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 <errno.h>
  21 #include <fcntl.h>
  22 #include <limits.h>
  23 #include <stdarg.h>
  24 #include <stddef.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/inotify.h>
  28 #include <sys/socket.h>
  29 #include <sys/sysmacros.h>
  30 #include <sys/time.h>
  31 #include <linux/kd.h>
  32 #include <linux/tiocl.h>
  33 #include <linux/vt.h>
  34 #include <poll.h>
  35 #include <signal.h>
  36 #include <sys/ioctl.h>
  37 #include <sys/types.h>
  38 #include <termios.h>
  39 #include <unistd.h>
  40
  41 #include "alloc-util.h"
  42 #include "env-util.h"
  43 #include "fd-util.h"
  44 #include "fileio.h"
  45 #include "fs-util.h"
  46 #include "io-util.h"
  47 #include "log.h"
  48 #include "macro.h"
  49 #include "parse-util.h"
  50 #include "process-util.h"
  51 #include "socket-util.h"
  52 #include "stat-util.h"
  53 #include "string-util.h"
  54 #include "strv.h"
  55 #include "terminal-util.h"
  56 #include "time-util.h"
  57 #include "util.h"
  58
  59 static volatile unsigned cached_columns = 0;
  60 static volatile unsigned cached_lines = 0;
  61
  62 int chvt(int vt) {
  63         _cleanup_close_ int fd;
  64
  65         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
  66         if (fd < 0)
  67                 return -errno;
  68
  69         if (vt <= 0) {
  70                 int tiocl[2] = {
  71                         TIOCL_GETKMSGREDIRECT,
  72                         0
  73                 };
  74
  75                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  76                         return -errno;
  77
  78                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  79         }
  80
  81         if (ioctl(fd, VT_ACTIVATE, vt) < 0)
  82                 return -errno;
  83
  84         return 0;
  85 }
  86
  87 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  88         struct termios old_termios, new_termios;
  89         char c, line[LINE_MAX];
  90
  91         assert(f);
  92         assert(ret);
  93
  94         if (tcgetattr(fileno(f), &old_termios) >= 0) {
  95                 new_termios = old_termios;
  96
  97                 new_termios.c_lflag &= ~ICANON;
  98                 new_termios.c_cc[VMIN] = 1;
  99                 new_termios.c_cc[VTIME] = 0;
 100
 101                 if (tcsetattr(fileno(f), TCSADRAIN, &new_termios) >= 0) {
 102                         size_t k;
 103
 104                         if (t != USEC_INFINITY) {
 105                                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0) {
 106                                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 107                                         return -ETIMEDOUT;
 108                                 }
 109                         }
 110
 111                         k = fread(&c, 1, 1, f);
 112
 113                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 114
 115                         if (k <= 0)
 116                                 return -EIO;
 117
 118                         if (need_nl)
 119                                 *need_nl = c != '\n';
 120
 121                         *ret = c;
 122                         return 0;
 123                 }
 124         }
 125
 126         if (t != USEC_INFINITY) {
 127                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
 128                         return -ETIMEDOUT;
 129         }
 130
 131         errno = 0;
 132         if (!fgets(line, sizeof(line), f))
 133                 return errno > 0 ? -errno : -EIO;
 134
 135         truncate_nl(line);
 136
 137         if (strlen(line) != 1)
 138                 return -EBADMSG;
 139
 140         if (need_nl)
 141                 *need_nl = false;
 142
 143         *ret = line[0];
 144         return 0;
 145 }
 146
 147 int ask_char(char *ret, const char *replies, const char *text, ...) {
 148         int r;
 149
 150         assert(ret);
 151         assert(replies);
 152         assert(text);
 153
 154         for (;;) {
 155                 va_list ap;
 156                 char c;
 157                 bool need_nl = true;
 158
 159                 if (colors_enabled())
 160                         fputs(ANSI_HIGHLIGHT, stdout);
 161
 162                 va_start(ap, text);
 163                 vprintf(text, ap);
 164                 va_end(ap);
 165
 166                 if (colors_enabled())
 167                         fputs(ANSI_NORMAL, stdout);
 168
 169                 fflush(stdout);
 170
 171                 r = read_one_char(stdin, &c, USEC_INFINITY, &need_nl);
 172                 if (r < 0) {
 173
 174                         if (r == -EBADMSG) {
 175                                 puts("Bad input, please try again.");
 176                                 continue;
 177                         }
 178
 179                         putchar('\n');
 180                         return r;
