src/basic/terminal-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <limits.h>
   6 #include <linux/kd.h>
   7 #include <linux/tiocl.h>
   8 #include <linux/vt.h>
   9 #include <poll.h>
  10 #include <signal.h>
  11 #include <stdarg.h>
  12 #include <stddef.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include <sys/inotify.h>
  16 #include <sys/ioctl.h>
  17 #include <sys/socket.h>
  18 #include <sys/sysmacros.h>
  19 #include <sys/time.h>
  20 #include <sys/types.h>
  21 #include <sys/utsname.h>
  22 #include <termios.h>
  23 #include <unistd.h>
  24
  25 #include "alloc-util.h"
  26 #include "copy.h"
  27 #include "def.h"
  28 #include "env-util.h"
  29 #include "fd-util.h"
  30 #include "fileio.h"
  31 #include "fs-util.h"
  32 #include "io-util.h"
  33 #include "log.h"
  34 #include "macro.h"
  35 #include "namespace-util.h"
  36 #include "parse-util.h"
  37 #include "path-util.h"
  38 #include "proc-cmdline.h"
  39 #include "process-util.h"
  40 #include "socket-util.h"
  41 #include "stat-util.h"
  42 #include "string-util.h"
  43 #include "strv.h"
  44 #include "terminal-util.h"
  45 #include "time-util.h"
  46 #include "util.h"
  47
  48 static volatile unsigned cached_columns = 0;
  49 static volatile unsigned cached_lines = 0;
  50
  51 static volatile int cached_on_tty = -1;
  52 static volatile int cached_colors_enabled = -1;
  53 static volatile int cached_underline_enabled = -1;
  54
  55 int chvt(int vt) {
  56         _cleanup_close_ int fd;
  57
  58         /* Switch to the specified vt number. If the VT is specified <= 0 switch to the VT the kernel log messages go,
  59          * if that's configured. */
  60
  61         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
  62         if (fd < 0)
  63                 return -errno;
  64
  65         if (vt <= 0) {
  66                 int tiocl[2] = {
  67                         TIOCL_GETKMSGREDIRECT,
  68                         0
  69                 };
  70
  71                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  72                         return -errno;
  73
  74                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  75         }
  76
  77         if (ioctl(fd, VT_ACTIVATE, vt) < 0)
  78                 return -errno;
  79
  80         return 0;
  81 }
  82
  83 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  84         _cleanup_free_ char *line = NULL;
  85         struct termios old_termios;
  86         int r;
  87
  88         assert(f);
  89         assert(ret);
  90
  91         /* If this is a terminal, then switch canonical mode off, so that we can read a single character */
  92         if (tcgetattr(fileno(f), &old_termios) >= 0) {
  93                 struct termios new_termios = old_termios;
  94
  95                 new_termios.c_lflag &= ~ICANON;
  96                 new_termios.c_cc[VMIN] = 1;
  97                 new_termios.c_cc[VTIME] = 0;
  98
  99                 if (tcsetattr(fileno(f), TCSADRAIN, &new_termios) >= 0) {
 100                         char c;
 101
 102                         if (t != USEC_INFINITY) {
 103                                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0) {
 104                                         (void) tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 105                                         return -ETIMEDOUT;
 106                                 }
 107                         }
 108
 109                         r = safe_fgetc(f, &c);
 110                         (void) tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 111                         if (r < 0)
 112                                 return r;
 113                         if (r == 0)
 114                                 return -EIO;
 115
 116                         if (need_nl)
 117                                 *need_nl = c != '\n';
 118
 119                         *ret = c;
 120                         return 0;
 121                 }
 122         }
 123
 124         if (t != USEC_INFINITY) {
 125                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
 126                         return -ETIMEDOUT;
 127         }
 128
 129         /* If this is not a terminal, then read a full line instead */
 130
 131         r = read_line(f, 16, &line); /* longer than necessary, to eat up UTF-8 chars/vt100 key sequences */
 132         if (r < 0)
 133                 return r;
 134         if (r == 0)
 135                 return -EIO;
 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 #define DEFAULT_ASK_REFRESH_USEC (2*USEC_PER_SEC)
 148
 149 int ask_char(char *ret, const char *replies, const char *fmt, ...) {
 150         int r;
 151
 152         assert(ret);
 153         assert(replies);
 154         assert(fmt);
 155
 156         for (;;) {
 157                 va_list ap;
 158                 char c;
 159                 bool need_nl = true;
 160
 161                 if (colors_enabled())
 162                         fputs(ANSI_HIGHLIGHT, stdout);
 163
 164                 putchar('\r');
 165
 166                 va_start(ap, fmt);
 167                 vprintf(fmt, ap);
 168                 va_end(ap);
 169
 170                 if (colors_enabled())
 171                         fputs(ANSI_NORMAL, stdout);
 172
 173                 fflush(stdout);
 174
 175                 r = read_one_char(stdin, &c, DEFAULT_ASK_REFRESH_USEC, &need_nl);
 176                 if (r < 0) {
 177
 178                         if (r == -ETIMEDOUT)
 179                                 continue;
 180
 181                         if (r == -EBADMSG) {
 182                                 puts("Bad input, please try again.");
 183                                 continue;
 184                         }
 185
 186                         putchar('\n');
 187                         return r;
