On Fri, Sep 17, 2021 at 03:34:56PM +0200, Peter Krempa wrote:
> Issuing simple QMP commands is pain as they need to be wrapped by the
> JSON wrapper:
>
> { "execute": "COMMAND" }
>
> and optionally also:
>
> { "execute": "COMMAND", "arguments":...}
>
> For simple commands without arguments we can add syntax sugar to virsh
> which allows simple usage of QMP and additionally prepares also for
> passing through of the 'arguments' section:
>
> virsh qemu-monitor-command $VM query-status
>
> is equivalent to
>
> virsh qemu-monitor-command $VM '{"execute":"query-status"}'
>
> and
>
> virsh qemu-monitor-command $VM query-named-block-nodes '{"flat":true}'
> or
> virsh qemu-monitor-command $VM query-named-block-nodes '"flat":true'
>
> is equivalent to
>
> virsh qemu-monitor-command $VM '{"execute":"query-named-block-nodes", "arguments":{"flat":true}}'
Very cool; thanks for this.
> Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
FWIW:
Very-much-appreciated-by: Kashyap Chamarthy <kchamart@xxxxxxxxxx>
> ---
>
> v2:
> - dropped the '--qmpwrap' option and do wrapping if we don't get a
> JSON object instead. Similarly for arguments.
>
> docs/manpages/virsh.rst | 16 ++++++-
> tools/virsh-domain.c | 98 ++++++++++++++++++++++++++++++++++++-----
> 2 files changed, 103 insertions(+), 11 deletions(-)
>
> diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
> index 350ded2026..b4d31bf884 100644
> --- a/docs/manpages/virsh.rst
> +++ b/docs/manpages/virsh.rst
> @@ -7772,7 +7772,21 @@ If more than one argument is provided for *command*, they are concatenated with
> a space in between before passing the single command to the monitor.
>
> Note that libvirt uses the QMP to talk to qemu so *command* must be valid JSON
> -in QMP format to work properly.
> +in QMP format to work properly. If *command* is not a JSON object libvirt tries
> +to wrap it as a JSON object to provide convenient interface such as the groups
> +of commands with identical handling:
> +
> +::
> +
> + # simple command
> + $ virsh qemu-monitor-command VM commandname
> + $ virsh qemu-monitor-command VM '{"execute":"commandname"}'
Do you want to give a proper example here? E.g. `query-kvm` or
`query-status`, or `query-block`?
> + # with arguments
> + $ virsh qemu-monitor-command VM commandname '"arg1":123' '"arg2":"test"'
> + $ virsh qemu-monitor-command VM commandname '{"arg1":123,"arg2":"test"}'
> + $ virsh qemu-monitor-command VM '{"execute":"commandname", "arguments":{"arg1":123,"arg2":"test"}}'
> +
>
> If *--pretty* is given the QMP reply is pretty-printed.
