src/shared/terminal-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <sys/ioctl.h>
  21 #include <sys/types.h>
  22 #include <sys/stat.h>
  23 #include <termios.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <signal.h>
  27 #include <time.h>
  28 #include <assert.h>
  29 #include <poll.h>
  30 #include <linux/vt.h>
  31 #include <linux/tiocl.h>
  32 #include <linux/kd.h>
  33
  34 #include "terminal-util.h"
  35 #include "time-util.h"
  36 #include "process-util.h"
  37 #include "util.h"
  38 #include "fileio.h"
  39 #include "path-util.h"
  40
  41 static volatile unsigned cached_columns = 0;
  42 static volatile unsigned cached_lines = 0;
  43
  44 int chvt(int vt) {
  45         _cleanup_close_ int fd;
  46
  47         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC);
  48         if (fd < 0)
  49                 return -errno;
  50
  51         if (vt < 0) {
  52                 int tiocl[2] = {
  53                         TIOCL_GETKMSGREDIRECT,
  54                         0
  55                 };
  56
  57                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  58                         return -errno;
  59
  60                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  61         }
  62
  63         if (ioctl(fd, VT_ACTIVATE, vt) < 0)
  64                 return -errno;
  65
  66         return 0;
  67 }
  68
  69 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  70         struct termios old_termios, new_termios;
  71         char c, line[LINE_MAX];
  72
  73         assert(f);
  74         assert(ret);
  75
  76         if (tcgetattr(fileno(f), &old_termios) >= 0) {
  77                 new_termios = old_termios;
  78
  79                 new_termios.c_lflag &= ~ICANON;
  80                 new_termios.c_cc[VMIN] = 1;
  81                 new_termios.c_cc[VTIME] = 0;
  82
  83                 if (tcsetattr(fileno(f), TCSADRAIN, &new_termios) >= 0) {
  84                         size_t k;
  85
  86                         if (t != USEC_INFINITY) {
  87                                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0) {
  88                                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
  89                                         return -ETIMEDOUT;
  90                                 }
  91                         }
  92
  93                         k = fread(&c, 1, 1, f);
  94
  95                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
  96
  97                         if (k <= 0)
  98                                 return -EIO;
  99
 100                         if (need_nl)
 101                                 *need_nl = c != '\n';
 102
 103                         *ret = c;
 104                         return 0;
 105                 }
 106         }
 107
 108         if (t != USEC_INFINITY) {
 109                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
 110                         return -ETIMEDOUT;
 111         }
 112
 113         errno = 0;
 114         if (!fgets(line, sizeof(line), f))
 115                 return errno ? -errno : -EIO;
 116
 117         truncate_nl(line);
 118
 119         if (strlen(line) != 1)
 120                 return -EBADMSG;
 121
 122         if (need_nl)
 123                 *need_nl = false;
 124
 125         *ret = line[0];
 126         return 0;
 127 }
 128
 129 int ask_char(char *ret, const char *replies, const char *text, ...) {
 130         int r;
 131
 132         assert(ret);
 133         assert(replies);
 134         assert(text);
 135
 136         for (;;) {
 137                 va_list ap;
 138                 char c;
 139                 bool need_nl = true;
 140
 141                 if (on_tty())
 142                         fputs(ANSI_HIGHLIGHT_ON, stdout);
 143
 144                 va_start(ap, text);
 145                 vprintf(text, ap);
 146                 va_end(ap);
 147
 148                 if (on_tty())
 149                         fputs(ANSI_HIGHLIGHT_OFF, stdout);
 150
 151                 fflush(stdout);
 152
 153                 r = read_one_char(stdin, &c, USEC_INFINITY, &need_nl);
 154                 if (r < 0) {
 155
 156                         if (r == -EBADMSG) {
 157                                 puts("Bad input, please try again.");
 158                                 continue;
 159                         }
 160
 161                         putchar('\n');
 162                         return r;
 163                 }
 164
 165                 if (need_nl)
 166                         putchar('\n');
 167
