1 /* $OpenBSD: spawn.c,v 1.10 2019/10/07 07:14:07 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 char tmp[128]; 60 const char *name; 61 62 log_debug("%s: %s, flags=%#x", from, sc->item->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 74 name = sc->name; 75 if (name == NULL) 76 name = "none"; 77 log_debug("%s: name=%s", from, name); 78 } 79 80 struct winlink * 81 spawn_window(struct spawn_context *sc, char **cause) 82 { 83 struct session *s = sc->s; 84 struct window *w; 85 struct window_pane *wp; 86 struct winlink *wl; 87 int idx = sc->idx; 88 u_int sx, sy; 89 90 spawn_log(__func__, sc); 91 92 /* 93 * If the window already exists, we are respawning, so destroy all the 94 * panes except one. 95 */ 96 if (sc->flags & SPAWN_RESPAWN) { 97 w = sc->wl->window; 98 if (~sc->flags & SPAWN_KILL) { 99 TAILQ_FOREACH(wp, &w->panes, entry) { 100 if (wp->fd != -1) 101 break; 102 } 103 if (wp != NULL) { 104 xasprintf(cause, "window %s:%d still active", 105 s->name, sc->wl->idx); 106 return (NULL); 107 } 108 } 109 110 sc->wp0 = TAILQ_FIRST(&w->panes); 111 TAILQ_REMOVE(&w->panes, sc->wp0, entry); 112 113 layout_free(w); 114 window_destroy_panes(w); 115 116 TAILQ_INSERT_HEAD(&w->panes, sc->wp0, entry); 117 window_pane_resize(sc->wp0, w->sx, w->sy); 118 119 layout_init(w, sc->wp0); 120 window_set_active_pane(w, sc->wp0, 0); 121 } 122 123 /* 124 * Otherwise we have no window so we will need to create one. First 125 * check if the given index already exists and destroy it if so. 126 */ 127 if ((~sc->flags & SPAWN_RESPAWN) && idx != -1) { 128 wl = winlink_find_by_index(&s->windows, idx); 129 if (wl != NULL && (~sc->flags & SPAWN_KILL)) { 130 xasprintf(cause, "index %d in use", idx); 131 return (NULL); 132 } 133 if (wl != NULL) { 134 /* 135 * Can't use session_detach as it will destroy session 136 * if this makes it empty. 137 */ 138 wl->flags &= ~WINLINK_ALERTFLAGS; 139 notify_session_window("window-unlinked", s, wl->window); 140 winlink_stack_remove(&s->lastw, wl); 141 winlink_remove(&s->windows, wl); 142 143 if (s->curw == wl) { 144 s->curw = NULL; 145 sc->flags &= ~SPAWN_DETACHED; 146 } 147 } 148 } 149 150 /* Then create a window if needed. */ 151 if (~sc->flags & SPAWN_RESPAWN) { 152 if (idx == -1) 153 idx = -1 - options_get_number(s->options, "base-index"); 154 if ((sc->wl = winlink_add(&s->windows, idx)) == NULL) { 155 xasprintf(cause, "couldn't add window %d", idx); 156 return (NULL); 157 } 158 default_window_size(sc->c, s, NULL, &sx, &sy, -1); 159 if ((w = window_create(sx, sy)) == 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->c; 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 if (sc->name != NULL) { 184 w->name = xstrdup(sc->name); 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 client *c = item->client; 207 struct session *s = sc->s; 208 struct window *w = sc->wl->window; 209 struct window_pane *new_wp; 210 struct environ *child; 211 struct environ_entry *ee; 212 char **argv, *cp, **argvp, *argv0, *cwd; 213 const char *cmd, *tmp; 214 int argc; 215 u_int idx; 216 struct termios now; 217 u_int hlimit; 218 struct winsize ws; 219 sigset_t set, oldset; 220 221 spawn_log(__func__, sc); 222 223 /* 224 * If we are respawning then get rid of the old process. Otherwise 225 * either create a new cell or assign to the one we are given. 