src/basic/terminal-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 Lennart Poettering
   6 ***/
   7
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <limits.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/socket.h>
  17 #include <sys/sysmacros.h>
  18 #include <sys/time.h>
  19 #include <linux/kd.h>
  20 #include <linux/tiocl.h>
  21 #include <linux/vt.h>
  22 #include <poll.h>
  23 #include <signal.h>
  24 #include <sys/ioctl.h>
  25 #include <sys/types.h>
  26 #include <termios.h>
  27 #include <unistd.h>
  28
  29 #include "alloc-util.h"
  30 #include "env-util.h"
  31 #include "fd-util.h"
  32 #include "fileio.h"
  33 #include "fs-util.h"
  34 #include "io-util.h"
  35 #include "log.h"
  36 #include "macro.h"
  37 #include "parse-util.h"
  38 #include "path-util.h"
  39 #include "proc-cmdline.h"
  40 #include "process-util.h"
  41 #include "socket-util.h"
  42 #include "stat-util.h"
  43 #include "string-util.h"
  44 #include "strv.h"
  45 #include "terminal-util.h"
  46 #include "time-util.h"
  47 #include "util.h"
  48
  49 static volatile unsigned cached_columns = 0;
  50 static volatile unsigned cached_lines = 0;
  51
  52 static volatile int cached_on_tty = -1;
  53 static volatile int cached_colors_enabled = -1;
  54 static volatile int cached_underline_enabled = -1;
  55
  56 int chvt(int vt) {
  57         _cleanup_close_ int fd;
  58
  59         /* Switch to the specified vt number. If the VT is specified <= 0 switch to the VT the kernel log messages go,
  60          * if that's configured. */
  61
  62         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
  63         if (fd < 0)
  64                 return -errno;
  65
  66         if (vt <= 0) {
  67                 int tiocl[2] = {
  68                         TIOCL_GETKMSGREDIRECT,
  69                         0
  70                 };
  71
  72                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  73                         return -errno;
  74
  75                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  76         }
  77
  78         if (ioctl(fd, VT_ACTIVATE, vt) < 0)
  79                 return -errno;
  80
  81         return 0;
  82 }
  83
  84 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  85         struct termios old_termios, new_termios;
  86         char c, line[LINE_MAX];
  87
  88         assert(f);
  89         assert(ret);
  90
  91         if (tcgetattr(fileno(f), &old_termios) >= 0) {
  92                 new_termios = old_termios;
  93
  94                 new_termios.c_lflag &= ~ICANON;
  95                 new_termios.c_cc[VMIN] = 1;
  96                 new_termios.c_cc[VTIME] = 0;
  97
  98                 if (tcsetattr(fileno(f), TCSADRAIN, &new_termios) >= 0) {
  99                         size_t k;
 100
 101                         if (t != USEC_INFINITY) {
 102                                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0) {
 103                                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 104                                         return -ETIMEDOUT;
 105                                 }
 106                         }
 107
 108                         k = fread(&c, 1, 1, f);
 109
 110                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 111
 112                         if (k <= 0)
 113                                 return -EIO;
 114
 115                         if (need_nl)
 116                                 *need_nl = c != '\n';
 117
 118                         *ret = c;
 119                         return 0;
 120                 }
 121         }
 122
 123         if (t != USEC_INFINITY) {
 124                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
 125                         return -ETIMEDOUT;
 126         }
 127
 128         errno = 0;
 129         if (!fgets(line, sizeof(line), f))
 130                 return errno > 0 ? -errno : -EIO;
 131
 132         truncate_nl(line);
 133
 134         if (strlen(line) != 1)
 135                 return -EBADMSG;
 136
 137         if (need_nl)
 138                 *need_nl = false;
 139
 140         *ret = line[0];
 141         return 0;
 142 }
 143
 144 #define DEFAULT_ASK_REFRESH_USEC (2*USEC_PER_SEC)
 145
 146 int ask_char(char *ret, const char *replies, const char *fmt, ...) {
 147         int r;
 148
 149         assert(ret);
 150         assert(replies);
 151         assert(fmt);
 152
 153         for (;;) {
 154                 va_list ap;
 155                 char c;
 156                 bool need_nl = true;
 157
 158                 if (colors_enabled())
 159                         fputs(ANSI_HIGHLIGHT, stdout);
 160
 161                 putchar('\r');
 162
 163                 va_start(ap, fmt);
 164                 vprintf(fmt, ap);
 165                 va_end(ap);
 166
 167                 if (colors_enabled())
 168                         fputs(ANSI_NORMAL, stdout);
 169
 170                 fflush(stdout);
 171
 172                 r = read_one_char(stdin, &c, DEFAULT_ASK_REFRESH_USEC, &need_nl);
 173                 if (r < 0) {
 174
 175                         if (r == -ETIMEDOUT)
 176                                 continue;
 177
