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;
 724                 char *path;
 725
 726                 r = extract_first_word(&p, &tty, NULL, 0);
 727                 if (r < 0)
 728                         return r;
 729                 if (r == 0)
 730                         break;
 731
 732                 if (streq(tty, "tty0")) {
 733                         tty = mfree(tty);
 734                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 735                         if (r < 0)
 736                                 return r;
 737                 }
 738
 739                 path = strappend("/dev/", tty);
 740                 if (!path)
 741                         return -ENOMEM;
 742
 743                 if (access(path, F_OK) < 0) {
 744                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 745                         free(path);
 746                         continue;
 747                 }
 748
 749                 r = strv_consume(&l, path);
 750                 if (r < 0)
 751                         return r;
 752         }
 753
 754         if (strv_isempty(l)) {
 755                 log_debug("No devices found for system console");
 756                 goto fallback;
 757         }
 758
 759         *ret = TAKE_PTR(l);
 760
 761         return 0;
 762
 763 fallback:
 764         r = strv_extend(&l, "/dev/console");
 765         if (r < 0)
 766                 return r;
 767
 768         *ret = TAKE_PTR(l);
 769
 770         return 0;
 771 }
 772
 773 bool tty_is_vc_resolve(const char *tty) {
 774         _cleanup_free_ char *resolved = NULL;
 775
 776         assert(tty);
 777
 778         tty = skip_dev_prefix(tty);
 779
 780         if (streq(tty, "console")) {
 781                 if (resolve_dev_console(&resolved) < 0)
 782                         return false;
 783
 784                 tty = resolved;
 785         }
 786
 787         return tty_is_vc(tty);
 788 }
 789
 790 const char *default_term_for_tty(const char *tty) {
 791         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 792 }
 793
 794 int fd_columns(int fd) {
 795         struct winsize ws = {};
 796
 797         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 798                 return -errno;
 799
 800         if (ws.ws_col <= 0)
 801                 return -EIO;
 802
 803         return ws.ws_col;
 804 }
 805
 806 unsigned columns(void) {
 807         const char *e;
 808         int c;
 809
 810         if (cached_columns > 0)
 811                 return cached_columns;
 812
 813         c = 0;
 814         e = getenv("COLUMNS");
 815         if (e)
 816                 (void) safe_atoi(e, &c);
 817
 818         if (c <= 0 || c > USHRT_MAX) {
 819                 c = fd_columns(STDOUT_FILENO);
 820                 if (c <= 0)
 821                         c = 80;
 822         }
 823
 824         cached_columns = c;
 825         return cached_columns;
 826 }
 827
 828 int fd_lines(int fd) {
 829         struct winsize ws = {};
 830
 831         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 832                 return -errno;
 833
 834         if (ws.ws_row <= 0)
 835                 return -EIO;
 836
 837         return ws.ws_row;
 838 }
 839
 840 unsigned lines(void) {
 841         const char *e;
 842         int l;
 843
 844         if (cached_lines > 0)
 845                 return cached_lines;
 846
 847         l = 0;
 848         e = getenv("LINES");
 849         if (e)
 850                 (void) safe_atoi(e, &l);
 851
 852         if (l <= 0 || l > USHRT_MAX) {
 853                 l = fd_lines(STDOUT_FILENO);
 854                 if (l <= 0)
 855                         l = 24;
 856         }
 857
 858         cached_lines = l;
 859         return cached_lines;
 860 }
 861
 862 /* intended to be used as a SIGWINCH sighandler */
 863 void columns_lines_cache_reset(int signum) {
 864         cached_columns = 0;
 865         cached_lines = 0;
 866 }
 867
 868 void reset_terminal_feature_caches(void) {
 869         cached_columns = 0;
 870         cached_lines = 0;
 871
 872         cached_colors_enabled = -1;
 873         cached_underline_enabled = -1;
 874         cached_on_tty = -1;
 875 }
 876
 877 bool on_tty(void) {
 878
 879         /* We check both stdout and stderr, so that situations where pipes on the shell are used are reliably
