New session management patch.

[Jan D.]

Kim F. Storm wrote:
> Another problem is how to restore things after restarting emacs.  I
> don't think you can rely on a hook to do this.  Some things may not
> have been added to the restore-hook when you run it (e.g. if gnus
> stores its state in a file, there need to be a gnus-restore-session
> function in the hook list for this to work.)
> 
> One possible fix would be to let the save-hook functions insert lisp
> code in the session save file which - when emacs restarts - is eval'ed
> to restore the previous state.
> 
> You should make a default choice of how the session file is named
> based on the session-id (define a function emacs-session-save-filename
> in x-win.el which the user can rewrite), and then -- at the place
> where you now do
...

I have incorporated your ideas almost verbatim,  Your remark about the
problem of restore is well put.  Also a default filename makes it
easier for functions to save state.

But I haven't made variables for functions emacs-session-save and
emacs-session-restore.  I figured that anyone can redefine the
functions if they so wish.

Another thing is that I had to make a PATH search for emacs to find
the absolute path for the emacs exeutable.  In the path search
and also in some lisp code that makes the filename, the directory
separator "/" is hard coded.

Is this OK?  Is there a variable to look at instead?  I found
directory-sep-char but it is deprecated.  I know VMS for instance
has X, but does it have SM and ICE also?

This patch still doesn't save any state, but it is getting closer.

        Jan D.


Index: lisp/term/x-win.el
--- lisp/term/x-win.el.orig     Thu Jan 24 20:20:12 2002
+++ lisp/term/x-win.el  Tue Feb 26 22:48:49 2002
@@ -234,6 +234,72 @@
            (funcall handler this-switch))
        (setq args (cons orig-this-switch args)))))
   (nconc (nreverse args) x-invocation-args))
+
+;; Handle the --smid switch.  This is used by the session manager
+;; to give us back our session id we had on the previous run.
+(defun x-handle-smid (switch)
+  (or (consp x-invocation-args)
+      (error "%s: missing argument to `%s' option" (invocation-name) switch))
+  (setq x-session-previous-id (car x-invocation-args)
+       x-invocation-args (cdr x-invocation-args)))
+
+(defvar emacs-save-session-functions nil
+  "Functions to run when a save-session event occurs.
+The functions does not get any argument.
+Functions can return non-nil to inform the session manager that the
+window system shutdown should be aborted.
+
+See also `emacs-session-save'.")
+
+(defun emacs-session-filename (session-id)
+  "Construct a filename to save the session in based on SESSION-ID.
+If the directory ~/.emacs.d exists, we make a filename in there, otherwise
+a file in the home directory."
+  (let ((basename (concat "emacs." session-id))
+       (emacs-dir "~/.emacs.d/"))
+    (expand-file-name (if (file-directory-p emacs-dir)
+                         (concat emacs-dir basename)
+                       (concat "~/." basename)))))
+       
+    (defun emacs-session-save ()
+  "Run the `emacs-save-session-functions' when window system is closing.
+When a session manager tells Emacs that the window system is shutting
+down, this function is called.  It calls the functions in the hook
+`emacs-save-session-functions'.  Functions are called with the current
+buffer set to a temporary buffer.  Functions should use `insert' to insert
+lisp code to save the session state.  The buffer is saved
+in a file in the home directory of the user running Emacs.  The file
+is evaluated when Emacs is restarted by the session manager.
+
+If any of the functions returns non-nil, no more functions are called
+and this function returns non-nil.  This will inform the session manager
+that it should abort the window system shutdown."
+  (let ((filename (emacs-session-filename x-session-id))
+       (buf (get-buffer-create (concat " *SES " x-session-id))))
+    (when (file-exists-p filename)
+      (delete-file filename))
+    (with-current-buffer buf
+      (let ((cancel-shutdown (condition-case nil
+                                (run-hook-with-args-until-success 
+                                 'emacs-save-session-functions x-session-id)
+                              (error t))))
+       (unless cancel-shutdown
+         (write-file filename))
+       (kill-buffer buf)
+       cancel-shutdown))))
+
+(defun emacs-session-restore ()
+  "Restore the Emacs session if started by a session manager.
+The file saved by `emacs-session-save' is evaluated and deleted if it
+exists."
+  (let ((filename (emacs-session-filename x-session-previous-id)))
+    (when (file-exists-p filename)
+      (load-file filename)
+      (delete-file filename)
+      (message "Restored session data"))))
+
+ 
+  
 