 178                         if (r == -EBADMSG) {
 179                                 puts("Bad input, please try again.");
 180                                 continue;
 181                         }
 182
 183                         putchar('\n');
 184                         return r;
 185                 }
 186
 187                 if (need_nl)
 188                         putchar('\n');
 189
 190                 if (strchr(replies, c)) {
 191                         *ret = c;
 192                         return 0;
 193                 }
 194
 195                 puts("Read unexpected character, please try again.");
 196         }
 197 }
 198
 199 int ask_string(char **ret, const char *text, ...) {
 200         assert(ret);
 201         assert(text);
 202
 203         for (;;) {
 204                 char line[LINE_MAX];
 205                 va_list ap;
 206
 207                 if (colors_enabled())
 208                         fputs(ANSI_HIGHLIGHT, stdout);
 209
 210                 va_start(ap, text);
 211                 vprintf(text, ap);
 212                 va_end(ap);
 213
 214                 if (colors_enabled())
 215                         fputs(ANSI_NORMAL, stdout);
 216
 217                 fflush(stdout);
 218
 219                 errno = 0;
 220                 if (!fgets(line, sizeof(line), stdin))
 221                         return errno > 0 ? -errno : -EIO;
 222
 223                 if (!endswith(line, "\n"))
 224                         putchar('\n');
 225                 else {
 226                         char *s;
 227
 228                         if (isempty(line))
 229                                 continue;
 230
 231                         truncate_nl(line);
 232                         s = strdup(line);
 233                         if (!s)
 234                                 return -ENOMEM;
 235
 236                         *ret = s;
 237                         return 0;
 238                 }
 239         }
 240 }
 241
 242 int reset_terminal_fd(int fd, bool switch_to_text) {
 243         struct termios termios;
 244         int r = 0;
 245
 246         /* Set terminal to some sane defaults */
 247
 248         assert(fd >= 0);
 249
 250         /* We leave locked terminal attributes untouched, so that
 251          * Plymouth may set whatever it wants to set, and we don't
 252          * interfere with that. */
 253
 254         /* Disable exclusive mode, just in case */
 255         (void) ioctl(fd, TIOCNXCL);
 256
 257         /* Switch to text mode */
 258         if (switch_to_text)
 259                 (void) ioctl(fd, KDSETMODE, KD_TEXT);
 260
 261         /* Set default keyboard mode */
 262         (void) vt_reset_keyboard(fd);
 263
 264         if (tcgetattr(fd, &termios) < 0) {
 265                 r = -errno;
 266                 goto finish;
 267         }
 268
 269         /* We only reset the stuff that matters to the software. How
 270          * hardware is set up we don't touch assuming that somebody
 271          * else will do that for us */
 272
 273         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 274         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 275         termios.c_oflag |= ONLCR;
 276         termios.c_cflag |= CREAD;
 277         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 278
 279         termios.c_cc[VINTR]    =   03;  /* ^C */
 280         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 281         termios.c_cc[VERASE]   = 0177;
 282         termios.c_cc[VKILL]    =  025;  /* ^X */
 283         termios.c_cc[VEOF]     =   04;  /* ^D */
 284         termios.c_cc[VSTART]   =  021;  /* ^Q */
 285         termios.c_cc[VSTOP]    =  023;  /* ^S */
 286         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 287         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 288         termios.c_cc[VWERASE]  =  027;  /* ^W */
 289         termios.c_cc[VREPRINT] =  022;  /* ^R */
 290         termios.c_cc[VEOL]     =    0;
 291         termios.c_cc[VEOL2]    =    0;
 292
 293         termios.c_cc[VTIME]  = 0;
 294         termios.c_cc[VMIN]   = 1;
 295
 296         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 297                 r = -errno;
 298
 299 finish:
 300         /* Just in case, flush all crap out */
 301         (void) tcflush(fd, TCIOFLUSH);
 302
 303         return r;
 304 }
 305
 306 int reset_terminal(const char *name) {
 307         _cleanup_close_ int fd = -1;
 308
 309         /* We open the terminal with O_NONBLOCK here, to ensure we
 310          * don't block on carrier if this is a terminal with carrier
 311          * configured. */
 312
 313         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 314         if (fd < 0)
 315                 return fd;
 316
 317         return reset_terminal_fd(fd, true);
 318 }
 319
 320 int open_terminal(const char *name, int mode) {
 321         unsigned c = 0;
 322         int fd;
 323
 324         /*
 325          * If a TTY is in the process of being closed opening it might
 326          * cause EIO. This is horribly awful, but unlikely to be
 327          * changed in the kernel. Hence we work around this problem by
 328          * retrying a couple of times.
