src/basic/terminal-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2010 Lennart Poettering
   4 ***/
   5
   6 #include <errno.h>
   7 #include <fcntl.h>
   8 #include <limits.h>
   9 #include <linux/kd.h>
  10 #include <linux/tiocl.h>
  11 #include <linux/vt.h>
  12 #include <poll.h>
  13 #include <signal.h>
  14 #include <stdarg.h>
  15 #include <stddef.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <sys/inotify.h>
  19 #include <sys/ioctl.h>
  20 #include <sys/socket.h>
  21 #include <sys/sysmacros.h>
  22 #include <sys/time.h>
  23 #include <sys/types.h>
  24 #include <sys/utsname.h>
  25 #include <termios.h>
  26 #include <unistd.h>
  27
  28 #include "alloc-util.h"
  29 #include "copy.h"
  30 #include "def.h"
  31 #include "env-util.h"
  32 #include "fd-util.h"
  33 #include "fileio.h"
  34 #include "fs-util.h"
  35 #include "io-util.h"
  36 #include "log.h"
  37 #include "macro.h"
  38 #include "pager.h"
  39 #include "parse-util.h"
  40 #include "path-util.h"
  41 #include "proc-cmdline.h"
  42 #include "process-util.h"
  43 #include "socket-util.h"
  44 #include "stat-util.h"
  45 #include "string-util.h"
  46 #include "strv.h"
  47 #include "terminal-util.h"
  48 #include "time-util.h"
  49 #include "util.h"
  50
  51 static volatile unsigned cached_columns = 0;
  52 static volatile unsigned cached_lines = 0;
  53
  54 static volatile int cached_on_tty = -1;
  55 static volatile int cached_colors_enabled = -1;
  56 static volatile int cached_underline_enabled = -1;
  57
  58 int chvt(int vt) {
  59         _cleanup_close_ int fd;
  60
  61         /* Switch to the specified vt number. If the VT is specified <= 0 switch to the VT the kernel log messages go,
  62          * if that's configured. */
  63
  64         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
  65         if (fd < 0)
  66                 return -errno;
  67
  68         if (vt <= 0) {
  69                 int tiocl[2] = {
  70                         TIOCL_GETKMSGREDIRECT,
  71                         0
  72                 };
  73
  74                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  75                         return -errno;
  76
  77                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  78         }
  79
  80         if (ioctl(fd, VT_ACTIVATE, vt) < 0)
  81                 return -errno;
  82
  83         return 0;
  84 }
  85
  86 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  87         struct termios old_termios, new_termios;
  88         char c, line[LINE_MAX];
  89
  90         assert(f);
  91         assert(ret);
  92
  93         if (tcgetattr(fileno(f), &old_termios) >= 0) {
  94                 new_termios = old_termios;
  95
  96                 new_termios.c_lflag &= ~ICANON;
  97                 new_termios.c_cc[VMIN] = 1;
  98                 new_termios.c_cc[VTIME] = 0;
  99
 100                 if (tcsetattr(fileno(f), TCSADRAIN, &new_termios) >= 0) {
 101                         size_t k;
 102
 103                         if (t != USEC_INFINITY) {
 104                                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0) {
 105                                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 106                                         return -ETIMEDOUT;
 107                                 }
 108                         }
 109
 110                         k = fread(&c, 1, 1, f);
 111
 112                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 113
 114                         if (k <= 0)
 115                                 return -EIO;
 116
 117                         if (need_nl)
 118                                 *need_nl = c != '\n';
 119
 120                         *ret = c;
 121                         return 0;
 122                 }
 123         }
 124
 125         if (t != USEC_INFINITY) {
 126                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
 127                         return -ETIMEDOUT;
 128         }
 129
 130         errno = 0;
 131         if (!fgets(line, sizeof(line), f))
 132                 return errno > 0 ? -errno : -EIO;
 133
 134         truncate_nl(line);
 135
 136         if (strlen(line) != 1)
 137                 return -EBADMSG;
 138
 139         if (need_nl)
 140                 *need_nl = false;
 141
 142         *ret = line[0];
 143         return 0;
 144 }
 145
 146 #define DEFAULT_ASK_REFRESH_USEC (2*USEC_PER_SEC)
 147
 148 int ask_char(char *ret, const char *replies, const char *fmt, ...) {
 149         int r;
 150
 151         assert(ret);
 152         assert(replies);
 153         assert(fmt);
 154
 155         for (;;) {
 156                 va_list ap;
 157                 char c;
 158                 bool need_nl = true;
 159
 160                 if (colors_enabled())
 161                         fputs(ANSI_HIGHLIGHT, stdout);
 162
 163                 putchar('\r');
 164
 165                 va_start(ap, fmt);
 166                 vprintf(fmt, ap);
 167                 va_end(ap);
 168
 169                 if (colors_enabled())
 170                         fputs(ANSI_NORMAL, stdout);
 171
 172                 fflush(stdout);
 173
 174                 r = read_one_char(stdin, &c, DEFAULT_ASK_REFRESH_USEC, &need_nl);
 175                 if (r < 0) {
 176
 177                         if (r == -ETIMEDOUT)
 178                                 continue;
 179
 180                         if (r == -EBADMSG) {
 181                                 puts("Bad input, please try again.");
 182                                 continue;
 183                         }
 184
 185                         putchar('\n');
 186                         return r;
 187                 }
 188
 189                 if (need_nl)
 190                         putchar('\n');
 191
 192                 if (strchr(replies, c)) {
 193                         *ret = c;
 194                         return 0;
 195                 }
 196
 197                 puts("Read unexpected character, please try again.");
