src/basic/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|O_NONBLOCK);
  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         /* We open the terminal with O_NONBLOCK here, to ensure we
 288          * don't block on carrier if this is a terminal with carrier
 289          * configured. */
 290
 291         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 292         if (fd < 0)
 293                 return fd;
 294
 295         return reset_terminal_fd(fd, true);
 296 }
 297
 298 int open_terminal(const char *name, int mode) {
 299         int fd, r;
 300         unsigned c = 0;
 301
 302         /*
 303          * If a TTY is in the process of being closed opening it might
 304          * cause EIO. This is horribly awful, but unlikely to be
 305          * changed in the kernel. Hence we work around this problem by
 306          * retrying a couple of times.
 307          *
 308          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 309          */
 310
 311         assert(!(mode & O_CREAT));
 312
 313         for (;;) {
 314                 fd = open(name, mode, 0);
 315                 if (fd >= 0)
 316                         break;
 317
 318                 if (errno != EIO)
 319                         return -errno;
 320
 321                 /* Max 1s in total */
 322                 if (c >= 20)
 323                         return -errno;
 324
 325                 usleep(50 * USEC_PER_MSEC);
 326                 c++;
 327         }
 328
 329         r = isatty(fd);
 330         if (r < 0) {
 331                 safe_close(fd);
 332                 return -errno;
 333         }
 334
 335         if (!r) {
 336                 safe_close(fd);
 337                 return -ENOTTY;
 338         }
 339
 340         return fd;
 341 }
 342
 343 int acquire_terminal(
 344                 const char *name,
 345                 bool fail,
 346                 bool force,
 347                 bool ignore_tiocstty_eperm,
 348                 usec_t timeout) {
 349
 350         int fd = -1, notify = -1, r = 0, wd = -1;
 351         usec_t ts = 0;
 352
 353         assert(name);
 354
 355         /* We use inotify to be notified when the tty is closed. We
 356          * create the watch before checking if we can actually acquire
 357          * it, so that we don't lose any event.
 358          *
 359          * Note: strictly speaking this actually watches for the
 360          * device being closed, it does *not* really watch whether a
 361          * tty loses its controlling process. However, unless some
 362          * rogue process uses TIOCNOTTY on /dev/tty *after* closing
 363          * its tty otherwise this will not become a problem. As long
 364          * as the administrator makes sure not configure any service
 365          * on the same tty as an untrusted user this should not be a
 366          * problem. (Which he probably should not do anyway.) */
 367
 368         if (timeout != USEC_INFINITY)
 369                 ts = now(CLOCK_MONOTONIC);
 370
 371         if (!fail && !force) {
 372                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 373                 if (notify < 0) {
 374                         r = -errno;
 375                         goto fail;
 376                 }
 377
 378                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 379                 if (wd < 0) {
 380                         r = -errno;
 381                         goto fail;
 382                 }
 383         }
 384
 385         for (;;) {
 386                 struct sigaction sa_old, sa_new = {
 387                         .sa_handler = SIG_IGN,
 388                         .sa_flags = SA_RESTART,
 389                 };
 390
 391                 if (notify >= 0) {
 392                         r = flush_fd(notify);
 393                         if (r < 0)
 394                                 goto fail;
 395                 }
 396
 397                 /* We pass here O_NOCTTY only so that we can check the return
 398                  * value TIOCSCTTY and have a reliable way to figure out if we
 399                  * successfully became the controlling process of the tty */
 400                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 401                 if (fd < 0)
 402                         return fd;
 403
 404                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 405                  * if we already own the tty. */
 406                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 407
 408                 /* First, try to get the tty */
 409                 if (ioctl(fd, TIOCSCTTY, force) < 0)
 410                         r = -errno;
 411
 412                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 413
 414                 /* Sometimes it makes sense to ignore TIOCSCTTY
 415                  * returning EPERM, i.e. when very likely we already
 416                  * are have this controlling terminal. */