>
> diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
> index 70aa4167c2..659aa1a242 100644
> --- a/tools/virsh-domain.c
> +++ b/tools/virsh-domain.c
> @@ -9445,6 +9445,84 @@ static const vshCmdOptDef opts_qemu_monitor_command[] = {
> {.name = NULL}
> };
>
> +
> +static char *
> +cmdQemuMonitorCommandConcatCmd(vshControl *ctl,
> + const vshCmd *cmd,
> + const vshCmdOpt *opt)
> +{
> + g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER;
> +
> + while ((opt = vshCommandOptArgv(ctl, cmd, opt)))
> + virBufferAsprintf(&buf, "%s ", opt->data);
> +
> + virBufferTrim(&buf, " ");
> +
> + return virBufferContentAndReset(&buf);
> +}
> +
> +
> +static char *
> +cmdQemuMonitorCommandQMPWrap(vshControl *ctl,
> + const vshCmd *cmd)
> +{
> + g_autofree char *fullcmd = cmdQemuMonitorCommandConcatCmd(ctl, cmd, NULL);
> + g_autoptr(virJSONValue) fullcmdjson = virJSONValueFromString(fullcmd);
> + g_autofree char *fullargs = NULL;
> + g_autoptr(virJSONValue) fullargsjson = NULL;
> + const vshCmdOpt *opt = NULL;
> + const char *commandname = NULL;
> + g_autoptr(virJSONValue) command = NULL;
> + g_autoptr(virJSONValue) arguments = NULL;
> +
> + /* if we've got a JSON object, pass it through */
> + if (virJSONValueIsObject(fullcmdjson))
> + return g_steal_pointer(&fullcmd);
> +
> + /* we try to wrap the command and possible arguments into a JSON object, if
> + * we as fall back we pass through what we've got from the user */
> +
> + if ((opt = vshCommandOptArgv(ctl, cmd, opt)))
> + commandname = opt->data;
> +
> + /* now we process arguments similarly to how we've dealt with the full command */
> + if ((fullargs = cmdQemuMonitorCommandConcatCmd(ctl, cmd, opt)))
> + fullargsjson = virJSONValueFromString(fullargs);
> +
> + /* for empty args or a valid JSON object we just use that */
> + if (!fullargs || virJSONValueIsObject(fullargsjson)) {
> + arguments = g_steal_pointer(&fullargsjson);
> + } else {
> + /* for a non-object we try to concatenate individual _ARGV bits into a
> + * JSON object wrapper and try using that */
> + g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER;
> +
> + virBufferAddLit(&buf, "{");
> + /* opt points to the _ARGV option bit containing the command so we'll
> + * iterate through the arguments now */
> + while ((opt = vshCommandOptArgv(ctl, cmd, opt)))
> + virBufferAsprintf(&buf, "%s,", opt->data);
> +
> + virBufferTrim(&buf, ",");
> + virBufferAddLit(&buf, "}");
> +
> + if (!(arguments = virJSONValueFromString(virBufferCurrentContent(&buf)))) {
> + vshError(ctl, _("failed to wrap arguments '%s' into a QMP command wrapper"),
> + fullargs);
> + return NULL;
> + }
> + }
> +
> + if (virJSONValueObjectCreate(&command,
> + "s:execute", commandname,
> + "A:arguments", &arguments,
> + NULL) < 0)
> + return NULL;
> +
> + return virJSONValueToString(command, false);
> +}
> +
> +
> static bool
> cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd)
> {
> @@ -9453,8 +9531,6 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd)
> g_autofree char *result = NULL;
> g_autoptr(virJSONValue) resultjson = NULL;
> unsigned int flags = 0;
> - const vshCmdOpt *opt = NULL;
> - g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER;
> bool pretty = vshCommandOptBool(cmd, "pretty");
> bool returnval = vshCommandOptBool(cmd, "return-value");
> virJSONValue *formatjson;
> @@ -9466,15 +9542,17 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd)
> if (!(dom = virshCommandOptDomain(ctl, cmd, NULL)))
> return false;
>
> - while ((opt = vshCommandOptArgv(ctl, cmd, opt)))
> - virBufferAsprintf(&buf, "%s ", opt->data);
> -
> - virBufferTrim(&buf, " ");
> -
> - monitor_cmd = virBufferContentAndReset(&buf);
> -
> - if (vshCommandOptBool(cmd, "hmp"))
> + if (vshCommandOptBool(cmd, "hmp")) {
> flags |= VIR_DOMAIN_QEMU_MONITOR_COMMAND_HMP;
> + monitor_cmd = cmdQemuMonitorCommandConcatCmd(ctl, cmd, NULL);
> + } else {
> + monitor_cmd = cmdQemuMonitorCommandQMPWrap(ctl, cmd);
> + }
> +
> + if (!monitor_cmd) {
> + vshSaveLibvirtError();
> + return NULL;
> + }
>
> if (virDomainQemuMonitorCommand(dom, monitor_cmd, &result, flags) < 0)
> return false;
> --
> 2.31.1
>
--
/kashyap