 329          *
 330          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 331          */
 332
 333         if (mode & O_CREAT)
 334                 return -EINVAL;
 335
 336         for (;;) {
 337                 fd = open(name, mode, 0);
 338                 if (fd >= 0)
 339                         break;
 340
 341                 if (errno != EIO)
 342                         return -errno;
 343
 344                 /* Max 1s in total */
 345                 if (c >= 20)
 346                         return -errno;
 347
 348                 usleep(50 * USEC_PER_MSEC);
 349                 c++;
 350         }
 351
 352         if (isatty(fd) <= 0) {
 353                 safe_close(fd);
 354                 return -ENOTTY;
 355         }
 356
 357         return fd;
 358 }
 359
 360 int acquire_terminal(
 361                 const char *name,
 362                 AcquireTerminalFlags flags,
 363                 usec_t timeout) {
 364
 365         _cleanup_close_ int notify = -1, fd = -1;
 366         usec_t ts = USEC_INFINITY;
 367         int r, wd = -1;
 368
 369         assert(name);
 370         assert(IN_SET(flags & ~ACQUIRE_TERMINAL_PERMISSIVE, ACQUIRE_TERMINAL_TRY, ACQUIRE_TERMINAL_FORCE, ACQUIRE_TERMINAL_WAIT));
 371
 372         /* We use inotify to be notified when the tty is closed. We create the watch before checking if we can actually
 373          * acquire it, so that we don't lose any event.
 374          *
 375          * Note: strictly speaking this actually watches for the device being closed, it does *not* really watch
 376          * whether a tty loses its controlling process. However, unless some rogue process uses TIOCNOTTY on /dev/tty
 377          * *after* closing its tty otherwise this will not become a problem. As long as the administrator makes sure to
 378          * not configure any service on the same tty as an untrusted user this should not be a problem. (Which they
 379          * probably should not do anyway.) */
 380
 381         if ((flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_WAIT) {
 382                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 383                 if (notify < 0)
 384                         return -errno;
 385
 386                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 387                 if (wd < 0)
 388                         return -errno;
 389
 390                 if (timeout != USEC_INFINITY)
 391                         ts = now(CLOCK_MONOTONIC);
 392         }
 393
 394         for (;;) {
 395                 struct sigaction sa_old, sa_new = {
 396                         .sa_handler = SIG_IGN,
 397                         .sa_flags = SA_RESTART,
 398                 };
 399
 400                 if (notify >= 0) {
 401                         r = flush_fd(notify);
 402                         if (r < 0)
 403                                 return r;
 404                 }
 405
 406                 /* We pass here O_NOCTTY only so that we can check the return value TIOCSCTTY and have a reliable way
 407                  * to figure out if we successfully became the controlling process of the tty */
 408                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 409                 if (fd < 0)
 410                         return fd;
 411
 412                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed if we already own the tty. */
 413                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 414
 415                 /* First, try to get the tty */
 416                 r = ioctl(fd, TIOCSCTTY,
 417                           (flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_FORCE) < 0 ? -errno : 0;
 418
 419                 /* Reset signal handler to old value */
 420                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 421
 422                 /* Success? Exit the loop now! */
 423                 if (r >= 0)
 424                         break;
 425
 426                 /* Any failure besides -EPERM? Fail, regardless of the mode. */
 427                 if (r != -EPERM)
 428                         return r;
 429
 430                 if (flags & ACQUIRE_TERMINAL_PERMISSIVE) /* If we are in permissive mode, then EPERM is fine, turn this
 431                                                           * into a success. Note that EPERM is also returned if we
 432                                                           * already are the owner of the TTY. */
 433                         break;
 434
 435                 if (flags != ACQUIRE_TERMINAL_WAIT) /* If we are in TRY or FORCE mode, then propagate EPERM as EPERM */
 436                         return r;
 437
 438                 assert(notify >= 0);
 439                 assert(wd >= 0);
 440
 441                 for (;;) {
 442                         union inotify_event_buffer buffer;
 443                         struct inotify_event *e;
 444                         ssize_t l;
 445
 446                         if (timeout != USEC_INFINITY) {
 447                                 usec_t n;
 448
