1 /* $OpenBSD: spawn.c,v 1.33 2023/07/10 09:24:53 nicm Exp $ */ 2 3 /* 4 * Copyright (c) 2019 Nicholas Marriott <nicholas.marriott@gmail.com> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER 15 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING 16 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/types.h> 20 21 #include <errno.h> 22 #include <paths.h> 23 #include <signal.h> 24 #include <stdlib.h> 25 #include <string.h> 26 #include <unistd.h> 27 #include <util.h> 28 29 #include "tmux.h" 30 31 /* 32 * Set up the environment and create a new window and pane or a new pane. 33 * 34 * We need to set up the following items: 35 * 36 * - history limit, comes from the session; 37 * 38 * - base index, comes from the session; 39 * 40 * - current working directory, may be specified - if it isn't it comes from 41 * either the client or the session; 42 * 43 * - PATH variable, comes from the client if any, otherwise from the session 44 * environment; 45 * 46 * - shell, comes from default-shell; 47 * 48 * - termios, comes from the session; 49 * 50 * - remaining environment, comes from the session. 51 */ 52 53 static void 54 spawn_log(const char *from, struct spawn_context *sc) 55 { 56 struct session *s = sc->s; 57 struct winlink *wl = sc->wl; 58 struct window_pane *wp0 = sc->wp0; 59 const char *name = cmdq_get_name(sc->item); 60 char tmp[128]; 61 62 log_debug("%s: %s, flags=%#x", from, name, sc->flags); 63 64 if (wl != NULL && wp0 != NULL) 65 xsnprintf(tmp, sizeof tmp, "wl=%d wp0=%%%u", wl->idx, wp0->id); 66 else if (wl != NULL) 67 xsnprintf(tmp, sizeof tmp, "wl=%d wp0=none", wl->idx); 68 else if (wp0 != NULL) 69 xsnprintf(tmp, sizeof tmp, "wl=none wp0=%%%u", wp0->id); 70 else 71 xsnprintf(tmp, sizeof tmp, "wl=none wp0=none"); 72 log_debug("%s: s=$%u %s idx=%d", from, s->id, tmp, sc->idx); 73 log_debug("%s: name=%s", from, sc->name == NULL ? "none" : sc->name); 74 } 75 76 struct winlink * 77 spawn_window(struct spawn_context *sc, char **cause) 78 { 79 struct cmdq_item *item = sc->item; 80 struct client *c = cmdq_get_client(item); 81 struct session *s = sc->s; 82 struct window *w; 83 struct window_pane *wp; 84 struct winlink *wl; 85 int idx = sc->idx; 86 u_int sx, sy, xpixel, ypixel; 87 88 spawn_log(__func__, sc); 89 90 /* 91 * If the window already exists, we are respawning, so destroy all the 92 * panes except one. 93 */ 94 if (sc->flags & SPAWN_RESPAWN) { 95 w = sc->wl->window; 96 if (~sc->flags & SPAWN_KILL) { 97 TAILQ_FOREACH(wp, &w->panes, entry) { 98 if (wp->fd != -1) 99 break; 100 } 101 if (wp != NULL) { 102 xasprintf(cause, "window %s:%d still active", 103 s->name, sc->wl->idx); 104 return (NULL); 105 } 106 } 107 108 sc->wp0 = TAILQ_FIRST(&w->panes); 109 TAILQ_REMOVE(&w->panes, sc->wp0, entry); 110 111 layout_free(w); 112 window_destroy_panes(w); 113 114 TAILQ_INSERT_HEAD(&w->panes, sc->wp0, entry); 115 window_pane_resize(sc->wp0, w->sx, w->sy); 116 117 layout_init(w, sc->wp0); 118 w->active = NULL; 119 window_set_active_pane(w, sc->wp0, 0); 120 } 121 122 /* 123 * Otherwise we have no window so we will need to create one. First 124 * check if the given index already exists and destroy it if so. 125 */ 126 if ((~sc->flags & SPAWN_RESPAWN) && idx != -1) { 127 wl = winlink_find_by_index(&s->windows, idx); 128 if (wl != NULL && (~sc->flags & SPAWN_KILL)) { 129 xasprintf(cause, "index %d in use", idx); 130 return (NULL); 131 } 132 if (wl != NULL) { 133 /* 134 * Can't use session_detach as it will destroy session 135 * if this makes it empty. 