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, *new_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                 if (*cwd != '/') {
 233                         xasprintf(&new_cwd, "%s/%s", server_client_get_cwd(c,
 234                             target->s), cwd);
 235                         free(cwd);
 236                         cwd = new_cwd;
 237                 }
 238         } else if (~sc->flags & SPAWN_RESPAWN)
 239                 cwd = xstrdup(server_client_get_cwd(c, target->s));
 240         else
 241                 cwd = NULL;
 242
 243         /*
 244          * If we are respawning then get rid of the old process. Otherwise
 245          * either create a new cell or assign to the one we are given.
 246          */
 247         hlimit = options_get_number(s->options, "history-limit");
 248         if (sc->flags & SPAWN_RESPAWN) {
 249                 if (sc->wp0->fd != -1 && (~sc->flags & SPAWN_KILL)) {
 250                         window_pane_index(sc->wp0, &idx);
 251                         xasprintf(cause, "pane %s:%d.%u still active",
 252                             s->name, sc->wl->idx, idx);
 253                         free(cwd);
 254                         return (NULL);
 255                 }
 256                 if (sc->wp0->fd != -1) {
 257                         bufferevent_free(sc->wp0->event);
 258                         close(sc->wp0->fd);
 259                 }
 260                 window_pane_reset_mode_all(sc->wp0);
 261                 screen_reinit(&sc->wp0->base);
 262                 input_free(sc->wp0->ictx);
 263                 sc->wp0->ictx = NULL;
 264                 new_wp = sc->wp0;
 265                 new_wp->flags &= ~(PANE_STATUSREADY|PANE_STATUSDRAWN);
 266         } else if (sc->lc == NULL) {
 267                 new_wp = window_add_pane(w, NULL, hlimit, sc->flags);
 268                 layout_init(w, new_wp);
 269         } else {
 270                 new_wp = window_add_pane(w, sc->wp0, hlimit, sc->flags);
 271                 if (sc->flags & SPAWN_ZOOM)
 272                         layout_assign_pane(sc->lc, new_wp, 1);
 273                 else
 274                         layout_assign_pane(sc->lc, new_wp, 0);
 275         }
 276
 277         /*
 278          * Now we have a pane with nothing running in it ready for the new
 279          * process. Work out the command and arguments and store the working
 280          * directory.
 281          */
 282         if (sc->argc == 0 && (~sc->flags & SPAWN_RESPAWN)) {
 283                 cmd = options_get_string(s->options, "default-command");
 284                 if (cmd != NULL && *cmd != '\0') {
 285                         argc = 1;
 286                         argv = (char **)&cmd;
 287                 } else {
 288                         argc = 0;
 289                         argv = NULL;
 290                 }
 291         } else {
 292                 argc = sc->argc;
 293                 argv = sc->argv;
 294         }
 295         if (cwd != NULL) {
 296                 free(new_wp->cwd);
 297                 new_wp->cwd = cwd;
 298         }
 299
 300         /*
 301          * Replace the stored arguments if there are new ones. If not, the
 302          * existing ones will be used (they will only exist for respawn).
 303          */
 304         if (argc > 0) {
 305                 cmd_free_argv(new_wp->argc, new_wp->argv);
 306                 new_wp->argc = argc;
 307                 new_wp->argv = cmd_copy_argv(argc, argv);
 308         }
 309
 310         /* Create an environment for this pane. */
 311         child = environ_for_session(s, 0);
 312         if (sc->environ != NULL)
 313                 environ_copy(sc->environ, child);
 314         environ_set(child, "TMUX_PANE", 0, "%%%u", new_wp->id);
 315
 316         /*
 317          * Then the PATH environment variable. The session one is replaced from
 318          * the client if there is one because otherwise running "tmux new
 319          * myprogram" wouldn't work if myprogram isn't in the session's path.
