src/basic/terminal-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <limits.h>
   6 #include <linux/kd.h>
   7 #include <linux/tiocl.h>
   8 #include <linux/vt.h>
   9 #include <poll.h>
  10 #include <signal.h>
  11 #include <stdarg.h>
  12 #include <stddef.h>
  13 #include <stdlib.h>
  14 #include <sys/inotify.h>
  15 #include <sys/ioctl.h>
  16 #include <sys/sysmacros.h>
  17 #include <sys/time.h>
  18 #include <sys/types.h>
  19 #include <sys/utsname.h>
  20 #include <termios.h>
  21 #include <unistd.h>
  22
  23 #include "alloc-util.h"
  24 #include "copy.h"
  25 #include "def.h"
  26 #include "env-util.h"
  27 #include "fd-util.h"
  28 #include "fileio.h"
  29 #include "fs-util.h"
  30 #include "io-util.h"
  31 #include "log.h"
  32 #include "macro.h"
  33 #include "namespace-util.h"
  34 #include "parse-util.h"
  35 #include "path-util.h"
  36 #include "proc-cmdline.h"
  37 #include "process-util.h"
  38 #include "socket-util.h"
  39 #include "stat-util.h"
  40 #include "string-util.h"
  41 #include "strv.h"
  42 #include "terminal-util.h"
  43 #include "time-util.h"
  44 #include "user-util.h"
  45 #include "util.h"
  46
  47 static volatile unsigned cached_columns = 0;
  48 static volatile unsigned cached_lines = 0;
  49
  50 static volatile int cached_on_tty = -1;
  51 static volatile int cached_color_mode = _COLOR_INVALID;
  52 static volatile int cached_underline_enabled = -1;
  53
  54 int chvt(int vt) {
  55         _cleanup_close_ int fd = -1;
  56
  57         /* Switch to the specified vt number. If the VT is specified <= 0 switch to the VT the kernel log messages go,
  58          * if that's configured. */
  59
  60         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
  61         if (fd < 0)
  62                 return -errno;
  63
  64         if (vt <= 0) {
  65                 int tiocl[2] = {
  66                         TIOCL_GETKMSGREDIRECT,
  67                         0
  68                 };
  69
  70                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  71                         return -errno;
  72
  73                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  74         }
  75
  76         if (ioctl(fd, VT_ACTIVATE, vt) < 0)
  77                 return -errno;
  78
  79         return 0;
  80 }
  81
  82 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  83         _cleanup_free_ char *line = NULL;
  84         struct termios old_termios;
  85         int r, fd;
  86
  87         assert(f);
  88         assert(ret);
  89
  90         /* If this is a terminal, then switch canonical mode off, so that we can read a single
  91          * character. (Note that fmemopen() streams do not have an fd associated with them, let's handle that
  92          * nicely.) */
  93         fd = fileno(f);
  94         if (fd >= 0 && tcgetattr(fd, &old_termios) >= 0) {
  95                 struct termios new_termios = old_termios;
  96
  97                 new_termios.c_lflag &= ~ICANON;
  98                 new_termios.c_cc[VMIN] = 1;
  99                 new_termios.c_cc[VTIME] = 0;
 100
 101                 if (tcsetattr(fd, TCSADRAIN, &new_termios) >= 0) {
 102                         char c;
 103
 104                         if (t != USEC_INFINITY) {
 105                                 if (fd_wait_for_event(fd, POLLIN, t) <= 0) {
 106                                         (void) tcsetattr(fd, TCSADRAIN, &old_termios);
 107                                         return -ETIMEDOUT;
 108                                 }
 109                         }
 110
 111                         r = safe_fgetc(f, &c);
 112                         (void) tcsetattr(fd, TCSADRAIN, &old_termios);
 113                         if (r < 0)
 114                                 return r;
 115                         if (r == 0)
 116                                 return -EIO;
 117
 118                         if (need_nl)
 119                                 *need_nl = c != '\n';
 120
 121                         *ret = c;
 122                         return 0;
 123                 }
 124         }
 125
 126         if (t != USEC_INFINITY && fd > 0) {