 449                                 assert(ts != USEC_INFINITY);
 450
 451                                 n = now(CLOCK_MONOTONIC);
 452                                 if (ts + timeout < n)
 453                                         return -ETIMEDOUT;
 454
 455                                 r = fd_wait_for_event(notify, POLLIN, ts + timeout - n);
 456                                 if (r < 0)
 457                                         return r;
 458                                 if (r == 0)
 459                                         return -ETIMEDOUT;
 460                         }
 461
 462                         l = read(notify, &buffer, sizeof(buffer));
 463                         if (l < 0) {
 464                                 if (IN_SET(errno, EINTR, EAGAIN))
 465                                         continue;
 466
 467                                 return -errno;
 468                         }
 469
 470                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 471                                 if (e->mask & IN_Q_OVERFLOW) /* If we hit an inotify queue overflow, simply check if the terminal is up for grabs now. */
 472                                         break;
 473
 474                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) /* Safety checks */
 475                                         return -EIO;
 476                         }
 477
 478                         break;
 479                 }
 480
 481                 /* We close the tty fd here since if the old session ended our handle will be dead. It's important that
 482                  * we do this after sleeping, so that we don't enter an endless loop. */
 483                 fd = safe_close(fd);
 484         }
 485
 486         return TAKE_FD(fd);
 487 }
 488
 489 int release_terminal(void) {
 490         static const struct sigaction sa_new = {
 491                 .sa_handler = SIG_IGN,
 492                 .sa_flags = SA_RESTART,
 493         };
 494
 495         _cleanup_close_ int fd = -1;
 496         struct sigaction sa_old;
 497         int r;
 498
 499         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 500         if (fd < 0)
 501                 return -errno;
 502
 503         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 504          * by our own TIOCNOTTY */
 505         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 506
 507         r = ioctl(fd, TIOCNOTTY) < 0 ? -errno : 0;
 508
 509         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 510
 511         return r;
 512 }
 513
 514 int terminal_vhangup_fd(int fd) {
 515         assert(fd >= 0);
 516
 517         if (ioctl(fd, TIOCVHANGUP) < 0)
 518                 return -errno;
 519
 520         return 0;
 521 }
 522
 523 int terminal_vhangup(const char *name) {
 524         _cleanup_close_ int fd;
 525
 526         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 527         if (fd < 0)
 528                 return fd;
 529
 530         return terminal_vhangup_fd(fd);
 531 }
 532
 533 int vt_disallocate(const char *name) {
 534         _cleanup_close_ int fd = -1;
 535         const char *e, *n;
 536         unsigned u;
 537         int r;
 538
 539         /* Deallocate the VT if possible. If not possible
 540          * (i.e. because it is the active one), at least clear it
 541          * entirely (including the scrollback buffer) */
 542
 543         e = path_startswith(name, "/dev/");
 544         if (!e)
 545                 return -EINVAL;
 546
 547         if (!tty_is_vc(name)) {
 548                 /* So this is not a VT. I guess we cannot deallocate
 549                  * it then. But let's at least clear the screen */
 550
 551                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 552                 if (fd < 0)
 553                         return fd;
 554
 555                 loop_write(fd,
 556                            "\033[r"    /* clear scrolling region */
 557                            "\033[H"    /* move home */
 558                            "\033[2J",  /* clear screen */
 559                            10, false);
 560                 return 0;
 561         }
 562
 563         n = startswith(e, "tty");
 564         if (!n)
 565                 return -EINVAL;
 566
 567         r = safe_atou(n, &u);
 568         if (r < 0)
 569                 return r;
 570
 571         if (u <= 0)
 572                 return -EINVAL;
 573
 574         /* Try to deallocate */
 575         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 576         if (fd < 0)
 577                 return fd;
 578
 579         r = ioctl(fd, VT_DISALLOCATE, u);
 580         fd = safe_close(fd);
 581
 582         if (r >= 0)
 583                 return 0;
 584
 585         if (errno != EBUSY)
 586                 return -errno;
 587
 588         /* Couldn't deallocate, so let's clear it fully with
 589          * scrollback */
 590         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 591         if (fd < 0)
 592                 return fd;
 593
 594         loop_write(fd,
 595                    "\033[r"   /* clear scrolling region */