 168                 if (strchr(replies, c)) {
 169                         *ret = c;
 170                         return 0;
 171                 }
 172
 173                 puts("Read unexpected character, please try again.");
 174         }
 175 }
 176
 177 int ask_string(char **ret, const char *text, ...) {
 178         assert(ret);
 179         assert(text);
 180
 181         for (;;) {
 182                 char line[LINE_MAX];
 183                 va_list ap;
 184
 185                 if (on_tty())
 186                         fputs(ANSI_HIGHLIGHT_ON, stdout);
 187
 188                 va_start(ap, text);
 189                 vprintf(text, ap);
 190                 va_end(ap);
 191
 192                 if (on_tty())
 193                         fputs(ANSI_HIGHLIGHT_OFF, stdout);
 194
 195                 fflush(stdout);
 196
 197                 errno = 0;
 198                 if (!fgets(line, sizeof(line), stdin))
 199                         return errno ? -errno : -EIO;
 200
 201                 if (!endswith(line, "\n"))
 202                         putchar('\n');
 203                 else {
 204                         char *s;
 205
 206                         if (isempty(line))
 207                                 continue;
 208
 209                         truncate_nl(line);
 210                         s = strdup(line);
 211                         if (!s)
 212                                 return -ENOMEM;
 213
 214                         *ret = s;
 215                         return 0;
 216                 }
 217         }
 218 }
 219
 220 int reset_terminal_fd(int fd, bool switch_to_text) {
 221         struct termios termios;
 222         int r = 0;
 223
 224         /* Set terminal to some sane defaults */
 225
 226         assert(fd >= 0);
 227
 228         /* We leave locked terminal attributes untouched, so that
 229          * Plymouth may set whatever it wants to set, and we don't
 230          * interfere with that. */
 231
 232         /* Disable exclusive mode, just in case */
 233         ioctl(fd, TIOCNXCL);
 234
 235         /* Switch to text mode */
 236         if (switch_to_text)
 237                 ioctl(fd, KDSETMODE, KD_TEXT);
 238
 239         /* Enable console unicode mode */
 240         ioctl(fd, KDSKBMODE, K_UNICODE);
 241
 242         if (tcgetattr(fd, &termios) < 0) {
 243                 r = -errno;
 244                 goto finish;
 245         }
 246
 247         /* We only reset the stuff that matters to the software. How
 248          * hardware is set up we don't touch assuming that somebody
 249          * else will do that for us */
 250
 251         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 252         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 253         termios.c_oflag |= ONLCR;
 254         termios.c_cflag |= CREAD;
 255         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 256
 257         termios.c_cc[VINTR]    =   03;  /* ^C */
 258         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 259         termios.c_cc[VERASE]   = 0177;
 260         termios.c_cc[VKILL]    =  025;  /* ^X */
 261         termios.c_cc[VEOF]     =   04;  /* ^D */
 262         termios.c_cc[VSTART]   =  021;  /* ^Q */
 263         termios.c_cc[VSTOP]    =  023;  /* ^S */
 264         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 265         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 266         termios.c_cc[VWERASE]  =  027;  /* ^W */
 267         termios.c_cc[VREPRINT] =  022;  /* ^R */
 268         termios.c_cc[VEOL]     =    0;
 269         termios.c_cc[VEOL2]    =    0;
 270
 271         termios.c_cc[VTIME]  = 0;
 272         termios.c_cc[VMIN]   = 1;
 273
 274         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 275                 r = -errno;
 276
 277 finish:
 278         /* Just in case, flush all crap out */
 279         tcflush(fd, TCIOFLUSH);
 280
 281         return r;
 282 }
 283
 284 int reset_terminal(const char *name) {
 285         _cleanup_close_ int fd = -1;
 286
 287         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 288         if (fd < 0)
 289                 return fd;
 290
 291         return reset_terminal_fd(fd, true);
 292 }
 293
 294 int open_terminal(const char *name, int mode) {
 295         int fd, r;
 296         unsigned c = 0;
 297
 298         /*
 299          * If a TTY is in the process of being closed opening it might
 300          * cause EIO. This is horribly awful, but unlikely to be
 301          * changed in the kernel. Hence we work around this problem by
 302          * retrying a couple of times.