 127                 /* Let's wait the specified amount of time for input. When we have no fd we skip this, under
 128                  * the assumption that this is an fmemopen() stream or so where waiting doesn't make sense
 129                  * anyway, as the data is either already in the stream or cannot possible be placed there
 130                  * while we access the stream */
 131
 132                 if (fd_wait_for_event(fd, POLLIN, t) <= 0)
 133                         return -ETIMEDOUT;
 134         }
 135
 136         /* If this is not a terminal, then read a full line instead */
 137
 138         r = read_line(f, 16, &line); /* longer than necessary, to eat up UTF-8 chars/vt100 key sequences */
 139         if (r < 0)
 140                 return r;
 141         if (r == 0)
 142                 return -EIO;
 143
 144         if (strlen(line) != 1)
 145                 return -EBADMSG;
 146
 147         if (need_nl)
 148                 *need_nl = false;
 149
 150         *ret = line[0];
 151         return 0;
 152 }
 153
 154 #define DEFAULT_ASK_REFRESH_USEC (2*USEC_PER_SEC)
 155
 156 int ask_char(char *ret, const char *replies, const char *fmt, ...) {
 157         int r;
 158
 159         assert(ret);
 160         assert(replies);
 161         assert(fmt);
 162
 163         for (;;) {
 164                 va_list ap;
 165                 char c;
 166                 bool need_nl = true;
 167
 168                 fputs(ansi_highlight(), stdout);
 169
 170                 putchar('\r');
 171
 172                 va_start(ap, fmt);
 173                 vprintf(fmt, ap);
 174                 va_end(ap);
 175
 176                 fputs(ansi_normal(), stdout);
 177
 178                 fflush(stdout);
 179
 180                 r = read_one_char(stdin, &c, DEFAULT_ASK_REFRESH_USEC, &need_nl);
 181                 if (r < 0) {
 182
 183                         if (r == -ETIMEDOUT)
 184                                 continue;
 185
 186                         if (r == -EBADMSG) {
 187                                 puts("Bad input, please try again.");
 188                                 continue;
 189                         }
 190
 191                         putchar('\n');
 192                         return r;
 193                 }
 194
 195                 if (need_nl)
 196                         putchar('\n');
 197
 198                 if (strchr(replies, c)) {
 199                         *ret = c;
 200                         return 0;
 201                 }
 202
 203                 puts("Read unexpected character, please try again.");
 204         }
 205 }
 206
 207 int ask_string(char **ret, const char *text, ...) {
 208         _cleanup_free_ char *line = NULL;
 209         va_list ap;
 210         int r;
 211
 212         assert(ret);
 213         assert(text);
 214
 215         fputs(ansi_highlight(), stdout);
 216
 217         va_start(ap, text);
 218         vprintf(text, ap);
 219         va_end(ap);
 220
 221         fputs(ansi_normal(), stdout);
 222
 223         fflush(stdout);
 224
 225         r = read_line(stdin, LONG_LINE_MAX, &line);
 226         if (r < 0)
 227                 return r;
 228         if (r == 0)
 229                 return -EIO;
 230
 231         *ret = TAKE_PTR(line);
 232         return 0;
 233 }
 234
 235 int reset_terminal_fd(int fd, bool switch_to_text) {
 236         struct termios termios;
 237         int r = 0;
 238
 239         /* Set terminal to some sane defaults */
 240
 241         assert(fd >= 0);
 242
 243         /* We leave locked terminal attributes untouched, so that
 244          * Plymouth may set whatever it wants to set, and we don't
 245          * interfere with that. */
 246
 247         /* Disable exclusive mode, just in case */
 248         if (ioctl(fd, TIOCNXCL) < 0)
 249                 log_debug_errno(errno, "TIOCNXCL ioctl failed on TTY, ignoring: %m");
 250
 251         /* Switch to text mode */
 252         if (switch_to_text)
 253                 if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
 254                         log_debug_errno(errno, "KDSETMODE ioctl for switching to text mode failed on TTY, ignoring: %m");