 596                    "\033[H"   /* move home */
 597                    "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 598                    10, false);
 599         return 0;
 600 }
 601
 602 int make_console_stdio(void) {
 603         int fd, r;
 604
 605         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 606
 607         fd = acquire_terminal("/dev/console", ACQUIRE_TERMINAL_FORCE|ACQUIRE_TERMINAL_PERMISSIVE, USEC_INFINITY);
 608         if (fd < 0)
 609                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 610
 611         r = reset_terminal_fd(fd, true);
 612         if (r < 0)
 613                 log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 614
 615         r = rearrange_stdio(fd, fd, fd); /* This invalidates 'fd' both on success and on failure. */
 616         if (r < 0)
 617                 return log_error_errno(r, "Failed to make terminal stdin/stdout/stderr: %m");
 618
 619         reset_terminal_feature_caches();
 620
 621         return 0;
 622 }
 623
 624 bool tty_is_vc(const char *tty) {
 625         assert(tty);
 626
 627         return vtnr_from_tty(tty) >= 0;
 628 }
 629
 630 bool tty_is_console(const char *tty) {
 631         assert(tty);
 632
 633         return streq(skip_dev_prefix(tty), "console");
 634 }
 635
 636 int vtnr_from_tty(const char *tty) {
 637         int i, r;
 638
 639         assert(tty);
 640
 641         tty = skip_dev_prefix(tty);
 642
 643         if (!startswith(tty, "tty") )
 644                 return -EINVAL;
 645
 646         if (tty[3] < '0' || tty[3] > '9')
 647                 return -EINVAL;
 648
 649         r = safe_atoi(tty+3, &i);
 650         if (r < 0)
 651                 return r;
 652
 653         if (i < 0 || i > 63)
 654                 return -EINVAL;
 655
 656         return i;
 657 }
 658
 659  int resolve_dev_console(char **ret) {
 660         _cleanup_free_ char *active = NULL;
 661         char *tty;
 662         int r;
 663
 664         assert(ret);
 665
 666         /* Resolve where /dev/console is pointing to, if /sys is actually ours (i.e. not read-only-mounted which is a
 667          * sign for container setups) */
 668
 669         if (path_is_read_only_fs("/sys") > 0)
 670                 return -ENOMEDIUM;
 671
 672         r = read_one_line_file("/sys/class/tty/console/active", &active);
 673         if (r < 0)
 674                 return r;
 675
 676         /* If multiple log outputs are configured the last one is what /dev/console points to */
 677         tty = strrchr(active, ' ');
 678         if (tty)
 679                 tty++;
 680         else
 681                 tty = active;
 682
 683         if (streq(tty, "tty0")) {
 684                 active = mfree(active);
 685
 686                 /* Get the active VC (e.g. tty1) */
 687                 r = read_one_line_file("/sys/class/tty/tty0/active", &active);
 688                 if (r < 0)
 689                         return r;
 690
 691                 tty = active;
 692         }
 693
 694         if (tty == active)
 695                 *ret = TAKE_PTR(active);
 696         else {
 697                 char *tmp;
 698
 699                 tmp = strdup(tty);
 700                 if (!tmp)
 701                         return -ENOMEM;
 702
 703                 *ret = tmp;
 704         }
 705
 706         return 0;
 707 }
 708
 709 int get_kernel_consoles(char ***ret) {
 710         _cleanup_strv_free_ char **l = NULL;
 711         _cleanup_free_ char *line = NULL;
 712         const char *p;
 713         int r;
 714
 715         assert(ret);
 716
 717         /* If /sys is mounted read-only this means we are running in some kind of container environment. In that
 718          * case /sys would reflect the host system, not us, hence ignore the data we can read from it. */
 719         if (path_is_read_only_fs("/sys") > 0)
 720                 goto fallback;
 721
 722         r = read_one_line_file("/sys/class/tty/console/active", &line);
 723         if (r < 0)
 724                 return r;
 725
 726         p = line;
 727         for (;;) {
 728                 _cleanup_free_ char *tty = NULL;
 729                 char *path;
 730
 731                 r = extract_first_word(&p, &tty, NULL, 0);
 732                 if (r < 0)
 733                         return r;
 734                 if (r == 0)
 735                         break;
 736
 737                 if (streq(tty, "tty0")) {
 738                         tty = mfree(tty);
 739                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 740                         if (r < 0)
 741                                 return r;
 742                 }
 743
 744                 path = strappend("/dev/", tty);
 745                 if (!path)
 746                         return -ENOMEM;
 747
 748                 if (access(path, F_OK) < 0) {
 749                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 750                         free(path);
 751                         continue;
 752                 }
 753
 754                 r = strv_consume(&l, path);
