src/basic/terminal-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <limits.h>
  23 #include <stdarg.h>
  24 #include <stddef.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/inotify.h>
  28 #include <sys/socket.h>
  29 #include <sys/sysmacros.h>
  30 #include <sys/time.h>
  31 #include <linux/kd.h>
  32 #include <linux/tiocl.h>
  33 #include <linux/vt.h>
  34 #include <poll.h>
  35 #include <signal.h>
  36 #include <sys/ioctl.h>
  37 #include <sys/types.h>
  38 #include <termios.h>
  39 #include <unistd.h>
  40
  41 #include "alloc-util.h"
  42 #include "fd-util.h"
  43 #include "fileio.h"
  44 #include "fs-util.h"
  45 #include "io-util.h"
  46 #include "log.h"
  47 #include "macro.h"
  48 #include "parse-util.h"
  49 #include "process-util.h"
  50 #include "socket-util.h"
  51 #include "stat-util.h"
  52 #include "string-util.h"
  53 #include "terminal-util.h"
  54 #include "time-util.h"
  55 #include "util.h"
  56
  57 static volatile unsigned cached_columns = 0;
  58 static volatile unsigned cached_lines = 0;
  59
  60 int chvt(int vt) {
  61         _cleanup_close_ int fd;
  62
  63         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
  64         if (fd < 0)
  65                 return -errno;
  66
  67         if (vt <= 0) {
  68                 int tiocl[2] = {
  69                         TIOCL_GETKMSGREDIRECT,
  70                         0
  71                 };
  72
  73                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  74                         return -errno;
  75
  76                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  77         }
  78
  79         if (ioctl(fd, VT_ACTIVATE, vt) < 0)
  80                 return -errno;
  81
  82         return 0;
  83 }
  84
  85 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  86         struct termios old_termios, new_termios;
  87         char c, line[LINE_MAX];
  88
  89         assert(f);
  90         assert(ret);
  91
  92         if (tcgetattr(fileno(f), &old_termios) >= 0) {
  93                 new_termios = old_termios;
  94
  95                 new_termios.c_lflag &= ~ICANON;
  96                 new_termios.c_cc[VMIN] = 1;
  97                 new_termios.c_cc[VTIME] = 0;
  98
  99                 if (tcsetattr(fileno(f), TCSADRAIN, &new_termios) >= 0) {
 100                         size_t k;
 101
 102                         if (t != USEC_INFINITY) {
 103                                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0) {
 104                                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 105                                         return -ETIMEDOUT;
 106                                 }
 107                         }
 108
 109                         k = fread(&c, 1, 1, f);
 110
 111                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
 112
 113                         if (k <= 0)
 114                                 return -EIO;
 115
 116                         if (need_nl)
 117                                 *need_nl = c != '\n';
 118
 119                         *ret = c;
 120                         return 0;
 121                 }
 122         }
 123
 124         if (t != USEC_INFINITY) {
 125                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
 126                         return -ETIMEDOUT;
 127         }
 128
 129         errno = 0;
 130         if (!fgets(line, sizeof(line), f))
 131                 return errno > 0 ? -errno : -EIO;
 132
 133         truncate_nl(line);
 134
 135         if (strlen(line) != 1)
 136                 return -EBADMSG;
 137
 138         if (need_nl)
 139                 *need_nl = false;
 140
 141         *ret = line[0];
 142         return 0;
 143 }
 144
 145 int ask_char(char *ret, const char *replies, const char *text, ...) {
 146         int r;
 147
 148         assert(ret);
 149         assert(replies);
 150         assert(text);
 151
 152         for (;;) {
 153                 va_list ap;
 154                 char c;
 155                 bool need_nl = true;
 156
 157                 if (on_tty())
 158                         fputs(ANSI_HIGHLIGHT, stdout);
 159
 160                 va_start(ap, text);
 161                 vprintf(text, ap);
 162                 va_end(ap);
 163
 164                 if (on_tty())
 165                         fputs(ANSI_NORMAL, stdout);
 166
 167                 fflush(stdout);
 168
 169                 r = read_one_char(stdin, &c, USEC_INFINITY, &need_nl);
 170                 if (r < 0) {
 171
 172                         if (r == -EBADMSG) {
 173                                 puts("Bad input, please try again.");
 174                                 continue;
 175                         }
 176
 177                         putchar('\n');
 178                         return r;
 179                 }
 180
 181                 if (need_nl)
