slattach.c

   1 /*
   2  * slattach     A program for handling dialup IP connecions.
   3  *              This program forces a TTY line to go into a special
   4  *              terminal line discipline, so that it can be used for
   5  *              network traffic instead of the regular terminal I/O.
   6  *
   7  * Usage:       slattach [-ehlmnqv] [ -k keepalive ] [ -o outfill ]
   8  *                      [-c cmd] [-s speed] [-p protocol] tty | -
   9  *
  10  * Version:     @(#)slattach.c  1.20  1999-05-29
  11  *
  12  * Author:      Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  13  *              Copyright 1988-1993 MicroWalt Corporation
  14  *
  15  * Modified:
  16  *              Alan Cox, <A.Cox@swansea.ac.uk> , July 16 1994
  17  *              Miquel van Smoorenburg, <miquels@drinkel.ow.org>, October 1994
  18  *              George Shearer, <gshearer@one.net>, January 3, 1995
  19  *              Yossi Gottlieb, <yogo@math.tau.ac.il>, February 11, 1995
  20  *              Peter Tobias, <tobias@et-inf.fho-emden.de>, July 30 1995
  21  *              Bernd Eckenfels <net-tools@lina.inka.de>, May 29, 1999
  22  *                      added some more printf's for debug and NOBLOCK to open
  23  *                      this should be enough to support 2.2 ttyS-style locks
  24  *
  25  *              This program is free software; you can redistribute it
  26  *              and/or  modify it under  the terms of  the GNU General
  27  *              Public  License as  published  by  the  Free  Software
  28  *              Foundation;  either  version 2 of the License, or  (at
  29  *              your option) any later version.
  30  */
  31 #include <sys/param.h>
  32 #include <sys/types.h>
  33 #include <sys/socket.h>
  34 #include <sys/ioctl.h>
  35 #include <sys/stat.h>
  36 #include <stdio.h>
  37 #include <ctype.h>
  38 #include <errno.h>
  39 #include <fcntl.h>
  40 #include <limits.h>
  41 #include <pwd.h>
  42 #include <signal.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <unistd.h>
  46 #include <getopt.h>
  47 #include <linux/if_slip.h>
  48
  49 #if defined(__GLIBC__)
  50 #if __GLIBC__ == 2 && __GLIBC_MINOR__ == 0
  51 # include <termbits.h>
  52 #else
  53 # include <termios.h>
  54 #endif
  55 #endif
  56
  57 #include "pathnames.h"
  58 #include "net-support.h"
  59 #include "version.h"
  60 #include "config.h"
  61 #include "intl.h"
  62 #include "util.h"
  63
  64 #ifndef _PATH_LOCKD
  65 #define _PATH_LOCKD             "/var/lock"             /* lock files   */
  66 #endif
  67 #ifndef _UID_UUCP
  68 #define _UID_UUCP               "uucp"                  /* owns locks   */
  69 #endif
  70
  71
  72 #define DEF_PROTO       "cslip"
  73
  74
  75 const char *Release = RELEASE,
  76            *Version = "@(#) slattach 1.21 (1999-11-21)",
  77            *Signature = "net-tools, Fred N. van Kempen et al.";
  78
  79
  80 struct {
  81   const char    *speed;
  82   int   code;
  83 } tty_speeds[] = {                      /* table of usable baud rates   */
  84   { "50",       B50     }, { "75",      B75     },
  85   { "110",      B110    }, { "300",     B300    },
  86   { "600",      B600    }, { "1200",    B1200   },
  87   { "2400",     B2400   }, { "4800",    B4800   },
  88   { "9600",     B9600   },
  89 #ifdef B14400
  90   { "14400",    B14400  },
  91 #endif
  92 #ifdef B19200
  93   { "19200",    B19200  },
  94 #endif
  95 #ifdef B38400
  96   { "38400",    B38400  },
  97 #endif
  98 #ifdef B57600
  99   { "57600",    B57600  },
 100 #endif
 101 #ifdef B115200
 102   { "115200",   B115200 },
 103 #endif
 104   { NULL,       0       }
 105 };
 106 struct termios  tty_saved,              /* saved TTY device state       */
 107                 tty_current;            /* current TTY device state     */
 108 int             tty_sdisc,              /* saved TTY line discipline    */
 109                 tty_ldisc,              /* current TTY line discipline  */