 880          * recognized, regardless if only the output or the errors are piped to some place. Since on_tty() is generally
 881          * used to default to a safer, non-interactive, non-color mode of operation it's probably good to be defensive
 882          * here, and check for both. Note that we don't check for STDIN_FILENO, because it should fine to use fancy
 883          * terminal functionality when outputting stuff, even if the input is piped to us. */
 884
 885         if (cached_on_tty < 0)
 886                 cached_on_tty =
 887                         isatty(STDOUT_FILENO) > 0 &&
 888                         isatty(STDERR_FILENO) > 0;
 889
 890         return cached_on_tty;
 891 }
 892
 893 int getttyname_malloc(int fd, char **ret) {
 894         char path[PATH_MAX], *c; /* PATH_MAX is counted *with* the trailing NUL byte */
 895         int r;
 896
 897         assert(fd >= 0);
 898         assert(ret);
 899
 900         r = ttyname_r(fd, path, sizeof path); /* positive error */
 901         assert(r >= 0);
 902         if (r == ERANGE)
 903                 return -ENAMETOOLONG;
 904         if (r > 0)
 905                 return -r;
 906
 907         c = strdup(skip_dev_prefix(path));
 908         if (!c)
 909                 return -ENOMEM;
 910
 911         *ret = c;
 912         return 0;
 913 }
 914
 915 int getttyname_harder(int fd, char **ret) {
 916         _cleanup_free_ char *s = NULL;
 917         int r;
 918
 919         r = getttyname_malloc(fd, &s);
 920         if (r < 0)
 921                 return r;
 922
 923         if (streq(s, "tty"))
 924                 return get_ctty(0, NULL, ret);
 925
 926         *ret = TAKE_PTR(s);
 927         return 0;
 928 }
 929
 930 int get_ctty_devnr(pid_t pid, dev_t *d) {
 931         int r;
 932         _cleanup_free_ char *line = NULL;
 933         const char *p;
 934         unsigned long ttynr;
 935
 936         assert(pid >= 0);
 937
 938         p = procfs_file_alloca(pid, "stat");
 939         r = read_one_line_file(p, &line);
 940         if (r < 0)
 941                 return r;
 942
 943         p = strrchr(line, ')');
 944         if (!p)
 945                 return -EIO;
 946
 947         p++;
 948
 949         if (sscanf(p, " "
 950                    "%*c "  /* state */
 951                    "%*d "  /* ppid */
 952                    "%*d "  /* pgrp */
 953                    "%*d "  /* session */
 954                    "%lu ", /* ttynr */
 955                    &ttynr) != 1)
 956                 return -EIO;
 957
 958         if (major(ttynr) == 0 && minor(ttynr) == 0)
 959                 return -ENXIO;
 960
 961         if (d)
 962                 *d = (dev_t) ttynr;
 963
 964         return 0;
 965 }
 966
 967 int get_ctty(pid_t pid, dev_t *ret_devnr, char **ret) {
 968         _cleanup_free_ char *fn = NULL, *b = NULL;
 969         dev_t devnr;
 970         int r;
 971
 972         r = get_ctty_devnr(pid, &devnr);
 973         if (r < 0)
 974                 return r;
 975
 976         r = device_path_make_canonical(S_IFCHR, devnr, &fn);
 977         if (r < 0) {
 978                 if (r != -ENOENT) /* No symlink for this in /dev/char/? */
 979                         return r;
 980
 981                 if (major(devnr) == 136) {
 982                         /* This is an ugly hack: PTY devices are not listed in /dev/char/, as they don't follow the
 983                          * Linux device model. This means we have no nice way to match them up against their actual
 984                          * device node. Let's hence do the check by the fixed, assigned major number. Normally we try
 985                          * to avoid such fixed major/minor matches, but there appears to nother nice way to handle
 986                          * this. */
 987
 988                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
 989                                 return -ENOMEM;
 990                 } else {
 991                         /* Probably something similar to the ptys which have no symlink in /dev/char/. Let's return
 992                          * something vaguely useful. */
 993
 994                         r = device_path_make_major_minor(S_IFCHR, devnr, &fn);