 255
 256
 257         /* Set default keyboard mode */
 258         (void) vt_reset_keyboard(fd);
 259
 260         if (tcgetattr(fd, &termios) < 0) {
 261                 r = log_debug_errno(errno, "Failed to get terminal parameters: %m");
 262                 goto finish;
 263         }
 264
 265         /* We only reset the stuff that matters to the software. How
 266          * hardware is set up we don't touch assuming that somebody
 267          * else will do that for us */
 268
 269         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 270         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 271         termios.c_oflag |= ONLCR;
 272         termios.c_cflag |= CREAD;
 273         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 274
 275         termios.c_cc[VINTR]    =   03;  /* ^C */
 276         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 277         termios.c_cc[VERASE]   = 0177;
 278         termios.c_cc[VKILL]    =  025;  /* ^X */
 279         termios.c_cc[VEOF]     =   04;  /* ^D */
 280         termios.c_cc[VSTART]   =  021;  /* ^Q */
 281         termios.c_cc[VSTOP]    =  023;  /* ^S */
 282         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 283         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 284         termios.c_cc[VWERASE]  =  027;  /* ^W */
 285         termios.c_cc[VREPRINT] =  022;  /* ^R */
 286         termios.c_cc[VEOL]     =    0;
 287         termios.c_cc[VEOL2]    =    0;
 288
 289         termios.c_cc[VTIME]  = 0;
 290         termios.c_cc[VMIN]   = 1;
 291
 292         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 293                 r = -errno;
 294
 295 finish:
 296         /* Just in case, flush all crap out */
 297         (void) tcflush(fd, TCIOFLUSH);
 298
 299         return r;
 300 }
 301
 302 int reset_terminal(const char *name) {
 303         _cleanup_close_ int fd = -1;
 304
 305         /* We open the terminal with O_NONBLOCK here, to ensure we
 306          * don't block on carrier if this is a terminal with carrier
 307          * configured. */
 308
 309         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 310         if (fd < 0)
 311                 return fd;
 312
 313         return reset_terminal_fd(fd, true);
 314 }
 315
 316 int open_terminal(const char *name, int mode) {
 317         unsigned c = 0;
 318         int fd;
 319
 320         /*
 321          * If a TTY is in the process of being closed opening it might
 322          * cause EIO. This is horribly awful, but unlikely to be
 323          * changed in the kernel. Hence we work around this problem by
 324          * retrying a couple of times.
 325          *
 326          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 327          */
 328
 329         if (mode & O_CREAT)
 330                 return -EINVAL;
 331
 332         for (;;) {
 333                 fd = open(name, mode, 0);
 334                 if (fd >= 0)
 335                         break;
 336
 337                 if (errno != EIO)
 338                         return -errno;
 339
 340                 /* Max 1s in total */
 341                 if (c >= 20)
 342                         return -errno;
 343
 344                 usleep(50 * USEC_PER_MSEC);
 345                 c++;
 346         }
 347
 348         if (isatty(fd) <= 0) {
 349                 safe_close(fd);
 350                 return -ENOTTY;
 351         }
 352
 353         return fd;
 354 }
 355
 356 int acquire_terminal(
 357                 const char *name,
 358                 AcquireTerminalFlags flags,
 359                 usec_t timeout) {
 360
 361         _cleanup_close_ int notify = -1, fd = -1;
 362         usec_t ts = USEC_INFINITY;
 363         int r, wd = -1;
 364
 365         assert(name);
 366         assert(IN_SET(flags & ~ACQUIRE_TERMINAL_PERMISSIVE, ACQUIRE_TERMINAL_TRY, ACQUIRE_TERMINAL_FORCE, ACQUIRE_TERMINAL_WAIT));
 367
 368         /* We use inotify to be notified when the tty is closed. We create the watch before checking if we can actually
 369          * acquire it, so that we don't lose any event.