 417                 if (r < 0 && r == -EPERM && ignore_tiocstty_eperm)
 418                         r = 0;
 419
 420                 if (r < 0 && (force || fail || r != -EPERM)) {
 421                         goto fail;
 422                 }
 423
 424                 if (r >= 0)
 425                         break;
 426
 427                 assert(!fail);
 428                 assert(!force);
 429                 assert(notify >= 0);
 430
 431                 for (;;) {
 432                         union inotify_event_buffer buffer;
 433                         struct inotify_event *e;
 434                         ssize_t l;
 435
 436                         if (timeout != USEC_INFINITY) {
 437                                 usec_t n;
 438
 439                                 n = now(CLOCK_MONOTONIC);
 440                                 if (ts + timeout < n) {
 441                                         r = -ETIMEDOUT;
 442                                         goto fail;
 443                                 }
 444
 445                                 r = fd_wait_for_event(fd, POLLIN, ts + timeout - n);
 446                                 if (r < 0)
 447                                         goto fail;
 448
 449                                 if (r == 0) {
 450                                         r = -ETIMEDOUT;
 451                                         goto fail;
 452                                 }
 453                         }
 454
 455                         l = read(notify, &buffer, sizeof(buffer));
 456                         if (l < 0) {
 457                                 if (errno == EINTR || errno == EAGAIN)
 458                                         continue;
 459
 460                                 r = -errno;
 461                                 goto fail;
 462                         }
 463
 464                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 465                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) {
 466                                         r = -EIO;
 467                                         goto fail;
 468                                 }
 469                         }
 470
 471                         break;
 472                 }
 473
 474                 /* We close the tty fd here since if the old session
 475                  * ended our handle will be dead. It's important that
 476                  * we do this after sleeping, so that we don't enter
 477                  * an endless loop. */
 478                 fd = safe_close(fd);
 479         }
 480
 481         safe_close(notify);
 482
 483         r = reset_terminal_fd(fd, true);
 484         if (r < 0)
 485                 log_warning_errno(r, "Failed to reset terminal: %m");
 486
 487         return fd;
 488
 489 fail:
 490         safe_close(fd);
 491         safe_close(notify);
 492
 493         return r;
 494 }
 495
 496 int release_terminal(void) {
 497         static const struct sigaction sa_new = {
 498                 .sa_handler = SIG_IGN,
 499                 .sa_flags = SA_RESTART,
 500         };
 501
 502         _cleanup_close_ int fd = -1;
 503         struct sigaction sa_old;
 504         int r = 0;
 505
 506         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 507         if (fd < 0)
 508                 return -errno;
 509
 510         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 511          * by our own TIOCNOTTY */
 512         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 513
 514         if (ioctl(fd, TIOCNOTTY) < 0)
 515                 r = -errno;
 516
 517         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 518
 519         return r;
 520 }
 521
 522 int terminal_vhangup_fd(int fd) {
 523         assert(fd >= 0);
 524
 525         if (ioctl(fd, TIOCVHANGUP) < 0)
 526                 return -errno;
 527
 528         return 0;
 529 }
 530
 531 int terminal_vhangup(const char *name) {
 532         _cleanup_close_ int fd;
 533
 534         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 535         if (fd < 0)
 536                 return fd;
 537
 538         return terminal_vhangup_fd(fd);
 539 }
 540
 541 int vt_disallocate(const char *name) {
 542         int fd, r;
 543         unsigned u;
 544
 545         /* Deallocate the VT if possible. If not possible
 546          * (i.e. because it is the active one), at least clear it
 547          * entirely (including the scrollback buffer) */
 548
 549         if (!startswith(name, "/dev/"))
 550                 return -EINVAL;
 551
 552         if (!tty_is_vc(name)) {
 553                 /* So this is not a VT. I guess we cannot deallocate
 554                  * it then. But let's at least clear the screen */
 555
 556                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 557                 if (fd < 0)
 558                         return fd;
 559
 560                 loop_write(fd,