 ;;
 ;; Standard X cursor shapes, courtesy of Mr. Fox, who wanted ALL of them.
Index: lisp/startup.el
--- lisp/startup.el.orig        Wed Feb  6 15:59:10 2002
+++ lisp/startup.el     Tue Feb 26 22:48:49 2002
@@ -236,7 +236,8 @@
     ("--cursor-color" 1 x-handle-switch cursor-color)
     ("--vertical-scroll-bars" 0 x-handle-switch vertical-scroll-bars t)
     ("--line-spacing" 1 x-handle-numeric-switch line-spacing)
-    ("--border-color" 1 x-handle-switch border-width))
+    ("--border-color" 1 x-handle-switch border-width)
+    ("--smid" 1 x-handle-smid))
   "Alist of X Windows options.
 Each element has the form
   (NAME NUMARGS HANDLER FRAME-PARAM VALUE)
@@ -1028,7 +1029,12 @@
   (command-line-1 (cdr command-line-args))
 
   ;; If -batch, terminate after processing the command options.
-  (if noninteractive (kill-emacs t)))
+  (if noninteractive (kill-emacs t))
+
+  ;; Run emacs-session-restore (session management) if started by
+  ;; the session manager and we have a session manager connection.
+  (if (and (stringp x-session-previous-id) (stringp x-session-id))
+      (emacs-session-restore)))
 
 (defcustom initial-scratch-message (purecopy "\
 ;; This buffer is for notes you don't want to save, and for Lisp evaluation.
Index: src/Makefile.in
--- src/Makefile.in.orig        Tue Feb 26 22:44:10 2002
+++ src/Makefile.in     Tue Feb 26 22:48:49 2002
@@ -294,7 +294,7 @@
 #ifdef HAVE_MENUS
 
 /* Include xmenu.o in the list of X object files.  */
-XOBJ= xterm.o xfns.o xselect.o xrdb.o fontset.o
+XOBJ= xterm.o xfns.o xselect.o xrdb.o fontset.o xsmfns.o
 
 /* The X Menu stuff is present in the X10 distribution, but missing
    from X11.  If we have X10, just use the installed library;
@@ -315,7 +315,7 @@
 
 /* Otherwise, omit xmenu.o from the list of X object files, and
    don't worry about the menu library at all.  */
-XOBJ= xterm.o xfns.o xselect.o xrdb.o fontset.o
+XOBJ= xterm.o xfns.o xselect.o xrdb.o fontset.o xsmfns.o
 LIBXMENU=
 #endif /* not HAVE_MENUS */
 
@@ -366,7 +366,11 @@
 #endif /* not LIBXT_STATIC */
 
 #else /* not USE_X_TOOLKIT */
+#ifdef HAVE_X_SM
+LIBXT=-lSM -lICE
+#else
 LIBXT=
+#endif
 #endif /* not USE_X_TOOLKIT */
 
 #if HAVE_XPM
@@ -549,7 +553,7 @@
    These go in the DOC file on all machines
    in case they are needed there.  */
 SOME_MACHINE_OBJECTS = sunfns.o dosfns.o msdos.o \
-  xterm.o xfns.o xmenu.o xselect.o xrdb.o
+  xterm.o xfns.o xmenu.o xselect.o xrdb.o xsmfns.o
 
 
 #ifdef TERMINFO
@@ -1128,6 +1132,7 @@
 xselect.o: xselect.c dispextern.h frame.h xterm.h blockinput.h charset.h \
   coding.h ccl.h buffer.h atimer.h systime.h $(config_h)
 xrdb.o: xrdb.c $(config_h) epaths.h
+xsmfns.o: xsmfns.c $(config_h) systime.h sysselect.h lisp.h termhooks.h
 hftctl.o: hftctl.c $(config_h)
 sound.o: sound.c dispextern.h $(config_h)
 atimer.o: atimer.c atimer.h systime.h $(config_h)
Index: src/xterm.c
--- src/xterm.c.orig    Tue Feb 26 22:44:13 2002
+++ src/xterm.c Tue Feb 26 22:48:49 2002
@@ -10032,6 +10032,12 @@
          x_io_error_quitter (dpyinfo->display);
        }
 