 370          *
 371          * Note: strictly speaking this actually watches for the device being closed, it does *not* really watch
 372          * whether a tty loses its controlling process. However, unless some rogue process uses TIOCNOTTY on /dev/tty
 373          * *after* closing its tty otherwise this will not become a problem. As long as the administrator makes sure to
 374          * not configure any service on the same tty as an untrusted user this should not be a problem. (Which they
 375          * probably should not do anyway.) */
 376
 377         if ((flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_WAIT) {
 378                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 379                 if (notify < 0)
 380                         return -errno;
 381
 382                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 383                 if (wd < 0)
 384                         return -errno;
 385
 386                 if (timeout != USEC_INFINITY)
 387                         ts = now(CLOCK_MONOTONIC);
 388         }
 389
 390         for (;;) {
 391                 struct sigaction sa_old, sa_new = {
 392                         .sa_handler = SIG_IGN,
 393                         .sa_flags = SA_RESTART,
 394                 };
 395
 396                 if (notify >= 0) {
 397                         r = flush_fd(notify);
 398                         if (r < 0)
 399                                 return r;
 400                 }
 401
 402                 /* We pass here O_NOCTTY only so that we can check the return value TIOCSCTTY and have a reliable way
 403                  * to figure out if we successfully became the controlling process of the tty */
 404                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 405                 if (fd < 0)
 406                         return fd;
 407
 408                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed if we already own the tty. */
 409                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 410
 411                 /* First, try to get the tty */
 412                 r = ioctl(fd, TIOCSCTTY,
 413                           (flags & ~ACQUIRE_TERMINAL_PERMISSIVE) == ACQUIRE_TERMINAL_FORCE) < 0 ? -errno : 0;
 414
 415                 /* Reset signal handler to old value */
 416                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 417
 418                 /* Success? Exit the loop now! */
 419                 if (r >= 0)
 420                         break;
 421
 422                 /* Any failure besides -EPERM? Fail, regardless of the mode. */
 423                 if (r != -EPERM)
 424                         return r;
 425
 426                 if (flags & ACQUIRE_TERMINAL_PERMISSIVE) /* If we are in permissive mode, then EPERM is fine, turn this
 427                                                           * into a success. Note that EPERM is also returned if we
 428                                                           * already are the owner of the TTY. */
 429                         break;
 430
 431                 if (flags != ACQUIRE_TERMINAL_WAIT) /* If we are in TRY or FORCE mode, then propagate EPERM as EPERM */
 432                         return r;
 433
 434                 assert(notify >= 0);
 435                 assert(wd >= 0);
 436
 437                 for (;;) {
 438                         union inotify_event_buffer buffer;
 439                         struct inotify_event *e;
 440                         ssize_t l;
 441
 442                         if (timeout != USEC_INFINITY) {
 443                                 usec_t n;
 444
 445                                 assert(ts != USEC_INFINITY);
 446
 447                                 n = usec_sub_unsigned(now(CLOCK_MONOTONIC), ts);
 448                                 if (n >= timeout)
 449                                         return -ETIMEDOUT;
 450
 451                                 r = fd_wait_for_event(notify, POLLIN, usec_sub_unsigned(timeout, n));
 452                                 if (r < 0)
 453                                         return r;
 454                                 if (r == 0)
 455                                         return -ETIMEDOUT;
 456                         }
 457
 458                         l = read(notify, &buffer, sizeof(buffer));
 459                         if (l < 0) {
 460                                 if (IN_SET(errno, EINTR, EAGAIN))
 461                                         continue;
 462
 463                                 return -errno;
 464                         }
 465
 466                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 467                                 if (e->mask & IN_Q_OVERFLOW) /* If we hit an inotify queue overflow, simply check if the terminal is up for grabs now. */
