spawn.c

   1 /* $OpenBSD$ */
   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 <signal.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include "tmux.h"
  28
  29 /*
  30  * Set up the environment and create a new window and pane or a new pane.
  31  *
  32  * We need to set up the following items:
  33  *
  34  * - history limit, comes from the session;
  35  *
  36  * - base index, comes from the session;
  37  *
  38  * - current working directory, may be specified - if it isn't it comes from
  39  *   either the client or the session;
  40  *
  41  * - PATH variable, comes from the client if any, otherwise from the session
  42  *   environment;
  43  *
  44  * - shell, comes from default-shell;
  45  *
  46  * - termios, comes from the session;
  47  *
  48  * - remaining environment, comes from the session.
  49  */
  50
  51 static void
  52 spawn_log(const char *from, struct spawn_context *sc)
  53 {
  54         struct session          *s = sc->s;
  55         struct winlink          *wl = sc->wl;
  56         struct window_pane      *wp0 = sc->wp0;
  57         const char              *name = cmdq_get_name(sc->item);
  58         char                     tmp[128];
  59
  60         log_debug("%s: %s, flags=%#x", from, name, sc->flags);
  61
  62         if (wl != NULL && wp0 != NULL)
  63                 xsnprintf(tmp, sizeof tmp, "wl=%d wp0=%%%u", wl->idx, wp0->id);
  64         else if (wl != NULL)
  65                 xsnprintf(tmp, sizeof tmp, "wl=%d wp0=none", wl->idx);
  66         else if (wp0 != NULL)
  67                 xsnprintf(tmp, sizeof tmp, "wl=none wp0=%%%u", wp0->id);
  68         else
  69                 xsnprintf(tmp, sizeof tmp, "wl=none wp0=none");
  70         log_debug("%s: s=$%u %s idx=%d", from, s->id, tmp, sc->idx);
  71         log_debug("%s: name=%s", from, sc->name == NULL ? "none" : sc->name);
  72 }
  73
  74 struct winlink *
  75 spawn_window(struct spawn_context *sc, char **cause)
  76 {
  77         struct cmdq_item        *item = sc->item;
  78         struct client           *c = cmdq_get_client(item);
  79         struct session          *s = sc->s;
  80         struct window           *w;
  81         struct window_pane      *wp;
  82         struct winlink          *wl;
  83         int                      idx = sc->idx;
  84         u_int                    sx, sy, xpixel, ypixel;
  85
  86         spawn_log(__func__, sc);
  87
  88         /*
  89          * If the window already exists, we are respawning, so destroy all the
  90          * panes except one.
  91          */
  92         if (sc->flags & SPAWN_RESPAWN) {
  93                 w = sc->wl->window;
  94                 if (~sc->flags & SPAWN_KILL) {
  95                         TAILQ_FOREACH(wp, &w->panes, entry) {
  96                                 if (wp->fd != -1)
  97                                         break;
  98                         }
  99                         if (wp != NULL) {
 100                                 xasprintf(cause, "window %s:%d still active",
 101                                     s->name, sc->wl->idx);
 102                                 return (NULL);
 103                         }
 104                 }
 105
 106                 sc->wp0 = TAILQ_FIRST(&w->panes);
 107                 TAILQ_REMOVE(&w->panes, sc->wp0, entry);
 108
 109                 layout_free(w);
 110                 window_destroy_panes(w);
 111
 112                 TAILQ_INSERT_HEAD(&w->panes, sc->wp0, entry);
 113                 window_pane_resize(sc->wp0, w->sx, w->sy);
 114
 115                 layout_init(w, sc->wp0);
 116                 window_set_active_pane(w, sc->wp0, 0);
 117         }
 118
 119         /*
 120          * Otherwise we have no window so we will need to create one. First
 121          * check if the given index already exists and destroy it if so.
 122          */
 123         if ((~sc->flags & SPAWN_RESPAWN) && idx != -1) {
 124                 wl = winlink_find_by_index(&s->windows, idx);
 125                 if (wl != NULL && (~sc->flags & SPAWN_KILL)) {
 126                         xasprintf(cause, "index %d in use", idx);
 127                         return (NULL);
 128                 }
 129                 if (wl != NULL) {
 130                         /*
 131                          * Can't use session_detach as it will destroy session
 132                          * if this makes it empty.
