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 "def.h"
  25 #include "env-util.h"
  26 #include "fd-util.h"
  27 #include "fileio.h"
  28 #include "fs-util.h"
  29 #include "io-util.h"
  30 #include "log.h"
  31 #include "macro.h"
  32 #include "namespace-util.h"
  33 #include "parse-util.h"
  34 #include "path-util.h"
  35 #include "proc-cmdline.h"
  36 #include "process-util.h"
  37 #include "socket-util.h"
  38 #include "stat-util.h"
  39 #include "stdio-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         if (isatty(fd) < 1)
 244                 return log_debug_errno(errno, "Asked to reset a terminal that actually isn't a terminal: %m");
 245
 246         /* We leave locked terminal attributes untouched, so that Plymouth may set whatever it wants to set,
 247          * and we don't interfere with that. */
 248
 249         /* Disable exclusive mode, just in case */
 250         if (ioctl(fd, TIOCNXCL) < 0)
 251                 log_debug_errno(errno, "TIOCNXCL ioctl failed on TTY, ignoring: %m");
 252
 253         /* Switch to text mode */
 254         if (switch_to_text)
 255                 if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
 256                         log_debug_errno(errno, "KDSETMODE ioctl for switching to text mode failed on TTY, ignoring: %m");
 257
 258
 259         /* Set default keyboard mode */
 260         (void) vt_reset_keyboard(fd);
 261
 262         if (tcgetattr(fd, &termios) < 0) {
 263                 r = log_debug_errno(errno, "Failed to get terminal parameters: %m");
 264                 goto finish;
 265         }
 266
 267         /* We only reset the stuff that matters to the software. How
 268          * hardware is set up we don't touch assuming that somebody
 269          * else will do that for us */
 270
 271         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 272         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 273         termios.c_oflag |= ONLCR;
 274         termios.c_cflag |= CREAD;
 275         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 276
 277         termios.c_cc[VINTR]    =   03;  /* ^C */
 278         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 279         termios.c_cc[VERASE]   = 0177;
 280         termios.c_cc[VKILL]    =  025;  /* ^X */
 281         termios.c_cc[VEOF]     =   04;  /* ^D */
 282         termios.c_cc[VSTART]   =  021;  /* ^Q */
 283         termios.c_cc[VSTOP]    =  023;  /* ^S */
 284         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 285         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 286         termios.c_cc[VWERASE]  =  027;  /* ^W */
 287         termios.c_cc[VREPRINT] =  022;  /* ^R */
 288         termios.c_cc[VEOL]     =    0;
 289         termios.c_cc[VEOL2]    =    0;
 290
 291         termios.c_cc[VTIME]  = 0;
 292         termios.c_cc[VMIN]   = 1;
 293
 294         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 295                 r = -errno;
 296
 297 finish:
 298         /* Just in case, flush all crap out */
 299         (void) tcflush(fd, TCIOFLUSH);
 300
 301         return r;
 302 }
 303
 304 int reset_terminal(const char *name) {
 305         _cleanup_close_ int fd = -1;
 306
 307         /* We open the terminal with O_NONBLOCK here, to ensure we
 308          * don't block on carrier if this is a terminal with carrier
 309          * configured. */
 310
 311         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 312         if (fd < 0)
 313                 return fd;
 314
 315         return reset_terminal_fd(fd, true);
 316 }
 317
 318 int open_terminal(const char *name, int mode) {
 319         _cleanup_close_ int fd = -1;
 320         unsigned c = 0;
 321
 322         /*
 323          * If a TTY is in the process of being closed opening it might cause EIO. This is horribly awful, but
 324          * unlikely to be changed in the kernel. Hence we work around this problem by retrying a couple of
 325          * times.
