merge revision(s) 35474,35479,38939,38943,38963,38991,38994: [Backport #7786]

	* ext/socket/raddrinfo.c (init_unix_addrinfo): support the longest
	  path in sockaddr_un.
	  (inspect_sockaddr): ditto.
	  (addrinfo_mdump): ditto.
	  (addrinfo_mload): ditto.
	  (rsock_unixpath_str): new function.
	  (rsock_unixpath): removed.
	  (rsock_unixaddr): use rsock_unixpath_str.

	* ext/socket/socket.c (sock_s_pack_sockaddr_un): support the longest
	  path in sockaddr_un.
	  (sock_s_unpack_sockaddr_un): ditto.
	  (sock_s_gethostbyaddr): unused variable removed.

	* ext/socket/unixsocket.c (rsock_init_unixsock): support the longest
	  path in sockaddr_un.

	* ext/socket/rubysocket.h (rsock_unixpath_str): declared.
	  (rsock_unixpath): removed.

	* test/socket/test_unix.rb: comment out test_nul because abstract unix
	  sockets may contain NULs.

	* ext/socket/socket.c (sock_s_pack_sockaddr_un): support the longest
	  path in sockaddr_un, really.
	  reported by nagachika.
	  http://d.hatena.ne.jp/nagachika/20120426/ruby_trunk_changes_35474_35476

	* ext/socket/raddrinfo.c (rsock_unixpath_len, init_unix_addrinfo),
	  ext/socket/unixsocket.c (unixsock_connect_internal,
	  rsock_init_unixsock): calculate the correct address length of
	  an abstract socket.  Without this fix, sizeof(struct sockaddr_un)
	  is specified as the length of an abstract socket for bind(2) or
	  connect(2), so the address of the socket is filled with extra NUL
	  characters.  See unix(7) for details.

	* ext/socket/lib/socket.rb (unix_server_socket): don't access the
	  file system if the platform is Linux and path starts with NUL,
	  which means that the socket is an abstract socket.

	* test/socket/test_unix.rb: related test.

	* ext/socket/raddrinfo (rsock_unix_sockaddr_len): renamed from
	  rsock_unixpath_len, because it returns not the length of the path,
	  but the length of a socket address for the path.

	* ext/socket/socket.c (sock_s_pack_sockaddr_un): calculate the
	  correct address length of an abstract socket.

	* test/socket/test_unix.rb: related test.

	* ext/socket/unixsocket.c (rsock_init_unixsock): use rb_inspect()
	  because rb_sys_fail_str() fails if its argument contains NUL.

	* test/socket/test_unix.rb: related test.

	* ext/socket/raddrinfo.c (rsock_unix_sockaddr_len): return
	  sizeof(sa_familiy_t) if path is empty.  see "Autobind Feature" in
	  unix(7) for details.

	* ext/socket/lib/socket.rb (unix_socket_abstract_name?): treat an
	  empty path as an abstract name.

	* test/socket/test_unix.rb: related test.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@39096 b2dd03c8-39d4-4d8f-98ff-823fe69b080e