commands/term/term.c

   1 /* term - terminal simulator            Author: Andy Tanenbaum */
   2
   3 /* This program allows the user to turn a MINIX system into a dumb
   4  * terminal to communicate with a remote computer through one of the ttys.
   5  * It forks into two processes.  The parent sits in a tight loop copying
   6  * from stdin to the tty.  The child sits in a tight loop copying from
   7  * the tty to stdout.
   8  *
   9  * 2 Sept 88 BDE (Bruce D. Evans): Massive changes to make current settings the
  10  * default, allow any file as the "tty", support fancy baud rates and remove
  11  * references to and dependencies on modems and keyboards, so (e.g.)
  12  * a local login on /dev/tty1 can do an external login on /dev/tty2.
  13  *
  14  * 3 Sept 88 BDE: Split parent again to main process copies from stdin to a
  15  * pipe which is copied to the tty.  This stops a blocked write to the
  16  * tty from hanging the program.
  17  *
  18  * 11 Oct 88 BDE: Cleaned up baud rates and parity stripping.
  19  *
  20  * 09 Oct 90 MAT (Michael A. Temari): Fixed bug where terminal isn't reset
  21  * if an error occurs.
  22  *
  23  * Nov 90 BDE: Don't broadcast kill(0, SIGINT) since two or more of these
  24  * in a row will kill the parent shell.
  25  *
  26  * 19 Oct 89 RW (Ralf Wenk): Adapted to MINIX ST 1.1 + RS232 driver. Split
  27  * error into error_n and error. Added resetting of the terminal settings
  28  * in error.
  29  *
  30  * 24 Nov 90 RW: Adapted to MINIX ST 1.5.10.2. Forked processes are now
  31  * doing an exec to get a better performance. This idea is stolen from
  32  * a terminal program written by Felix Croes.
  33  *
  34  * 01 May 91 RW: Merged the MINIX ST patches with Andys current version.
  35  * Most of the 19 Oct 89 patches are deleted because they are already there.
  36  *
  37  * 10 Mar 96 KJB: Termios adaption, cleanup, command key interface.
  38  *
  39  * 27 Nov 96 KJB: Add -c flag that binds commands to keys.
  40  *
  41  * Example usage:
  42  *      term                    : baud, bits/char, parity from /dev/tty1
  43  *      term 9600 7 even        : 9600 baud, 7 bits/char, even parity
  44  *      term odd 300 7          :  300 baud, 7 bits/char, odd parity
  45  *      term /dev/tty2          : use /dev/tty2 rather than /dev/tty1
  46  *                              : Any argument starting with "/" is
  47  *                              : taken as the communication device.
  48  *      term 8 57600 /dev/tty2 -atdt4441234     : if an argument begins with
  49  *                                              : - , the rest of that arg is
  50  *                                              : sent to the modem as a
  51  *                                              : dial string
  52  */
  53
  54 #include <sys/types.h>
  55 #include <fcntl.h>
  56 #include <termios.h>
  57 #include <signal.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <unistd.h>
  61 #include <stdarg.h>
  62 #include <errno.h>
  63 #include <sys/wait.h>
  64 #include <sys/stat.h>
  65
  66 #define CHUNK 1024              /* how much to read at once */
  67
  68 char TERM_LINE[] = "/dev/modem";/* default serial port to use */
  69
  70                                 /* device lock file */
  71 char lockfile[] = "/usr/spool/locks/LK.iii.jjj.kkk";
  72
  73 char *commdev;                  /* communications device a.k.a. "modem". */
  74 int commfd;                     /* open file no. for comm device */
  75 struct termios tccomm;          /* terminal parameters for commfd */
  76 struct termios tcstdin;         /* terminal parameters for stdin */
  77 struct termios tcsavestdin;     /* saved terminal parameters for stdin */
  78
  79 /* Special key to get term's attention. */
  80 #define HOTKEY  '\035'          /* CTRL-] */
  81
  82 struct param_s {
  83   char *pattern;
  84   unsigned value;
  85   enum { BAD, BITS, PARITY, SPEED } type;
  86 } params[] = {
