drivers/char/n_tty.c

   1 /*
   2  * n_tty.c --- implements the N_TTY line discipline.
   3  *
   4  * This code used to be in tty_io.c, but things are getting hairy
   5  * enough that it made sense to split things off.  (The N_TTY
   6  * processing has changed so much that it's hardly recognizable,
   7  * anyway...)
   8  *
   9  * Note that the open routine for N_TTY is guaranteed never to return
  10  * an error.  This is because Linux will fall back to setting a line
  11  * to N_TTY if it can not switch to any other line discipline.
  12  *
  13  * Written by Theodore Ts'o, Copyright 1994.
  14  *
  15  * This file also contains code originally written by Linus Torvalds,
  16  * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
  17  *
  18  * This file may be redistributed under the terms of the GNU Public
  19  * License.
  20  */
  21
  22 #include <linux/types.h>
  23 #include <linux/major.h>
  24 #include <linux/errno.h>
  25 #include <linux/signal.h>
  26 #include <linux/fcntl.h>
  27 #include <linux/sched.h>
  28 #include <linux/interrupt.h>
  29 #include <linux/tty.h>
  30 #include <linux/timer.h>
  31 #include <linux/ctype.h>
  32 #include <linux/kd.h>
  33 #include <linux/mm.h>
  34 #include <linux/string.h>
  35 #include <linux/malloc.h>
  36 #include <linux/poll.h>
  37
  38 #include <asm/uaccess.h>
  39 #include <asm/system.h>
  40 #include <asm/bitops.h>
  41
  42 #define CONSOLE_DEV MKDEV(TTY_MAJOR,0)
  43 #define SYSCONS_DEV  MKDEV(TTYAUX_MAJOR,1)
  44
  45 #ifndef MIN
  46 #define MIN(a,b)        ((a) < (b) ? (a) : (b))
  47 #endif
  48
  49 /* number of characters left in xmit buffer before select has we have room */
  50 #define WAKEUP_CHARS 256
  51
  52 /*
  53  * This defines the low- and high-watermarks for throttling and
  54  * unthrottling the TTY driver.  These watermarks are used for
  55  * controlling the space in the read buffer.
  56  */
  57 #define TTY_THRESHOLD_THROTTLE          128 /* now based on remaining room */
  58 #define TTY_THRESHOLD_UNTHROTTLE        128
  59
  60 static inline void put_tty_queue(unsigned char c, struct tty_struct *tty)
  61 {
  62         if (tty->read_cnt < N_TTY_BUF_SIZE) {
  63                 tty->read_buf[tty->read_head] = c;
  64                 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
  65                 tty->read_cnt++;
  66         }
  67 }
  68
  69 /*
  70  * Check whether to call the driver.unthrottle function.
  71  * We test the TTY_THROTTLED bit first so that it always
  72  * indicates the current state.
  73  */
  74 static void check_unthrottle(struct tty_struct * tty)
  75 {
  76         if (tty->count &&
  77             test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
  78             tty->driver.unthrottle)
  79                 tty->driver.unthrottle(tty);
  80 }
  81
  82 /*
  83  * Reset the read buffer counters, clear the flags,
  84  * and make sure the driver is unthrottled. Called
  85  * from n_tty_open() and n_tty_flush_buffer().
  86  */
  87 static void reset_buffer_flags(struct tty_struct *tty)
  88 {
  89         tty->read_head = tty->read_tail = tty->read_cnt = 0;
  90         tty->canon_head = tty->canon_data = tty->erasing = 0;
  91         memset(&tty->read_flags, 0, sizeof tty->read_flags);
  92         check_unthrottle(tty);
  93 }
  94
  95 /*
  96  * Flush the input buffer
  97  */
  98 void n_tty_flush_buffer(struct tty_struct * tty)
  99 {
 100         /* clear everything and unthrottle the driver */
 101         reset_buffer_flags(tty);
 102
 103         if (!tty->link)
 104                 return;
 105
 106         if (tty->link->packet) {
 107                 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
 108                 wake_up_interruptible(&tty->link->read_wait);
 109         }
 110 }
 111
 112 /*
 113  * Return number of characters buffered to be delivered to user
 114  */
 115 ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
 116 {
 117         if (tty->icanon) {
 118                 if (!tty->canon_data) return 0;
 119
 120                 return (tty->canon_head > tty->read_tail) ?
 121                         tty->canon_head - tty->read_tail :
 122                         tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
 123         }
 124         return tty->read_cnt;
 125 }
 126
 127 /*
 128  * Perform OPOST processing.  Returns -1 when the output device is
 129  * full and the character must be retried.
