1 /* $OpenBSD: spawn.c,v 1.29 2021/08/23 11:04:21 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 window_set_active_pane(w, sc->wp0, 0); 119 } 120 121 /* 122 * Otherwise we have no window so we will need to create one. First 123 * check if the given index already exists and destroy it if so. 124 */ 125 if ((~sc->flags & SPAWN_RESPAWN) && idx != -1) { 126 wl = winlink_find_by_index(&s->windows, idx); 127 if (wl != NULL && (~sc->flags & SPAWN_KILL)) { 128 xasprintf(cause, "index %d in use", idx); 129 return (NULL); 130 } 131 if (wl != NULL) { 132 /* 133 * Can't use session_detach as it will destroy session 134 * if this makes it empty. 135 */ 136 wl->flags &= ~WINLINK_ALERTFLAGS; 137 notify_session_window("window-unlinked", s, wl->window); 138 winlink_stack_remove(&s->lastw, wl); 139 winlink_remove(&s->windows, wl); 140 141 if (s->curw == wl) { 142 s->curw = NULL; 143 sc->flags &= ~SPAWN_DETACHED; 144 } 145 } 146 } 147 148 /* Then create a window if needed. */ 149 if (~sc->flags & SPAWN_RESPAWN) { 150 if (idx == -1) 151 idx = -1 - options_get_number(s->options, "base-index"); 152 if ((sc->wl = winlink_add(&s->windows, idx)) == NULL) { 153 xasprintf(cause, "couldn't add window %d", idx); 154 return (NULL); 155 } 156 default_window_size(sc->tc, s, NULL, &sx, &sy, &xpixel, &ypixel, 157 -1); 158 if ((w = window_create(sx, sy, xpixel, ypixel)) == NULL) { 159 winlink_remove(&s->windows, sc->wl); 160 xasprintf(cause, "couldn't create window %d", idx); 161 return (NULL); 162 } 163 if (s->curw == NULL) 164 s->curw = sc->wl; 165 sc->wl->session = s; 166 w->latest = sc->tc; 167 winlink_set_window(sc->wl, w); 168 } else 169 w = NULL; 170 sc->flags |= SPAWN_NONOTIFY; 171 172 /* Spawn the pane. */ 173 wp = spawn_pane(sc, cause); 174 if (wp == NULL) { 175 if (~sc->flags & SPAWN_RESPAWN) 176 winlink_remove(&s->windows, sc->wl); 177 return (NULL); 178 } 179 180 /* Set the name of the new window. */ 181 if (~sc->flags & SPAWN_RESPAWN) { 182 free(w->name); 183 if (sc->name != NULL) { 184 w->name = format_single(item, sc->name, c, s, NULL, 185 NULL); 186 options_set_number(w->options, "automatic-rename", 0); 187 } else 188 w->name = default_window_name(w); 189 } 190 191 /* Switch to the new window if required. */ 192 if (~sc->flags & SPAWN_DETACHED) 193 session_select(s, sc->wl->idx); 194 195 /* Fire notification if new window. */ 196 if (~sc->flags & SPAWN_RESPAWN) 197 notify_session_window("window-linked", s, w); 198 199 session_group_synchronize_from(s); 200 return (sc->wl); 201 } 202 203 struct window_pane * 204 spawn_pane(struct spawn_context *sc, char **cause) 205 { 206 struct cmdq_item *item = sc->item; 207 struct cmd_find_state *target = cmdq_get_target(item); 208 struct client *c = cmdq_get_client(item); 209 struct session *s = sc->s; 210 struct window *w = sc->wl->window; 211 struct window_pane *new_wp; 212 struct environ *child; 213 struct environ_entry *ee; 214 char **argv, *cp, **argvp, *argv0, *cwd; 215 const char *cmd, *tmp; 216 int argc; 217 u_int idx; 218 struct termios now; 219 u_int hlimit; 220 struct winsize ws; 221 sigset_t set, oldset; 222 key_code key; 223 224 spawn_log(__func__, sc); 225 226 /* 227 * Work out the current working directory. If respawning, use 228 * the pane's stored one unless specified. 229 */ 230 if (sc->cwd != NULL) 231 cwd = format_single(item, sc->cwd, c, target->s, NULL, NULL); 232 else if (~sc->flags & SPAWN_RESPAWN) 233 cwd = xstrdup(server_client_get_cwd(c, target->s)); 234 else 235 cwd = NULL; 236 237 /* 238 * If we are respawning then get rid of the old process. Otherwise 239 * either create a new cell or assign to the one we are given. 