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         int r;
 204
 205         assert(ret);
 206         assert(text);
 207
 208         for (;;) {
 209                 _cleanup_free_ char *line = NULL;
 210                 va_list ap;
 211
 212                 if (colors_enabled())
 213                         fputs(ANSI_HIGHLIGHT, stdout);
 214
 215                 va_start(ap, text);
 216                 vprintf(text, ap);
 217                 va_end(ap);
 218
 219                 if (colors_enabled())
 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                 if (!isempty(line)) {
 231                         *ret = TAKE_PTR(line);
 232                         return 0;
 233                 }
 234         }
 235 }
 236
 237 int reset_terminal_fd(int fd, bool switch_to_text) {
 238         struct termios termios;
 239         int r = 0;
 240
 241         /* Set terminal to some sane defaults */
 242
 243         assert(fd >= 0);
 244
 245         /* We leave locked terminal attributes untouched, so that
 246          * Plymouth may set whatever it wants to set, and we don't
 247          * interfere with that. */
 248
 249         /* Disable exclusive mode, just in case */
 250         (void) ioctl(fd, TIOCNXCL);
 251
 252         /* Switch to text mode */
 253         if (switch_to_text)
 254                 (void) ioctl(fd, KDSETMODE, KD_TEXT);
 255
 256         /* Set default keyboard mode */
 257         (void) vt_reset_keyboard(fd);
 258
 259         if (tcgetattr(fd, &termios) < 0) {
 260                 r = -errno;
 261                 goto finish;
 262         }
 263
 264         /* We only reset the stuff that matters to the software. How
 265          * hardware is set up we don't touch assuming that somebody
 266          * else will do that for us */
 267
 268         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 269         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 270         termios.c_oflag |= ONLCR;
 271         termios.c_cflag |= CREAD;
 272         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 273
 274         termios.c_cc[VINTR]    =   03;  /* ^C */
 275         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 276         termios.c_cc[VERASE]   = 0177;
 277         termios.c_cc[VKILL]    =  025;  /* ^X */
 278         termios.c_cc[VEOF]     =   04;  /* ^D */
 279         termios.c_cc[VSTART]   =  021;  /* ^Q */
 280         termios.c_cc[VSTOP]    =  023;  /* ^S */
 281         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 282         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 283         termios.c_cc[VWERASE]  =  027;  /* ^W */
 284         termios.c_cc[VREPRINT] =  022;  /* ^R */
 285         termios.c_cc[VEOL]     =    0;
 286         termios.c_cc[VEOL2]    =    0;
 287
 288         termios.c_cc[VTIME]  = 0;
 289         termios.c_cc[VMIN]   = 1;
 290
 291         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 292                 r = -errno;
 293
 294 finish:
 295         /* Just in case, flush all crap out */
 296         (void) tcflush(fd, TCIOFLUSH);
 297
 298         return r;
 299 }
 300
 301 int reset_terminal(const char *name) {
 302         _cleanup_close_ int fd = -1;
 303
 304         /* We open the terminal with O_NONBLOCK here, to ensure we
 305          * don't block on carrier if this is a terminal with carrier
 306          * configured. */
 307
 308         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 309         if (fd < 0)
 310                 return fd;
 311
 312         return reset_terminal_fd(fd, true);
 313 }
 314
 315 int open_terminal(const char *name, int mode) {
 316         unsigned c = 0;
 317         int fd;
 318
 319         /*
 320          * If a TTY is in the process of being closed opening it might
 321          * cause EIO. This is horribly awful, but unlikely to be
 322          * changed in the kernel. Hence we work around this problem by
 323          * retrying a couple of times.