 130  */
 131 static int opost(unsigned char c, struct tty_struct *tty)
 132 {
 133         int     space, spaces;
 134
 135         space = tty->driver.write_room(tty);
 136         if (!space)
 137                 return -1;
 138
 139         if (O_OPOST(tty)) {
 140                 switch (c) {
 141                 case '\n':
 142                         if (O_ONLRET(tty))
 143                                 tty->column = 0;
 144                         if (O_ONLCR(tty)) {
 145                                 if (space < 2)
 146                                         return -1;
 147                                 tty->driver.put_char(tty, '\r');
 148                                 tty->column = 0;
 149                         }
 150                         tty->canon_column = tty->column;
 151                         break;
 152                 case '\r':
 153                         if (O_ONOCR(tty) && tty->column == 0)
 154                                 return 0;
 155                         if (O_OCRNL(tty)) {
 156                                 c = '\n';
 157                                 if (O_ONLRET(tty))
 158                                         tty->canon_column = tty->column = 0;
 159                                 break;
 160                         }
 161                         tty->canon_column = tty->column = 0;
 162                         break;
 163                 case '\t':
 164                         spaces = 8 - (tty->column & 7);
 165                         if (O_TABDLY(tty) == XTABS) {
 166                                 if (space < spaces)
 167                                         return -1;
 168                                 tty->column += spaces;
 169                                 tty->driver.write(tty, 0, "        ", spaces);
 170                                 return 0;
 171                         }
 172                         tty->column += spaces;
 173                         break;
 174                 case '\b':
 175                         if (tty->column > 0)
 176                                 tty->column--;
 177                         break;
 178                 default:
 179                         if (O_OLCUC(tty))
 180                                 c = toupper(c);
 181                         if (!iscntrl(c))
 182                                 tty->column++;
 183                         break;
 184                 }
 185         }
 186         tty->driver.put_char(tty, c);
 187         return 0;
 188 }
 189
 190 /*
 191  * opost_block --- to speed up block console writes, among other
 192  * things.
 193  */
 194 static ssize_t opost_block(struct tty_struct * tty,
 195                        const unsigned char * inbuf, unsigned int nr)
 196 {
 197         char    buf[80];
 198         int     space;
 199         int     i;
 200         char    *cp;
 201
 202         space = tty->driver.write_room(tty);
 203         if (!space)
 204                 return 0;
 205         if (nr > space)
 206                 nr = space;
 207         if (nr > sizeof(buf))
 208             nr = sizeof(buf);
 209         nr -= copy_from_user(buf, inbuf, nr);
 210         if (!nr)
 211                 return 0;
 212
 213         for (i = 0, cp = buf; i < nr; i++, cp++) {
 214                 switch (*cp) {
 215                 case '\n':
 216                         if (O_ONLRET(tty))
 217                                 tty->column = 0;
 218                         if (O_ONLCR(tty))
 219                                 goto break_out;
 220                         tty->canon_column = tty->column;
 221                         break;
 222                 case '\r':
 223                         if (O_ONOCR(tty) && tty->column == 0)
 224                                 goto break_out;
 225                         if (O_OCRNL(tty)) {
 226                                 *cp = '\n';
 227                                 if (O_ONLRET(tty))
 228                                         tty->canon_column = tty->column = 0;
 229                                 break;
 230                         }
 231                         tty->canon_column = tty->column = 0;
 232                         break;
 233                 case '\t':
 234                         goto break_out;
 235                 case '\b':
 236                         if (tty->column > 0)
 237                                 tty->column--;
 238                         break;
 239                 default:
 240                         if (O_OLCUC(tty))
 241                                 *cp = toupper(*cp);
 242                         if (!iscntrl(*cp))
 243                                 tty->column++;
 244                         break;
 245                 }
 246         }
 247 break_out:
 248         if (tty->driver.flush_chars)
 249                 tty->driver.flush_chars(tty);
 250         i = tty->driver.write(tty, 0, buf, i);
 251         return i;
 252 }
 253
 254
 255
 256 static inline void put_char(unsigned char c, struct tty_struct *tty)
 257 {
 258         tty->driver.put_char(tty, c);
 259 }
 260
 261 /* Must be called only when L_ECHO(tty) is true. */
 262
 263 static void echo_char(unsigned char c, struct tty_struct *tty)
 264 {
 265         if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
 266                 put_char('^', tty);
 267                 put_char(c ^ 0100, tty);
 268                 tty->column += 2;
 269         } else
 270                 opost(c, tty);
 271 }
 272
 273 static inline void finish_erasing(struct tty_struct *tty)
 274 {
 275         if (tty->erasing) {
 276                 put_char('/', tty);
 277                 tty->column += 2;
 278                 tty->erasing = 0;
 279         }
 280 }
 281
 282 static void eraser(unsigned char c, struct tty_struct *tty)
 283 {
 284         enum { ERASE, WERASE, KILL } kill_type;
 285         int head, seen_alnums;
 286
 287         if (tty->read_head == tty->canon_head) {
 288                 /* opost('\a', tty); */         /* what do you think? */
 289                 return;
 290         }
 291         if (c == ERASE_CHAR(tty))
 292                 kill_type = ERASE;
 293         else if (c == WERASE_CHAR(tty))
 294                 kill_type = WERASE;
 295         else {
 296                 if (!L_ECHO(tty)) {
 297                         tty->read_cnt -= ((tty->read_head - tty->canon_head) &
 298                                           (N_TTY_BUF_SIZE - 1));
 299                         tty->read_head = tty->canon_head;
 300                         return;
 301                 }
 302                 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
 303                         tty->read_cnt -= ((tty->read_head - tty->canon_head) &
 304                                           (N_TTY_BUF_SIZE - 1));
 305                         tty->read_head = tty->canon_head;
 306                         finish_erasing(tty);
 307                         echo_char(KILL_CHAR(tty), tty);
 308                         /* Add a newline if ECHOK is on and ECHOKE is off. */
 309                         if (L_ECHOK(tty))
 310                                 opost('\n', tty);
 311                         return;
