Re: proposal: module 'accept4'

[Eric Blake]

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According to Bruno Haible on 8/22/2009 3:39 PM:
> Hi,
> 
> Here's the proposed module for function 'accept4'.
> 
> It does not define the macro SOCK_CLOEXEC. I think this macro should be
> replaced by a separate module, that would then also influence socket(),
> socketpair() - and what about connect()?

socket and socketpair both (need to) honor SOCK_CLOEXEC; but connect does
not create a new fd (it just modifies an existing one) so it doesn't need
any change.

>       nfd = _open_osfhandle ((long) new_handle,
>                            O_NOINHERIT | (flags & (O_TEXT | O_BINARY)));
>       if (nfd < 0)
>       {
>         int saved_errno = errno;
>         close (fd);
>         errno = saved_errno;
>         return -1;
>       }
> 
>       close (fd);
>       return nfd;

This means that nfd > fd, so there is a gap in the fd sequence which is
unexpected per POSIX rules.  Is it worth the hassle of using
dup2(nfd,fd),close(fd) instead of close(fd)?
>   if (flags & SOCK_CLOEXEC)
>     {
>       int fcntl_flags;
> 
>       if ((fcntl_flags = fcntl (fd, F_GETFD, 0)) < 0
>         || fcntl (fd, F_SETFD, fcntl_flags | FD_CLOEXEC) < 0)

Success for F_SETFD is like F_SETFL - you must compare against explicit -1.

Otherwise, looks sane to me.  Do you have a test case in mind?

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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