 324          *
 325          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 326          */
 327
 328         if (mode & O_CREAT)
 329                 return -EINVAL;
 330
 331         for (;;) {
 332                 fd = open(name, mode, 0);
 333                 if (fd >= 0)
 334                         break;
 335
 336                 if (errno != EIO)
 337                         return -errno;
 338
 339                 /* Max 1s in total */
 340                 if (c >= 20)
 341                         return -errno;
 342
 343                 usleep(50 * USEC_PER_MSEC);
 344                 c++;
 345         }
 346
 347         if (isatty(fd) <= 0) {
 348                 safe_close(fd);
 349                 return -ENOTTY;
 350         }
 351
 352         return fd;
 353 }
 354
 355 int acquire_terminal(
 356                 const char *name,
 357                 AcquireTerminalFlags flags,
 358                 usec_t timeout) {
 359
 360         _cleanup_close_ int notify = -1, fd = -1;
 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 = ioctl(fd, TIOCSCTTY,
 412                           (flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_FORCE) < 0 ? -errno : 0;
 413
 414                 /* Reset signal handler to old value */
 415                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 416
 417                 /* Success? Exit the loop now! */
 418                 if (r >= 0)
 419                         break;
 420
 421                 /* Any failure besides -EPERM? Fail, regardless of the mode. */
 422                 if (r != -EPERM)
 423                         return r;
 424
 425                 if (flags & ACQUIRE_TERMINAL_PERMISSIVE) /* If we are in permissive mode, then EPERM is fine, turn this
 426                                                           * into a success. Note that EPERM is also returned if we
 427                                                           * already are the owner of the TTY. */
 428                         break;
 429
 430                 if (flags != ACQUIRE_TERMINAL_WAIT) /* If we are in TRY or FORCE mode, then propagate EPERM as EPERM */
 431                         return r;
 432
 433                 assert(notify >= 0);
 434                 assert(wd >= 0);
 435
 436                 for (;;) {
 437                         union inotify_event_buffer buffer;
 438                         struct inotify_event *e;
 439                         ssize_t l;
 440
 441                         if (timeout != USEC_INFINITY) {
 442                                 usec_t n;
 443
 444                                 assert(ts != USEC_INFINITY);
 445
 446                                 n = now(CLOCK_MONOTONIC);
 447                                 if (ts + timeout < n)
 448                                         return -ETIMEDOUT;
 449
 450                                 r = fd_wait_for_event(notify, POLLIN, ts + timeout - n);
 451                                 if (r < 0)
 452                                         return r;
 453                                 if (r == 0)
 454                                         return -ETIMEDOUT;
 455                         }
 456
 457                         l = read(notify, &buffer, sizeof(buffer));
 458                         if (l < 0) {
 459                                 if (IN_SET(errno, EINTR, EAGAIN))
 460                                         continue;
 461
 462                                 return -errno;
 463                         }
 464
 465                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 466                                 if (e->mask & IN_Q_OVERFLOW) /* If we hit an inotify queue overflow, simply check if the terminal is up for grabs now. */
 467                                         break;
 468
 469                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) /* Safety checks */
 470                                         return -EIO;
 471                         }
 472
 473                         break;
 474                 }
 475
 476                 /* We close the tty fd here since if the old session ended our handle will be dead. It's important that
 477                  * we do this after sleeping, so that we don't enter an endless loop. */
 478                 fd = safe_close(fd);
 479         }
 480
 481         return TAKE_FD(fd);
 482 }
 483
 484 int release_terminal(void) {
 485         static const struct sigaction sa_new = {
 486                 .sa_handler = SIG_IGN,
 487                 .sa_flags = SA_RESTART,
 488         };
 489
 490         _cleanup_close_ int fd = -1;
 491         struct sigaction sa_old;
 492         int r;
 493
 494         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 495         if (fd < 0)
 496                 return -errno;
 497
 498         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 499          * by our own TIOCNOTTY */
