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Re: struct msghdr in socket.h is wrong
On Oct 17 10:44, Corinna Vinschen wrote:
> On Oct 15 22:23, Sam Steingold wrote:
> > > * Corinna Vinschen [2005-10-12 22:42:34 +0200]:
> > > On Oct 12 15:17, Sam Steingold wrote:
> > >> cyswin/socket.h:
> > >>
> > >> struct msghdr
> > >> {
> > >> void * msg_name; /* Socket name */
> > >> int msg_namelen; /* Length of name */
> > >> struct iovec * msg_iov; /* Data blocks */
> > >> int msg_iovlen; /* Number of blocks */
> > >> void * msg_accrights; /* Per protocol magic (eg BSD file descriptor passing) */
> > >> int msg_accrightslen; /* Length of rights list */
> > >> };
> > >
> > > This is the so called "older" implementation of struct msghdr as
> > > defined up to 4.2BSD. Since it's quite useless so far and since
> >
> > I am not sure I quite understand what you mean by useless.
> > is cygwin implementation somehow deficient?
> >
> sendmsg and recvmsg don't utilize the msg_accrights/msg_accrightslen member.
>
> > > applications using this structure should accomodate the old
> > > implementation anyway, I don't see a good reason to change this right
> > > now.
> >
> > the only reason applications have to accommodate the old implementation
> > is that some unixes still stick with it.
>
> So, from a portability perspective...
>
> > if you switch to the posix msghdr, I, for one, would not have to
> > accomodate the old implementation.
>
> I won't change it now. I'll change it at one point when there's some
> functionality.
Never mind, I've changed it in CVS. Note that msg_control, msg_controllen
and msg_flags members are still without function. However, msg_controllen
and msg_flags are both set to 0 on return from recvmsg. The CMSG_FIRSTHDR
macro is meant to handle this gracefully, so please try the next Cygwin
snapshot and report back. Keep in mind that for testing this correctly,
you have to install at least /usr/include/cygwin/socket.h and
/usr/lib/libcygwin.a additionally to the DLL.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
Red Hat, Inc.
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