 198         }
 199 }
 200
 201 int ask_string(char **ret, const char *text, ...) {
 202         assert(ret);
 203         assert(text);
 204
 205         for (;;) {
 206                 char line[LINE_MAX];
 207                 va_list ap;
 208
 209                 if (colors_enabled())
 210                         fputs(ANSI_HIGHLIGHT, stdout);
 211
 212                 va_start(ap, text);
 213                 vprintf(text, ap);
 214                 va_end(ap);
 215
 216                 if (colors_enabled())
 217                         fputs(ANSI_NORMAL, stdout);
 218
 219                 fflush(stdout);
 220
 221                 errno = 0;
 222                 if (!fgets(line, sizeof(line), stdin))
 223                         return errno > 0 ? -errno : -EIO;
 224
 225                 if (!endswith(line, "\n"))
 226                         putchar('\n');
 227                 else {
 228                         char *s;
 229
 230                         if (isempty(line))
 231                                 continue;
 232
 233                         truncate_nl(line);
 234                         s = strdup(line);
 235                         if (!s)
 236                                 return -ENOMEM;
 237
 238                         *ret = s;
 239                         return 0;
 240                 }
 241         }
 242 }
 243
 244 int reset_terminal_fd(int fd, bool switch_to_text) {
 245         struct termios termios;
 246         int r = 0;
 247
 248         /* Set terminal to some sane defaults */
 249
 250         assert(fd >= 0);
 251
 252         /* We leave locked terminal attributes untouched, so that
 253          * Plymouth may set whatever it wants to set, and we don't
 254          * interfere with that. */
 255
 256         /* Disable exclusive mode, just in case */
 257         (void) ioctl(fd, TIOCNXCL);
 258
 259         /* Switch to text mode */
 260         if (switch_to_text)
 261                 (void) ioctl(fd, KDSETMODE, KD_TEXT);
 262
 263         /* Set default keyboard mode */
 264         (void) vt_reset_keyboard(fd);
 265
 266         if (tcgetattr(fd, &termios) < 0) {
 267                 r = -errno;
 268                 goto finish;
 269         }
 270
 271         /* We only reset the stuff that matters to the software. How
 272          * hardware is set up we don't touch assuming that somebody
 273          * else will do that for us */
 274
 275         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 276         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 277         termios.c_oflag |= ONLCR;
 278         termios.c_cflag |= CREAD;
 279         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 280
 281         termios.c_cc[VINTR]    =   03;  /* ^C */
 282         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 283         termios.c_cc[VERASE]   = 0177;
 284         termios.c_cc[VKILL]    =  025;  /* ^X */
 285         termios.c_cc[VEOF]     =   04;  /* ^D */
 286         termios.c_cc[VSTART]   =  021;  /* ^Q */
 287         termios.c_cc[VSTOP]    =  023;  /* ^S */
 288         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 289         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 290         termios.c_cc[VWERASE]  =  027;  /* ^W */
 291         termios.c_cc[VREPRINT] =  022;  /* ^R */
 292         termios.c_cc[VEOL]     =    0;
 293         termios.c_cc[VEOL2]    =    0;
 294
 295         termios.c_cc[VTIME]  = 0;
 296         termios.c_cc[VMIN]   = 1;
 297
 298         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 299                 r = -errno;
 300
 301 finish:
 302         /* Just in case, flush all crap out */
 303         (void) tcflush(fd, TCIOFLUSH);
 304
 305         return r;
 306 }
 307
 308 int reset_terminal(const char *name) {
 309         _cleanup_close_ int fd = -1;
 310
 311         /* We open the terminal with O_NONBLOCK here, to ensure we
 312          * don't block on carrier if this is a terminal with carrier
 313          * configured. */
 314
 315         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 316         if (fd < 0)
 317                 return fd;
 318
 319         return reset_terminal_fd(fd, true);
 320 }
 321
 322 int open_terminal(const char *name, int mode) {
 323         unsigned c = 0;
 324         int fd;
 325
 326         /*
 327          * If a TTY is in the process of being closed opening it might
 328          * cause EIO. This is horribly awful, but unlikely to be
 329          * changed in the kernel. Hence we work around this problem by
 330          * retrying a couple of times.
 331          *
 332          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 333          */
 334
 335         if (mode & O_CREAT)
 336                 return -EINVAL;
 337
 338         for (;;) {
 339                 fd = open(name, mode, 0);
 340                 if (fd >= 0)
 341                         break;
 342
 343                 if (errno != EIO)
 344                         return -errno;
 345
 346                 /* Max 1s in total */
 347                 if (c >= 20)
 348                         return -errno;
 349
 350                 usleep(50 * USEC_PER_MSEC);
 351                 c++;
 352         }
 353
 354         if (isatty(fd) <= 0) {
 355                 safe_close(fd);
 356                 return -ENOTTY;
 357         }
 358
 359         return fd;
 360 }
 361
 362 int acquire_terminal(
 363                 const char *name,
 364                 AcquireTerminalFlags flags,
 365                 usec_t timeout) {
 366
 367         _cleanup_close_ int notify = -1, fd = -1;
 368         usec_t ts = USEC_INFINITY;
 369         int r, wd = -1;
 370
 371         assert(name);
 372         assert(IN_SET(flags & ~ACQUIRE_TERMINAL_PERMISSIVE, ACQUIRE_TERMINAL_TRY, ACQUIRE_TERMINAL_FORCE, ACQUIRE_TERMINAL_WAIT));
 373
 374         /* We use inotify to be notified when the tty is closed. We create the watch before checking if we can actually
 375          * acquire it, so that we don't lose any event.