 500         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 501
 502         r = ioctl(fd, TIOCNOTTY) < 0 ? -errno : 0;
 503
 504         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 505
 506         return r;
 507 }
 508
 509 int terminal_vhangup_fd(int fd) {
 510         assert(fd >= 0);
 511
 512         if (ioctl(fd, TIOCVHANGUP) < 0)
 513                 return -errno;
 514
 515         return 0;
 516 }
 517
 518 int terminal_vhangup(const char *name) {
 519         _cleanup_close_ int fd;
 520
 521         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 522         if (fd < 0)
 523                 return fd;
 524
 525         return terminal_vhangup_fd(fd);
 526 }
 527
 528 int vt_disallocate(const char *name) {
 529         _cleanup_close_ int fd = -1;
 530         const char *e, *n;
 531         unsigned u;
 532         int r;
 533
 534         /* Deallocate the VT if possible. If not possible
 535          * (i.e. because it is the active one), at least clear it
 536          * entirely (including the scrollback buffer) */
 537
 538         e = path_startswith(name, "/dev/");
 539         if (!e)
 540                 return -EINVAL;
 541
 542         if (!tty_is_vc(name)) {
 543                 /* So this is not a VT. I guess we cannot deallocate
 544                  * it then. But let's at least clear the screen */
 545
 546                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 547                 if (fd < 0)
 548                         return fd;
 549
 550                 loop_write(fd,
 551                            "\033[r"    /* clear scrolling region */
 552                            "\033[H"    /* move home */
 553                            "\033[2J",  /* clear screen */
 554                            10, false);
 555                 return 0;
 556         }
 557
 558         n = startswith(e, "tty");
 559         if (!n)
 560                 return -EINVAL;
 561
 562         r = safe_atou(n, &u);
 563         if (r < 0)
 564                 return r;
 565
 566         if (u <= 0)
 567                 return -EINVAL;
 568
 569         /* Try to deallocate */
 570         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 571         if (fd < 0)
 572                 return fd;
 573
 574         r = ioctl(fd, VT_DISALLOCATE, u);
 575         fd = safe_close(fd);
 576
 577         if (r >= 0)
 578                 return 0;
 579
 580         if (errno != EBUSY)
 581                 return -errno;
 582
 583         /* Couldn't deallocate, so let's clear it fully with
 584          * scrollback */
 585         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 586         if (fd < 0)
 587                 return fd;
 588
 589         loop_write(fd,
 590                    "\033[r"   /* clear scrolling region */
 591                    "\033[H"   /* move home */
 592                    "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 593                    10, false);
 594         return 0;
 595 }
 596
 597 int make_console_stdio(void) {
 598         int fd, r;
 599
 600         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 601
 602         fd = acquire_terminal("/dev/console", ACQUIRE_TERMINAL_FORCE|ACQUIRE_TERMINAL_PERMISSIVE, USEC_INFINITY);
 603         if (fd < 0)
 604                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 605
 606         r = reset_terminal_fd(fd, true);
 607         if (r < 0)
 608                 log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 609
 610         r = rearrange_stdio(fd, fd, fd); /* This invalidates 'fd' both on success and on failure. */
 611         if (r < 0)
 612                 return log_error_errno(r, "Failed to make terminal stdin/stdout/stderr: %m");
 613
 614         reset_terminal_feature_caches();
 615
 616         return 0;
 617 }
 618
 619 bool tty_is_vc(const char *tty) {
 620         assert(tty);
 621
 622         return vtnr_from_tty(tty) >= 0;
 623 }
 624
 625 bool tty_is_console(const char *tty) {
 626         assert(tty);
 627
 628         return streq(skip_dev_prefix(tty), "console");
 629 }
 630
 631 int vtnr_from_tty(const char *tty) {
 632         int i, r;
 633
 634         assert(tty);
 635
 636         tty = skip_dev_prefix(tty);
 637
 638         if (!startswith(tty, "tty") )
 639                 return -EINVAL;
 640
 641         if (tty[3] < '0' || tty[3] > '9')
 642                 return -EINVAL;
 643
 644         r = safe_atoi(tty+3, &i);
 645         if (r < 0)
 646                 return r;
 647
 648         if (i < 0 || i > 63)
 649                 return -EINVAL;
 650
 651         return i;
 652 }
 653
 654  int resolve_dev_console(char **ret) {
 655         _cleanup_free_ char *active = NULL;
 656         char *tty;
 657         int r;
 658
 659         assert(ret);
 660
 661         /* Resolve where /dev/console is pointing to, if /sys is actually ours (i.e. not read-only-mounted which is a
 662          * sign for container setups) */
 663
