[libvirt] [PATCHv2 4/4] snapshot: expose location through virsh snapshot-info

[Peter Krempa]

On 11/15/12 00:36, Eric Blake wrote:
> Now that we can filter on this information, we should also make
> it easy to get at.
>
> * tools/virsh-snapshot.c (cmdSnapshotInfo): Add another output
> row, and switch to XPath queries rather than strstr.
> ---
>   tools/virsh-snapshot.c | 57 +++++++++++++++++++++++++++++++++++++++++++-------
>   1 file changed, 49 insertions(+), 8 deletions(-)
>
> diff --git a/tools/virsh-snapshot.c b/tools/virsh-snapshot.c
> index 7cd2966..36f5b46 100644
> --- a/tools/virsh-snapshot.c
> +++ b/tools/virsh-snapshot.c
> @@ -797,7 +797,10 @@ cmdSnapshotInfo(vshControl *ctl, const vshCmd *cmd)
>       virDomainSnapshotPtr snapshot = NULL;
>       const char *name;
>       char *doc = NULL;
> -    char *tmp;
> +    xmlDocPtr xmldoc = NULL;
> +    xmlXPathContextPtr ctxt = NULL;
> +    char *state = NULL;
> +    int external;
>       char *parent = NULL;
>       bool ret = false;
>       int count;
> @@ -839,18 +842,48 @@ cmdSnapshotInfo(vshControl *ctl, const vshCmd *cmd)
>       if (!doc)
>           goto cleanup;
>
> -    tmp = strstr(doc, "<state>");
> -    if (!tmp) {
> +    xmldoc = virXMLParseStringCtxt(doc, _("(domain_snapshot)"), &ctxt);
> +    if (!xmldoc)
> +        goto cleanup;
> +
> +    state = virXPathString("string(/domainsnapshot/state)", ctxt);
> +    if (!state) {
>           vshError(ctl, "%s",
>                    _("unexpected problem reading snapshot xml"));

We probably could be a bit more specific about the error here, but 
that's not really important.

>           goto cleanup;
>       }
> -    tmp += strlen("<state>");
> -    vshPrint(ctl, "%-15s %.*s\n", _("State:"),
> -             (int) (strchr(tmp, '<') - tmp), tmp);
> +    vshPrint(ctl, "%-15s %s\n", _("State:"), state);
> +
> +    /* In addition to state, location is useful.  If the snapshot has
> +     * a <memory> element, then the existence of snapshot='external'
> +     * prior to <domain> is the deciding factor; for snapshots
> +     * created prior to 1.0.1, a state of disk-only is the only
> +     * external snapshot.  */

This looks better than the raw xml magic.

ACK.

Peter