 468                                         break;
 469
 470                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) /* Safety checks */
 471                                         return -EIO;
 472                         }
 473
 474                         break;
 475                 }
 476
 477                 /* We close the tty fd here since if the old session ended our handle will be dead. It's important that
 478                  * we do this after sleeping, so that we don't enter an endless loop. */
 479                 fd = safe_close(fd);
 480         }
 481
 482         return TAKE_FD(fd);
 483 }
 484
 485 int release_terminal(void) {
 486         static const struct sigaction sa_new = {
 487                 .sa_handler = SIG_IGN,
 488                 .sa_flags = SA_RESTART,
 489         };
 490
 491         _cleanup_close_ int fd = -1;
 492         struct sigaction sa_old;
 493         int r;
 494
 495         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 496         if (fd < 0)
 497                 return -errno;
 498
 499         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 500          * by our own TIOCNOTTY */
 501         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 502
 503         r = ioctl(fd, TIOCNOTTY) < 0 ? -errno : 0;
 504
 505         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 506
 507         return r;
 508 }
 509
 510 int terminal_vhangup_fd(int fd) {
 511         assert(fd >= 0);
 512
 513         if (ioctl(fd, TIOCVHANGUP) < 0)
 514                 return -errno;
 515
 516         return 0;
 517 }
 518
 519 int terminal_vhangup(const char *name) {
 520         _cleanup_close_ int fd = -1;
 521
 522         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 523         if (fd < 0)
 524                 return fd;
 525
 526         return terminal_vhangup_fd(fd);
 527 }
 528
 529 int vt_disallocate(const char *name) {
 530         const char *e;
 531         int r;
 532
 533         /* Deallocate the VT if possible. If not possible
 534          * (i.e. because it is the active one), at least clear it
 535          * entirely (including the scrollback buffer). */
 536
 537         e = path_startswith(name, "/dev/");
 538         if (!e)
 539                 return -EINVAL;
 540
 541         if (tty_is_vc(name)) {
 542                 _cleanup_close_ int fd = -1;
 543                 unsigned u;
 544                 const char *n;
 545
 546                 n = startswith(e, "tty");
 547                 if (!n)
 548                         return -EINVAL;
 549
 550                 r = safe_atou(n, &u);
 551                 if (r < 0)
 552                         return r;
 553
 554                 if (u <= 0)
 555                         return -EINVAL;
 556
 557                 /* Try to deallocate */
 558                 fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 559                 if (fd < 0)
 560                         return fd;
 561
 562                 r = ioctl(fd, VT_DISALLOCATE, u);
 563                 if (r >= 0)
 564                         return 0;
 565                 if (errno != EBUSY)
 566                         return -errno;
 567         }
 568
 569         /* So this is not a VT (in which case we cannot deallocate it),
 570          * or we failed to deallocate. Let's at least clear the screen. */
 571
 572         _cleanup_close_ int fd2 = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 573         if (fd2 < 0)
 574                 return fd2;
 575
 576         (void) loop_write(fd2,
 577                           "\033[r"   /* clear scrolling region */
 578                           "\033[H"   /* move home */
 579                           "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 580                           10, false);
 581         return 0;
 582 }
 583
 584 int make_console_stdio(void) {
 585         int fd, r;
 586
 587         /* Make /dev/console the controlling terminal and stdin/stdout/stderr, if we can. If we can't use
 588          * /dev/null instead. This is particularly useful if /dev/console is turned off, e.g. if console=null
 589          * is specified on the kernel command line. */
 590
 591         fd = acquire_terminal("/dev/console", ACQUIRE_TERMINAL_FORCE|ACQUIRE_TERMINAL_PERMISSIVE, USEC_INFINITY);
 592         if (fd < 0) {
 593                 log_warning_errno(fd, "Failed to acquire terminal, using /dev/null stdin/stdout/stderr instead: %m");
 594
 595                 r = make_null_stdio();
 596                 if (r < 0)
 597                         return log_error_errno(r, "Failed to make /dev/null stdin/stdout/stderr: %m");
 598
 599         } else {
 600                 r = reset_terminal_fd(fd, true);
 601                 if (r < 0)
 602                         log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 603