 181                 }
 182
 183                 if (need_nl)
 184                         putchar('\n');
 185
 186                 if (strchr(replies, c)) {
 187                         *ret = c;
 188                         return 0;
 189                 }
 190
 191                 puts("Read unexpected character, please try again.");
 192         }
 193 }
 194
 195 int ask_string(char **ret, const char *text, ...) {
 196         assert(ret);
 197         assert(text);
 198
 199         for (;;) {
 200                 char line[LINE_MAX];
 201                 va_list ap;
 202
 203                 if (colors_enabled())
 204                         fputs(ANSI_HIGHLIGHT, stdout);
 205
 206                 va_start(ap, text);
 207                 vprintf(text, ap);
 208                 va_end(ap);
 209
 210                 if (colors_enabled())
 211                         fputs(ANSI_NORMAL, stdout);
 212
 213                 fflush(stdout);
 214
 215                 errno = 0;
 216                 if (!fgets(line, sizeof(line), stdin))
 217                         return errno > 0 ? -errno : -EIO;
 218
 219                 if (!endswith(line, "\n"))
 220                         putchar('\n');
 221                 else {
 222                         char *s;
 223
 224                         if (isempty(line))
 225                                 continue;
 226
 227                         truncate_nl(line);
 228                         s = strdup(line);
 229                         if (!s)
 230                                 return -ENOMEM;
 231
 232                         *ret = s;
 233                         return 0;
 234                 }
 235         }
 236 }
 237
 238 int reset_terminal_fd(int fd, bool switch_to_text) {
 239         struct termios termios;
 240         int r = 0;
 241
 242         /* Set terminal to some sane defaults */
 243
 244         assert(fd >= 0);
 245
 246         /* We leave locked terminal attributes untouched, so that
 247          * Plymouth may set whatever it wants to set, and we don't
 248          * interfere with that. */
 249
 250         /* Disable exclusive mode, just in case */
 251         (void) ioctl(fd, TIOCNXCL);
 252
 253         /* Switch to text mode */
 254         if (switch_to_text)
 255                 (void) ioctl(fd, KDSETMODE, KD_TEXT);
 256
 257         /* Enable console unicode mode */
 258         (void) ioctl(fd, KDSKBMODE, K_UNICODE);
 259
 260         if (tcgetattr(fd, &termios) < 0) {
 261                 r = -errno;
 262                 goto finish;
 263         }
 264
 265         /* We only reset the stuff that matters to the software. How
 266          * hardware is set up we don't touch assuming that somebody
 267          * else will do that for us */
 268
 269         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 270         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 271         termios.c_oflag |= ONLCR;
 272         termios.c_cflag |= CREAD;
 273         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 274
 275         termios.c_cc[VINTR]    =   03;  /* ^C */
 276         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 277         termios.c_cc[VERASE]   = 0177;
 278         termios.c_cc[VKILL]    =  025;  /* ^X */
 279         termios.c_cc[VEOF]     =   04;  /* ^D */
 280         termios.c_cc[VSTART]   =  021;  /* ^Q */
 281         termios.c_cc[VSTOP]    =  023;  /* ^S */
 282         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 283         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 284         termios.c_cc[VWERASE]  =  027;  /* ^W */
 285         termios.c_cc[VREPRINT] =  022;  /* ^R */
 286         termios.c_cc[VEOL]     =    0;
 287         termios.c_cc[VEOL2]    =    0;
 288
 289         termios.c_cc[VTIME]  = 0;
 290         termios.c_cc[VMIN]   = 1;
 291
 292         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 293                 r = -errno;
 294
 295 finish:
 296         /* Just in case, flush all crap out */
 297         (void) tcflush(fd, TCIOFLUSH);
 298
 299         return r;
 300 }
 301
 302 int reset_terminal(const char *name) {
 303         _cleanup_close_ int fd = -1;
 304
 305         /* We open the terminal with O_NONBLOCK here, to ensure we
 306          * don't block on carrier if this is a terminal with carrier
 307          * configured. */
 308
 309         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 310         if (fd < 0)
 311                 return fd;
 312
 313         return reset_terminal_fd(fd, true);
 314 }
 315
 316 int open_terminal(const char *name, int mode) {
 317         int fd, r;
 318         unsigned c = 0;
 319
 320         /*
 321          * If a TTY is in the process of being closed opening it might
 322          * cause EIO. This is horribly awful, but unlikely to be
 323          * changed in the kernel. Hence we work around this problem by
 324          * retrying a couple of times.