+#ifdef HAVE_X_SM
+      BLOCK_INPUT;
+      count += x_session_check_input (bufp, &numchars);
+      UNBLOCK_INPUT;
+#endif
+
       while (XPending (dpyinfo->display))
        {
          XNextEvent (dpyinfo->display, &event);
@@ -10114,11 +10120,17 @@
                           the session manager, who's looking for such a
                           PropertyNotify.  Can restart processing when
                           a keyboard or mouse event arrives.  */
-                       if (numchars > 0)
+                        /* If we have a session manager, don't set this.
+                           KDE will then start two Emacsen, one for the
+                           session manager and one for this. */
+                       if (numchars > 0
+#ifdef HAVE_X_SM
+                            && ! x_session_have_connection ()
+#endif
+                            )
                          {
                            f = x_top_window_to_frame (dpyinfo,
                                                       event.xclient.window);
-
                            /* This is just so we only give real data once
                               for a single Emacs process.  */
                            if (f == SELECTED_FRAME ())
@@ -15046,6 +15058,10 @@
 #endif /* ! defined (SIGWINCH) */
 
   signal (SIGPIPE, x_connection_signal);
+
+#ifdef HAVE_X_SM
+  x_session_initialize ();
+#endif
 }
 
 
Index: src/xterm.h
--- src/xterm.h.orig    Tue Feb 26 22:44:13 2002
+++ src/xterm.h Tue Feb 26 22:48:49 2002
@@ -1098,3 +1098,11 @@
 #ifdef USE_X_TOOLKIT
 extern void widget_store_internal_border P_ ((Widget));
 #endif
+
+/* Defined in xsmfns.c */
+#ifdef HAVE_X_SM
+extern void x_session_initialize P_ ((void));
+extern int x_session_check_input P_ ((struct input_event *bufp,
+                                      int *numchars));
+extern int x_session_have_connection P_ ((void));
+#endif
Index: src/termhooks.h
--- src/termhooks.h.orig        Sat Oct 20 07:51:38 2001
+++ src/termhooks.h     Tue Feb 26 22:48:49 2002
@@ -323,7 +323,11 @@
 
   /* Queued from XTread_socket on FocusIn events.  Translated into
      `switch-frame' events in kbd_buffer_get_event, if necessary.  */
-  FOCUS_IN_EVENT
+  FOCUS_IN_EVENT,
+
+  /* Queued from XTread_socket when session manager sends
+     save yourself before shutdown. */
+  save_session_event
 };
 
 /* If a struct input_event has a kind which is selection_request_event
Index: src/keyboard.c
--- src/keyboard.c.orig Tue Feb 26 22:44:10 2002
+++ src/keyboard.c      Tue Feb 26 22:48:49 2002
@@ -554,6 +554,8 @@
 Lisp_Object Qlanguage_change;
 #endif
 Lisp_Object Qdrag_n_drop;
+Lisp_Object Qsave_session;
+
 /* Lisp_Object Qmouse_movement; - also an event header */
 
 /* Properties of event headers.  */
@@ -3725,6 +3727,11 @@
          kbd_fetch_ptr = event + 1;
        }
 #endif
+      else if (event->kind == save_session_event)
+        {
+          obj = Fcons (Qsave_session, Qnil);
+         kbd_fetch_ptr = event + 1;
+        }
       /* Just discard these, by returning nil.
         With MULTI_KBOARD, these events are used as placeholders
         when we need to randomly delete events from the queue.
@@ -5389,6 +5396,9 @@
       /* A user signal.  */
       return *lispy_user_signals[event->code];
       
+    case save_session_event:
+      return Qsave_session;
+      
       /* The 'kind' field of the event is something we don't recognize.  */
     default:
       abort ();
@@ -10351,6 +10361,9 @@
   Qdrag_n_drop = intern ("drag-n-drop");
   staticpro (&Qdrag_n_drop);
 
+  Qsave_session = intern ("save-session");
+  staticpro(&Qsave_session);
+  
   Qusr1_signal = intern ("usr1-signal");
   staticpro (&Qusr1_signal);
   Qusr2_signal = intern ("usr2-signal");
@@ -10935,4 +10948,6 @@
                            "ignore-event");
   initial_define_lispy_key (Vspecial_event_map, "make-frame-visible",
                            "ignore-event");
+  initial_define_lispy_key (Vspecial_event_map, "save-session",
+                           "handle-save-session");
 }
Index: src/lisp.h
--- src/lisp.h.orig     Thu Feb  7 21:22:19 2002
+++ src/lisp.h  Tue Feb 26 22:48:49 2002
@@ -3040,6 +3040,9 @@
 EXFUN (Fx_file_dialog, 4);
 #endif /* HAVE_X_WINDOWS */
 