 326          *
 327          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 328          */
 329
 330         if (mode & O_CREAT)
 331                 return -EINVAL;
 332
 333         for (;;) {
 334                 fd = open(name, mode, 0);
 335                 if (fd >= 0)
 336                         break;
 337
 338                 if (errno != EIO)
 339                         return -errno;
 340
 341                 /* Max 1s in total */
 342                 if (c >= 20)
 343                         return -errno;
 344
 345                 (void) usleep(50 * USEC_PER_MSEC);
 346                 c++;
 347         }
 348
 349         if (isatty(fd) < 1)
 350                 return negative_errno();
 351
 352         return TAKE_FD(fd);
 353 }
 354
 355 int acquire_terminal(
 356                 const char *name,
 357                 AcquireTerminalFlags flags,
 358                 usec_t timeout) {
 359
 360         _cleanup_close_ int notify = -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 = usec_sub_unsigned(now(CLOCK_MONOTONIC), ts);
 447                                 if (n >= timeout)
 448                                         return -ETIMEDOUT;
 449
 450                                 r = fd_wait_for_event(notify, POLLIN, usec_sub_unsigned(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 = -1;
 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         const char *e;
 530         int r;
 531
 532         /* Deallocate the VT if possible. If not possible
 533          * (i.e. because it is the active one), at least clear it
 534          * entirely (including the scrollback buffer). */
 535
 536         e = path_startswith(name, "/dev/");
 537         if (!e)
 538                 return -EINVAL;
 539
 540         if (tty_is_vc(name)) {
 541                 _cleanup_close_ int fd = -1;
 542                 unsigned u;
 543                 const char *n;
 544
 545                 n = startswith(e, "tty");
 546                 if (!n)
 547                         return -EINVAL;
 548
 549                 r = safe_atou(n, &u);
 550                 if (r < 0)
 551                         return r;
 552
 553                 if (u <= 0)
 554                         return -EINVAL;
 555
 556                 /* Try to deallocate */
 557                 fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 558                 if (fd < 0)
 559                         return fd;
 560
 561                 r = ioctl(fd, VT_DISALLOCATE, u);
 562                 if (r >= 0)
 563                         return 0;
 564                 if (errno != EBUSY)
 565                         return -errno;
 566         }
 567
 568         /* So this is not a VT (in which case we cannot deallocate it),
 569          * or we failed to deallocate. Let's at least clear the screen. */
 570
 571         _cleanup_close_ int fd2 = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 572         if (fd2 < 0)
 573                 return fd2;
 574
 575         (void) loop_write(fd2,
 576                           "\033[r"   /* clear scrolling region */
 577                           "\033[H"   /* move home */
 578                           "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 579                           10, false);
 580         return 0;
 581 }
 582
 583 int make_console_stdio(void) {
 584         int fd, r;
 585
 586         /* Make /dev/console the controlling terminal and stdin/stdout/stderr, if we can. If we can't use
 587          * /dev/null instead. This is particularly useful if /dev/console is turned off, e.g. if console=null
 588          * is specified on the kernel command line. */
 589
 590         fd = acquire_terminal("/dev/console", ACQUIRE_TERMINAL_FORCE|ACQUIRE_TERMINAL_PERMISSIVE, USEC_INFINITY);
 591         if (fd < 0) {
 592                 log_warning_errno(fd, "Failed to acquire terminal, using /dev/null stdin/stdout/stderr instead: %m");
 593
 594                 r = make_null_stdio();
 595                 if (r < 0)
 596                         return log_error_errno(r, "Failed to make /dev/null stdin/stdout/stderr: %m");
 597
 598         } else {
 599                 r = reset_terminal_fd(fd, true);
 600                 if (r < 0)
 601                         log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 602