 312                 }
 313                 kill_type = KILL;
 314         }
 315
 316         seen_alnums = 0;
 317         while (tty->read_head != tty->canon_head) {
 318                 head = (tty->read_head - 1) & (N_TTY_BUF_SIZE-1);
 319                 c = tty->read_buf[head];
 320                 if (kill_type == WERASE) {
 321                         /* Equivalent to BSD's ALTWERASE. */
 322                         if (isalnum(c) || c == '_')
 323                                 seen_alnums++;
 324                         else if (seen_alnums)
 325                                 break;
 326                 }
 327                 tty->read_head = head;
 328                 tty->read_cnt--;
 329                 if (L_ECHO(tty)) {
 330                         if (L_ECHOPRT(tty)) {
 331                                 if (!tty->erasing) {
 332                                         put_char('\\', tty);
 333                                         tty->column++;
 334                                         tty->erasing = 1;
 335                                 }
 336                                 echo_char(c, tty);
 337                         } else if (kill_type == ERASE && !L_ECHOE(tty)) {
 338                                 echo_char(ERASE_CHAR(tty), tty);
 339                         } else if (c == '\t') {
 340                                 unsigned int col = tty->canon_column;
 341                                 unsigned long tail = tty->canon_head;
 342
 343                                 /* Find the column of the last char. */
 344                                 while (tail != tty->read_head) {
 345                                         c = tty->read_buf[tail];
 346                                         if (c == '\t')
 347                                                 col = (col | 7) + 1;
 348                                         else if (iscntrl(c)) {
 349                                                 if (L_ECHOCTL(tty))
 350                                                         col += 2;
 351                                         } else
 352                                                 col++;
 353                                         tail = (tail+1) & (N_TTY_BUF_SIZE-1);
 354                                 }
 355
 356                                 /* should never happen */
 357                                 if (tty->column > 0x80000000)
 358                                         tty->column = 0;
 359
 360                                 /* Now backup to that column. */
 361                                 while (tty->column > col) {
 362                                         /* Can't use opost here. */
 363                                         put_char('\b', tty);
 364                                         if (tty->column > 0)
 365                                                 tty->column--;
 366                                 }
 367                         } else {
 368                                 if (iscntrl(c) && L_ECHOCTL(tty)) {
 369                                         put_char('\b', tty);
 370                                         put_char(' ', tty);
 371                                         put_char('\b', tty);
 372                                         if (tty->column > 0)
 373                                                 tty->column--;
 374                                 }
 375                                 if (!iscntrl(c) || L_ECHOCTL(tty)) {
 376                                         put_char('\b', tty);
 377                                         put_char(' ', tty);
 378                                         put_char('\b', tty);
 379                                         if (tty->column > 0)
 380                                                 tty->column--;
 381                                 }
 382                         }
 383                 }
 384                 if (kill_type == ERASE)
 385                         break;
 386         }
 387         if (tty->read_head == tty->canon_head)
 388                 finish_erasing(tty);
 389 }
 390
 391 static inline void isig(int sig, struct tty_struct *tty, int flush)
 392 {
 393         if (tty->pgrp > 0)
 394                 kill_pg(tty->pgrp, sig, 1);
 395         if (flush || !L_NOFLSH(tty)) {
 396                 n_tty_flush_buffer(tty);
 397                 if (tty->driver.flush_buffer)
 398                         tty->driver.flush_buffer(tty);
 399         }
 400 }
 401
 402 static inline void n_tty_receive_break(struct tty_struct *tty)
 403 {
 404         if (I_IGNBRK(tty))
 405                 return;
 406         if (I_BRKINT(tty)) {
 407                 isig(SIGINT, tty, 1);
 408                 return;
 409         }
 410         if (I_PARMRK(tty)) {
 411                 put_tty_queue('\377', tty);
 412                 put_tty_queue('\0', tty);
 413         }
 414         put_tty_queue('\0', tty);
 415         wake_up_interruptible(&tty->read_wait);
 416 }
 417
 418 static inline void n_tty_receive_overrun(struct tty_struct *tty)
 419 {
 420         char buf[64];
 421
 422         tty->num_overrun++;
 423         if (time_before(tty->overrun_time, jiffies - HZ)) {
 424                 printk("%s: %d input overrun(s)\n", tty_name(tty, buf),
 425                        tty->num_overrun);
 426                 tty->overrun_time = jiffies;
 427                 tty->num_overrun = 0;
 428         }
 429 }
 430
 431 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
 432                                               unsigned char c)
 433 {
 434         if (I_IGNPAR(tty)) {
 435                 return;
 436         }
 437         if (I_PARMRK(tty)) {
 438                 put_tty_queue('\377', tty);
 439                 put_tty_queue('\0', tty);
 440                 put_tty_queue(c, tty);
 441         } else  if (I_INPCK(tty))
 442                 put_tty_queue('\0', tty);
 443         else
 444                 put_tty_queue(c, tty);
 445         wake_up_interruptible(&tty->read_wait);
 446 }
 447
 448 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
 449 {
 450         if (tty->raw) {
 451                 put_tty_queue(c, tty);
 452                 return;
 453         }
 454
 455         if (tty->stopped && !tty->flow_stopped &&
 456             I_IXON(tty) && I_IXANY(tty)) {
 457                 start_tty(tty);
 458                 return;
 459         }
 460
 461         if (I_ISTRIP(tty))
 462                 c &= 0x7f;
 463         if (I_IUCLC(tty) && L_IEXTEN(tty))
 464                 c=tolower(c);
 465
 466         if (tty->closing) {
 467                 if (I_IXON(tty)) {
 468                         if (c == START_CHAR(tty))
 469                                 start_tty(tty);
 470                         else if (c == STOP_CHAR(tty))
 471                                 stop_tty(tty);
 472                 }
 473                 return;
 474         }
 475
 476         /*
 477          * If the previous character was LNEXT, or we know that this
 478          * character is not one of the characters that we'll have to
 479          * handle specially, do shortcut processing to speed things
 480          * up.