 376          *
 377          * Note: strictly speaking this actually watches for the device being closed, it does *not* really watch
 378          * whether a tty loses its controlling process. However, unless some rogue process uses TIOCNOTTY on /dev/tty
 379          * *after* closing its tty otherwise this will not become a problem. As long as the administrator makes sure to
 380          * not configure any service on the same tty as an untrusted user this should not be a problem. (Which they
 381          * probably should not do anyway.) */
 382
 383         if ((flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_WAIT) {
 384                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 385                 if (notify < 0)
 386                         return -errno;
 387
 388                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 389                 if (wd < 0)
 390                         return -errno;
 391
 392                 if (timeout != USEC_INFINITY)
 393                         ts = now(CLOCK_MONOTONIC);
 394         }
 395
 396         for (;;) {
 397                 struct sigaction sa_old, sa_new = {
 398                         .sa_handler = SIG_IGN,
 399                         .sa_flags = SA_RESTART,
 400                 };
 401
 402                 if (notify >= 0) {
 403                         r = flush_fd(notify);
 404                         if (r < 0)
 405                                 return r;
 406                 }
 407
 408                 /* We pass here O_NOCTTY only so that we can check the return value TIOCSCTTY and have a reliable way
 409                  * to figure out if we successfully became the controlling process of the tty */
 410                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 411                 if (fd < 0)
 412                         return fd;
 413
 414                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed if we already own the tty. */
 415                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 416
 417                 /* First, try to get the tty */
 418                 r = ioctl(fd, TIOCSCTTY,
 419                           (flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_FORCE) < 0 ? -errno : 0;
 420
 421                 /* Reset signal handler to old value */
 422                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 423
 424                 /* Success? Exit the loop now! */
 425                 if (r >= 0)
 426                         break;
 427
 428                 /* Any failure besides -EPERM? Fail, regardless of the mode. */
 429                 if (r != -EPERM)
 430                         return r;
 431
 432                 if (flags & ACQUIRE_TERMINAL_PERMISSIVE) /* If we are in permissive mode, then EPERM is fine, turn this
 433                                                           * into a success. Note that EPERM is also returned if we
 434                                                           * already are the owner of the TTY. */
 435                         break;
 436
 437                 if (flags != ACQUIRE_TERMINAL_WAIT) /* If we are in TRY or FORCE mode, then propagate EPERM as EPERM */
 438                         return r;
 439
 440                 assert(notify >= 0);
 441                 assert(wd >= 0);
 442
 443                 for (;;) {
 444                         union inotify_event_buffer buffer;
 445                         struct inotify_event *e;
 446                         ssize_t l;
 447
 448                         if (timeout != USEC_INFINITY) {
 449                                 usec_t n;
 450
 451                                 assert(ts != USEC_INFINITY);
 452
 453                                 n = now(CLOCK_MONOTONIC);
 454                                 if (ts + timeout < n)
 455                                         return -ETIMEDOUT;
 456
 457                                 r = fd_wait_for_event(notify, POLLIN, ts + timeout - n);
 458                                 if (r < 0)
 459                                         return r;
 460                                 if (r == 0)
 461                                         return -ETIMEDOUT;
 462                         }
 463
 464                         l = read(notify, &buffer, sizeof(buffer));
 465                         if (l < 0) {
 466                                 if (IN_SET(errno, EINTR, EAGAIN))
 467                                         continue;
 468
 469                                 return -errno;
 470                         }
 471
 472                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 473                                 if (e->mask & IN_Q_OVERFLOW) /* If we hit an inotify queue overflow, simply check if the terminal is up for grabs now. */
 474                                         break;
 475
 476                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) /* Safety checks */
 477                                         return -EIO;
 478                         }
 479
 480                         break;
 481                 }
 482
 483                 /* We close the tty fd here since if the old session ended our handle will be dead. It's important that
 484                  * we do this after sleeping, so that we don't enter an endless loop. */
 485                 fd = safe_close(fd);
 486         }
 487
 488         return TAKE_FD(fd);
 489 }
 490
 491 int release_terminal(void) {
 492         static const struct sigaction sa_new = {
 493                 .sa_handler = SIG_IGN,
 494                 .sa_flags = SA_RESTART,
 495         };
 496
 497         _cleanup_close_ int fd = -1;
 498         struct sigaction sa_old;
 499         int r;
 500
 501         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 502         if (fd < 0)
