| 1 | /* Session management module for systems which understand the X Session |
| 2 | management protocol. |
| 3 | Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 |
| 4 | Free Software Foundation, Inc. |
| 5 | |
| 6 | This file is part of GNU Emacs. |
| 7 | |
| 8 | GNU Emacs is free software: you can redistribute it and/or modify |
| 9 | it under the terms of the GNU General Public License as published by |
| 10 | the Free Software Foundation, either version 3 of the License, or |
| 11 | (at your option) any later version. |
| 12 | |
| 13 | GNU Emacs is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
| 18 | You should have received a copy of the GNU General Public License |
| 19 | along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */ |
| 20 | |
| 21 | #include <config.h> |
| 22 | |
| 23 | #ifdef HAVE_X_SM |
| 24 | |
| 25 | #include <X11/SM/SMlib.h> |
| 26 | #include <X11/Xlib.h> |
| 27 | #include <X11/Xutil.h> |
| 28 | |
| 29 | #include <unistd.h> |
| 30 | #include <sys/param.h> |
| 31 | #include <stdio.h> |
| 32 | #include <setjmp.h> |
| 33 | |
| 34 | #include "lisp.h" |
| 35 | #include "systime.h" |
| 36 | #include "sysselect.h" |
| 37 | #include "frame.h" |
| 38 | #include "termhooks.h" |
| 39 | #include "termopts.h" |
| 40 | #include "xterm.h" |
| 41 | |
| 42 | /* This is the event used when SAVE_SESSION_EVENT occurs. */ |
| 43 | |
| 44 | static struct input_event emacs_event; |
| 45 | |
| 46 | /* The descriptor that we use to check for data from the session manager. */ |
| 47 | |
| 48 | static int ice_fd; |
| 49 | |
| 50 | /* A flag that says if we are in shutdown interactions or not. */ |
| 51 | |
| 52 | static int doing_interact; |
| 53 | |
| 54 | /* The session manager object for the session manager connection. */ |
| 55 | |
| 56 | static SmcConn smc_conn; |
| 57 | |
| 58 | /* The client session id for this session. */ |
| 59 | |
| 60 | static char *client_id; |
| 61 | |
| 62 | /* The full path name to the Emacs program. */ |
| 63 | |
| 64 | static char *emacs_program; |
| 65 | |
| 66 | /* The option we tell the session manager to start Emacs with when |
| 67 | restarting Emacs. The client_id is appended. */ |
| 68 | |
| 69 | #define SMID_OPT "--smid=" |
| 70 | |
| 71 | |
| 72 | /* The option to start Emacs without the splash screen when |
| 73 | restarting Emacs. */ |
| 74 | |
| 75 | static char NOSPLASH_OPT[] = "--no-splash"; |
| 76 | |
| 77 | /* The option to make Emacs start in the given directory. */ |
| 78 | |
| 79 | #define CHDIR_OPT "--chdir=" |
| 80 | |
| 81 | static void |
| 82 | ice_connection_closed (void) |
| 83 | { |
| 84 | if (ice_fd >= 0) |
| 85 | delete_keyboard_wait_descriptor (ice_fd); |
| 86 | ice_fd = -1; |
| 87 | } |
| 88 | |
| 89 | |
| 90 | /* Handle any messages from the session manager. If no connection is |
| 91 | open to a session manager, just return 0. |
| 92 | Otherwise returns 1 if SAVE_SESSION_EVENT is stored in buffer BUFP. */ |
| 93 | |
| 94 | int |
| 95 | x_session_check_input (struct input_event *bufp) |
| 96 | { |
| 97 | SELECT_TYPE read_fds; |
| 98 | EMACS_TIME tmout; |
| 99 | int ret; |
| 100 | |
| 101 | if (ice_fd == -1) return 0; |
| 102 | FD_ZERO (&read_fds); |
| 103 | FD_SET (ice_fd, &read_fds); |
| 104 | |
| 105 | tmout.tv_sec = 0; |
| 106 | tmout.tv_usec = 0; |
| 107 | |
| 108 | /* Reset this so wo can check kind after callbacks have been called by |
| 109 | IceProcessMessages. The smc_interact_CB sets the kind to |
| 110 | SAVE_SESSION_EVENT, but we don't know beforehand if that callback |
| 111 | will be called. */ |
| 112 | emacs_event.kind = NO_EVENT; |