 664         if (path_is_read_only_fs("/sys") > 0)
 665                 return -ENOMEDIUM;
 666
 667         r = read_one_line_file("/sys/class/tty/console/active", &active);
 668         if (r < 0)
 669                 return r;
 670
 671         /* If multiple log outputs are configured the last one is what /dev/console points to */
 672         tty = strrchr(active, ' ');
 673         if (tty)
 674                 tty++;
 675         else
 676                 tty = active;
 677
 678         if (streq(tty, "tty0")) {
 679                 active = mfree(active);
 680
 681                 /* Get the active VC (e.g. tty1) */
 682                 r = read_one_line_file("/sys/class/tty/tty0/active", &active);
 683                 if (r < 0)
 684                         return r;
 685
 686                 tty = active;
 687         }
 688
 689         if (tty == active)
 690                 *ret = TAKE_PTR(active);
 691         else {
 692                 char *tmp;
 693
 694                 tmp = strdup(tty);
 695                 if (!tmp)
 696                         return -ENOMEM;
 697
 698                 *ret = tmp;
 699         }
 700
 701         return 0;
 702 }
 703
 704 int get_kernel_consoles(char ***ret) {
 705         _cleanup_strv_free_ char **l = NULL;
 706         _cleanup_free_ char *line = NULL;
 707         const char *p;
 708         int r;
 709
 710         assert(ret);
 711
 712         /* If /sys is mounted read-only this means we are running in some kind of container environment. In that
 713          * case /sys would reflect the host system, not us, hence ignore the data we can read from it. */
 714         if (path_is_read_only_fs("/sys") > 0)
 715                 goto fallback;
 716
 717         r = read_one_line_file("/sys/class/tty/console/active", &line);
 718         if (r < 0)
 719                 return r;
 720
 721         p = line;
 722         for (;;) {
 723                 _cleanup_free_ char *tty = NULL, *path = NULL;
 724
 725                 r = extract_first_word(&p, &tty, NULL, 0);
 726                 if (r < 0)
 727                         return r;
 728                 if (r == 0)
 729                         break;
 730
 731                 if (streq(tty, "tty0")) {
 732                         tty = mfree(tty);
 733                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 734                         if (r < 0)
 735                                 return r;
 736                 }
 737
 738                 path = path_join("/dev", tty);
 739                 if (!path)
 740                         return -ENOMEM;
 741
 742                 if (access(path, F_OK) < 0) {
 743                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 744                         continue;
 745                 }
 746
 747                 r = strv_consume(&l, TAKE_PTR(path));
 748                 if (r < 0)
 749                         return r;
 750         }
 751
 752         if (strv_isempty(l)) {
 753                 log_debug("No devices found for system console");
 754                 goto fallback;
 755         }
 756
 757         *ret = TAKE_PTR(l);
 758
 759         return 0;
 760
 761 fallback:
 762         r = strv_extend(&l, "/dev/console");
 763         if (r < 0)
 764                 return r;
 765
 766         *ret = TAKE_PTR(l);
 767
 768         return 0;
 769 }
 770
 771 bool tty_is_vc_resolve(const char *tty) {
 772         _cleanup_free_ char *resolved = NULL;
 773
 774         assert(tty);
 775
 776         tty = skip_dev_prefix(tty);
 777
 778         if (streq(tty, "console")) {
 779                 if (resolve_dev_console(&resolved) < 0)
 780                         return false;
 781
 782                 tty = resolved;
 783         }
 784
 785         return tty_is_vc(tty);
 786 }
 787
 788 const char *default_term_for_tty(const char *tty) {
 789         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 790 }
 791
 792 int fd_columns(int fd) {
 793         struct winsize ws = {};
 794
 795         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 796                 return -errno;
 797
 798         if (ws.ws_col <= 0)
 799                 return -EIO;
 800
 801         return ws.ws_col;
 802 }
 803
 804 unsigned columns(void) {
 805         const char *e;
 806         int c;
 807
 808         if (cached_columns > 0)
 809                 return cached_columns;
 810
 811         c = 0;
 812         e = getenv("COLUMNS");
 813         if (e)
 814                 (void) safe_atoi(e, &c);
 815
 816         if (c <= 0 || c > USHRT_MAX) {
 817                 c = fd_columns(STDOUT_FILENO);
 818                 if (c <= 0)
 819                         c = 80;
 820         }
 821
 822         cached_columns = c;
 823         return cached_columns;
 824 }
 825
 826 int fd_lines(int fd) {
 827         struct winsize ws = {};
 828
 829         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 830                 return -errno;
 831