 110                 tty_fd = -1;            /* TTY file descriptor          */
 111 int             opt_c = 0;              /* "command" to run at exit     */
 112 int             opt_e = 0;              /* "activate only" flag         */
 113 int             opt_h = 0;              /* "hangup" on carrier loss     */
 114 #ifdef SIOCSKEEPALIVE
 115 int             opt_k = 0;              /* "keepalive" value            */
 116 #endif
 117 int             opt_l = 0;              /* "lock it" flag               */
 118 int             opt_L = 0;              /* clocal flag                  */
 119 int             opt_m = 0;              /* "set RAW mode" flag          */
 120 int             opt_n = 0;              /* "set No Mesg" flag           */
 121 #ifdef SIOCSOUTFILL
 122 int             opt_o = 0;              /* "outfill" value              */
 123 #endif
 124 int             opt_q = 0;              /* "quiet" flag                 */
 125 int             opt_d = 0;              /* debug flag                   */
 126 int             opt_v = 0;              /* Verbose flag                 */
 127
 128 /* Disable any messages to the input channel of this process. */
 129 static int
 130 tty_nomesg(int fd)
 131 {
 132   if (opt_n == 0) return(0);
 133   return(fchmod(fd, 0600));
 134 }
 135
 136 /* Check for an existing lock file on our device */
 137 static int
 138 tty_already_locked(char *nam)
 139 {
 140   int  i = 0, pid = 0;
 141   FILE *fd = (FILE *)0;
 142
 143   /* Does the lock file on our device exist? */
 144   if ((fd = fopen(nam, "r")) == (FILE *)0)
 145     return(0); /* No, return perm to continue */
 146
 147   /* Yes, the lock is there.  Now let's make sure */
 148   /* at least there's no active process that owns */
 149   /* that lock.                                   */
 150   i = fscanf(fd, "%d", &pid);
 151   (void) fclose(fd);
 152
 153   if (i != 1) /* Lock file format's wrong! Kill't */
 154     return(0);
 155
 156   /* We got the pid, check if the process's alive */
 157   if (kill(pid, 0) == 0)      /* it found process */
 158       return(1);          /* Yup, it's running... */
 159
 160   /* Dead, we can proceed locking this device...  */
 161   return(0);
 162 }
 163
 164 /* Lock or unlock a terminal line. */
 165 static int
 166 tty_lock(char *path, int mode)
 167 {
 168   static char saved_path[PATH_MAX];
 169   static int saved_lock = 0;
 170   struct passwd *pw;
 171   int fd;
 172   char apid[16];
 173
 174   /* We do not lock standard input. */
 175   if ((opt_l == 0) || ((path == NULL) && (saved_lock == 0))) return(0);
 176
 177   if (mode == 1) {      /* lock */
 178         sprintf(saved_path, "%s/LCK..%s", _PATH_LOCKD, path);
 179         if (tty_already_locked(saved_path)) {
 180                 fprintf(stderr, _("slattach: /dev/%s already locked!\n"), path);
 181                 return(-1);
 182         }
 183         if ((fd = creat(saved_path, 0644)) < 0) {
 184                 if (errno != EEXIST)
 185                         if (opt_q == 0) fprintf(stderr,
 186                                 _("slattach: tty_lock: (%s): %s\n"),
 187                                         saved_path, strerror(errno));
 188                 return(-1);
 189         }
 190         sprintf(apid, "%10d\n", getpid());
 191         if (write(fd, apid, strlen(apid)) != strlen(apid)) {
 192                 fprintf(stderr, _("slattach: cannot write PID file\n"));
 193                 close(fd);
 194                 unlink(saved_path);
 195                 return(-1);
 196         }
 197
 198         (void) close(fd);
 199
 200         /* Make sure UUCP owns the lockfile.  Required by some packages. */
 201         if ((pw = getpwnam(_UID_UUCP)) == NULL) {
 202                 if (opt_q == 0) fprintf(stderr, _("slattach: tty_lock: UUCP user %s unknown!\n"),
 203                                         _UID_UUCP);
 204                 return(0);      /* keep the lock anyway */
