src/basic/terminal-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   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 <sys/inotify.h>
  15 #include <sys/ioctl.h>
  16 #include <sys/sysmacros.h>
  17 #include <sys/time.h>
  18 #include <sys/types.h>
  19 #include <sys/utsname.h>
  20 #include <termios.h>
  21 #include <unistd.h>
  22
  23 #include "alloc-util.h"
  24 #include "constants.h"
  25 #include "devnum-util.h"
  26 #include "env-util.h"
  27 #include "fd-util.h"
  28 #include "fileio.h"
  29 #include "fs-util.h"
  30 #include "inotify-util.h"
  31 #include "io-util.h"
  32 #include "log.h"
  33 #include "macro.h"
  34 #include "namespace-util.h"
  35 #include "parse-util.h"
  36 #include "path-util.h"
  37 #include "proc-cmdline.h"
  38 #include "process-util.h"
  39 #include "socket-util.h"
  40 #include "stat-util.h"
  41 #include "stdio-util.h"
  42 #include "string-util.h"
  43 #include "strv.h"
  44 #include "terminal-util.h"
  45 #include "time-util.h"
  46 #include "user-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_on_dev_null = -1;
  53 static volatile int cached_color_mode = _COLOR_INVALID;
  54 static volatile int cached_underline_enabled = -1;
  55
  56 int chvt(int vt) {
  57         _cleanup_close_ int fd = -EBADF;
  58
  59         /* Switch to the specified vt number. If the VT is specified <= 0 switch to the VT the kernel log messages go,
  60          * if that's configured. */
  61
  62         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
  63         if (fd < 0)
  64                 return -errno;
  65
  66         if (vt <= 0) {
  67                 int tiocl[2] = {
  68                         TIOCL_GETKMSGREDIRECT,
  69                         0
  70                 };
  71
  72                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  73                         return -errno;
  74
  75                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  76         }
  77
  78         return RET_NERRNO(ioctl(fd, VT_ACTIVATE, vt));
  79 }
  80
  81 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  82         _cleanup_free_ char *line = NULL;
  83         struct termios old_termios;
  84         int r, fd;
  85
  86         assert(f);
  87         assert(ret);
  88
  89         /* If this is a terminal, then switch canonical mode off, so that we can read a single
  90          * character. (Note that fmemopen() streams do not have an fd associated with them, let's handle that
  91          * nicely.) */
  92         fd = fileno(f);
  93         if (fd >= 0 && tcgetattr(fd, &old_termios) >= 0) {
  94                 struct termios 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(fd, TCSADRAIN, &new_termios) >= 0) {
 101                         char c;
 102
 103                         if (t != USEC_INFINITY) {
 104                                 if (fd_wait_for_event(fd, POLLIN, t) <= 0) {
 105                                         (void) tcsetattr(fd, TCSADRAIN, &old_termios);
 106                                         return -ETIMEDOUT;
 107                                 }
 108                         }
 109
 110                         r = safe_fgetc(f, &c);
 111                         (void) tcsetattr(fd, TCSADRAIN, &old_termios);
 112                         if (r < 0)
 113                                 return r;
 114                         if (r == 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 && fd > 0) {
 126                 /* Let's wait the specified amount of time for input. When we have no fd we skip this, under
 127                  * the assumption that this is an fmemopen() stream or so where waiting doesn't make sense
 128                  * anyway, as the data is either already in the stream or cannot possible be placed there
 129                  * while we access the stream */
 130
 131                 if (fd_wait_for_event(fd, POLLIN, t) <= 0)
 132                         return -ETIMEDOUT;
 133         }
 134
 135         /* If this is not a terminal, then read a full line instead */
 136
 137         r = read_line(f, 16, &line); /* longer than necessary, to eat up UTF-8 chars/vt100 key sequences */
 138         if (r < 0)
 139                 return r;
 140         if (r == 0)
 141                 return -EIO;
 142
 143         if (strlen(line) != 1)
 144                 return -EBADMSG;
 145
 146         if (need_nl)
 147                 *need_nl = false;
 148
 149         *ret = line[0];
 150         return 0;
 151 }
 152
 153 #define DEFAULT_ASK_REFRESH_USEC (2*USEC_PER_SEC)
 154
 155 int ask_char(char *ret, const char *replies, const char *fmt, ...) {
 156         int r;
 157
 158         assert(ret);
 159         assert(replies);
 160         assert(fmt);
 161
 162         for (;;) {
 163                 va_list ap;
 164                 char c;
 165                 bool need_nl = true;
 166
 167                 fputs(ansi_highlight(), stdout);
 168
 169                 putchar('\r');
 170
 171                 va_start(ap, fmt);
 172                 vprintf(fmt, ap);
 173                 va_end(ap);
 174
 175                 fputs(ansi_normal(), stdout);
 176
 177                 fflush(stdout);
 178
 179                 r = read_one_char(stdin, &c, DEFAULT_ASK_REFRESH_USEC, &need_nl);
 180                 if (r < 0) {
 181
 182                         if (r == -ETIMEDOUT)
 183                                 continue;
 184
 185                         if (r == -EBADMSG) {
 186                                 puts("Bad input, please try again.");
 187                                 continue;
 188                         }
 189
 190                         putchar('\n');
 191                         return r;
 192                 }
 193
 194                 if (need_nl)
 195                         putchar('\n');
 196
 197                 if (strchr(replies, c)) {
 198                         *ret = c;
 199                         return 0;
 200                 }