 832         if (ws.ws_row <= 0)
 833                 return -EIO;
 834
 835         return ws.ws_row;
 836 }
 837
 838 unsigned lines(void) {
 839         const char *e;
 840         int l;
 841
 842         if (cached_lines > 0)
 843                 return cached_lines;
 844
 845         l = 0;
 846         e = getenv("LINES");
 847         if (e)
 848                 (void) safe_atoi(e, &l);
 849
 850         if (l <= 0 || l > USHRT_MAX) {
 851                 l = fd_lines(STDOUT_FILENO);
 852                 if (l <= 0)
 853                         l = 24;
 854         }
 855
 856         cached_lines = l;
 857         return cached_lines;
 858 }
 859
 860 /* intended to be used as a SIGWINCH sighandler */
 861 void columns_lines_cache_reset(int signum) {
 862         cached_columns = 0;
 863         cached_lines = 0;
 864 }
 865
 866 void reset_terminal_feature_caches(void) {
 867         cached_columns = 0;
 868         cached_lines = 0;
 869
 870         cached_colors_enabled = -1;
 871         cached_underline_enabled = -1;
 872         cached_on_tty = -1;
 873 }
 874
 875 bool on_tty(void) {
 876
 877         /* We check both stdout and stderr, so that situations where pipes on the shell are used are reliably
 878          * recognized, regardless if only the output or the errors are piped to some place. Since on_tty() is generally
 879          * used to default to a safer, non-interactive, non-color mode of operation it's probably good to be defensive
 880          * here, and check for both. Note that we don't check for STDIN_FILENO, because it should fine to use fancy
 881          * terminal functionality when outputting stuff, even if the input is piped to us. */
 882
 883         if (cached_on_tty < 0)
 884                 cached_on_tty =
 885                         isatty(STDOUT_FILENO) > 0 &&
 886                         isatty(STDERR_FILENO) > 0;
 887
 888         return cached_on_tty;
 889 }
 890
 891 int getttyname_malloc(int fd, char **ret) {
 892         char path[PATH_MAX], *c; /* PATH_MAX is counted *with* the trailing NUL byte */
 893         int r;
 894
 895         assert(fd >= 0);
 896         assert(ret);
 897
 898         r = ttyname_r(fd, path, sizeof path); /* positive error */
 899         assert(r >= 0);
 900         if (r == ERANGE)
 901                 return -ENAMETOOLONG;
 902         if (r > 0)
 903                 return -r;
 904
 905         c = strdup(skip_dev_prefix(path));
 906         if (!c)
 907                 return -ENOMEM;
 908
 909         *ret = c;
 910         return 0;
 911 }
 912
 913 int getttyname_harder(int fd, char **ret) {
 914         _cleanup_free_ char *s = NULL;
 915         int r;
 916
 917         r = getttyname_malloc(fd, &s);
 918         if (r < 0)
 919                 return r;
 920
 921         if (streq(s, "tty"))
 922                 return get_ctty(0, NULL, ret);
 923
 924         *ret = TAKE_PTR(s);
 925         return 0;
 926 }
 927
 928 int get_ctty_devnr(pid_t pid, dev_t *d) {
 929         int r;
 930         _cleanup_free_ char *line = NULL;
 931         const char *p;
 932         unsigned long ttynr;
 933
 934         assert(pid >= 0);
 935
 936         p = procfs_file_alloca(pid, "stat");
 937         r = read_one_line_file(p, &line);
 938         if (r < 0)
 939                 return r;
 940
 941         p = strrchr(line, ')');
 942         if (!p)
 943                 return -EIO;
 944
 945         p++;
 946
 947         if (sscanf(p, " "
 948                    "%*c "  /* state */
 949                    "%*d "  /* ppid */
 950                    "%*d "  /* pgrp */
 951                    "%*d "  /* session */
 952                    "%lu ", /* ttynr */
 953                    &ttynr) != 1)
 954                 return -EIO;
 955
 956         if (major(ttynr) == 0 && minor(ttynr) == 0)
 957                 return -ENXIO;
 958
 959         if (d)
 960                 *d = (dev_t) ttynr;
 961
 962         return 0;
 963 }
 964
 965 int get_ctty(pid_t pid, dev_t *ret_devnr, char **ret) {
 966         _cleanup_free_ char *fn = NULL, *b = NULL;
 967         dev_t devnr;
 968         int r;
 969
 970         r = get_ctty_devnr(pid, &devnr);
 971         if (r < 0)
 972                 return r;
 973
 974         r = device_path_make_canonical(S_IFCHR, devnr, &fn);
 975         if (r < 0) {
 976                 if (r != -ENOENT) /* No symlink for this in /dev/char/? */
 977                         return r;
 978
 979                 if (major(devnr) == 136) {
 980                         /* This is an ugly hack: PTY devices are not listed in /dev/char/, as they don't follow the
 981                          * Linux device model. This means we have no nice way to match them up against their actual
 982                          * device node. Let's hence do the check by the fixed, assigned major number. Normally we try
 983                          * to avoid such fixed major/minor matches, but there appears to nother nice way to handle