 188                 }
 189
 190                 if (need_nl)
 191                         putchar('\n');
 192
 193                 if (strchr(replies, c)) {
 194                         *ret = c;
 195                         return 0;
 196                 }
 197
 198                 puts("Read unexpected character, please try again.");
 199         }
 200 }
 201
 202 int ask_string(char **ret, const char *text, ...) {
 203         _cleanup_free_ char *line = NULL;
 204         va_list ap;
 205         int r;
 206
 207         assert(ret);
 208         assert(text);
 209
 210         if (colors_enabled())
 211                 fputs(ANSI_HIGHLIGHT, stdout);
 212
 213         va_start(ap, text);
 214         vprintf(text, ap);
 215         va_end(ap);
 216
 217         if (colors_enabled())
 218                 fputs(ANSI_NORMAL, stdout);
 219
 220         fflush(stdout);
 221
 222         r = read_line(stdin, LONG_LINE_MAX, &line);
 223         if (r < 0)
 224                 return r;
 225         if (r == 0)
 226                 return -EIO;
 227
 228         *ret = TAKE_PTR(line);
 229         return 0;
 230 }
 231
 232 int reset_terminal_fd(int fd, bool switch_to_text) {
 233         struct termios termios;
 234         int r = 0;
 235
 236         /* Set terminal to some sane defaults */
 237
 238         assert(fd >= 0);
 239
 240         /* We leave locked terminal attributes untouched, so that
 241          * Plymouth may set whatever it wants to set, and we don't
 242          * interfere with that. */
 243
 244         /* Disable exclusive mode, just in case */
 245         (void) ioctl(fd, TIOCNXCL);
 246
 247         /* Switch to text mode */
 248         if (switch_to_text)
 249                 (void) ioctl(fd, KDSETMODE, KD_TEXT);
 250
 251         /* Set default keyboard mode */
 252         (void) vt_reset_keyboard(fd);
 253
 254         if (tcgetattr(fd, &termios) < 0) {
 255                 r = -errno;
 256                 goto finish;
 257         }
 258
 259         /* We only reset the stuff that matters to the software. How
 260          * hardware is set up we don't touch assuming that somebody
 261          * else will do that for us */
 262
 263         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 264         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 265         termios.c_oflag |= ONLCR;
 266         termios.c_cflag |= CREAD;
 267         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 268
 269         termios.c_cc[VINTR]    =   03;  /* ^C */
 270         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 271         termios.c_cc[VERASE]   = 0177;
 272         termios.c_cc[VKILL]    =  025;  /* ^X */
 273         termios.c_cc[VEOF]     =   04;  /* ^D */
 274         termios.c_cc[VSTART]   =  021;  /* ^Q */
 275         termios.c_cc[VSTOP]    =  023;  /* ^S */
 276         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 277         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 278         termios.c_cc[VWERASE]  =  027;  /* ^W */
 279         termios.c_cc[VREPRINT] =  022;  /* ^R */
 280         termios.c_cc[VEOL]     =    0;
 281         termios.c_cc[VEOL2]    =    0;
 282
 283         termios.c_cc[VTIME]  = 0;
 284         termios.c_cc[VMIN]   = 1;
 285
 286         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 287                 r = -errno;
 288
 289 finish:
 290         /* Just in case, flush all crap out */
 291         (void) tcflush(fd, TCIOFLUSH);
 292
 293         return r;
 294 }
 295
 296 int reset_terminal(const char *name) {
 297         _cleanup_close_ int fd = -1;
 298
 299         /* We open the terminal with O_NONBLOCK here, to ensure we
 300          * don't block on carrier if this is a terminal with carrier
 301          * configured. */
 302
 303         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 304         if (fd < 0)
 305                 return fd;
 306
 307         return reset_terminal_fd(fd, true);
 308 }
 309
 310 int open_terminal(const char *name, int mode) {
 311         unsigned c = 0;
 312         int fd;
 313
 314         /*
 315          * If a TTY is in the process of being closed opening it might
 316          * cause EIO. This is horribly awful, but unlikely to be
 317          * changed in the kernel. Hence we work around this problem by
 318          * retrying a couple of times.
 319          *
 320          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 321          */
 322
 323         if (mode & O_CREAT)
 324                 return -EINVAL;
 325
 326         for (;;) {
 327                 fd = open(name, mode, 0);
 328                 if (fd >= 0)
 329                         break;
 330
 331                 if (errno != EIO)
 332                         return -errno;
 333
 334                 /* Max 1s in total */
 335                 if (c >= 20)
 336                         return -errno;
 337
 338                 usleep(50 * USEC_PER_MSEC);
 339                 c++;
 340         }
 341
 342         if (isatty(fd) <= 0) {
 343                 safe_close(fd);
 344                 return -ENOTTY;
 345         }
 346
 347         return fd;
 348 }
 349
 350 int acquire_terminal(
 351                 const char *name,
 352                 AcquireTerminalFlags flags,
 353                 usec_t timeout) {
 354
 355         _cleanup_close_ int notify = -1, fd = -1;
 356         usec_t ts = USEC_INFINITY;
 357         int r, wd = -1;
 358
 359         assert(name);
 360         assert(IN_SET(flags & ~ACQUIRE_TERMINAL_PERMISSIVE, ACQUIRE_TERMINAL_TRY, ACQUIRE_TERMINAL_FORCE, ACQUIRE_TERMINAL_WAIT));
 361
 362         /* We use inotify to be notified when the tty is closed. We create the watch before checking if we can actually
 363          * acquire it, so that we don't lose any event.
