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Date: Mon, 16 Nov 2009 23:05:07 +0000
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [Qemu-devel] [PATCH] Don't leak file descriptors
Message-ID: <20091116230507.GG12063@shareable.org>
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To: Blue Swirl <blauwirbel@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org

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. :-)

Or use a typedef to prettify, but there's no need for another named
type in the API.  (But you might create QSockAddr anyway, for things
like printing and parsing).

Enjoy,
-- Jamie