[Qemu-devel] [PATCH v4 5/5] object: Add 'help' option for all available backends and properties

[Lin Ma <lma@suse.com>]

'-object help' prints available user creatable backends.
'-object $typename,help' prints relevant properties.

Signed-off-by: Lin Ma <lma@suse.com>
---
 include/qom/object_interfaces.h |  2 ++
 qemu-options.hx                 |  7 +++++-
 qom/object_interfaces.c         | 55 +++++++++++++++++++++++++++++++++++++++++
 vl.c                            |  5 ++++
 4 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/include/qom/object_interfaces.h b/include/qom/object_interfaces.h
index 8b17f4d..197cd5f 100644
--- a/include/qom/object_interfaces.h
+++ b/include/qom/object_interfaces.h
@@ -165,4 +165,6 @@ int user_creatable_add_opts_foreach(void *opaque,
  */
 void user_creatable_del(const char *id, Error **errp);
 
+int user_creatable_help_func(void *opaque, QemuOpts *opts, Error **errp);
+
 #endif
diff --git a/qemu-options.hx b/qemu-options.hx
index b1fbdb0..b9573ce 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3761,7 +3761,9 @@ DEF("object", HAS_ARG, QEMU_OPTION_object,
     "                create a new object of type TYPENAME setting properties\n"
     "                in the order they are specified.  Note that the 'id'\n"
     "                property must be set.  These objects are placed in the\n"
-    "                '/objects' path.\n",
+    "                '/objects' path.\n"
+    "                Use '-object help' to print available backend types and\n"
+    "                '-object typename,help' to print relevant properties.\n",
     QEMU_ARCH_ALL)
 STEXI
 @item -object @var{typename}[,@var{prop1}=@var{value1},...]
@@ -3771,6 +3773,9 @@ in the order they are specified.  Note that the 'id'
 property must be set.  These objects are placed in the
 '/objects' path.
 
+Use @code{-object help} to print available backend types and
+@code{-object @var{typename},help} to print relevant properties.
+
 @table @option
 
 @item -object memory-backend-file,id=@var{id},size=@var{size},mem-path=@var{dir},share=@var{on|off}
diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
index bf59846..da8be39 100644
--- a/qom/object_interfaces.c
+++ b/qom/object_interfaces.c
@@ -5,6 +5,7 @@
 #include "qapi-visit.h"
 #include "qapi/qmp-output-visitor.h"
 #include "qapi/opts-visitor.h"
+#include "qemu/help_option.h"
 
 void user_creatable_complete(Object *obj, Error **errp)
 {
@@ -212,6 +213,60 @@ void user_creatable_del(const char *id, Error **errp)
     object_unparent(obj);
 }
 
+int user_creatable_help_func(void *opaque, QemuOpts *opts, Error **errp)
+{
+    const char *type = NULL;
+    Object *obj = NULL;
+    ObjectClass *klass;
+    ObjectProperty *prop;
+    ObjectPropertyIterator iter;
+
+    type = qemu_opt_get(opts, "qom-type");
+    if (type && is_help_option(type)) {
+        GSList *list;
+        printf("Available object backend types:\n");
+        for (list = object_class_get_list(TYPE_USER_CREATABLE, false);  \
+                list;                                                   \
+                list = list->next) {
+            const char *name;
+            name = object_class_get_name(OBJECT_CLASS(list->data));
+            if (strcmp(name, TYPE_USER_CREATABLE)) {
+                printf("%s\n", name);
+            }
+        }
+        g_slist_free(list);
+        goto out;
+    }
+
+    if (!type || !qemu_opt_has_help_opt(opts)) {
+        return 0;
+    }
+
+    klass = object_class_by_name(type);
+    if (!klass) {
+        printf("invalid object type: %s\n", type);
+        goto out;
+    }
+    if (object_class_is_abstract(klass)) {
+        printf("object type '%s' is abstract\n", type);
+        goto out;
+    }
+    obj = object_new(type);
+    object_property_iter_init(&iter, obj);
+
+    while ((prop = object_property_iter_next(&iter))) {
+        if (prop->description) {
+            printf("%s (%s, %s)\n", prop->name, prop->type, prop->description);
+        } else {
+            printf("%s (%s)\n", prop->name, prop->type);
+        }
+    }
+
+out:
+    object_unref(obj);
+    return 1;
+}
+
 static void register_types(void)
 {
     static const TypeInfo uc_interface_info = {
diff --git a/vl.c b/vl.c
index ebd47af..1456eca 100644
--- a/vl.c
+++ b/vl.c
@@ -4100,6 +4100,11 @@ int main(int argc, char **argv, char **envp)
         exit(0);
     }
 
+    if (qemu_opts_foreach(qemu_find_opts("object"), user_creatable_help_func,
+                          NULL, NULL)) {
+        exit(1);
+    }
+
     if (!trace_init_backends()) {
         exit(1);
     }
-- 
2.9.2