| 113 | |
| 114 | ret = select (ice_fd+1, &read_fds, |
| 115 | (SELECT_TYPE *)0, (SELECT_TYPE *)0, &tmout); |
| 116 | |
| 117 | if (ret < 0) |
| 118 | { |
| 119 | ice_connection_closed (); |
| 120 | } |
| 121 | else if (ret > 0 && FD_ISSET (ice_fd, &read_fds)) |
| 122 | { |
| 123 | ret = IceProcessMessages (SmcGetIceConnection (smc_conn), |
| 124 | (IceReplyWaitInfo *)0, (Bool *)0); |
| 125 | if (ret != IceProcessMessagesSuccess) |
| 126 | { |
| 127 | /* Either IO error or Connection closed. */ |
| 128 | if (ret == IceProcessMessagesIOError) |
| 129 | IceCloseConnection (SmcGetIceConnection (smc_conn)); |
| 130 | |
| 131 | ice_connection_closed (); |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | /* Check if smc_interact_CB was called and we shall generate a |
| 136 | SAVE_SESSION_EVENT. */ |
| 137 | if (emacs_event.kind != NO_EVENT) |
| 138 | memcpy (bufp, &emacs_event, sizeof (struct input_event)); |
| 139 | |
| 140 | return emacs_event.kind != NO_EVENT ? 1 : 0; |
| 141 | } |
| 142 | |
| 143 | /* Return non-zero if we have a connection to a session manager. */ |
| 144 | |
| 145 | int |
| 146 | x_session_have_connection (void) |
| 147 | { |
| 148 | return ice_fd != -1; |
| 149 | } |
| 150 | |
| 151 | /* This is called when the session manager says it is OK to interact with the |
| 152 | user. Here we set the kind to SAVE_SESSION_EVENT so an event is generated. |
| 153 | Then lisp code can interact with the user. */ |
| 154 | |
| 155 | static void |
| 156 | smc_interact_CB (SmcConn smcConn, SmPointer clientData) |
| 157 | { |
| 158 | doing_interact = True; |
| 159 | emacs_event.kind = SAVE_SESSION_EVENT; |
| 160 | emacs_event.arg = Qnil; |
| 161 | } |
| 162 | |
| 163 | /* This is called when the session manager tells us to save ourselves. |
| 164 | We set the required properties so the session manager can restart us, |
| 165 | plus the current working directory property (not mandatory) so we |
| 166 | are started in the correct directory. |
| 167 | |
| 168 | If this is a shutdown and we can request to interact with the user, |
| 169 | we do so, because we don't know what the lisp code might do. */ |
| 170 | |
| 171 | static void |
| 172 | smc_save_yourself_CB (SmcConn smcConn, |
| 173 | SmPointer clientData, |
| 174 | int saveType, |
| 175 | Bool shutdown, |
| 176 | int interactStyle, |
| 177 | Bool fast) |
| 178 | { |
| 179 | #define NR_PROPS 5 |
| 180 | |
| 181 | SmProp *props[NR_PROPS]; |
| 182 | SmProp prop_ptr[NR_PROPS]; |
| 183 | |
| 184 | SmPropValue values[20]; |
| 185 | int val_idx = 0; |
| 186 | int props_idx = 0; |
| 187 | int i; |
| 188 | char *cwd = NULL; |
| 189 | char *smid_opt, *chdir_opt = NULL; |
| 190 | |
| 191 | /* How to start a new instance of Emacs. */ |
| 192 | props[props_idx] = &prop_ptr[props_idx]; |
| 193 | props[props_idx]->name = xstrdup (SmCloneCommand); |
| 194 | props[props_idx]->type = xstrdup (SmLISTofARRAY8); |
| 195 | props[props_idx]->num_vals = 1; |
| 196 | props[props_idx]->vals = &values[val_idx++]; |
| 197 | props[props_idx]->vals[0].length = strlen (emacs_program); |
| 198 | props[props_idx]->vals[0].value = emacs_program; |
| 199 | ++props_idx; |
| 200 | |
| 201 | /* The name of the program. */ |
| 202 | props[props_idx] = &prop_ptr[props_idx]; |
| 203 | props[props_idx]->name = xstrdup (SmProgram); |
| 204 | props[props_idx]->type = xstrdup (SmARRAY8); |
| 205 | props[props_idx]->num_vals = 1; |
| 206 | props[props_idx]->vals = &values[val_idx++]; |
| 207 | props[props_idx]->vals[0].length = strlen (SSDATA (Vinvocation_name)); |
| 208 | props[props_idx]->vals[0].value = SDATA (Vinvocation_name); |
