[PATCH] Cygwin: allow opening an AF_LOCAL/AF_UNIX socket with O_PATH

[Corinna Vinschen]

On Jan 19 20:25, Ken Brown wrote:
> On 1/17/2020 4:51 AM, Corinna Vinschen wrote:
> > On Jan 17 10:48, Corinna Vinschen wrote:
> >> On Jan 16 18:34, Ken Brown wrote:
> >>> If that flag is not set, or if an attempt is made to open a different
> >>> type of socket, the errno is now EOPNOTSUPP instead of ENXIO.  This is
> >>> consistent with POSIX, starting with the 2016 edition.  Earlier
> >>> editions were silent on this issue.
> >>> ---
> >>>   winsup/cygwin/fhandler.h               |  2 ++
> >>>   winsup/cygwin/fhandler_socket.cc       |  2 +-
> >>>   winsup/cygwin/fhandler_socket_local.cc | 16 ++++++++++++++++
> >>>   winsup/cygwin/fhandler_socket_unix.cc  | 16 ++++++++++++++++
> >>>   winsup/cygwin/release/3.1.3            |  7 +++++++
> >>>   winsup/doc/new-features.xml            |  6 ++++++
> >>>   6 files changed, 48 insertions(+), 1 deletion(-)
> >>
> >> I'm a bit concerned here that some function calls might succeed
> >> accidentally or even crash, given that the original socket code doesn't
> >> cope with the nohandle flag.  Did you perform some basic testing?
> > 
> > Iow, do the usual socket calls on a fhandler_socket_local return EBADF
> > now?  Ignoring fhandler_socket_unix for now.
> 
> I really hadn't thought this through very well.  I think the following 
> additional patch should do the job:
> 
> --- a/winsup/cygwin/net.cc
> +++ b/winsup/cygwin/net.cc
> @@ -67,6 +67,11 @@ get (const int fd)
> 
>     if (!fh)
>       set_errno (ENOTSOCK);
> +  else if (fh->get_flags () & O_PATH)
> +    {
> +      set_errno (EBADF);
> +      fh = NULL;
> +    }
> 
>     return fh;
>   }

Looks like the easiest solution indeed.


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
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