  87   { "5",        CS5,            BITS    },
  88   { "6",        CS6,            BITS    },
  89   { "7",        CS7,            BITS    },
  90   { "8",        CS8,            BITS    },
  91
  92   { "even",     PARENB,         PARITY  },
  93   { "odd",      PARENB|PARODD,  PARITY  },
  94
  95   { "50",       B50,            SPEED   },
  96   { "75",       B75,            SPEED   },
  97   { "110",      B110,           SPEED   },
  98   { "134",      B134,           SPEED   },
  99   { "200",      B200,           SPEED   },
 100   { "300",      B300,           SPEED   },
 101   { "600",      B600,           SPEED   },
 102   { "1200",     B1200,          SPEED   },
 103   { "1800",     B1800,          SPEED   },
 104   { "2400",     B2400,          SPEED   },
 105   { "4800",     B4800,          SPEED   },
 106   { "9600",     B9600,          SPEED   },
 107   { "19200",    B19200,         SPEED   },
 108   { "38400",    B38400,         SPEED   },
 109   { "57600",    B57600,         SPEED   },
 110   { "115200",   B115200,        SPEED   },
 111   { "",         0,              BAD     },      /* BAD type to end list */
 112 };
 113
 114 #define NIL ((char *) NULL)             /* tell(fd, ..., NIL) */
 115
 116 int main(int argc, char *argv[]);
 117 int isdialstr(char *arg);
 118 void tell(int fd, ...);
 119 void reader(int on);
 120 void shell(char *cmd);
 121 void lock_device(char *device);
 122 void fatal(char *label);
 123 void setnum(char *s, int n);
 124 void set_uart(int argc, char *argv[], struct termios *tcp);
 125 void set_raw(struct termios *tcp);
 126 void quit(int code);
 127
 128 int main(argc, argv)
 129 int argc;
 130 char *argv[];
 131 {
 132   int i;
 133   unsigned char key;
 134   int candial;
 135
 136   for (i = 1; i < argc; ++i) {
 137         if (argv[i][0] == '/') {
 138                 if (commdev != NULL) {
 139                         tell(2, "term: too many communication devices\n", NIL);
 140                         exit(1);
 141                 }
 142                 commdev = argv[i];
 143         }
 144   }
 145   if (commdev == NULL) commdev = TERM_LINE;
 146
 147   /* Save tty attributes of the terminal. */
 148   if (tcgetattr(0, &tcsavestdin) < 0) {
 149         tell(2, "term: standard input is not a terminal\n", NIL);
 150         exit(1);
 151   }
 152
 153   lock_device(commdev);
 154
 155   commfd = open(commdev, O_RDWR);
 156   if (commfd < 0) {
 157         tell(2, "term: can't open ", commdev, ": ", strerror(errno), "\n", NIL);
 158         quit(1);
 159   }
 160
 161   /* Compute RAW modes of terminal and modem. */
 162   if (tcgetattr(commfd, &tccomm) < 0) {
 163         tell(2, "term: ", commdev, " is not a terminal\n", NIL);
 164         quit(1);
 165   }
 166   signal(SIGINT, quit);
 167   signal(SIGTERM, quit);
 168   tcstdin = tcsavestdin;
 169   set_raw(&tcstdin);
 170   set_raw(&tccomm);
 171   set_uart(argc, argv, &tccomm);
 172   tcsetattr(0, TCSANOW, &tcstdin);
 173   tcsetattr(commfd, TCSANOW, &tccomm);
 174
 175   /* Start a reader process to copy modem output to the screen. */
 176   reader(1);
 177
 178   /* Welcome message. */
 179   tell(1, "Connected to ", commdev,
 180                         ", command key is CTRL-], type ^]? for help\r\n", NIL);
 181
 182   /* Dial. */
 183   candial = 0;
 184   for (i = 1; i < argc; ++i) {
 185         if (!isdialstr(argv[i])) continue;
 186         tell(commfd, argv[i] + 1, "\r", NIL);
 187         candial = 1;
 188   }
 189
 190   /* Main loop of the terminal simulator. */
 191   while (read(0, &key, 1) == 1) {
 192         if (key == HOTKEY) {
 193                 /* Command key typed. */
 194                 if (read(0, &key, 1) != 1) continue;
 195
 196                 switch (key) {
 197                 default:
 198                         /* Added command? */
 199                         for (i = 1; i < argc; ++i) {
 200                                 char *arg = argv[i];
 201
 202                                 if (arg[0] == '-' && arg[1] == 'c'