226 */ 227 hlimit = options_get_number(s->options, "history-limit"); 228 if (sc->flags & SPAWN_RESPAWN) { 229 if (sc->wp0->fd != -1 && (~sc->flags & SPAWN_KILL)) { 230 window_pane_index(sc->wp0, &idx); 231 xasprintf(cause, "pane %s:%d.%u still active", 232 s->name, sc->wl->idx, idx); 233 return (NULL); 234 } 235 if (sc->wp0->fd != -1) { 236 bufferevent_free(sc->wp0->event); 237 close(sc->wp0->fd); 238 } 239 window_pane_reset_mode_all(sc->wp0); 240 screen_reinit(&sc->wp0->base); 241 input_init(sc->wp0); 242 new_wp = sc->wp0; 243 new_wp->flags &= ~(PANE_STATUSREADY|PANE_STATUSDRAWN); 244 } else if (sc->lc == NULL) { 245 new_wp = window_add_pane(w, NULL, hlimit, sc->flags); 246 layout_init(w, new_wp); 247 } else { 248 new_wp = window_add_pane(w, sc->wp0, hlimit, sc->flags); 249 layout_assign_pane(sc->lc, new_wp); 250 } 251 252 /* 253 * Now we have a pane with nothing running in it ready for the new 254 * process. Work out the command and arguments. 255 */ 256 if (sc->argc == 0 && (~sc->flags & SPAWN_RESPAWN)) { 257 cmd = options_get_string(s->options, "default-command"); 258 if (cmd != NULL && *cmd != '\0') { 259 argc = 1; 260 argv = (char **)&cmd; 261 } else { 262 argc = 0; 263 argv = NULL; 264 } 265 } else { 266 argc = sc->argc; 267 argv = sc->argv; 268 } 269 270 /* 271 * Replace the stored arguments if there are new ones. If not, the 272 * existing ones will be used (they will only exist for respawn). 273 */ 274 if (argc > 0) { 275 cmd_free_argv(new_wp->argc, new_wp->argv); 276 new_wp->argc = argc; 277 new_wp->argv = cmd_copy_argv(argc, argv); 278 } 279 280 /* 281 * Work out the current working directory. If respawning, use 282 * the pane's stored one unless specified. 283 */ 284 if (sc->cwd != NULL) 285 cwd = format_single(item, sc->cwd, c, s, NULL, NULL); 286 else if (~sc->flags & SPAWN_RESPAWN) 287 cwd = xstrdup(server_client_get_cwd(c, s)); 288 else 289 cwd = NULL; 290 if (cwd != NULL) { 291 free(new_wp->cwd); 292 new_wp->cwd = cwd; 293 } 294 295 /* Create an environment for this pane. */ 296 child = environ_for_session(s, 0); 297 if (sc->environ != NULL) 298 environ_copy(sc->environ, child); 299 environ_set(child, "TMUX_PANE", "%%%u", new_wp->id); 300 301 /* 302 * Then the PATH environment variable. The session one is replaced from 303 * the client if there is one because otherwise running "tmux new 304 * myprogram" wouldn't work if myprogram isn't in the session's path. 305 */ 306 if (c != NULL && c->session == NULL) { /* only unattached clients */ 307 ee = environ_find(c->environ, "PATH"); 308 if (ee != NULL) 309 environ_set(child, "PATH", "%s", ee->value); 310 } 311 if (environ_find(child, "PATH") == NULL) 312 environ_set(child, "%s", _PATH_DEFPATH); 313 314 /* Then the shell. If respawning, use the old one. */ 315 if (~sc->flags & SPAWN_RESPAWN) { 316 tmp = options_get_string(s->options, "default-shell"); 317 if (*tmp == '\0' || areshell(tmp)) 318 tmp = _PATH_BSHELL; 319 free(new_wp->shell); 320 new_wp->shell = xstrdup(tmp); 321 } 322 environ_set(child, "SHELL", "%s", new_wp->shell); 323 324 /* Log the arguments we are going to use. */ 325 log_debug("%s: shell=%s", __func__, new_wp->shell); 326 if (new_wp->argc != 0) { 327 cp = cmd_stringify_argv(new_wp->argc, new_wp->argv); 328 log_debug("%s: cmd=%s", __func__, cp); 329 free(cp); 330 } 331 if (cwd != NULL) 332 log_debug("%s: cwd=%s", __func__, cwd); 333 