 201
 202                 puts("Read unexpected character, please try again.");
 203         }
 204 }
 205
 206 int ask_string(char **ret, const char *text, ...) {
 207         _cleanup_free_ char *line = NULL;
 208         va_list ap;
 209         int r;
 210
 211         assert(ret);
 212         assert(text);
 213
 214         fputs(ansi_highlight(), stdout);
 215
 216         va_start(ap, text);
 217         vprintf(text, ap);
 218         va_end(ap);
 219
 220         fputs(ansi_normal(), stdout);
 221
 222         fflush(stdout);
 223
 224         r = read_line(stdin, LONG_LINE_MAX, &line);
 225         if (r < 0)
 226                 return r;
 227         if (r == 0)
 228                 return -EIO;
 229
 230         *ret = TAKE_PTR(line);
 231         return 0;
 232 }
 233
 234 int reset_terminal_fd(int fd, bool switch_to_text) {
 235         struct termios termios;
 236         int r;
 237
 238         /* Set terminal to some sane defaults */
 239
 240         assert(fd >= 0);
 241
 242         if (isatty(fd) < 1)
 243                 return log_debug_errno(errno, "Asked to reset a terminal that actually isn't a terminal: %m");
 244
 245         /* We leave locked terminal attributes untouched, so that Plymouth may set whatever it wants to set,
 246          * and we don't interfere with that. */
 247
 248         /* Disable exclusive mode, just in case */
 249         if (ioctl(fd, TIOCNXCL) < 0)
 250                 log_debug_errno(errno, "TIOCNXCL ioctl failed on TTY, ignoring: %m");
 251
 252         /* Switch to text mode */
 253         if (switch_to_text)
 254                 if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
 255                         log_debug_errno(errno, "KDSETMODE ioctl for switching to text mode failed on TTY, ignoring: %m");
 256
 257
 258         /* Set default keyboard mode */
 259         r = vt_reset_keyboard(fd);
 260         if (r < 0)
 261                 log_debug_errno(r, "Failed to reset VT keyboard, ignoring: %m");
 262
 263         if (tcgetattr(fd, &termios) < 0) {
 264                 r = log_debug_errno(errno, "Failed to get terminal parameters: %m");
 265                 goto finish;
 266         }
 267
 268         /* We only reset the stuff that matters to the software. How
 269          * hardware is set up we don't touch assuming that somebody
 270          * else will do that for us */
 271
 272         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 273         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 274         termios.c_oflag |= ONLCR | OPOST;
 275         termios.c_cflag |= CREAD;
 276         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE;
 277
 278         termios.c_cc[VINTR]    =   03;  /* ^C */
 279         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 280         termios.c_cc[VERASE]   = 0177;
 281         termios.c_cc[VKILL]    =  025;  /* ^X */
 282         termios.c_cc[VEOF]     =   04;  /* ^D */
 283         termios.c_cc[VSTART]   =  021;  /* ^Q */
 284         termios.c_cc[VSTOP]    =  023;  /* ^S */
 285         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 286         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 287         termios.c_cc[VWERASE]  =  027;  /* ^W */
 288         termios.c_cc[VREPRINT] =  022;  /* ^R */
 289         termios.c_cc[VEOL]     =    0;
 290         termios.c_cc[VEOL2]    =    0;
 291
 292         termios.c_cc[VTIME]  = 0;
 293         termios.c_cc[VMIN]   = 1;
 294
 295         r = RET_NERRNO(tcsetattr(fd, TCSANOW, &termios));
 296
 297 finish:
 298         /* Just in case, flush all crap out */
 299         (void) tcflush(fd, TCIOFLUSH);
 300
 301         return r;
 302 }
 303
 304 int reset_terminal(const char *name) {
 305         _cleanup_close_ int fd = -EBADF;
 306
 307         /* We open the terminal with O_NONBLOCK here, to ensure we
 308          * don't block on carrier if this is a terminal with carrier
 309          * configured. */
 310
 311         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 312         if (fd < 0)
 313                 return fd;
 314
 315         return reset_terminal_fd(fd, true);
 316 }
 317
 318 int open_terminal(const char *name, int mode) {
 319         _cleanup_close_ int fd = -EBADF;
 320         unsigned c = 0;
 321
 322         /*
 323          * If a TTY is in the process of being closed opening it might cause EIO. This is horribly awful, but
 324          * unlikely to be changed in the kernel. Hence we work around this problem by retrying a couple of
 325          * times.
 326          *
 327          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 328          */
 329
 330         if (mode & O_CREAT)
 331                 return -EINVAL;
 332
 333         for (;;) {
 334                 fd = open(name, mode, 0);
 335                 if (fd >= 0)
 336                         break;
 337
 338                 if (errno != EIO)
 339                         return -errno;
 340
 341                 /* Max 1s in total */
 342                 if (c >= 20)
 343                         return -errno;
 344
 345                 (void) usleep_safe(50 * USEC_PER_MSEC);
 346                 c++;
 347         }
 348
 349         if (isatty(fd) < 1)
 350                 return negative_errno();
 351
 352         return TAKE_FD(fd);
 353 }
 354
 355 int acquire_terminal(
 356                 const char *name,
 357                 AcquireTerminalFlags flags,
 358                 usec_t timeout) {
 359
 360         _cleanup_close_ int notify = -EBADF, fd = -EBADF;
 361         usec_t ts = USEC_INFINITY;
 362         int r, wd = -1;
 363
 364         assert(name);
 365         assert(IN_SET(flags & ~ACQUIRE_TERMINAL_PERMISSIVE, ACQUIRE_TERMINAL_TRY, ACQUIRE_TERMINAL_FORCE, ACQUIRE_TERMINAL_WAIT));
 366
 367         /* We use inotify to be notified when the tty is closed. We create the watch before checking if we can actually
 368          * acquire it, so that we don't lose any event.