 182                         putchar('\n');
 183
 184                 if (strchr(replies, c)) {
 185                         *ret = c;
 186                         return 0;
 187                 }
 188
 189                 puts("Read unexpected character, please try again.");
 190         }
 191 }
 192
 193 int ask_string(char **ret, const char *text, ...) {
 194         assert(ret);
 195         assert(text);
 196
 197         for (;;) {
 198                 char line[LINE_MAX];
 199                 va_list ap;
 200
 201                 if (on_tty())
 202                         fputs(ANSI_HIGHLIGHT, stdout);
 203
 204                 va_start(ap, text);
 205                 vprintf(text, ap);
 206                 va_end(ap);
 207
 208                 if (on_tty())
 209                         fputs(ANSI_NORMAL, stdout);
 210
 211                 fflush(stdout);
 212
 213                 errno = 0;
 214                 if (!fgets(line, sizeof(line), stdin))
 215                         return errno > 0 ? -errno : -EIO;
 216
 217                 if (!endswith(line, "\n"))
 218                         putchar('\n');
 219                 else {
 220                         char *s;
 221
 222                         if (isempty(line))
 223                                 continue;
 224
 225                         truncate_nl(line);
 226                         s = strdup(line);
 227                         if (!s)
 228                                 return -ENOMEM;
 229
 230                         *ret = s;
 231                         return 0;
 232                 }
 233         }
 234 }
 235
 236 int reset_terminal_fd(int fd, bool switch_to_text) {
 237         struct termios termios;
 238         int r = 0;
 239
 240         /* Set terminal to some sane defaults */
 241
 242         assert(fd >= 0);
 243
 244         /* We leave locked terminal attributes untouched, so that
 245          * Plymouth may set whatever it wants to set, and we don't
 246          * interfere with that. */
 247
 248         /* Disable exclusive mode, just in case */
 249         (void) ioctl(fd, TIOCNXCL);
 250
 251         /* Switch to text mode */
 252         if (switch_to_text)
 253                 (void) ioctl(fd, KDSETMODE, KD_TEXT);
 254
 255         /* Enable console unicode mode */
 256         (void) ioctl(fd, KDSKBMODE, K_UNICODE);
 257
 258         if (tcgetattr(fd, &termios) < 0) {
 259                 r = -errno;
 260                 goto finish;
 261         }
 262
 263         /* We only reset the stuff that matters to the software. How
 264          * hardware is set up we don't touch assuming that somebody
 265          * else will do that for us */
 266
 267         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 268         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 269         termios.c_oflag |= ONLCR;
 270         termios.c_cflag |= CREAD;
 271         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 272
 273         termios.c_cc[VINTR]    =   03;  /* ^C */
 274         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 275         termios.c_cc[VERASE]   = 0177;
 276         termios.c_cc[VKILL]    =  025;  /* ^X */
 277         termios.c_cc[VEOF]     =   04;  /* ^D */
 278         termios.c_cc[VSTART]   =  021;  /* ^Q */
 279         termios.c_cc[VSTOP]    =  023;  /* ^S */
 280         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 281         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 282         termios.c_cc[VWERASE]  =  027;  /* ^W */
 283         termios.c_cc[VREPRINT] =  022;  /* ^R */
 284         termios.c_cc[VEOL]     =    0;
 285         termios.c_cc[VEOL2]    =    0;
 286
 287         termios.c_cc[VTIME]  = 0;
 288         termios.c_cc[VMIN]   = 1;
 289
 290         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 291                 r = -errno;
 292
 293 finish:
 294         /* Just in case, flush all crap out */
 295         (void) tcflush(fd, TCIOFLUSH);
 296
 297         return r;
 298 }
 299
 300 int reset_terminal(const char *name) {
 301         _cleanup_close_ int fd = -1;
 302
 303         /* We open the terminal with O_NONBLOCK here, to ensure we
 304          * don't block on carrier if this is a terminal with carrier
 305          * configured. */
 306
 307         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 308         if (fd < 0)
 309                 return fd;
 310
 311         return reset_terminal_fd(fd, true);
 312 }
 313
 314 int open_terminal(const char *name, int mode) {
 315         int fd, r;
 316         unsigned c = 0;
 317
 318         /*
 319          * If a TTY is in the process of being closed opening it might
 320          * cause EIO. This is horribly awful, but unlikely to be
 321          * changed in the kernel. Hence we work around this problem by
 322          * retrying a couple of times.