 995                         if (r < 0)
 996                                 return r;
 997                 }
 998         }
 999
1000         if (!b) {
1001                 const char *w;
1002
1003                 w = path_startswith(fn, "/dev/");
1004                 if (w) {
1005                         b = strdup(w);
1006                         if (!b)
1007                                 return -ENOMEM;
1008                 } else
1009                         b = TAKE_PTR(fn);
1010         }
1011
1012         if (ret)
1013                 *ret = TAKE_PTR(b);
1014
1015         if (ret_devnr)
1016                 *ret_devnr = devnr;
1017
1018         return 0;
1019 }
1020
1021 int ptsname_malloc(int fd, char **ret) {
1022         size_t l = 100;
1023
1024         assert(fd >= 0);
1025         assert(ret);
1026
1027         for (;;) {
1028                 char *c;
1029
1030                 c = new(char, l);
1031                 if (!c)
1032                         return -ENOMEM;
1033
1034                 if (ptsname_r(fd, c, l) == 0) {
1035                         *ret = c;
1036                         return 0;
1037                 }
1038                 if (errno != ERANGE) {
1039                         free(c);
1040                         return -errno;
1041                 }
1042
1043                 free(c);
1044
1045                 if (l > SIZE_MAX / 2)
1046                         return -ENOMEM;
1047
1048                 l *= 2;
1049         }
1050 }
1051
1052 int ptsname_namespace(int pty, char **ret) {
1053         int no = -1, r;
1054
1055         /* Like ptsname(), but doesn't assume that the path is
1056          * accessible in the local namespace. */
1057
1058         r = ioctl(pty, TIOCGPTN, &no);
1059         if (r < 0)
1060                 return -errno;
1061
1062         if (no < 0)
1063                 return -EIO;
1064
1065         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1066                 return -ENOMEM;
1067
1068         return 0;
1069 }
1070
1071 int openpt_in_namespace(pid_t pid, int flags) {
1072         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1073         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1074         pid_t child;
1075         int r;
1076
1077         assert(pid > 0);
1078
1079         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1080         if (r < 0)
1081                 return r;
1082
1083         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1084                 return -errno;
1085
1086         r = namespace_fork("(sd-openptns)", "(sd-openpt)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
1087                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1088         if (r < 0)
1089                 return r;
1090         if (r == 0) {
1091                 int master;
1092
1093                 pair[0] = safe_close(pair[0]);
1094
1095                 master = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1096                 if (master < 0)
1097                         _exit(EXIT_FAILURE);
1098
1099                 if (unlockpt(master) < 0)
1100                         _exit(EXIT_FAILURE);
1101
1102                 if (send_one_fd(pair[1], master, 0) < 0)
1103                         _exit(EXIT_FAILURE);
1104
1105                 _exit(EXIT_SUCCESS);
1106         }
1107
1108         pair[1] = safe_close(pair[1]);
1109
1110         r = wait_for_terminate_and_check("(sd-openptns)", child, 0);
1111         if (r < 0)
1112                 return r;
1113         if (r != EXIT_SUCCESS)
1114                 return -EIO;
1115
1116         return receive_one_fd(pair[0], 0);
1117 }
1118
1119 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1120         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1121         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1122         pid_t child;
1123         int r;
1124
1125         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1126         if (r < 0)
1127                 return r;
1128
1129         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1130                 return -errno;
1131
1132         r = namespace_fork("(sd-terminalns)", "(sd-terminal)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
1133                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1134         if (r < 0)