 369          *
 370          * Note: strictly speaking this actually watches for the device being closed, it does *not* really watch
 371          * whether a tty loses its controlling process. However, unless some rogue process uses TIOCNOTTY on /dev/tty
 372          * *after* closing its tty otherwise this will not become a problem. As long as the administrator makes sure to
 373          * not configure any service on the same tty as an untrusted user this should not be a problem. (Which they
 374          * probably should not do anyway.) */
 375
 376         if ((flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_WAIT) {
 377                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 378                 if (notify < 0)
 379                         return -errno;
 380
 381                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 382                 if (wd < 0)
 383                         return -errno;
 384
 385                 if (timeout != USEC_INFINITY)
 386                         ts = now(CLOCK_MONOTONIC);
 387         }
 388
 389         for (;;) {
 390                 struct sigaction sa_old, sa_new = {
 391                         .sa_handler = SIG_IGN,
 392                         .sa_flags = SA_RESTART,
 393                 };
 394
 395                 if (notify >= 0) {
 396                         r = flush_fd(notify);
 397                         if (r < 0)
 398                                 return r;
 399                 }
 400
 401                 /* We pass here O_NOCTTY only so that we can check the return value TIOCSCTTY and have a reliable way
 402                  * to figure out if we successfully became the controlling process of the tty */
 403                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 404                 if (fd < 0)
 405                         return fd;
 406
 407                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed if we already own the tty. */
 408                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 409
 410                 /* First, try to get the tty */
 411                 r = RET_NERRNO(ioctl(fd, TIOCSCTTY, (flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_FORCE));
 412
 413                 /* Reset signal handler to old value */
 414                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 415
 416                 /* Success? Exit the loop now! */
 417                 if (r >= 0)
 418                         break;
 419
 420                 /* Any failure besides -EPERM? Fail, regardless of the mode. */
 421                 if (r != -EPERM)
 422                         return r;
 423
 424                 if (flags & ACQUIRE_TERMINAL_PERMISSIVE) /* If we are in permissive mode, then EPERM is fine, turn this
 425                                                           * into a success. Note that EPERM is also returned if we
 426                                                           * already are the owner of the TTY. */
 427                         break;
 428
 429                 if (flags != ACQUIRE_TERMINAL_WAIT) /* If we are in TRY or FORCE mode, then propagate EPERM as EPERM */
 430                         return r;
 431
 432                 assert(notify >= 0);
 433                 assert(wd >= 0);
 434
 435                 for (;;) {
 436                         union inotify_event_buffer buffer;
 437                         ssize_t l;
 438
 439                         if (timeout != USEC_INFINITY) {
 440                                 usec_t n;
 441
 442                                 assert(ts != USEC_INFINITY);
 443
 444                                 n = usec_sub_unsigned(now(CLOCK_MONOTONIC), ts);
 445                                 if (n >= timeout)
 446                                         return -ETIMEDOUT;
 447
 448                                 r = fd_wait_for_event(notify, POLLIN, usec_sub_unsigned(timeout, n));
 449                                 if (r < 0)
 450                                         return r;
 451                                 if (r == 0)
 452                                         return -ETIMEDOUT;
 453                         }
 454
 455                         l = read(notify, &buffer, sizeof(buffer));
 456                         if (l < 0) {
 457                                 if (ERRNO_IS_TRANSIENT(errno))
 458                                         continue;
 459
 460                                 return -errno;
 461                         }
 462
 463                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 464                                 if (e->mask & IN_Q_OVERFLOW) /* If we hit an inotify queue overflow, simply check if the terminal is up for grabs now. */
 465                                         break;
 466
 467                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) /* Safety checks */
 468                                         return -EIO;
 469                         }
 470
 471                         break;
 472                 }
 473
 474                 /* We close the tty fd here since if the old session ended our handle will be dead. It's important that
 475                  * we do this after sleeping, so that we don't enter an endless loop. */
 476                 fd = safe_close(fd);
 477         }
 478
 479         return TAKE_FD(fd);
 480 }
 481
 482 int release_terminal(void) {
 483         static const struct sigaction sa_new = {
 484                 .sa_handler = SIG_IGN,
 485                 .sa_flags = SA_RESTART,
 486         };
 487
 488         _cleanup_close_ int fd = -EBADF;
 489         struct sigaction sa_old;
 490         int r;
 491
 492         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 493         if (fd < 0)
 494                 return -errno;
 495
 496         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 497          * by our own TIOCNOTTY */
 498         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 499
 500         r = RET_NERRNO(ioctl(fd, TIOCNOTTY));
 501
 502         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 503
 504         return r;
 505 }
 506
 507 int terminal_vhangup_fd(int fd) {
 508         assert(fd >= 0);
 509         return RET_NERRNO(ioctl(fd, TIOCVHANGUP));
 510 }
 511
 512 int terminal_vhangup(const char *name) {
 513         _cleanup_close_ int fd = -EBADF;
 514
 515         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 516         if (fd < 0)
 517                 return fd;
 518
 519         return terminal_vhangup_fd(fd);
 520 }
 521
 522 int vt_disallocate(const char *name) {
 523         const char *e;
 524         int r;
 525
 526         /* Deallocate the VT if possible. If not possible
 527          * (i.e. because it is the active one), at least clear it
 528          * entirely (including the scrollback buffer). */
 529
 530         e = path_startswith(name, "/dev/");
 531         if (!e)
 532                 return -EINVAL;
 533
 534         if (tty_is_vc(name)) {
 535                 _cleanup_close_ int fd = -EBADF;
 536                 unsigned u;
 537                 const char *n;
