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 <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 }