 503                 return -errno;
 504
 505         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 506          * by our own TIOCNOTTY */
 507         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 508
 509         r = ioctl(fd, TIOCNOTTY) < 0 ? -errno : 0;
 510
 511         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 512
 513         return r;
 514 }
 515
 516 int terminal_vhangup_fd(int fd) {
 517         assert(fd >= 0);
 518
 519         if (ioctl(fd, TIOCVHANGUP) < 0)
 520                 return -errno;
 521
 522         return 0;
 523 }
 524
 525 int terminal_vhangup(const char *name) {
 526         _cleanup_close_ int fd;
 527
 528         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 529         if (fd < 0)
 530                 return fd;
 531
 532         return terminal_vhangup_fd(fd);
 533 }
 534
 535 int vt_disallocate(const char *name) {
 536         _cleanup_close_ int fd = -1;
 537         const char *e, *n;
 538         unsigned u;
 539         int r;
 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         e = path_startswith(name, "/dev/");
 546         if (!e)
 547                 return -EINVAL;
 548
 549         if (!tty_is_vc(name)) {
 550                 /* So this is not a VT. I guess we cannot deallocate
 551                  * it then. But let's at least clear the screen */
 552
 553                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 554                 if (fd < 0)
 555                         return fd;
 556
 557                 loop_write(fd,
 558                            "\033[r"    /* clear scrolling region */
 559                            "\033[H"    /* move home */
 560                            "\033[2J",  /* clear screen */
 561                            10, false);
 562                 return 0;
 563         }
 564
 565         n = startswith(e, "tty");
 566         if (!n)
 567                 return -EINVAL;
 568
 569         r = safe_atou(n, &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|O_NONBLOCK);
 578         if (fd < 0)
 579                 return fd;
 580
 581         r = ioctl(fd, VT_DISALLOCATE, u);
 582         fd = 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         return 0;
 602 }
 603
 604 int make_console_stdio(void) {
 605         int fd, r;
 606
 607         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 608
 609         fd = acquire_terminal("/dev/console", ACQUIRE_TERMINAL_FORCE|ACQUIRE_TERMINAL_PERMISSIVE, USEC_INFINITY);
 610         if (fd < 0)
 611                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 612
 613         r = reset_terminal_fd(fd, true);
 614         if (r < 0)
 615                 log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 616
 617         r = rearrange_stdio(fd, fd, fd); /* This invalidates 'fd' both on success and on failure. */
 618         if (r < 0)
 619                 return log_error_errno(r, "Failed to make terminal stdin/stdout/stderr: %m");
 620
 621         reset_terminal_feature_caches();
 622
 623         return 0;
 624 }
 625
 626 bool tty_is_vc(const char *tty) {
 627         assert(tty);
 628
 629         return vtnr_from_tty(tty) >= 0;
 630 }
 631
 632 bool tty_is_console(const char *tty) {
 633         assert(tty);
 634
 635         return streq(skip_dev_prefix(tty), "console");
 636 }
 637
 638 int vtnr_from_tty(const char *tty) {
 639         int i, r;
 640
 641         assert(tty);
 642
 643         tty = skip_dev_prefix(tty);
 644
 645         if (!startswith(tty, "tty") )
 646                 return -EINVAL;
 647
 648         if (tty[3] < '0' || tty[3] > '9')
 649                 return -EINVAL;
 650
 651         r = safe_atoi(tty+3, &i);
 652         if (r < 0)
 653                 return r;
 654
 655         if (i < 0 || i > 63)
 656                 return -EINVAL;
 657
 658         return i;
 659 }
 660
 661  int resolve_dev_console(char **ret) {
 662         _cleanup_free_ char *active = NULL;
 663         char *tty;
 664         int r;
 665
 666         assert(ret);
 667
 668         /* Resolve where /dev/console is pointing to, if /sys is actually ours (i.e. not read-only-mounted which is a
 669          * sign for container setups) */
 670
 671         if (path_is_read_only_fs("/sys") > 0)
 672                 return -ENOMEDIUM;
 673
 674         r = read_one_line_file("/sys/class/tty/console/active", &active);
 675         if (r < 0)
 676                 return r;
 677
 678         /* If multiple log outputs are configured the last one is what /dev/console points to */
 679         tty = strrchr(active, ' ');
 680         if (tty)
 681                 tty++;
 682         else
 683                 tty = active;
 684
 685         if (streq(tty, "tty0")) {
 686                 active = mfree(active);
 687
 688                 /* Get the active VC (e.g. tty1) */
 689                 r = read_one_line_file("/sys/class/tty/tty0/active", &active);
 690                 if (r < 0)
 691                         return r;
 692
 693                 tty = active;
 694         }
 695
 696         if (tty == active)
 697                 *ret = TAKE_PTR(active);
 698         else {
 699                 char *tmp;
 700
 701                 tmp = strdup(tty);
 702                 if (!tmp)
 703                         return -ENOMEM;
 704
 705                 *ret = tmp;
 706         }
 707
 708         return 0;
 709 }
 710
 711 int get_kernel_consoles(char ***ret) {
 712         _cleanup_strv_free_ char **l = NULL;
 713         _cleanup_free_ char *line = NULL;
 714         const char *p;
 715         int r;
 716
 717         assert(ret);
 718
 719         /* If /sys is mounted read-only this means we are running in some kind of container environment. In that
 720          * case /sys would reflect the host system, not us, hence ignore the data we can read from it. */