 538
 539                 n = startswith(e, "tty");
 540                 if (!n)
 541                         return -EINVAL;
 542
 543                 r = safe_atou(n, &u);
 544                 if (r < 0)
 545                         return r;
 546
 547                 if (u <= 0)
 548                         return -EINVAL;
 549
 550                 /* Try to deallocate */
 551                 fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 552                 if (fd < 0)
 553                         return fd;
 554
 555                 r = ioctl(fd, VT_DISALLOCATE, u);
 556                 if (r >= 0)
 557                         return 0;
 558                 if (errno != EBUSY)
 559                         return -errno;
 560         }
 561
 562         /* So this is not a VT (in which case we cannot deallocate it),
 563          * or we failed to deallocate. Let's at least clear the screen. */
 564
 565         _cleanup_close_ int fd2 = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 566         if (fd2 < 0)
 567                 return fd2;
 568
 569         (void) loop_write(fd2,
 570                           "\033[r"   /* clear scrolling region */
 571                           "\033[H"   /* move home */
 572                           "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 573                           10);
 574         return 0;
 575 }
 576
 577 int make_console_stdio(void) {
 578         int fd, r;
 579
 580         /* Make /dev/console the controlling terminal and stdin/stdout/stderr, if we can. If we can't use
 581          * /dev/null instead. This is particularly useful if /dev/console is turned off, e.g. if console=null
 582          * is specified on the kernel command line. */
 583
 584         fd = acquire_terminal("/dev/console", ACQUIRE_TERMINAL_FORCE|ACQUIRE_TERMINAL_PERMISSIVE, USEC_INFINITY);
 585         if (fd < 0) {
 586                 log_warning_errno(fd, "Failed to acquire terminal, using /dev/null stdin/stdout/stderr instead: %m");
 587
 588                 r = make_null_stdio();
 589                 if (r < 0)
 590                         return log_error_errno(r, "Failed to make /dev/null stdin/stdout/stderr: %m");
 591
 592         } else {
 593                 unsigned rows, cols;
 594
 595                 r = reset_terminal_fd(fd, /* switch_to_text= */ true);
 596                 if (r < 0)
 597                         log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 598
 599                 r = proc_cmdline_tty_size("/dev/console", &rows, &cols);
 600                 if (r < 0)
 601                         log_warning_errno(r, "Failed to get terminal size, ignoring: %m");
 602                 else {
 603                         r = terminal_set_size_fd(fd, NULL, rows, cols);
 604                         if (r < 0)
 605                                 log_warning_errno(r, "Failed to set terminal size, ignoring: %m");
 606                 }
 607
 608                 r = rearrange_stdio(fd, fd, fd); /* This invalidates 'fd' both on success and on failure. */
 609                 if (r < 0)
 610                         return log_error_errno(r, "Failed to make terminal stdin/stdout/stderr: %m");
 611         }
 612
 613         reset_terminal_feature_caches();
 614         return 0;
 615 }
 616
 617 bool tty_is_vc(const char *tty) {
 618         assert(tty);
 619
 620         return vtnr_from_tty(tty) >= 0;
 621 }
 622
 623 bool tty_is_console(const char *tty) {
 624         assert(tty);
 625
 626         return streq(skip_dev_prefix(tty), "console");
 627 }
 628
 629 int vtnr_from_tty(const char *tty) {
 630         int i, r;
 631
 632         assert(tty);
 633
 634         tty = skip_dev_prefix(tty);
 635
 636         if (!startswith(tty, "tty") )
 637                 return -EINVAL;
 638
 639         if (!ascii_isdigit(tty[3]))
 640                 return -EINVAL;
 641
 642         r = safe_atoi(tty+3, &i);
 643         if (r < 0)
 644                 return r;
 645
 646         if (i < 0 || i > 63)
 647                 return -EINVAL;
 648
 649         return i;
 650 }
 651
 652  int resolve_dev_console(char **ret) {
 653         _cleanup_free_ char *active = NULL;
 654         char *tty;
 655         int r;
 656
 657         assert(ret);
 658
 659         /* Resolve where /dev/console is pointing to, if /sys is actually ours (i.e. not read-only-mounted which is a
 660          * sign for container setups) */
 661
 662         if (path_is_read_only_fs("/sys") > 0)
 663                 return -ENOMEDIUM;
 664
 665         r = read_one_line_file("/sys/class/tty/console/active", &active);
 666         if (r < 0)
 667                 return r;
 668
 669         /* If multiple log outputs are configured the last one is what /dev/console points to */
 670         tty = strrchr(active, ' ');
 671         if (tty)
 672                 tty++;
 673         else
 674                 tty = active;
 675
 676         if (streq(tty, "tty0")) {
 677                 active = mfree(active);
 678
 679                 /* Get the active VC (e.g. tty1) */
 680                 r = read_one_line_file("/sys/class/tty/tty0/active", &active);
 681                 if (r < 0)
 682                         return r;
 683
 684                 tty = active;
 685         }
 686
 687         if (tty == active)
 688                 *ret = TAKE_PTR(active);
 689         else {
 690                 char *tmp;
 691
 692                 tmp = strdup(tty);
 693                 if (!tmp)
 694                         return -ENOMEM;
 695
 696                 *ret = tmp;
 697         }
 698
 699         return 0;
 700 }
 701
 702 int get_kernel_consoles(char ***ret) {
 703         _cleanup_strv_free_ char **l = NULL;
 704         _cleanup_free_ char *line = NULL;
 705         const char *p;
 706         int r;
 707
 708         assert(ret);
 709
 710         /* If /sys is mounted read-only this means we are running in some kind of container environment. In that
 711          * case /sys would reflect the host system, not us, hence ignore the data we can read from it. */
 712         if (path_is_read_only_fs("/sys") > 0)
 713                 goto fallback;
 714
 715         r = read_one_line_file("/sys/class/tty/console/active", &line);
 716         if (r < 0)
 717                 return r;
 718
 719         p = line;
 720         for (;;) {
 721                 _cleanup_free_ char *tty = NULL, *path = NULL;
 722
 723                 r = extract_first_word(&p, &tty, NULL, 0);
 724                 if (r < 0)
 725                         return r;
 726                 if (r == 0)
 727                         break;
 728
 729                 if (streq(tty, "tty0")) {
 730                         tty = mfree(tty);
 731                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 732                         if (r < 0)
 733                                 return r;
 734                 }
 735
 736                 path = path_join("/dev", tty);
 737                 if (!path)
 738                         return -ENOMEM;
 739
 740                 if (access(path, F_OK) < 0) {