 603                 r = rearrange_stdio(fd, fd, fd); /* This invalidates 'fd' both on success and on failure. */
 604                 if (r < 0)
 605                         return log_error_errno(r, "Failed to make terminal stdin/stdout/stderr: %m");
 606         }
 607
 608         reset_terminal_feature_caches();
 609         return 0;
 610 }
 611
 612 bool tty_is_vc(const char *tty) {
 613         assert(tty);
 614
 615         return vtnr_from_tty(tty) >= 0;
 616 }
 617
 618 bool tty_is_console(const char *tty) {
 619         assert(tty);
 620
 621         return streq(skip_dev_prefix(tty), "console");
 622 }
 623
 624 int vtnr_from_tty(const char *tty) {
 625         int i, r;
 626
 627         assert(tty);
 628
 629         tty = skip_dev_prefix(tty);
 630
 631         if (!startswith(tty, "tty") )
 632                 return -EINVAL;
 633
 634         if (tty[3] < '0' || tty[3] > '9')
 635                 return -EINVAL;
 636
 637         r = safe_atoi(tty+3, &i);
 638         if (r < 0)
 639                 return r;
 640
 641         if (i < 0 || i > 63)
 642                 return -EINVAL;
 643
 644         return i;
 645 }
 646
 647  int resolve_dev_console(char **ret) {
 648         _cleanup_free_ char *active = NULL;
 649         char *tty;
 650         int r;
 651
 652         assert(ret);
 653
 654         /* Resolve where /dev/console is pointing to, if /sys is actually ours (i.e. not read-only-mounted which is a
 655          * sign for container setups) */
 656
 657         if (path_is_read_only_fs("/sys") > 0)
 658                 return -ENOMEDIUM;
 659
 660         r = read_one_line_file("/sys/class/tty/console/active", &active);
 661         if (r < 0)
 662                 return r;
 663
 664         /* If multiple log outputs are configured the last one is what /dev/console points to */
 665         tty = strrchr(active, ' ');
 666         if (tty)
 667                 tty++;
 668         else
 669                 tty = active;
 670
 671         if (streq(tty, "tty0")) {
 672                 active = mfree(active);
 673
 674                 /* Get the active VC (e.g. tty1) */
 675                 r = read_one_line_file("/sys/class/tty/tty0/active", &active);
 676                 if (r < 0)
 677                         return r;
 678
 679                 tty = active;
 680         }
 681
 682         if (tty == active)
 683                 *ret = TAKE_PTR(active);
 684         else {
 685                 char *tmp;
 686
 687                 tmp = strdup(tty);
 688                 if (!tmp)
 689                         return -ENOMEM;
 690
 691                 *ret = tmp;
 692         }
 693
 694         return 0;
 695 }
 696
 697 int get_kernel_consoles(char ***ret) {
 698         _cleanup_strv_free_ char **l = NULL;
 699         _cleanup_free_ char *line = NULL;
 700         const char *p;
 701         int r;
 702
 703         assert(ret);
 704
 705         /* If /sys is mounted read-only this means we are running in some kind of container environment. In that
 706          * case /sys would reflect the host system, not us, hence ignore the data we can read from it. */
 707         if (path_is_read_only_fs("/sys") > 0)
 708                 goto fallback;
 709
 710         r = read_one_line_file("/sys/class/tty/console/active", &line);
 711         if (r < 0)
 712                 return r;
 713
 714         p = line;
 715         for (;;) {
 716                 _cleanup_free_ char *tty = NULL, *path = NULL;
 717
 718                 r = extract_first_word(&p, &tty, NULL, 0);
 719                 if (r < 0)
 720                         return r;
 721                 if (r == 0)
 722                         break;
 723
 724                 if (streq(tty, "tty0")) {
 725                         tty = mfree(tty);
 726                         r = read_one_line_file("/sys/class/tty/tty0/active", &tty);
 727                         if (r < 0)
 728                                 return r;
 729                 }
 730
 731                 path = path_join("/dev", tty);
 732                 if (!path)
 733                         return -ENOMEM;
 734
 735                 if (access(path, F_OK) < 0) {
 736                         log_debug_errno(errno, "Console device %s is not accessible, skipping: %m", path);
 737                         continue;
 738                 }
 739
 740                 r = strv_consume(&l, TAKE_PTR(path));
 741                 if (r < 0)
