Re: [Qemu-devel] [PATCH v2 06/15] set_property(): extend signature with Error

[Markus Armbruster]

Luiz Capitulino <address@hidden> writes:

> On Thu, 7 Feb 2013 15:18:41 -0200
> Eduardo Habkost <address@hidden> wrote:
>
>> On Tue, Feb 05, 2013 at 09:39:19PM +0100, Laszlo Ersek wrote:
>> > 
>> > Signed-off-by: Laszlo Ersek <address@hidden>
>> > ---
>> >  hw/qdev-monitor.c |   21 ++++++++++++++++-----
>> >  1 files changed, 16 insertions(+), 5 deletions(-)
>> > 
>> > diff --git a/hw/qdev-monitor.c b/hw/qdev-monitor.c
>> > index cf96046..545e66c 100644
>> > --- a/hw/qdev-monitor.c
>> > +++ b/hw/qdev-monitor.c
>> > @@ -100,9 +100,14 @@ static void qdev_print_devinfo(ObjectClass *klass, 
>> > void *opaque)
>> >      error_printf("\n");
>> >  }
>> >  
>> > +typedef struct {
>> > +    DeviceState *dev;
>> > +    Error **errp;
>> > +} PropertyContext;
>> > +
>> >  static int set_property(const char *name, const char *value, void *opaque)
>> >  {
>> > -    DeviceState *dev = opaque;
>> > +    PropertyContext *ctx = opaque;
>> >      Error *err = NULL;
>> >  
>> >      if (strcmp(name, "driver") == 0)
>> > @@ -110,7 +115,7 @@ static int set_property(const char *name, const char 
>> > *value, void *opaque)
>> >      if (strcmp(name, "bus") == 0)
>> >          return 0;
>> >  
>> > -    qdev_prop_parse(dev, name, value, &err);
>> > +    qdev_prop_parse(ctx->dev, name, value, &err);
>> >      if (error_is_set(&err)) {
>> >          qerror_report_err(err);
>> >          error_free(err);
>> > @@ -481,10 +486,16 @@ DeviceState *qdev_device_add(QemuOpts *opts)
>> >      if (id) {
>> >          qdev->id = id;
>> >      }
>> > -    if (qemu_opt_foreach(opts, set_property, qdev, 1) != 0) {
>> > -        qdev_free(qdev);
>> > -        return NULL;
>> > +
>> > +    {
>> > +        PropertyContext ctx = { .dev = qdev, .errp = NULL };
>> > +
>> > +        if (qemu_opt_foreach(opts, set_property, &ctx, 1) != 0) {
>> 
>> What about redefining qemu_opt_loopfunc to accept an Error parameter?
>> 
>> qemu_opt_foreach() is used in only 4 places in the whole QEMU code, and
>> it already has code to abort on error (but using the function return
>> value instead of an Error** paramater).
>
> He would have to convert the users too, which would be very welcome,
> but it's out of the scope of this series IMO (but would be fine as
> a first series to this work).

I'm fine with this patch as is.

I wouldn't add Error support to qemu_opt_foreach(), I'd replace it by a
more C-ish qemu_opt_next():

    for (opt = qemu_opt_next(NULL); opt; opt = qemu_opt_next(opt)) {
        set_property(qdev, qemu_opt_name(opt), qemu_opt_value(opt), &err);
        if (err) {
            ...
            break;
        }
    }

Higher-order functions are great in Lisp, but awkward in C.

>
>> 
>> 
>> 
>> > +            qdev_free(qdev);
>> > +            return NULL;
>> > +        }
>> >      }
>> > +
>> >      if (qdev->id) {
>> >          object_property_add_child(qdev_get_peripheral(), qdev->id,
>> >                                    OBJECT(qdev), NULL);
>> > -- 
>> > 1.7.1
>> > 
>> > 
>>