 325          *
 326          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 327          */
 328
 329         if (mode & O_CREAT)
 330                 return -EINVAL;
 331
 332         for (;;) {
 333                 fd = open(name, mode, 0);
 334                 if (fd >= 0)
 335                         break;
 336
 337                 if (errno != EIO)
 338                         return -errno;
 339
 340                 /* Max 1s in total */
 341                 if (c >= 20)
 342                         return -errno;
 343
 344                 usleep(50 * USEC_PER_MSEC);
 345                 c++;
 346         }
 347
 348         r = isatty(fd);
 349         if (r == 0) {
 350                 safe_close(fd);
 351                 return -ENOTTY;
 352         }
 353
 354         return fd;
 355 }
 356
 357 int acquire_terminal(
 358                 const char *name,
 359                 bool fail,
 360                 bool force,
 361                 bool ignore_tiocstty_eperm,
 362                 usec_t timeout) {
 363
 364         int fd = -1, notify = -1, r = 0, wd = -1;
 365         usec_t ts = 0;
 366
 367         assert(name);
 368
 369         /* We use inotify to be notified when the tty is closed. We
 370          * create the watch before checking if we can actually acquire
 371          * it, so that we don't lose any event.
 372          *
 373          * Note: strictly speaking this actually watches for the
 374          * device being closed, it does *not* really watch whether a
 375          * tty loses its controlling process. However, unless some
 376          * rogue process uses TIOCNOTTY on /dev/tty *after* closing
 377          * its tty otherwise this will not become a problem. As long
 378          * as the administrator makes sure not configure any service
 379          * on the same tty as an untrusted user this should not be a
 380          * problem. (Which he probably should not do anyway.) */
 381
 382         if (timeout != USEC_INFINITY)
 383                 ts = now(CLOCK_MONOTONIC);
 384
 385         if (!fail && !force) {
 386                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 387                 if (notify < 0) {
 388                         r = -errno;
 389                         goto fail;
 390                 }
 391
 392                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 393                 if (wd < 0) {
 394                         r = -errno;
 395                         goto fail;
 396                 }
 397         }
 398
 399         for (;;) {
 400                 struct sigaction sa_old, sa_new = {
 401                         .sa_handler = SIG_IGN,
 402                         .sa_flags = SA_RESTART,
 403                 };
 404
 405                 if (notify >= 0) {
 406                         r = flush_fd(notify);
 407                         if (r < 0)
 408                                 goto fail;
 409                 }
 410
 411                 /* We pass here O_NOCTTY only so that we can check the return
 412                  * value TIOCSCTTY and have a reliable way to figure out if we
 413                  * successfully became the controlling process of the tty */
 414                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 415                 if (fd < 0)
 416                         return fd;
 417
 418                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 419                  * if we already own the tty. */
 420                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 421
 422                 /* First, try to get the tty */
 423                 if (ioctl(fd, TIOCSCTTY, force) < 0)
 424                         r = -errno;
 425
 426                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 427
 428                 /* Sometimes, it makes sense to ignore TIOCSCTTY
 429                  * returning EPERM, i.e. when very likely we already
 430                  * are have this controlling terminal. */
 431                 if (r < 0 && r == -EPERM && ignore_tiocstty_eperm)
 432                         r = 0;
 433
 434                 if (r < 0 && (force || fail || r != -EPERM))
 435                         goto fail;
 436
 437                 if (r >= 0)
 438                         break;
 439
 440                 assert(!fail);
 441                 assert(!force);
 442                 assert(notify >= 0);
 443
 444                 for (;;) {
 445                         union inotify_event_buffer buffer;
 446                         struct inotify_event *e;
 447                         ssize_t l;
 448