240 */ 241 hlimit = options_get_number(s->options, "history-limit"); 242 if (sc->flags & SPAWN_RESPAWN) { 243 if (sc->wp0->fd != -1 && (~sc->flags & SPAWN_KILL)) { 244 window_pane_index(sc->wp0, &idx); 245 xasprintf(cause, "pane %s:%d.%u still active", 246 s->name, sc->wl->idx, idx); 247 free(cwd); 248 return (NULL); 249 } 250 if (sc->wp0->fd != -1) { 251 bufferevent_free(sc->wp0->event); 252 close(sc->wp0->fd); 253 } 254 window_pane_reset_mode_all(sc->wp0); 255 screen_reinit(&sc->wp0->base); 256 input_free(sc->wp0->ictx); 257 sc->wp0->ictx = NULL; 258 new_wp = sc->wp0; 259 new_wp->flags &= ~(PANE_STATUSREADY|PANE_STATUSDRAWN); 260 } else if (sc->lc == NULL) { 261 new_wp = window_add_pane(w, NULL, hlimit, sc->flags); 262 layout_init(w, new_wp); 263 } else { 264 new_wp = window_add_pane(w, sc->wp0, hlimit, sc->flags); 265 if (sc->flags & SPAWN_ZOOM) 266 layout_assign_pane(sc->lc, new_wp, 1); 267 else 268 layout_assign_pane(sc->lc, new_wp, 0); 269 } 270 271 /* 272 * Now we have a pane with nothing running in it ready for the new 273 * process. Work out the command and arguments and store the working 274 * directory. 275 */ 276 if (sc->argc == 0 && (~sc->flags & SPAWN_RESPAWN)) { 277 cmd = options_get_string(s->options, "default-command"); 278 if (cmd != NULL && *cmd != '\0') { 279 argc = 1; 280 argv = (char **)&cmd; 281 } else { 282 argc = 0; 283 argv = NULL; 284 } 285 } else { 286 argc = sc->argc; 287 argv = sc->argv; 288 } 289 if (cwd != NULL) { 290 free(new_wp->cwd); 291 new_wp->cwd = cwd; 292 } 293 294 /* 295 * Replace the stored arguments if there are new ones. If not, the 296 * existing ones will be used (they will only exist for respawn). 297 */ 298 if (argc > 0) { 299 cmd_free_argv(new_wp->argc, new_wp->argv); 300 new_wp->argc = argc; 301 new_wp->argv = cmd_copy_argv(argc, argv); 302 } 303 304 /* Create an environment for this pane. */ 305 child = environ_for_session(s, 0); 306 if (sc->environ != NULL) 307 environ_copy(sc->environ, child); 308 environ_set(child, "TMUX_PANE", 0, "%%%u", new_wp->id); 309 310 /* 311 * Then the PATH environment variable. The session one is replaced from 312 * the client if there is one because otherwise running "tmux new 313 * myprogram" wouldn't work if myprogram isn't in the session's path. 314 */ 315 if (c != NULL && c->session == NULL) { /* only unattached clients */ 316 ee = environ_find(c->environ, "PATH"); 317 if (ee != NULL) 318 environ_set(child, "PATH", 0, "%s", ee->value); 319 } 320 if (environ_find(child, "PATH") == NULL) 321 environ_set(child, "PATH", 0, "%s", _PATH_DEFPATH); 322 323 /* Then the shell. If respawning, use the old one. */ 324 if (~sc->flags & SPAWN_RESPAWN) { 325 tmp = options_get_string(s->options, "default-shell"); 326 if (!checkshell(tmp)) 327 tmp = _PATH_BSHELL; 328 free(new_wp->shell); 329 new_wp->shell = xstrdup(tmp); 330 } 331 environ_set(child, "SHELL", 0, "%s", new_wp->shell); 332 333 /* Log the arguments we are going to use. */ 334 log_debug("%s: shell=%s", __func__, new_wp->shell); 335 if (new_wp->argc != 0) { 336 cp = cmd_stringify_argv(new_wp->argc, new_wp->argv); 337 log_debug("%s: cmd=%s", __func__, cp); 338 free(cp); 339 } 340 if (cwd != NULL) 341 log_debug("%s: cwd=%s", __func__, cwd); 342 cmd_log_argv(new_wp->argc, new_wp->argv, "%s", __func__); 343 environ_log(child, "%s: environment ", __func__); 344 345 /* Initialize the