| 209 | ++props_idx; |
| 210 | |
| 211 | /* How to restart Emacs. */ |
| 212 | props[props_idx] = &prop_ptr[props_idx]; |
| 213 | props[props_idx]->name = xstrdup (SmRestartCommand); |
| 214 | props[props_idx]->type = xstrdup (SmLISTofARRAY8); |
| 215 | /* /path/to/emacs, --smid=xxx --no-splash --chdir=dir */ |
| 216 | props[props_idx]->num_vals = 4; |
| 217 | props[props_idx]->vals = &values[val_idx]; |
| 218 | props[props_idx]->vals[0].length = strlen (emacs_program); |
| 219 | props[props_idx]->vals[0].value = emacs_program; |
| 220 | |
| 221 | smid_opt = xmalloc (strlen (SMID_OPT) + strlen (client_id) + 1); |
| 222 | strcpy (smid_opt, SMID_OPT); |
| 223 | strcat (smid_opt, client_id); |
| 224 | |
| 225 | props[props_idx]->vals[1].length = strlen (smid_opt); |
| 226 | props[props_idx]->vals[1].value = smid_opt; |
| 227 | |
| 228 | props[props_idx]->vals[2].length = strlen (NOSPLASH_OPT); |
| 229 | props[props_idx]->vals[2].value = NOSPLASH_OPT; |
| 230 | |
| 231 | cwd = get_current_dir_name (); |
| 232 | if (cwd) |
| 233 | { |
| 234 | chdir_opt = xmalloc (strlen (CHDIR_OPT) + strlen (cwd) + 1); |
| 235 | strcpy (chdir_opt, CHDIR_OPT); |
| 236 | strcat (chdir_opt, cwd); |
| 237 | |
| 238 | props[props_idx]->vals[3].length = strlen (chdir_opt); |
| 239 | props[props_idx]->vals[3].value = chdir_opt; |
| 240 | } |
| 241 | |
| 242 | val_idx += cwd ? 4 : 3; |
| 243 | ++props_idx; |
| 244 | |
| 245 | /* User id. */ |
| 246 | props[props_idx] = &prop_ptr[props_idx]; |
| 247 | props[props_idx]->name = xstrdup (SmUserID); |
| 248 | props[props_idx]->type = xstrdup (SmARRAY8); |
| 249 | props[props_idx]->num_vals = 1; |
| 250 | props[props_idx]->vals = &values[val_idx++]; |
| 251 | props[props_idx]->vals[0].length = strlen (SSDATA (Vuser_login_name)); |
| 252 | props[props_idx]->vals[0].value = SDATA (Vuser_login_name); |
| 253 | ++props_idx; |
| 254 | |
| 255 | |
| 256 | if (cwd) |
| 257 | { |
| 258 | props[props_idx] = &prop_ptr[props_idx]; |
| 259 | props[props_idx]->name = xstrdup (SmCurrentDirectory); |
| 260 | props[props_idx]->type = xstrdup (SmARRAY8); |
| 261 | props[props_idx]->num_vals = 1; |
| 262 | props[props_idx]->vals = &values[val_idx++]; |
| 263 | props[props_idx]->vals[0].length = strlen (cwd); |
| 264 | props[props_idx]->vals[0].value = cwd; |
| 265 | ++props_idx; |
| 266 | } |
| 267 | |
| 268 | |
| 269 | SmcSetProperties (smcConn, props_idx, props); |
| 270 | |
| 271 | xfree (smid_opt); |
| 272 | xfree (chdir_opt); |
| 273 | |
| 274 | free (cwd); |
| 275 | for (i = 0; i < props_idx; ++i) |
| 276 | { |
| 277 | xfree (props[i]->type); |
| 278 | xfree (props[i]->name); |
| 279 | } |
| 280 | |
| 281 | /* See if we maybe shall interact with the user. */ |
| 282 | if (interactStyle != SmInteractStyleAny |
| 283 | || ! shutdown |
| 284 | || saveType == SmSaveLocal |
| 285 | || ! SmcInteractRequest (smcConn, SmDialogNormal, smc_interact_CB, 0)) |
| 286 | { |
| 287 | /* No interaction, we are done saving ourself. */ |
| 288 | SmcSaveYourselfDone (smcConn, True); |
| 289 | } |
| 290 | } |
| 291 | |
| 292 | /* According to the SM specification, this shall close the connection. */ |
| 293 | |
| 294 | static void |
| 295 | smc_die_CB (SmcConn smcConn, SmPointer clientData) |
| 296 | { |
| 297 | emacs_event.kind = SAVE_SESSION_EVENT; |
| 298 | emacs_event.arg = Qt; |
| 299 | } |
| 300 | |
| 301 | /* We don't use the next two but they are mandatory, leave them empty. |
| 302 | According to the SM specification, we should not interact with the |
| 303 | user between smc_save_yourself_CB is called and until smc_save_complete_CB |