+/* Defined in xsmfns.c */
+extern void syms_of_xsmfns P_ ((void));
+
 /* Defined in xselect.c */
 extern void syms_of_xselect P_ ((void));
 
Index: src/emacs.c
--- src/emacs.c.orig    Mon Jan 14 14:47:56 2002
+++ src/emacs.c Tue Feb 26 22:48:49 2002
@@ -1464,6 +1464,7 @@
       syms_of_xterm ();
       syms_of_xfns ();
       syms_of_fontset ();
+      syms_of_xsmfns ();
 #ifdef HAVE_X11
       syms_of_xselect ();
 #endif
Index: src/config.in
--- src/config.in.orig  Fri Dec 28 20:06:08 2001
+++ src/config.in       Tue Feb 26 22:48:49 2002
@@ -92,6 +92,9 @@
 /* Define if we should use XIM, if it is available.  */
 #undef USE_XIM
 
+/* Define if we have the session management (SM) library.  */
+#undef HAVE_X_SM
+
 /* Define if netdb.h declares h_errno.  */
 #undef HAVE_H_ERRNO
 
Index: src/xsmfns.c
--- src/xsmfns.c.orig   Sun Feb 17 01:58:43 2002
+++ src/xsmfns.c        Tue Feb 26 22:48:49 2002
@@ -0,0 +1,626 @@
+/* Session management module for systems which understand the X Session
+   management protocol.
+   Copyright (C) 2002 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs; see the file COPYING.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+#include <config.h>
+
+#ifdef HAVE_X_SM
+
+#include <X11/SM/SMlib.h>
+#ifdef HAVE_STRING_H
+#include <string.h>
+#else
+#ifdef HAVE_STRINGS_H
+#include <strings.h>
+#endif
+#endif
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "systime.h"
+#include "sysselect.h"
+#include "lisp.h"
+#include "termhooks.h"
+
+#if !defined(S_ISDIR) && defined(S_IFDIR)
+#define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
+#endif
+
+#define PATH_SEP_CHAR   '/'
+#define PATH_SEP_STR    "/"
+
+#ifndef MAXPATHLEN
+#define MAXPATHLEN 1024
+#endif /* not MAXPATHLEN */
+
+
+extern char *getenv ();
+
+
+/* This is the event used when save_session occurs */
+
+static struct input_event emacs_event;
+
+/* The descriptor that we use to check for data from the session manager. */
+
+static int ice_fd = -1;
+
+/* A flag that says if we are in shutdown interactions or not. */
+
+static int doing_interact = False;
+
+/* Initial values of argv.  */
+
+extern char **initial_argv;
+
+/* The session manager object for the session manager connection */
+
+static SmcConn smc_conn;
+
+/* The client session id for this session */
+static char *client_id;
+
+/* The client session id for this session as a lisp object. */
+
+Lisp_Object Vx_session_id;
+
+/* The id we had the previous session.  This is only available if we
+   have been started by the session manager with SMID_OPT. */
+
+Lisp_Object Vx_session_previous_id;
+
+/* The option we tell the session manager to start Emacs with when
+   restarting Emacs.  The client_id is appended. */
+
+#define SMID_OPT "--smid="
+
+
+/* Return non-zero if PATH is an executable file. */
+static int
+executable_file_p (path)
+     char *path;
+{
+  struct stat status;
+
+  return (access (path, X_OK) == 0              /* exists and is executable */
+          && stat (path, &status) == 0          /* get the status */
+          && (S_ISDIR (status.st_mode)) == 0);  /* not a directory */
+}
+
+/* If FILENAME is not an absolute path, make it so by prepending
+   CURRENT_DIRECTORY.  The return value is allocated with malloc and
+   the caller must free it. */
+static char*
+make_absolute_path (filename, current_directory)
+     char *filename;
+     char *current_directory;
+{
+  if (filename[0] == PATH_SEP_CHAR || ! current_directory)
+    return xstrdup (filename);
+  
+  if (strchr (filename, PATH_SEP_CHAR))
+    {
+      char *ret;
+      
+      ret = xmalloc (strlen (filename)+strlen (current_directory)+2);
+      strcpy (ret, current_directory);
+      strcat (ret, PATH_SEP_STR);
+      strcat (ret, filename);
+
+      return ret;
+    }
+
+  return xstrdup (filename);
+}
+
+/* Try to find program by searching path from environment.  If not found,
+   the CURRENT_DIRECTORY concatenated with PROGRAM is returned.