 481          */
 482         if (!test_bit(c, &tty->process_char_map) || tty->lnext) {
 483                 finish_erasing(tty);
 484                 tty->lnext = 0;
 485                 if (L_ECHO(tty)) {
 486                         if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
 487                                 put_char('\a', tty); /* beep if no space */
 488                                 return;
 489                         }
 490                         /* Record the column of first canon char. */
 491                         if (tty->canon_head == tty->read_head)
 492                                 tty->canon_column = tty->column;
 493                         echo_char(c, tty);
 494                 }
 495                 if (I_PARMRK(tty) && c == (unsigned char) '\377')
 496                         put_tty_queue(c, tty);
 497                 put_tty_queue(c, tty);
 498                 return;
 499         }
 500
 501         if (c == '\r') {
 502                 if (I_IGNCR(tty))
 503                         return;
 504                 if (I_ICRNL(tty))
 505                         c = '\n';
 506         } else if (c == '\n' && I_INLCR(tty))
 507                 c = '\r';
 508         if (I_IXON(tty)) {
 509                 if (c == START_CHAR(tty)) {
 510                         start_tty(tty);
 511                         return;
 512                 }
 513                 if (c == STOP_CHAR(tty)) {
 514                         stop_tty(tty);
 515                         return;
 516                 }
 517         }
 518         if (L_ISIG(tty)) {
 519                 int signal;
 520                 signal = SIGINT;
 521                 if (c == INTR_CHAR(tty))
 522                         goto send_signal;
 523                 signal = SIGQUIT;
 524                 if (c == QUIT_CHAR(tty))
 525                         goto send_signal;
 526                 signal = SIGTSTP;
 527                 if (c == SUSP_CHAR(tty)) {
 528 send_signal:
 529                         isig(signal, tty, 0);
 530                         return;
 531                 }
 532         }
 533         if (tty->icanon) {
 534                 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
 535                     (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
 536                         eraser(c, tty);
 537                         return;
 538                 }
 539                 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
 540                         tty->lnext = 1;
 541                         if (L_ECHO(tty)) {
 542                                 finish_erasing(tty);
 543                                 if (L_ECHOCTL(tty)) {
 544                                         put_char('^', tty);
 545                                         put_char('\b', tty);
 546                                 }
 547                         }
 548                         return;
 549                 }
 550                 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
 551                     L_IEXTEN(tty)) {
 552                         unsigned long tail = tty->canon_head;
 553
 554                         finish_erasing(tty);
 555                         echo_char(c, tty);
 556                         opost('\n', tty);
 557                         while (tail != tty->read_head) {
 558                                 echo_char(tty->read_buf[tail], tty);
 559                                 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
 560                         }
 561                         return;
 562                 }
 563                 if (c == '\n') {
 564                         if (L_ECHO(tty) || L_ECHONL(tty)) {
 565                                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
 566                                         put_char('\a', tty);
 567                                         return;
 568                                 }
 569                                 opost('\n', tty);
 570                         }
 571                         goto handle_newline;
 572                 }
 573                 if (c == EOF_CHAR(tty)) {
 574                         if (tty->canon_head != tty->read_head)
 575                                 set_bit(TTY_PUSH, &tty->flags);
 576                         c = __DISABLED_CHAR;
 577                         goto handle_newline;
 578                 }
 579                 if ((c == EOL_CHAR(tty)) ||
 580                     (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
 581                         /*
 582                          * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
 583                          */
 584                         if (L_ECHO(tty)) {
 585                                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
 586                                         put_char('\a', tty);
 587                                         return;
 588                                 }
 589                                 /* Record the column of first canon char. */
 590                                 if (tty->canon_head == tty->read_head)
 591                                         tty->canon_column = tty->column;
 592                                 echo_char(c, tty);
 593                         }
 594                         /*
 595                          * XXX does PARMRK doubling happen for
 596                          * EOL_CHAR and EOL2_CHAR?