| 304 | is called. It seems like a lot of job to implement this and it doesn't |
| 305 | even seem necessary. */ |
| 306 | |
| 307 | static void |
| 308 | smc_save_complete_CB (SmcConn smcConn, SmPointer clientData) |
| 309 | { |
| 310 | /* Empty */ |
| 311 | } |
| 312 | |
| 313 | static void |
| 314 | smc_shutdown_cancelled_CB (SmcConn smcConn, SmPointer clientData) |
| 315 | { |
| 316 | /* Empty */ |
| 317 | } |
| 318 | |
| 319 | /* Error handlers for SM and ICE. We don't want to exit Emacs just |
| 320 | because there is some error in the session management. */ |
| 321 | |
| 322 | static void |
| 323 | smc_error_handler (SmcConn smcConn, |
| 324 | Bool swap, |
| 325 | int offendingMinorOpcode, |
| 326 | unsigned long offendingSequence, |
| 327 | int errorClass, |
| 328 | int severity, |
| 329 | SmPointer values) |
| 330 | { |
| 331 | /* Empty */ |
| 332 | } |
| 333 | |
| 334 | static void |
| 335 | ice_error_handler (IceConn iceConn, |
| 336 | Bool swap, |
| 337 | int offendingMinorOpcode, |
| 338 | unsigned long offendingSequence, |
| 339 | int errorClass, |
| 340 | int severity, |
| 341 | IcePointer values) |
| 342 | { |
| 343 | /* Empty */ |
| 344 | } |
| 345 | |
| 346 | |
| 347 | static void |
| 348 | ice_io_error_handler (IceConn iceConn) |
| 349 | { |
| 350 | /* Connection probably gone. */ |
| 351 | ice_connection_closed (); |
| 352 | } |
| 353 | |
| 354 | /* This is called when the ICE connection is created or closed. The SM library |
| 355 | uses ICE as it transport protocol. */ |
| 356 | |
| 357 | static void |
| 358 | ice_conn_watch_CB (IceConn iceConn, IcePointer clientData, int opening, IcePointer *watchData) |
| 359 | { |
| 360 | if (! opening) |
| 361 | { |
| 362 | ice_connection_closed (); |
| 363 | return; |
| 364 | } |
| 365 | |
| 366 | ice_fd = IceConnectionNumber (iceConn); |
| 367 | #ifdef F_SETOWN |
| 368 | fcntl (ice_fd, F_SETOWN, getpid ()); |
| 369 | #endif /* ! defined (F_SETOWN) */ |
| 370 | |
| 371 | #ifdef SIGIO |
| 372 | if (interrupt_input) |
| 373 | init_sigio (ice_fd); |
| 374 | #endif /* ! defined (SIGIO) */ |
| 375 | |
| 376 | add_keyboard_wait_descriptor (ice_fd); |
| 377 | } |
| 378 | |
| 379 | /* Create the client leader window. */ |
| 380 | |
| 381 | #ifndef USE_GTK |
| 382 | static void |
| 383 | create_client_leader_window (struct x_display_info *dpyinfo, char *client_id) |
| 384 | { |
| 385 | Window w; |
| 386 | XClassHint class_hints; |
| 387 | Atom sm_id; |
| 388 | |
| 389 | w = XCreateSimpleWindow (dpyinfo->display, |
| 390 | dpyinfo->root_window, |
| 391 | -1, -1, 1, 1, |
| 392 | CopyFromParent, CopyFromParent, CopyFromParent); |
| 393 | |
| 394 | class_hints.res_name = SSDATA (Vx_resource_name); |
| 395 | class_hints.res_class = SSDATA (Vx_resource_class); |
| 396 | XSetClassHint (dpyinfo->display, w, &class_hints); |
| 397 | XStoreName (dpyinfo->display, w, class_hints.res_name); |
| 398 | |
| 399 | XChangeProperty (dpyinfo->display, w, dpyinfo->Xatom_SM_CLIENT_ID, |
| 400 | XA_STRING, 8, PropModeReplace, |
| 401 | (unsigned char *)client_id, strlen (client_id)); |
| 402 | |
| 403 | dpyinfo->client_leader_window = w; |
| 404 | } |
| 405 | #endif /* ! USE_GTK */ |
| 406 | |
| 407 | |
| 408 | /* Try to open a connection to the session manager. */ |
| 409 | |
| 410 | void |
| 411 | x_session_initialize (struct x_display_info *dpyinfo) |
| 412 | { |
| 413 | #define SM_ERRORSTRING_LEN 512 |
| 414 | char errorstring[SM_ERRORSTRING_LEN]; |
| 415 | char* previous_id = NULL; |
| 416 | SmcCallbacks callbacks; |
| 417 | int name_len = 0; |
| 418 | |
