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Date: Tue, 17 Nov 2009 10:12:31 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] Don't leak file descriptors
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To: Jamie Lokier <jamie@shareable.org>
Cc: Blue Swirl <blauwirbel@gmail.com>, qemu-devel@nongnu.org

Am 17.11.2009 00:05, schrieb Jamie Lokier:
> Blue Swirl wrote:
>> On Mon, Nov 16, 2009 at 2:47 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>>> Am 13.11.2009 22:05, schrieb Blue Swirl:
>>>> On Fri, Nov 13, 2009 at 5:17 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>>>>> We're leaking file descriptors to child processes. Set FD_CLOEXEC on file
>>>>> descriptors that don't need to be passed to children to stop this misbehaviour.
>>>>
>>>>> -        c = accept(s, (struct sockaddr *)&addr, &addrlen);
>>>>> +        c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
>>>>
>>>> Would it be possible to improve the interface so that no casts are
>>>> needed for the calling code?
>>>
>>> How exactly would you do that? The only way I see to do it would be
>>> using void*, but I'm not sure if this really is an improvement.
>>
>> Instead of sockaddr_in vs. sockaddr and the lame casts in between, we
>> could have QSockAddr which magically works. Or if we only ever use
>> sockaddr_in, just use that.
> 
> int qemu_accept(int s, union __attribute__((__transparent_union__)) {
>                                struct sockaddr *sa;
>                                struct sockaddr_in *sin;
>                                struct sockaddr_in6 *sin6;
>                 } addr, socklen_t len);
> 
> #define qemu_accept(s, addr) qemu_accept(s, addr, sizeof(*addr))
> 
> Seems to work. :-)

Interesting. I didn't even know that __transparent_union__ exists. Might
be worth to consider, but the CLOEXEC patch definitely isn't the right
place to do the conversion.

Blue Swirl, care to do it on top of my patch?

Kevin