 203                                                         && arg[2] == key) {
 204                                         reader(0);
 205                                         tcsetattr(0, TCSANOW, &tcsavestdin);
 206                                         shell(arg+3);
 207                                         tcsetattr(0, TCSANOW, &tcstdin);
 208                                         reader(1);
 209                                         break;
 210                                 }
 211                         }
 212                         if (i < argc) break;
 213
 214                         /* Unrecognized command, print list. */
 215                         tell(1, "\r\nTerm commands:\r\n",
 216                                 " ? - this help\r\n",
 217                                 candial ? " d - redial\r\n" : "",
 218                                 " s - subshell (e.g. for file transfer)\r\n",
 219                                 " h - hangup (+++ ATH)\r\n",
 220                                 " b - send a break\r\n",
 221                                 " q - exit term\r\n",
 222                                 NIL);
 223                         for (i = 1; i < argc; ++i) {
 224                                 char *arg = argv[i];
 225                                 static char cmd[] = " x - ";
 226
 227                                 if (arg[0] == '-' && arg[1] == 'c'
 228                                                         && arg[2] != 0) {
 229                                         cmd[1] = arg[2];
 230                                         tell(1, cmd, arg+3, "\r\n", NIL);
 231                                 }
 232                         }
 233                         tell(1, "^] - send a CTRL-]\r\n\n",
 234                                 NIL);
 235                         break;
 236                 case 'd':
 237                         /* Redial by sending the dial commands again. */
 238                         for (i = 1; i < argc; ++i) {
 239                                 if (!isdialstr(argv[i])) continue;
 240                                 tell(commfd, argv[i] + 1, "\r", NIL);
 241                         }
 242                         break;
 243                 case 's':
 244                         /* Subshell. */
 245                         reader(0);
 246                         tcsetattr(0, TCSANOW, &tcsavestdin);
 247                         shell(NULL);
 248                         tcsetattr(0, TCSANOW, &tcstdin);
 249                         reader(1);
 250                         break;
 251                 case 'h':
 252                         /* Hangup by using the +++ escape and ATH command. */
 253                         sleep(2);
 254                         tell(commfd, "+++", NIL);
 255                         sleep(2);
 256                         tell(commfd, "ATH\r", NIL);
 257                         break;
 258                 case 'b':
 259                         /* Send a break. */
 260                         tcsendbreak(commfd, 0);
 261                         break;
 262                 case 'q':
 263                         /* Exit term. */
 264                         quit(0);
 265                 case HOTKEY:
 266                         (void) write(commfd, &key, 1);
 267                         break;
 268                 }
 269         } else {
 270                 /* Send keyboard input down the serial line. */
 271                 if (write(commfd, &key, 1) != 1) break;
 272         }
 273   }
 274   tell(2, "term: nothing to copy from input to ", commdev, "?\r\n", NIL);
 275   quit(1);
 276 }
 277
 278
 279 int isdialstr(char *arg)
 280 {
 281 /* True iff arg is the start of a dial string, i.e. "-at...". */
 282
 283   return (arg[0] == '-'
 284         && (arg[1] == 'a' || arg[1] == 'A')
 285         && (arg[2] == 't' || arg[2] == 'T'));
 286 }
 287
 288
 289 void tell(int fd, ...)