 984                          * this. */
 985
 986                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
 987                                 return -ENOMEM;
 988                 } else {
 989                         /* Probably something similar to the ptys which have no symlink in /dev/char/. Let's return
 990                          * something vaguely useful. */
 991
 992                         r = device_path_make_major_minor(S_IFCHR, devnr, &fn);
 993                         if (r < 0)
 994                                 return r;
 995                 }
 996         }
 997
 998         if (!b) {
 999                 const char *w;
1000
1001                 w = path_startswith(fn, "/dev/");
1002                 if (w) {
1003                         b = strdup(w);
1004                         if (!b)
1005                                 return -ENOMEM;
1006                 } else
1007                         b = TAKE_PTR(fn);
1008         }
1009
1010         if (ret)
1011                 *ret = TAKE_PTR(b);
1012
1013         if (ret_devnr)
1014                 *ret_devnr = devnr;
1015
1016         return 0;
1017 }
1018
1019 int ptsname_malloc(int fd, char **ret) {
1020         size_t l = 100;
1021
1022         assert(fd >= 0);
1023         assert(ret);
1024
1025         for (;;) {
1026                 char *c;
1027
1028                 c = new(char, l);
1029                 if (!c)
1030                         return -ENOMEM;
1031
1032                 if (ptsname_r(fd, c, l) == 0) {
1033                         *ret = c;
1034                         return 0;
1035                 }
1036                 if (errno != ERANGE) {
1037                         free(c);
1038                         return -errno;
1039                 }
1040
1041                 free(c);
1042
1043                 if (l > SIZE_MAX / 2)
1044                         return -ENOMEM;
1045
1046                 l *= 2;
1047         }
1048 }
1049
1050 int openpt_allocate(int flags, char **ret_slave) {
1051         _cleanup_close_ int fd = -1;
1052         _cleanup_free_ char *p = NULL;
1053         int r;
1054
1055         fd = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1056         if (fd < 0)
1057                 return -errno;
1058
1059         if (ret_slave) {
1060                 r = ptsname_malloc(fd, &p);
1061                 if (r < 0)
1062                         return r;
1063
1064                 if (!path_startswith(p, "/dev/pts/"))
1065                         return -EINVAL;
1066         }
1067
1068         if (unlockpt(fd) < 0)
1069                 return -errno;
1070
1071         if (ret_slave)
1072                 *ret_slave = TAKE_PTR(p);
1073
1074         return TAKE_FD(fd);
1075 }
1076
1077 static int ptsname_namespace(int pty, char **ret) {
1078         int no = -1, r;
1079
1080         /* Like ptsname(), but doesn't assume that the path is
1081          * accessible in the local namespace. */
1082
1083         r = ioctl(pty, TIOCGPTN, &no);
1084         if (r < 0)
1085                 return -errno;
1086
1087         if (no < 0)
1088                 return -EIO;
1089
1090         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1091                 return -ENOMEM;
1092
1093         return 0;
1094 }
1095
1096 int openpt_allocate_in_namespace(pid_t pid, int flags, char **ret_slave) {
1097         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1, fd = -1;
1098         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1099         pid_t child;
1100         int r;
1101
1102         assert(pid > 0);
1103
1104         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1105         if (r < 0)
1106                 return r;
1107
1108         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1109                 return -errno;
1110
1111         r = namespace_fork("(sd-openptns)", "(sd-openpt)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
1112                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1113         if (r < 0)
1114                 return r;
1115         if (r == 0) {
1116                 pair[0] = safe_close(pair[0]);
1117
1118                 fd = openpt_allocate(flags, NULL);
1119                 if (fd < 0)
1120                         _exit(EXIT_FAILURE);
1121
1122                 if (send_one_fd(pair[1], fd, 0) < 0)
1123                         _exit(EXIT_FAILURE);
1124
1125                 _exit(EXIT_SUCCESS);
1126         }
1127
1128         pair[1] = safe_close(pair[1]);
1129
1130         r = wait_for_terminate_and_check("(sd-openptns)", child, 0);
1131         if (r < 0)
1132                 return r;
1133         if (r != EXIT_SUCCESS)
1134                 return -EIO;
1135
1136         fd = receive_one_fd(pair[0], 0);
1137         if (fd < 0)
1138                 return fd;
1139
1140         if (ret_slave) {
1141                 r = ptsname_namespace(fd, ret_slave);
1142                 if (r < 0)