 742                         return r;
 743         }
 744
 745         if (strv_isempty(l)) {
 746                 log_debug("No devices found for system console");
 747                 goto fallback;
 748         }
 749
 750         *ret = TAKE_PTR(l);
 751
 752         return 0;
 753
 754 fallback:
 755         r = strv_extend(&l, "/dev/console");
 756         if (r < 0)
 757                 return r;
 758
 759         *ret = TAKE_PTR(l);
 760
 761         return 0;
 762 }
 763
 764 bool tty_is_vc_resolve(const char *tty) {
 765         _cleanup_free_ char *resolved = NULL;
 766
 767         assert(tty);
 768
 769         tty = skip_dev_prefix(tty);
 770
 771         if (streq(tty, "console")) {
 772                 if (resolve_dev_console(&resolved) < 0)
 773                         return false;
 774
 775                 tty = resolved;
 776         }
 777
 778         return tty_is_vc(tty);
 779 }
 780
 781 const char *default_term_for_tty(const char *tty) {
 782         return tty && tty_is_vc_resolve(tty) ? "linux" : "vt220";
 783 }
 784
 785 int fd_columns(int fd) {
 786         struct winsize ws = {};
 787
 788         if (fd < 0)
 789                 return -EBADF;
 790
 791         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 792                 return -errno;
 793
 794         if (ws.ws_col <= 0)
 795                 return -EIO;
 796
 797         return ws.ws_col;
 798 }
 799
 800 unsigned columns(void) {
 801         const char *e;
 802         int c;
 803
 804         if (cached_columns > 0)
 805                 return cached_columns;
 806
 807         c = 0;
 808         e = getenv("COLUMNS");
 809         if (e)
 810                 (void) safe_atoi(e, &c);
 811
 812         if (c <= 0 || c > USHRT_MAX) {
 813                 c = fd_columns(STDOUT_FILENO);
 814                 if (c <= 0)
 815                         c = 80;
 816         }
 817
 818         cached_columns = c;
 819         return cached_columns;
 820 }
 821
 822 int fd_lines(int fd) {
 823         struct winsize ws = {};
 824
 825         if (fd < 0)
 826                 return -EBADF;
 827
 828         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 829                 return -errno;
 830
 831         if (ws.ws_row <= 0)
 832                 return -EIO;
 833
 834         return ws.ws_row;
 835 }
 836
 837 unsigned lines(void) {
 838         const char *e;
 839         int l;
 840
 841         if (cached_lines > 0)
 842                 return cached_lines;
 843
 844         l = 0;
 845         e = getenv("LINES");
 846         if (e)
 847                 (void) safe_atoi(e, &l);
 848
 849         if (l <= 0 || l > USHRT_MAX) {
 850                 l = fd_lines(STDOUT_FILENO);
 851                 if (l <= 0)
 852                         l = 24;
 853         }
 854
 855         cached_lines = l;
 856         return cached_lines;
 857 }
 858
 859 /* intended to be used as a SIGWINCH sighandler */
 860 void columns_lines_cache_reset(int signum) {
 861         cached_columns = 0;
 862         cached_lines = 0;
 863 }
 864
 865 void reset_terminal_feature_caches(void) {
 866         cached_columns = 0;
 867         cached_lines = 0;
 868
 869         cached_color_mode = _COLOR_INVALID;
 870         cached_underline_enabled = -1;
 871         cached_on_tty = -1;
 872 }
 873
 874 bool on_tty(void) {
 875
 876         /* We check both stdout and stderr, so that situations where pipes on the shell are used are reliably
 877          * recognized, regardless if only the output or the errors are piped to some place. Since on_tty() is generally
 878          * used to default to a safer, non-interactive, non-color mode of operation it's probably good to be defensive
 879          * here, and check for both. Note that we don't check for STDIN_FILENO, because it should fine to use fancy
 880          * terminal functionality when outputting stuff, even if the input is piped to us. */
 881
 882         if (cached_on_tty < 0)
 883                 cached_on_tty =
 884                         isatty(STDOUT_FILENO) > 0 &&
 885                         isatty(STDERR_FILENO) > 0;
 886
 887         return cached_on_tty;
 888 }
 889
 890 int getttyname_malloc(int fd, char **ret) {
 891         char path[PATH_MAX], *c; /* PATH_MAX is counted *with* the trailing NUL byte */
 892         int r;
 893
 894         assert(fd >= 0);
 895         assert(ret);