 364          *
 365          * Note: strictly speaking this actually watches for the device being closed, it does *not* really watch
 366          * whether a tty loses its controlling process. However, unless some rogue process uses TIOCNOTTY on /dev/tty
 367          * *after* closing its tty otherwise this will not become a problem. As long as the administrator makes sure to
 368          * not configure any service on the same tty as an untrusted user this should not be a problem. (Which they
 369          * probably should not do anyway.) */
 370
 371         if ((flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_WAIT) {
 372                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 373                 if (notify < 0)
 374                         return -errno;
 375
 376                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 377                 if (wd < 0)
 378                         return -errno;
 379
 380                 if (timeout != USEC_INFINITY)
 381                         ts = now(CLOCK_MONOTONIC);
 382         }
 383
 384         for (;;) {
 385                 struct sigaction sa_old, sa_new = {
 386                         .sa_handler = SIG_IGN,
 387                         .sa_flags = SA_RESTART,
 388                 };
 389
 390                 if (notify >= 0) {
 391                         r = flush_fd(notify);
 392                         if (r < 0)
 393                                 return r;
 394                 }
 395
 396                 /* We pass here O_NOCTTY only so that we can check the return value TIOCSCTTY and have a reliable way
 397                  * to figure out if we successfully became the controlling process of the tty */
 398                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 399                 if (fd < 0)
 400                         return fd;
 401
 402                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed if we already own the tty. */
 403                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 404
 405                 /* First, try to get the tty */
 406                 r = ioctl(fd, TIOCSCTTY,
 407                           (flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_FORCE) < 0 ? -errno : 0;
 408
 409                 /* Reset signal handler to old value */
 410                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 411
 412                 /* Success? Exit the loop now! */
 413                 if (r >= 0)
 414                         break;
 415
 416                 /* Any failure besides -EPERM? Fail, regardless of the mode. */
 417                 if (r != -EPERM)
 418                         return r;
 419
 420                 if (flags & ACQUIRE_TERMINAL_PERMISSIVE) /* If we are in permissive mode, then EPERM is fine, turn this
 421                                                           * into a success. Note that EPERM is also returned if we
 422                                                           * already are the owner of the TTY. */
 423                         break;
 424
 425                 if (flags != ACQUIRE_TERMINAL_WAIT) /* If we are in TRY or FORCE mode, then propagate EPERM as EPERM */
 426                         return r;
 427
 428                 assert(notify >= 0);
 429                 assert(wd >= 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                                 assert(ts != USEC_INFINITY);
 440
 441                                 n = now(CLOCK_MONOTONIC);
 442                                 if (ts + timeout < n)
 443                                         return -ETIMEDOUT;
 444
 445                                 r = fd_wait_for_event(notify, POLLIN, ts + timeout - n);
 446                                 if (r < 0)
 447                                         return r;
 448                                 if (r == 0)
 449                                         return -ETIMEDOUT;
 450                         }
 451
 452                         l = read(notify, &buffer, sizeof(buffer));
 453                         if (l < 0) {
 454                                 if (IN_SET(errno, EINTR, EAGAIN))
 455                                         continue;
 456
 457                                 return -errno;
 458                         }
 459
 460                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 461                                 if (e->mask & IN_Q_OVERFLOW) /* If we hit an inotify queue overflow, simply check if the terminal is up for grabs now. */
 462                                         break;
 463
 464                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) /* Safety checks */
 465                                         return -EIO;
 466                         }
 467
 468                         break;
 469                 }
 470
 471                 /* We close the tty fd here since if the old session ended our handle will be dead. It's important that
 472                  * we do this after sleeping, so that we don't enter an endless loop. */
 473                 fd = safe_close(fd);
 474         }
 475
 476         return TAKE_FD(fd);
 477 }
 478
 479 int release_terminal(void) {
 480         static const struct sigaction sa_new = {
 481                 .sa_handler = SIG_IGN,
 482                 .sa_flags = SA_RESTART,
 483         };
 484
 485         _cleanup_close_ int fd = -1;
 486         struct sigaction sa_old;
 487         int r;
 488
 489         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 490         if (fd < 0)
 491                 return -errno;
 492
 493         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 494          * by our own TIOCNOTTY */