+   The return value is allocated with malloc and the caller must free it. */
+static char*
+path_search (program, current_directory)
+     char *program;
+     char *current_directory;
+{
+  char* bp;
+  char* ep;
+  char *ret;
+  size_t proglen = strlen (program);
+  
+  if (strchr(program, PATH_SEP_CHAR) || ! (bp = getenv ("PATH")))
+      return make_absolute_path (program, current_directory);
+  
+  while (bp)
+    {
+      size_t len;
+      
+      ep = strchr (bp, ':');
+      if (ep == bp || bp[0] == '\0')
+        {
+          /* Empty PATH component, treat as current directory */
+          bp = ".";
+          len = 1;
+        }
+      else if (ep) len = ep-bp;
+      else len = strlen (bp);
+
+      if (proglen+len+1 <= MAXPATHLEN)
+        {
+          char maybe[MAXPATHLEN+1];
+
+          strncpy (maybe, bp, len);
+          maybe[len] = '\0';
+          strcat (maybe, PATH_SEP_STR);
+          strcat (maybe, program);
+          if (executable_file_p (maybe))
+            return make_absolute_path (maybe, current_directory);
+        }
+
+      if (ep) bp = ep+1;
+      else bp = ep;
+    }
+  
+  return make_absolute_path (program, current_directory);
+}
+
+/* Handle any messages from the session manager.  If no connection is
+   open to a session manager, just return 0.
+   Otherwise returns the number of events stored in buffer BUFP,
+   which can hold up to *NUMCHARS characters.  At most one event is
+   stored, an save_session_event. */
+int
+x_session_check_input (bufp, numchars)
+     struct input_event *bufp;
+     int *numchars;
+{
+  SELECT_TYPE read_fds;
+  EMACS_TIME tmout;
+  
+  if (ice_fd == -1) return 0;
+  
+  FD_ZERO (&read_fds);
+  FD_SET (ice_fd, &read_fds);
+      
+  tmout.tv_sec = 0;
+  tmout.tv_usec = 0;
+  
+  /* Reset this so wo can check kind after callbacks have been called by
+     IceProcessMessages.  The smc_interact_CB sets the kind to
+     save_session_event, but we don't know beforehand if that callback
+     will be called. */
+  emacs_event.kind = no_event;
+
+  if (select (ice_fd+1, &read_fds,
+              (SELECT_TYPE *)0, (SELECT_TYPE *)0, &tmout) < 0)
+    {
+      ice_fd = -1;
+      return 0;
+    }
+  
+
+  if (FD_ISSET (ice_fd, &read_fds))
+    IceProcessMessages (SmcGetIceConnection (smc_conn),
+                        (IceReplyWaitInfo *)0, (Bool *)0);
+
+  
+  /* Check if smc_interact_CB was called and we shall generate a
+     save_session event. */
+  if (*numchars > 0 && emacs_event.kind != no_event)
+    {
+      bcopy (&emacs_event, bufp, sizeof (struct input_event));
+      bufp++;
+      (*numchars)--;
+
+      return 1;
+    }
+
+  return 0;
+}
+
+/* Return non-zero if we have a connection to a session manager.*/
+int
+x_session_have_connection ()
+{
+  return ice_fd != -1;
+}
+
+/* This is called when the session manager says it is OK to interact with the
+   user.  Here we set the kind to save_session so an event is generated.
+   Then lisp code can interact with the user. */
+static void
+smc_interact_CB (smcConn, clientData)
+     SmcConn smcConn;
+     SmPointer clientData;
+{
+  doing_interact = True;
+  emacs_event.kind = save_session_event;
+}
+
+/* This is called when the session manager tells us to save ourself.
+   We set the required properties so the session manager can restart us,
+   plus the current working directory property (not mandatory) so we
+   are started in the correct directory.
+
+   If this is a shutdown and we can request to interact with the user,
+   we do so, because we don't know what the lisp code might do. */
+static void
+smc_save_yourself_CB (smcConn,
+                      clientData,
+                      saveType,
+                      shutdown,
+                      interactStyle,
+                      fast)
+     SmcConn smcConn;
+     SmPointer clientData;
+     int saveType;
+     Bool shutdown;
+     int interactStyle;
+     Bool fast;
+{
+#define NR_PROPS 5