window size. */ 346 memset(&ws, 0, sizeof ws); 347 ws.ws_col = screen_size_x(&new_wp->base); 348 ws.ws_row = screen_size_y(&new_wp->base); 349 ws.ws_xpixel = w->xpixel * ws.ws_col; 350 ws.ws_ypixel = w->ypixel * ws.ws_row; 351 352 /* Block signals until fork has completed. */ 353 sigfillset(&set); 354 sigprocmask(SIG_BLOCK, &set, &oldset); 355 356 /* If the command is empty, don't fork a child process. */ 357 if (sc->flags & SPAWN_EMPTY) { 358 new_wp->flags |= PANE_EMPTY; 359 new_wp->base.mode &= ~MODE_CURSOR; 360 new_wp->base.mode |= MODE_CRLF; 361 goto complete; 362 } 363 364 /* Fork the new process. */ 365 new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws); 366 if (new_wp->pid == -1) { 367 xasprintf(cause, "fork failed: %s", strerror(errno)); 368 new_wp->fd = -1; 369 if (~sc->flags & SPAWN_RESPAWN) { 370 server_client_remove_pane(new_wp); 371 layout_close_pane(new_wp); 372 window_remove_pane(w, new_wp); 373 } 374 sigprocmask(SIG_SETMASK, &oldset, NULL); 375 environ_free(child); 376 return (NULL); 377 } 378 379 /* In the parent process, everything is done now. */ 380 if (new_wp->pid != 0) 381 goto complete; 382 383 /* 384 * Child process. Change to the working directory or home if that 385 * fails. 386 */ 387 if (chdir(new_wp->cwd) != 0 && 388 ((tmp = find_home()) == NULL || chdir(tmp) != 0) && 389 chdir("/") != 0) 390 fatal("chdir failed"); 391 392 /* 393 * Update terminal escape characters from the session if available and 394 * force VERASE to tmux's backspace. 395 */ 396 if (tcgetattr(STDIN_FILENO, &now) != 0) 397 _exit(1); 398 if (s->tio != NULL) 399 memcpy(now.c_cc, s->tio->c_cc, sizeof now.c_cc); 400 key = options_get_number(global_options, "backspace"); 401 if (key >= 0x7f) 402 now.c_cc[VERASE] = '\177'; 403 else 404 now.c_cc[VERASE] = key; 405 if (tcsetattr(STDIN_FILENO, TCSANOW, &now) != 0) 406 _exit(1); 407 408 /* Clean up file descriptors and signals and update the environment. */ 409 closefrom(STDERR_FILENO + 1); 410 proc_clear_signals(server_proc, 1); 411 sigprocmask(SIG_SETMASK, &oldset, NULL); 412 log_close(); 413 environ_push(child); 414 415 /* 416 * If given multiple arguments, use execvp(). Copy the arguments to 417 * ensure they end in a NULL. 418 */ 419 if (new_wp->argc != 0 && new_wp->argc != 1) { 420 argvp = cmd_copy_argv(new_wp->argc, new_wp->argv); 421 execvp(argvp[0], argvp); 422 _exit(1); 423 } 424 425 /* 426 * If one argument, pass it to $SHELL -c. Otherwise create a login 427 * shell. 428 */ 429 cp = strrchr(new_wp->shell, '/'); 430 if (new_wp->argc == 1) { 431 tmp = new_wp->argv[0]; 432 if (cp != NULL && cp[1] != '\0') 433 xasprintf(&argv0, "%s", cp + 1); 434 else 435 xasprintf(&argv0, "%s", new_wp->shell); 436 execl(new_wp->shell, argv0, "-c", tmp, (char *)NULL); 437 _exit(1); 438 } 439 if (cp != NULL && cp[1] != '\0') 440 xasprintf(&argv0, "-%s", cp + 1); 441 else 442 xasprintf(&argv0, "-%s", new_wp->shell); 443 execl(new_wp->shell, argv0, (char *)NULL); 444 _exit(1); 445 446 complete: 447 new_wp->flags &= ~PANE_EXITED; 448 449 sigprocmask(SIG_SETMASK, &oldset, NULL); 450 window_pane_set_event(new_wp); 451 452 environ_free(child); 453 454 if (sc->flags & SPAWN_RESPAWN) 455 return (new_wp); 456 if ((~sc->flags & SPAWN_DETACHED) || w->active == NULL) { 457 if (sc->flags & SPAWN_NONOTIFY) 458 window_set_active_pane(w, new_wp, 0); 459 else 460 window_set_active_pane(w, new_wp, 1); 461 } 462 if (~sc->flags & SPAWN_NONOTIFY) 463 notify_window("window-layout-changed", w); 464 return (new_wp); 465 } 466