1135                 return r;
1136         if (r == 0) {
1137                 int master;
1138
1139                 pair[0] = safe_close(pair[0]);
1140
1141                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1142                 if (master < 0)
1143                         _exit(EXIT_FAILURE);
1144
1145                 if (send_one_fd(pair[1], master, 0) < 0)
1146                         _exit(EXIT_FAILURE);
1147
1148                 _exit(EXIT_SUCCESS);
1149         }
1150
1151         pair[1] = safe_close(pair[1]);
1152
1153         r = wait_for_terminate_and_check("(sd-terminalns)", child, 0);
1154         if (r < 0)
1155                 return r;
1156         if (r != EXIT_SUCCESS)
1157                 return -EIO;
1158
1159         return receive_one_fd(pair[0], 0);
1160 }
1161
1162 static bool getenv_terminal_is_dumb(void) {
1163         const char *e;
1164
1165         e = getenv("TERM");
1166         if (!e)
1167                 return true;
1168
1169         return streq(e, "dumb");
1170 }
1171
1172 bool terminal_is_dumb(void) {
1173         if (!on_tty())
1174                 return true;
1175
1176         return getenv_terminal_is_dumb();
1177 }
1178
1179 bool colors_enabled(void) {
1180
1181         /* Returns true if colors are considered supported on our stdout. For that we check $SYSTEMD_COLORS first
1182          * (which is the explicit way to turn colors on/off). If that didn't work we turn colors off unless we are on a
1183          * 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
1184          * we are PID 1 then we do not check whether we are connected to a TTY, because we don't keep /dev/console open
1185          * continuously due to fear of SAK, and hence things are a bit weird. */
1186
1187         if (cached_colors_enabled < 0) {
1188                 int val;
1189
1190                 val = getenv_bool("SYSTEMD_COLORS");
1191                 if (val >= 0)
1192                         cached_colors_enabled = val;
1193                 else if (getpid_cached() == 1)
1194                         /* PID1 outputs to the console without holding it open all the time */
1195                         cached_colors_enabled = !getenv_terminal_is_dumb();
1196                 else
1197                         cached_colors_enabled = !terminal_is_dumb();
1198         }
1199
1200         return cached_colors_enabled;
1201 }
1202
1203 bool dev_console_colors_enabled(void) {
1204         _cleanup_free_ char *s = NULL;
1205         int b;
1206
1207         /* Returns true if we assume that color is supported on /dev/console.
1208          *
1209          * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
1210          * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
1211          * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
1212          * colors_enabled() operates. */
1213
1214         b = getenv_bool("SYSTEMD_COLORS");
1215         if (b >= 0)
1216                 return b;
1217
1218         if (getenv_for_pid(1, "TERM", &s) <= 0)
1219                 (void) proc_cmdline_get_key("TERM", 0, &s);
1220
1221         return !streq_ptr(s, "dumb");
1222 }
1223
1224 bool underline_enabled(void) {
1225
1226         if (cached_underline_enabled < 0) {
1227
1228                 /* The Linux console doesn't support underlining, turn it off, but only there. */
1229
1230                 if (colors_enabled())
1231                         cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
1232                 else
1233                         cached_underline_enabled = false;
1234         }
1235
1236         return cached_underline_enabled;
1237 }
1238
1239 int vt_default_utf8(void) {
1240         _cleanup_free_ char *b = NULL;
1241         int r;
1242
1243         /* Read the default VT UTF8 setting from the kernel */
1244
1245         r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
1246         if (r < 0)
1247                 return r;
1248
1249         return parse_boolean(b);
1250 }
1251
1252 int vt_verify_kbmode(int fd) {
1253         int curr_mode;
1254
1255         /*
1256          * Make sure we only adjust consoles in K_XLATE or K_UNICODE mode.
1257          * Otherwise we would (likely) interfere with X11's processing of the
1258          * key events.