 323          *
 324          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 325          */
 326
 327         if (mode & O_CREAT)
 328                 return -EINVAL;
 329
 330         for (;;) {
 331                 fd = open(name, mode, 0);
 332                 if (fd >= 0)
 333                         break;
 334
 335                 if (errno != EIO)
 336                         return -errno;
 337
 338                 /* Max 1s in total */
 339                 if (c >= 20)
 340                         return -errno;
 341
 342                 usleep(50 * USEC_PER_MSEC);
 343                 c++;
 344         }
 345
 346         r = isatty(fd);
 347         if (r < 0) {
 348                 safe_close(fd);
 349                 return -errno;
 350         }
 351
 352         if (!r) {
 353                 safe_close(fd);
 354                 return -ENOTTY;
 355         }
 356
 357         return fd;
 358 }
 359
 360 int acquire_terminal(
 361                 const char *name,
 362                 bool fail,
 363                 bool force,
 364                 bool ignore_tiocstty_eperm,
 365                 usec_t timeout) {
 366
 367         int fd = -1, notify = -1, r = 0, wd = -1;
 368         usec_t ts = 0;
 369
 370         assert(name);
 371
 372         /* We use inotify to be notified when the tty is closed. We
 373          * create the watch before checking if we can actually acquire
 374          * it, so that we don't lose any event.
 375          *
 376          * Note: strictly speaking this actually watches for the
 377          * device being closed, it does *not* really watch whether a
 378          * tty loses its controlling process. However, unless some
 379          * rogue process uses TIOCNOTTY on /dev/tty *after* closing
 380          * its tty otherwise this will not become a problem. As long
 381          * as the administrator makes sure not configure any service
 382          * on the same tty as an untrusted user this should not be a
 383          * problem. (Which he probably should not do anyway.) */
 384
 385         if (timeout != USEC_INFINITY)
 386                 ts = now(CLOCK_MONOTONIC);
 387
 388         if (!fail && !force) {
 389                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 390                 if (notify < 0) {
 391                         r = -errno;
 392                         goto fail;
 393                 }
 394
 395                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 396                 if (wd < 0) {
 397                         r = -errno;
 398                         goto fail;
 399                 }
 400         }
 401
 402         for (;;) {
 403                 struct sigaction sa_old, sa_new = {
 404                         .sa_handler = SIG_IGN,
 405                         .sa_flags = SA_RESTART,
 406                 };
 407
 408                 if (notify >= 0) {
 409                         r = flush_fd(notify);
 410                         if (r < 0)
 411                                 goto fail;
 412                 }
 413
 414                 /* We pass here O_NOCTTY only so that we can check the return
 415                  * value TIOCSCTTY and have a reliable way to figure out if we
 416                  * successfully became the controlling process of the tty */
 417                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 418                 if (fd < 0)
 419                         return fd;
 420
 421                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 422                  * if we already own the tty. */
 423                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 424
 425                 /* First, try to get the tty */
 426                 if (ioctl(fd, TIOCSCTTY, force) < 0)
 427                         r = -errno;
 428
 429                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 430
 431                 /* Sometimes, it makes sense to ignore TIOCSCTTY
 432                  * returning EPERM, i.e. when very likely we already
 433                  * are have this controlling terminal. */
 434                 if (r < 0 && r == -EPERM && ignore_tiocstty_eperm)
 435                         r = 0;
 436