 896
 897         r = ttyname_r(fd, path, sizeof path); /* positive error */
 898         assert(r >= 0);
 899         if (r == ERANGE)
 900                 return -ENAMETOOLONG;
 901         if (r > 0)
 902                 return -r;
 903
 904         c = strdup(skip_dev_prefix(path));
 905         if (!c)
 906                 return -ENOMEM;
 907
 908         *ret = c;
 909         return 0;
 910 }
 911
 912 int getttyname_harder(int fd, char **ret) {
 913         _cleanup_free_ char *s = NULL;
 914         int r;
 915
 916         r = getttyname_malloc(fd, &s);
 917         if (r < 0)
 918                 return r;
 919
 920         if (streq(s, "tty"))
 921                 return get_ctty(0, NULL, ret);
 922
 923         *ret = TAKE_PTR(s);
 924         return 0;
 925 }
 926
 927 int get_ctty_devnr(pid_t pid, dev_t *d) {
 928         int r;
 929         _cleanup_free_ char *line = NULL;
 930         const char *p;
 931         unsigned long ttynr;
 932
 933         assert(pid >= 0);
 934
 935         p = procfs_file_alloca(pid, "stat");
 936         r = read_one_line_file(p, &line);
 937         if (r < 0)
 938                 return r;
 939
 940         p = strrchr(line, ')');
 941         if (!p)
 942                 return -EIO;
 943
 944         p++;
 945
 946         if (sscanf(p, " "
 947                    "%*c "  /* state */
 948                    "%*d "  /* ppid */
 949                    "%*d "  /* pgrp */
 950                    "%*d "  /* session */
 951                    "%lu ", /* ttynr */
 952                    &ttynr) != 1)
 953                 return -EIO;
 954
 955         if (major(ttynr) == 0 && minor(ttynr) == 0)
 956                 return -ENXIO;
 957
 958         if (d)
 959                 *d = (dev_t) ttynr;
 960
 961         return 0;
 962 }
 963
 964 int get_ctty(pid_t pid, dev_t *ret_devnr, char **ret) {
 965         char pty[STRLEN("/dev/pts/") + DECIMAL_STR_MAX(dev_t) + 1];
 966         _cleanup_free_ char *buf = NULL;
 967         const char *fn = NULL, *w;
 968         dev_t devnr;
 969         int r;
 970
 971         r = get_ctty_devnr(pid, &devnr);
 972         if (r < 0)
 973                 return r;
 974
 975         r = device_path_make_canonical(S_IFCHR, devnr, &buf);
 976         if (r < 0) {
 977                 struct stat st;
 978
 979                 if (r != -ENOENT) /* No symlink for this in /dev/char/? */
 980                         return r;
 981
 982                 /* Maybe this is PTY? PTY devices are not listed in /dev/char/, as they don't follow the
 983                  * Linux device model and hence device_path_make_canonical() doesn't work for them. Let's
 984                  * assume this is a PTY for a moment, and check if the device node this would then map to in
 985                  * /dev/pts/ matches the one we are looking for. This way we don't have to hardcode the major
 986                  * number (which is 136 btw), but we still rely on the fact that PTY numbers map directly to
 987                  * the minor number of the pty. */
 988                 xsprintf(pty, "/dev/pts/%u", minor(devnr));
 989
 990                 if (stat(pty, &st) < 0) {
 991                         if (errno != ENOENT)
 992                                 return -errno;
 993
 994                 } else if (S_ISCHR(st.st_mode) && devnr == st.st_rdev) /* Bingo! */
 995                         fn = pty;
 996
 997                 if (!fn) {
 998                         /* Doesn't exist, or not a PTY? Probably something similar to the PTYs which have no
 999                          * symlink in /dev/char/. Let's return something vaguely useful. */
1000                         r = device_path_make_major_minor(S_IFCHR, devnr, &buf);
1001                         if (r < 0)
1002                                 return r;
1003
1004                         fn = buf;
1005                 }
1006         } else
1007                 fn = buf;
1008
1009         w = path_startswith(fn, "/dev/");
1010         if (!w)
1011                 return -EINVAL;
1012
1013         if (ret) {
1014                 _cleanup_free_ char *b = NULL;
1015
1016                 b = strdup(w);
1017                 if (!b)
1018                         return -ENOMEM;
1019
1020                 *ret = TAKE_PTR(b);
1021         }
1022
1023         if (ret_devnr)
1024                 *ret_devnr = devnr;
