Re: [PATCH 05/20] qobject: Change qobject_to_json()'s value to GString

[Markus Armbruster]

Thomas Huth <thuth@redhat.com> writes:

> On 11/12/2020 18.11, Markus Armbruster wrote:
>> qobject_to_json() and qobject_to_json_pretty() build a GString, then
>> covert it to QString.  Just one of the callers actually needs a
>> QString: qemu_rbd_parse_filename().  A few others need a string they
>> can modify: qmp_send_response(), qga's send_response(), to_json_str(),
>> and qmp_fd_vsend_fds().  The remainder just need a string.
>> Change qobject_to_json() and qobject_to_json_pretty() to return the
>> GString.
>> qemu_rbd_parse_filename() now has to convert to QString.  All others
>> save a QString temporary.  to_json_str() actually becomes a bit
>> simpler, because GString provides more convenient modification
>> functions.
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>
>  Hi Markus!
>
> This patch broke the output of default values in the device help. With
> commit eab3a4678b07267c39e72:
>
> $ ./qemu-system-x86_64 -device pvpanic,help
> pvpanic options:
>   events=<uint8>         -  (default: (null))
>   ioport=<uint16>        -  (default: (null))
>   pvpanic[0]=<child<qemu:memory-region>>
>
> With the commit right before that one:
>
> $ ./qemu-system-x86_64 -device pvpanic,help
> pvpanic options:
>   events=<uint8>         -  (default: 3)
>   ioport=<uint16>        -  (default: 1285)
>   pvpanic[0]=<child<qemu:memory-region>>
>
> Any ideas how to fix that?

Yes:

diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
index c3324b0f86..bd8a947a63 100644
--- a/qom/object_interfaces.c
+++ b/qom/object_interfaces.c
@@ -159,7 +159,7 @@ char *object_property_help(const char *name, const char 
*type,
     }
     if (defval) {
         g_autofree char *def_json = g_string_free(qobject_to_json(defval),
-                                                  true);
+                                                  false);
         g_string_append_printf(str, " (default: %s)", def_json);
     }
 

I'll post a proper patch.  Sorry for the dumb mistake, and thanks for
pinpointing the commit!