 303          *
 304          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 305          */
 306
 307         assert(!(mode & O_CREAT));
 308
 309         for (;;) {
 310                 fd = open(name, mode, 0);
 311                 if (fd >= 0)
 312                         break;
 313
 314                 if (errno != EIO)
 315                         return -errno;
 316
 317                 /* Max 1s in total */
 318                 if (c >= 20)
 319                         return -errno;
 320
 321                 usleep(50 * USEC_PER_MSEC);
 322                 c++;
 323         }
 324
 325         r = isatty(fd);
 326         if (r < 0) {
 327                 safe_close(fd);
 328                 return -errno;
 329         }
 330
 331         if (!r) {
 332                 safe_close(fd);
 333                 return -ENOTTY;
 334         }
 335
 336         return fd;
 337 }
 338
 339 int acquire_terminal(
 340                 const char *name,
 341                 bool fail,
 342                 bool force,
 343                 bool ignore_tiocstty_eperm,
 344                 usec_t timeout) {
 345
 346         int fd = -1, notify = -1, r = 0, wd = -1;
 347         usec_t ts = 0;
 348
 349         assert(name);
 350
 351         /* We use inotify to be notified when the tty is closed. We
 352          * create the watch before checking if we can actually acquire
 353          * it, so that we don't lose any event.
 354          *
 355          * Note: strictly speaking this actually watches for the
 356          * device being closed, it does *not* really watch whether a
 357          * tty loses its controlling process. However, unless some
 358          * rogue process uses TIOCNOTTY on /dev/tty *after* closing
 359          * its tty otherwise this will not become a problem. As long
 360          * as the administrator makes sure not configure any service
 361          * on the same tty as an untrusted user this should not be a
 362          * problem. (Which he probably should not do anyway.) */
 363
 364         if (timeout != USEC_INFINITY)
 365                 ts = now(CLOCK_MONOTONIC);
 366
 367         if (!fail && !force) {
 368                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 369                 if (notify < 0) {
 370                         r = -errno;
 371                         goto fail;
 372                 }
 373
 374                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 375                 if (wd < 0) {
 376                         r = -errno;
 377                         goto fail;
 378                 }
 379         }
 380
 381         for (;;) {
 382                 struct sigaction sa_old, sa_new = {
 383                         .sa_handler = SIG_IGN,
 384                         .sa_flags = SA_RESTART,
 385                 };
 386
 387                 if (notify >= 0) {
 388                         r = flush_fd(notify);
 389                         if (r < 0)
 390                                 goto fail;
 391                 }
 392
 393                 /* We pass here O_NOCTTY only so that we can check the return
 394                  * value TIOCSCTTY and have a reliable way to figure out if we
 395                  * successfully became the controlling process of the tty */
 396                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 397                 if (fd < 0)
 398                         return fd;
 399
 400                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 401                  * if we already own the tty. */
 402                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 403
 404                 /* First, try to get the tty */
 405                 if (ioctl(fd, TIOCSCTTY, force) < 0)
 406                         r = -errno;
 407
 408                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 409
 410                 /* Sometimes it makes sense to ignore TIOCSCTTY
 411                  * returning EPERM, i.e. when very likely we already
 412                  * are have this controlling terminal. */
 413                 if (r < 0 && r == -EPERM && ignore_tiocstty_eperm)
 414                         r = 0;
 415
 416                 if (r < 0 && (force || fail || r != -EPERM)) {
 417                         goto fail;
 418                 }
 419
 420                 if (r >= 0)
 421                         break;
 422
 423                 assert(!fail);
 424                 assert(!force);
 425                 assert(notify >= 0);
 426
 427                 for (;;) {
 428                         union inotify_event_buffer buffer;
 429                         struct inotify_event *e;
 430                         ssize_t l;
 431
 432                         if (timeout != USEC_INFINITY) {