 741                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 742                         continue;
 743                 }
 744
 745                 r = strv_consume(&l, TAKE_PTR(path));
 746                 if (r < 0)
 747                         return r;
 748         }
 749
 750         if (strv_isempty(l)) {
 751                 log_debug("No devices found for system console");
 752                 goto fallback;
 753         }
 754
 755         *ret = TAKE_PTR(l);
 756
 757         return 0;
 758
 759 fallback:
 760         r = strv_extend(&l, "/dev/console");
 761         if (r < 0)
 762                 return r;
 763
 764         *ret = TAKE_PTR(l);
 765
 766         return 0;
 767 }
 768
 769 bool tty_is_vc_resolve(const char *tty) {
 770         _cleanup_free_ char *resolved = NULL;
 771
 772         assert(tty);
 773
 774         tty = skip_dev_prefix(tty);
 775
 776         if (streq(tty, "console")) {
 777                 if (resolve_dev_console(&resolved) < 0)
 778                         return false;
 779
 780                 tty = resolved;
 781         }
 782
 783         return tty_is_vc(tty);
 784 }
 785
 786 const char *default_term_for_tty(const char *tty) {
 787         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 788 }
 789
 790 int fd_columns(int fd) {
 791         struct winsize ws = {};
 792
 793         if (fd < 0)
 794                 return -EBADF;
 795
 796         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 797                 return -errno;
 798
 799         if (ws.ws_col <= 0)
 800                 return -EIO;
 801
 802         return ws.ws_col;
 803 }
 804
 805 unsigned columns(void) {
 806         const char *e;
 807         int c;
 808
 809         if (cached_columns > 0)
 810                 return cached_columns;
 811
 812         c = 0;
 813         e = getenv("COLUMNS");
 814         if (e)
 815                 (void) safe_atoi(e, &c);
 816
 817         if (c <= 0 || c > USHRT_MAX) {
 818                 c = fd_columns(STDOUT_FILENO);
 819                 if (c <= 0)
 820                         c = 80;
 821         }
 822
 823         cached_columns = c;
 824         return cached_columns;
 825 }
 826
 827 int fd_lines(int fd) {
 828         struct winsize ws = {};
 829
 830         if (fd < 0)
 831                 return -EBADF;
 832
 833         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 834                 return -errno;
 835
 836         if (ws.ws_row <= 0)
 837                 return -EIO;
 838
 839         return ws.ws_row;
 840 }
 841
 842 unsigned lines(void) {
 843         const char *e;
 844         int l;
 845
 846         if (cached_lines > 0)
 847                 return cached_lines;
 848
 849         l = 0;
 850         e = getenv("LINES");
 851         if (e)
 852                 (void) safe_atoi(e, &l);
 853
 854         if (l <= 0 || l > USHRT_MAX) {
 855                 l = fd_lines(STDOUT_FILENO);
 856                 if (l <= 0)
 857                         l = 24;
 858         }
 859
 860         cached_lines = l;
 861         return cached_lines;
 862 }
 863
 864 int terminal_set_size_fd(int fd, const char *ident, unsigned rows, unsigned cols) {
 865         struct winsize ws;
 866
 867         if (rows == UINT_MAX && cols == UINT_MAX)
 868                 return 0;
 869
 870         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 871                 return log_debug_errno(errno,
 872                                        "TIOCGWINSZ ioctl for getting %s size failed, not setting terminal size: %m",
 873                                        ident ?: "TTY");
 874
 875         if (rows == UINT_MAX)
 876                 rows = ws.ws_row;
 877         else if (rows > USHRT_MAX)
 878                 rows = USHRT_MAX;
 879
 880         if (cols == UINT_MAX)
 881                 cols = ws.ws_col;
 882         else if (cols > USHRT_MAX)
 883                 cols = USHRT_MAX;
 884
 885         if (rows == ws.ws_row && cols == ws.ws_col)
 886                 return 0;
 887
 888         ws.ws_row = rows;
 889         ws.ws_col = cols;
 890
 891         if (ioctl(fd, TIOCSWINSZ, &ws) < 0)
 892                 return log_debug_errno(errno, "TIOCSWINSZ ioctl for setting %s size failed: %m", ident ?: "TTY");
 893
 894         return 0;
 895 }
 896
 897 int proc_cmdline_tty_size(const char *tty, unsigned *ret_rows, unsigned *ret_cols) {
 898         _cleanup_free_ char *rowskey = NULL, *rowsvalue = NULL, *colskey = NULL, *colsvalue = NULL;
 899         unsigned rows = UINT_MAX, cols = UINT_MAX;
 900         int r;
 901
 902         assert(tty);
 903
 904         if (!ret_rows && !ret_cols)
 905                 return 0;
 906
 907         tty = skip_dev_prefix(tty);
 908         if (!in_charset(tty, ALPHANUMERICAL))
 909                 return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "%s contains non-alphanumeric characters", tty);
 910
 911         rowskey = strjoin("systemd.tty.rows.", tty);
 912         if (!rowskey)
 913                 return -ENOMEM;
 914
 915         colskey = strjoin("systemd.tty.columns.", tty);
 916         if (!colskey)
 917                 return -ENOMEM;
 918
 919         r = proc_cmdline_get_key_many(/* flags = */ 0,
 920                                       rowskey, &rowsvalue,
 921                                       colskey, &colsvalue);
 922         if (r < 0)
 923                 return log_debug_errno(r, "Failed to read TTY size of %s from kernel cmdline: %m", tty);
 924
 925         if (rowsvalue) {
 926                 r = safe_atou(rowsvalue, &rows);
 927                 if (r < 0)
 928                         return log_debug_errno(r, "Failed to parse %s=%s: %m", rowskey, rowsvalue);
 929         }
 930
 931         if (colsvalue) {
 932                 r = safe_atou(colsvalue, &cols);
 933                 if (r < 0)
 934                         return log_debug_errno(r, "Failed to parse %s=%s: %m", colskey, colsvalue);
 935         }
 936
 937         if (ret_rows)
 938                 *ret_rows = rows;
 939         if (ret_cols)
 940                 *ret_cols = cols;
 941
 942         return 0;
 943 }
 944
 945 /* intended to be used as a SIGWINCH sighandler */
 946 void columns_lines_cache_reset(int signum) {
 947         cached_columns = 0;
 948         cached_lines = 0;
 949 }
 950
 951 void reset_terminal_feature_caches(void) {
 952         cached_columns = 0;
 953         cached_lines = 0;
 954
 955         cached_color_mode = _COLOR_INVALID;
 956         cached_underline_enabled = -1;
 957         cached_on_tty = -1;
 958         cached_on_dev_null = -1;
 959 }
 960
 961 bool on_tty(void) {
 962
 963         /* We check both stdout and stderr, so that situations where pipes on the shell are used are reliably
 964          * recognized, regardless if only the output or the errors are piped to some place. Since on_tty() is generally
 965          * used to default to a safer, non-interactive, non-color mode of operation it's probably good to be defensive
 966          * here, and check for both. Note that we don't check for STDIN_FILENO, because it should fine to use fancy
 967          * terminal functionality when outputting stuff, even if the input is piped to us. */