 495         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 496
 497         r = ioctl(fd, TIOCNOTTY) < 0 ? -errno : 0;
 498
 499         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 500
 501         return r;
 502 }
 503
 504 int terminal_vhangup_fd(int fd) {
 505         assert(fd >= 0);
 506
 507         if (ioctl(fd, TIOCVHANGUP) < 0)
 508                 return -errno;
 509
 510         return 0;
 511 }
 512
 513 int terminal_vhangup(const char *name) {
 514         _cleanup_close_ int fd;
 515
 516         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 517         if (fd < 0)
 518                 return fd;
 519
 520         return terminal_vhangup_fd(fd);
 521 }
 522
 523 int vt_disallocate(const char *name) {
 524         const char *e;
 525         int r;
 526
 527         /* Deallocate the VT if possible. If not possible
 528          * (i.e. because it is the active one), at least clear it
 529          * entirely (including the scrollback buffer). */
 530
 531         e = path_startswith(name, "/dev/");
 532         if (!e)
 533                 return -EINVAL;
 534
 535         if (tty_is_vc(name)) {
 536                 _cleanup_close_ int fd = -1;
 537                 unsigned u;
 538                 const char *n;
 539
 540                 n = startswith(e, "tty");
 541                 if (!n)
 542                         return -EINVAL;
 543
 544                 r = safe_atou(n, &u);
 545                 if (r < 0)
 546                         return r;
 547
 548                 if (u <= 0)
 549                         return -EINVAL;
 550
 551                 /* Try to deallocate */
 552                 fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 553                 if (fd < 0)
 554                         return fd;
 555
 556                 r = ioctl(fd, VT_DISALLOCATE, u);
 557                 if (r >= 0)
 558                         return 0;
 559                 if (errno != EBUSY)
 560                         return -errno;
 561         }
 562
 563         /* So this is not a VT (in which case we cannot deallocate it),
 564          * or we failed to deallocate. Let's at least clear the screen. */
 565
 566         _cleanup_close_ int fd2 = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 567         if (fd2 < 0)
 568                 return fd2;
 569
 570         (void) loop_write(fd2,
 571                           "\033[r"   /* clear scrolling region */
 572                           "\033[H"   /* move home */
 573                           "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 574                           10, false);
 575         return 0;
 576 }
 577
 578 int make_console_stdio(void) {
 579         int fd, r;
 580
 581         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 582
 583         fd = acquire_terminal("/dev/console", ACQUIRE_TERMINAL_FORCE|ACQUIRE_TERMINAL_PERMISSIVE, USEC_INFINITY);
 584         if (fd < 0)
 585                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 586
 587         r = reset_terminal_fd(fd, true);
 588         if (r < 0)
 589                 log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 590
 591         r = rearrange_stdio(fd, fd, fd); /* This invalidates 'fd' both on success and on failure. */
 592         if (r < 0)
 593                 return log_error_errno(r, "Failed to make terminal stdin/stdout/stderr: %m");
 594
 595         reset_terminal_feature_caches();
 596
 597         return 0;
 598 }
 599
 600 bool tty_is_vc(const char *tty) {
 601         assert(tty);
 602
 603         return vtnr_from_tty(tty) >= 0;
 604 }
 605
 606 bool tty_is_console(const char *tty) {
 607         assert(tty);
 608
 609         return streq(skip_dev_prefix(tty), "console");
 610 }
 611
 612 int vtnr_from_tty(const char *tty) {
 613         int i, r;
 614
 615         assert(tty);
 616
 617         tty = skip_dev_prefix(tty);
 618
 619         if (!startswith(tty, "tty") )
 620                 return -EINVAL;
 621
 622         if (tty[3] < '0' || tty[3] > '9')
 623                 return -EINVAL;
 624
 625         r = safe_atoi(tty+3, &i);
 626         if (r < 0)
 627                 return r;
 628
 629         if (i < 0 || i > 63)
 630                 return -EINVAL;
 631
 632         return i;
 633 }
 634
 635  int resolve_dev_console(char **ret) {
 636         _cleanup_free_ char *active = NULL;
 637         char *tty;
 638         int r;
 639
 640         assert(ret);
 641
 642         /* Resolve where /dev/console is pointing to, if /sys is actually ours (i.e. not read-only-mounted which is a
 643          * sign for container setups) */
 644
 645         if (path_is_read_only_fs("/sys") > 0)
 646                 return -ENOMEDIUM;
 647
 648         r = read_one_line_file("/sys/class/tty/console/active", &active);
 649         if (r < 0)
 650                 return r;
 651
 652         /* If multiple log outputs are configured the last one is what /dev/console points to */
 653         tty = strrchr(active, ' ');
 654         if (tty)
 655                 tty++;
 656         else
 657                 tty = active;
 658
 659         if (streq(tty, "tty0")) {
 660                 active = mfree(active);
 661
 662                 /* Get the active VC (e.g. tty1) */
 663                 r = read_one_line_file("/sys/class/tty/tty0/active", &active);
 664                 if (r < 0)
 665                         return r;
 666
 667                 tty = active;
 668         }
 669
 670         if (tty == active)
 671                 *ret = TAKE_PTR(active);
 672         else {
 673                 char *tmp;
 674
 675                 tmp = strdup(tty);
 676                 if (!tmp)
 677                         return -ENOMEM;