 437                 if (r < 0 && (force || fail || r != -EPERM))
 438                         goto fail;
 439
 440                 if (r >= 0)
 441                         break;
 442
 443                 assert(!fail);
 444                 assert(!force);
 445                 assert(notify >= 0);
 446
 447                 for (;;) {
 448                         union inotify_event_buffer buffer;
 449                         struct inotify_event *e;
 450                         ssize_t l;
 451
 452                         if (timeout != USEC_INFINITY) {
 453                                 usec_t n;
 454
 455                                 n = now(CLOCK_MONOTONIC);
 456                                 if (ts + timeout < n) {
 457                                         r = -ETIMEDOUT;
 458                                         goto fail;
 459                                 }
 460
 461                                 r = fd_wait_for_event(fd, POLLIN, ts + timeout - n);
 462                                 if (r < 0)
 463                                         goto fail;
 464
 465                                 if (r == 0) {
 466                                         r = -ETIMEDOUT;
 467                                         goto fail;
 468                                 }
 469                         }
 470
 471                         l = read(notify, &buffer, sizeof(buffer));
 472                         if (l < 0) {
 473                                 if (errno == EINTR || errno == EAGAIN)
 474                                         continue;
 475
 476                                 r = -errno;
 477                                 goto fail;
 478                         }
 479
 480                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 481                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) {
 482                                         r = -EIO;
 483                                         goto fail;
 484                                 }
 485                         }
 486
 487                         break;
 488                 }
 489
 490                 /* We close the tty fd here since if the old session
 491                  * ended our handle will be dead. It's important that
 492                  * we do this after sleeping, so that we don't enter
 493                  * an endless loop. */
 494                 fd = safe_close(fd);
 495         }
 496
 497         safe_close(notify);
 498
 499         return fd;
 500
 501 fail:
 502         safe_close(fd);
 503         safe_close(notify);
 504
 505         return r;
 506 }
 507
 508 int release_terminal(void) {
 509         static const struct sigaction sa_new = {
 510                 .sa_handler = SIG_IGN,
 511                 .sa_flags = SA_RESTART,
 512         };
 513
 514         _cleanup_close_ int fd = -1;
 515         struct sigaction sa_old;
 516         int r = 0;
 517
 518         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 519         if (fd < 0)
 520                 return -errno;
 521
 522         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 523          * by our own TIOCNOTTY */
 524         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 525
 526         if (ioctl(fd, TIOCNOTTY) < 0)
 527                 r = -errno;
 528
 529         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 530
 531         return r;
 532 }
 533
 534 int terminal_vhangup_fd(int fd) {
 535         assert(fd >= 0);
 536
 537         if (ioctl(fd, TIOCVHANGUP) < 0)
 538                 return -errno;
 539
 540         return 0;
 541 }
 542
 543 int terminal_vhangup(const char *name) {
 544         _cleanup_close_ int fd;
 545
 546         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 547         if (fd < 0)
 548                 return fd;
 549
 550         return terminal_vhangup_fd(fd);
 551 }
 552
 553 int vt_disallocate(const char *name) {
 554         _cleanup_close_ int fd = -1;
 555         unsigned u;
 556         int r;
 557
 558         /* Deallocate the VT if possible. If not possible
 559          * (i.e. because it is the active one), at least clear it
 560          * entirely (including the scrollback buffer) */
 561
 562         if (!startswith(name, "/dev/"))
 563                 return -EINVAL;