1025
1026         return 0;
1027 }
1028
1029 int ptsname_malloc(int fd, char **ret) {
1030         size_t l = 100;
1031
1032         assert(fd >= 0);
1033         assert(ret);
1034
1035         for (;;) {
1036                 char *c;
1037
1038                 c = new(char, l);
1039                 if (!c)
1040                         return -ENOMEM;
1041
1042                 if (ptsname_r(fd, c, l) == 0) {
1043                         *ret = c;
1044                         return 0;
1045                 }
1046                 if (errno != ERANGE) {
1047                         free(c);
1048                         return -errno;
1049                 }
1050
1051                 free(c);
1052
1053                 if (l > SIZE_MAX / 2)
1054                         return -ENOMEM;
1055
1056                 l *= 2;
1057         }
1058 }
1059
1060 int openpt_allocate(int flags, char **ret_slave) {
1061         _cleanup_close_ int fd = -1;
1062         _cleanup_free_ char *p = NULL;
1063         int r;
1064
1065         fd = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1066         if (fd < 0)
1067                 return -errno;
1068
1069         if (ret_slave) {
1070                 r = ptsname_malloc(fd, &p);
1071                 if (r < 0)
1072                         return r;
1073
1074                 if (!path_startswith(p, "/dev/pts/"))
1075                         return -EINVAL;
1076         }
1077
1078         if (unlockpt(fd) < 0)
1079                 return -errno;
1080
1081         if (ret_slave)
1082                 *ret_slave = TAKE_PTR(p);
1083
1084         return TAKE_FD(fd);
1085 }
1086
1087 static int ptsname_namespace(int pty, char **ret) {
1088         int no = -1, r;
1089
1090         /* Like ptsname(), but doesn't assume that the path is
1091          * accessible in the local namespace. */
1092
1093         r = ioctl(pty, TIOCGPTN, &no);
1094         if (r < 0)
1095                 return -errno;
1096
1097         if (no < 0)
1098                 return -EIO;
1099
1100         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1101                 return -ENOMEM;
1102
1103         return 0;
1104 }
1105
1106 int openpt_allocate_in_namespace(pid_t pid, int flags, char **ret_slave) {
1107         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1, fd = -1;
1108         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1109         pid_t child;
1110         int r;
1111
1112         assert(pid > 0);
1113
1114         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1115         if (r < 0)
1116                 return r;
1117
1118         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1119                 return -errno;
1120
1121         r = namespace_fork("(sd-openptns)", "(sd-openpt)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
1122                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1123         if (r < 0)
1124                 return r;
1125         if (r == 0) {
1126                 pair[0] = safe_close(pair[0]);
1127
1128                 fd = openpt_allocate(flags, NULL);
1129                 if (fd < 0)
1130                         _exit(EXIT_FAILURE);
1131
1132                 if (send_one_fd(pair[1], fd, 0) < 0)
1133                         _exit(EXIT_FAILURE);
1134
1135                 _exit(EXIT_SUCCESS);
1136         }
1137
1138         pair[1] = safe_close(pair[1]);
1139
1140         r = wait_for_terminate_and_check("(sd-openptns)", child, 0);
1141         if (r < 0)
1142                 return r;
1143         if (r != EXIT_SUCCESS)
1144                 return -EIO;
1145
1146         fd = receive_one_fd(pair[0], 0);
1147         if (fd < 0)
1148                 return fd;
1149
1150         if (ret_slave) {
1151                 r = ptsname_namespace(fd, ret_slave);
1152                 if (r < 0)
1153                         return r;
1154         }
1155
1156         return TAKE_FD(fd);
1157 }
1158
1159 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1160         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1161         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1162         pid_t child;
1163         int r;
1164
1165         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1166         if (r < 0)
1167                 return r;
1168
1169         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1170                 return -errno;