 433                                 usec_t n;
 434
 435                                 n = now(CLOCK_MONOTONIC);
 436                                 if (ts + timeout < n) {
 437                                         r = -ETIMEDOUT;
 438                                         goto fail;
 439                                 }
 440
 441                                 r = fd_wait_for_event(fd, POLLIN, ts + timeout - n);
 442                                 if (r < 0)
 443                                         goto fail;
 444
 445                                 if (r == 0) {
 446                                         r = -ETIMEDOUT;
 447                                         goto fail;
 448                                 }
 449                         }
 450
 451                         l = read(notify, &buffer, sizeof(buffer));
 452                         if (l < 0) {
 453                                 if (errno == EINTR || errno == EAGAIN)
 454                                         continue;
 455
 456                                 r = -errno;
 457                                 goto fail;
 458                         }
 459
 460                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 461                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) {
 462                                         r = -EIO;
 463                                         goto fail;
 464                                 }
 465                         }
 466
 467                         break;
 468                 }
 469
 470                 /* We close the tty fd here since if the old session
 471                  * ended our handle will be dead. It's important that
 472                  * we do this after sleeping, so that we don't enter
 473                  * an endless loop. */
 474                 fd = safe_close(fd);
 475         }
 476
 477         safe_close(notify);
 478
 479         r = reset_terminal_fd(fd, true);
 480         if (r < 0)
 481                 log_warning_errno(r, "Failed to reset terminal: %m");
 482
 483         return fd;
 484
 485 fail:
 486         safe_close(fd);
 487         safe_close(notify);
 488
 489         return r;
 490 }
 491
 492 int release_terminal(void) {
 493         static const struct sigaction sa_new = {
 494                 .sa_handler = SIG_IGN,
 495                 .sa_flags = SA_RESTART,
 496         };
 497
 498         _cleanup_close_ int fd = -1;
 499         struct sigaction sa_old;
 500         int r = 0;
 501
 502         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_NDELAY|O_CLOEXEC);
 503         if (fd < 0)
 504                 return -errno;
 505
 506         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 507          * by our own TIOCNOTTY */
 508         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 509
 510         if (ioctl(fd, TIOCNOTTY) < 0)
 511                 r = -errno;
 512
 513         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 514
 515         return r;
 516 }
 517
 518 int terminal_vhangup_fd(int fd) {
 519         assert(fd >= 0);
 520
 521         if (ioctl(fd, TIOCVHANGUP) < 0)
 522                 return -errno;
 523
 524         return 0;
 525 }
 526
 527 int terminal_vhangup(const char *name) {
 528         _cleanup_close_ int fd;
 529
 530         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 531         if (fd < 0)
 532                 return fd;
 533
 534         return terminal_vhangup_fd(fd);
 535 }
 536
 537 int vt_disallocate(const char *name) {
 538         int fd, r;
 539         unsigned u;
 540
 541         /* Deallocate the VT if possible. If not possible
 542          * (i.e. because it is the active one), at least clear it
 543          * entirely (including the scrollback buffer) */
 544
 545         if (!startswith(name, "/dev/"))
 546                 return -EINVAL;
 547
 548         if (!tty_is_vc(name)) {
 549                 /* So this is not a VT. I guess we cannot deallocate
 550                  * it then. But let's at least clear the screen */
 551
 552                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 553                 if (fd < 0)
 554                         return fd;
 555
 556                 loop_write(fd,
 557                            "\033[r"    /* clear scrolling region */
 558                            "\033[H"    /* move home */
 559                            "\033[2J",  /* clear screen */
 560                            10, false);
 561                 safe_close(fd);
 562
 563                 return 0;
 564         }
 565
 566         if (!startswith(name, "/dev/tty"))
 567                 return -EINVAL;
 568
 569         r = safe_atou(name+8, &u);
 570         if (r < 0)
 571                 return r;
 572
 573         if (u <= 0)