136 */ 137 wl->flags &= ~WINLINK_ALERTFLAGS; 138 notify_session_window("window-unlinked", s, wl->window); 139 winlink_stack_remove(&s->lastw, wl); 140 winlink_remove(&s->windows, wl); 141 142 if (s->curw == wl) { 143 s->curw = NULL; 144 sc->flags &= ~SPAWN_DETACHED; 145 } 146 } 147 } 148 149 /* Then create a window if needed. */ 150 if (~sc->flags & SPAWN_RESPAWN) { 151 if (idx == -1) 152 idx = -1 - options_get_number(s->options, "base-index"); 153 if ((sc->wl = winlink_add(&s->windows, idx)) == NULL) { 154 xasprintf(cause, "couldn't add window %d", idx); 155 return (NULL); 156 } 157 default_window_size(sc->tc, s, NULL, &sx, &sy, &xpixel, &ypixel, 158 -1); 159 if ((w = window_create(sx, sy, xpixel, ypixel)) == NULL) { 160 winlink_remove(&s->windows, sc->wl); 161 xasprintf(cause, "couldn't create window %d", idx); 162 return (NULL); 163 } 164 if (s->curw == NULL) 165 s->curw = sc->wl; 166 sc->wl->session = s; 167 w->latest = sc->tc; 168 winlink_set_window(sc->wl, w); 169 } else 170 w = NULL; 171 sc->flags |= SPAWN_NONOTIFY; 172 173 /* Spawn the pane. */ 174 wp = spawn_pane(sc, cause); 175 if (wp == NULL) { 176 if (~sc->flags & SPAWN_RESPAWN) 177 winlink_remove(&s->windows, sc->wl); 178 return (NULL); 179 } 180 181 /* Set the name of the new window. */ 182 if (~sc->flags & SPAWN_RESPAWN) { 183 free(w->name); 184 if (sc->name != NULL) { 185 w->name = format_single(item, sc->name, c, s, NULL, 186 NULL); 187 options_set_number(w->options, "automatic-rename", 0); 188 } else 189 w->name = default_window_name(w); 190 } 191 192 /* Switch to the new window if required. */ 193 if (~sc->flags & SPAWN_DETACHED) 194 session_select(s, sc->wl->idx); 195 196 /* Fire notification if new window. */ 197 if (~sc->flags & SPAWN_RESPAWN) 198 notify_session_window("window-linked", s, w); 199 200 session_group_synchronize_from(s); 201 return (sc->wl); 202 } 203 204 struct window_pane * 205 spawn_pane(struct spawn_context *sc, char **cause) 206 { 207 struct cmdq_item *item = sc->item; 208 struct cmd_find_state *target = cmdq_get_target(item); 209 struct client *c = cmdq_get_client(item); 210 struct session *s = sc->s; 211 struct window *w = sc->wl->window; 212 struct window_pane *new_wp; 213 struct environ *child; 214 struct environ_entry *ee; 215 char **argv, *cp, **argvp, *argv0, *cwd, *new_cwd; 216 const char *cmd, *tmp; 217 int argc; 218 u_int idx; 219 struct termios now; 220 u_int hlimit; 221 struct winsize ws; 222 sigset_t set, oldset; 223 key_code key; 224 225 spawn_log(__func__, sc); 226 227 /* 228 * Work out the current working directory. If respawning, use 229 * the pane's stored one unless specified. 230 */ 231 if (sc->cwd != NULL) { 232 cwd = format_single(item, sc->cwd, c, target->s, NULL, NULL); 233 if (*cwd != '/') { 234 xasprintf(&new_cwd, "%s/%s", server_client_get_cwd(c, 235 target->s), cwd); 236 free(cwd); 237 cwd = new_cwd; 238 } 239 } else if (~sc->flags & SPAWN_RESPAWN) 240 cwd = xstrdup(server_client_get_cwd(c, target->s)); 241 else 242 cwd = NULL; 243 244 /* 245 * If we are respawning then get rid of the old process. Otherwise 246 * either create a new cell or assign to the one we are given. 247 */ 248 hlimit = options_get_number(s->options, "history-limit"); 249 if (sc->flags & SPAWN_RESPAWN) { 250 if (sc->wp0->fd != -1 && (~sc->flags & SPAWN_KILL)) { 251 window_pane_index(sc->wp0, &idx); 252 xasprintf(cause, "pane %s:%d.