 678
 679                 *ret = tmp;
 680         }
 681
 682         return 0;
 683 }
 684
 685 int get_kernel_consoles(char ***ret) {
 686         _cleanup_strv_free_ char **l = NULL;
 687         _cleanup_free_ char *line = NULL;
 688         const char *p;
 689         int r;
 690
 691         assert(ret);
 692
 693         /* If /sys is mounted read-only this means we are running in some kind of container environment. In that
 694          * case /sys would reflect the host system, not us, hence ignore the data we can read from it. */
 695         if (path_is_read_only_fs("/sys") > 0)
 696                 goto fallback;
 697
 698         r = read_one_line_file("/sys/class/tty/console/active", &line);
 699         if (r < 0)
 700                 return r;
 701
 702         p = line;
 703         for (;;) {
 704                 _cleanup_free_ char *tty = NULL, *path = NULL;
 705
 706                 r = extract_first_word(&p, &tty, NULL, 0);
 707                 if (r < 0)
 708                         return r;
 709                 if (r == 0)
 710                         break;
 711
 712                 if (streq(tty, "tty0")) {
 713                         tty = mfree(tty);
 714                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 715                         if (r < 0)
 716                                 return r;
 717                 }
 718
 719                 path = path_join("/dev", tty);
 720                 if (!path)
 721                         return -ENOMEM;
 722
 723                 if (access(path, F_OK) < 0) {
 724                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 725                         continue;
 726                 }
 727
 728                 r = strv_consume(&l, TAKE_PTR(path));
 729                 if (r < 0)
 730                         return r;
 731         }
 732
 733         if (strv_isempty(l)) {
 734                 log_debug("No devices found for system console");
 735                 goto fallback;
 736         }
 737
 738         *ret = TAKE_PTR(l);
 739
 740         return 0;
 741
 742 fallback:
 743         r = strv_extend(&l, "/dev/console");
 744         if (r < 0)
 745                 return r;
 746
 747         *ret = TAKE_PTR(l);
 748
 749         return 0;
 750 }
 751
 752 bool tty_is_vc_resolve(const char *tty) {
 753         _cleanup_free_ char *resolved = NULL;
 754
 755         assert(tty);
 756
 757         tty = skip_dev_prefix(tty);
 758
 759         if (streq(tty, "console")) {
 760                 if (resolve_dev_console(&resolved) < 0)
 761                         return false;
 762
 763                 tty = resolved;
 764         }
 765
 766         return tty_is_vc(tty);
 767 }
 768
 769 const char *default_term_for_tty(const char *tty) {
 770         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 771 }
 772
 773 int fd_columns(int fd) {
 774         struct winsize ws = {};
 775
 776         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 777                 return -errno;
 778
 779         if (ws.ws_col <= 0)
 780                 return -EIO;
 781
 782         return ws.ws_col;
 783 }
 784
 785 unsigned columns(void) {
 786         const char *e;
 787         int c;
 788
 789         if (cached_columns > 0)
 790                 return cached_columns;
 791
 792         c = 0;
 793         e = getenv("COLUMNS");
 794         if (e)
 795                 (void) safe_atoi(e, &c);
 796
 797         if (c <= 0 || c > USHRT_MAX) {
 798                 c = fd_columns(STDOUT_FILENO);
 799                 if (c <= 0)
 800                         c = 80;
 801         }
 802
 803         cached_columns = c;
 804         return cached_columns;
 805 }
 806
 807 int fd_lines(int fd) {
 808         struct winsize ws = {};
 809
 810         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 811                 return -errno;
 812
 813         if (ws.ws_row <= 0)
 814                 return -EIO;
 815
 816         return ws.ws_row;
 817 }
 818
 819 unsigned lines(void) {
 820         const char *e;
 821         int l;
 822
 823         if (cached_lines > 0)
 824                 return cached_lines;
 825
 826         l = 0;
 827         e = getenv("LINES");
 828         if (e)
 829                 (void) safe_atoi(e, &l);
 830
 831         if (l <= 0 || l > USHRT_MAX) {
 832                 l = fd_lines(STDOUT_FILENO);
 833                 if (l <= 0)
 834                         l = 24;
 835         }
 836
 837         cached_lines = l;
 838         return cached_lines;
 839 }
 840
 841 /* intended to be used as a SIGWINCH sighandler */
 842 void columns_lines_cache_reset(int signum) {
 843         cached_columns = 0;
 844         cached_lines = 0;
 845 }
 846
 847 void reset_terminal_feature_caches(void) {
 848         cached_columns = 0;
 849         cached_lines = 0;
 850
 851         cached_colors_enabled = -1;
 852         cached_underline_enabled = -1;
 853         cached_on_tty = -1;
 854 }
 855
 856 bool on_tty(void) {
 857
 858         /* We check both stdout and stderr, so that situations where pipes on the shell are used are reliably
 859          * recognized, regardless if only the output or the errors are piped to some place. Since on_tty() is generally
 860          * used to default to a safer, non-interactive, non-color mode of operation it's probably good to be defensive
 861          * here, and check for both. Note that we don't check for STDIN_FILENO, because it should fine to use fancy
 862          * terminal functionality when outputting stuff, even if the input is piped to us. */
 863
 864         if (cached_on_tty < 0)
 865                 cached_on_tty =
 866                         isatty(STDOUT_FILENO) > 0 &&