 561                            "\033[r"    /* clear scrolling region */
 562                            "\033[H"    /* move home */
 563                            "\033[2J",  /* clear screen */
 564                            10, false);
 565                 safe_close(fd);
 566
 567                 return 0;
 568         }
 569
 570         if (!startswith(name, "/dev/tty"))
 571                 return -EINVAL;
 572
 573         r = safe_atou(name+8, &u);
 574         if (r < 0)
 575                 return r;
 576
 577         if (u <= 0)
 578                 return -EINVAL;
 579
 580         /* Try to deallocate */
 581         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 582         if (fd < 0)
 583                 return fd;
 584
 585         r = ioctl(fd, VT_DISALLOCATE, u);
 586         safe_close(fd);
 587
 588         if (r >= 0)
 589                 return 0;
 590
 591         if (errno != EBUSY)
 592                 return -errno;
 593
 594         /* Couldn't deallocate, so let's clear it fully with
 595          * scrollback */
 596         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 597         if (fd < 0)
 598                 return fd;
 599
 600         loop_write(fd,
 601                    "\033[r"   /* clear scrolling region */
 602                    "\033[H"   /* move home */
 603                    "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 604                    10, false);
 605         safe_close(fd);
 606
 607         return 0;
 608 }
 609
 610 void warn_melody(void) {
 611         _cleanup_close_ int fd = -1;
 612
 613         fd = open("/dev/console", O_WRONLY|O_CLOEXEC|O_NOCTTY);
 614         if (fd < 0)
 615                 return;
 616
 617         /* Yeah, this is synchronous. Kinda sucks. But well... */
 618
 619         ioctl(fd, KIOCSOUND, (int)(1193180/440));
 620         usleep(125*USEC_PER_MSEC);
 621
 622         ioctl(fd, KIOCSOUND, (int)(1193180/220));
 623         usleep(125*USEC_PER_MSEC);
 624
 625         ioctl(fd, KIOCSOUND, (int)(1193180/220));
 626         usleep(125*USEC_PER_MSEC);
 627
 628         ioctl(fd, KIOCSOUND, 0);
 629 }
 630
 631 int make_console_stdio(void) {
 632         int fd, r;
 633
 634         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 635
 636         fd = acquire_terminal("/dev/console", false, true, true, USEC_INFINITY);
 637         if (fd < 0)
 638                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 639
 640         r = make_stdio(fd);
 641         if (r < 0)
 642                 return log_error_errno(r, "Failed to duplicate terminal fd: %m");
 643
 644         return 0;
 645 }
 646
 647 int status_vprintf(const char *status, bool ellipse, bool ephemeral, const char *format, va_list ap) {
 648         static const char status_indent[] = "         "; /* "[" STATUS "] " */
 649         _cleanup_free_ char *s = NULL;
 650         _cleanup_close_ int fd = -1;
 651         struct iovec iovec[6] = {};
 652         int n = 0;
 653         static bool prev_ephemeral;
 654
 655         assert(format);
 656
 657         /* This is independent of logging, as status messages are
 658          * optional and go exclusively to the console. */
 659
 660         if (vasprintf(&s, format, ap) < 0)
 661                 return log_oom();
 662
 663         fd = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC);
 664         if (fd < 0)
 665                 return fd;
 666
 667         if (ellipse) {
 668                 char *e;
 669                 size_t emax, sl;
 670                 int c;
 671
 672                 c = fd_columns(fd);
 673                 if (c <= 0)
 674                         c = 80;
 675
 676                 sl = status ? sizeof(status_indent)-1 : 0;
 677
 678                 emax = c - sl - 1;
 679                 if (emax < 3)
 680                         emax = 3;
 681
 682                 e = ellipsize(s, emax, 50);
 683                 if (e) {
 684                         free(s);
 685                         s = e;
 686                 }
 687         }
 688
 689         if (prev_ephemeral)
 690                 IOVEC_SET_STRING(iovec[n++], "\r" ANSI_ERASE_TO_END_OF_LINE);
 691         prev_ephemeral = ephemeral;
 692
 693         if (status) {
 694                 if (!isempty(status)) {
 695                         IOVEC_SET_STRING(iovec[n++], "[");
 696                         IOVEC_SET_STRING(iovec[n++], status);
 697                         IOVEC_SET_STRING(iovec[n++], "] ");
 698                 } else
 699                         IOVEC_SET_STRING(iovec[n++], status_indent);
 700         }
 701
 702         IOVEC_SET_STRING(iovec[n++], s);
 703         if (!ephemeral)
 704                 IOVEC_SET_STRING(iovec[n++], "\n");
 705
 706         if (writev(fd, iovec, n) < 0)
 707                 return -errno;
 708
 709         return 0;
 710 }
 711
 712 int status_printf(const char *status, bool ellipse, bool ephemeral, const char *format, ...) {
 713         va_list ap;