 290 {
 291 /* Write strings to file descriptor 'fd'. */
 292   va_list ap;
 293   char *s;
 294
 295   va_start(ap, fd);
 296   while ((s = va_arg(ap, char *)) != NIL) write(fd, s, strlen(s));
 297   va_end(ap);
 298 }
 299
 300
 301 void reader(on)
 302 int on;
 303 {
 304 /* Start or end a process that copies from the modem to the screen. */
 305
 306   static pid_t pid;
 307   char buf[CHUNK];
 308   ssize_t n, m, r;
 309
 310   if (!on) {
 311         /* End the reader process (if any). */
 312         if (pid == 0) return;
 313         kill(pid, SIGKILL);
 314         (void) waitpid(pid, (int *) NULL, 0);
 315         pid = 0;
 316         return;
 317   }
 318
 319   /* Start a reader */
 320   pid = fork();
 321   if (pid < 0) {
 322         tell(2, "term: fork() failed: ", strerror(errno), "\r\n", NIL);
 323         quit(1);
 324   }
 325   if (pid == 0) {
 326         /* Child: Copy from the modem to the screen. */
 327
 328         while ((n = read(commfd, buf, sizeof(buf))) > 0) {
 329                 m = 0;
 330                 while (m < n && (r = write(1, buf + m, n - m)) > 0) m += r;
 331         }
 332         tell(2, "term: nothing to copy from ", commdev, " to output?\r\n", NIL);
 333         kill(getppid(), SIGTERM);
 334         _exit(1);
 335   }
 336   /* One reader on the loose. */
 337 }
 338
 339
 340 void shell(char *cmd)
 341 {
 342 /* Invoke a subshell to allow one to run zmodem for instance.  Run sh -c 'cmd'
 343  * instead if 'cmd' non-null.
 344  */
 345
 346   pid_t pid;
 347   char *shell, *sh0;
 348   void(*isav) (int);
 349   void(*qsav) (int);
 350   void(*tsav) (int);
 351
 352   if (cmd == NULL) {
 353         tell(1, "\nExit the shell to return to term, ",
 354                 commdev, " is open on file descriptor 9.\n", NIL);
 355   }
 356
 357   if (cmd != NULL || (shell = getenv("SHELL")) == NULL) shell = "/bin/sh";
 358   if ((sh0 = strrchr(shell, '/')) == NULL) sh0 = shell; else sh0++;
 359
 360   /* Start a shell */
 361   pid = fork();
 362   if (pid < 0) {
 363         tell(2, "term: fork() failed: ", strerror(errno), "\n", NIL);
 364         return;
 365   }
 366   if (pid == 0) {
 367         /* Child: Exec the shell. */
 368         setgid(getgid());
 369         setuid(getuid());
 370
 371         if (commfd != 9) { dup2(commfd, 9); close(commfd); }
 372
 373         if (cmd == NULL) {
 374                 execl(shell, sh0, (char *) NULL);
 375         } else {
 376                 execl(shell, sh0, "-c", cmd, (char *) NULL);
 377         }
 378         tell(2, "term: can't execute ", shell, ": ", strerror(errno), "\n",NIL);
 379         _exit(1);
 380   }
 381   /* Wait for the shell to exit. */
 382   isav = signal(SIGINT, SIG_IGN);
 383   qsav = signal(SIGQUIT, SIG_IGN);
 384   tsav = signal(SIGTERM, SIG_IGN);
 385   (void) waitpid(pid, (int *) 0, 0);
 386   (void) signal(SIGINT, isav);
 387   (void) signal(SIGQUIT, qsav);
 388   (void) signal(SIGTERM, tsav);
 389   tell(1, "\n[back to term]\n", NIL);
 390 }
 391
 392
 393 void lock_device(device)
 394 char *device;
 395 {
 396 /* Lock a device by creating a lock file using SYSV style locking. */
 397
 398   struct stat stbuf;
 399   unsigned int pid;
 400   int fd;
 401   int n;
 402   int u;
 403
 404   if (stat(device, &stbuf) < 0) fatal(device);
 405
 406   if (!S_ISCHR(stbuf.st_mode)) {
 407         tell(2, "term: ", device, " is not a character device\n", NIL);
 408         exit(1);
 409   }
 410
 411   /* Compute the lock file name. */
 412   setnum(lockfile + 23, (stbuf.st_dev >> 8) & 0xFF);    /* FS major (why?) */
 413   setnum(lockfile + 27, (stbuf.st_rdev >> 8) & 0xFF);   /* device major */
 414   setnum(lockfile + 31, (stbuf.st_rdev >> 0) & 0xFF);   /* device minor */
 415
 416   /* Try to make a lock file and put my pid in it. */
 417   u = umask(0);
 418   for (;;) {
 419         if ((fd = open(lockfile, O_RDONLY)) < 0) {