 320          */
 321         if (c != NULL && c->session == NULL) { /* only unattached clients */
 322                 ee = environ_find(c->environ, "PATH");
 323                 if (ee != NULL)
 324                         environ_set(child, "PATH", 0, "%s", ee->value);
 325         }
 326         if (environ_find(child, "PATH") == NULL)
 327                 environ_set(child, "PATH", 0, "%s", _PATH_DEFPATH);
 328
 329         /* Then the shell. If respawning, use the old one. */
 330         if (~sc->flags & SPAWN_RESPAWN) {
 331                 tmp = options_get_string(s->options, "default-shell");
 332                 if (!checkshell(tmp))
 333                         tmp = _PATH_BSHELL;
 334                 free(new_wp->shell);
 335                 new_wp->shell = xstrdup(tmp);
 336         }
 337         environ_set(child, "SHELL", 0, "%s", new_wp->shell);
 338
 339         /* Log the arguments we are going to use. */
 340         log_debug("%s: shell=%s", __func__, new_wp->shell);
 341         if (new_wp->argc != 0) {
 342                 cp = cmd_stringify_argv(new_wp->argc, new_wp->argv);
 343                 log_debug("%s: cmd=%s", __func__, cp);
 344                 free(cp);
 345         }
 346         log_debug("%s: cwd=%s", __func__, new_wp->cwd);
 347         cmd_log_argv(new_wp->argc, new_wp->argv, "%s", __func__);
 348         environ_log(child, "%s: environment ", __func__);
 349
 350         /* Initialize the window size. */
 351         memset(&ws, 0, sizeof ws);
 352         ws.ws_col = screen_size_x(&new_wp->base);
 353         ws.ws_row = screen_size_y(&new_wp->base);
 354         ws.ws_xpixel = w->xpixel * ws.ws_col;
 355         ws.ws_ypixel = w->ypixel * ws.ws_row;
 356
 357         /* Block signals until fork has completed. */
 358         sigfillset(&set);
 359         sigprocmask(SIG_BLOCK, &set, &oldset);
 360
 361         /* If the command is empty, don't fork a child process. */
 362         if (sc->flags & SPAWN_EMPTY) {
 363                 new_wp->flags |= PANE_EMPTY;
 364                 new_wp->base.mode &= ~MODE_CURSOR;
 365                 new_wp->base.mode |= MODE_CRLF;
 366                 goto complete;
 367         }
 368
 369         /* Fork the new process. */
 370         new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws);
 371         if (new_wp->pid == -1) {
 372                 xasprintf(cause, "fork failed: %s", strerror(errno));
 373                 new_wp->fd = -1;
 374                 if (~sc->flags & SPAWN_RESPAWN) {
 375                         server_client_remove_pane(new_wp);
 376                         layout_close_pane(new_wp);
 377                         window_remove_pane(w, new_wp);
 378                 }
 379                 sigprocmask(SIG_SETMASK, &oldset, NULL);
 380                 environ_free(child);
 381                 return (NULL);
 382         }
 383
 384         /* In the parent process, everything is done now. */
 385         if (new_wp->pid != 0)
 386                 goto complete;
 387
 388         /*
 389          * Child process. Change to the working directory or home if that
 390          * fails.
 391          */
 392         if (chdir(new_wp->cwd) == 0)
 393                 environ_set(child, "PWD", 0, "%s", new_wp->cwd);
 394         else if ((tmp = find_home()) != NULL && chdir(tmp) == 0)
 395                 environ_set(child, "PWD", 0, "%s", tmp);
 396         else if (chdir("/") == 0)
 397                 environ_set(child, "PWD", 0, "/");
 398         else
 399                 fatal("chdir failed");
 400
 401         /*
 402          * Update terminal escape characters from the session if available and
 403          * force VERASE to tmux's backspace.
 404          */
 405         if (tcgetattr(STDIN_FILENO, &now) != 0)
 406                 _exit(1);
 407         if (s->tio != NULL)
 408                 memcpy(now.c_cc, s->tio->c_cc, sizeof now.c_cc);
 409         key = options_get_number(global_options, "backspace");
 410         if (key >= 0x7f)
 411                 now.c_cc[VERASE] = '\177';
 412         else
 413                 now.c_cc[VERASE] = key;
 414         if (tcsetattr(STDIN_FILENO, TCSANOW, &now) != 0)
 415                 _exit(1);
 416
 417         /* Clean up file descriptors and signals and update the environment. */
 418         closefrom(STDERR_FILENO + 1);
 419         proc_clear_signals(server_proc, 1);
 420         sigprocmask(SIG_SETMASK, &oldset, NULL);
 421         log_close();
 422         environ_push(child);
 423
 424         /*
 425          * If given multiple arguments, use execvp(). Copy the arguments to
 426          * ensure they end in a NULL.
 427          */
 428         if (new_wp->argc != 0 && new_wp->argc != 1) {
 429                 argvp = cmd_copy_argv(new_wp->argc, new_wp->argv);
 430                 execvp(argvp[0], argvp);
 431                 _exit(1);
 432         }
 433
 434         /*
 435          * If one argument, pass it to $SHELL -c. Otherwise create a login
 436          * shell.
 437          */
 438         cp = strrchr(new_wp->shell, '/');
 439         if (new_wp->argc == 1) {
 440                 tmp = new_wp->argv[0];
 441                 if (cp != NULL && cp[1] != '\0')
 442                         xasprintf(&argv0, "%s", cp + 1);
 443                 else
 444                         xasprintf(&argv0, "%s", new_wp->shell);
 445                 execl(new_wp->shell, argv0, "-c", tmp, (char *)NULL);
 446                 _exit(1);
 447         }
 448         if (cp != NULL && cp[1] != '\0')
 449                 xasprintf(&argv0, "-%s", cp + 1);
 450         else
 451                 xasprintf(&argv0, "-%s", new_wp->shell);
 452         execl(new_wp->shell, argv0, (char *)NULL);
 453         _exit(1);
 454
 455 complete:
 456         new_wp->flags &= ~PANE_EXITED;
 457
 458         sigprocmask(SIG_SETMASK, &oldset, NULL);
 459         window_pane_set_event(new_wp);
 460
 461         environ_free(child);
 462
 463         if (sc->flags & SPAWN_RESPAWN)
 464                 return (new_wp);
 465         if ((~sc->flags & SPAWN_DETACHED) || w->active == NULL) {
 466                 if (sc->flags & SPAWN_NONOTIFY)
 467                         window_set_active_pane(w, new_wp, 0);
 468                 else
 469                         window_set_active_pane(w, new_wp, 1);
 470         }
 471         if (~sc->flags & SPAWN_NONOTIFY)
 472                 notify_window("window-layout-changed", w);
 473         return (new_wp);
 474 }