 574                 return -EINVAL;
 575
 576         /* Try to deallocate */
 577         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC);
 578         if (fd < 0)
 579                 return fd;
 580
 581         r = ioctl(fd, VT_DISALLOCATE, u);
 582         safe_close(fd);
 583
 584         if (r >= 0)
 585                 return 0;
 586
 587         if (errno != EBUSY)
 588                 return -errno;
 589
 590         /* Couldn't deallocate, so let's clear it fully with
 591          * scrollback */
 592         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 593         if (fd < 0)
 594                 return fd;
 595
 596         loop_write(fd,
 597                    "\033[r"   /* clear scrolling region */
 598                    "\033[H"   /* move home */
 599                    "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 600                    10, false);
 601         safe_close(fd);
 602
 603         return 0;
 604 }
 605
 606 void warn_melody(void) {
 607         _cleanup_close_ int fd = -1;
 608
 609         fd = open("/dev/console", O_WRONLY|O_CLOEXEC|O_NOCTTY);
 610         if (fd < 0)
 611                 return;
 612
 613         /* Yeah, this is synchronous. Kinda sucks. But well... */
 614
 615         ioctl(fd, KIOCSOUND, (int)(1193180/440));
 616         usleep(125*USEC_PER_MSEC);
 617
 618         ioctl(fd, KIOCSOUND, (int)(1193180/220));
 619         usleep(125*USEC_PER_MSEC);
 620
 621         ioctl(fd, KIOCSOUND, (int)(1193180/220));
 622         usleep(125*USEC_PER_MSEC);
 623
 624         ioctl(fd, KIOCSOUND, 0);
 625 }
 626
 627 int make_console_stdio(void) {
 628         int fd, r;
 629
 630         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 631
 632         fd = acquire_terminal("/dev/console", false, true, true, USEC_INFINITY);
 633         if (fd < 0)
 634                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 635
 636         r = make_stdio(fd);
 637         if (r < 0)
 638                 return log_error_errno(r, "Failed to duplicate terminal fd: %m");
 639
 640         return 0;
 641 }
 642
 643 int status_vprintf(const char *status, bool ellipse, bool ephemeral, const char *format, va_list ap) {
 644         static const char status_indent[] = "         "; /* "[" STATUS "] " */
 645         _cleanup_free_ char *s = NULL;
 646         _cleanup_close_ int fd = -1;
 647         struct iovec iovec[6] = {};
 648         int n = 0;
 649         static bool prev_ephemeral;
 650
 651         assert(format);
 652
 653         /* This is independent of logging, as status messages are
 654          * optional and go exclusively to the console. */
 655
 656         if (vasprintf(&s, format, ap) < 0)
 657                 return log_oom();
 658
 659         fd = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC);
 660         if (fd < 0)
 661                 return fd;
 662
 663         if (ellipse) {
 664                 char *e;
 665                 size_t emax, sl;
 666                 int c;
 667
 668                 c = fd_columns(fd);
 669                 if (c <= 0)
 670                         c = 80;
 671
 672                 sl = status ? sizeof(status_indent)-1 : 0;
 673
 674                 emax = c - sl - 1;
 675                 if (emax < 3)
 676                         emax = 3;
 677
 678                 e = ellipsize(s, emax, 50);
 679                 if (e) {
 680                         free(s);
 681                         s = e;
 682                 }
 683         }
 684
 685         if (prev_ephemeral)
 686                 IOVEC_SET_STRING(iovec[n++], "\r" ANSI_ERASE_TO_END_OF_LINE);
 687         prev_ephemeral = ephemeral;
 688
 689         if (status) {
 690                 if (!isempty(status)) {
 691                         IOVEC_SET_STRING(iovec[n++], "[");
 692                         IOVEC_SET_STRING(iovec[n++], status);
 693                         IOVEC_SET_STRING(iovec[n++], "] ");
 694                 } else
 695                         IOVEC_SET_STRING(iovec[n++], status_indent);
 696         }
 697
 698         IOVEC_SET_STRING(iovec[n++], s);
 699         if (!ephemeral)
 700                 IOVEC_SET_STRING(iovec[n++], "\n");
 701
 702         if (writev(fd, iovec, n) < 0)
 703                 return -errno;
 704
 705         return 0;
 706 }
 707
 708 int status_printf(const char *status, bool ellipse, bool ephemeral, const char *format, ...) {
 709         va_list ap;
 710         int r;
 711
 712         assert(format);
 713
 714         va_start(ap, format);
 715         r = status_vprintf(status, ellipse, ephemeral, format, ap);
 716         va_end(ap);
 717
 718         return r;
 719 }
 720
 721 bool tty_is_vc(const char *tty) {
 722         assert(tty);
 723
 724         return vtnr_from_tty(tty) >= 0;