 755                 if (r < 0)
 756                         return r;
 757         }
 758
 759         if (strv_isempty(l)) {
 760                 log_debug("No devices found for system console");
 761                 goto fallback;
 762         }
 763
 764         *ret = TAKE_PTR(l);
 765
 766         return 0;
 767
 768 fallback:
 769         r = strv_extend(&l, "/dev/console");
 770         if (r < 0)
 771                 return r;
 772
 773         *ret = TAKE_PTR(l);
 774
 775         return 0;
 776 }
 777
 778 bool tty_is_vc_resolve(const char *tty) {
 779         _cleanup_free_ char *resolved = NULL;
 780
 781         assert(tty);
 782
 783         tty = skip_dev_prefix(tty);
 784
 785         if (streq(tty, "console")) {
 786                 if (resolve_dev_console(&resolved) < 0)
 787                         return false;
 788
 789                 tty = resolved;
 790         }
 791
 792         return tty_is_vc(tty);
 793 }
 794
 795 const char *default_term_for_tty(const char *tty) {
 796         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 797 }
 798
 799 int fd_columns(int fd) {
 800         struct winsize ws = {};
 801
 802         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 803                 return -errno;
 804
 805         if (ws.ws_col <= 0)
 806                 return -EIO;
 807
 808         return ws.ws_col;
 809 }
 810
 811 unsigned columns(void) {
 812         const char *e;
 813         int c;
 814
 815         if (cached_columns > 0)
 816                 return cached_columns;
 817
 818         c = 0;
 819         e = getenv("COLUMNS");
 820         if (e)
 821                 (void) safe_atoi(e, &c);
 822
 823         if (c <= 0)
 824                 c = fd_columns(STDOUT_FILENO);
 825
 826         if (c <= 0)
 827                 c = 80;
 828
 829         cached_columns = c;
 830         return cached_columns;
 831 }
 832
 833 int fd_lines(int fd) {
 834         struct winsize ws = {};
 835
 836         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 837                 return -errno;
 838
 839         if (ws.ws_row <= 0)
 840                 return -EIO;
 841
 842         return ws.ws_row;
 843 }
 844
 845 unsigned lines(void) {
 846         const char *e;
 847         int l;
 848
 849         if (cached_lines > 0)
 850                 return cached_lines;
 851
 852         l = 0;
 853         e = getenv("LINES");
 854         if (e)
 855                 (void) safe_atoi(e, &l);
 856
 857         if (l <= 0)
 858                 l = fd_lines(STDOUT_FILENO);
 859
 860         if (l <= 0)
 861                 l = 24;
 862
 863         cached_lines = l;
 864         return cached_lines;
 865 }
 866
 867 /* intended to be used as a SIGWINCH sighandler */
 868 void columns_lines_cache_reset(int signum) {
 869         cached_columns = 0;
 870         cached_lines = 0;
 871 }
 872
 873 void reset_terminal_feature_caches(void) {
 874         cached_columns = 0;
 875         cached_lines = 0;
 876
 877         cached_colors_enabled = -1;
 878         cached_underline_enabled = -1;
 879         cached_on_tty = -1;
 880 }
 881
 882 bool on_tty(void) {
 883         if (cached_on_tty < 0)
 884                 cached_on_tty = isatty(STDOUT_FILENO) > 0;
 885
 886         return cached_on_tty;
 887 }
 888
 889 int getttyname_malloc(int fd, char **ret) {
 890         size_t l = 100;
 891         int r;
 892
 893         assert(fd >= 0);
 894         assert(ret);
 895
 896         for (;;) {
 897                 char path[l];
 898
 899                 r = ttyname_r(fd, path, sizeof(path));
 900                 if (r == 0) {
 901                         char *c;
 902
 903                         c = strdup(skip_dev_prefix(path));
 904                         if (!c)
 905                                 return -ENOMEM;
 906
 907                         *ret = c;
 908                         return 0;
 909                 }
 910
 911                 if (r != ERANGE)
 912                         return -r;
 913
 914                 l *= 2;
 915         }
 916
 917         return 0;
 918 }
 919
 920 int getttyname_harder(int fd, char **r) {
 921         int k;
 922         char *s = NULL;
 923
 924         k = getttyname_malloc(fd, &s);
 925         if (k < 0)
 926                 return k;
 927
 928         if (streq(s, "tty")) {
 929                 free(s);
 930                 return get_ctty(0, NULL, r);
 931         }
 932
 933         *r = s;
 934         return 0;
 935 }
 936
 937 int get_ctty_devnr(pid_t pid, dev_t *d) {
 938         int r;
 939         _cleanup_free_ char *line = NULL;
 940         const char *p;
 941         unsigned long ttynr;
 942
 943         assert(pid >= 0);
 944
 945         p = procfs_file_alloca(pid, "stat");
 946         r = read_one_line_file(p, &line);
 947         if (r < 0)
 948                 return r;
 949
 950         p = strrchr(line, ')');
 951         if (!p)
 952                 return -EIO;
 953
 954         p++;
 955
 956         if (sscanf(p, " "
 957                    "%*c "  /* state */
 958                    "%*d "  /* ppid */
