Path: utzoo!mnetor!uunet!husc6!bbn!mit-eddie!bloom-beacon!think!ames!oliveb!intelca!mipos3!cadev4!pinkas
From: pinkas@cadev4.intel.com (Israel Pinkas ~)
Newsgroups: comp.emacs
Subject: Re: Changing major mode in server mode
Message-ID: <1894@mipos3.intel.com>
Date: 18 Mar 88 23:57:41 GMT
References: <480@sol.warwick.ac.uk>
Sender: nobody@mipos3.intel.com
Reply-To: pinkas@cadev4.UUCP (Israel Pinkas ~)
Organization: Corporate CAD, INTeL Corporation, Santa Clara, CA
Lines: 195

In article <480@sol.warwick.ac.uk> cudcv@cu.warwick.ac.uk (Rob McMahon) writes:
><munch>
>
>I've just installed emacs 18.50, and have a couple of problems with M-x
>server-start/emacsclient.
>
>The first is more a comment than a problem.  In an NFS environment, you
>can't have a server running on more than one machine, because each uses
>the same rendezvous point, and each new invocation of the server removes
>the socket the other machine had created.  Maybe it should be using
>something like ("%s/.emacsclient.%s", getenv("HOME"), gethostname()) ?
>This isn't much of a problem for me, since I do most of the things I'd
>want a server for on the same machine.

I have this same problem.  I sent some mail to the GNU people about a year
ago, telling them what I had to do with GNU Emacs 17, but the changes never
made it into v18.  Anyway, here is the problem.

The NFS spec does not provide for special files to be accessed across NFS.
Thus, creating, reading, and writing a socket are not possible over NFS.
In our environment, we have a large number of workstations mounting
directories from a large VAX.  Almost all the users home directories are
mounted in this way.  This means that ~/.emacs_server is not feasible to
use unless emacs happens to be running on the file server, shich is not
desirable.

My solution was to change the three files that deal with the server/client.
They are: etc/emacsclient.c, etc/server.c, and lisp/server.el.  I changed
the name of the server file in each of these to /tmp/.emacs_server_<user>,
where <user> is the environment variable USER if available, the return
value of getuid() otherwise.

My reasoning is that the /tmp directory should be local.  (We run X on all
of our workstations, and X10 puts a socket file in /tmp.  I figured that if
/tmp is not local, we have bigger problems than emacs servers not running.)
Diskless nodes should be OK as they do not mount / via NFS.  (This is not
tested, though.)

Following are the diffs I put into 18.49.  When I get 18.50, I will look
into what problems might be caused on sysV (which I understand iis
supported, but we have some nodes running NFS also).

Note that you may still only have one emacs server per user per machine.
Thus, if you have a group account, and two users run emacs, the second one
to start the server will receive all subsequent requests.  Other things
might be messed up.  Since this was a limitation in the original code, I
don't mind this.  And I am wary.  The reason that I didn't do anything
about this is that I couldn't figure out how to make the clients know which
server to talk to.  A possibility for resolving this could be:

If under X, encode $DISPLAY in the server filename.  All clients on that
window would get the same server.  Since I don't anticipate two users on
the same window in the same account not being able to use the same emacs,
this should work.  Something similar could be done for Suns and other
windowing systems.

Otherwise, we must be running the server on the same terminal as the
client.  (I don't know what to do in the case of layers/emacs terminal
emulation.  Suggestions welcome.)  Place the name of the terminal in the
server filename.  For ptys (layers, terminal-mode) the terminal name of the
real terminal might be used.

-Israel

Cut here and make sure that Pnews did not add a .signature below

------------------------------------------------------------------
*** lisp/server.el.orig	Sun Feb 21 13:00:39 1988
--- lisp/server.el	Fri Mar 18 15:23:31 1988
***************
*** 108,114
        (progn
  	(set-process-sentinel server-process nil)
  	(condition-case () (delete-process server-process) (error nil))))
!   (condition-case () (delete-file "~/.emacs_server") (error nil))
    ;; If we already had a server, clear out associated status.
    (while server-clients
      (let ((buffer (nth 1 (car server-clients))))

--- 108,114 -----
        (progn
  	(set-process-sentinel server-process nil)
  	(condition-case () (delete-process server-process) (error nil))))
!   (condition-case () (delete-file "/tmp/.emacs_server_$USER") (error nil))
    ;; If we already had a server, clear out associated status.
    (while server-clients
      (let ((buffer (nth 1 (car server-clients))))
*** etc/server.c.orig	Thu Feb 25 10:56:33 1988
--- etc/server.c	Fri Mar 18 15:19:00 1988
***************
*** 55,61
  {
    int s, infd, fromlen;
    struct sockaddr_un server, fromunix;
!   char *homedir;
    char *str, string[BUFSIZ], code[BUFSIZ];
    FILE *infile;
    FILE **openfiles;

--- 55,61 -----
  {
    int s, infd, fromlen;
    struct sockaddr_un server, fromunix;
!   char *username;
    char *str, string[BUFSIZ], code[BUFSIZ];
    FILE *infile;
    FILE **openfiles;
***************
*** 78,90
        exit (1);
      }
    server.sun_family = AF_UNIX;
!   if ((homedir = getenv ("HOME")) == NULL)
!     {
!       fprintf (stderr,"No home directory\n");
!       exit (1);
!     }
!   strcpy (server.sun_path, homedir);
!   strcat (server.sun_path, "/.emacs_server");
    if (bind (s, &server, strlen (server.sun_path) + 2) < 0)
      {
        perror ("bind");

--- 78,87 -----
        exit (1);
      }
    server.sun_family = AF_UNIX;
!   if ((username = getenv ("USER")) == NULL)
!     sprintf(server.sun_path, "/tmp/.emacs_server_%d", getuid());
!   else
!     sprintf(server.sun_path, "/tmp/.emacs_server_%s", username);
    if (bind (s, &server, strlen (server.sun_path) + 2) < 0)
      {
        perror ("bind");
*** etc/emacsclient.c.orig	Fri Mar 18 15:06:56 1988
--- etc/emacsclient.c	Fri Mar 18 15:20:34 1988
***************
*** 48,54
    int s, n, i;
    FILE *out;
    struct sockaddr_un server;
!   char *homedir, *cwd, *str;
    char string[BUFSIZ];
  
    char *getenv (), *getwd ();

--- 48,54 -----
    int s, n, i;
    FILE *out;
    struct sockaddr_un server;
!   char *username, *cwd, *str;
    char string[BUFSIZ];
  
    char *getenv (), *getwd ();
***************
*** 69,81
        exit (1);
      }
    server.sun_family = AF_UNIX;
!   if ((homedir = getenv ("HOME")) == NULL)
!     {
!       fprintf (stderr, "No home directory\n");
!       exit (1);
!     }
!   strcpy (server.sun_path, homedir);
!   strcat (server.sun_path, "/.emacs_server");
    if (connect (s, &server, strlen (server.sun_path) + 2) < 0)
      {
        perror ("connect");

--- 69,78 -----
        exit (1);
      }
    server.sun_family = AF_UNIX;
!   if ((username = getenv ("USER")) == NULL)
!     sprintf(server.sun_path, "/tmp/.emacs_server_%d", getuid());
!   else
!     sprintf(server.sun_path, "/tmp/.emacs_server_%s", username);
    if (connect (s, &server, strlen (server.sun_path) + 2) < 0)
      {
        perror ("connect");

----------------------------------------------------------------------
Disclaimer: The above are my personal opinions, and in no way represent
the opinions of Intel Corporation.  In no way should the above be taken
to be a statement of Intel.

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