 725 }
 726
 727 bool tty_is_console(const char *tty) {
 728         assert(tty);
 729
 730         if (startswith(tty, "/dev/"))
 731                 tty += 5;
 732
 733         return streq(tty, "console");
 734 }
 735
 736 int vtnr_from_tty(const char *tty) {
 737         int i, r;
 738
 739         assert(tty);
 740
 741         if (startswith(tty, "/dev/"))
 742                 tty += 5;
 743
 744         if (!startswith(tty, "tty") )
 745                 return -EINVAL;
 746
 747         if (tty[3] < '0' || tty[3] > '9')
 748                 return -EINVAL;
 749
 750         r = safe_atoi(tty+3, &i);
 751         if (r < 0)
 752                 return r;
 753
 754         if (i < 0 || i > 63)
 755                 return -EINVAL;
 756
 757         return i;
 758 }
 759
 760 char *resolve_dev_console(char **active) {
 761         char *tty;
 762
 763         /* Resolve where /dev/console is pointing to, if /sys is actually ours
 764          * (i.e. not read-only-mounted which is a sign for container setups) */
 765
 766         if (path_is_read_only_fs("/sys") > 0)
 767                 return NULL;
 768
 769         if (read_one_line_file("/sys/class/tty/console/active", active) < 0)
 770                 return NULL;
 771
 772         /* If multiple log outputs are configured the last one is what
 773          * /dev/console points to */
 774         tty = strrchr(*active, ' ');
 775         if (tty)
 776                 tty++;
 777         else
 778                 tty = *active;
 779
 780         if (streq(tty, "tty0")) {
 781                 char *tmp;
 782
 783                 /* Get the active VC (e.g. tty1) */
 784                 if (read_one_line_file("/sys/class/tty/tty0/active", &tmp) >= 0) {
 785                         free(*active);
 786                         tty = *active = tmp;
 787                 }
 788         }
 789
 790         return tty;
 791 }
 792
 793 bool tty_is_vc_resolve(const char *tty) {
 794         _cleanup_free_ char *active = NULL;
 795
 796         assert(tty);
 797
 798         if (startswith(tty, "/dev/"))
 799                 tty += 5;
 800
 801         if (streq(tty, "console")) {
 802                 tty = resolve_dev_console(&active);
 803                 if (!tty)
 804                         return false;
 805         }
 806
 807         return tty_is_vc(tty);
 808 }
 809
 810 const char *default_term_for_tty(const char *tty) {
 811         assert(tty);
 812
 813         return tty_is_vc_resolve(tty) ? "TERM=linux" : "TERM=vt220";
 814 }
 815
 816 int fd_columns(int fd) {
 817         struct winsize ws = {};
 818
 819         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 820                 return -errno;
 821
 822         if (ws.ws_col <= 0)
 823                 return -EIO;
 824
 825         return ws.ws_col;
 826 }
 827
 828 unsigned columns(void) {
 829         const char *e;
 830         int c;
 831
 832         if (_likely_(cached_columns > 0))
 833                 return cached_columns;
 834
 835         c = 0;
 836         e = getenv("COLUMNS");
 837         if (e)
 838                 (void) safe_atoi(e, &c);
 839
 840         if (c <= 0)
 841                 c = fd_columns(STDOUT_FILENO);
 842
 843         if (c <= 0)
 844                 c = 80;
 845
 846         cached_columns = c;
 847         return cached_columns;
 848 }
 849
 850 int fd_lines(int fd) {
 851         struct winsize ws = {};
 852
 853         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 854                 return -errno;
 855
 856         if (ws.ws_row <= 0)
 857                 return -EIO;
 858
 859         return ws.ws_row;
 860 }
 861
 862 unsigned lines(void) {
 863         const char *e;
 864         int l;
 865
 866         if (_likely_(cached_lines > 0))
 867                 return cached_lines;
 868
 869         l = 0;
 870         e = getenv("LINES");
 871         if (e)
 872                 (void) safe_atoi(e, &l);
 873
 874         if (l <= 0)
 875                 l = fd_lines(STDOUT_FILENO);
 876
 877         if (l <= 0)
 878                 l = 24;
 879
 880         cached_lines = l;
 881         return cached_lines;
 882 }
 883
 884 /* intended to be used as a SIGWINCH sighandler */
 885 void columns_lines_cache_reset(int signum) {
 886         cached_columns = 0;
 887         cached_lines = 0;
 888 }
 889
 890 bool on_tty(void) {
 891         static int cached_on_tty = -1;
 892
 893         if (_unlikely_(cached_on_tty < 0))
 894                 cached_on_tty = isatty(STDOUT_FILENO) > 0;
 895
 896         return cached_on_tty;
 897 }
 898
 899 int make_stdio(int fd) {
 900         int r, s, t;
 901
 902         assert(fd >= 0);
 903
 904         r = dup2(fd, STDIN_FILENO);
 905         s = dup2(fd, STDOUT_FILENO);
 906         t = dup2(fd, STDERR_FILENO);
 907
