* fhandler.cc (fhandler_base::get_proc_fd_name): Don't generate

"device:" entry.
	* fhandler.h (fhandler_socket::open): New method.
	(fhandler_pipe::open): New method.
	* fhandler_proc.cc (fhandler_proc::exists): Return -2 in case of
	/proc/self.
	* fhandler_process.cc (fhandler_process::exists): Return -2 in
	case of symlinks, -3 for pipes and -4 for sockets.
	(fhandler_process::fstat): Handle pipes and sockets.
	(fhandler_process::open): Handle opening /proc/<pid>/fd.
	(fhandler_process::fill_filebuf): Generate empty names for
	non exisiting file descriptors.
	* fhandler_socket.cc (fhandler_socket::get_proc_fd_name): Always
	generate "socket:[number]" strings as on Linux.
	(fhandler_socket::open): New method.
	(fhandler_socket::fstat): Always return socket type.
	* path.cc (symlink_info::set): Remove unused second parameter.
	(path_conv::check): Handle pipes and sockets in /proc.
	Set correct device type for AF_LOCAL sockets.
	* pinfo.cc (_pinfo::commune_recv): Generate empty names for
	non exisiting file descriptors.
	(_pinfo::fd): Ditto.
	* pipe.cc (fhandler_pipe::open): New method.

winsup/cygwin/pipe.cc

@@ -35,6 +35,13 @@ fhandler_pipe::fhandler_pipe ()
 {
 }
 
+int
+fhandler_pipe::open (int flags, mode_t mode)
+{
+  set_errno (ENXIO);
+  return 0;
+}
+
 _off64_t
 fhandler_pipe::lseek (_off64_t offset, int whence)
 {