 867                         isatty(STDERR_FILENO) > 0;
 868
 869         return cached_on_tty;
 870 }
 871
 872 int getttyname_malloc(int fd, char **ret) {
 873         char path[PATH_MAX], *c; /* PATH_MAX is counted *with* the trailing NUL byte */
 874         int r;
 875
 876         assert(fd >= 0);
 877         assert(ret);
 878
 879         r = ttyname_r(fd, path, sizeof path); /* positive error */
 880         assert(r >= 0);
 881         if (r == ERANGE)
 882                 return -ENAMETOOLONG;
 883         if (r > 0)
 884                 return -r;
 885
 886         c = strdup(skip_dev_prefix(path));
 887         if (!c)
 888                 return -ENOMEM;
 889
 890         *ret = c;
 891         return 0;
 892 }
 893
 894 int getttyname_harder(int fd, char **ret) {
 895         _cleanup_free_ char *s = NULL;
 896         int r;
 897
 898         r = getttyname_malloc(fd, &s);
 899         if (r < 0)
 900                 return r;
 901
 902         if (streq(s, "tty"))
 903                 return get_ctty(0, NULL, ret);
 904
 905         *ret = TAKE_PTR(s);
 906         return 0;
 907 }
 908
 909 int get_ctty_devnr(pid_t pid, dev_t *d) {
 910         int r;
 911         _cleanup_free_ char *line = NULL;
 912         const char *p;
 913         unsigned long ttynr;
 914
 915         assert(pid >= 0);
 916
 917         p = procfs_file_alloca(pid, "stat");
 918         r = read_one_line_file(p, &line);
 919         if (r < 0)
 920                 return r;
 921
 922         p = strrchr(line, ')');
 923         if (!p)
 924                 return -EIO;
 925
 926         p++;
 927
 928         if (sscanf(p, " "
 929                    "%*c "  /* state */
 930                    "%*d "  /* ppid */
 931                    "%*d "  /* pgrp */
 932                    "%*d "  /* session */
 933                    "%lu ", /* ttynr */
 934                    &ttynr) != 1)
 935                 return -EIO;
 936
 937         if (major(ttynr) == 0 && minor(ttynr) == 0)
 938                 return -ENXIO;
 939
 940         if (d)
 941                 *d = (dev_t) ttynr;
 942
 943         return 0;
 944 }
 945
 946 int get_ctty(pid_t pid, dev_t *ret_devnr, char **ret) {
 947         _cleanup_free_ char *fn = NULL, *b = NULL;
 948         dev_t devnr;
 949         int r;
 950
 951         r = get_ctty_devnr(pid, &devnr);
 952         if (r < 0)
 953                 return r;
 954
 955         r = device_path_make_canonical(S_IFCHR, devnr, &fn);
 956         if (r < 0) {
 957                 if (r != -ENOENT) /* No symlink for this in /dev/char/? */
 958                         return r;
 959
 960                 if (major(devnr) == 136) {
 961                         /* This is an ugly hack: PTY devices are not listed in /dev/char/, as they don't follow the
 962                          * Linux device model. This means we have no nice way to match them up against their actual
 963                          * device node. Let's hence do the check by the fixed, assigned major number. Normally we try
 964                          * to avoid such fixed major/minor matches, but there appears to nother nice way to handle
 965                          * this. */
 966
 967                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
 968                                 return -ENOMEM;
 969                 } else {
 970                         /* Probably something similar to the ptys which have no symlink in /dev/char/. Let's return
 971                          * something vaguely useful. */
 972
 973                         r = device_path_make_major_minor(S_IFCHR, devnr, &fn);
 974                         if (r < 0)
 975                                 return r;
 976                 }
 977         }
 978
 979         if (!b) {
 980                 const char *w;
 981
 982                 w = path_startswith(fn, "/dev/");
 983                 if (w) {
 984                         b = strdup(w);
 985                         if (!b)
 986                                 return -ENOMEM;
 987                 } else
 988                         b = TAKE_PTR(fn);
 989         }
 990
 991         if (ret)
 992                 *ret = TAKE_PTR(b);
 993
 994         if (ret_devnr)
 995                 *ret_devnr = devnr;
 996
 997         return 0;
 998 }
 999
1000 int ptsname_malloc(int fd, char **ret) {
1001         size_t l = 100;
1002
1003         assert(fd >= 0);
1004         assert(ret);
1005
1006         for (;;) {
1007                 char *c;
1008
1009                 c = new(char, l);
1010                 if (!c)
1011                         return -ENOMEM;
1012
1013                 if (ptsname_r(fd, c, l) == 0) {
1014                         *ret = c;
1015                         return 0;
1016                 }
1017                 if (errno != ERANGE) {
1018                         free(c);
1019                         return -errno;
1020                 }
1021
1022                 free(c);
1023
1024                 if (l > SIZE_MAX / 2)
1025                         return -ENOMEM;
1026
1027                 l *= 2;
1028         }
1029 }
1030
1031 int openpt_allocate(int flags, char **ret_slave) {
1032         _cleanup_close_ int fd = -1;
1033         _cleanup_free_ char *p = NULL;
1034         int r;
1035
1036         fd = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1037         if (fd < 0)
1038                 return -errno;
1039
1040         if (ret_slave) {
1041                 r = ptsname_malloc(fd, &p);
1042                 if (r < 0)
1043                         return r;
1044
1045                 if (!path_startswith(p, "/dev/pts/"))
1046                         return -EINVAL;
1047         }
1048
1049         if (unlockpt(fd) < 0)