 597                          */
 598                         if (I_PARMRK(tty) && c == (unsigned char) '\377')
 599                                 put_tty_queue(c, tty);
 600
 601                 handle_newline:
 602                         set_bit(tty->read_head, &tty->read_flags);
 603                         put_tty_queue(c, tty);
 604                         tty->canon_head = tty->read_head;
 605                         tty->canon_data++;
 606                         if (tty->fasync)
 607                                 kill_fasync(tty->fasync, SIGIO);
 608                         if (waitqueue_active(&tty->read_wait))
 609                                 wake_up_interruptible(&tty->read_wait);
 610                         return;
 611                 }
 612         }
 613
 614         finish_erasing(tty);
 615         if (L_ECHO(tty)) {
 616                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
 617                         put_char('\a', tty); /* beep if no space */
 618                         return;
 619                 }
 620                 if (c == '\n')
 621                         opost('\n', tty);
 622                 else {
 623                         /* Record the column of first canon char. */
 624                         if (tty->canon_head == tty->read_head)
 625                                 tty->canon_column = tty->column;
 626                         echo_char(c, tty);
 627                 }
 628         }
 629
 630         if (I_PARMRK(tty) && c == (unsigned char) '\377')
 631                 put_tty_queue(c, tty);
 632
 633         put_tty_queue(c, tty);
 634 }
 635
 636 static int n_tty_receive_room(struct tty_struct *tty)
 637 {
 638         int     left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
 639
 640         /*
 641          * If we are doing input canonicalization, and there are no
 642          * pending newlines, let characters through without limit, so
 643          * that erase characters will be handled.  Other excess
 644          * characters will be beeped.
 645          */
 646         if (tty->icanon && !tty->canon_data)
 647                 return N_TTY_BUF_SIZE;
 648
 649         if (left > 0)
 650                 return left;
 651         return 0;
 652 }
 653
 654 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 655                               char *fp, int count)
 656 {
 657         const unsigned char *p;
 658         char *f, flags = TTY_NORMAL;
 659         int     i;
 660         char    buf[64];
 661
 662         if (!tty->read_buf)
 663                 return;
 664
 665         if (tty->real_raw) {
 666                 i = MIN(count, MIN(N_TTY_BUF_SIZE - tty->read_cnt,
 667                                    N_TTY_BUF_SIZE - tty->read_head));
 668                 memcpy(tty->read_buf + tty->read_head, cp, i);
 669                 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
 670                 tty->read_cnt += i;
 671                 cp += i;
 672                 count -= i;
 673
 674                 i = MIN(count, MIN(N_TTY_BUF_SIZE - tty->read_cnt,
 675                                N_TTY_BUF_SIZE - tty->read_head));
 676                 memcpy(tty->read_buf + tty->read_head, cp, i);
 677                 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
 678                 tty->read_cnt += i;
 679         } else {
 680                 for (i=count, p = cp, f = fp; i; i--, p++) {
 681                         if (f)
 682                                 flags = *f++;
 683                         switch (flags) {
 684                         case TTY_NORMAL:
 685                                 n_tty_receive_char(tty, *p);
 686                                 break;
 687                         case TTY_BREAK:
 688                                 n_tty_receive_break(tty);
 689                                 break;
 690                         case TTY_PARITY:
 691                         case TTY_FRAME:
 692                                 n_tty_receive_parity_error(tty, *p);
 693                                 break;
 694                         case TTY_OVERRUN:
 695                                 n_tty_receive_overrun(tty);
 696                                 break;
 697                         default:
 698                                 printk("%s: unknown flag %d\n",
 699                                        tty_name(tty, buf), flags);
 700                                 break;
 701                         }
 702                 }
 703                 if (tty->driver.flush_chars)
 704                         tty->driver.flush_chars(tty);
 705         }
 706
 707         if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
 708                 if (tty->fasync)
 709                         kill_fasync(tty->fasync, SIGIO);
 710                 if (waitqueue_active(&tty->read_wait))
 711                         wake_up_interruptible(&tty->read_wait);
 712         }
 713
 714         /*
 715          * Check the remaining room for the input canonicalization
 716          * mode.  We don't want to throttle the driver if we're in
 717          * canonical mode and don't have a newline yet!