 449                         if (timeout != USEC_INFINITY) {
 450                                 usec_t n;
 451
 452                                 n = now(CLOCK_MONOTONIC);
 453                                 if (ts + timeout < n) {
 454                                         r = -ETIMEDOUT;
 455                                         goto fail;
 456                                 }
 457
 458                                 r = fd_wait_for_event(fd, POLLIN, ts + timeout - n);
 459                                 if (r < 0)
 460                                         goto fail;
 461
 462                                 if (r == 0) {
 463                                         r = -ETIMEDOUT;
 464                                         goto fail;
 465                                 }
 466                         }
 467
 468                         l = read(notify, &buffer, sizeof(buffer));
 469                         if (l < 0) {
 470                                 if (errno == EINTR || errno == EAGAIN)
 471                                         continue;
 472
 473                                 r = -errno;
 474                                 goto fail;
 475                         }
 476
 477                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 478                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) {
 479                                         r = -EIO;
 480                                         goto fail;
 481                                 }
 482                         }
 483
 484                         break;
 485                 }
 486
 487                 /* We close the tty fd here since if the old session
 488                  * ended our handle will be dead. It's important that
 489                  * we do this after sleeping, so that we don't enter
 490                  * an endless loop. */
 491                 fd = safe_close(fd);
 492         }
 493
 494         safe_close(notify);
 495
 496         return fd;
 497
 498 fail:
 499         safe_close(fd);
 500         safe_close(notify);
 501
 502         return r;
 503 }
 504
 505 int release_terminal(void) {
 506         static const struct sigaction sa_new = {
 507                 .sa_handler = SIG_IGN,
 508                 .sa_flags = SA_RESTART,
 509         };
 510
 511         _cleanup_close_ int fd = -1;
 512         struct sigaction sa_old;
 513         int r = 0;
 514
 515         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 516         if (fd < 0)
 517                 return -errno;
 518
 519         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 520          * by our own TIOCNOTTY */
 521         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 522
 523         if (ioctl(fd, TIOCNOTTY) < 0)
 524                 r = -errno;
 525
 526         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 527
 528         return r;
 529 }
 530
 531 int terminal_vhangup_fd(int fd) {
 532         assert(fd >= 0);
 533
 534         if (ioctl(fd, TIOCVHANGUP) < 0)
 535                 return -errno;
 536
 537         return 0;
 538 }
 539
 540 int terminal_vhangup(const char *name) {
 541         _cleanup_close_ int fd;
 542
 543         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 544         if (fd < 0)
 545                 return fd;
 546
 547         return terminal_vhangup_fd(fd);
 548 }
 549
 550 int vt_disallocate(const char *name) {
 551         _cleanup_close_ int fd = -1;
 552         unsigned u;
 553         int r;
 554
 555         /* Deallocate the VT if possible. If not possible
 556          * (i.e. because it is the active one), at least clear it
 557          * entirely (including the scrollback buffer) */
 558
 559         if (!startswith(name, "/dev/"))
 560                 return -EINVAL;
 561
 562         if (!tty_is_vc(name)) {
 563                 /* So this is not a VT. I guess we cannot deallocate
 564                  * it then. But let's at least clear the screen */
 565
 566                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 567                 if (fd < 0)
 568                         return fd;
 569
 570                 loop_write(fd,
 571                            "\033[r"    /* clear scrolling region */
 572                            "\033[H"    /* move home */
 573                            "\033[2J",  /* clear screen */
 574                            10, false);
 575                 return 0;
 576         }
 577
 578         if (!startswith(name, "/dev/tty"))
 579                 return -EINVAL;
 580
 581         r = safe_atou(name+8, &u);
 582         if (r < 0)
 583                 return r;
 584