1050                 return -errno;
1051
1052         if (ret_slave)
1053                 *ret_slave = TAKE_PTR(p);
1054
1055         return TAKE_FD(fd);
1056 }
1057
1058 static int ptsname_namespace(int pty, char **ret) {
1059         int no = -1, r;
1060
1061         /* Like ptsname(), but doesn't assume that the path is
1062          * accessible in the local namespace. */
1063
1064         r = ioctl(pty, TIOCGPTN, &no);
1065         if (r < 0)
1066                 return -errno;
1067
1068         if (no < 0)
1069                 return -EIO;
1070
1071         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1072                 return -ENOMEM;
1073
1074         return 0;
1075 }
1076
1077 int openpt_allocate_in_namespace(pid_t pid, int flags, char **ret_slave) {
1078         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1, fd = -1;
1079         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1080         pid_t child;
1081         int r;
1082
1083         assert(pid > 0);
1084
1085         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1086         if (r < 0)
1087                 return r;
1088
1089         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1090                 return -errno;
1091
1092         r = namespace_fork("(sd-openptns)", "(sd-openpt)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
1093                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1094         if (r < 0)
1095                 return r;
1096         if (r == 0) {
1097                 pair[0] = safe_close(pair[0]);
1098
1099                 fd = openpt_allocate(flags, NULL);
1100                 if (fd < 0)
1101                         _exit(EXIT_FAILURE);
1102
1103                 if (send_one_fd(pair[1], fd, 0) < 0)
1104                         _exit(EXIT_FAILURE);
1105
1106                 _exit(EXIT_SUCCESS);
1107         }
1108
1109         pair[1] = safe_close(pair[1]);
1110
1111         r = wait_for_terminate_and_check("(sd-openptns)", child, 0);
1112         if (r < 0)
1113                 return r;
1114         if (r != EXIT_SUCCESS)
1115                 return -EIO;
1116
1117         fd = receive_one_fd(pair[0], 0);
1118         if (fd < 0)
1119                 return fd;
1120
1121         if (ret_slave) {
1122                 r = ptsname_namespace(fd, ret_slave);
1123                 if (r < 0)
1124                         return r;
1125         }
1126
1127         return TAKE_FD(fd);
1128 }
1129
1130 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1131         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1132         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1133         pid_t child;
1134         int r;
1135
1136         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1137         if (r < 0)
1138                 return r;
1139
1140         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1141                 return -errno;
1142
1143         r = namespace_fork("(sd-terminalns)", "(sd-terminal)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
1144                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1145         if (r < 0)
1146                 return r;
1147         if (r == 0) {
1148                 int master;
1149
1150                 pair[0] = safe_close(pair[0]);
1151
1152                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1153                 if (master < 0)
1154                         _exit(EXIT_FAILURE);
1155
1156                 if (send_one_fd(pair[1], master, 0) < 0)
1157                         _exit(EXIT_FAILURE);
1158
1159                 _exit(EXIT_SUCCESS);
1160         }
1161
1162         pair[1] = safe_close(pair[1]);
1163
1164         r = wait_for_terminate_and_check("(sd-terminalns)", child, 0);
1165         if (r < 0)
1166                 return r;
1167         if (r != EXIT_SUCCESS)
1168                 return -EIO;
1169
1170         return receive_one_fd(pair[0], 0);
1171 }
1172
1173 static bool getenv_terminal_is_dumb(void) {
1174         const char *e;
1175
1176         e = getenv("TERM");
1177         if (!e)
1178                 return true;
1179
1180         return streq(e, "dumb");
1181 }
1182
1183 bool terminal_is_dumb(void) {
1184         if (!on_tty())
1185                 return true;
1186
1187         return getenv_terminal_is_dumb();
1188 }
1189
1190 bool colors_enabled(void) {
1191
1192         /* Returns true if colors are considered supported on our stdout. For that we check $SYSTEMD_COLORS first
1193          * (which is the explicit way to turn colors on/off). If that didn't work we turn colors off unless we are on a
1194          * 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
1195          * we are PID 1 then we do not check whether we are connected to a TTY, because we don't keep /dev/console open
1196          * continuously due to fear of SAK, and hence things are a bit weird. */
1197
1198         if (cached_colors_enabled < 0) {
1199                 int val;
1200
1201                 val = getenv_bool("SYSTEMD_COLORS");
1202                 if (val >= 0)
1203                         cached_colors_enabled = val;
1204                 else if (getpid_cached() == 1)
1205                         /* PID1 outputs to the console without holding it open all the time */
1206                         cached_colors_enabled = !getenv_terminal_is_dumb();
1207                 else
1208                         cached_colors_enabled = !terminal_is_dumb();
1209         }
1210
1211         return cached_colors_enabled;
1212 }
1213
1214 bool dev_console_colors_enabled(void) {
1215         _cleanup_free_ char *s = NULL;
1216         int b;
1217
1218         /* Returns true if we assume that color is supported on /dev/console.