 564
 565         if (!tty_is_vc(name)) {
 566                 /* So this is not a VT. I guess we cannot deallocate
 567                  * it then. But let's at least clear the screen */
 568
 569                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 570                 if (fd < 0)
 571                         return fd;
 572
 573                 loop_write(fd,
 574                            "\033[r"    /* clear scrolling region */
 575                            "\033[H"    /* move home */
 576                            "\033[2J",  /* clear screen */
 577                            10, false);
 578                 return 0;
 579         }
 580
 581         if (!startswith(name, "/dev/tty"))
 582                 return -EINVAL;
 583
 584         r = safe_atou(name+8, &u);
 585         if (r < 0)
 586                 return r;
 587
 588         if (u <= 0)
 589                 return -EINVAL;
 590
 591         /* Try to deallocate */
 592         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 593         if (fd < 0)
 594                 return fd;
 595
 596         r = ioctl(fd, VT_DISALLOCATE, u);
 597         fd = safe_close(fd);
 598
 599         if (r >= 0)
 600                 return 0;
 601
 602         if (errno != EBUSY)
 603                 return -errno;
 604
 605         /* Couldn't deallocate, so let's clear it fully with
 606          * scrollback */
 607         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 608         if (fd < 0)
 609                 return fd;
 610
 611         loop_write(fd,
 612                    "\033[r"   /* clear scrolling region */
 613                    "\033[H"   /* move home */
 614                    "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 615                    10, false);
 616         return 0;
 617 }
 618
 619 int make_console_stdio(void) {
 620         int fd, r;
 621
 622         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 623
 624         fd = acquire_terminal("/dev/console", false, true, true, USEC_INFINITY);
 625         if (fd < 0)
 626                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 627
 628         r = reset_terminal_fd(fd, true);
 629         if (r < 0)
 630                 log_warning_errno(r, "Failed to reset terminal, ignoring: %m");
 631
 632         r = make_stdio(fd);
 633         if (r < 0)
 634                 return log_error_errno(r, "Failed to duplicate terminal fd: %m");
 635
 636         return 0;
 637 }
 638
 639 bool tty_is_vc(const char *tty) {
 640         assert(tty);
 641
 642         return vtnr_from_tty(tty) >= 0;
 643 }
 644
 645 bool tty_is_console(const char *tty) {
 646         assert(tty);
 647
 648         if (startswith(tty, "/dev/"))
 649                 tty += 5;
 650
 651         return streq(tty, "console");
 652 }
 653
 654 int vtnr_from_tty(const char *tty) {
 655         int i, r;
 656
 657         assert(tty);
 658
 659         if (startswith(tty, "/dev/"))
 660                 tty += 5;
 661
 662         if (!startswith(tty, "tty") )
 663                 return -EINVAL;
 664
 665         if (tty[3] < '0' || tty[3] > '9')
 666                 return -EINVAL;
 667
 668         r = safe_atoi(tty+3, &i);
 669         if (r < 0)
 670                 return r;
 671
 672         if (i < 0 || i > 63)
 673                 return -EINVAL;
 674
 675         return i;
 676 }
 677
 678 char *resolve_dev_console(char **active) {
 679         char *tty;
 680
 681         /* Resolve where /dev/console is pointing to, if /sys is actually ours
 682          * (i.e. not read-only-mounted which is a sign for container setups) */
 683
 684         if (path_is_read_only_fs("/sys") > 0)
 685                 return NULL;
 686
 687         if (read_one_line_file("/sys/class/tty/console/active", active) < 0)
 688                 return NULL;
 689
 690         /* If multiple log outputs are configured the last one is what
 691          * /dev/console points to */
 692         tty = strrchr(*active, ' ');
 693         if (tty)
 694                 tty++;
 695         else
 696                 tty = *active;
 697
 698         if (streq(tty, "tty0")) {
 699                 char *tmp;
 700
 701                 /* Get the active VC (e.g. tty1) */
