hyperv: Add a utility function for getting method output params

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 <jjongsma@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

diff --git a/src/hyperv/hyperv_wmi.c b/src/hyperv/hyperv_wmi.c
index 3e161429d59eabd703458c5fce39ecf7fab95b94..f0be0fa3fb583a7c00df069fbf568206920cc813 100644 (file)
--- a/src/hyperv/hyperv_wmi.c
+++ b/src/hyperv/hyperv_wmi.c
@@ -866,6 +866,140 @@ 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$s", job_id);
+        virBufferEscapeSQL(&query, "ASSOCIATORS OF {Msvm_ConcreteJob.InstanceID='%s'} ", job_id);
+        virBufferAsprintf(&query, "WHERE AssocClass = Msvm_AffectedJobElement ResultClass = %s",
+                          paramClassInfo->name);
+    } else {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Unexpected return code %1$d in method response"),
+                       return_code);
+        return -1;
+    }
+
+    return hypervGetWmiClassList(priv, paramClassInfo, &query, outParam);
+}
+
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  * Object
  */

diff --git a/src/hyperv/hyperv_wmi.h b/src/hyperv/hyperv_wmi.h
index 0560f83e0db0b17be6fa5210895658fb6f58feec..36ca85a5921a801756d48c4377bc1babb9dfcb77 100644 (file)
--- a/src/hyperv/hyperv_wmi.h
+++ b/src/hyperv/hyperv_wmi.h
@@ -166,6 +166,12 @@ int hypervInvokeMethod(hypervPrivate *priv,
                        hypervInvokeParamsList **paramsPtr,
                        WsXmlDocH *res);
 
+int hypervResponseGetOutputParam(hypervPrivate *priv,
+                                 WsXmlDocH response,
+                                 const char *paramName,
+                                 hypervWmiClassInfo *paramClassInfo,
+                                 hypervObject **outParam);
+
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  * CIM/Msvm_ReturnCode
  */