 714         int r;
 715
 716         assert(format);
 717
 718         va_start(ap, format);
 719         r = status_vprintf(status, ellipse, ephemeral, format, ap);
 720         va_end(ap);
 721
 722         return r;
 723 }
 724
 725 bool tty_is_vc(const char *tty) {
 726         assert(tty);
 727
 728         return vtnr_from_tty(tty) >= 0;
 729 }
 730
 731 bool tty_is_console(const char *tty) {
 732         assert(tty);
 733
 734         if (startswith(tty, "/dev/"))
 735                 tty += 5;
 736
 737         return streq(tty, "console");
 738 }
 739
 740 int vtnr_from_tty(const char *tty) {
 741         int i, r;
 742
 743         assert(tty);
 744
 745         if (startswith(tty, "/dev/"))
 746                 tty += 5;
 747
 748         if (!startswith(tty, "tty") )
 749                 return -EINVAL;
 750
 751         if (tty[3] < '0' || tty[3] > '9')
 752                 return -EINVAL;
 753
 754         r = safe_atoi(tty+3, &i);
 755         if (r < 0)
 756                 return r;
 757
 758         if (i < 0 || i > 63)
 759                 return -EINVAL;
 760
 761         return i;
 762 }
 763
 764 char *resolve_dev_console(char **active) {
 765         char *tty;
 766
 767         /* Resolve where /dev/console is pointing to, if /sys is actually ours
 768          * (i.e. not read-only-mounted which is a sign for container setups) */
 769
 770         if (path_is_read_only_fs("/sys") > 0)
 771                 return NULL;
 772
 773         if (read_one_line_file("/sys/class/tty/console/active", active) < 0)
 774                 return NULL;
 775
 776         /* If multiple log outputs are configured the last one is what
 777          * /dev/console points to */
 778         tty = strrchr(*active, ' ');
 779         if (tty)
 780                 tty++;
 781         else
 782                 tty = *active;
 783
 784         if (streq(tty, "tty0")) {
 785                 char *tmp;
 786
 787                 /* Get the active VC (e.g. tty1) */
 788                 if (read_one_line_file("/sys/class/tty/tty0/active", &tmp) >= 0) {
 789                         free(*active);
 790                         tty = *active = tmp;
 791                 }
 792         }
 793
 794         return tty;
 795 }
 796
 797 bool tty_is_vc_resolve(const char *tty) {
 798         _cleanup_free_ char *active = NULL;
 799
 800         assert(tty);
 801
 802         if (startswith(tty, "/dev/"))
 803                 tty += 5;
 804
 805         if (streq(tty, "console")) {
 806                 tty = resolve_dev_console(&active);
 807                 if (!tty)
 808                         return false;
 809         }
 810
 811         return tty_is_vc(tty);
 812 }
 813
 814 const char *default_term_for_tty(const char *tty) {
 815         assert(tty);
 816
 817         return tty_is_vc_resolve(tty) ? "TERM=linux" : "TERM=vt220";
 818 }
 819
 820 int fd_columns(int fd) {
 821         struct winsize ws = {};
 822
 823         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 824                 return -errno;
 825
 826         if (ws.ws_col <= 0)
 827                 return -EIO;
 828
 829         return ws.ws_col;
 830 }
 831
 832 unsigned columns(void) {
 833         const char *e;
 834         int c;
 835
 836         if (_likely_(cached_columns > 0))
 837                 return cached_columns;
 838
 839         c = 0;
 840         e = getenv("COLUMNS");
 841         if (e)
 842                 (void) safe_atoi(e, &c);
 843
 844         if (c <= 0)
 845                 c = fd_columns(STDOUT_FILENO);
 846
 847         if (c <= 0)
 848                 c = 80;
 849
 850         cached_columns = c;
 851         return cached_columns;
 852 }
 853
 854 int fd_lines(int fd) {
 855         struct winsize ws = {};
 856
 857         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 858                 return -errno;
 859
 860         if (ws.ws_row <= 0)
 861                 return -EIO;
 862
 863         return ws.ws_row;
 864 }
 865
 866 unsigned lines(void) {
 867         const char *e;
 868         int l;
 869
 870         if (_likely_(cached_lines > 0))
 871                 return cached_lines;
 872
 873         l = 0;
 874         e = getenv("LINES");
 875         if (e)
 876                 (void) safe_atoi(e, &l);
 877
 878         if (l <= 0)
 879                 l = fd_lines(STDOUT_FILENO);
 880
 881         if (l <= 0)
 882                 l = 24;
 883
 884         cached_lines = l;
 885         return cached_lines;
 886 }
 887
 888 /* intended to be used as a SIGWINCH sighandler */
 889 void columns_lines_cache_reset(int signum) {
 890         cached_columns = 0;
 891         cached_lines = 0;
 892 }
 893
 894 bool on_tty(void) {
 895         static int cached_on_tty = -1;
 896
 897         if (_unlikely_(cached_on_tty < 0))
 898                 cached_on_tty = isatty(STDOUT_FILENO) > 0;
 899
 900         return cached_on_tty;
 901 }
 902
 903 int make_stdio(int fd) {
 904         int r, s, t;
