[libvirt] [PATCH 2/4] snapshot: add 'virsh snapshot-info'

[Osier Yang]

On 2012年05月25日 11:33, Eric Blake wrote:
> Expose the recent API additions in virsh.  Borrows ideas from 'dominfo'
> for the general type of information to display.  Output looks like:
>
> $ tools/virsh snapshot-info fedora-local tmp
> Name:           tmp
> Domain:         fedora-local
> Current:        no
> State:          disk-snapshot
> Parent:         -
> Children:       1
> Descendants:    2
> Metadata:       yes
>
> possibly with fewer lines when talking to older servers.
>
> * tools/virsh.c (cmdSnapshotInfo): New command.
> * tools/virsh.pod (snapshot-info): Document it.
>
> ---
>   tools/virsh.c   |  125 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   tools/virsh.pod |    5 ++
>   2 files changed, 130 insertions(+), 0 deletions(-)
>
> diff --git a/tools/virsh.c b/tools/virsh.c
> index ffe6ed2..6a85338 100644
> --- a/tools/virsh.c
> +++ b/tools/virsh.c
> @@ -16601,6 +16601,129 @@ cleanup:
>   }
>
>   /*
> + * "snapshot-info" command
> + */
> +static const vshCmdInfo info_snapshot_info[] = {
> +    {"help", N_("snapshot information")},
> +    {"desc", N_("Returns basic information about a snapshot.")},
> +    {NULL, NULL}
> +};
> +
> +static const vshCmdOptDef opts_snapshot_info[] = {
> +    {"domain", VSH_OT_DATA, VSH_OFLAG_REQ, N_("domain name, id or uuid")},
> +    {"snapshotname", VSH_OT_DATA, 0, N_("snapshot name")},
> +    {"current", VSH_OT_BOOL, 0, N_("info on current snapshot")},
> +    {NULL, 0, 0, NULL}
> +};
> +
> +static bool
> +cmdSnapshotInfo(vshControl *ctl, const vshCmd *cmd)
> +{
> +    virDomainPtr dom;
> +    virDomainSnapshotPtr snapshot = NULL;
> +    const char *name;
> +    char *doc = NULL;
> +    char *tmp;
> +    char *parent = NULL;
> +    bool ret = false;
> +    int count;
> +    unsigned int flags;
> +    int current;
> +    int metadata;
> +
> +    if (!vshConnectionUsability(ctl, ctl->conn))
> +        return false;
> +
> +    dom = vshCommandOptDomain(ctl, cmd, NULL);
> +    if (dom == NULL)
> +        return false;
> +
> +    if (vshLookupSnapshot(ctl, cmd, "snapshotname", true, dom,
> +&snapshot,&name)<  0)
> +        goto cleanup;
> +
> +    vshPrint(ctl, "%-15s %s\n", _("Name:"), name);
> +    vshPrint(ctl, "%-15s %s\n", _("Domain:"), virDomainGetName(dom));
> +
> +    /* Determine if snapshot is current; this is useful enough that we
> +     * attempt a fallback.  */
> +    current = virDomainSnapshotIsCurrent(snapshot, 0);
> +    if (current<  0) {
> +        virDomainSnapshotPtr other = virDomainSnapshotCurrent(dom, 0);
> +
> +        virResetLastError();
> +        current = 0;
> +        if (other) {
> +            if (STREQ(name, virDomainSnapshotGetName(other)))
> +                current = 1;
> +            virDomainSnapshotFree(other);
> +        }
> +    }
> +    vshPrint(ctl, "%-15s %s\n", _("Current:"),
> +             current>  0 ? _("yes") : _("no"));
> +
> +    /* Get the XML configuration of the snapshot to determine the
> +     * state of the machine at the time of the snapshot.  */
> +    doc = virDomainSnapshotGetXMLDesc(snapshot, 0);
> +    if (!doc)
> +        goto cleanup;