+  
+  SmProp *props[NR_PROPS];
+  SmProp prop_ptr[NR_PROPS];
+  
+  SmPropValue values[20];
+  int val_idx = 0;
+  int props_idx = 0;
+  int has_cwd;
+  
+  char cwd[MAXPATHLEN+1];
+  char user_id[16];
+
+  char *program;
+  char *smid_opt;
+
+#ifdef HAVE_GETCWD
+  has_cwd = getcwd (cwd, MAXPATHLEN+1) != 0;
+#else
+  has_cwd = getwd (cwd) != 0;
+#endif
+  
+  if (has_cwd)
+    program = path_search (initial_argv[0], cwd);
+  else
+    program = path_search (initial_argv[0], 0);
+  
+  /* How to start a new instance of Emacs */
+  props[props_idx] = &prop_ptr[props_idx];
+  props[props_idx]->name = SmCloneCommand;
+  props[props_idx]->type = SmLISTofARRAY8;
+  props[props_idx]->num_vals = 1;
+  props[props_idx]->vals = &values[val_idx++];
+  props[props_idx]->vals[0].length = strlen (program);
+  props[props_idx]->vals[0].value = program;
+  ++props_idx;
+
+  /* The name of the program */
+  props[props_idx] = &prop_ptr[props_idx];
+  props[props_idx]->name = SmProgram;
+  props[props_idx]->type = SmARRAY8;
+  props[props_idx]->num_vals = 1;
+  props[props_idx]->vals = &values[val_idx++];
+  props[props_idx]->vals[0].length = strlen (initial_argv[0]);
+  props[props_idx]->vals[0].value = initial_argv[0];
+  ++props_idx;
+  
+  /* How to restart Emacs (i.e.: /path/to/emacs --smid=xxxx). */
+  props[props_idx] = &prop_ptr[props_idx];
+  props[props_idx]->name = SmRestartCommand;
+  props[props_idx]->type = SmLISTofARRAY8;
+  props[props_idx]->num_vals = 2; /* 2 values: /path/to/emacs, --smid=xxx */
+  props[props_idx]->vals = &values[val_idx];
+  props[props_idx]->vals[0].length = strlen (program);
+  props[props_idx]->vals[0].value = program;
+
+  smid_opt = xmalloc (strlen (SMID_OPT) + strlen (client_id) + 1);
+  strcpy(smid_opt, SMID_OPT);
+  strcat(smid_opt, client_id);
+  
+  props[props_idx]->vals[1].length = strlen (smid_opt);
+  props[props_idx]->vals[1].value = smid_opt;
+  val_idx += 2;
+  ++props_idx;
+
+  /* User id */
+  sprintf(user_id, "%d", getpid());
+  props[props_idx] = &prop_ptr[props_idx];
+  props[props_idx]->name = SmUserID;
+  props[props_idx]->type = SmARRAY8;
+  props[props_idx]->num_vals = 1;
+  props[props_idx]->vals = &values[val_idx++];
+  props[props_idx]->vals[0].length = strlen (user_id);
+  props[props_idx]->vals[0].value = user_id;
+  ++props_idx;
+
+  /* The current directory property, not mandatory */
+  if (has_cwd)
+    {
+      props[props_idx] = &prop_ptr[props_idx];
+      props[props_idx]->name = SmCurrentDirectory;
+      props[props_idx]->type = SmARRAY8;
+      props[props_idx]->num_vals = 1;
+      props[props_idx]->vals = &values[val_idx++];
+      props[props_idx]->vals[0].length = strlen (cwd);
+      props[props_idx]->vals[0].value = cwd;
+      ++props_idx;
+    }
+  
+  
+  SmcSetProperties (smcConn, props_idx, props);
+
+  xfree (program);
+  xfree (smid_opt);
+
+  /* See if we maybe shall interact with the user. */
+  if (interactStyle != SmInteractStyleAny
+      || ! shutdown
+      || saveType == SmSaveLocal
+      || ! SmcInteractRequest(smcConn, SmDialogNormal, smc_interact_CB, 0))
+    {
+      /* No interaction, we are done saving ourself. */
+      SmcSaveYourselfDone (smcConn, True);
+    }
+}
+
+/* According to the SM specification, this shall close the connection */
+static void
+smc_die_CB (smcConn, clientData)
+     SmcConn smcConn;
+     SmPointer clientData;
+{
+  SmcCloseConnection (smcConn, 0, 0);
+  ice_fd = -1;
+}
+
+/* We don't use the next two but they are mandatory, leave them empty.
+   According to the SM specification, we should not interact with the
+   user between smc_save_yourself_CB is called and until smc_save_complete_CB
+   is called.  It seems like a lot of job to implement this and it doesn't
+   even seem necessary. */
+static void
+smc_save_complete_CB (smcConn, clientData)
+     SmcConn smcConn;
+     SmPointer clientData;
+{
+  /* Empty */
+}
+
+static void
+smc_shutdown_cancelled_CB (smcConn, clientData)