 968
 969         if (cached_on_tty < 0)
 970                 cached_on_tty =
 971                         isatty(STDOUT_FILENO) > 0 &&
 972                         isatty(STDERR_FILENO) > 0;
 973
 974         return cached_on_tty;
 975 }
 976
 977 int getttyname_malloc(int fd, char **ret) {
 978         char path[PATH_MAX], *c; /* PATH_MAX is counted *with* the trailing NUL byte */
 979         int r;
 980
 981         assert(fd >= 0);
 982         assert(ret);
 983
 984         r = ttyname_r(fd, path, sizeof path); /* positive error */
 985         assert(r >= 0);
 986         if (r == ERANGE)
 987                 return -ENAMETOOLONG;
 988         if (r > 0)
 989                 return -r;
 990
 991         c = strdup(skip_dev_prefix(path));
 992         if (!c)
 993                 return -ENOMEM;
 994
 995         *ret = c;
 996         return 0;
 997 }
 998
 999 int getttyname_harder(int fd, char **ret) {
1000         _cleanup_free_ char *s = NULL;
1001         int r;
1002
1003         r = getttyname_malloc(fd, &s);
1004         if (r < 0)
1005                 return r;
1006
1007         if (streq(s, "tty"))
1008                 return get_ctty(0, NULL, ret);
1009
1010         *ret = TAKE_PTR(s);
1011         return 0;
1012 }
1013
1014 int get_ctty_devnr(pid_t pid, dev_t *d) {
1015         int r;
1016         _cleanup_free_ char *line = NULL;
1017         const char *p;
1018         unsigned long ttynr;
1019
1020         assert(pid >= 0);
1021
1022         p = procfs_file_alloca(pid, "stat");
1023         r = read_one_line_file(p, &line);
1024         if (r < 0)
1025                 return r;
1026
1027         p = strrchr(line, ')');
1028         if (!p)
1029                 return -EIO;
1030
1031         p++;
1032
1033         if (sscanf(p, " "
1034                    "%*c "  /* state */
1035                    "%*d "  /* ppid */
1036                    "%*d "  /* pgrp */
1037                    "%*d "  /* session */
1038                    "%lu ", /* ttynr */
1039                    &ttynr) != 1)
1040                 return -EIO;
1041
1042         if (devnum_is_zero(ttynr))
1043                 return -ENXIO;
1044
1045         if (d)
1046                 *d = (dev_t) ttynr;
1047
1048         return 0;
1049 }
1050
1051 int get_ctty(pid_t pid, dev_t *ret_devnr, char **ret) {
1052         char pty[STRLEN("/dev/pts/") + DECIMAL_STR_MAX(dev_t) + 1];
1053         _cleanup_free_ char *buf = NULL;
1054         const char *fn = NULL, *w;
1055         dev_t devnr;
1056         int r;
1057
1058         r = get_ctty_devnr(pid, &devnr);
1059         if (r < 0)
1060                 return r;
1061
1062         r = device_path_make_canonical(S_IFCHR, devnr, &buf);
1063         if (r < 0) {
1064                 struct stat st;
1065
1066                 if (r != -ENOENT) /* No symlink for this in /dev/char/? */
1067                         return r;
1068
1069                 /* Maybe this is PTY? PTY devices are not listed in /dev/char/, as they don't follow the
1070                  * Linux device model and hence device_path_make_canonical() doesn't work for them. Let's
1071                  * assume this is a PTY for a moment, and check if the device node this would then map to in
1072                  * /dev/pts/ matches the one we are looking for. This way we don't have to hardcode the major
1073                  * number (which is 136 btw), but we still rely on the fact that PTY numbers map directly to
1074                  * the minor number of the pty. */
1075                 xsprintf(pty, "/dev/pts/%u", minor(devnr));
1076
1077                 if (stat(pty, &st) < 0) {
1078                         if (errno != ENOENT)
1079                                 return -errno;
1080
1081                 } else if (S_ISCHR(st.st_mode) && devnr == st.st_rdev) /* Bingo! */
1082                         fn = pty;
1083
1084                 if (!fn) {
1085                         /* Doesn't exist, or not a PTY? Probably something similar to the PTYs which have no
1086                          * symlink in /dev/char/. Let's return something vaguely useful. */
1087                         r = device_path_make_major_minor(S_IFCHR, devnr, &buf);
1088                         if (r < 0)
1089                                 return r;
1090
1091                         fn = buf;
1092                 }
1093         } else
1094                 fn = buf;
1095
1096         w = path_startswith(fn, "/dev/");
1097         if (!w)
1098                 return -EINVAL;
1099
1100         if (ret) {
1101                 _cleanup_free_ char *b = NULL;
1102
1103                 b = strdup(w);
1104                 if (!b)
1105                         return -ENOMEM;
1106
1107                 *ret = TAKE_PTR(b);
1108         }
1109
1110         if (ret_devnr)
1111                 *ret_devnr = devnr;
1112
1113         return 0;
1114 }
1115
1116 int ptsname_malloc(int fd, char **ret) {
1117         size_t l = 100;
1118
1119         assert(fd >= 0);
1120         assert(ret);
1121
1122         for (;;) {
1123                 char *c;
1124
1125                 c = new(char, l);
1126                 if (!c)
1127                         return -ENOMEM;
1128
1129                 if (ptsname_r(fd, c, l) == 0) {
1130                         *ret = c;
1131                         return 0;
1132                 }
1133                 if (errno != ERANGE) {
1134                         free(c);
1135                         return -errno;
1136                 }
1137
1138                 free(c);
1139
1140                 if (l > SIZE_MAX / 2)
1141                         return -ENOMEM;
1142
1143                 l *= 2;
1144         }
1145 }
1146
1147 int openpt_allocate(int flags, char **ret_slave) {
1148         _cleanup_close_ int fd = -EBADF;
1149         _cleanup_free_ char *p = NULL;
1150         int r;
1151
1152         fd = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1153         if (fd < 0)
1154                 return -errno;
1155
1156         if (ret_slave) {
1157                 r = ptsname_malloc(fd, &p);
1158                 if (r < 0)
1159                         return r;
1160
1161                 if (!path_startswith(p, "/dev/pts/"))
1162                         return -EINVAL;
1163         }
1164
1165         if (unlockpt(fd) < 0)
1166                 return -errno;
1167
1168         if (ret_slave)
1169                 *ret_slave = TAKE_PTR(p);
1170
1171         return TAKE_FD(fd);
1172 }
1173
1174 static int ptsname_namespace(int pty, char **ret) {
1175         int no = -1, r;
1176
1177         /* Like ptsname(), but doesn't assume that the path is
1178          * accessible in the local namespace. */
1179
1180         r = ioctl(pty, TIOCGPTN, &no);
1181         if (r < 0)
1182                 return -errno;
1183
1184         if (no < 0)
1185                 return -EIO;
1186
1187         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1188                 return -ENOMEM;
1189
1190         return 0;
1191 }
1192
1193 int openpt_allocate_in_namespace(pid_t pid, int flags, char **ret_slave) {