1171
1172         r = namespace_fork("(sd-terminalns)", "(sd-terminal)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
1173                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
1174         if (r < 0)
1175                 return r;
1176         if (r == 0) {
1177                 int master;
1178
1179                 pair[0] = safe_close(pair[0]);
1180
1181                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1182                 if (master < 0)
1183                         _exit(EXIT_FAILURE);
1184
1185                 if (send_one_fd(pair[1], master, 0) < 0)
1186                         _exit(EXIT_FAILURE);
1187
1188                 _exit(EXIT_SUCCESS);
1189         }
1190
1191         pair[1] = safe_close(pair[1]);
1192
1193         r = wait_for_terminate_and_check("(sd-terminalns)", child, 0);
1194         if (r < 0)
1195                 return r;
1196         if (r != EXIT_SUCCESS)
1197                 return -EIO;
1198
1199         return receive_one_fd(pair[0], 0);
1200 }
1201
1202 static bool getenv_terminal_is_dumb(void) {
1203         const char *e;
1204
1205         e = getenv("TERM");
1206         if (!e)
1207                 return true;
1208
1209         return streq(e, "dumb");
1210 }
1211
1212 bool terminal_is_dumb(void) {
1213         if (!on_tty())
1214                 return true;
1215
1216         return getenv_terminal_is_dumb();
1217 }
1218
1219 static ColorMode parse_systemd_colors(void) {
1220         const char *e;
1221         int r;
1222
1223         e = getenv("SYSTEMD_COLORS");
1224         if (!e)
1225                 return _COLOR_INVALID;
1226         if (streq(e, "16"))
1227                 return COLOR_16;
1228         if (streq(e, "256"))
1229                 return COLOR_256;
1230         r = parse_boolean(e);
1231         if (r >= 0)
1232                 return r > 0 ? COLOR_ON : COLOR_OFF;
1233         return _COLOR_INVALID;
1234 }
1235
1236 ColorMode get_color_mode(void) {
1237
1238         /* Returns the mode used to choose output colors. The possible modes are COLOR_OFF for no colors,
1239          * COLOR_16 for only the base 16 ANSI colors, COLOR_256 for more colors and COLOR_ON for unrestricted
1240          * color output. For that we check $SYSTEMD_COLORS first (which is the explicit way to
1241          * 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
1242          * 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
1243          * check whether we are connected to a TTY, because we don't keep /dev/console open continuously due to fear
1244          * of SAK, and hence things are a bit weird. */
1245         ColorMode m;
1246
1247         if (cached_color_mode < 0) {
1248                 m = parse_systemd_colors();
1249                 if (m >= 0)
1250                         cached_color_mode = m;
1251                 else if (getenv("NO_COLOR"))
1252                         /* We only check for the presence of the variable; value is ignored. */
1253                         cached_color_mode = COLOR_OFF;
1254
1255                 else if (getpid_cached() == 1)
1256                         /* PID1 outputs to the console without holding it open all the time.
1257                          *
1258                          * Note that the Linux console can only display 16 colors. We still enable 256 color
1259                          * mode even for PID1 output though (which typically goes to the Linux console),
1260                          * since the Linux console is able to parse the 256 color sequences and automatically
1261                          * map them to the closest color in the 16 color palette (since kernel 3.16). Doing
1262                          * 256 colors is nice for people who invoke systemd in a container or via a serial
1263                          * link or such, and use a true 256 color terminal to do so. */
1264                         cached_color_mode = getenv_terminal_is_dumb() ? COLOR_OFF : COLOR_256;
1265                 else
1266                         cached_color_mode = terminal_is_dumb() ? COLOR_OFF : COLOR_256;
1267         }
1268
1269         return cached_color_mode;
1270 }
1271
1272 bool dev_console_colors_enabled(void) {
1273         _cleanup_free_ char *s = NULL;
1274         ColorMode m;
1275
1276         /* Returns true if we assume that color is supported on /dev/console.
