hmp: Implement qom-get HMP command

This started off as Andreas Färber's implementation from
March 2015, but after feedback from Paolo and Markus it morphed into
using the json output which handles structs reasonably.

Use with qom-list to find the members of an object.

(qemu) qom-get /backend/console[0]/device/vga.rom[0] size
65536
(qemu) qom-get /machine smm
"auto"
(qemu) qom-get /machine rtc-time
{
    "tm_year": 120,
    "tm_sec": 51,
    "tm_hour": 9,
    "tm_min": 50,
    "tm_mon": 4,
    "tm_mday": 20
}
(qemu) qom-get /machine frob
Error: Property '.frob' not found

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20200520151108.160598-2-dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/qom/qom-hmp-cmds.c b/qom/qom-hmp-cmds.c
index cd08233a4c..a8b0a080c7 100644
--- a/qom/qom-hmp-cmds.c
+++ b/qom/qom-hmp-cmds.c
@@ -12,6 +12,8 @@
 #include "qapi/error.h"
 #include "qapi/qapi-commands-qom.h"
 #include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qjson.h"
+#include "qapi/qmp/qstring.h"
 #include "qom/object.h"
 
 void hmp_qom_list(Monitor *mon, const QDict *qdict)
@@ -62,6 +64,22 @@ void hmp_qom_set(Monitor *mon, const QDict *qdict)
     hmp_handle_error(mon, err);
 }
 
+void hmp_qom_get(Monitor *mon, const QDict *qdict)
+{
+    const char *path = qdict_get_str(qdict, "path");
+    const char *property = qdict_get_str(qdict, "property");
+    Error *err = NULL;
+    QObject *obj = qmp_qom_get(path, property, &err);
+
+    if (err == NULL) {
+        QString *str = qobject_to_json_pretty(obj);
+        monitor_printf(mon, "%s\n", qstring_get_str(str));
+        qobject_unref(str);
+    }
+
+    hmp_handle_error(mon, err);
+}
+
 typedef struct QOMCompositionState {
     Monitor *mon;
     int indent;