 420                 /* No lock file, try to lock it myself. */
 421                 if (errno != ENOENT) fatal(device);
 422                 if ((fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, 0444)) < 0) {
 423                         if (errno == EEXIST) continue;
 424                         fatal(lockfile);
 425                 }
 426                 pid = getpid();
 427                 n = write(fd, &pid, sizeof(pid));
 428                 if (n < 0) {
 429                         n = errno;
 430                         (void) unlink(lockfile);
 431                         errno = n;
 432                         fatal(lockfile);
 433                 }
 434                 close(fd);
 435                 break;
 436         } else {
 437                 /* Already there, but who owns it? */
 438                 n = read(fd, &pid, sizeof(pid));
 439                 if (n < 0) fatal(device);
 440                 close(fd);
 441                 if (n == sizeof(pid) && !(kill(pid, 0) < 0 && errno == ESRCH)) {
 442                         /* It is locked by a running process. */
 443                         tell(2, "term: ", device,
 444                                 " is in use by another program\n", NIL);
 445                         if (getpgrp() == getpid()) sleep(3);
 446                         exit(1);
 447                 }
 448                 /* Stale lock. */
 449                 tell(1, "Removing stale lock ", lockfile, "\n", NIL);
 450                 if (unlink(lockfile) < 0 && errno != ENOENT) fatal(lockfile);
 451         }
 452   }
 453   /* Lock achieved, but what if two terms encounters a stale lock at the same
 454    * time?
 455    */
 456   umask(u);
 457 }
 458
 459
 460 void fatal(char *label)
 461 {
 462   tell(2, "term: ", label, ": ", strerror(errno), "\n", NIL);
 463   exit(1);
 464 }
 465
 466
 467 void setnum(char *s, int n)
 468 {
 469 /* Poke 'n' into string 's' backwards as three decimal digits. */
 470   int i;
 471
 472   for (i = 0; i < 3; i++) { *--s = '0' + (n % 10); n /= 10; }
 473 }
 474
 475
 476 void set_uart(argc, argv, tcp)
 477 int argc;
 478 char *argv[];
 479 struct termios *tcp;
 480 {
 481 /* Set up the UART parameters. */
 482
 483   int i;
 484   char *arg;
 485   struct param_s *param;
 486
 487   /* Examine all the parameters and check for validity. */
 488   for (i = 1; i < argc; ++i) {
 489         arg = argv[i];
 490         if (arg[0] == '/' || arg[0] == '-') continue;
 491
 492         /* Check parameter for legality. */
 493         for (param = &params[0];
 494              param->type != BAD && strcmp(arg, param->pattern) != 0;
 495              ++param);
 496         switch (param->type) {
 497             case BAD:
 498                 tell(2, "Invalid parameter: ", arg, "\n", NIL);
 499                 quit(1);
 500                 break;
 501             case BITS:
 502                 tcp->c_cflag &= ~CSIZE;
 503                 tcp->c_cflag |= param->value;
 504                 break;
 505             case PARITY:
 506                 tcp->c_cflag &= PARENB | PARODD;
 507                 tcp->c_cflag |= param->value;
 508                 break;
 509             case SPEED:
 510                 cfsetispeed(tcp, (speed_t) param->value);
 511                 cfsetospeed(tcp, (speed_t) param->value);
 512                 break;
 513         }
 514   }
 515 }
 516
 517
 518 void set_raw(tcp)
 519 struct termios *tcp;
 520 {
 521   /* Set termios attributes for RAW mode. */
 522
 523   tcp->c_iflag &= ~(ICRNL|IGNCR|INLCR|IXON|IXOFF);
 524   tcp->c_lflag &= ~(ICANON|IEXTEN|ISIG|ECHO|ECHONL);
 525   tcp->c_oflag &= ~(OPOST);
 526   tcp->c_cc[VMIN] = 1;
 527   tcp->c_cc[VTIME] = 0;
 528 }
 529
 530
 531 void quit(code)
 532 int code;
 533 {
 534 /* Stop the reader process, reset the terminal, and exit. */
 535   reader(0);
 536   tcsetattr(0, TCSANOW, &tcsavestdin);
 537   (void) unlink(lockfile);
 538   exit(code);
 539 }