%u still active", 253 s->name, sc->wl->idx, idx); 254 free(cwd); 255 return (NULL); 256 } 257 if (sc->wp0->fd != -1) { 258 bufferevent_free(sc->wp0->event); 259 close(sc->wp0->fd); 260 } 261 window_pane_reset_mode_all(sc->wp0); 262 screen_reinit(&sc->wp0->base); 263 input_free(sc->wp0->ictx); 264 sc->wp0->ictx = NULL; 265 new_wp = sc->wp0; 266 new_wp->flags &= ~(PANE_STATUSREADY|PANE_STATUSDRAWN); 267 } else if (sc->lc == NULL) { 268 new_wp = window_add_pane(w, NULL, hlimit, sc->flags); 269 layout_init(w, new_wp); 270 } else { 271 new_wp = window_add_pane(w, sc->wp0, hlimit, sc->flags); 272 if (sc->flags & SPAWN_ZOOM) 273 layout_assign_pane(sc->lc, new_wp, 1); 274 else 275 layout_assign_pane(sc->lc, new_wp, 0); 276 } 277 278 /* 279 * Now we have a pane with nothing running in it ready for the new 280 * process. Work out the command and arguments and store the working 281 * directory. 282 */ 283 if (sc->argc == 0 && (~sc->flags & SPAWN_RESPAWN)) { 284 cmd = options_get_string(s->options, "default-command"); 285 if (cmd != NULL && *cmd != '\0') { 286 argc = 1; 287 argv = (char **)&cmd; 288 } else { 289 argc = 0; 290 argv = NULL; 291 } 292 } else { 293 argc = sc->argc; 294 argv = sc->argv; 295 } 296 if (cwd != NULL) { 297 free(new_wp->cwd); 298 new_wp->cwd = cwd; 299 } 300 301 /* 302 * Replace the stored arguments if there are new ones. If not, the 303 * existing ones will be used (they will only exist for respawn). 304 */ 305 if (argc > 0) { 306 cmd_free_argv(new_wp->argc, new_wp->argv); 307 new_wp->argc = argc; 308 new_wp->argv = cmd_copy_argv(argc, argv); 309 } 310 311 /* Create an environment for this pane. */ 312 child = environ_for_session(s, 0); 313 if (sc->environ != NULL) 314 environ_copy(sc->environ, child); 315 environ_set(child, "TMUX_PANE", 0, "%%%u", new_wp->id); 316 317 /* 318 * Then the PATH environment variable. The session one is replaced from 319 * the client if there is one because otherwise running "tmux new 320 * myprogram" wouldn't work if myprogram isn't in the session's path. 321 */ 322 if (c != NULL && c->session == NULL) { /* only unattached clients */ 323 ee = environ_find(c->environ, "PATH"); 324 if (ee != NULL) 325 environ_set(child, "PATH", 0, "%s", ee->value); 326 } 327 if (environ_find(child, "PATH") == NULL) 328 environ_set(child, "PATH", 0, "%s", _PATH_DEFPATH); 329 330 /* Then the shell. If respawning, use the old one. */ 331 if (~sc->flags & SPAWN_RESPAWN) { 332 tmp = options_get_string(s->options, "default-shell"); 333 if (!checkshell(tmp)) 334 tmp = _PATH_BSHELL; 335 free(new_wp->shell); 336 new_wp->shell = xstrdup(tmp); 337 } 338 environ_set(child, "SHELL", 0, "%s", new_wp->shell); 339 340 /* Log the arguments we are going to use. */ 341 log_debug("%s: shell=%s", __func__, new_wp->shell); 342 if (new_wp->argc != 0) { 343 cp = cmd_stringify_argv(new_wp->argc, new_wp->argv); 344 log_debug("%s: cmd=%s", __func__, cp); 345 free(cp); 346 } 347 log_debug("%s: cwd=%s", __func__, new_wp->cwd); 348 cmd_log_argv(new_wp->argc, new_wp->argv, "%s", __func__); 349 environ_log(child, "%s: environment ", __func__); 350 351 /* Initialize the window size. */ 352 memset(&ws, 0, sizeof ws); 353 ws.ws_col = screen_size_x(&new_wp->base); 354 ws.ws_row = screen_size_y(&new_wp->base); 355 ws.ws_xpixel = w->xpixel * ws.ws_col; 356 ws.ws_ypixel = w->ypixel * ws.ws_row; 357 358 /* Block