1143                         return r;
1144         }
1145
1146         return TAKE_FD(fd);
1147 }
1148
1149 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1150         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1151         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1152         pid_t child;
1153         int r;
1154
1155         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1156         if (r < 0)
1157                 return r;
1158
1159         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1160                 return -errno;
1161
1162         r = namespace_fork("(sd-terminalns)", "(sd-terminal)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
1163                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1164         if (r < 0)
1165                 return r;
1166         if (r == 0) {
1167                 int master;
1168
1169                 pair[0] = safe_close(pair[0]);
1170
1171                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1172                 if (master < 0)
1173                         _exit(EXIT_FAILURE);
1174
1175                 if (send_one_fd(pair[1], master, 0) < 0)
1176                         _exit(EXIT_FAILURE);
1177
1178                 _exit(EXIT_SUCCESS);
1179         }
1180
1181         pair[1] = safe_close(pair[1]);
1182
1183         r = wait_for_terminate_and_check("(sd-terminalns)", child, 0);
1184         if (r < 0)
1185                 return r;
1186         if (r != EXIT_SUCCESS)
1187                 return -EIO;
1188
1189         return receive_one_fd(pair[0], 0);
1190 }
1191
1192 static bool getenv_terminal_is_dumb(void) {
1193         const char *e;
1194
1195         e = getenv("TERM");
1196         if (!e)
1197                 return true;
1198
1199         return streq(e, "dumb");
1200 }
1201
1202 bool terminal_is_dumb(void) {
1203         if (!on_tty())
1204                 return true;
1205
1206         return getenv_terminal_is_dumb();
1207 }
1208
1209 bool colors_enabled(void) {
1210
1211         /* Returns true if colors are considered supported on our stdout. For that we check $SYSTEMD_COLORS first
1212          * (which is the explicit way to turn colors on/off). If that didn't work we turn colors off unless we are on a
1213          * 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
1214          * we are PID 1 then we do not check whether we are connected to a TTY, because we don't keep /dev/console open
1215          * continuously due to fear of SAK, and hence things are a bit weird. */
1216
1217         if (cached_colors_enabled < 0) {
1218                 int val;
1219
1220                 val = getenv_bool("SYSTEMD_COLORS");
1221                 if (val >= 0)
1222                         cached_colors_enabled = val;
1223                 else if (getpid_cached() == 1)
1224                         /* PID1 outputs to the console without holding it open all the time */
1225                         cached_colors_enabled = !getenv_terminal_is_dumb();
1226                 else
1227                         cached_colors_enabled = !terminal_is_dumb();
1228         }
1229
1230         return cached_colors_enabled;
1231 }
1232
1233 bool dev_console_colors_enabled(void) {
1234         _cleanup_free_ char *s = NULL;
1235         int b;
1236
1237         /* Returns true if we assume that color is supported on /dev/console.
1238          *
1239          * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
1240          * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
1241          * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
1242          * colors_enabled() operates. */
1243
1244         b = getenv_bool("SYSTEMD_COLORS");
1245         if (b >= 0)
1246                 return b;
1247
1248         if (getenv_for_pid(1, "TERM", &s) <= 0)
1249                 (void) proc_cmdline_get_key("TERM", 0, &s);
1250
1251         return !streq_ptr(s, "dumb");
1252 }
1253
1254 bool underline_enabled(void) {
1255
1256         if (cached_underline_enabled < 0) {
1257
1258                 /* The Linux console doesn't support underlining, turn it off, but only there. */
1259
1260                 if (colors_enabled())
1261                         cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
1262                 else
1263                         cached_underline_enabled = false;
1264         }
1265
1266         return cached_underline_enabled;
1267 }
1268
1269 int vt_default_utf8(void) {
1270         _cleanup_free_ char *b = NULL;
1271         int r;
1272
1273         /* Read the default VT UTF8 setting from the kernel */
1274
1275         r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
1276         if (r < 0)
1277                 return r;
1278
1279         return parse_boolean(b);
1280 }
1281
1282 int vt_verify_kbmode(int fd) {
1283         int curr_mode;
1284
1285         /*
1286          * Make sure we only adjust consoles in K_XLATE or K_UNICODE mode.
