qemu: monitor: Add monitor infrastructure for query-named-block-nodes

Add monitor tooling for calling query-named-block-nodes. The monitor
returns the data as the raw JSON array that is returned from the
monitor.

Unfortunately the logic to extract the node names for a complete backing
chain will be so complex that I won't be able to extract any meaningful
subset of the data in the monitor code.

src/qemu/qemu_monitor.c

@@ -4219,3 +4219,14 @@ qemuMonitorSetBlockThreshold(qemuMonitorPtr mon,
 
     return qemuMonitorJSONSetBlockThreshold(mon, nodename, threshold);
 }
+
+
+virJSONValuePtr
+qemuMonitorQueryNamedBlockNodes(qemuMonitorPtr mon)
+{
+    VIR_DEBUG("mon=%p", mon);
+
+    QEMU_CHECK_MONITOR_JSON_NULL(mon);
+
+    return qemuMonitorJSONQueryNamedBlockNodes(mon);
+}

src/qemu/qemu_monitor.h

@@ -1083,5 +1083,6 @@ int qemuMonitorSetBlockThreshold(qemuMonitorPtr mon,
                                  const char *nodename,
                                  unsigned long long threshold);
 
+virJSONValuePtr qemuMonitorQueryNamedBlockNodes(qemuMonitorPtr mon);
 
 #endif /* QEMU_MONITOR_H */

src/qemu/qemu_monitor_json.c

@@ -7557,3 +7557,29 @@ qemuMonitorJSONSetBlockThreshold(qemuMonitorPtr mon,
 
     return ret;
 }
+
+
+virJSONValuePtr
+qemuMonitorJSONQueryNamedBlockNodes(qemuMonitorPtr mon)
+{
+    virJSONValuePtr cmd;
+    virJSONValuePtr reply = NULL;
+    virJSONValuePtr ret = NULL;
+
+    if (!(cmd = qemuMonitorJSONMakeCommand("query-named-block-nodes", NULL)))
+        return NULL;
+
+    if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
+        goto cleanup;
+
+    if (qemuMonitorJSONCheckError(cmd, reply) < 0)
+        goto cleanup;
+
+    ret = virJSONValueObjectStealArray(reply, "return");
+
+ cleanup:
+    virJSONValueFree(cmd);
+    virJSONValueFree(reply);
+
+    return ret;
+}

src/qemu/qemu_monitor_json.h

@@ -518,4 +518,7 @@ int qemuMonitorJSONSetBlockThreshold(qemuMonitorPtr mon,
                                      unsigned long long threshold)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
+virJSONValuePtr qemuMonitorJSONQueryNamedBlockNodes(qemuMonitorPtr mon)
+    ATTRIBUTE_NONNULL(1);
+
 #endif /* QEMU_MONITOR_JSON_H */