cmd_log_argv(new_wp->argc, new_wp->argv, "%s", __func__); 334 environ_log(child, "%s: environment ", __func__); 335 336 /* Initialize the window size. */ 337 memset(&ws, 0, sizeof ws); 338 ws.ws_col = screen_size_x(&new_wp->base); 339 ws.ws_row = screen_size_y(&new_wp->base); 340 341 /* Block signals until fork has completed. */ 342 sigfillset(&set); 343 sigprocmask(SIG_BLOCK, &set, &oldset); 344 345 /* If the command is empty, don't fork a child process. */ 346 if (sc->flags & SPAWN_EMPTY) { 347 new_wp->flags |= PANE_EMPTY; 348 new_wp->base.mode &= ~MODE_CURSOR; 349 new_wp->base.mode |= MODE_CRLF; 350 goto complete; 351 } 352 353 /* Fork the new process. */ 354 new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws); 355 if (new_wp->pid == -1) { 356 xasprintf(cause, "fork failed: %s", strerror(errno)); 357 new_wp->fd = -1; 358 if (~sc->flags & SPAWN_RESPAWN) { 359 layout_close_pane(new_wp); 360 window_remove_pane(w, new_wp); 361 } 362 sigprocmask(SIG_SETMASK, &oldset, NULL); 363 return (NULL); 364 } 365 366 /* In the parent process, everything is done now. */ 367 if (new_wp->pid != 0) 368 goto complete; 369 370 /* 371 * Child process. Change to the working directory or home if that 372 * fails. 373 */ 374 if (chdir(new_wp->cwd) != 0) { 375 if ((tmp = find_home()) == NULL || chdir(tmp) != 0) 376 chdir("/"); 377 } 378 379 /* 380 * Update terminal escape characters from the session if available and 381 * force VERASE to tmux's \177. 382 */ 383 if (tcgetattr(STDIN_FILENO, &now) != 0) 384 _exit(1); 385 if (s->tio != NULL) 386 memcpy(now.c_cc, s->tio->c_cc, sizeof now.c_cc); 387 now.c_cc[VERASE] = '\177'; 388 if (tcsetattr(STDIN_FILENO, TCSANOW, &now) != 0) 389 _exit(1); 390 391 /* Clean up file descriptors and signals and update the environment. */ 392 closefrom(STDERR_FILENO + 1); 393 proc_clear_signals(server_proc, 1); 394 sigprocmask(SIG_SETMASK, &oldset, NULL); 395 log_close(); 396 environ_push(child); 397 398 /* 399 * If given multiple arguments, use execvp(). Copy the arguments to 400 * ensure they end in a NULL. 401 */ 402 if (new_wp->argc != 0 && new_wp->argc != 1) { 403 argvp = cmd_copy_argv(new_wp->argc, new_wp->argv); 404 execvp(argvp[0], argvp); 405 _exit(1); 406 } 407 408 /* 409 * If one argument, pass it to $SHELL -c. Otherwise create a login 410 * shell. 411 */ 412 cp = strrchr(new_wp->shell, '/'); 413 if (new_wp->argc == 1) { 414 tmp = new_wp->argv[0]; 415 if (cp != NULL && cp[1] != '\0') 416 xasprintf(&argv0, "%s", cp + 1); 417 else 418 xasprintf(&argv0, "%s", new_wp->shell); 419 execl(new_wp->shell, argv0, "-c", tmp, (char *)NULL); 420 _exit(1); 421 } 422 if (cp != NULL && cp[1] != '\0') 423 xasprintf(&argv0, "-%s", cp + 1); 424 else 425 xasprintf(&argv0, "-%s", new_wp->shell); 426 execl(new_wp->shell, argv0, (char *)NULL); 427 _exit(1); 428 429 complete: 430 new_wp->pipe_off = 0; 431 new_wp->flags &= ~PANE_EXITED; 432 433 sigprocmask(SIG_SETMASK, &oldset, NULL); 434 window_pane_set_event(new_wp); 435 436 if (sc->flags & SPAWN_RESPAWN) 437 return (new_wp); 438 if ((~sc->flags & SPAWN_DETACHED) || w->active == NULL) { 439 if (sc->flags & SPAWN_NONOTIFY) 440 window_set_active_pane(w, new_wp, 0); 441 else 442 window_set_active_pane(w, new_wp, 1); 443 } 444 if (~sc->flags & SPAWN_NONOTIFY) 445 notify_window("window-layout-changed", w); 446 return (new_wp); 447 } 448