 702                 if (read_one_line_file("/sys/class/tty/tty0/active", &tmp) >= 0) {
 703                         free(*active);
 704                         tty = *active = tmp;
 705                 }
 706         }
 707
 708         return tty;
 709 }
 710
 711 bool tty_is_vc_resolve(const char *tty) {
 712         _cleanup_free_ char *active = NULL;
 713
 714         assert(tty);
 715
 716         if (startswith(tty, "/dev/"))
 717                 tty += 5;
 718
 719         if (streq(tty, "console")) {
 720                 tty = resolve_dev_console(&active);
 721                 if (!tty)
 722                         return false;
 723         }
 724
 725         return tty_is_vc(tty);
 726 }
 727
 728 const char *default_term_for_tty(const char *tty) {
 729         return tty && tty_is_vc_resolve(tty) ? "TERM=linux" : "TERM=vt220";
 730 }
 731
 732 int fd_columns(int fd) {
 733         struct winsize ws = {};
 734
 735         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 736                 return -errno;
 737
 738         if (ws.ws_col <= 0)
 739                 return -EIO;
 740
 741         return ws.ws_col;
 742 }
 743
 744 unsigned columns(void) {
 745         const char *e;
 746         int c;
 747
 748         if (_likely_(cached_columns > 0))
 749                 return cached_columns;
 750
 751         c = 0;
 752         e = getenv("COLUMNS");
 753         if (e)
 754                 (void) safe_atoi(e, &c);
 755
 756         if (c <= 0)
 757                 c = fd_columns(STDOUT_FILENO);
 758
 759         if (c <= 0)
 760                 c = 80;
 761
 762         cached_columns = c;
 763         return cached_columns;
 764 }
 765
 766 int fd_lines(int fd) {
 767         struct winsize ws = {};
 768
 769         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 770                 return -errno;
 771
 772         if (ws.ws_row <= 0)
 773                 return -EIO;
 774
 775         return ws.ws_row;
 776 }
 777
 778 unsigned lines(void) {
 779         const char *e;
 780         int l;
 781
 782         if (_likely_(cached_lines > 0))
 783                 return cached_lines;
 784
 785         l = 0;
 786         e = getenv("LINES");
 787         if (e)
 788                 (void) safe_atoi(e, &l);
 789
 790         if (l <= 0)
 791                 l = fd_lines(STDOUT_FILENO);
 792
 793         if (l <= 0)
 794                 l = 24;
 795
 796         cached_lines = l;
 797         return cached_lines;
 798 }
 799
 800 /* intended to be used as a SIGWINCH sighandler */
 801 void columns_lines_cache_reset(int signum) {
 802         cached_columns = 0;
 803         cached_lines = 0;
 804 }
 805
 806 bool on_tty(void) {
 807         static int cached_on_tty = -1;
 808
 809         if (_unlikely_(cached_on_tty < 0))
 810                 cached_on_tty = isatty(STDOUT_FILENO) > 0;
 811
 812         return cached_on_tty;
 813 }
 814
 815 int make_stdio(int fd) {
 816         int r, s, t;
 817
 818         assert(fd >= 0);
 819
 820         r = dup2(fd, STDIN_FILENO);
 821         s = dup2(fd, STDOUT_FILENO);
 822         t = dup2(fd, STDERR_FILENO);
 823
 824         if (fd >= 3)
 825                 safe_close(fd);
 826
 827         if (r < 0 || s < 0 || t < 0)
 828                 return -errno;
 829
 830         /* Explicitly unset O_CLOEXEC, since if fd was < 3, then
 831          * dup2() was a NOP and the bit hence possibly set. */
 832         fd_cloexec(STDIN_FILENO, false);
 833         fd_cloexec(STDOUT_FILENO, false);
 834         fd_cloexec(STDERR_FILENO, false);
 835
 836         return 0;
 837 }
 838
 839 int make_null_stdio(void) {
 840         int null_fd;
 841
 842         null_fd = open("/dev/null", O_RDWR|O_NOCTTY);
 843         if (null_fd < 0)
 844                 return -errno;
 845
 846         return make_stdio(null_fd);
 847 }
 848
 849 int getttyname_malloc(int fd, char **ret) {
 850         size_t l = 100;
 851         int r;
 852
 853         assert(fd >= 0);
 854         assert(ret);
 855
 856         for (;;) {
 857                 char path[l];
 858
 859                 r = ttyname_r(fd, path, sizeof(path));
 860                 if (r == 0) {
 861                         const char *p;
 862                         char *c;
 863