 718          */
 719         if (n_tty_receive_room(tty) < TTY_THRESHOLD_THROTTLE) {
 720                 /* check TTY_THROTTLED first so it indicates our state */
 721                 if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
 722                     tty->driver.throttle)
 723                         tty->driver.throttle(tty);
 724         }
 725 }
 726
 727 int is_ignored(int sig)
 728 {
 729         return (sigismember(&current->blocked, sig) ||
 730                 current->sig->action[sig-1].sa.sa_handler == SIG_IGN);
 731 }
 732
 733 static void n_tty_set_termios(struct tty_struct *tty, struct termios * old)
 734 {
 735         if (!tty)
 736                 return;
 737
 738         tty->icanon = (L_ICANON(tty) != 0);
 739         if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
 740                 tty->raw = 1;
 741                 tty->real_raw = 1;
 742                 return;
 743         }
 744         if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
 745             I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
 746             I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
 747             I_PARMRK(tty)) {
 748                 cli();
 749                 memset(tty->process_char_map, 0, 256/8);
 750
 751                 if (I_IGNCR(tty) || I_ICRNL(tty))
 752                         set_bit('\r', &tty->process_char_map);
 753                 if (I_INLCR(tty))
 754                         set_bit('\n', &tty->process_char_map);
 755
 756                 if (L_ICANON(tty)) {
 757                         set_bit(ERASE_CHAR(tty), &tty->process_char_map);
 758                         set_bit(KILL_CHAR(tty), &tty->process_char_map);
 759                         set_bit(EOF_CHAR(tty), &tty->process_char_map);
 760                         set_bit('\n', &tty->process_char_map);
 761                         set_bit(EOL_CHAR(tty), &tty->process_char_map);
 762                         if (L_IEXTEN(tty)) {
 763                                 set_bit(WERASE_CHAR(tty),
 764                                         &tty->process_char_map);
 765                                 set_bit(LNEXT_CHAR(tty),
 766                                         &tty->process_char_map);
 767                                 set_bit(EOL2_CHAR(tty),
 768                                         &tty->process_char_map);
 769                                 if (L_ECHO(tty))
 770                                         set_bit(REPRINT_CHAR(tty),
 771                                                 &tty->process_char_map);
 772                         }
 773                 }
 774                 if (I_IXON(tty)) {
 775                         set_bit(START_CHAR(tty), &tty->process_char_map);
 776                         set_bit(STOP_CHAR(tty), &tty->process_char_map);
 777                 }
 778                 if (L_ISIG(tty)) {
 779                         set_bit(INTR_CHAR(tty), &tty->process_char_map);
 780                         set_bit(QUIT_CHAR(tty), &tty->process_char_map);
 781                         set_bit(SUSP_CHAR(tty), &tty->process_char_map);
 782                 }
 783                 clear_bit(__DISABLED_CHAR, &tty->process_char_map);
 784                 sti();
 785                 tty->raw = 0;
 786                 tty->real_raw = 0;
 787         } else {
 788                 tty->raw = 1;
 789                 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
 790                     (I_IGNPAR(tty) || !I_INPCK(tty)) &&
 791                     (tty->driver.flags & TTY_DRIVER_REAL_RAW))
 792                         tty->real_raw = 1;
 793                 else
 794                         tty->real_raw = 0;
 795         }
 796 }
 797
 798 static void n_tty_close(struct tty_struct *tty)
 799 {
 800         n_tty_flush_buffer(tty);
 801         if (tty->read_buf) {
 802                 free_page((unsigned long) tty->read_buf);
 803                 tty->read_buf = 0;
 804         }
 805 }
 806
 807 static int n_tty_open(struct tty_struct *tty)
 808 {
 809         if (!tty)
 810                 return -EINVAL;
 811
 812         if (!tty->read_buf) {
 813                 tty->read_buf = (unsigned char *)
 814                         get_free_page(in_interrupt() ? GFP_ATOMIC : GFP_KERNEL);
 815                 if (!tty->read_buf)
 816                         return -ENOMEM;
 817         }
 818         memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
 819         reset_buffer_flags(tty);
 820         tty->column = 0;
 821         n_tty_set_termios(tty, 0);
 822         tty->minimum_to_wake = 1;
 823         tty->closing = 0;
 824         return 0;
 825 }
 826
 827 static inline int input_available_p(struct tty_struct *tty, int amt)
 828 {
 829         if (tty->icanon) {
 830                 if (tty->canon_data)
 831                         return 1;
 832         } else if (tty->read_cnt >= (amt ? amt : 1))
 833                 return 1;
 834
 835         return 0;
 836 }
 837
 838 /*
 839  * Helper function to speed up read_chan.  It is only called when
 840  * ICANON is off; it copies characters straight from the tty queue to
 841  * user space directly.  It can be profitably called twice; once to
 842  * drain the space from the tail pointer to the (physical) end of the
 843  * buffer, and once to drain the space from the (physical) beginning of
 844  * the buffer to head pointer.