 905
 906         assert(fd >= 0);
 907
 908         r = dup2(fd, STDIN_FILENO);
 909         s = dup2(fd, STDOUT_FILENO);
 910         t = dup2(fd, STDERR_FILENO);
 911
 912         if (fd >= 3)
 913                 safe_close(fd);
 914
 915         if (r < 0 || s < 0 || t < 0)
 916                 return -errno;
 917
 918         /* Explicitly unset O_CLOEXEC, since if fd was < 3, then
 919          * dup2() was a NOP and the bit hence possibly set. */
 920         fd_cloexec(STDIN_FILENO, false);
 921         fd_cloexec(STDOUT_FILENO, false);
 922         fd_cloexec(STDERR_FILENO, false);
 923
 924         return 0;
 925 }
 926
 927 int make_null_stdio(void) {
 928         int null_fd;
 929
 930         null_fd = open("/dev/null", O_RDWR|O_NOCTTY);
 931         if (null_fd < 0)
 932                 return -errno;
 933
 934         return make_stdio(null_fd);
 935 }
 936
 937 int getttyname_malloc(int fd, char **ret) {
 938         size_t l = 100;
 939         int r;
 940
 941         assert(fd >= 0);
 942         assert(ret);
 943
 944         for (;;) {
 945                 char path[l];
 946
 947                 r = ttyname_r(fd, path, sizeof(path));
 948                 if (r == 0) {
 949                         const char *p;
 950                         char *c;
 951
 952                         p = startswith(path, "/dev/");
 953                         c = strdup(p ?: path);
 954                         if (!c)
 955                                 return -ENOMEM;
 956
 957                         *ret = c;
 958                         return 0;
 959                 }
 960
 961                 if (r != ERANGE)
 962                         return -r;
 963
 964                 l *= 2;
 965         }
 966
 967         return 0;
 968 }
 969
 970 int getttyname_harder(int fd, char **r) {
 971         int k;
 972         char *s = NULL;
 973
 974         k = getttyname_malloc(fd, &s);
 975         if (k < 0)
 976                 return k;
 977
 978         if (streq(s, "tty")) {
 979                 free(s);
 980                 return get_ctty(0, NULL, r);
 981         }
 982
 983         *r = s;
 984         return 0;
 985 }
 986
 987 int get_ctty_devnr(pid_t pid, dev_t *d) {
 988         int r;
 989         _cleanup_free_ char *line = NULL;
 990         const char *p;
 991         unsigned long ttynr;
 992
 993         assert(pid >= 0);
 994
 995         p = procfs_file_alloca(pid, "stat");
 996         r = read_one_line_file(p, &line);
 997         if (r < 0)
 998                 return r;
 999
1000         p = strrchr(line, ')');
1001         if (!p)
1002                 return -EIO;
1003
1004         p++;
1005
1006         if (sscanf(p, " "
1007                    "%*c "  /* state */
1008                    "%*d "  /* ppid */
1009                    "%*d "  /* pgrp */
1010                    "%*d "  /* session */
1011                    "%lu ", /* ttynr */
1012                    &ttynr) != 1)
1013                 return -EIO;
1014
1015         if (major(ttynr) == 0 && minor(ttynr) == 0)
1016                 return -ENXIO;
1017
1018         if (d)
1019                 *d = (dev_t) ttynr;
1020
1021         return 0;
1022 }
1023
1024 int get_ctty(pid_t pid, dev_t *_devnr, char **r) {
1025         char fn[sizeof("/dev/char/")-1 + 2*DECIMAL_STR_MAX(unsigned) + 1 + 1], *b = NULL;
1026         _cleanup_free_ char *s = NULL;
1027         const char *p;
1028         dev_t devnr;
1029         int k;
1030
1031         assert(r);
1032
1033         k = get_ctty_devnr(pid, &devnr);
1034         if (k < 0)
1035                 return k;
1036
1037         sprintf(fn, "/dev/char/%u:%u", major(devnr), minor(devnr));
1038
1039         k = readlink_malloc(fn, &s);
1040         if (k < 0) {
1041
1042                 if (k != -ENOENT)
1043                         return k;
1044
1045                 /* This is an ugly hack */
1046                 if (major(devnr) == 136) {
1047                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
1048                                 return -ENOMEM;
1049                 } else {
1050                         /* Probably something like the ptys which have no
1051                          * symlink in /dev/char. Let's return something
1052                          * vaguely useful. */
1053
1054                         b = strdup(fn + 5);
1055                         if (!b)
1056                                 return -ENOMEM;
1057                 }
1058         } else {
1059                 if (startswith(s, "/dev/"))
1060                         p = s + 5;
1061                 else if (startswith(s, "../"))
1062                         p = s + 3;
1063                 else
1064                         p = s;
1065
1066                 b = strdup(p);
1067                 if (!b)
1068                         return -ENOMEM;
1069         }
1070
1071         *r = b;
1072         if (_devnr)
1073                 *_devnr = devnr;
1074
1075         return 0;
1076 }