 205         }
 206         (void) chown(saved_path, pw->pw_uid, pw->pw_gid);
 207         saved_lock = 1;
 208   } else {      /* unlock */
 209         if (saved_lock != 1) return(0);
 210         if (unlink(saved_path) < 0) {
 211                 if (opt_q == 0) fprintf(stderr,
 212                         "slattach: tty_unlock: (%s): %s\n", saved_path,
 213                                                         strerror(errno));
 214                 return(-1);
 215         }
 216         saved_lock = 0;
 217   }
 218
 219   return(0);
 220 }
 221
 222
 223 /* Find a serial speed code in the table. */
 224 static int
 225 tty_find_speed(const char *speed)
 226 {
 227   int i;
 228
 229   i = 0;
 230   while (tty_speeds[i].speed != NULL) {
 231         if (!strcmp(tty_speeds[i].speed, speed)) return(tty_speeds[i].code);
 232         i++;
 233   }
 234   return(-EINVAL);
 235 }
 236
 237
 238 /* Set the number of stop bits. */
 239 static int
 240 tty_set_stopbits(struct termios *tty, char *stopbits)
 241 {
 242   if (opt_d) printf("slattach: tty_set_stopbits: %c\n", *stopbits);
 243   switch(*stopbits) {
 244         case '1':
 245                 tty->c_cflag &= ~CSTOPB;
 246                 break;
 247
 248         case '2':
 249                 tty->c_cflag |= CSTOPB;
 250                 break;
 251
 252         default:
 253                 return(-EINVAL);
 254   }
 255   return(0);
 256 }
 257
 258
 259 /* Set the number of data bits. */
 260 static int
 261 tty_set_databits(struct termios *tty, char *databits)
 262 {
 263   if (opt_d) printf("slattach: tty_set_databits: %c\n", *databits);
 264   tty->c_cflag &= ~CSIZE;
 265   switch(*databits) {
 266         case '5':
 267                 tty->c_cflag |= CS5;
 268                 break;
 269
 270         case '6':
 271                 tty->c_cflag |= CS6;
 272                 break;
 273
 274         case '7':
 275                 tty->c_cflag |= CS7;
 276                 break;
 277
 278         case '8':
 279                 tty->c_cflag |= CS8;
 280                 break;
 281
 282         default:
 283                 return(-EINVAL);
 284   }
 285   return(0);
 286 }
 287
 288
 289 /* Set the type of parity encoding. */
 290 static int
 291 tty_set_parity(struct termios *tty, char *parity)
 292 {
 293   if (opt_d) printf("slattach: tty_set_parity: %c\n", *parity);
 294   switch(toupper(*parity)) {
 295         case 'N':
 296                 tty->c_cflag &= ~(PARENB | PARODD);
 297                 break;
 298
 299         case 'O':
 300                 tty->c_cflag &= ~(PARENB | PARODD);
 301                 tty->c_cflag |= (PARENB | PARODD);
 302                 break;
 303
 304         case 'E':
 305                 tty->c_cflag &= ~(PARENB | PARODD);
 306                 tty->c_cflag |= (PARENB);
 307                 break;
 308
 309         default:
 310                 return(-EINVAL);
 311   }
 312   return(0);
 313 }
 314
 315
 316 /* Set the line speed of a terminal line. */
 317 static int
 318 tty_set_speed(struct termios *tty, const char *speed)
 319 {
 320   int code;
 321
 322   if (opt_d) printf("slattach: tty_set_speed: %s\n", speed);
 323   if ((code = tty_find_speed(speed)) < 0) return(code);
 324   tty->c_cflag &= ~CBAUD;
 325   tty->c_cflag |= code;
 326   return(0);
 327 }
 328
 329
 330 /* Put a terminal line in a transparent state. */
 331 static int
 332 tty_set_raw(struct termios *tty)
 333 {
 334   int i;
 335   int speed;
 336
 337   for(i = 0; i < NCCS; i++)
 338                 tty->c_cc[i] = '\0';            /* no spec chr          */
 339   tty->c_cc[VMIN] = 1;
 340   tty->c_cc[VTIME] = 0;
 341   tty->c_iflag = (IGNBRK | IGNPAR);             /* input flags          */
 342   tty->c_oflag = (0);                           /* output flags         */
 343   tty->c_lflag = (0);                           /* local flags          */
 344   speed = (tty->c_cflag & CBAUD);               /* save current speed   */