 133                          */
 134                         wl->flags &= ~WINLINK_ALERTFLAGS;
 135                         notify_session_window("window-unlinked", s, wl->window);
 136                         winlink_stack_remove(&s->lastw, wl);
 137                         winlink_remove(&s->windows, wl);
 138
 139                         if (s->curw == wl) {
 140                                 s->curw = NULL;
 141                                 sc->flags &= ~SPAWN_DETACHED;
 142                         }
 143                 }
 144         }
 145
 146         /* Then create a window if needed. */
 147         if (~sc->flags & SPAWN_RESPAWN) {
 148                 if (idx == -1)
 149                         idx = -1 - options_get_number(s->options, "base-index");
 150                 if ((sc->wl = winlink_add(&s->windows, idx)) == NULL) {
 151                         xasprintf(cause, "couldn't add window %d", idx);
 152                         return (NULL);
 153                 }
 154                 default_window_size(sc->tc, s, NULL, &sx, &sy, &xpixel, &ypixel,
 155                     -1);
 156                 if ((w = window_create(sx, sy, xpixel, ypixel)) == NULL) {
 157                         winlink_remove(&s->windows, sc->wl);
 158                         xasprintf(cause, "couldn't create window %d", idx);
 159                         return (NULL);
 160                 }
 161                 if (s->curw == NULL)
 162                         s->curw = sc->wl;
 163                 sc->wl->session = s;
 164                 w->latest = sc->tc;
 165                 winlink_set_window(sc->wl, w);
 166         } else
 167                 w = NULL;
 168         sc->flags |= SPAWN_NONOTIFY;
 169
 170         /* Spawn the pane. */
 171         wp = spawn_pane(sc, cause);
 172         if (wp == NULL) {
 173                 if (~sc->flags & SPAWN_RESPAWN)
 174                         winlink_remove(&s->windows, sc->wl);
 175                 return (NULL);
 176         }
 177
 178         /* Set the name of the new window. */
 179         if (~sc->flags & SPAWN_RESPAWN) {
 180                 free(w->name);
 181                 if (sc->name != NULL) {
 182                         w->name = format_single(item, sc->name, c, s, NULL,
 183                             NULL);
 184                         options_set_number(w->options, "automatic-rename", 0);
 185                 } else
 186                         w->name = default_window_name(w);
 187         }
 188
 189         /* Switch to the new window if required. */
 190         if (~sc->flags & SPAWN_DETACHED)
 191                 session_select(s, sc->wl->idx);
 192
 193         /* Fire notification if new window. */
 194         if (~sc->flags & SPAWN_RESPAWN)
 195                 notify_session_window("window-linked", s, w);
 196
 197         session_group_synchronize_from(s);
 198         return (sc->wl);
 199 }
 200
 201 struct window_pane *
 202 spawn_pane(struct spawn_context *sc, char **cause)
 203 {
 204         struct cmdq_item         *item = sc->item;
 205         struct cmd_find_state    *target = cmdq_get_target(item);
 206         struct client            *c = cmdq_get_client(item);
 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         key_code                  key;
 221
 222         spawn_log(__func__, sc);
 223
 224         /*
 225          * Work out the current working directory. If respawning, use
 226          * the pane's stored one unless specified.
 227          */
 228         if (sc->cwd != NULL)
 229                 cwd = format_single(item, sc->cwd, c, target->s, NULL, NULL);
 230         else if (~sc->flags & SPAWN_RESPAWN)
 231                 cwd = xstrdup(server_client_get_cwd(c, target->s));
 232         else
 233                 cwd = NULL;
 234
 235         /*
 236          * If we are respawning then get rid of the old process. Otherwise
 237          * either create a new cell or assign to the one we are given.