 721         if (path_is_read_only_fs("/sys") > 0)
 722                 goto fallback;
 723
 724         r = read_one_line_file("/sys/class/tty/console/active", &line);
 725         if (r < 0)
 726                 return r;
 727
 728         p = line;
 729         for (;;) {
 730                 _cleanup_free_ char *tty = NULL;
 731                 char *path;
 732
 733                 r = extract_first_word(&p, &tty, NULL, 0);
 734                 if (r < 0)
 735                         return r;
 736                 if (r == 0)
 737                         break;
 738
 739                 if (streq(tty, "tty0")) {
 740                         tty = mfree(tty);
 741                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 742                         if (r < 0)
 743                                 return r;
 744                 }
 745
 746                 path = strappend("/dev/", tty);
 747                 if (!path)
 748                         return -ENOMEM;
 749
 750                 if (access(path, F_OK) < 0) {
 751                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 752                         free(path);
 753                         continue;
 754                 }
 755
 756                 r = strv_consume(&l, path);
 757                 if (r < 0)
 758                         return r;
 759         }
 760
 761         if (strv_isempty(l)) {
 762                 log_debug("No devices found for system console");
 763                 goto fallback;
 764         }
 765
 766         *ret = TAKE_PTR(l);
 767
 768         return 0;
 769
 770 fallback:
 771         r = strv_extend(&l, "/dev/console");
 772         if (r < 0)
 773                 return r;
 774
 775         *ret = TAKE_PTR(l);
 776
 777         return 0;
 778 }
 779
 780 bool tty_is_vc_resolve(const char *tty) {
 781         _cleanup_free_ char *resolved = NULL;
 782
 783         assert(tty);
 784
 785         tty = skip_dev_prefix(tty);
 786
 787         if (streq(tty, "console")) {
 788                 if (resolve_dev_console(&resolved) < 0)
 789                         return false;
 790
 791                 tty = resolved;
 792         }
 793
 794         return tty_is_vc(tty);
 795 }
 796
 797 const char *default_term_for_tty(const char *tty) {
 798         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 799 }
 800
 801 int fd_columns(int fd) {
 802         struct winsize ws = {};
 803
 804         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 805                 return -errno;
 806
 807         if (ws.ws_col <= 0)
 808                 return -EIO;
 809
 810         return ws.ws_col;
 811 }
 812
 813 unsigned columns(void) {
 814         const char *e;
 815         int c;
 816
 817         if (cached_columns > 0)
 818                 return cached_columns;
 819
 820         c = 0;
 821         e = getenv("COLUMNS");
 822         if (e)
 823                 (void) safe_atoi(e, &c);
 824
 825         if (c <= 0)
 826                 c = fd_columns(STDOUT_FILENO);
 827
 828         if (c <= 0)
 829                 c = 80;
 830
 831         cached_columns = c;
 832         return cached_columns;
 833 }
 834
 835 int fd_lines(int fd) {
 836         struct winsize ws = {};
 837
 838         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 839                 return -errno;
 840
 841         if (ws.ws_row <= 0)
 842                 return -EIO;
 843
 844         return ws.ws_row;
 845 }
 846
 847 unsigned lines(void) {
 848         const char *e;
 849         int l;
 850
 851         if (cached_lines > 0)
 852                 return cached_lines;
 853
 854         l = 0;
 855         e = getenv("LINES");
 856         if (e)
 857                 (void) safe_atoi(e, &l);
 858
 859         if (l <= 0)
 860                 l = fd_lines(STDOUT_FILENO);
 861
 862         if (l <= 0)
 863                 l = 24;
 864
 865         cached_lines = l;
 866         return cached_lines;
 867 }
 868
 869 /* intended to be used as a SIGWINCH sighandler */
 870 void columns_lines_cache_reset(int signum) {
 871         cached_columns = 0;
 872         cached_lines = 0;
 873 }
 874
 875 void reset_terminal_feature_caches(void) {
 876         cached_columns = 0;
 877         cached_lines = 0;
 878
 879         cached_colors_enabled = -1;
 880         cached_underline_enabled = -1;
 881         cached_on_tty = -1;
 882 }
 883
 884 bool on_tty(void) {
 885
 886         /* We check both stdout and stderr, so that situations where pipes on the shell are used are reliably
 887          * recognized, regardless if only the output or the errors are piped to some place. Since on_tty() is generally
 888          * used to default to a safer, non-interactive, non-color mode of operation it's probably good to be defensive
 889          * here, and check for both. Note that we don't check for STDIN_FILENO, because it should fine to use fancy
 890          * terminal functionality when outputting stuff, even if the input is piped to us. */
 891
 892         if (cached_on_tty < 0)
 893                 cached_on_tty =
 894                         isatty(STDOUT_FILENO) > 0 &&
 895                         isatty(STDERR_FILENO) > 0;
 896
 897         return cached_on_tty;
 898 }
 899
 900 int getttyname_malloc(int fd, char **ret) {
 901         size_t l = 100;
 902         int r;
 903
 904         assert(fd >= 0);
 905         assert(ret);
 906
 907         for (;;) {
 908                 char path[l];
 909
 910                 r = ttyname_r(fd, path, sizeof(path));
 911                 if (r == 0) {
 912                         char *c;
 913
 914                         c = strdup(skip_dev_prefix(path));
 915                         if (!c)
 916                                 return -ENOMEM;
 917
 918                         *ret = c;
 919                         return 0;