 345   tty->c_cflag = (CRTSCTS | HUPCL | CREAD);     /* UART flags           */
 346   if (opt_L)
 347         tty->c_cflag |= CLOCAL;
 348   tty->c_cflag |= speed;                        /* restore speed        */
 349   return(0);
 350 }
 351
 352
 353 /* Fetch the state of a terminal. */
 354 static int
 355 tty_get_state(struct termios *tty)
 356 {
 357   if (ioctl(tty_fd, TCGETS, tty) < 0) {
 358         if (opt_q == 0) fprintf(stderr,
 359                 "slattach: tty_get_state: %s\n", strerror(errno));
 360         return(-errno);
 361   }
 362   return(0);
 363 }
 364
 365
 366 /* Set the state of a terminal. */
 367 static int
 368 tty_set_state(struct termios *tty)
 369 {
 370   if (ioctl(tty_fd, TCSETS, tty) < 0) {
 371         if (opt_q == 0) fprintf(stderr,
 372                 "slattach: tty_set_state: %s\n", strerror(errno));
 373         return(-errno);
 374   }
 375   return(0);
 376 }
 377
 378
 379 /* Get the line discipline of a terminal line. */
 380 static int
 381 tty_get_disc(int *disc)
 382 {
 383   if (ioctl(tty_fd, TIOCGETD, disc) < 0) {
 384         if (opt_q == 0) fprintf(stderr,
 385                 "slattach: tty_get_disc: %s\n", strerror(errno));
 386         return(-errno);
 387   }
 388   return(0);
 389 }
 390
 391
 392 /* Set the line discipline of a terminal line. */
 393 static int
 394 tty_set_disc(int disc)
 395 {
 396   if (disc == -1) disc = tty_sdisc;
 397
 398   if (ioctl(tty_fd, TIOCSETD, &disc) < 0) {
 399         if (opt_q == 0) fprintf(stderr,
 400                 "slattach: tty_set_disc(%d, %d): %s\n", tty_fd,
 401                         disc, strerror(errno));
 402         return(-errno);
 403   }
 404   return(0);
 405 }
 406
 407
 408 /* Fetch the name of the network interface attached to this terminal. */
 409 static int
 410 tty_get_name(char *name)
 411 {
 412   if (ioctl(tty_fd, SIOCGIFNAME, name) < 0) {
 413         if (opt_q == 0)
 414             perror("tty_get_name");
 415         return(-errno);
 416   }
 417   return(0);
 418 }
 419
 420
 421 /* Hangup the line. */
 422 static int
 423 tty_hangup(void)
 424 {
 425   struct termios tty;
 426
 427   tty = tty_current;
 428   (void) tty_set_speed(&tty, "0");
 429   if (tty_set_state(&tty) < 0) {
 430         if (opt_q == 0) fprintf(stderr, _("slattach: tty_hangup(DROP): %s\n"), strerror(errno));
 431         return(-errno);
 432   }
 433
 434   (void) sleep(1);
 435
 436   if (tty_set_state(&tty_current) < 0) {
 437         if (opt_q == 0) fprintf(stderr, _("slattach: tty_hangup(RAISE): %s\n"), strerror(errno));
 438         return(-errno);
 439   }
 440   return(0);
 441 }
 442
 443
 444 /* Close down a terminal line. */
 445 static int
 446 tty_close(void)
 447 {
 448   (void) tty_set_disc(tty_sdisc);
 449   (void) tty_hangup();
 450   (void) tty_lock(NULL, 0);
 451   return(0);
 452 }
 453
 454
 455 /* Open and initialize a terminal line. */
 456 static int
 457 tty_open(char *name, const char *speed)
 458 {
 459   char pathbuf[PATH_MAX];
 460   register char *path_open, *path_lock;
 461   int fd;
 462
 463   /* Try opening the TTY device. */
 464   if (name != NULL) {
 465         if (name[0] != '/') {
 466                 if (strlen(name + 6) > sizeof(pathbuf)) {
 467                         if (opt_q == 0) fprintf(stderr,
 468                                 _("slattach: tty name too long\n"));
 469                         return (-1);
 470                 }
 471                 sprintf(pathbuf, "/dev/%s", name);
 472                 path_open = pathbuf;
 473                 path_lock = name;
 474         } else if (!strncmp(name, "/dev/", 5)) {
 475                 path_open = name;
 476                 path_lock = name + 5;
 477         } else {
 478                 path_open = name;
 479                 path_lock = name;
 480         }
 481         if (opt_d) printf("slattach: tty_open: looking for lock\n");
 482         if (tty_lock(path_lock, 1)) return(-1); /* can we lock the device? */