> +
> +    tmp = strstr(doc, "<state>");
> +    if (!tmp) {
> +        vshError(ctl, "%s",
> +                 _("unexpected problem reading snapshot xml"));
> +        goto cleanup;
> +    }
> +    tmp += strlen("<state>");
> +    vshPrint(ctl, "%-15s %.*s\n", _("State:"),
> +             (int) (strchr(tmp, '<') - tmp), tmp);
> +
> +    if (vshGetSnapshotParent(ctl, snapshot,&parent)<  0)
> +        goto cleanup;
> +    vshPrint(ctl, "%-15s %s\n", _("Parent:"), parent ? parent : "-");
> +
> +    /* Children, Descendants.  After this point, the fallback to
> +     * compute children is too expensive, so we gracefully quit if the
> +     * APIs don't exist.  */
> +    if (ctl->useSnapshotOld) {
> +        ret = true;
> +        goto cleanup;
> +    }
> +    flags = 0;
> +    count = virDomainSnapshotNumChildren(snapshot, 0);
> +    if (count<  0)
> +        goto cleanup;
> +    vshPrint(ctl, "%-15s %d\n", _("Children:"), count);
> +    flags = VIR_DOMAIN_SNAPSHOT_LIST_DESCENDANTS;
> +    count = virDomainSnapshotNumChildren(snapshot, flags);
> +    if (count<  0)
> +        goto cleanup;
> +    vshPrint(ctl, "%-15s %d\n", _("Descendants:"), count);
> +
> +    /* Metadata; the fallback here relies on the fact that metadata
> +     * used to have an all-or-nothing effect on snapshot count.  */
> +    metadata = virDomainSnapshotHasMetadata(snapshot, 0);
> +    if (metadata<  0) {
> +        virResetLastError();
> +        count = virDomainSnapshotNum(dom,
> +                                     VIR_DOMAIN_SNAPSHOT_LIST_METADATA);
> +        metadata = count != 0;
> +    }
> +    vshPrint(ctl, "%-15s %s\n", _("Metadata:"),
> +             metadata>  0 ? _("yes") : _("no"));
> +
> +    ret = true;
> +
> +cleanup:
> +    VIR_FREE(doc);
> +    VIR_FREE(parent);
> +    if (snapshot)
> +        virDomainSnapshotFree(snapshot);
> +    virDomainFree(dom);
> +    return ret;
> +}
> +
> +/*
>    * "snapshot-list" command
>    */
>   static const vshCmdInfo info_snapshot_list[] = {
> @@ -17702,6 +17825,8 @@ static const vshCmdDef snapshotCmds[] = {
>        info_snapshot_dumpxml, 0},
>       {"snapshot-edit", cmdSnapshotEdit, opts_snapshot_edit,
>        info_snapshot_edit, 0},
> +    {"snapshot-info", cmdSnapshotInfo, opts_snapshot_info,
> +     info_snapshot_info, 0},
>       {"snapshot-list", cmdSnapshotList, opts_snapshot_list,
>        info_snapshot_list, 0},
>       {"snapshot-parent", cmdSnapshotParent, opts_snapshot_parent,
> diff --git a/tools/virsh.pod b/tools/virsh.pod
> index ef71717..6553825 100644
> --- a/tools/virsh.pod
> +++ b/tools/virsh.pod
> @@ -2504,6 +2504,11 @@ a snapshot name must be done with care, since the contents of some
>   snapshots, such as internal snapshots within a single qcow2 file, are
>   accessible only from the original name.
>
> +=item B<snapshot-info>  I<domain>  {I<snapshot>  | I<--current>}
> +
> +Output basic information about a named<snapshot>, or the current snapshot
> +with I<--current>.
> +
>   =item B<snapshot-list>  I<domain>  [{I<--parent>  | I<--roots>  | I<--tree>}]
>   [{[I<--from>] B<snapshot>  | I<--current>} [I<--descendants>]]
>   [I<--metadata>] [I<--leaves>]

ACK

Osier