 585         if (u <= 0)
 586                 return -EINVAL;
 587
 588         /* Try to deallocate */
 589         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 590         if (fd < 0)
 591                 return fd;
 592
 593         r = ioctl(fd, VT_DISALLOCATE, u);
 594         fd = safe_close(fd);
 595
 596         if (r >= 0)
 597                 return 0;
 598
 599         if (errno != EBUSY)
 600                 return -errno;
 601
 602         /* Couldn't deallocate, so let's clear it fully with
 603          * scrollback */
 604         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 605         if (fd < 0)
 606                 return fd;
 607
 608         loop_write(fd,
 609                    "\033[r"   /* clear scrolling region */
 610                    "\033[H"   /* move home */
 611                    "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 612                    10, false);
 613         return 0;
 614 }
 615
 616 int make_console_stdio(void) {
 617         int fd, r;
 618
 619         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 620
 621         fd = acquire_terminal("/dev/console", false, true, true, USEC_INFINITY);
 622         if (fd < 0)
 623                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 624
 625         r = reset_terminal_fd(fd, true);
 626         if (r < 0)
 627                 log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 628
 629         r = make_stdio(fd);
 630         if (r < 0)
 631                 return log_error_errno(r, "Failed to duplicate terminal fd: %m");
 632
 633         return 0;
 634 }
 635
 636 bool tty_is_vc(const char *tty) {
 637         assert(tty);
 638
 639         return vtnr_from_tty(tty) >= 0;
 640 }
 641
 642 bool tty_is_console(const char *tty) {
 643         assert(tty);
 644
 645         if (startswith(tty, "/dev/"))
 646                 tty += 5;
 647
 648         return streq(tty, "console");
 649 }
 650
 651 int vtnr_from_tty(const char *tty) {
 652         int i, r;
 653
 654         assert(tty);
 655
 656         if (startswith(tty, "/dev/"))
 657                 tty += 5;
 658
 659         if (!startswith(tty, "tty") )
 660                 return -EINVAL;
 661
 662         if (tty[3] < '0' || tty[3] > '9')
 663                 return -EINVAL;
 664
 665         r = safe_atoi(tty+3, &i);
 666         if (r < 0)
 667                 return r;
 668
 669         if (i < 0 || i > 63)
 670                 return -EINVAL;
 671
 672         return i;
 673 }
 674
 675 char *resolve_dev_console(char **active) {
 676         char *tty;
 677
 678         /* Resolve where /dev/console is pointing to, if /sys is actually ours
 679          * (i.e. not read-only-mounted which is a sign for container setups) */
 680
 681         if (path_is_read_only_fs("/sys") > 0)
 682                 return NULL;
 683
 684         if (read_one_line_file("/sys/class/tty/console/active", active) < 0)
 685                 return NULL;
 686
 687         /* If multiple log outputs are configured the last one is what
 688          * /dev/console points to */
 689         tty = strrchr(*active, ' ');
 690         if (tty)
 691                 tty++;
 692         else
 693                 tty = *active;
 694
 695         if (streq(tty, "tty0")) {
 696                 char *tmp;
 697
 698                 /* Get the active VC (e.g. tty1) */
 699                 if (read_one_line_file("/sys/class/tty/tty0/active", &tmp) >= 0) {
 700                         free(*active);
 701                         tty = *active = tmp;
 702                 }
 703         }
 704
 705         return tty;
 706 }
 707
 708 int get_kernel_consoles(char ***consoles) {
 709         _cleanup_strv_free_ char **con = NULL;
 710         _cleanup_free_ char *line = NULL;
 711         const char *active;
 712         int r;
 713
 714         assert(consoles);
 715
 716         r = read_one_line_file("/sys/class/tty/console/active", &line);
 717         if (r < 0)
 718                 return r;
 719
 720         active = line;
 721         for (;;) {
 722                 _cleanup_free_ char *tty = NULL;
 723                 char *path;
 724
 725                 r = extract_first_word(&active, &tty, NULL, 0);
 726                 if (r < 0)
 727                         return r;
 728                 if (r == 0)
 729                         break;
 730
 731                 if (streq(tty, "tty0")) {
 732                         tty = mfree(tty);
 733                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 734                         if (r < 0)
 735                                 return r;
 736                 }