1259          *
1260          * http://lists.freedesktop.org/archives/systemd-devel/2013-February/008573.html
1261          */
1262
1263         if (ioctl(fd, KDGKBMODE, &curr_mode) < 0)
1264                 return -errno;
1265
1266         return IN_SET(curr_mode, K_XLATE, K_UNICODE) ? 0 : -EBUSY;
1267 }
1268
1269 int vt_reset_keyboard(int fd) {
1270         int kb, r;
1271
1272         /* If we can't read the default, then default to unicode. It's 2017 after all. */
1273         kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
1274
1275         r = vt_verify_kbmode(fd);
1276         if (r == -EBUSY) {
1277                 log_debug_errno(r, "Keyboard is not in XLATE or UNICODE mode, not resetting: %m");
1278                 return 0;
1279         } else if (r < 0)
1280                 return r;
1281
1282         if (ioctl(fd, KDSKBMODE, kb) < 0)
1283                 return -errno;
1284
1285         return 0;
1286 }
1287
1288 int vt_restore(int fd) {
1289         static const struct vt_mode mode = {
1290                 .mode = VT_AUTO,
1291         };
1292         int r, q = 0;
1293
1294         r = ioctl(fd, KDSETMODE, KD_TEXT);
1295         if (r < 0)
1296                 q = log_debug_errno(errno, "Failed to set VT in text mode, ignoring: %m");
1297
1298         r = vt_reset_keyboard(fd);
1299         if (r < 0) {
1300                 log_debug_errno(r, "Failed to reset keyboard mode, ignoring: %m");
1301                 if (q >= 0)
1302                         q = r;
1303         }
1304
1305         r = ioctl(fd, VT_SETMODE, &mode);
1306         if (r < 0) {
1307                 log_debug_errno(errno, "Failed to set VT_AUTO mode, ignoring: %m");
1308                 if (q >= 0)
1309                         q = -errno;
1310         }
1311
1312         r = fchown(fd, 0, (gid_t) -1);
1313         if (r < 0) {
1314                 log_debug_errno(errno, "Failed to chown VT, ignoring: %m");
1315                 if (q >= 0)
1316                         q = -errno;
1317         }
1318
1319         return q;
1320 }
1321
1322 int vt_release(int fd, bool restore) {
1323         assert(fd >= 0);
1324
1325         /* This function releases the VT by acknowledging the VT-switch signal
1326          * sent by the kernel and optionally reset the VT in text and auto
1327          * VT-switching modes. */
1328
1329         if (ioctl(fd, VT_RELDISP, 1) < 0)
1330                 return -errno;
1331
1332         if (restore)
1333                 return vt_restore(fd);
1334
1335         return 0;
1336 }
1337
1338 void get_log_colors(int priority, const char **on, const char **off, const char **highlight) {
1339         /* Note that this will initialize output variables only when there's something to output.
1340          * The caller must pre-initalize to "" or NULL as appropriate. */
1341
1342         if (priority <= LOG_ERR) {
1343                 if (on)
1344                         *on = ANSI_HIGHLIGHT_RED;
1345                 if (off)
1346                         *off = ANSI_NORMAL;
1347                 if (highlight)
1348                         *highlight = ANSI_HIGHLIGHT;
1349
1350         } else if (priority <= LOG_WARNING) {
1351                 if (on)
1352                         *on = ANSI_HIGHLIGHT_YELLOW;
1353                 if (off)
1354                         *off = ANSI_NORMAL;
1355                 if (highlight)
1356                         *highlight = ANSI_HIGHLIGHT;
1357
1358         } else if (priority <= LOG_NOTICE) {
1359                 if (on)
1360                         *on = ANSI_HIGHLIGHT;
1361                 if (off)
1362                         *off = ANSI_NORMAL;
1363                 if (highlight)
1364                         *highlight = ANSI_HIGHLIGHT_RED;
1365
1366         } else if (priority >= LOG_DEBUG) {
1367                 if (on)
1368                         *on = ANSI_GREY;
1369                 if (off)
1370                         *off = ANSI_NORMAL;
1371                 if (highlight)
1372                         *highlight = ANSI_HIGHLIGHT_RED;
1373         }
1374 }