1219          *
1220          * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
1221          * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
1222          * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
1223          * colors_enabled() operates. */
1224
1225         b = getenv_bool("SYSTEMD_COLORS");
1226         if (b >= 0)
1227                 return b;
1228
1229         if (getenv_for_pid(1, "TERM", &s) <= 0)
1230                 (void) proc_cmdline_get_key("TERM", 0, &s);
1231
1232         return !streq_ptr(s, "dumb");
1233 }
1234
1235 bool underline_enabled(void) {
1236
1237         if (cached_underline_enabled < 0) {
1238
1239                 /* The Linux console doesn't support underlining, turn it off, but only there. */
1240
1241                 if (colors_enabled())
1242                         cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
1243                 else
1244                         cached_underline_enabled = false;
1245         }
1246
1247         return cached_underline_enabled;
1248 }
1249
1250 int vt_default_utf8(void) {
1251         _cleanup_free_ char *b = NULL;
1252         int r;
1253
1254         /* Read the default VT UTF8 setting from the kernel */
1255
1256         r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
1257         if (r < 0)
1258                 return r;
1259
1260         return parse_boolean(b);
1261 }
1262
1263 int vt_reset_keyboard(int fd) {
1264         int kb;
1265
1266         /* If we can't read the default, then default to unicode. It's 2017 after all. */
1267         kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
1268
1269         if (ioctl(fd, KDSKBMODE, kb) < 0)
1270                 return -errno;
1271
1272         return 0;
1273 }
1274
1275 int vt_restore(int fd) {
1276         static const struct vt_mode mode = {
1277                 .mode = VT_AUTO,
1278         };
1279         int r, q = 0;
1280
1281         if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
1282                 q = log_debug_errno(errno, "Failed to set VT in text mode, ignoring: %m");
1283
1284         r = vt_reset_keyboard(fd);
1285         if (r < 0) {
1286                 log_debug_errno(r, "Failed to reset keyboard mode, ignoring: %m");
1287                 if (q >= 0)
1288                         q = r;
1289         }
1290
1291         if (ioctl(fd, VT_SETMODE, &mode) < 0) {
1292                 log_debug_errno(errno, "Failed to set VT_AUTO mode, ignoring: %m");
1293                 if (q >= 0)
1294                         q = -errno;
1295         }
1296
1297         r = fchmod_and_chown(fd, TTY_MODE, 0, (gid_t) -1);
1298         if (r < 0) {
1299                 log_debug_errno(r, "Failed to chmod()/chown() VT, ignoring: %m");
1300                 if (q >= 0)
1301                         q = r;
1302         }
1303
1304         return q;
1305 }
1306
1307 int vt_release(int fd, bool restore) {
1308         assert(fd >= 0);
1309
1310         /* This function releases the VT by acknowledging the VT-switch signal
1311          * sent by the kernel and optionally reset the VT in text and auto
1312          * VT-switching modes. */
1313
1314         if (ioctl(fd, VT_RELDISP, 1) < 0)
1315                 return -errno;
1316
1317         if (restore)
1318                 return vt_restore(fd);
1319
1320         return 0;
1321 }
1322
1323 void get_log_colors(int priority, const char **on, const char **off, const char **highlight) {
1324         /* Note that this will initialize output variables only when there's something to output.
1325          * The caller must pre-initalize to "" or NULL as appropriate. */
1326
1327         if (priority <= LOG_ERR) {
1328                 if (on)
1329                         *on = ANSI_HIGHLIGHT_RED;
1330                 if (off)
1331                         *off = ANSI_NORMAL;
1332                 if (highlight)
1333                         *highlight = ANSI_HIGHLIGHT;
1334
1335         } else if (priority <= LOG_WARNING) {
1336                 if (on)
1337                         *on = ANSI_HIGHLIGHT_YELLOW;
1338                 if (off)
1339                         *off = ANSI_NORMAL;
1340                 if (highlight)
1341                         *highlight = ANSI_HIGHLIGHT;
1342
1343         } else if (priority <= LOG_NOTICE) {
1344                 if (on)
1345                         *on = ANSI_HIGHLIGHT;
1346                 if (off)
1347                         *off = ANSI_NORMAL;
1348                 if (highlight)
1349                         *highlight = ANSI_HIGHLIGHT_RED;
1350
1351         } else if (priority >= LOG_DEBUG) {
1352                 if (on)
1353                         *on = ANSI_GREY;
1354                 if (off)
1355                         *off = ANSI_NORMAL;
1356                 if (highlight)
1357                         *highlight = ANSI_HIGHLIGHT_RED;
1358         }
1359 }