| 419 | ice_fd = -1; |
| 420 | doing_interact = False; |
| 421 | |
| 422 | /* Check if we where started by the session manager. If so, we will |
| 423 | have a previous id. */ |
| 424 | if (! EQ (Vx_session_previous_id, Qnil) && STRINGP (Vx_session_previous_id)) |
| 425 | previous_id = SSDATA (Vx_session_previous_id); |
| 426 | |
| 427 | /* Construct the path to the Emacs program. */ |
| 428 | if (! EQ (Vinvocation_directory, Qnil)) |
| 429 | name_len += strlen (SSDATA (Vinvocation_directory)); |
| 430 | name_len += strlen (SSDATA (Vinvocation_name)); |
| 431 | |
| 432 | /* This malloc will not be freed, but it is only done once, and hopefully |
| 433 | not very large */ |
| 434 | emacs_program = xmalloc (name_len + 1); |
| 435 | emacs_program[0] = '\0'; |
| 436 | |
| 437 | if (! EQ (Vinvocation_directory, Qnil)) |
| 438 | strcpy (emacs_program, SSDATA (Vinvocation_directory)); |
| 439 | strcat (emacs_program, SSDATA (Vinvocation_name)); |
| 440 | |
| 441 | /* The SM protocol says all callbacks are mandatory, so set up all |
| 442 | here and in the mask passed to SmcOpenConnection. */ |
| 443 | callbacks.save_yourself.callback = smc_save_yourself_CB; |
| 444 | callbacks.save_yourself.client_data = 0; |
| 445 | callbacks.die.callback = smc_die_CB; |
| 446 | callbacks.die.client_data = 0; |
| 447 | callbacks.save_complete.callback = smc_save_complete_CB; |
| 448 | callbacks.save_complete.client_data = 0; |
| 449 | callbacks.shutdown_cancelled.callback = smc_shutdown_cancelled_CB; |
| 450 | callbacks.shutdown_cancelled.client_data = 0; |
| 451 | |
| 452 | /* Set error handlers. */ |
| 453 | SmcSetErrorHandler (smc_error_handler); |
| 454 | IceSetErrorHandler (ice_error_handler); |
| 455 | IceSetIOErrorHandler (ice_io_error_handler); |
| 456 | |
| 457 | /* Install callback for when connection status changes. */ |
| 458 | IceAddConnectionWatch (ice_conn_watch_CB, 0); |
| 459 | |
| 460 | /* Open the connection to the session manager. A failure is not |
| 461 | critical, it usually means that no session manager is running. |
| 462 | The errorstring is here for debugging. */ |
| 463 | smc_conn = SmcOpenConnection (NULL, NULL, 1, 0, |
| 464 | (SmcSaveYourselfProcMask| |
| 465 | SmcDieProcMask| |
| 466 | SmcSaveCompleteProcMask| |
| 467 | SmcShutdownCancelledProcMask), |
| 468 | &callbacks, |
| 469 | previous_id, |
| 470 | &client_id, |
| 471 | SM_ERRORSTRING_LEN, |
| 472 | errorstring); |
| 473 | |
| 474 | if (smc_conn != 0) |
| 475 | { |
| 476 | Vx_session_id = make_string (client_id, strlen (client_id)); |
| 477 | |
| 478 | #ifdef USE_GTK |
| 479 | /* GTK creats a leader window by itself, but we need to tell |
| 480 | it about our client_id. */ |
| 481 | gdk_set_sm_client_id (client_id); |
| 482 | #else |
| 483 | create_client_leader_window (dpyinfo, client_id); |
| 484 | #endif |
| 485 | } |
| 486 | } |
| 487 | |
| 488 | /* Ensure that the session manager is not contacted again. */ |
| 489 | |
| 490 | void |
| 491 | x_session_close (void) |
| 492 | { |
| 493 | ice_connection_closed (); |
| 494 | } |
| 495 | |
| 496 | |
| 497 | DEFUN ("handle-save-session", Fhandle_save_session, |
| 498 | Shandle_save_session, 1, 1, "e", |
| 499 | doc: /* Handle the save_yourself event from a session manager. |
| 500 | A session manager can tell Emacs that the window system is shutting down |
| 501 | by sending Emacs a save_yourself message. Emacs executes this function when |
| 502 | such an event occurs. This function then executes `emacs-session-save'. |
| 503 | After that, this function informs the session manager that it can continue |