 845  */
 846 static inline int copy_from_read_buf(struct tty_struct *tty,
 847                                       unsigned char **b,
 848                                       size_t *nr)
 849
 850 {
 851         int retval;
 852         ssize_t n;
 853
 854         retval = 0;
 855         n = MIN(*nr, MIN(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail));
 856         if (n) {
 857                 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
 858                 n -= retval;
 859                 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
 860                 tty->read_cnt -= n;
 861                 *b += n;
 862                 *nr -= n;
 863         }
 864         return retval;
 865 }
 866
 867 static ssize_t read_chan(struct tty_struct *tty, struct file *file,
 868                          unsigned char *buf, size_t nr)
 869 {
 870         unsigned char *b = buf;
 871         DECLARE_WAITQUEUE(wait, current);
 872         int c;
 873         int minimum, time;
 874         ssize_t retval = 0;
 875         ssize_t size;
 876         long timeout;
 877
 878 do_it_again:
 879
 880         if (!tty->read_buf) {
 881                 printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
 882                 return -EIO;
 883         }
 884
 885         /* Job control check -- must be done at start and after
 886            every sleep (POSIX.1 7.1.1.4). */
 887         /* NOTE: not yet done after every sleep pending a thorough
 888            check of the logic of this change. -- jlc */
 889         /* don't stop on /dev/console */
 890         if (file->f_dentry->d_inode->i_rdev != CONSOLE_DEV &&
 891             file->f_dentry->d_inode->i_rdev != SYSCONS_DEV &&
 892             current->tty == tty) {
 893                 if (tty->pgrp <= 0)
 894                         printk("read_chan: tty->pgrp <= 0!\n");
 895                 else if (current->pgrp != tty->pgrp) {
 896                         if (is_ignored(SIGTTIN) ||
 897                             is_orphaned_pgrp(current->pgrp))
 898                                 return -EIO;
 899                         kill_pg(current->pgrp, SIGTTIN, 1);
 900                         return -ERESTARTSYS;
 901                 }
 902         }
 903
 904         minimum = time = 0;
 905         timeout = MAX_SCHEDULE_TIMEOUT;
 906         if (!tty->icanon) {
 907                 time = (HZ / 10) * TIME_CHAR(tty);
 908                 minimum = MIN_CHAR(tty);
 909                 if (minimum) {
 910                         if (time)
 911                                 tty->minimum_to_wake = 1;
 912                         else if (!waitqueue_active(&tty->read_wait) ||
 913                                  (tty->minimum_to_wake > minimum))
 914                                 tty->minimum_to_wake = minimum;
 915                 } else {
 916                         timeout = 0;
 917                         if (time) {
 918                                 timeout = time;
 919                                 time = 0;
 920                         }
 921                         tty->minimum_to_wake = minimum = 1;
 922                 }
 923         }
 924
 925         if (file->f_flags & O_NONBLOCK) {
 926                 if (down_trylock(&tty->atomic_read))
 927                         return -EAGAIN;
 928         }
 929         else {
 930                 if (down_interruptible(&tty->atomic_read))
 931                         return -ERESTARTSYS;
 932         }
 933
 934         add_wait_queue(&tty->read_wait, &wait);
 935         set_bit(TTY_DONT_FLIP, &tty->flags);
 936         while (nr) {
 937                 /* First test for status change. */
 938                 if (tty->packet && tty->link->ctrl_status) {
 939                         unsigned char cs;
 940                         if (b != buf)
 941                                 break;
 942                         cs = tty->link->ctrl_status;
 943                         tty->link->ctrl_status = 0;
 944                         put_user(cs, b++);
 945                         nr--;
 946                         break;
 947                 }
 948                 /* This statement must be first before checking for input
 949                    so that any interrupt will set the state back to
 950                    TASK_RUNNING. */
 951                 current->state = TASK_INTERRUPTIBLE;
 952
 953                 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
 954                     ((minimum - (b - buf)) >= 1))
 955                         tty->minimum_to_wake = (minimum - (b - buf));
 956
 957                 if (!input_available_p(tty, 0)) {
 958                         if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
 959                                 retval = -EIO;
 960                                 break;
 961                         }
 962                         if (tty_hung_up_p(file))
 963                                 break;
 964                         if (!timeout)
 965                                 break;
 966                         if (file->f_flags & O_NONBLOCK) {
 967                                 retval = -EAGAIN;
 968                                 break;
 969                         }
 970                         if (signal_pending(current)) {
 971                                 retval = -ERESTARTSYS;
 972                                 break;
 973                         }
 974                         clear_bit(TTY_DONT_FLIP, &tty->flags);
 975                         timeout = schedule_timeout(timeout);
 976                         set_bit(TTY_DONT_FLIP, &tty->flags);
 977                         continue;
 978                 }
 979                 current->state = TASK_RUNNING;
 980
 981                 /* Deal with packet mode. */
 982                 if (tty->packet && b == buf) {
 983                         put_user(TIOCPKT_DATA, b++);
 984                         nr--;
 985                 }
 986
 987                 if (tty->icanon) {
 988                         /* N.B. avoid overrun if nr == 0 */
 989                         while (nr && tty->read_cnt) {
 990                                 int eol;
 991
 992                                 eol = test_and_clear_bit(tty->read_tail,
 993                                                 &tty->read_flags);
 994                                 c = tty->read_buf[tty->read_tail];
 995                                 tty->read_tail = ((tty->read_tail+1) &
 996                                                   (N_TTY_BUF_SIZE-1));
 997                                 tty->read_cnt--;
 998
 999                                 if (!eol || (c != __DISABLED_CHAR)) {
1000                                         put_user(c, b++);
1001                                         nr--;
1002                                 }
1003                                 if (eol) {
1004                                         /* this test should be redundant:
1005                                          * we shouldn't be reading data if
1006                                          * canon_data is 0
1007                                          */
1008                                         if (--tty->canon_data < 0)
1009                                                 tty->canon_data = 0;
1010                                         break;
1011                                 }
1012                         }
1013                 } else {
1014                         int uncopied;
1015                         uncopied = copy_from_read_buf(tty, &b, &nr);
1016                         uncopied += copy_from_read_buf(tty, &b, &nr);
1017                         if (uncopied) {
1018                                 retval = -EFAULT;
1019                                 break;
1020                         }
1021                 }
1022
1023                 /* If there is enough space in the read buffer now, let the
1024                  * low-level driver know. We use n_tty_chars_in_buffer() to
1025                  * check the buffer, as it now knows about canonical mode.
