1 /* $OpenBSD: spawn.c,v 1.24 2020/05/21 07:24:13 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 if (sc->name != NULL) { 183 w->name = format_single(item, sc->name, c, s, NULL, 184 NULL); 185 options_set_number(w->options, "automatic-rename", 0); 186 } else 187 w->name = xstrdup(default_window_name(w)); 188 } 189 190 /* Switch to the new window if required. */ 191 if (~sc->flags & SPAWN_DETACHED) 192 session_select(s, sc->wl->idx); 193 194 /* Fire notification if new window. */ 195 if (~sc->flags & SPAWN_RESPAWN) 196 notify_session_window("window-linked", s, w); 197 198 session_group_synchronize_from(s); 199 return (sc->wl); 200 } 201 202 struct window_pane * 203 spawn_pane(struct spawn_context *sc, char **cause) 204 { 205 struct cmdq_item *item = sc->item; 206 struct cmd_find_state *target = cmdq_get_target(item); 207 struct client *c = cmdq_get_client(item); 208 struct session *s = sc->s; 209 struct window *w = sc->wl->window; 210 struct window_pane *new_wp; 211 struct environ *child; 212 struct environ_entry *ee; 213 char **argv, *cp, **argvp, *argv0, *cwd; 214 const char *cmd, *tmp; 215 int argc; 216 u_int idx; 217 struct termios now; 218 u_int hlimit; 219 struct winsize ws; 220 sigset_t set, oldset; 221 key_code key; 222 223 spawn_log(__func__, sc); 224 225 /* 226 * Work out the current working directory. If respawning, use 227 * the pane's stored one unless specified. 228 */ 229 if (sc->cwd != NULL) 230 cwd = format_single(item, sc->cwd, c, target->s, NULL, NULL); 231 else if (~sc->flags & SPAWN_RESPAWN) 232 cwd = xstrdup(server_client_get_cwd(c, target->s)); 233 else 234 cwd = NULL; 235 236 /* 237 * If we are respawning then get rid of the old process. Otherwise 238 * either create a new cell or assign to the one we are given. 239 */ 240 hlimit = options_get_number(s->options, "history-limit"); 241 if (sc->flags & SPAWN_RESPAWN) { 242 if (sc->wp0->fd != -1 && (~sc->flags & SPAWN_KILL)) { 243 window_pane_index(sc->wp0, &idx); 244 xasprintf(cause, "pane %s:%d.%u still active", 245 s->name, sc->wl->idx, idx); 246 free(cwd); 247 return (NULL); 248 } 249 if (sc->wp0->fd != -1) { 250 bufferevent_free(sc->wp0->event); 251 close(sc->wp0->fd); 252 } 253 window_pane_reset_mode_all(sc->wp0); 254 screen_reinit(&sc->wp0->base); 255 input_free(sc->wp0->ictx); 256 sc->wp0->ictx = NULL; 257 new_wp = sc->wp0; 258 new_wp->flags &= ~(PANE_STATUSREADY|PANE_STATUSDRAWN); 259 } else if (sc->lc == NULL) { 260 new_wp = window_add_pane(w, NULL, hlimit, sc->flags); 261 layout_init(w, new_wp); 262 } else { 263 new_wp = window_add_pane(w, sc->wp0, hlimit, sc->flags); 264 layout_assign_pane(sc->lc, new_wp); 265 } 266 267 /* 268 * Now we have a pane with nothing running in it ready for the new process. 269 * Work out the command and arguments and store the working directory. 270 */ 271 if (sc->argc == 0 && (~sc->flags & SPAWN_RESPAWN)) { 272 cmd = options_get_string(s->options, "default-command"); 273 if (cmd != NULL && *cmd != '\0') { 274 argc = 1; 275 argv = (char **)&cmd; 276 } else { 277 argc = 0; 278 argv = NULL; 279 } 280 } else { 281 argc = sc->argc; 282 argv = sc->argv; 283 } 284 if (cwd != NULL) { 285 free(new_wp->cwd); 286 new_wp->cwd = cwd; 287 } 288 289 /* 290 * Replace the stored arguments if there are new ones. If not, the 291 * existing ones will be used (they will only exist for respawn). 292 */ 293 if (argc > 0) { 294 cmd_free_argv(new_wp->argc, new_wp->argv); 295 new_wp->argc = argc; 296 new_wp->argv = cmd_copy_argv(argc, argv); 297 } 298 299 /* Create an environment for this pane. */ 300 child = environ_for_session(s, 0); 301 if (sc->environ != NULL) 302 environ_copy(sc->environ, child); 303 environ_set(child, "TMUX_PANE", 0, "%%%u", new_wp->id); 304 305 /* 306 * Then the PATH environment variable. The session one is replaced from 307 * the client if there is one because otherwise running "tmux new 308 * myprogram" wouldn't work if myprogram isn't in the session's path. 309 */ 310 if (c != NULL && c->session == NULL) { /* only unattached clients */ 311 ee = environ_find(c->environ, "PATH"); 312 if (ee != NULL) 313 environ_set(child, "PATH", 0, "%s", ee->value); 314 } 315 if (environ_find(child, "PATH") == NULL) 316 environ_set(child, "PATH", 0, "%s", _PATH_DEFPATH); 317 318 /* Then the shell. If respawning, use the old one. */ 319 if (~sc->flags & SPAWN_RESPAWN) { 320 tmp = options_get_string(s->options, "default-shell"); 321 if (!checkshell(tmp)) 322 tmp = _PATH_BSHELL; 323 free(new_wp->shell); 324 new_wp->shell = xstrdup(tmp); 325 } 326 environ_set(child, "SHELL", 0, "%s", new_wp->shell); 327 328 /* Log the arguments we are going to use. */ 329 log_debug("%s: shell=%s", __func__, new_wp->shell); 330 if (new_wp->argc != 0) { 331 cp = cmd_stringify_argv(new_wp->argc, new_wp->argv); 332 log_debug("%s: cmd=%s", __func__, cp); 333 free(cp); 334 } 335 if (cwd != NULL) 336 log_debug("%s: cwd=%s", __func__, cwd); 337 cmd_log_argv(new_wp->argc, new_wp->argv, "%s", __func__); 338 environ_log(child, "%s: environment ", __func__); 339 340 /* Initialize the window size. */ 341 memset(&ws, 0, sizeof ws); 342 ws.ws_col = screen_size_x(&new_wp->base); 343 ws.ws_row = screen_size_y(&new_wp->base); 344 ws.ws_xpixel = w->xpixel * ws.ws_col; 345 ws.ws_ypixel = w->ypixel * ws.ws_row; 346 347 /* Block signals until fork has completed. */ 348 sigfillset(&set); 349 sigprocmask(SIG_BLOCK, &set, &oldset); 350 351 /* If the command is empty, don't fork a child process. */ 352 if (sc->flags & SPAWN_EMPTY) { 353 new_wp->flags |= PANE_EMPTY; 354 new_wp->base.mode &= ~MODE_CURSOR; 355 new_wp->base.mode |= MODE_CRLF; 356 goto complete; 357 } 358 359 /* Fork the new process. */ 360 new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws); 361 if (new_wp->pid == -1) { 362 xasprintf(cause, "fork failed: %s", strerror(errno)); 363 new_wp->fd = -1; 364 if (~sc->flags & SPAWN_RESPAWN) { 365 server_client_remove_pane(new_wp); 366 layout_close_pane(new_wp); 367 window_remove_pane(w, new_wp); 368 } 369 sigprocmask(SIG_SETMASK, &oldset, NULL); 370 environ_free(child); 371 return (NULL); 372 } 373 374 /* In the parent process, everything is done now. */ 375 if (new_wp->pid != 0) 376 goto complete; 377 378 /* 379 * Child process. Change to the working directory or home if that 380 * fails. 381 */ 382 if (chdir(new_wp->cwd) != 0) { 383 if ((tmp = find_home()) == NULL || chdir(tmp) != 0) 384 chdir("/"); 385 } 386 387 /* 388 * Update terminal escape characters from the session if available and 389 * force VERASE to tmux's backspace. 390 */ 391 if (tcgetattr(STDIN_FILENO, &now) != 0) 392 _exit(1); 393 if (s->tio != NULL) 394 memcpy(now.c_cc, s->tio->c_cc, sizeof now.c_cc); 395 key = options_get_number(global_options, "backspace"); 396 if (key >= 0x7f) 397 now.c_cc[VERASE] = '\177'; 398 else 399 now.c_cc[VERASE] = key; 400 if (tcsetattr(STDIN_FILENO, TCSANOW, &now) != 0) 401 _exit(1); 402 403 /* Clean up file descriptors and signals and update the environment. */ 404 closefrom(STDERR_FILENO + 1); 405 proc_clear_signals(server_proc, 1); 406 sigprocmask(SIG_SETMASK, &oldset, NULL); 407 log_close(); 408 environ_push(child); 409 410 /* 411 * If given multiple arguments, use execvp(). Copy the arguments to 412 * ensure they end in a NULL. 413 */ 414 if (new_wp->argc != 0 && new_wp->argc != 1) { 415 argvp = cmd_copy_argv(new_wp->argc, new_wp->argv); 416 execvp(argvp[0], argvp); 417 _exit(1); 418 } 419 420 /* 421 * If one argument, pass it to $SHELL -c. Otherwise create a login 422 * shell. 423 */ 424 cp = strrchr(new_wp->shell, '/'); 425 if (new_wp->argc == 1) { 426 tmp = new_wp->argv[0]; 427 if (cp != NULL && cp[1] != '\0') 428 xasprintf(&argv0, "%s", cp + 1); 429 else 430 xasprintf(&argv0, "%s", new_wp->shell); 431 execl(new_wp->shell, argv0, "-c", tmp, (char *)NULL); 432 _exit(1); 433 } 434 if (cp != NULL && cp[1] != '\0') 435 xasprintf(&argv0, "-%s", cp + 1); 436 else 437 xasprintf(&argv0, "-%s", new_wp->shell); 438 execl(new_wp->shell, argv0, (char *)NULL); 439 _exit(1); 440 441 complete: 442 new_wp->flags &= ~PANE_EXITED; 443 444 sigprocmask(SIG_SETMASK, &oldset, NULL); 445 window_pane_set_event(new_wp); 446 447 environ_free(child); 448 449 if (sc->flags & SPAWN_RESPAWN) 450 return (new_wp); 451 if ((~sc->flags & SPAWN_DETACHED) || w->active == NULL) { 452 if (sc->flags & SPAWN_NONOTIFY) 453 window_set_active_pane(w, new_wp, 0); 454 else 455 window_set_active_pane(w, new_wp, 1); 456 } 457 if (~sc->flags & SPAWN_NONOTIFY) 458 notify_window("window-layout-changed", w); 459 return (new_wp); 460 } 461