu-argv
$domainname" would be invalid since the unqualified 2nd argument is
expected to be an <xml> file.

Whether any of this is written down anywhere - I'm not sure - it's what
I've surmised over the few years.


>  
> -Convert the file I<xml> in domain XML format to the native guest
> -configuration format named by I<format>. For QEMU/KVM hypervisor,
> +Convert the file I<xml> in domain XML format or existing domain to the
> +native guest configuration format named by I<format>. For QEMU/KVM hypervisor,
>  the I<format> argument must be B<qemu-argv>. For Xen hypervisor, the
>  I<format> argument may be B<xen-xm>, B<xen-xl>, or B<xen-sxpr>. For
>  LXC hypervisor, the I<format> argument must be B<lxc-tools>.
> 

Convert the file I<xml> into domain XML format or convert an existing
I<--domain> to the native guest configuration format named by I<format>.
The I<xml> and I<--domain> arguments are mutually exclusive.

John