Re: [PATCH 24/26] qom: introduce object_property_help()

["Marc-André Lureau" <marcandre.lureau@redhat.com>]

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Hi

On Fri, Mar 12, 2021 at 4:54 PM Thomas Huth <thuth@redhat.com> wrote:

> On 10/01/2020 16.30, Marc-André Lureau wrote:
> > Let's factor out the code to format a help string for a property. We
> > are going to reuse it in qdev next, which will bring some consistency.
> >
> > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> > ---
> >   include/qom/object.h    | 13 +++++++++++++
> >   qom/object_interfaces.c | 39 +++++++++++++++++++++++----------------
> >   2 files changed, 36 insertions(+), 16 deletions(-)
> >
> > diff --git a/include/qom/object.h b/include/qom/object.h
> > index 933e5c6cb9..a28e37a648 100644
> > --- a/include/qom/object.h
> > +++ b/include/qom/object.h
> > @@ -1854,6 +1854,19 @@ Object *container_get(Object *root, const char
> *path);
> >    */
> >   size_t object_type_get_instance_size(const char *typename);
> >
> > +/**
> > + * object_property_help:
> > + * @name: the name of the property
> > + * @type: the type of the property
> > + * @defval: the default value
> > + * @description: description of the property
> > + *
> > + * Returns: a user-friendly formatted string describing the property
> > + * for help purposes.
> > + */
> > +char *object_property_help(const char *name, const char *type,
> > +                           const char *defval, const char *description);
> > +
> >   G_DEFINE_AUTOPTR_CLEANUP_FUNC(Object, object_unref)
> >
> >   #endif
> > diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
> > index edb4cc4a3d..b7157d6ab0 100644
> > --- a/qom/object_interfaces.c
> > +++ b/qom/object_interfaces.c
> > @@ -158,6 +158,25 @@ int user_creatable_add_opts_foreach(void *opaque,
> QemuOpts *opts, Error **errp)
> >       return 0;
> >   }
> >
> > +char *object_property_help(const char *name, const char *type,
> > +                           const char *defval, const char *description)
> > +{
> > +    GString *str = g_string_new(NULL);
> > +
> > +    g_string_append_printf(str, "  %s=<%s>", name, type);
> > +    if (defval) {
> > +        g_string_append_printf(str, " (default: %s)", defval);
> > +    }
>
>   Hi!
>
> There is something weird going on wit the default value text...
>
> When I run:
>
> $ qemu-system-x86_64 -device isa-fdc,help
>
> I get:
>
> isa-fdc options:
>    bootindexA=<int32>
>    bootindexB=<int32>
>    dma=<uint32>           -  (default: (null))
>    driveA=<str>           - Node name or ID of a block device to use as a
> backend
>    driveB=<str>           - Node name or ID of a block device to use as a
> backend
>    fallback=<FdcDriveType> - FDC drive type, 144/288/120/none/auto
> (default: (null))
>    fdtypeA=<FdcDriveType> - FDC drive type, 144/288/120/none/auto
> (default: (null))
>    fdtypeB=<FdcDriveType> - FDC drive type, 144/288/120/none/auto
> (default: (null))
>    iobase=<uint32>        -  (default: (null))
>    irq=<uint32>           -  (default: (null))
>
> Why is it showing "(null)" as default values?
>

Congratulations, you found a regression! :)

QEMU emulator version 5.2.0 (qemu-5.2.0-6.fc33.1)
qemu-system-x86_64 -device isa-fdc,help
isa-fdc options:
  bootindexA=<int32>
  bootindexB=<int32>
  check_media_rate=<bool> - on/off (default: true)
  dma=<uint32>           -  (default: 2)
  driveA=<str>           - Node name or ID of a block device to use as a
backend
  driveB=<str>           - Node name or ID of a block device to use as a
backend
  fallback=<FdcDriveType> - FDC drive type, 144/288/120/none/auto (default:
"288")
  fdtypeA=<FdcDriveType> - FDC drive type, 144/288/120/none/auto (default:
"auto")
  fdtypeB=<FdcDriveType> - FDC drive type, 144/288/120/none/auto (default:
"auto")
  iobase=<uint32>        -  (default: 1008)
  irq=<uint32>           -  (default: 6)

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