1287          * Otherwise we would (likely) interfere with X11's processing of the
1288          * key events.
1289          *
1290          * http://lists.freedesktop.org/archives/systemd-devel/2013-February/008573.html
1291          */
1292
1293         if (ioctl(fd, KDGKBMODE, &curr_mode) < 0)
1294                 return -errno;
1295
1296         return IN_SET(curr_mode, K_XLATE, K_UNICODE) ? 0 : -EBUSY;
1297 }
1298
1299 int vt_reset_keyboard(int fd) {
1300         int kb, r;
1301
1302         /* If we can't read the default, then default to unicode. It's 2017 after all. */
1303         kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
1304
1305         r = vt_verify_kbmode(fd);
1306         if (r == -EBUSY) {
1307                 log_debug_errno(r, "Keyboard is not in XLATE or UNICODE mode, not resetting: %m");
1308                 return 0;
1309         } else if (r < 0)
1310                 return r;
1311
1312         if (ioctl(fd, KDSKBMODE, kb) < 0)
1313                 return -errno;
1314
1315         return 0;
1316 }
1317
1318 int vt_restore(int fd) {
1319         static const struct vt_mode mode = {
1320                 .mode = VT_AUTO,
1321         };
1322         int r, q = 0;
1323
1324         if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
1325                 q = log_debug_errno(errno, "Failed to set VT in text mode, ignoring: %m");
1326
1327         r = vt_reset_keyboard(fd);
1328         if (r < 0) {
1329                 log_debug_errno(r, "Failed to reset keyboard mode, ignoring: %m");
1330                 if (q >= 0)
1331                         q = r;
1332         }
1333
1334         if (ioctl(fd, VT_SETMODE, &mode) < 0) {
1335                 log_debug_errno(errno, "Failed to set VT_AUTO mode, ignoring: %m");
1336                 if (q >= 0)
1337                         q = -errno;
1338         }
1339
1340         r = fchmod_and_chown(fd, TTY_MODE, 0, (gid_t) -1);
1341         if (r < 0) {
1342                 log_debug_errno(r, "Failed to chmod()/chown() VT, ignoring: %m");
1343                 if (q >= 0)
1344                         q = r;
1345         }
1346
1347         return q;
1348 }
1349
1350 int vt_release(int fd, bool restore) {
1351         assert(fd >= 0);
1352
1353         /* This function releases the VT by acknowledging the VT-switch signal
1354          * sent by the kernel and optionally reset the VT in text and auto
1355          * VT-switching modes. */
1356
1357         if (ioctl(fd, VT_RELDISP, 1) < 0)
1358                 return -errno;
1359
1360         if (restore)
1361                 return vt_restore(fd);
1362
1363         return 0;
1364 }
1365
1366 void get_log_colors(int priority, const char **on, const char **off, const char **highlight) {
1367         /* Note that this will initialize output variables only when there's something to output.
1368          * The caller must pre-initalize to "" or NULL as appropriate. */
1369
1370         if (priority <= LOG_ERR) {
1371                 if (on)
1372                         *on = ANSI_HIGHLIGHT_RED;
1373                 if (off)
1374                         *off = ANSI_NORMAL;
1375                 if (highlight)
1376                         *highlight = ANSI_HIGHLIGHT;
1377
1378         } else if (priority <= LOG_WARNING) {
1379                 if (on)
1380                         *on = ANSI_HIGHLIGHT_YELLOW;
1381                 if (off)
1382                         *off = ANSI_NORMAL;
1383                 if (highlight)
1384                         *highlight = ANSI_HIGHLIGHT;
1385
1386         } else if (priority <= LOG_NOTICE) {
1387                 if (on)
1388                         *on = ANSI_HIGHLIGHT;
1389                 if (off)
1390                         *off = ANSI_NORMAL;
1391                 if (highlight)
1392                         *highlight = ANSI_HIGHLIGHT_RED;
1393
1394         } else if (priority >= LOG_DEBUG) {
1395                 if (on)
1396                         *on = ANSI_GREY;
1397                 if (off)
1398                         *off = ANSI_NORMAL;
1399                 if (highlight)
1400                         *highlight = ANSI_HIGHLIGHT_RED;
1401         }
1402 }