 920                 }
 921
 922                 if (r != ERANGE)
 923                         return -r;
 924
 925                 l *= 2;
 926         }
 927
 928         return 0;
 929 }
 930
 931 int getttyname_harder(int fd, char **r) {
 932         int k;
 933         char *s = NULL;
 934
 935         k = getttyname_malloc(fd, &s);
 936         if (k < 0)
 937                 return k;
 938
 939         if (streq(s, "tty")) {
 940                 free(s);
 941                 return get_ctty(0, NULL, r);
 942         }
 943
 944         *r = s;
 945         return 0;
 946 }
 947
 948 int get_ctty_devnr(pid_t pid, dev_t *d) {
 949         int r;
 950         _cleanup_free_ char *line = NULL;
 951         const char *p;
 952         unsigned long ttynr;
 953
 954         assert(pid >= 0);
 955
 956         p = procfs_file_alloca(pid, "stat");
 957         r = read_one_line_file(p, &line);
 958         if (r < 0)
 959                 return r;
 960
 961         p = strrchr(line, ')');
 962         if (!p)
 963                 return -EIO;
 964
 965         p++;
 966
 967         if (sscanf(p, " "
 968                    "%*c "  /* state */
 969                    "%*d "  /* ppid */
 970                    "%*d "  /* pgrp */
 971                    "%*d "  /* session */
 972                    "%lu ", /* ttynr */
 973                    &ttynr) != 1)
 974                 return -EIO;
 975
 976         if (major(ttynr) == 0 && minor(ttynr) == 0)
 977                 return -ENXIO;
 978
 979         if (d)
 980                 *d = (dev_t) ttynr;
 981
 982         return 0;
 983 }
 984
 985 int get_ctty(pid_t pid, dev_t *_devnr, char **r) {
 986         char fn[STRLEN("/dev/char/") + 2*DECIMAL_STR_MAX(unsigned) + 1 + 1], *b = NULL;
 987         _cleanup_free_ char *s = NULL;
 988         const char *p;
 989         dev_t devnr;
 990         int k;
 991
 992         assert(r);
 993
 994         k = get_ctty_devnr(pid, &devnr);
 995         if (k < 0)
 996                 return k;
 997
 998         sprintf(fn, "/dev/char/%u:%u", major(devnr), minor(devnr));
 999
1000         k = readlink_malloc(fn, &s);
1001         if (k < 0) {
1002
1003                 if (k != -ENOENT)
1004                         return k;
1005
1006                 /* This is an ugly hack */
1007                 if (major(devnr) == 136) {
1008                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
1009                                 return -ENOMEM;
1010                 } else {
1011                         /* Probably something like the ptys which have no
1012                          * symlink in /dev/char. Let's return something
1013                          * vaguely useful. */
1014
1015                         b = strdup(fn + 5);
1016                         if (!b)
1017                                 return -ENOMEM;
1018                 }
1019         } else {
1020                 if (startswith(s, "/dev/"))
1021                         p = s + 5;
1022                 else if (startswith(s, "../"))
1023                         p = s + 3;
1024                 else
1025                         p = s;
1026
1027                 b = strdup(p);
1028                 if (!b)
1029                         return -ENOMEM;
1030         }
1031
1032         *r = b;
1033         if (_devnr)
1034                 *_devnr = devnr;
1035
1036         return 0;
1037 }
1038
1039 int ptsname_malloc(int fd, char **ret) {
1040         size_t l = 100;
1041
1042         assert(fd >= 0);
1043         assert(ret);
1044
1045         for (;;) {
1046                 char *c;
1047
1048                 c = new(char, l);
1049                 if (!c)
1050                         return -ENOMEM;
1051
1052                 if (ptsname_r(fd, c, l) == 0) {
1053                         *ret = c;
1054                         return 0;
1055                 }
1056                 if (errno != ERANGE) {
1057                         free(c);
1058                         return -errno;
1059                 }
1060
1061                 free(c);
1062                 l *= 2;
1063         }
1064 }
1065
1066 int ptsname_namespace(int pty, char **ret) {
1067         int no = -1, r;
1068
1069         /* Like ptsname(), but doesn't assume that the path is
1070          * accessible in the local namespace. */
1071
1072         r = ioctl(pty, TIOCGPTN, &no);
1073         if (r < 0)
1074                 return -errno;
1075
1076         if (no < 0)
1077                 return -EIO;
1078
1079         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1080                 return -ENOMEM;
1081
1082         return 0;
1083 }
1084
1085 int openpt_in_namespace(pid_t pid, int flags) {
1086         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1087         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1088         pid_t child;
1089         int r;
1090
1091         assert(pid > 0);
1092
1093         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1094         if (r < 0)
1095                 return r;
1096
1097         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1098                 return -errno;
1099
1100         r = safe_fork("(sd-openpt)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &child);
1101         if (r < 0)
1102                 return r;
1103         if (r == 0) {
1104                 int master;
1105
1106                 pair[0] = safe_close(pair[0]);
1107
1108                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
1109                 if (r < 0)
1110                         _exit(EXIT_FAILURE);
1111
1112                 master = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1113                 if (master < 0)
1114                         _exit(EXIT_FAILURE);
1115
1116                 if (unlockpt(master) < 0)
1117                         _exit(EXIT_FAILURE);