1194         _cleanup_close_ int pidnsfd = -EBADF, mntnsfd = -EBADF, usernsfd = -EBADF, rootfd = -EBADF, fd = -EBADF;
1195         _cleanup_close_pair_ int pair[2] = EBADF_PAIR;
1196         pid_t child;
1197         int r;
1198
1199         assert(pid > 0);
1200
1201         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1202         if (r < 0)
1203                 return r;
1204
1205         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1206                 return -errno;
1207
1208         r = namespace_fork("(sd-openptns)", "(sd-openpt)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGKILL,
1209                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1210         if (r < 0)
1211                 return r;
1212         if (r == 0) {
1213                 pair[0] = safe_close(pair[0]);
1214
1215                 fd = openpt_allocate(flags, NULL);
1216                 if (fd < 0)
1217                         _exit(EXIT_FAILURE);
1218
1219                 if (send_one_fd(pair[1], fd, 0) < 0)
1220                         _exit(EXIT_FAILURE);
1221
1222                 _exit(EXIT_SUCCESS);
1223         }
1224
1225         pair[1] = safe_close(pair[1]);
1226
1227         r = wait_for_terminate_and_check("(sd-openptns)", child, 0);
1228         if (r < 0)
1229                 return r;
1230         if (r != EXIT_SUCCESS)
1231                 return -EIO;
1232
1233         fd = receive_one_fd(pair[0], 0);
1234         if (fd < 0)
1235                 return fd;
1236
1237         if (ret_slave) {
1238                 r = ptsname_namespace(fd, ret_slave);
1239                 if (r < 0)
1240                         return r;
1241         }
1242
1243         return TAKE_FD(fd);
1244 }
1245
1246 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1247         _cleanup_close_ int pidnsfd = -EBADF, mntnsfd = -EBADF, usernsfd = -EBADF, rootfd = -EBADF;
1248         _cleanup_close_pair_ int pair[2] = EBADF_PAIR;
1249         pid_t child;
1250         int r;
1251
1252         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1253         if (r < 0)
1254                 return r;
1255
1256         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1257                 return -errno;
1258
1259         r = namespace_fork("(sd-terminalns)", "(sd-terminal)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGKILL,
1260                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1261         if (r < 0)
1262                 return r;
1263         if (r == 0) {
1264                 int master;
1265
1266                 pair[0] = safe_close(pair[0]);
1267
1268                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1269                 if (master < 0)
1270                         _exit(EXIT_FAILURE);
1271
1272                 if (send_one_fd(pair[1], master, 0) < 0)
1273                         _exit(EXIT_FAILURE);
1274
1275                 _exit(EXIT_SUCCESS);
1276         }
1277
1278         pair[1] = safe_close(pair[1]);
1279
1280         r = wait_for_terminate_and_check("(sd-terminalns)", child, 0);
1281         if (r < 0)
1282                 return r;
1283         if (r != EXIT_SUCCESS)
1284                 return -EIO;
1285
1286         return receive_one_fd(pair[0], 0);
1287 }
1288
1289 static bool on_dev_null(void) {
1290         struct stat dst, ost, est;
1291
1292         if (cached_on_dev_null >= 0)
1293                 return cached_on_dev_null;
1294
1295         if (stat("/dev/null", &dst) < 0 || fstat(STDOUT_FILENO, &ost) < 0 || fstat(STDERR_FILENO, &est) < 0)
1296                 cached_on_dev_null = false;
1297         else
1298                 cached_on_dev_null = stat_inode_same(&dst, &ost) && stat_inode_same(&dst, &est);
1299
1300         return cached_on_dev_null;
1301 }
1302
1303 static bool getenv_terminal_is_dumb(void) {
1304         const char *e;
1305
1306         e = getenv("TERM");
1307         if (!e)
1308                 return true;
1309
1310         return streq(e, "dumb");
1311 }
1312
1313 bool terminal_is_dumb(void) {
1314         if (!on_tty() && !on_dev_null())
1315                 return true;
1316
1317         return getenv_terminal_is_dumb();
1318 }
1319
1320 static ColorMode parse_systemd_colors(void) {
1321         const char *e;
1322         int r;
1323
1324         e = getenv("SYSTEMD_COLORS");
1325         if (!e)
1326                 return _COLOR_INVALID;
1327         if (streq(e, "16"))
1328                 return COLOR_16;
1329         if (streq(e, "256"))
1330                 return COLOR_256;
1331         r = parse_boolean(e);
1332         if (r >= 0)
1333                 return r > 0 ? COLOR_ON : COLOR_OFF;
1334         return _COLOR_INVALID;
1335 }
1336
1337 ColorMode get_color_mode(void) {
1338
1339         /* Returns the mode used to choose output colors. The possible modes are COLOR_OFF for no colors,
1340          * COLOR_16 for only the base 16 ANSI colors, COLOR_256 for more colors and COLOR_ON for unrestricted
1341          * color output. For that we check $SYSTEMD_COLORS first (which is the explicit way to
1342          * change the mode). If that didn't work we turn colors off unless we are on a TTY. And if we are on a TTY
1343          * we turn it off if $TERM is set to "dumb". There's one special tweak though: if we are PID 1 then we do not
1344          * check whether we are connected to a TTY, because we don't keep /dev/console open continuously due to fear
1345          * of SAK, and hence things are a bit weird. */
1346         ColorMode m;
1347
1348         if (cached_color_mode < 0) {
1349                 m = parse_systemd_colors();
1350                 if (m >= 0)
1351                         cached_color_mode = m;
1352                 else if (getenv("NO_COLOR"))
1353                         /* We only check for the presence of the variable; value is ignored. */
1354                         cached_color_mode = COLOR_OFF;
1355
1356                 else if (getpid_cached() == 1) {
1357                         /* PID1 outputs to the console without holding it open all the time.
1358                          *
1359                          * Note that the Linux console can only display 16 colors. We still enable 256 color
1360                          * mode even for PID1 output though (which typically goes to the Linux console),
1361                          * since the Linux console is able to parse the 256 color sequences and automatically
1362                          * map them to the closest color in the 16 color palette (since kernel 3.16). Doing
1363                          * 256 colors is nice for people who invoke systemd in a container or via a serial
1364                          * link or such, and use a true 256 color terminal to do so. */
1365                         if (getenv_terminal_is_dumb())
1366                                 cached_color_mode = COLOR_OFF;
1367                 } else {
1368                         if (terminal_is_dumb())
1369                                 cached_color_mode = COLOR_OFF;
1370                 }
1371
1372                 if (cached_color_mode < 0) {
1373                         /* We failed to figure out any reason to *disable* colors.