signals until fork has completed. */ 359 sigfillset(&set); 360 sigprocmask(SIG_BLOCK, &set, &oldset); 361 362 /* If the command is empty, don't fork a child process. */ 363 if (sc->flags & SPAWN_EMPTY) { 364 new_wp->flags |= PANE_EMPTY; 365 new_wp->base.mode &= ~MODE_CURSOR; 366 new_wp->base.mode |= MODE_CRLF; 367 goto complete; 368 } 369 370 /* Fork the new process. */ 371 new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws); 372 if (new_wp->pid == -1) { 373 xasprintf(cause, "fork failed: %s", strerror(errno)); 374 new_wp->fd = -1; 375 if (~sc->flags & SPAWN_RESPAWN) { 376 server_client_remove_pane(new_wp); 377 layout_close_pane(new_wp); 378 window_remove_pane(w, new_wp); 379 } 380 sigprocmask(SIG_SETMASK, &oldset, NULL); 381 environ_free(child); 382 return (NULL); 383 } 384 385 /* In the parent process, everything is done now. */ 386 if (new_wp->pid != 0) 387 goto complete; 388 389 /* 390 * Child process. Change to the working directory or home if that 391 * fails. 392 */ 393 if (chdir(new_wp->cwd) == 0) 394 environ_set(child, "PWD", 0, "%s", new_wp->cwd); 395 else if ((tmp = find_home()) != NULL && chdir(tmp) == 0) 396 environ_set(child, "PWD", 0, "%s", tmp); 397 else if (chdir("/") == 0) 398 environ_set(child, "PWD", 0, "/"); 399 else 400 fatal("chdir failed"); 401 402 /* 403 * Update terminal escape characters from the session if available and 404 * force VERASE to tmux's backspace. 405 */ 406 if (tcgetattr(STDIN_FILENO, &now) != 0) 407 _exit(1); 408 if (s->tio != NULL) 409 memcpy(now.c_cc, s->tio->c_cc, sizeof now.c_cc); 410 key = options_get_number(global_options, "backspace"); 411 if (key >= 0x7f) 412 now.c_cc[VERASE] = '\177'; 413 else 414 now.c_cc[VERASE] = key; 415 if (tcsetattr(STDIN_FILENO, TCSANOW, &now) != 0) 416 _exit(1); 417 418 /* Clean up file descriptors and signals and update the environment. */ 419 proc_clear_signals(server_proc, 1); 420 closefrom(STDERR_FILENO + 1); 421 sigprocmask(SIG_SETMASK, &oldset, NULL); 422 log_close(); 423 environ_push(child); 424 425 /* 426 * If given multiple arguments, use execvp(). Copy the arguments to 427 * ensure they end in a NULL. 428 */ 429 if (new_wp->argc != 0 && new_wp->argc != 1) { 430 argvp = cmd_copy_argv(new_wp->argc, new_wp->argv); 431 execvp(argvp[0], argvp); 432 _exit(1); 433 } 434 435 /* 436 * If one argument, pass it to $SHELL -c. Otherwise create a login 437 * shell. 438 */ 439 cp = strrchr(new_wp->shell, '/'); 440 if (new_wp->argc == 1) { 441 tmp = new_wp->argv[0]; 442 if (cp != NULL && cp[1] != '\0') 443 xasprintf(&argv0, "%s", cp + 1); 444 else 445 xasprintf(&argv0, "%s", new_wp->shell); 446 execl(new_wp->shell, argv0, "-c", tmp, (char *)NULL); 447 _exit(1); 448 } 449 if (cp != NULL && cp[1] != '\0') 450 xasprintf(&argv0, "-%s", cp + 1); 451 else 452 xasprintf(&argv0, "-%s", new_wp->shell); 453 execl(new_wp->shell, argv0, (char *)NULL); 454 _exit(1); 455 456 complete: 457 new_wp->flags &= ~PANE_EXITED; 458 459 sigprocmask(SIG_SETMASK, &oldset, NULL); 460 window_pane_set_event(new_wp); 461 462 environ_free(child); 463 464 if (sc->flags & SPAWN_RESPAWN) 465 return (new_wp); 466 if ((~sc->flags & SPAWN_DETACHED) || w->active == NULL) { 467 if (sc->flags & SPAWN_NONOTIFY) 468 window_set_active_pane(w, new_wp, 0); 469 else 470 window_set_active_pane(w, new_wp, 1); 471 } 472 if (~sc->flags & SPAWN_NONOTIFY) 473 notify_window("window-layout-changed", w); 474 return (new_wp); 475 } 476