+     SmcConn smcConn;
+     SmPointer clientData;
+{
+  /* Empty */
+}
+
+/* Error handlers for SM and ICE.  We don't wan't to exit Emacs just
+   because there is some error in the session management. */
+static void
+smc_error_handler (smcConn,
+                   swap,
+                   offendingMinorOpcode,
+                   offendingSequence,
+                   errorClass,
+                   severity,
+                   values)
+     SmcConn smcConn;
+     Bool swap;
+     int offendingMinorOpcode;
+     unsigned long offendingSequence;
+     int errorClass;
+     int severity;
+     SmPointer values;
+{
+  /* Empty */
+}
+
+static void
+ice_error_handler (iceConn,
+                   swap,
+                   offendingMinorOpcode,
+                   offendingSequence,
+                   errorClass,
+                   severity,
+                   values)
+     IceConn iceConn;
+     Bool swap;
+     int offendingMinorOpcode;
+     unsigned long offendingSequence;
+     int errorClass;
+     int severity;
+     IcePointer values;
+{
+  /* Empty */
+}
+
+
+static void
+ice_io_error_handler (iceConn)
+     IceConn iceConn;
+{
+  /* Connection probably gone. */
+  ice_fd = -1;
+}
+
+/* This is called when the ICE connection is created or closed.  The SM library
+   uses ICE as it transport protocol. */
+static void
+ice_conn_watch_CB (iceConn, clientData, opening, watchData)
+     IceConn iceConn;
+     IcePointer clientData;
+     Bool opening;
+     IcePointer *watchData;
+{
+  if (! opening)
+    {
+      ice_fd = -1;
+      return;
+    }
+  
+  ice_fd = IceConnectionNumber (iceConn);
+#ifndef F_SETOWN_BUG
+#ifdef F_SETOWN
+#ifdef F_SETOWN_SOCK_NEG
+  /* stdin is a socket here */
+  fcntl (ice_fd, F_SETOWN, -getpid ());
+#else /* ! defined (F_SETOWN_SOCK_NEG) */
+  fcntl (ice_fd, F_SETOWN, getpid ());
+#endif /* ! defined (F_SETOWN_SOCK_NEG) */
+#endif /* ! defined (F_SETOWN) */
+#endif /* F_SETOWN_BUG */
+
+#ifdef SIGIO
+  if (interrupt_input)
+    init_sigio (ice_fd);
+#endif /* ! defined (SIGIO) */
+}
+
+/* Try to open a connection to the session manager. */
+void
+x_session_initialize ()
+{
+#define SM_ERRORSTRING_LEN 512
+  char errorstring[SM_ERRORSTRING_LEN];
+  char* previous_id = NULL;
+  SmcCallbacks callbacks;
+  
+  /* Check if we where started by the session manager.  If so, we will
+     have a previous id. */
+  if (! EQ (Vx_session_previous_id, Qnil) && STRINGP (Vx_session_previous_id))
+    previous_id = XSTRING (Vx_session_previous_id)->data;
+
+  /* The SM protocol says all callbacks are mandatory, so set up all
+     here and in the mask passed to SmcOpenConnection */
+  callbacks.save_yourself.callback = smc_save_yourself_CB;
+  callbacks.save_yourself.client_data = 0;
+  callbacks.die.callback = smc_die_CB;
+  callbacks.die.client_data = 0;
+  callbacks.save_complete.callback = smc_save_complete_CB;
+  callbacks.save_complete.client_data = 0;
+  callbacks.shutdown_cancelled.callback = smc_shutdown_cancelled_CB;
+  callbacks.shutdown_cancelled.client_data = 0;
+
+  /* Set error handlers. */
+  SmcSetErrorHandler (smc_error_handler);
+  IceSetErrorHandler (ice_error_handler);
+  IceSetIOErrorHandler (ice_io_error_handler);
+
+  /* Install callback for when connection status changes. */
+  IceAddConnectionWatch (ice_conn_watch_CB, 0);
+
+  /* Open the connection to the session manager.  A failure is not
+     critical, it usualy means that no session manager is running.
+     The errorstring is here for debugging. */
+  smc_conn = SmcOpenConnection (NULL, NULL, 1, 0,
+                                (SmcSaveYourselfProcMask|
+                                 SmcDieProcMask|
+                                 SmcSaveCompleteProcMask|
+                                 SmcShutdownCancelledProcMask),
+                                &callbacks,
+                                previous_id,
+                                &client_id,
