qom: qom_{get, set} monitor commands (v2)

This allows clients to read and write device model properties through QMP.  QAPI
doesn't support Visitor types yet and these commands are special in that they
don't work with fixed types.

I've added a documentation stub to qapi-schema.json so we can keep consistency
there.

Signed-off-by: Anthony Liguori <[email protected]>
diff --git a/qmp.c b/qmp.c
index 8e9a595..5e09b41 100644
--- a/qmp.c
+++ b/qmp.c
@@ -17,6 +17,8 @@
 #include "kvm.h"
 #include "arch_init.h"
 #include "hw/qdev.h"
+#include "qapi/qmp-input-visitor.h"
+#include "qapi/qmp-output-visitor.h"
 
 NameInfo *qmp_query_name(Error **errp)
 {
@@ -182,3 +184,66 @@
 
     return props;
 }
+
+/* FIXME: teach qapi about how to pass through Visitors */
+int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret)
+{
+    const char *path = qdict_get_str(qdict, "path");
+    const char *property = qdict_get_str(qdict, "property");
+    QObject *value = qdict_get(qdict, "value");
+    Error *local_err = NULL;
+    QmpInputVisitor *mi;
+    DeviceState *dev;
+
+    dev = qdev_resolve_path(path, NULL);
+    if (!dev) {
+        error_set(&local_err, QERR_DEVICE_NOT_FOUND, path);
+        goto out;
+    }
+
+    mi = qmp_input_visitor_new(value);
+    qdev_property_set(dev, qmp_input_get_visitor(mi), property, &local_err);
+
+    qmp_input_visitor_cleanup(mi);
+
+out:
+    if (local_err) {
+        qerror_report_err(local_err);
+        error_free(local_err);
+        return -1;
+    }
+
+    return 0;
+}
+
+int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret)
+{
+    const char *path = qdict_get_str(qdict, "path");
+    const char *property = qdict_get_str(qdict, "property");
+    Error *local_err = NULL;
+    QmpOutputVisitor *mo;
+    DeviceState *dev;
+
+    dev = qdev_resolve_path(path, NULL);
+    if (!dev) {
+        error_set(&local_err, QERR_DEVICE_NOT_FOUND, path);
+        goto out;
+    }
+
+    mo = qmp_output_visitor_new();
+    qdev_property_get(dev, qmp_output_get_visitor(mo), property, &local_err);
+    if (!local_err) {
+        *ret = qmp_output_get_qobject(mo);
+    }
+
+    qmp_output_visitor_cleanup(mo);
+
+out:
+    if (local_err) {
+        qerror_report_err(local_err);
+        error_free(local_err);
+        return -1;
+    }
+
+    return 0;
+}