 737
 738                 path = strappend("/dev/", tty);
 739                 if (!path)
 740                         return -ENOMEM;
 741
 742                 if (access(path, F_OK) < 0) {
 743                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 744                         free(path);
 745                         continue;
 746                 }
 747
 748                 r = strv_consume(&con, path);
 749                 if (r < 0)
 750                         return r;
 751         }
 752
 753         if (strv_isempty(con)) {
 754                 log_debug("No devices found for system console");
 755
 756                 r = strv_extend(&con, "/dev/console");
 757                 if (r < 0)
 758                         return r;
 759         }
 760
 761         *consoles = con;
 762         con = NULL;
 763         return 0;
 764 }
 765
 766 bool tty_is_vc_resolve(const char *tty) {
 767         _cleanup_free_ char *active = NULL;
 768
 769         assert(tty);
 770
 771         if (startswith(tty, "/dev/"))
 772                 tty += 5;
 773
 774         if (streq(tty, "console")) {
 775                 tty = resolve_dev_console(&active);
 776                 if (!tty)
 777                         return false;
 778         }
 779
 780         return tty_is_vc(tty);
 781 }
 782
 783 const char *default_term_for_tty(const char *tty) {
 784         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 785 }
 786
 787 int fd_columns(int fd) {
 788         struct winsize ws = {};
 789
 790         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 791                 return -errno;
 792
 793         if (ws.ws_col <= 0)
 794                 return -EIO;
 795
 796         return ws.ws_col;
 797 }
 798
 799 unsigned columns(void) {
 800         const char *e;
 801         int c;
 802
 803         if (_likely_(cached_columns > 0))
 804                 return cached_columns;
 805
 806         c = 0;
 807         e = getenv("COLUMNS");
 808         if (e)
 809                 (void) safe_atoi(e, &c);
 810
 811         if (c <= 0)
 812                 c = fd_columns(STDOUT_FILENO);
 813
 814         if (c <= 0)
 815                 c = 80;
 816
 817         cached_columns = c;
 818         return cached_columns;
 819 }
 820
 821 int fd_lines(int fd) {
 822         struct winsize ws = {};
 823
 824         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 825                 return -errno;
 826
 827         if (ws.ws_row <= 0)
 828                 return -EIO;
 829
 830         return ws.ws_row;
 831 }
 832
 833 unsigned lines(void) {
 834         const char *e;
 835         int l;
 836
 837         if (_likely_(cached_lines > 0))
 838                 return cached_lines;
 839
 840         l = 0;
 841         e = getenv("LINES");
 842         if (e)
 843                 (void) safe_atoi(e, &l);
 844
 845         if (l <= 0)
 846                 l = fd_lines(STDOUT_FILENO);
 847
 848         if (l <= 0)
 849                 l = 24;
 850
 851         cached_lines = l;
 852         return cached_lines;
 853 }
 854
 855 /* intended to be used as a SIGWINCH sighandler */
 856 void columns_lines_cache_reset(int signum) {
 857         cached_columns = 0;
 858         cached_lines = 0;
 859 }
 860
 861 bool on_tty(void) {
 862         static int cached_on_tty = -1;
 863
 864         if (_unlikely_(cached_on_tty < 0))
 865                 cached_on_tty = isatty(STDOUT_FILENO) > 0;
 866
 867         return cached_on_tty;
 868 }
 869
 870 int make_stdio(int fd) {
 871         int r, s, t;
 872
 873         assert(fd >= 0);
 874
 875         r = dup2(fd, STDIN_FILENO);
 876         s = dup2(fd, STDOUT_FILENO);
 877         t = dup2(fd, STDERR_FILENO);
 878
 879         if (fd >= 3)
 880                 safe_close(fd);
 881
 882         if (r < 0 || s < 0 || t < 0)
 883                 return -errno;
 884
 885         /* Explicitly unset O_CLOEXEC, since if fd was < 3, then
 886          * dup2() was a NOP and the bit hence possibly set. */
 887         stdio_unset_cloexec();
 888
 889         return 0;
 890 }
 891
 892 int make_null_stdio(void) {
 893         int null_fd;
 894
 895         null_fd = open("/dev/null", O_RDWR|O_NOCTTY);
 896         if (null_fd < 0)
 897                 return -errno;
 898
 899         return make_stdio(null_fd);
 900 }
 901
 902 int getttyname_malloc(int fd, char **ret) {
 903         size_t l = 100;
 904         int r;
 905
 906         assert(fd >= 0);
 907         assert(ret);
 908
 909         for (;;) {
 910                 char path[l];
 911
 912                 r = ttyname_r(fd, path, sizeof(path));
 913                 if (r == 0) {