 238          */
 239         hlimit = options_get_number(s->options, "history-limit");
 240         if (sc->flags & SPAWN_RESPAWN) {
 241                 if (sc->wp0->fd != -1 && (~sc->flags & SPAWN_KILL)) {
 242                         window_pane_index(sc->wp0, &idx);
 243                         xasprintf(cause, "pane %s:%d.%u still active",
 244                             s->name, sc->wl->idx, idx);
 245                         free(cwd);
 246                         return (NULL);
 247                 }
 248                 if (sc->wp0->fd != -1) {
 249                         bufferevent_free(sc->wp0->event);
 250                         close(sc->wp0->fd);
 251                 }
 252                 window_pane_reset_mode_all(sc->wp0);
 253                 screen_reinit(&sc->wp0->base);
 254                 input_free(sc->wp0->ictx);
 255                 sc->wp0->ictx = NULL;
 256                 new_wp = sc->wp0;
 257                 new_wp->flags &= ~(PANE_STATUSREADY|PANE_STATUSDRAWN);
 258         } else if (sc->lc == NULL) {
 259                 new_wp = window_add_pane(w, NULL, hlimit, sc->flags);
 260                 layout_init(w, new_wp);
 261         } else {
 262                 new_wp = window_add_pane(w, sc->wp0, hlimit, sc->flags);
 263                 if (sc->flags & SPAWN_ZOOM)
 264                         layout_assign_pane(sc->lc, new_wp, 1);
 265                 else
 266                         layout_assign_pane(sc->lc, new_wp, 0);
 267         }
 268
 269         /*
 270          * Now we have a pane with nothing running in it ready for the new
 271          * process. Work out the command and arguments and store the working
 272          * directory.
 273          */
 274         if (sc->argc == 0 && (~sc->flags & SPAWN_RESPAWN)) {
 275                 cmd = options_get_string(s->options, "default-command");
 276                 if (cmd != NULL && *cmd != '\0') {
 277                         argc = 1;
 278                         argv = (char **)&cmd;
 279                 } else {
 280                         argc = 0;
 281                         argv = NULL;
 282                 }
 283         } else {
 284                 argc = sc->argc;
 285                 argv = sc->argv;
 286         }
 287         if (cwd != NULL) {
 288                 free(new_wp->cwd);
 289                 new_wp->cwd = cwd;
 290         }
 291
 292         /*
 293          * Replace the stored arguments if there are new ones. If not, the
 294          * existing ones will be used (they will only exist for respawn).
 295          */
 296         if (argc > 0) {
 297                 cmd_free_argv(new_wp->argc, new_wp->argv);
 298                 new_wp->argc = argc;
 299                 new_wp->argv = cmd_copy_argv(argc, argv);
 300         }
 301
 302         /* Create an environment for this pane. */
 303         child = environ_for_session(s, 0);
 304         if (sc->environ != NULL)
 305                 environ_copy(sc->environ, child);
 306         environ_set(child, "TMUX_PANE", 0, "%%%u", new_wp->id);
 307
 308         /*
 309          * Then the PATH environment variable. The session one is replaced from
 310          * the client if there is one because otherwise running "tmux new
 311          * myprogram" wouldn't work if myprogram isn't in the session's path.
 312          */
 313         if (c != NULL && c->session == NULL) { /* only unattached clients */
 314                 ee = environ_find(c->environ, "PATH");
 315                 if (ee != NULL)
 316                         environ_set(child, "PATH", 0, "%s", ee->value);
 317         }
 318         if (environ_find(child, "PATH") == NULL)
 319                 environ_set(child, "PATH", 0, "%s", _PATH_DEFPATH);
 320
 321         /* Then the shell. If respawning, use the old one. */
 322         if (~sc->flags & SPAWN_RESPAWN) {
 323                 tmp = options_get_string(s->options, "default-shell");
 324                 if (!checkshell(tmp))
 325                         tmp = _PATH_BSHELL;
 326                 free(new_wp->shell);
 327                 new_wp->shell = xstrdup(tmp);
 328         }
 329         environ_set(child, "SHELL", 0, "%s", new_wp->shell);
 330
 331         /* Log the arguments we are going to use. */
 332         log_debug("%s: shell=%s", __func__, new_wp->shell);
 333         if (new_wp->argc != 0) {
 334                 cp = cmd_stringify_argv(new_wp->argc, new_wp->argv);
 335                 log_debug("%s: cmd=%s", __func__, cp);
 336                 free(cp);
 337         }
 338         if (cwd != NULL)
 339                 log_debug("%s: cwd=%s", __func__, cwd);
 340         cmd_log_argv(new_wp->argc, new_wp->argv, "%s", __func__);
 341         environ_log(child, "%s: environment ", __func__);
 342
 343         /* Initialize the window size. */
 344         memset(&ws, 0, sizeof ws);
 345         ws.ws_col = screen_size_x(&new_wp->base);
 346         ws.ws_row = screen_size_y(&new_wp->base);
 347         ws.ws_xpixel = w->xpixel * ws.ws_col;
 348         ws.ws_ypixel = w->ypixel * ws.ws_row;
 349
 350         /* Block signals until fork has completed. */
 351         sigfillset(&set);
 352         sigprocmask(SIG_BLOCK, &set, &oldset);
 353
 354         /* If the command is empty, don't fork a child process. */
 355         if (sc->flags & SPAWN_EMPTY) {
 356                 new_wp->flags |= PANE_EMPTY;
 357                 new_wp->base.mode &= ~MODE_CURSOR;
 358                 new_wp->base.mode |= MODE_CRLF;
 359                 goto complete;
 360         }
 361
 362         /* Fork the new process. */
 363         new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws);
 364         if (new_wp->pid == -1) {
 365                 xasprintf(cause, "fork failed: %s", strerror(errno));
 366                 new_wp->fd = -1;
 367                 if (~sc->flags & SPAWN_RESPAWN) {
 368                         server_client_remove_pane(new_wp);
 369                         layout_close_pane(new_wp);
 370                         window_remove_pane(w, new_wp);
 371                 }
 372                 sigprocmask(SIG_SETMASK, &oldset, NULL);
 373                 environ_free(child);
 374                 return (NULL);
 375         }
 376
 377         /* In the parent process, everything is done now. */
 378         if (new_wp->pid != 0)
 379                 goto complete;
 380
 381         /*
 382          * Child process. Change to the working directory or home if that
 383          * fails.