 483         if (opt_d) printf("slattach: tty_open: trying to open %s\n", path_open);
 484         if ((fd = open(path_open, O_RDWR|O_NDELAY)) < 0) {
 485                 if (opt_q == 0) fprintf(stderr,
 486                         "slattach: tty_open(%s, RW): %s\n",
 487                                         path_open, strerror(errno));
 488                 return(-errno);
 489         }
 490         tty_fd = fd;
 491         if (opt_d) printf("slattach: tty_open: %s (fd=%d) ", path_open, fd);
 492   } else {
 493         tty_fd = 0;
 494   }
 495
 496   /* Fetch the current state of the terminal. */
 497   if (tty_get_state(&tty_saved) < 0) {
 498         if (opt_q == 0) fprintf(stderr, _("slattach: tty_open: cannot get current state!\n"));
 499         return(-errno);
 500   }
 501   tty_current = tty_saved;
 502
 503   /* Fetch the current line discipline of this terminal. */
 504   if (tty_get_disc(&tty_sdisc) < 0) {
 505         if (opt_q == 0) fprintf(stderr, _("slattach: tty_open: cannot get current line disc!\n"));
 506         return(-errno);
 507   }
 508   tty_ldisc = tty_sdisc;
 509
 510   /* Put this terminal line in a 8-bit transparent mode. */
 511   if (opt_m == 0) {
 512         if (tty_set_raw(&tty_current) < 0) {
 513                 if (opt_q == 0) fprintf(stderr, _("slattach: tty_open: cannot set RAW mode!\n"));
 514                 return(-errno);
 515         }
 516
 517         /* Set the default speed if we need to. */
 518         if (speed != NULL) {
 519                 if (tty_set_speed(&tty_current, speed) != 0) {
 520                         if (opt_q == 0) fprintf(stderr, _("slattach: tty_open: cannot set %s bps!\n"),
 521                                                 speed);
 522                         return(-errno);
 523                 }
 524         }
 525
 526         /* Set up a completely 8-bit clean line. */
 527         if (tty_set_databits(&tty_current, "8") ||
 528             tty_set_stopbits(&tty_current, "1") ||
 529             tty_set_parity(&tty_current, "N")) {
 530                 if (opt_q == 0) fprintf(stderr, _("slattach: tty_open: cannot set 8N1 mode!\n"));
 531                 return(-errno);
 532         }
 533
 534         /* Set the new line mode. */
 535         if ((fd = tty_set_state(&tty_current)) < 0) return(fd);
 536   }
 537
 538   /* OK, line is open.  Do we need to "silence" it? */
 539   (void) tty_nomesg(tty_fd);
 540
 541   return(0);
 542 }
 543
 544
 545 /* Catch any signals. */
 546 static void
 547 sig_catch(int sig)
 548 {
 549 /*  (void) signal(sig, sig_catch); */
 550   tty_close();
 551   exit(0);
 552 }
 553
 554
 555 static void
 556 usage(void)
 557 {
 558   char *usage_msg = "Usage: slattach [-ehlLmnqv] "
 559 #ifdef SIOCSKEEPALIVE
 560           "[-k keepalive] "
 561 #endif
 562 #ifdef SIOCSOUTFILL
 563           "[-o outfill] "
 564 #endif
 565           "[-c cmd] [-s speed] [-p protocol] tty | -\n"
 566           "       slattach -V | --version\n";
 567
 568   fprintf(stderr, usage_msg);
 569   exit(1);
 570 }
 571
 572
 573 static void
 574 version(void)
 575 {
 576     printf("%s\n%s\n%s\n", Release, Version, Signature);
 577     exit(E_VERSION);
 578 }
 579
 580
 581 int
 582 main(int argc, char *argv[])
 583 {
 584   char path_buf[128];
 585   char *path_dev;
 586   char buff[128];
 587   const char *speed = NULL;
 588   const char *proto = DEF_PROTO;
 589   const char *extcmd = NULL;
 590   int s;
 591   static struct option longopts[] = {
 592     { "version", 0, NULL, 'V' },
 593     { NULL, 0, NULL, 0 }
 594   };
 595
 596   strcpy(path_buf, "");
 597   path_dev = path_buf;
 598
 599   /* Scan command line for any arguments. */
 600   opterr = 0;
 601   while ((s = getopt_long(argc, argv, "c:ehlLmnp:qs:vdVk:o:", longopts, NULL)) != EOF) switch(s) {
 602         case 'c':
 603                 extcmd = optarg;
 604                 break;
 605
 606         case 'e':
 607                 opt_e = 1 - opt_e;