 914                         const char *p;
 915                         char *c;
 916
 917                         p = startswith(path, "/dev/");
 918                         c = strdup(p ?: path);
 919                         if (!c)
 920                                 return -ENOMEM;
 921
 922                         *ret = c;
 923                         return 0;
 924                 }
 925
 926                 if (r != ERANGE)
 927                         return -r;
 928
 929                 l *= 2;
 930         }
 931
 932         return 0;
 933 }
 934
 935 int getttyname_harder(int fd, char **r) {
 936         int k;
 937         char *s = NULL;
 938
 939         k = getttyname_malloc(fd, &s);
 940         if (k < 0)
 941                 return k;
 942
 943         if (streq(s, "tty")) {
 944                 free(s);
 945                 return get_ctty(0, NULL, r);
 946         }
 947
 948         *r = s;
 949         return 0;
 950 }
 951
 952 int get_ctty_devnr(pid_t pid, dev_t *d) {
 953         int r;
 954         _cleanup_free_ char *line = NULL;
 955         const char *p;
 956         unsigned long ttynr;
 957
 958         assert(pid >= 0);
 959
 960         p = procfs_file_alloca(pid, "stat");
 961         r = read_one_line_file(p, &line);
 962         if (r < 0)
 963                 return r;
 964
 965         p = strrchr(line, ')');
 966         if (!p)
 967                 return -EIO;
 968
 969         p++;
 970
 971         if (sscanf(p, " "
 972                    "%*c "  /* state */
 973                    "%*d "  /* ppid */
 974                    "%*d "  /* pgrp */
 975                    "%*d "  /* session */
 976                    "%lu ", /* ttynr */
 977                    &ttynr) != 1)
 978                 return -EIO;
 979
 980         if (major(ttynr) == 0 && minor(ttynr) == 0)
 981                 return -ENXIO;
 982
 983         if (d)
 984                 *d = (dev_t) ttynr;
 985
 986         return 0;
 987 }
 988
 989 int get_ctty(pid_t pid, dev_t *_devnr, char **r) {
 990         char fn[sizeof("/dev/char/")-1 + 2*DECIMAL_STR_MAX(unsigned) + 1 + 1], *b = NULL;
 991         _cleanup_free_ char *s = NULL;
 992         const char *p;
 993         dev_t devnr;
 994         int k;
 995
 996         assert(r);
 997
 998         k = get_ctty_devnr(pid, &devnr);
 999         if (k < 0)
1000                 return k;
1001
1002         sprintf(fn, "/dev/char/%u:%u", major(devnr), minor(devnr));
1003
1004         k = readlink_malloc(fn, &s);
1005         if (k < 0) {
1006
1007                 if (k != -ENOENT)
1008                         return k;
1009
1010                 /* This is an ugly hack */
1011                 if (major(devnr) == 136) {
1012                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
1013                                 return -ENOMEM;
1014                 } else {
1015                         /* Probably something like the ptys which have no
1016                          * symlink in /dev/char. Let's return something
1017                          * vaguely useful. */
1018
1019                         b = strdup(fn + 5);
1020                         if (!b)
1021                                 return -ENOMEM;
1022                 }
1023         } else {
1024                 if (startswith(s, "/dev/"))
1025                         p = s + 5;
1026                 else if (startswith(s, "../"))
1027                         p = s + 3;
1028                 else
1029                         p = s;
1030
1031                 b = strdup(p);
1032                 if (!b)
1033                         return -ENOMEM;
1034         }
1035
1036         *r = b;
1037         if (_devnr)
1038                 *_devnr = devnr;
1039
1040         return 0;
1041 }
1042
1043 int ptsname_malloc(int fd, char **ret) {
1044         size_t l = 100;
1045
1046         assert(fd >= 0);
1047         assert(ret);
1048
1049         for (;;) {
1050                 char *c;
1051
1052                 c = new(char, l);
1053                 if (!c)
1054                         return -ENOMEM;
1055
1056                 if (ptsname_r(fd, c, l) == 0) {
1057                         *ret = c;
1058                         return 0;
1059                 }
1060                 if (errno != ERANGE) {
1061                         free(c);
1062                         return -errno;
1063                 }
1064
1065                 free(c);
1066                 l *= 2;
1067         }
1068 }
1069
1070 int ptsname_namespace(int pty, char **ret) {
1071         int no = -1, r;
1072
1073         /* Like ptsname(), but doesn't assume that the path is