 959                    "%*d "  /* pgrp */
 960                    "%*d "  /* session */
 961                    "%lu ", /* ttynr */
 962                    &ttynr) != 1)
 963                 return -EIO;
 964
 965         if (major(ttynr) == 0 && minor(ttynr) == 0)
 966                 return -ENXIO;
 967
 968         if (d)
 969                 *d = (dev_t) ttynr;
 970
 971         return 0;
 972 }
 973
 974 int get_ctty(pid_t pid, dev_t *_devnr, char **r) {
 975         char fn[STRLEN("/dev/char/") + 2*DECIMAL_STR_MAX(unsigned) + 1 + 1], *b = NULL;
 976         _cleanup_free_ char *s = NULL;
 977         const char *p;
 978         dev_t devnr;
 979         int k;
 980
 981         assert(r);
 982
 983         k = get_ctty_devnr(pid, &devnr);
 984         if (k < 0)
 985                 return k;
 986
 987         sprintf(fn, "/dev/char/%u:%u", major(devnr), minor(devnr));
 988
 989         k = readlink_malloc(fn, &s);
 990         if (k < 0) {
 991
 992                 if (k != -ENOENT)
 993                         return k;
 994
 995                 /* This is an ugly hack */
 996                 if (major(devnr) == 136) {
 997                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
 998                                 return -ENOMEM;
 999                 } else {
1000                         /* Probably something like the ptys which have no
1001                          * symlink in /dev/char. Let's return something
1002                          * vaguely useful. */
1003
1004                         b = strdup(fn + 5);
1005                         if (!b)
1006                                 return -ENOMEM;
1007                 }
1008         } else {
1009                 if (startswith(s, "/dev/"))
1010                         p = s + 5;
1011                 else if (startswith(s, "../"))
1012                         p = s + 3;
1013                 else
1014                         p = s;
1015
1016                 b = strdup(p);
1017                 if (!b)
1018                         return -ENOMEM;
1019         }
1020
1021         *r = b;
1022         if (_devnr)
1023                 *_devnr = devnr;
1024
1025         return 0;
1026 }
1027
1028 int ptsname_malloc(int fd, char **ret) {
1029         size_t l = 100;
1030
1031         assert(fd >= 0);
1032         assert(ret);
1033
1034         for (;;) {
1035                 char *c;
1036
1037                 c = new(char, l);
1038                 if (!c)
1039                         return -ENOMEM;
1040
1041                 if (ptsname_r(fd, c, l) == 0) {
1042                         *ret = c;
1043                         return 0;
1044                 }
1045                 if (errno != ERANGE) {
1046                         free(c);
1047                         return -errno;
1048                 }
1049
1050                 free(c);
1051                 l *= 2;
1052         }
1053 }
1054
1055 int ptsname_namespace(int pty, char **ret) {
1056         int no = -1, r;
1057
1058         /* Like ptsname(), but doesn't assume that the path is
1059          * accessible in the local namespace. */
1060
1061         r = ioctl(pty, TIOCGPTN, &no);
1062         if (r < 0)
1063                 return -errno;
1064
1065         if (no < 0)
1066                 return -EIO;
1067
1068         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1069                 return -ENOMEM;
1070
1071         return 0;
1072 }
1073
1074 int openpt_in_namespace(pid_t pid, int flags) {
1075         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1076         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1077         pid_t child;
1078         int r;
1079
1080         assert(pid > 0);
1081
1082         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1083         if (r < 0)
1084                 return r;
1085
1086         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1087                 return -errno;
1088
1089         r = safe_fork("(sd-openpt)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &child);
1090         if (r < 0)
1091                 return r;
1092         if (r == 0) {
1093                 int master;
1094
1095                 pair[0] = safe_close(pair[0]);
1096
1097                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
1098                 if (r < 0)
1099                         _exit(EXIT_FAILURE);
1100
1101                 master = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1102                 if (master < 0)
1103                         _exit(EXIT_FAILURE);
1104
1105                 if (unlockpt(master) < 0)
1106                         _exit(EXIT_FAILURE);
1107
1108                 if (send_one_fd(pair[1], master, 0) < 0)
1109                         _exit(EXIT_FAILURE);
1110
1111                 _exit(EXIT_SUCCESS);
1112         }
1113
1114         pair[1] = safe_close(pair[1]);
1115
1116         r = wait_for_terminate_and_check("(sd-openpt)", child, 0);
1117         if (r < 0)
1118                 return r;
1119         if (r != EXIT_SUCCESS)
1120                 return -EIO;
1121
1122         return receive_one_fd(pair[0], 0);
1123 }