1277          *
1278          * For that we first check if we explicitly got told to use colors or not, by checking $SYSTEMD_COLORS. If that
1279          * isn't set we check whether PID 1 has $TERM set, and if not, whether TERM is set on the kernel command
1280          * line. If we find $TERM set we assume color if it's not set to "dumb", similarly to how regular
1281          * colors_enabled() operates. */
1282
1283         m = parse_systemd_colors();
1284         if (m >= 0)
1285                 return m;
1286
1287         if (getenv("NO_COLOR"))
1288                 return false;
1289
1290         if (getenv_for_pid(1, "TERM", &s) <= 0)
1291                 (void) proc_cmdline_get_key("TERM", 0, &s);
1292
1293         return !streq_ptr(s, "dumb");
1294 }
1295
1296 bool underline_enabled(void) {
1297
1298         if (cached_underline_enabled < 0) {
1299
1300                 /* The Linux console doesn't support underlining, turn it off, but only there. */
1301
1302                 if (colors_enabled())
1303                         cached_underline_enabled = !streq_ptr(getenv("TERM"), "linux");
1304                 else
1305                         cached_underline_enabled = false;
1306         }
1307
1308         return cached_underline_enabled;
1309 }
1310
1311 int vt_default_utf8(void) {
1312         _cleanup_free_ char *b = NULL;
1313         int r;
1314
1315         /* Read the default VT UTF8 setting from the kernel */
1316
1317         r = read_one_line_file("/sys/module/vt/parameters/default_utf8", &b);
1318         if (r < 0)
1319                 return r;
1320
1321         return parse_boolean(b);
1322 }
1323
1324 int vt_reset_keyboard(int fd) {
1325         int kb;
1326
1327         /* If we can't read the default, then default to unicode. It's 2017 after all. */
1328         kb = vt_default_utf8() != 0 ? K_UNICODE : K_XLATE;
1329
1330         if (ioctl(fd, KDSKBMODE, kb) < 0)
1331                 return -errno;
1332
1333         return 0;
1334 }
1335
1336 int vt_restore(int fd) {
1337         static const struct vt_mode mode = {
1338                 .mode = VT_AUTO,
1339         };
1340         int r, q = 0;
1341
1342         if (isatty(fd) < 1)
1343                 return log_debug_errno(errno, "Asked to restore the VT for an fd that does not refer to a terminal: %m");
1344
1345         if (ioctl(fd, KDSETMODE, KD_TEXT) < 0)
1346                 q = log_debug_errno(errno, "Failed to set VT in text mode, ignoring: %m");
1347
1348         r = vt_reset_keyboard(fd);
1349         if (r < 0) {
1350                 log_debug_errno(r, "Failed to reset keyboard mode, ignoring: %m");
1351                 if (q >= 0)
1352                         q = r;
1353         }
1354
1355         if (ioctl(fd, VT_SETMODE, &mode) < 0) {
1356                 log_debug_errno(errno, "Failed to set VT_AUTO mode, ignoring: %m");
1357                 if (q >= 0)
1358                         q = -errno;
1359         }
1360
1361         r = fchmod_and_chown(fd, TTY_MODE, 0, GID_INVALID);
1362         if (r < 0) {
1363                 log_debug_errno(r, "Failed to chmod()/chown() VT, ignoring: %m");
1364                 if (q >= 0)
1365                         q = r;
1366         }
1367
1368         return q;
1369 }
1370
1371 int vt_release(int fd, bool restore) {
1372         assert(fd >= 0);
1373
1374         /* This function releases the VT by acknowledging the VT-switch signal
1375          * sent by the kernel and optionally reset the VT in text and auto
1376          * VT-switching modes. */
1377
1378         if (isatty(fd) < 1)
1379                 return log_debug_errno(errno, "Asked to release the VT for an fd that does not refer to a terminal: %m");
1380
1381         if (ioctl(fd, VT_RELDISP, 1) < 0)
1382                 return -errno;
1383
1384         if (restore)
1385                 return vt_restore(fd);
1386
1387         return 0;
1388 }
1389
1390 void get_log_colors(int priority, const char **on, const char **off, const char **highlight) {
1391         /* Note that this will initialize output variables only when there's something to output.
1392          * The caller must pre-initialize to "" or NULL as appropriate. */
1393
1394         if (priority <= LOG_ERR) {
1395                 if (on)
1396                         *on = ansi_highlight_red();
1397                 if (off)
1398                         *off = ansi_normal();
1399                 if (highlight)
1400                         *highlight = ansi_highlight();
1401
1402         } else if (priority <= LOG_WARNING) {
1403                 if (on)
1404                         *on = ansi_highlight_yellow();
1405                 if (off)
1406                         *off = ansi_normal();
1407                 if (highlight)
1408                         *highlight = ansi_highlight();
1409
1410         } else if (priority <= LOG_NOTICE) {
1411                 if (on)
1412                         *on = ansi_highlight();
1413                 if (off)
1414                         *off = ansi_normal();
1415                 if (highlight)
1416                         *highlight = ansi_highlight_red();
1417
1418         } else if (priority >= LOG_DEBUG) {
1419                 if (on)
1420                         *on = ansi_grey();
1421                 if (off)
1422                         *off = ansi_normal();
1423                 if (highlight)
1424                         *highlight = ansi_highlight_red();
1425         }
1426 }