On Fri, Apr 10, 2026 at 14:20:00 -0500, Jonathon Jongsma via Devel wrote:
> When invoking a method in WMI, it can either return synchronously or
> asynchronously (with return value 4096). In the latter case, the output
> parameters of the method are not present in the method response xml
> document. We have to fetch the output parameters via associations with
> the Job object that is returned in the method response.
>
> the hypervInvokeMethod() function already partially handles the async
> case by polling the job until it fails, completes successfully, or
> times out. This patch adds a utility function to fetch a named output
> parameter from a given method response xml document. It handles both
> synchronous and asynchronous cases.
>
> Signed-off-by: Jonathon Jongsma <[email protected]>
> ---
> src/hyperv/hyperv_wmi.c | 139 ++++++++++++++++++++++++++++++++++++++++
> src/hyperv/hyperv_wmi.h | 6 ++
> 2 files changed, 145 insertions(+)
>
> diff --git a/src/hyperv/hyperv_wmi.c b/src/hyperv/hyperv_wmi.c
> index 3e161429d5..1329d03262 100644
> --- a/src/hyperv/hyperv_wmi.c
> +++ b/src/hyperv/hyperv_wmi.c
> @@ -866,6 +866,145 @@ hypervInvokeMethod(hypervPrivate *priv,
> return 0;
> }
>
> +static char*
> +hypervOutputParamReferenceId(WsXmlNodeH node)
> +{
> + WsXmlNodeH selector_set = NULL;
> + WsXmlNodeH selector = NULL;
> + int i = 0;
> +
> + if (node)
> + selector_set = ws_xml_find_in_tree(node, XML_NS_WS_MAN,
> "SelectorSet", TRUE);
> +
> + if (selector_set) {
> + for (i = 0; (selector = ws_xml_get_child(selector_set, i,
> XML_NS_WS_MAN, "Selector")) != NULL; i++) {
> + if (STREQ_NULLABLE(ws_xml_find_attr_value(selector, NULL,
> "Name"), "InstanceID")) {
> + return ws_xml_get_node_text(selector);
> + }
> + }
> + }
> + return NULL;
> +}
> +
> +
> +/*
> + * hypervResponseGetOutputParam()
> + *
> + * Extracts an output parameter from a WMI method response and retrieves the
> + * referenced object.
> + *
> + * Handles both synchronous and asynchronous cases. When a method is
> + * synchronous, the parameter will be directly present in the response
> document.
> + * When the method returns asynchronously, we need to fetch the result
> parameter
> + * via its associations with the Msvm_ConcreteJob object referenced in the
> + * response document.
> + *
> + * Parameters:
> + * @priv: hypervPrivate object associated with the connection
> + * response: The WMI method response document
> + * paramName: The output parameter name (e.g., "ResultingSnapshot")
> + * paramClass: The WMI class info for the expected result type
> + * outParam: return location for the named output parameter
> + *
> + * Returns 0 on success, -1 on failure.
> + */
> +int
> +hypervResponseGetOutputParam(hypervPrivate *priv,
> + WsXmlDocH response,
> + const char *paramName,
> + hypervWmiClassInfo *paramClassInfo,
> + hypervObject **outParam)
> +{
> + g_auto(virBuffer) query = VIR_BUFFER_INITIALIZER;
> + WsXmlNodeH body = NULL;
> + WsXmlNodeH output_node = NULL;
> + char *output_name = NULL;
> + char *provider_ns = NULL;
> + const char *rv_str = NULL;
> + int return_code;
> + int i = 0;
> +
> + body = ws_xml_get_soap_body(response);
> + if (!body) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("Could not find SOAP Body in response"));
> + return -1;
> + }
> +
> + /* Find the $(METHOD)_OUTPUT node in the SOAP Body */
> + for (i = 0; (output_node = ws_xml_get_child(body, i, NULL, NULL)) !=
> NULL; i++) {
> + output_name = ws_xml_get_node_local_name(output_node);
> + if (output_name && g_str_has_suffix(output_name, "_OUTPUT"))
> + break;
> + output_node = NULL;
> + }
> +
> + if (!output_node) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("Could not find _OUTPUT node in method response"));
> + return -1;
> + }
> +
> + provider_ns = ws_xml_get_node_name_ns(output_node);
> +
> + rv_str = ws_xml_get_node_text(ws_xml_get_child(output_node, 0,
> provider_ns, "ReturnValue"));
> + if (!rv_str || virStrToLong_i(rv_str, NULL, 10, &return_code) < 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("Could not get ReturnValue from method response"));
> + return -1;
> + }
> +
> + if (return_code == CIM_RETURNCODE_COMPLETED_WITH_NO_ERROR) {
> + /* if this was a synchronous response, the output parameter should
> contain
> + * the id of an object, so we can simply look it up by its instance
> ID */
> + WsXmlNodeH param_node = ws_xml_get_child(output_node, 0,
> provider_ns, paramName);
> + const char *out_param_id = NULL;
> +
> + if (param_node)
> + out_param_id = hypervOutputParamReferenceId(param_node);
> +
> + if (!out_param_id) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("Could not find output parameter '%1$s' in
> response"),
> + paramName);
> + return -1;
> + }
> + VIR_DEBUG("Method response was synchronous: %1$s = %2$s", paramName,
> out_param_id);
> + virBufferAsprintf(&query, "SELECT * FROM %s ", paramClassInfo->name);
> + virBufferEscapeSQL(&query, "WHERE InstanceID='%s'", out_param_id);
> + } else if (return_code == CIM_RETURNCODE_TRANSITION_STARTED) {
> + /* if this was an asynchronous response, we have to get the output
> + * parameter from its association with the async job */
> + WsXmlNodeH job_node = ws_xml_get_child(output_node, 0, provider_ns,
> "Job");
> + const char *job_id = NULL;
> +
> + if (job_node)
> + job_id = hypervOutputParamReferenceId(job_node);
> +
> + if (!job_id) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("Could not find Job ID in async method
> response"));
> + return -1;
> + }
> + VIR_DEBUG("Method response was asynchronous. Job ID = %1$s", job_id);
> + virBufferEscapeSQL(&query,
> + "ASSOCIATORS OF {Msvm_ConcreteJob.InstanceID='%s'} ",
> + job_id);
> + virBufferAsprintf(&query,
> + "WHERE AssocClass = Msvm_AffectedJobElement "
> + "ResultClass = %s",
> + paramClassInfo->name);
These don't need this weird alignment at all.
> + } else {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("Unexpected return code %1$d in method response"),
> + return_code);
> + return -1;
> + }
> +
> + hypervGetWmiClassList(priv, paramClassInfo, &query, outParam);
No error handling? Didn't you want to do a return hypervGet..? here?
> + return 0;
> +}
Reviewed-by: Peter Krempa <[email protected]>