 604                 r = rearrange_stdio(fd, fd, fd); /* This invalidates 'fd' both on success and on failure. */
 605                 if (r < 0)
 606                         return log_error_errno(r, "Failed to make terminal stdin/stdout/stderr: %m");
 607         }
 608
 609         reset_terminal_feature_caches();
 610         return 0;
 611 }
 612
 613 bool tty_is_vc(const char *tty) {
 614         assert(tty);
 615
 616         return vtnr_from_tty(tty) >= 0;
 617 }
 618
 619 bool tty_is_console(const char *tty) {
 620         assert(tty);
 621
 622         return streq(skip_dev_prefix(tty), "console");
 623 }
 624
 625 int vtnr_from_tty(const char *tty) {
 626         int i, r;
 627
 628         assert(tty);
 629
 630         tty = skip_dev_prefix(tty);
 631
 632         if (!startswith(tty, "tty") )
 633                 return -EINVAL;
 634
 635         if (tty[3] < '0' || tty[3] > '9')
 636                 return -EINVAL;
 637
 638         r = safe_atoi(tty+3, &i);
 639         if (r < 0)
 640                 return r;
 641
 642         if (i < 0 || i > 63)
 643                 return -EINVAL;
 644
 645         return i;
 646 }
 647
 648  int resolve_dev_console(char **ret) {
 649         _cleanup_free_ char *active = NULL;
 650         char *tty;
 651         int r;
 652
 653         assert(ret);
 654
 655         /* Resolve where /dev/console is pointing to, if /sys is actually ours (i.e. not read-only-mounted which is a
 656          * sign for container setups) */
 657
 658         if (path_is_read_only_fs("/sys") > 0)
 659                 return -ENOMEDIUM;
 660
 661         r = read_one_line_file("/sys/class/tty/console/active", &active);
 662         if (r < 0)
 663                 return r;
 664
 665         /* If multiple log outputs are configured the last one is what /dev/console points to */
 666         tty = strrchr(active, ' ');
 667         if (tty)
 668                 tty++;
 669         else
 670                 tty = active;
 671
 672         if (streq(tty, "tty0")) {
 673                 active = mfree(active);
 674
 675                 /* Get the active VC (e.g. tty1) */
 676                 r = read_one_line_file("/sys/class/tty/tty0/active", &active);
 677                 if (r < 0)
 678                         return r;
 679
 680                 tty = active;
 681         }
 682
 683         if (tty == active)
 684                 *ret = TAKE_PTR(active);
 685         else {
 686                 char *tmp;
 687
 688                 tmp = strdup(tty);
 689                 if (!tmp)
 690                         return -ENOMEM;
 691
 692                 *ret = tmp;
 693         }
 694
 695         return 0;
 696 }
 697
 698 int get_kernel_consoles(char ***ret) {
 699         _cleanup_strv_free_ char **l = NULL;
 700         _cleanup_free_ char *line = NULL;
 701         const char *p;
 702         int r;
 703
 704         assert(ret);
 705
 706         /* If /sys is mounted read-only this means we are running in some kind of container environment. In that
 707          * case /sys would reflect the host system, not us, hence ignore the data we can read from it. */
 708         if (path_is_read_only_fs("/sys") > 0)
 709                 goto fallback;
 710
 711         r = read_one_line_file("/sys/class/tty/console/active", &line);
 712         if (r < 0)
 713                 return r;
 714
 715         p = line;
 716         for (;;) {
 717                 _cleanup_free_ char *tty = NULL, *path = NULL;
 718
 719                 r = extract_first_word(&p, &tty, NULL, 0);
 720                 if (r < 0)
 721                         return r;
 722                 if (r == 0)
 723                         break;
 724
 725                 if (streq(tty, "tty0")) {
 726                         tty = mfree(tty);
 727                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 728                         if (r < 0)
 729                                 return r;
 730                 }
 731
 732                 path = path_join("/dev", tty);
 733                 if (!path)
 734                         return -ENOMEM;
 735
 736                 if (access(path, F_OK) < 0) {
 737                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 738                         continue;
 739                 }
 740
 741                 r = strv_consume(&l, TAKE_PTR(path));
 742                 if (r < 0)
 743                         return r;
 744         }
 745
 746         if (strv_isempty(l)) {
 747                 log_debug("No devices found for system console");
 748                 goto fallback;
 749         }
 750
 751         *ret = TAKE_PTR(l);
 752
 753         return 0;
 754
 755 fallback:
 756         r = strv_extend(&l, "/dev/console");
 757         if (r < 0)
 758                 return r;
 759
 760         *ret = TAKE_PTR(l);