1118
1119                 if (send_one_fd(pair[1], master, 0) < 0)
1120                         _exit(EXIT_FAILURE);
1121
1122                 _exit(EXIT_SUCCESS);
1123         }
1124
1125         pair[1] = safe_close(pair[1]);
1126
1127         r = wait_for_terminate_and_check("(sd-openpt)", child, 0);
1128         if (r < 0)
1129                 return r;
1130         if (r != EXIT_SUCCESS)
1131                 return -EIO;
1132
1133         return receive_one_fd(pair[0], 0);
1134 }
1135
1136 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1137         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1138         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1139         pid_t child;
1140         int r;
1141
1142         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1143         if (r < 0)
1144                 return r;
1145
1146         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1147                 return -errno;
1148
1149         r = safe_fork("(sd-terminal)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &child);
1150         if (r < 0)
1151                 return r;
1152         if (r == 0) {
1153                 int master;
1154
1155                 pair[0] = safe_close(pair[0]);
1156
1157                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
1158                 if (r < 0)
1159                         _exit(EXIT_FAILURE);
1160
1161                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1162                 if (master < 0)
1163                         _exit(EXIT_FAILURE);
1164
1165                 if (send_one_fd(pair[1], master, 0) < 0)
1166                         _exit(EXIT_FAILURE);
1167
1168                 _exit(EXIT_SUCCESS);
1169         }
1170
1171         pair[1] = safe_close(pair[1]);
1172
1173         r = wait_for_terminate_and_check("(sd-terminal)", child, 0);
1174         if (r < 0)
1175                 return r;
1176         if (r != EXIT_SUCCESS)
1177                 return -EIO;
1178
1179         return receive_one_fd(pair[0], 0);
1180 }
1181
1182 static bool getenv_terminal_is_dumb(void) {
1183         const char *e;
1184
1185         e = getenv("TERM");
1186         if (!e)
1187                 return true;
1188
1189         return streq(e, "dumb");
1190 }
1191
1192 bool terminal_is_dumb(void) {
1193         if (!on_tty())
1194                 return true;
1195
1196         return getenv_terminal_is_dumb();
1197 }
1198
1199 bool colors_enabled(void) {
1200
1201         /* Returns true if colors are considered supported on our stdout. For that we check $SYSTEMD_COLORS first
1202          * (which is the explicit way to turn colors on/off). If that didn't work we turn colors off unless we are on a
1203          * TTY. And if we are on a TTY we turn it off if $TERM is set to "dumb". There's one special tweak though: if
1204          * we are PID 1 then we do not check whether we are connected to a TTY, because we don't keep /dev/console open
1205          * continously due to fear of SAK, and hence things are a bit weird. */
1206
1207         if (cached_colors_enabled < 0) {
1208                 int val;
1209
1210                 val = getenv_bool("SYSTEMD_COLORS");
1211                 if (val >= 0)
1212                         cached_colors_enabled = val;
1213                 else if (getpid_cached() == 1)
1214                         /* PID1 outputs to the console without holding it open all the time */
1215                         cached_colors_enabled = !getenv_terminal_is_dumb();
1216                 else
1217                         cached_colors_enabled = !terminal_is_dumb();
1218         }
1219
1220         return cached_colors_enabled;
1221 }
1222
1223 bool dev_console_colors_enabled(void) {
1224         _cleanup_free_ char *s = NULL;
1225         int b;
1226
1227         /* Returns true if we assume that color is supported on /dev/console.
1228          *
1229          * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
1230          * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
1231          * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
1232          * colors_enabled() operates. */
1233
1234         b = getenv_bool("SYSTEMD_COLORS");
1235         if (b >= 0)
1236                 return b;
1237
1238         if (getenv_for_pid(1, "TERM", &s) <= 0)
1239                 (void) proc_cmdline_get_key("TERM", 0, &s);
1240
1241         return !streq_ptr(s, "dumb");
1242 }
1243
1244 bool underline_enabled(void) {
1245
1246         if (cached_underline_enabled < 0) {
1247
1248                 /* The Linux console doesn't support underlining, turn it off, but only there. */
1249
1250                 if (colors_enabled())
1251                         cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
1252                 else
1253                         cached_underline_enabled = false;
1254         }
1255
1256         return cached_underline_enabled;
1257 }
1258
1259 int vt_default_utf8(void) {
1260         _cleanup_free_ char *b = NULL;
1261         int r;
1262
1263         /* Read the default VT UTF8 setting from the kernel */
1264
1265         r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
1266         if (r < 0)
1267                 return r;
1268
1269         return parse_boolean(b);
1270 }
1271
1272 int vt_reset_keyboard(int fd) {
1273         int kb;
1274
1275         /* If we can't read the default, then default to unicode. It's 2017 after all. */
1276         kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
1277
1278         if (ioctl(fd, KDSKBMODE, kb) < 0)
1279                 return -errno;
1280
1281         return 0;
1282 }
1283
1284 static bool urlify_enabled(void) {
1285         static int cached_urlify_enabled = -1;
1286
1287         /* Unfortunately 'less' doesn't support links like this yet 😭, hence let's disable this as long as there's a