 864                         p = startswith(path, "/dev/");
 865                         c = strdup(p ?: path);
 866                         if (!c)
 867                                 return -ENOMEM;
 868
 869                         *ret = c;
 870                         return 0;
 871                 }
 872
 873                 if (r != ERANGE)
 874                         return -r;
 875
 876                 l *= 2;
 877         }
 878
 879         return 0;
 880 }
 881
 882 int getttyname_harder(int fd, char **r) {
 883         int k;
 884         char *s = NULL;
 885
 886         k = getttyname_malloc(fd, &s);
 887         if (k < 0)
 888                 return k;
 889
 890         if (streq(s, "tty")) {
 891                 free(s);
 892                 return get_ctty(0, NULL, r);
 893         }
 894
 895         *r = s;
 896         return 0;
 897 }
 898
 899 int get_ctty_devnr(pid_t pid, dev_t *d) {
 900         int r;
 901         _cleanup_free_ char *line = NULL;
 902         const char *p;
 903         unsigned long ttynr;
 904
 905         assert(pid >= 0);
 906
 907         p = procfs_file_alloca(pid, "stat");
 908         r = read_one_line_file(p, &line);
 909         if (r < 0)
 910                 return r;
 911
 912         p = strrchr(line, ')');
 913         if (!p)
 914                 return -EIO;
 915
 916         p++;
 917
 918         if (sscanf(p, " "
 919                    "%*c "  /* state */
 920                    "%*d "  /* ppid */
 921                    "%*d "  /* pgrp */
 922                    "%*d "  /* session */
 923                    "%lu ", /* ttynr */
 924                    &ttynr) != 1)
 925                 return -EIO;
 926
 927         if (major(ttynr) == 0 && minor(ttynr) == 0)
 928                 return -ENXIO;
 929
 930         if (d)
 931                 *d = (dev_t) ttynr;
 932
 933         return 0;
 934 }
 935
 936 int get_ctty(pid_t pid, dev_t *_devnr, char **r) {
 937         char fn[sizeof("/dev/char/")-1 + 2*DECIMAL_STR_MAX(unsigned) + 1 + 1], *b = NULL;
 938         _cleanup_free_ char *s = NULL;
 939         const char *p;
 940         dev_t devnr;
 941         int k;
 942
 943         assert(r);
 944
 945         k = get_ctty_devnr(pid, &devnr);
 946         if (k < 0)
 947                 return k;
 948
 949         sprintf(fn, "/dev/char/%u:%u", major(devnr), minor(devnr));
 950
 951         k = readlink_malloc(fn, &s);
 952         if (k < 0) {
 953
 954                 if (k != -ENOENT)
 955                         return k;
 956
 957                 /* This is an ugly hack */
 958                 if (major(devnr) == 136) {
 959                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
 960                                 return -ENOMEM;
 961                 } else {
 962                         /* Probably something like the ptys which have no
 963                          * symlink in /dev/char. Let's return something
 964                          * vaguely useful. */
 965
 966                         b = strdup(fn + 5);
 967                         if (!b)
 968                                 return -ENOMEM;
 969                 }
 970         } else {
 971                 if (startswith(s, "/dev/"))
 972                         p = s + 5;
 973                 else if (startswith(s, "../"))
 974                         p = s + 3;
 975                 else
 976                         p = s;
 977
 978                 b = strdup(p);
 979                 if (!b)
 980                         return -ENOMEM;
 981         }
 982
 983         *r = b;
 984         if (_devnr)
 985                 *_devnr = devnr;
 986
 987         return 0;
 988 }
 989
 990 int ptsname_malloc(int fd, char **ret) {
 991         size_t l = 100;
 992
 993         assert(fd >= 0);
 994         assert(ret);
 995
 996         for (;;) {
 997                 char *c;
 998
 999                 c = new(char, l);
1000                 if (!c)
1001                         return -ENOMEM;
1002
1003                 if (ptsname_r(fd, c, l) == 0) {
1004                         *ret = c;
1005                         return 0;
1006                 }
1007                 if (errno != ERANGE) {
1008                         free(c);
1009                         return -errno;
1010                 }