1374                          * Let's see how many colors we shall use. */
1375                         if (STRPTR_IN_SET(getenv("COLORTERM"),
1376                                           "truecolor",
1377                                           "24bit"))
1378                                 cached_color_mode = COLOR_24BIT;
1379                         else
1380                                 cached_color_mode = COLOR_256;
1381                 }
1382         }
1383
1384         return cached_color_mode;
1385 }
1386
1387 bool dev_console_colors_enabled(void) {
1388         _cleanup_free_ char *s = NULL;
1389         ColorMode m;
1390
1391         /* Returns true if we assume that color is supported on /dev/console.
1392          *
1393          * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
1394          * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
1395          * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
1396          * colors_enabled() operates. */
1397
1398         m = parse_systemd_colors();
1399         if (m >= 0)
1400                 return m;
1401
1402         if (getenv("NO_COLOR"))
1403                 return false;
1404
1405         if (getenv_for_pid(1, "TERM", &s) <= 0)
1406                 (void) proc_cmdline_get_key("TERM", 0, &s);
1407
1408         return !streq_ptr(s, "dumb");
1409 }
1410
1411 bool underline_enabled(void) {
1412
1413         if (cached_underline_enabled < 0) {
1414
1415                 /* The Linux console doesn't support underlining, turn it off, but only there. */
1416
1417                 if (colors_enabled())
1418                         cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
1419                 else
1420                         cached_underline_enabled = false;
1421         }
1422
1423         return cached_underline_enabled;
1424 }
1425
1426 int vt_default_utf8(void) {
1427         _cleanup_free_ char *b = NULL;
1428         int r;
1429
1430         /* Read the default VT UTF8 setting from the kernel */
1431
1432         r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
1433         if (r < 0)
1434                 return r;
1435
1436         return parse_boolean(b);
1437 }
1438
1439 int vt_reset_keyboard(int fd) {
1440         int kb;
1441
1442         /* If we can't read the default, then default to unicode. It's 2017 after all. */
1443         kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
1444
1445         return RET_NERRNO(ioctl(fd, KDSKBMODE, kb));
1446 }
1447
1448 int vt_restore(int fd) {
1449         static const struct vt_mode mode = {
1450                 .mode = VT_AUTO,
1451         };
1452         int r, q = 0;
1453
1454         if (isatty(fd) < 1)
1455                 return log_debug_errno(errno, "Asked to restore the VT for an fd that does not refer to a terminal: %m");
1456
1457         if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
1458                 q = log_debug_errno(errno, "Failed to set VT in text mode, ignoring: %m");
1459
1460         r = vt_reset_keyboard(fd);
1461         if (r < 0) {
1462                 log_debug_errno(r, "Failed to reset keyboard mode, ignoring: %m");
1463                 if (q >= 0)
1464                         q = r;
1465         }
1466
1467         if (ioctl(fd, VT_SETMODE, &mode) < 0) {
1468                 log_debug_errno(errno, "Failed to set VT_AUTO mode, ignoring: %m");
1469                 if (q >= 0)
1470                         q = -errno;
1471         }
1472
1473         r = fchmod_and_chown(fd, TTY_MODE, 0, GID_INVALID);
1474         if (r < 0) {
1475                 log_debug_errno(r, "Failed to chmod()/chown() VT, ignoring: %m");
1476                 if (q >= 0)
1477                         q = r;
1478         }
1479
1480         return q;
1481 }
1482
1483 int vt_release(int fd, bool restore) {
1484         assert(fd >= 0);
1485
1486         /* This function releases the VT by acknowledging the VT-switch signal
1487          * sent by the kernel and optionally reset the VT in text and auto
1488          * VT-switching modes. */
1489
1490         if (isatty(fd) < 1)
1491                 return log_debug_errno(errno, "Asked to release the VT for an fd that does not refer to a terminal: %m");
1492
1493         if (ioctl(fd, VT_RELDISP, 1) < 0)
1494                 return -errno;
1495
1496         if (restore)
1497                 return vt_restore(fd);
1498
1499         return 0;
1500 }
1501
1502 void get_log_colors(int priority, const char **on, const char **off, const char **highlight) {
1503         /* Note that this will initialize output variables only when there's something to output.
1504          * The caller must pre-initialize to "" or NULL as appropriate. */
1505
1506         if (priority <= LOG_ERR) {
1507                 if (on)
1508                         *on = ansi_highlight_red();
1509                 if (off)
1510                         *off = ansi_normal();
1511                 if (highlight)
1512                         *highlight = ansi_highlight();
1513
1514         } else if (priority <= LOG_WARNING) {
1515                 if (on)
1516                         *on = ansi_highlight_yellow();
1517                 if (off)
1518                         *off = ansi_normal();
1519                 if (highlight)
1520                         *highlight = ansi_highlight();
1521
1522         } else if (priority <= LOG_NOTICE) {
1523                 if (on)
1524                         *on = ansi_highlight();
1525                 if (off)
1526                         *off = ansi_normal();
1527                 if (highlight)
1528                         *highlight = ansi_highlight_red();
1529
1530         } else if (priority >= LOG_DEBUG) {
1531                 if (on)
1532                         *on = ansi_grey();
1533                 if (off)
1534                         *off = ansi_normal();
1535                 if (highlight)
1536                         *highlight = ansi_highlight_red();
1537         }
1538 }
1539
1540 int set_terminal_cursor_position(int fd, unsigned int row, unsigned int column) {
1541         int r;
1542         char cursor_position[STRLEN("\x1B[") + DECIMAL_STR_MAX(int) * 2 + STRLEN(";H") + 1];
1543
1544         assert(fd >= 0);
1545
1546         xsprintf(cursor_position, "\x1B[%u;%uH", row, column);
1547
1548         r = loop_write(fd, cursor_position, SIZE_MAX);
1549         if (r < 0)
1550                 return log_warning_errno(r, "Failed to set cursor position, ignoring: %m");
1551
1552         return 0;
1553 }