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From: Fam Zheng <famz@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Markus Armbruster <armbru@redhat.com>,
	QEMU Developers <qemu-devel@nongnu.org>,
	Anthony Liguori <aliguori@amazon.com>,
	Michael Roth <mdroth@linux.vnet.ibm.com>
Subject: Re: [Qemu-devel] qapi-commands.py generates code that uses uninitialized variables
Date: Fri, 11 Apr 2014 15:48:02 +0800	[thread overview]
Message-ID: <20140411074801.GA31773@T430.nay.redhat.com> (raw)
In-Reply-To: <CAFEAcA_SzS-Hj98x-OkrijJrTxLyO57jnHWwWt_NW=MS6wVQUA@mail.gmail.com>

On Fri, 04/11 08:27, Peter Maydell wrote:
> On 11 April 2014 02:40, Eric Blake <eblake@redhat.com> wrote:
> > We uncovered a real bug that would be fixed by this patch:
> > https://lists.gnu.org/archive/html/qemu-devel/2014-04/msg01745.html
> 
> No, that's a bug in the called code. The API here defines
> that for optional parameters, if the have_foo bool is false
> then the foo argument isn't set. The generated code
> can't know the correct default value (it just happens
> to be 0 in the case you point out, but what if the default
> speed were 100?) so this must be handled by the called
> code.
> 

Default value for a variable isn't default value for API logic, so apparently
called code must always handle both have_foo and foo. But there is a point to
take this patch from the language perspective, to avoid that an unset variable
is passed as a parameter from generated code.

Thanks,
Fam

  reply	other threads:[~2014-04-11  7:49 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-17 23:58 [Qemu-devel] qapi-commands.py generates code that uses uninitialized variables Peter Maydell
2014-03-18  9:32 ` Markus Armbruster
2014-03-20 19:21   ` Michael Roth
2014-03-26 14:34     ` Markus Armbruster
2014-03-28 14:19     ` Peter Maydell
2014-04-11  1:40       ` Eric Blake
2014-04-11  7:27         ` Peter Maydell
2014-04-11  7:48           ` Fam Zheng [this message]
2014-04-11 13:11           ` Eric Blake
2014-04-11 13:27             ` Peter Maydell
2014-04-11 14:01     ` Laszlo Ersek
2014-05-20 11:46     ` Peter Maydell

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