1124
1125 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1126         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1127         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1128         pid_t child;
1129         int r;
1130
1131         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1132         if (r < 0)
1133                 return r;
1134
1135         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1136                 return -errno;
1137
1138         r = safe_fork("(sd-terminal)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &child);
1139         if (r < 0)
1140                 return r;
1141         if (r == 0) {
1142                 int master;
1143
1144                 pair[0] = safe_close(pair[0]);
1145
1146                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
1147                 if (r < 0)
1148                         _exit(EXIT_FAILURE);
1149
1150                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1151                 if (master < 0)
1152                         _exit(EXIT_FAILURE);
1153
1154                 if (send_one_fd(pair[1], master, 0) < 0)
1155                         _exit(EXIT_FAILURE);
1156
1157                 _exit(EXIT_SUCCESS);
1158         }
1159
1160         pair[1] = safe_close(pair[1]);
1161
1162         r = wait_for_terminate_and_check("(sd-terminal)", child, 0);
1163         if (r < 0)
1164                 return r;
1165         if (r != EXIT_SUCCESS)
1166                 return -EIO;
1167
1168         return receive_one_fd(pair[0], 0);
1169 }
1170
1171 static bool getenv_terminal_is_dumb(void) {
1172         const char *e;
1173
1174         e = getenv("TERM");
1175         if (!e)
1176                 return true;
1177
1178         return streq(e, "dumb");
1179 }
1180
1181 bool terminal_is_dumb(void) {
1182         if (!on_tty())
1183                 return true;
1184
1185         return getenv_terminal_is_dumb();
1186 }
1187
1188 bool colors_enabled(void) {
1189
1190         /* Returns true if colors are considered supported on our stdout. For that we check $SYSTEMD_COLORS first
1191          * (which is the explicit way to turn colors on/off). If that didn't work we turn colors off unless we are on a
1192          * 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
1193          * we are PID 1 then we do not check whether we are connected to a TTY, because we don't keep /dev/console open
1194          * continously due to fear of SAK, and hence things are a bit weird. */
1195
1196         if (cached_colors_enabled < 0) {
1197                 int val;
1198
1199                 val = getenv_bool("SYSTEMD_COLORS");
1200                 if (val >= 0)
1201                         cached_colors_enabled = val;
1202                 else if (getpid_cached() == 1)
1203                         /* PID1 outputs to the console without holding it open all the time */
1204                         cached_colors_enabled = !getenv_terminal_is_dumb();
1205                 else
1206                         cached_colors_enabled = !terminal_is_dumb();
1207         }
1208
1209         return cached_colors_enabled;
1210 }
1211
1212 bool dev_console_colors_enabled(void) {
1213         _cleanup_free_ char *s = NULL;
1214         int b;
1215
1216         /* Returns true if we assume that color is supported on /dev/console.
1217          *
1218          * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
1219          * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
1220          * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
1221          * colors_enabled() operates. */
1222
1223         b = getenv_bool("SYSTEMD_COLORS");
1224         if (b >= 0)
1225                 return b;
1226
1227         if (getenv_for_pid(1, "TERM", &s) <= 0)
1228                 (void) proc_cmdline_get_key("TERM", 0, &s);
1229
1230         return !streq_ptr(s, "dumb");
1231 }
1232
1233 bool underline_enabled(void) {
1234
1235         if (cached_underline_enabled < 0) {
1236
1237                 /* The Linux console doesn't support underlining, turn it off, but only there. */
1238
1239                 if (colors_enabled())
1240                         cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
1241                 else
1242                         cached_underline_enabled = false;
1243         }
1244
1245         return cached_underline_enabled;
1246 }
1247
1248 int vt_default_utf8(void) {
1249         _cleanup_free_ char *b = NULL;
1250         int r;
1251
1252         /* Read the default VT UTF8 setting from the kernel */
1253
1254         r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
1255         if (r < 0)
1256                 return r;
1257
1258         return parse_boolean(b);
1259 }
1260
1261 int vt_reset_keyboard(int fd) {
1262         int kb;
1263
1264         /* If we can't read the default, then default to unicode. It's 2017 after all. */
1265         kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
1266
1267         if (ioctl(fd, KDSKBMODE, kb) < 0)
1268                 return -errno;
1269
1270         return 0;
1271 }