| 504 | or abort shutting down the window system depending on the return value |
| 505 | from `emacs-session-save' If the return value is non-nil the session manager |
| 506 | is told to abort the window system shutdown. |
| 507 | |
| 508 | Do not call this function yourself. */) |
| 509 | (Lisp_Object event) |
| 510 | { |
| 511 | int kill_emacs = CONSP (event) && CONSP (XCDR (event)) |
| 512 | && EQ (Qt, XCAR (XCDR (event))); |
| 513 | |
| 514 | /* Check doing_interact so that we don't do anything if someone called |
| 515 | this at the wrong time. */ |
| 516 | if (doing_interact && ! kill_emacs) |
| 517 | { |
| 518 | Bool cancel_shutdown = False; |
| 519 | |
| 520 | cancel_shutdown = ! EQ (call0 (intern ("emacs-session-save")), Qnil); |
| 521 | |
| 522 | SmcInteractDone (smc_conn, cancel_shutdown); |
| 523 | SmcSaveYourselfDone (smc_conn, True); |
| 524 | |
| 525 | doing_interact = False; |
| 526 | } |
| 527 | else if (kill_emacs) |
| 528 | { |
| 529 | /* We should not do user interaction here, but it is not easy to |
| 530 | prevent. Fix this in next version. */ |
| 531 | Fkill_emacs (Qnil); |
| 532 | |
| 533 | /* This will not be reached, but we want kill-emacs-hook to be run. */ |
| 534 | SmcCloseConnection (smc_conn, 0, 0); |
| 535 | ice_connection_closed (); |
| 536 | } |
| 537 | |
| 538 | return Qnil; |
| 539 | } |
| 540 | |
| 541 | |
| 542 | \f |
| 543 | /*********************************************************************** |
| 544 | Initialization |
| 545 | ***********************************************************************/ |
| 546 | void |
| 547 | syms_of_xsmfns (void) |
| 548 | { |
| 549 | DEFVAR_LISP ("x-session-id", Vx_session_id, |
| 550 | doc: /* The session id Emacs got from the session manager for this session. |
| 551 | Changing the value does not change the session id used by Emacs. |
| 552 | The value is nil if no session manager is running. |
| 553 | See also `x-session-previous-id', `emacs-save-session-functions', |
| 554 | `emacs-session-save' and `emacs-session-restore'." */); |
| 555 | Vx_session_id = Qnil; |
| 556 | |
| 557 | DEFVAR_LISP ("x-session-previous-id", Vx_session_previous_id, |
| 558 | doc: /* The previous session id Emacs got from session manager. |
| 559 | If Emacs is running on a window system that has a session manager, the |
| 560 | session manager gives Emacs a session id. It is feasible for Emacs Lisp |
| 561 | code to use the session id to save configuration in, for example, a file |
| 562 | with a file name based on the session id. If Emacs is running when the |
| 563 | window system is shut down, the session manager remembers that Emacs was |
| 564 | running and saves the session id Emacs had. |
| 565 | |
| 566 | When the window system is started again, the session manager restarts |
| 567 | Emacs and hands Emacs the session id it had the last time it was |
| 568 | running. This is now the previous session id and the value of this |
| 569 | variable. If configuration was saved in a file as stated above, the |
| 570 | previous session id shall be used to reconstruct the file name. |
| 571 | |
| 572 | The session id Emacs has while it is running is in the variable |
| 573 | `x-session-id'. The value of this variable and `x-session-id' may be the |
| 574 | same, depending on how the session manager works. |
| 575 | |
| 576 | See also `emacs-save-session-functions', `emacs-session-save' and |
| 577 | `emacs-session-restore'." */); |
| 578 | Vx_session_previous_id = Qnil; |
| 579 | |
| 580 | defsubr (&Shandle_save_session); |
| 581 | } |
| 582 | |
| 583 | #endif /* HAVE_X_SM */ |