 384          */
 385         if (chdir(new_wp->cwd) != 0 &&
 386             ((tmp = find_home()) == NULL || chdir(tmp) != 0) &&
 387             chdir("/") != 0)
 388                 fatal("chdir failed");
 389
 390         /*
 391          * Update terminal escape characters from the session if available and
 392          * force VERASE to tmux's backspace.
 393          */
 394         if (tcgetattr(STDIN_FILENO, &now) != 0)
 395                 _exit(1);
 396         if (s->tio != NULL)
 397                 memcpy(now.c_cc, s->tio->c_cc, sizeof now.c_cc);
 398         key = options_get_number(global_options, "backspace");
 399         if (key >= 0x7f)
 400                 now.c_cc[VERASE] = '\177';
 401         else
 402                 now.c_cc[VERASE] = key;
 403 #ifdef IUTF8
 404         now.c_iflag |= IUTF8;
 405 #endif
 406         if (tcsetattr(STDIN_FILENO, TCSANOW, &now) != 0)
 407                 _exit(1);
 408
 409         /* Clean up file descriptors and signals and update the environment. */
 410         closefrom(STDERR_FILENO + 1);
 411         proc_clear_signals(server_proc, 1);
 412         sigprocmask(SIG_SETMASK, &oldset, NULL);
 413         log_close();
 414         environ_push(child);
 415
 416         /*
 417          * If given multiple arguments, use execvp(). Copy the arguments to
 418          * ensure they end in a NULL.
 419          */
 420         if (new_wp->argc != 0 && new_wp->argc != 1) {
 421                 argvp = cmd_copy_argv(new_wp->argc, new_wp->argv);
 422                 execvp(argvp[0], argvp);
 423                 _exit(1);
 424         }
 425
 426         /*
 427          * If one argument, pass it to $SHELL -c. Otherwise create a login
 428          * shell.
 429          */
 430         cp = strrchr(new_wp->shell, '/');
 431         if (new_wp->argc == 1) {
 432                 tmp = new_wp->argv[0];
 433                 if (cp != NULL && cp[1] != '\0')
 434                         xasprintf(&argv0, "%s", cp + 1);
 435                 else
 436                         xasprintf(&argv0, "%s", new_wp->shell);
 437                 execl(new_wp->shell, argv0, "-c", tmp, (char *)NULL);
 438                 _exit(1);
 439         }
 440         if (cp != NULL && cp[1] != '\0')
 441                 xasprintf(&argv0, "-%s", cp + 1);
 442         else
 443                 xasprintf(&argv0, "-%s", new_wp->shell);
 444         execl(new_wp->shell, argv0, (char *)NULL);
 445         _exit(1);
 446
 447 complete:
 448 #ifdef HAVE_UTEMPTER
 449         if (~new_wp->flags & PANE_EMPTY) {
 450                 xasprintf(&cp, "tmux(%lu).%%%u", (long)getpid(), new_wp->id);
 451                 utempter_add_record(new_wp->fd, cp);
 452                 kill(getpid(), SIGCHLD);
 453                 free(cp);
 454         }
 455 #endif
 456
 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 }