AF_UNIX implementation for cygwin

[Chris Faylor]

This looks really cool.  Now I'm torn as to whether to put this into "B21"
or to wait until afterwards.

cgf

On Tue, Aug 03, 1999 at 10:18:44AM -0400, Sergey Okhapkin wrote:
>fhandler.cc        (fhandler_disk_file::fstat) check if the file is unix
>domain socket.
>                        (fhandler_disk_file::open) call set_socket_p().
>
>fhandler.h          (FH_LOCAL, FH_FIFO) new fhandler type flags.
>                        (fhandler_base) get/set_socket_p - new member
>functions.
>                        (fhandler_socket::addr_family) new member, not used
>now.
>                        (fhandler_socket::get/set_addr_family) new functions
>to access addr_family.
>
>include/sys/un.h new file.
>
>net.cc               include <sys/un.h>
>                        (cygwin_socket) alway create socket of AF_INET
>family, store argument's family.
>                        (get_inet_addr) new static function, does nothing
>for AF_INET, converts AF_UNIX requests
>                         into corresponding AF_INET requests.
>                        (cygwin_sendto) use get_inet_addr().
>                        (cygwin_connect) likewise.
>                        (cygwin_accept) check for sockaddr length.
>                        (cygwin_bind) if bind address is of AF_UNIX family,
>bind to any available port
>                         of loopback interface, store port number in the
>"socket file", set file attribute to S_IFSOCK.
>
>path.cc            (symlink_check_one) if the file begins with
>SOCKET_COOKIE, mark the file as PATH_SOCKET.
>
>path.h                (PATH_SOCKET) new enum value.
>                        (path_conv::issocket) new member function.
>                        (SOCKET_COOKIE) new define.
>
>syscalls.cc        (chmod) mark socket files with system file attribute.