 761
 762         return 0;
 763 }
 764
 765 bool tty_is_vc_resolve(const char *tty) {
 766         _cleanup_free_ char *resolved = NULL;
 767
 768         assert(tty);
 769
 770         tty = skip_dev_prefix(tty);
 771
 772         if (streq(tty, "console")) {
 773                 if (resolve_dev_console(&resolved) < 0)
 774                         return false;
 775
 776                 tty = resolved;
 777         }
 778
 779         return tty_is_vc(tty);
 780 }
 781
 782 const char *default_term_for_tty(const char *tty) {
 783         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 784 }
 785
 786 int fd_columns(int fd) {
 787         struct winsize ws = {};
 788
 789         if (fd < 0)
 790                 return -EBADF;
 791
 792         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 793                 return -errno;
 794
 795         if (ws.ws_col <= 0)
 796                 return -EIO;
 797
 798         return ws.ws_col;
 799 }
 800
 801 unsigned columns(void) {
 802         const char *e;
 803         int c;
 804
 805         if (cached_columns > 0)
 806                 return cached_columns;
 807
 808         c = 0;
 809         e = getenv("COLUMNS");
 810         if (e)
 811                 (void) safe_atoi(e, &c);
 812
 813         if (c <= 0 || c > USHRT_MAX) {
 814                 c = fd_columns(STDOUT_FILENO);
 815                 if (c <= 0)
 816                         c = 80;
 817         }
 818
 819         cached_columns = c;
 820         return cached_columns;
 821 }
 822
 823 int fd_lines(int fd) {
 824         struct winsize ws = {};
 825
 826         if (fd < 0)
 827                 return -EBADF;
 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_color_mode = _COLOR_INVALID;
 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 static ColorMode parse_systemd_colors(void) {
1210         const char *e;
1211         int r;
1212
1213         e = getenv("SYSTEMD_COLORS");
1214         if (!e)
1215                 return _COLOR_INVALID;
1216         if (streq(e, "16"))
1217                 return COLOR_16;
1218         if (streq(e, "256"))
1219                 return COLOR_256;
1220         r = parse_boolean(e);
1221         if (r >= 0)
1222                 return r > 0 ? COLOR_ON : COLOR_OFF;
1223         return _COLOR_INVALID;
1224 }
1225
1226 ColorMode get_color_mode(void) {
1227
1228         /* Returns the mode used to choose output colors. The possible modes are COLOR_OFF for no colors,
1229          * COLOR_16 for only the base 16 ANSI colors, COLOR_256 for more colors and COLOR_ON for unrestricted
1230          * color output. For that we check $SYSTEMD_COLORS first (which is the explicit way to
1231          * change the mode). If that didn't work we turn colors off unless we are on a TTY. And if we are on a TTY
1232          * we turn it off if $TERM is set to "dumb". There's one special tweak though: if we are PID 1 then we do not
1233          * check whether we are connected to a TTY, because we don't keep /dev/console open continuously due to fear
1234          * of SAK, and hence things are a bit weird. */
1235         ColorMode m;
1236
1237         if (cached_color_mode < 0) {
1238                 m = parse_systemd_colors();
1239                 if (m >= 0)
1240                         cached_color_mode = m;
1241                 else if (getenv("NO_COLOR"))
1242                         /* We only check for the presence of the variable; value is ignored. */
1243                         cached_color_mode = COLOR_OFF;
1244
1245                 else if (getpid_cached() == 1)
1246                         /* PID1 outputs to the console without holding it open all the time.
1247                          *
1248                          * Note that the Linux console can only display 16 colors. We still enable 256 color
1249                          * mode even for PID1 output though (which typically goes to the Linux console),
1250                          * since the Linux console is able to parse the 256 color sequences and automatically
1251                          * map them to the closest color in the 16 color palette (since kernel 3.16). Doing
1252                          * 256 colors is nice for people who invoke systemd in a container or via a serial
1253                          * link or such, and use a true 256 color terminal to do so. */
1254                         cached_color_mode = getenv_terminal_is_dumb() ? COLOR_OFF : COLOR_256;
1255                 else
1256                         cached_color_mode = terminal_is_dumb() ? COLOR_OFF : COLOR_256;
1257         }
1258
1259         return cached_color_mode;
1260 }
1261
1262 bool dev_console_colors_enabled(void) {
1263         _cleanup_free_ char *s = NULL;
1264         ColorMode m;
1265
1266         /* Returns true if we assume that color is supported on /dev/console.