+                                SM_ERRORSTRING_LEN,
+                                errorstring);
+
+  if (smc_conn != 0)
+    Vx_session_id = make_string (client_id, strlen (client_id));
+}
+
+
+DEFUN ("handle-save-session", Fhandle_save_session,
+       Shandle_save_session, 1, 1, "e",
+       doc: /* Handle the save_yourself event from a session manager.
+A session manager can tell Emacs that the window system is shutting down 
+by sending Emacs a save_yourself message.  Emacs executes this function when
+such an event occurs.  This function then executes `emacs-session-save'.
+After that, this function informs the session manager that it can continue
+or abort shutting down the window system depending on the return value
+from `emacs-session-save'  If the return value is non-nil the session manager
+is told to abort the window system shutdown.
+
+Do not call this function yourself. */)
+     (event)
+     Lisp_Object event;
+{
+  /* Check doing_interact so that we don't do anything if someone called
+     this at the wrong time. */
+  if (doing_interact)
+    {
+      Bool cancel_shutdown = False;
+
+      cancel_shutdown = ! EQ (call0 (intern ("emacs-session-save")), Qnil);
+
+      SmcInteractDone (smc_conn, cancel_shutdown);
+      SmcSaveYourselfDone (smc_conn, True);
+
+      doing_interact = False;
+    }
+}
+
+
+/***********************************************************************
+                           Initialization
+ ***********************************************************************/
+void
+syms_of_xsmfns ()
+{
+  DEFVAR_LISP ("x-session-id", &Vx_session_id,
+    doc: /* The session id Emacs got from the session manager for this session.
+Changing the value does not change the session id used by Emacs.
+The value is nil if no session manager is running.
+See also `x-session-previous-id', `emacs-save-session-functions',
+`emacs-session-save' and `emacs-session-restore'." */);
+  Vx_session_id = Qnil;
+
+  DEFVAR_LISP ("x-session-previous-id", &Vx_session_previous_id,
+    doc: /* The previous session id Emacs got from session manager.
+If Emacs is running on a window system that has a session manager, the 
+session manager gives Emacs a session id.  It is feasible for Emacs lisp 
+code to use the session id to save configuration in, for example, a file 
+with a file name based on the session id.  If Emacs is running when the 
+window system is shut down, the session manager remembers that Emacs was 
+running and saves the session id Emacs had.
+
+When the window system is started again, the session manager restarts 
+Emacs and hands Emacs the session id it had the last time it was 
+running.  This is now the previous session id and the value of this 
+variable.  If configuration was saved in a file as stated above, the 
+previous session id shall be used to reconstruct the file name.
+
+The session id Emacs has while it is running is in the variable 
+`x-session-id'.  The value of this variable and `x-session-id' may be the
+same, depending on how the session manager works.
+
+See also `emacs-save-session-functions', `emacs-session-save' and
+`emacs-session-restore'." */);
+  Vx_session_previous_id = Qnil;
+  
+  defsubr (&Shandle_save_session);
+}
+
+#endif /* HAVE_X_SM */
Index: configure.in
--- configure.in.orig   Sun Jan 27 11:03:14 2002
+++ configure.in        Tue Feb 26 22:48:49 2002
@@ -1915,6 +1915,21 @@
   fi
 fi
 
+### Use session management (-lSM -lICE) if available
+HAVE_X_SM=no
+if test "${HAVE_X11}" = "yes"; then
+  AC_CHECK_HEADER(X11/SM/SMlib.h,
+    AC_CHECK_LIB(SM, SmcOpenConnection, HAVE_X_SM=yes, -lICE))
+
+  if test "${HAVE_X_SM}" = "yes"; then
+    AC_DEFINE(HAVE_X_SM)
+    case "$LIBS" in
+      *-lSM*) ;;
+      *)      LIBS="-lSM -lICE $LIBS" ;;
+    esac
+  fi
+fi
+  
 # If netdb.h doesn't declare h_errno, we must declare it by hand.
 AC_CACHE_CHECK(whether netdb declares h_errno,
               emacs_cv_netdb_declares_h_errno,