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