1267          *
1268          * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
1269          * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
1270          * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
1271          * colors_enabled() operates. */
1272
1273         m = parse_systemd_colors();
1274         if (m >= 0)
1275                 return m;
1276
1277         if (getenv("NO_COLOR"))
1278                 return false;
1279
1280         if (getenv_for_pid(1, "TERM", &s) <= 0)
1281                 (void) proc_cmdline_get_key("TERM", 0, &s);
1282
1283         return !streq_ptr(s, "dumb");
1284 }
1285
1286 bool underline_enabled(void) {
1287
1288         if (cached_underline_enabled < 0) {
1289
1290                 /* The Linux console doesn't support underlining, turn it off, but only there. */
1291
1292                 if (colors_enabled())
1293                         cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
1294                 else
1295                         cached_underline_enabled = false;
1296         }
1297
1298         return cached_underline_enabled;
1299 }
1300
1301 int vt_default_utf8(void) {
1302         _cleanup_free_ char *b = NULL;
1303         int r;
1304
1305         /* Read the default VT UTF8 setting from the kernel */
1306
1307         r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
1308         if (r < 0)
1309                 return r;
1310
1311         return parse_boolean(b);
1312 }
1313
1314 int vt_reset_keyboard(int fd) {
1315         int kb;
1316
1317         /* If we can't read the default, then default to unicode. It's 2017 after all. */
1318         kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
1319
1320         if (ioctl(fd, KDSKBMODE, kb) < 0)
1321                 return -errno;
1322
1323         return 0;
1324 }
1325
1326 int vt_restore(int fd) {
1327         static const struct vt_mode mode = {
1328                 .mode = VT_AUTO,
1329         };
1330         int r, q = 0;
1331
1332         if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
1333                 q = log_debug_errno(errno, "Failed to set VT in text mode, ignoring: %m");
1334
1335         r = vt_reset_keyboard(fd);
1336         if (r < 0) {
1337                 log_debug_errno(r, "Failed to reset keyboard mode, ignoring: %m");
1338                 if (q >= 0)
1339                         q = r;
1340         }
1341
1342         if (ioctl(fd, VT_SETMODE, &mode) < 0) {
1343                 log_debug_errno(errno, "Failed to set VT_AUTO mode, ignoring: %m");
1344                 if (q >= 0)
1345                         q = -errno;
1346         }
1347
1348         r = fchmod_and_chown(fd, TTY_MODE, 0, GID_INVALID);
1349         if (r < 0) {
1350                 log_debug_errno(r, "Failed to chmod()/chown() VT, ignoring: %m");
1351                 if (q >= 0)
1352                         q = r;
1353         }
1354
1355         return q;
1356 }
1357
1358 int vt_release(int fd, bool restore) {
1359         assert(fd >= 0);
1360
1361         /* This function releases the VT by acknowledging the VT-switch signal
1362          * sent by the kernel and optionally reset the VT in text and auto
1363          * VT-switching modes. */
1364
1365         if (ioctl(fd, VT_RELDISP, 1) < 0)
1366                 return -errno;
1367
1368         if (restore)
1369                 return vt_restore(fd);
1370
1371         return 0;
1372 }
1373
1374 void get_log_colors(int priority, const char **on, const char **off, const char **highlight) {
1375         /* Note that this will initialize output variables only when there's something to output.
1376          * The caller must pre-initialize to "" or NULL as appropriate. */
1377
1378         if (priority <= LOG_ERR) {
1379                 if (on)
1380                         *on = ansi_highlight_red();
1381                 if (off)
1382                         *off = ansi_normal();
1383                 if (highlight)
1384                         *highlight = ansi_highlight();
1385
1386         } else if (priority <= LOG_WARNING) {
1387                 if (on)
1388                         *on = ansi_highlight_yellow();
1389                 if (off)
1390                         *off = ansi_normal();
1391                 if (highlight)
1392                         *highlight = ansi_highlight();
1393
1394         } else if (priority <= LOG_NOTICE) {
1395                 if (on)
1396                         *on = ansi_highlight();
1397                 if (off)
1398                         *off = ansi_normal();
1399                 if (highlight)
1400                         *highlight = ansi_highlight_red();
1401
1402         } else if (priority >= LOG_DEBUG) {
1403                 if (on)
1404                         *on = ansi_grey();
1405                 if (off)
1406                         *off = ansi_normal();
1407                 if (highlight)
1408                         *highlight = ansi_highlight_red();
1409         }
1410 }