 908         if (fd >= 3)
 909                 safe_close(fd);
 910
 911         if (r < 0 || s < 0 || t < 0)
 912                 return -errno;
 913
 914         /* Explicitly unset O_CLOEXEC, since if fd was < 3, then
 915          * dup2() was a NOP and the bit hence possibly set. */
 916         fd_cloexec(STDIN_FILENO, false);
 917         fd_cloexec(STDOUT_FILENO, false);
 918         fd_cloexec(STDERR_FILENO, false);
 919
 920         return 0;
 921 }
 922
 923 int make_null_stdio(void) {
 924         int null_fd;
 925
 926         null_fd = open("/dev/null", O_RDWR|O_NOCTTY);
 927         if (null_fd < 0)
 928                 return -errno;
 929
 930         return make_stdio(null_fd);
 931 }
 932
 933 int getttyname_malloc(int fd, char **ret) {
 934         size_t l = 100;
 935         int r;
 936
 937         assert(fd >= 0);
 938         assert(ret);
 939
 940         for (;;) {
 941                 char path[l];
 942
 943                 r = ttyname_r(fd, path, sizeof(path));
 944                 if (r == 0) {
 945                         const char *p;
 946                         char *c;
 947
 948                         p = startswith(path, "/dev/");
 949                         c = strdup(p ?: path);
 950                         if (!c)
 951                                 return -ENOMEM;
 952
 953                         *ret = c;
 954                         return 0;
 955                 }
 956
 957                 if (r != ERANGE)
 958                         return -r;
 959
 960                 l *= 2;
 961         }
 962
 963         return 0;
 964 }
 965
 966 int getttyname_harder(int fd, char **r) {
 967         int k;
 968         char *s = NULL;
 969
 970         k = getttyname_malloc(fd, &s);
 971         if (k < 0)
 972                 return k;
 973
 974         if (streq(s, "tty")) {
 975                 free(s);
 976                 return get_ctty(0, NULL, r);
 977         }
 978
 979         *r = s;
 980         return 0;
 981 }
 982
 983 int get_ctty_devnr(pid_t pid, dev_t *d) {
 984         int r;
 985         _cleanup_free_ char *line = NULL;
 986         const char *p;
 987         unsigned long ttynr;
 988
 989         assert(pid >= 0);
 990
 991         p = procfs_file_alloca(pid, "stat");
 992         r = read_one_line_file(p, &line);
 993         if (r < 0)
 994                 return r;
 995
 996         p = strrchr(line, ')');
 997         if (!p)
 998                 return -EIO;
 999
1000         p++;
1001
1002         if (sscanf(p, " "
1003                    "%*c "  /* state */
1004                    "%*d "  /* ppid */
1005                    "%*d "  /* pgrp */
1006                    "%*d "  /* session */
1007                    "%lu ", /* ttynr */
1008                    &ttynr) != 1)
1009                 return -EIO;
1010
1011         if (major(ttynr) == 0 && minor(ttynr) == 0)
1012                 return -ENOENT;
1013
1014         if (d)
1015                 *d = (dev_t) ttynr;
1016
1017         return 0;
1018 }
1019
1020 int get_ctty(pid_t pid, dev_t *_devnr, char **r) {
1021         char fn[sizeof("/dev/char/")-1 + 2*DECIMAL_STR_MAX(unsigned) + 1 + 1], *b = NULL;
1022         _cleanup_free_ char *s = NULL;
1023         const char *p;
1024         dev_t devnr;
1025         int k;
1026
1027         assert(r);
1028
1029         k = get_ctty_devnr(pid, &devnr);
1030         if (k < 0)
1031                 return k;
1032
1033         sprintf(fn, "/dev/char/%u:%u", major(devnr), minor(devnr));
1034
1035         k = readlink_malloc(fn, &s);
1036         if (k < 0) {
1037
1038                 if (k != -ENOENT)
1039                         return k;
1040
1041                 /* This is an ugly hack */
1042                 if (major(devnr) == 136) {
1043                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
1044                                 return -ENOMEM;
1045                 } else {
1046                         /* Probably something like the ptys which have no
1047                          * symlink in /dev/char. Let's return something
1048                          * vaguely useful. */
1049
1050                         b = strdup(fn + 5);
1051                         if (!b)
1052                                 return -ENOMEM;
1053                 }
1054         } else {
1055                 if (startswith(s, "/dev/"))
1056                         p = s + 5;
1057                 else if (startswith(s, "../"))
1058                         p = s + 3;
1059                 else
1060                         p = s;
1061
1062                 b = strdup(p);
1063                 if (!b)
1064                         return -ENOMEM;
1065         }
1066
1067         *r = b;
1068         if (_devnr)
1069                 *_devnr = devnr;
1070
1071         return 0;
1072 }