1074          * accessible in the local namespace. */
1075
1076         r = ioctl(pty, TIOCGPTN, &no);
1077         if (r < 0)
1078                 return -errno;
1079
1080         if (no < 0)
1081                 return -EIO;
1082
1083         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1084                 return -ENOMEM;
1085
1086         return 0;
1087 }
1088
1089 int openpt_in_namespace(pid_t pid, int flags) {
1090         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1091         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1092         siginfo_t si;
1093         pid_t child;
1094         int r;
1095
1096         assert(pid > 0);
1097
1098         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1099         if (r < 0)
1100                 return r;
1101
1102         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1103                 return -errno;
1104
1105         child = fork();
1106         if (child < 0)
1107                 return -errno;
1108
1109         if (child == 0) {
1110                 int master;
1111
1112                 pair[0] = safe_close(pair[0]);
1113
1114                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
1115                 if (r < 0)
1116                         _exit(EXIT_FAILURE);
1117
1118                 master = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1119                 if (master < 0)
1120                         _exit(EXIT_FAILURE);
1121
1122                 if (unlockpt(master) < 0)
1123                         _exit(EXIT_FAILURE);
1124
1125                 if (send_one_fd(pair[1], master, 0) < 0)
1126                         _exit(EXIT_FAILURE);
1127
1128                 _exit(EXIT_SUCCESS);
1129         }
1130
1131         pair[1] = safe_close(pair[1]);
1132
1133         r = wait_for_terminate(child, &si);
1134         if (r < 0)
1135                 return r;
1136         if (si.si_code != CLD_EXITED || si.si_status != EXIT_SUCCESS)
1137                 return -EIO;
1138
1139         return receive_one_fd(pair[0], 0);
1140 }
1141
1142 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1143         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1144         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1145         siginfo_t si;
1146         pid_t child;
1147         int r;
1148
1149         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1150         if (r < 0)
1151                 return r;
1152
1153         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1154                 return -errno;
1155
1156         child = fork();
1157         if (child < 0)
1158                 return -errno;
1159
1160         if (child == 0) {
1161                 int master;
1162
1163                 pair[0] = safe_close(pair[0]);
1164
1165                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
1166                 if (r < 0)
1167                         _exit(EXIT_FAILURE);
1168
1169                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1170                 if (master < 0)
1171                         _exit(EXIT_FAILURE);
1172
1173                 if (send_one_fd(pair[1], master, 0) < 0)
1174                         _exit(EXIT_FAILURE);
1175
1176                 _exit(EXIT_SUCCESS);
1177         }
1178
1179         pair[1] = safe_close(pair[1]);
1180
1181         r = wait_for_terminate(child, &si);
1182         if (r < 0)
1183                 return r;
1184         if (si.si_code != CLD_EXITED || si.si_status != EXIT_SUCCESS)
1185                 return -EIO;
1186
1187         return receive_one_fd(pair[0], 0);
1188 }
1189
1190 static bool getenv_terminal_is_dumb(void) {
1191         const char *e;
1192
1193         e = getenv("TERM");
1194         if (!e)
1195                 return true;
1196
1197         return streq(e, "dumb");
1198 }
1199
1200 bool terminal_is_dumb(void) {
1201         if (!on_tty())
1202                 return true;
1203
1204         return getenv_terminal_is_dumb();
1205 }
1206
1207 bool colors_enabled(void) {
1208         static int enabled = -1;
1209
1210         if (_unlikely_(enabled < 0)) {
1211                 int val;
1212
1213                 val = getenv_bool("SYSTEMD_COLORS");
1214                 if (val >= 0)
1215                         enabled = val;
1216                 else if (getpid() == 1)
1217                         /* PID1 outputs to the console without holding it open all the time */
1218                         enabled = !getenv_terminal_is_dumb();
1219                 else
1220                         enabled = !terminal_is_dumb();
1221         }
1222
1223         return enabled;
1224 }