 608                 break;
 609
 610         case 'h':
 611                 opt_h = 1 - opt_h;
 612                 break;
 613
 614 #ifdef SIOCSKEEPALIVE
 615         case 'k':
 616                 opt_k = atoi(optarg);
 617                 break;
 618 #endif
 619
 620         case 'L':
 621                 opt_L = 1 - opt_L;
 622                 break;
 623
 624         case 'l':
 625                 opt_l = 1 - opt_l;
 626                 break;
 627
 628         case 'm':
 629                 opt_m = 1 - opt_m;
 630                 break;
 631
 632         case 'n':
 633                 opt_n = 1 - opt_n;
 634                 break;
 635
 636 #ifdef SIOCSOUTFILL
 637         case 'o':
 638                 opt_o = atoi(optarg);
 639                 break;
 640 #endif
 641
 642         case 'p':
 643                 proto = optarg;
 644                 break;
 645
 646         case 'q':
 647                 opt_q = 1 - opt_q;
 648                 break;
 649
 650         case 's':
 651                 speed = optarg;
 652                 break;
 653
 654         case 'd':
 655                 opt_d = 1 - opt_d;
 656                 break;
 657
 658         case 'v':
 659                 opt_v = 1 - opt_v;
 660                 break;
 661
 662         case 'V':
 663                 version();
 664                 /*NOTREACHED*/
 665
 666         default:
 667                 usage();
 668                 /*NOTREACHED*/
 669   }
 670
 671   if (setvbuf(stdout,0,_IOLBF,0)) {
 672         if (opt_q == 0) fprintf(stderr, _("slattach: setvbuf(stdout,0,_IOLBF,0) : %s\n"),
 673                                 strerror(errno));
 674         exit(1);
 675   }
 676
 677   activate_init();
 678
 679   if (!strcmp(proto, "tty"))
 680        opt_m++;
 681
 682   /* Is a terminal given? */
 683   if (optind != (argc - 1)) usage();
 684   safe_strncpy(path_buf, argv[optind], sizeof(path_buf));
 685   if (!strcmp(path_buf, "-")) {
 686         opt_e = 1;
 687         path_dev = NULL;
 688         if (tty_open(NULL, speed) < 0) { return(3); }
 689   } else {
 690         path_dev = path_buf;
 691         if (tty_open(path_dev, speed) < 0) { return(3); }
 692   }
 693
 694   /* Start the correct protocol. */
 695   if (!strcmp(proto, "tty")) {
 696         tty_sdisc = N_TTY;
 697         tty_close();
 698         return(0);
 699   }
 700   if (activate_ld(proto, tty_fd))
 701         return(1);
 702   if ((opt_v == 1) || (opt_d == 1)) {
 703         if (tty_get_name(buff)) { return(3); }
 704         printf(_("%s started"), proto);
 705         if (path_dev != NULL) printf(_(" on %s"), path_dev);
 706         printf(_(" interface %s\n"), buff);
 707   }
 708
 709   /* Configure keepalive and outfill. */
 710 #ifdef SIOCSKEEPALIVE
 711   if (opt_k && (ioctl(tty_fd, SIOCSKEEPALIVE, &opt_k) < 0))
 712           fprintf(stderr, "slattach: ioctl(SIOCSKEEPALIVE): %s\n", strerror(errno));
 713 #endif
 714 #ifdef SIOCSOUTFILL
 715   if (opt_o && (ioctl(tty_fd, SIOCSOUTFILL, &opt_o) < 0))
 716           fprintf(stderr, "slattach: ioctl(SIOCSOUTFILL): %s\n", strerror(errno));
 717 #endif
 718
 719   (void) signal(SIGHUP, sig_catch);
 720   (void) signal(SIGINT, sig_catch);
 721   (void) signal(SIGQUIT, sig_catch);
 722   (void) signal(SIGTERM, sig_catch);
 723
 724   /* Wait until we get killed if hanging on a terminal. */
 725   if (opt_e == 0) {
 726         while(1) {
 727                 if(opt_h == 1) { /* hangup on carrier loss */
 728                         int n = 0;
 729
 730                         ioctl(tty_fd, TIOCMGET, &n);
 731                         if(!(n & TIOCM_CAR))
 732                                 break;
 733                         sleep(15);
 734                 }
 735                 else
 736                         sleep(60);
 737         };
 738
 739         tty_close();
 740         if(extcmd)      /* external command on exit */
 741                 system(extcmd);
 742   }
 743   exit(0);
 744 }