1288          * pager in effect. Let's drop this check as soon as less got fixed a and enough time passed so that it's safe
1289          * to assume that a link-enabled 'less' version has hit most installations. */
1290
1291         if (cached_urlify_enabled < 0) {
1292                 int val;
1293
1294                 val = getenv_bool("SYSTEMD_URLIFY");
1295                 if (val >= 0)
1296                         cached_urlify_enabled = val;
1297                 else
1298                         cached_urlify_enabled = colors_enabled() && !pager_have();
1299         }
1300
1301         return cached_urlify_enabled;
1302 }
1303
1304 int terminal_urlify(const char *url, const char *text, char **ret) {
1305         char *n;
1306
1307         assert(url);
1308
1309         /* Takes an URL and a pretty string and formats it as clickable link for the terminal. See
1310          * https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda for details. */
1311
1312         if (isempty(text))
1313                 text = url;
1314
1315         if (urlify_enabled())
1316                 n = strjoin("\x1B]8;;", url, "\a", text, "\x1B]8;;\a");
1317         else
1318                 n = strdup(text);
1319         if (!n)
1320                 return -ENOMEM;
1321
1322         *ret = n;
1323         return 0;
1324 }
1325
1326 int terminal_urlify_path(const char *path, const char *text, char **ret) {
1327         _cleanup_free_ char *absolute = NULL;
1328         struct utsname u;
1329         const char *url;
1330         int r;
1331
1332         assert(path);
1333
1334         /* Much like terminal_urlify() above, but takes a file system path as input
1335          * and turns it into a proper file:// URL first. */
1336
1337         if (isempty(path))
1338                 return -EINVAL;
1339
1340         if (isempty(text))
1341                 text = path;
1342
1343         if (!urlify_enabled()) {
1344                 char *n;
1345
1346                 n = strdup(text);
1347                 if (!n)
1348                         return -ENOMEM;
1349
1350                 *ret = n;
1351                 return 0;
1352         }
1353
1354         if (uname(&u) < 0)
1355                 return -errno;
1356
1357         if (!path_is_absolute(path)) {
1358                 r = path_make_absolute_cwd(path, &absolute);
1359                 if (r < 0)
1360                         return r;
1361
1362                 path = absolute;
1363         }
1364
1365         /* As suggested by https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda, let's include the local
1366          * hostname here. Note that we don't use gethostname_malloc() or gethostname_strict() since we are interested
1367          * in the raw string the kernel has set, whatever it may be, under the assumption that terminals are not overly
1368          * careful with validating the strings either. */
1369
1370         url = strjoina("file://", u.nodename, path);
1371
1372         return terminal_urlify(url, text, ret);
1373 }
1374
1375 static int cat_file(const char *filename, bool newline) {
1376         _cleanup_fclose_ FILE *f = NULL;
1377         _cleanup_free_ char *urlified = NULL;
1378         int r;
1379
1380         f = fopen(filename, "re");
1381         if (!f)
1382                 return -errno;
1383
1384         r = terminal_urlify_path(filename, NULL, &urlified);
1385         if (r < 0)
1386                 return r;
1387
1388         printf("%s%s# %s%s\n",
1389                newline ? "\n" : "",
1390                ansi_highlight_blue(),
1391                urlified,
1392                ansi_normal());
1393         fflush(stdout);
1394
1395         for (;;) {
1396                 _cleanup_free_ char *line = NULL;
1397
1398                 r = read_line(f, LONG_LINE_MAX, &line);
1399                 if (r < 0)
1400                         return log_error_errno(r, "Failed to read \"%s\": %m", filename);
1401                 if (r == 0)
1402                         break;
1403
1404                 puts(line);
1405         }
1406
1407         return 0;
1408 }
1409
1410 int cat_files(const char *file, char **dropins, CatFlags flags) {
1411         char **path;
1412         int r;
1413
1414         if (file) {
1415                 r = cat_file(file, false);
1416                 if (r == -ENOENT && (flags & CAT_FLAGS_MAIN_FILE_OPTIONAL))
1417                         printf("%s# config file %s not found%s\n",
1418                                ansi_highlight_magenta(),
1419                                file,
1420                                ansi_normal());
1421                 else if (r < 0)
1422                         return log_warning_errno(r, "Failed to cat %s: %m", file);
1423         }
1424
1425         STRV_FOREACH(path, dropins) {
1426                 r = cat_file(*path, file || path != dropins);
1427                 if (r < 0)
1428                         return log_warning_errno(r, "Failed to cat %s: %m", *path);
1429         }
1430
1431         return 0;
1432 }
1433
1434 void print_separator(void) {
1435
1436         /* Outputs a separator line that resolves to whitespace when copied from the terminal. We do that by outputting
1437          * one line filled with spaces with ANSI underline set, followed by a second (empty) line. */
1438
1439         if (underline_enabled()) {
1440                 size_t i, c;
1441
1442                 c = columns();
1443
1444                 flockfile(stdout);
1445                 fputs_unlocked(ANSI_UNDERLINE, stdout);
1446
1447                 for (i = 0; i < c; i++)
1448                         fputc_unlocked(' ', stdout);
1449
1450                 fputs_unlocked(ANSI_NORMAL "\n\n", stdout);
1451                 funlockfile(stdout);
1452         } else
1453                 fputs("\n\n", stdout);
1454 }