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@redhat.com>

FWIW: Very-much-appreciated-by: Kashyap Chamarthy <kchamart@redhat.com>

---

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