On 09/15/2017 04:35 PM, John Snow wrote: > > > On 08/04/2017 06:26 AM, Mao Zhongyi wrote: >> Replace init with realize in IDEDeviceClass, which has errp >> as a parameter. So all the implementations now use error_setg >> instead of error_report for reporting error. >>
>> @@ -2398,7 +2399,7 @@ int ide_init_drive(IDEState *s, BlockBackend *blk,
>> IDEDriveKind kind,
>> const char *version, const char *serial, const char
>> *model,
>> uint64_t wwn,
>> uint32_t cylinders, uint32_t heads, uint32_t secs,
>> - int chs_trans)
>> + int chs_trans, Error **errp)
>
> this function now requires an additional invariant, which is that we
> must return -1 AND set errp. Probably wisest to just get rid of the
> return code so that we don't accidentally goof this up in the future.
>
> I think Markus has had some guidance on this in the past, but admittedly
> I can't remember his preference.
Returning void requires callers to use boilerplate:
bar(..., Error **errp)
{
Error *err = NULL;
foo(..., &err);
if (err) {
error_propagate(errp, err);
handle error ...;
return;
}
}
whereas keeping the invariant that a -1 return is synonymous with err
being set is simpler:
bar(..., Error **errp)
{
if (foo(..., errp) < 0) {
handle error ...;
return;
}
}
So these days, the preference is to KEEP the redundancy rather than
eliminate it, due to ease-of-use concerns.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
signature.asc
Description: OpenPGP digital signature