1026                  * Otherwise, if the driver is throttled and the line is
1027                  * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1028                  * we won't get any more characters.
1029                  */
1030                 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE)
1031                         check_unthrottle(tty);
1032
1033                 if (b - buf >= minimum)
1034                         break;
1035                 if (time)
1036                         timeout = time;
1037         }
1038         clear_bit(TTY_DONT_FLIP, &tty->flags);
1039         up(&tty->atomic_read);
1040         remove_wait_queue(&tty->read_wait, &wait);
1041
1042         if (!waitqueue_active(&tty->read_wait))
1043                 tty->minimum_to_wake = minimum;
1044
1045         current->state = TASK_RUNNING;
1046         size = b - buf;
1047         if (size) {
1048                 retval = size;
1049                 if (nr)
1050                         clear_bit(TTY_PUSH, &tty->flags);
1051         } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1052                  goto do_it_again;
1053
1054         return retval;
1055 }
1056
1057 static ssize_t write_chan(struct tty_struct * tty, struct file * file,
1058                           const unsigned char * buf, size_t nr)
1059 {
1060         const unsigned char *b = buf;
1061         DECLARE_WAITQUEUE(wait, current);
1062         int c;
1063         ssize_t retval = 0;
1064
1065         /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1066         if (L_TOSTOP(tty) &&
1067             file->f_dentry->d_inode->i_rdev != CONSOLE_DEV &&
1068             file->f_dentry->d_inode->i_rdev != SYSCONS_DEV) {
1069                 retval = tty_check_change(tty);
1070                 if (retval)
1071                         return retval;
1072         }
1073
1074         add_wait_queue(&tty->write_wait, &wait);
1075         while (1) {
1076                 current->state = TASK_INTERRUPTIBLE;
1077                 if (signal_pending(current)) {
1078                         retval = -ERESTARTSYS;
1079                         break;
1080                 }
1081                 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1082                         retval = -EIO;
1083                         break;
1084                 }
1085                 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1086                         while (nr > 0) {
1087                                 ssize_t num = opost_block(tty, b, nr);
1088                                 if (num < 0) {
1089                                         retval = num;
1090                                         goto break_out;
1091                                 }
1092                                 b += num;
1093                                 nr -= num;
1094                                 if (nr == 0)
1095                                         break;
1096                                 get_user(c, b);
1097                                 if (opost(c, tty) < 0)
1098                                         break;
1099                                 b++; nr--;
1100                         }
1101                         if (tty->driver.flush_chars)
1102                                 tty->driver.flush_chars(tty);
1103                 } else {
1104                         c = tty->driver.write(tty, 1, b, nr);
1105                         if (c < 0) {
1106                                 retval = c;
1107                                 goto break_out;
1108                         }
1109                         b += c;
1110                         nr -= c;
1111                 }
1112                 if (!nr)
1113                         break;
1114                 if (file->f_flags & O_NONBLOCK) {
1115                         retval = -EAGAIN;
1116                         break;
1117                 }
1118                 schedule();
1119         }
1120 break_out:
1121         current->state = TASK_RUNNING;
1122         remove_wait_queue(&tty->write_wait, &wait);
1123         return (b - buf) ? b - buf : retval;
1124 }
1125
1126 static unsigned int normal_poll(struct tty_struct * tty, struct file * file, poll_table *wait)
1127 {
1128         unsigned int mask = 0;
1129
1130         poll_wait(file, &tty->read_wait, wait);
1131         poll_wait(file, &tty->write_wait, wait);
1132         if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
1133                 mask |= POLLIN | POLLRDNORM;
1134         if (tty->packet && tty->link->ctrl_status)
1135                 mask |= POLLPRI | POLLIN | POLLRDNORM;
1136         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
1137                 mask |= POLLHUP;
1138         if (tty_hung_up_p(file))
1139                 mask |= POLLHUP;
1140         if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
1141                 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
1142                         tty->minimum_to_wake = MIN_CHAR(tty);
1143                 else
1144                         tty->minimum_to_wake = 1;
1145         }
1146         if (tty->driver.chars_in_buffer(tty) < WAKEUP_CHARS)
1147                 mask |= POLLOUT | POLLWRNORM;
1148         return mask;
1149 }
1150
1151 struct tty_ldisc tty_ldisc_N_TTY = {
1152         TTY_LDISC_MAGIC,        /* magic */
1153         "n_tty",                /* name */
1154         0,                      /* num */
1155         0,                      /* flags */
1156         n_tty_open,             /* open */
1157         n_tty_close,            /* close */
1158         n_tty_flush_buffer,     /* flush_buffer */
1159         n_tty_chars_in_buffer,  /* chars_in_buffer */
1160         read_chan,              /* read */
1161         write_chan,             /* write */
1162         n_tty_ioctl,            /* ioctl */
1163         n_tty_set_termios,      /* set_termios */
1164         normal_poll,            /* poll */
1165         n_tty_receive_buf,      /* receive_buf */
1166         n_tty_receive_room,     /* receive_room */
1167         0                       /* write_wakeup */
1168 };
1169