1011
1012                 free(c);
1013                 l *= 2;
1014         }
1015 }
1016
1017 int ptsname_namespace(int pty, char **ret) {
1018         int no = -1, r;
1019
1020         /* Like ptsname(), but doesn't assume that the path is
1021          * accessible in the local namespace. */
1022
1023         r = ioctl(pty, TIOCGPTN, &no);
1024         if (r < 0)
1025                 return -errno;
1026
1027         if (no < 0)
1028                 return -EIO;
1029
1030         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1031                 return -ENOMEM;
1032
1033         return 0;
1034 }
1035
1036 int openpt_in_namespace(pid_t pid, int flags) {
1037         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1038         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1039         siginfo_t si;
1040         pid_t child;
1041         int r;
1042
1043         assert(pid > 0);
1044
1045         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1046         if (r < 0)
1047                 return r;
1048
1049         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1050                 return -errno;
1051
1052         child = fork();
1053         if (child < 0)
1054                 return -errno;
1055
1056         if (child == 0) {
1057                 int master;
1058
1059                 pair[0] = safe_close(pair[0]);
1060
1061                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
1062                 if (r < 0)
1063                         _exit(EXIT_FAILURE);
1064
1065                 master = posix_openpt(flags|O_NOCTTY|O_CLOEXEC);
1066                 if (master < 0)
1067                         _exit(EXIT_FAILURE);
1068
1069                 if (unlockpt(master) < 0)
1070                         _exit(EXIT_FAILURE);
1071
1072                 if (send_one_fd(pair[1], master, 0) < 0)
1073                         _exit(EXIT_FAILURE);
1074
1075                 _exit(EXIT_SUCCESS);
1076         }
1077
1078         pair[1] = safe_close(pair[1]);
1079
1080         r = wait_for_terminate(child, &si);
1081         if (r < 0)
1082                 return r;
1083         if (si.si_code != CLD_EXITED || si.si_status != EXIT_SUCCESS)
1084                 return -EIO;
1085
1086         return receive_one_fd(pair[0], 0);
1087 }
1088
1089 int open_terminal_in_namespace(pid_t pid, const char *name, int mode) {
1090         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
1091         _cleanup_close_pair_ int pair[2] = { -1, -1 };
1092         siginfo_t si;
1093         pid_t child;
1094         int r;
1095
1096         r = namespace_open(pid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
1097         if (r < 0)
1098                 return r;
1099
1100         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, pair) < 0)
1101                 return -errno;
1102
1103         child = fork();
1104         if (child < 0)
1105                 return -errno;
1106
1107         if (child == 0) {
1108                 int master;
1109
1110                 pair[0] = safe_close(pair[0]);
1111
1112                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
1113                 if (r < 0)
1114                         _exit(EXIT_FAILURE);
1115
1116                 master = open_terminal(name, mode|O_NOCTTY|O_CLOEXEC);
1117                 if (master < 0)
1118                         _exit(EXIT_FAILURE);
1119
1120                 if (send_one_fd(pair[1], master, 0) < 0)
1121                         _exit(EXIT_FAILURE);
1122
1123                 _exit(EXIT_SUCCESS);
1124         }
1125
1126         pair[1] = safe_close(pair[1]);
1127
1128         r = wait_for_terminate(child, &si);
1129         if (r < 0)
1130                 return r;
1131         if (si.si_code != CLD_EXITED || si.si_status != EXIT_SUCCESS)
1132                 return -EIO;
1133
1134         return receive_one_fd(pair[0], 0);
1135 }
1136
1137 bool colors_enabled(void) {
1138         const char *colors;
1139
1140         colors = getenv("SYSTEMD_COLORS");
1141         if (!colors) {
1142                 if (streq_ptr(getenv("TERM"), "dumb"))
1143                         return false;
1144                 return on_tty();
1145         }
1146
1147         return parse_boolean(colors) != 0;
1148 }