kernel/chr_drv/tty

/* */
This source file includes following definitions.
tty_register_ldisc
put_tty_queue
get_tty_queue
tty_read_raw_data
tty_write_flush
tty_read_flush
hung_up_tty_read
hung_up_tty_write
hung_up_tty_select
hung_up_tty_ioctl
tty_lseek
do_tty_hangup
tty_hangup
tty_vhangup
tty_unhangup
tty_hung_up_p
vt_waitactive
complete_change_console
change_console
wait_for_keypress
copy_to_cooked
is_ignored
wait_for_canon_input
read_chan
__wait_for_canon_input
available_canon_input
write_chan
tty_read
tty_write
init_dev
release_dev
tty_open
tty_release
tty_select
do_SAK
tty_write_data
tty_bh_routine
initialize_tty_struct
initialize_termios
tty_init
   1 /*
   2  *  linux/kernel/tty_io.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
   9  * or rs-channels. It also implements echoing, cooked mode etc.
  10  *
  11  * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
  12  *
  13  * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
  14  * tty_struct and tty_queue structures.  Previously there was a array
  15  * of 256 tty_struct's which was statically allocated, and the
  16  * tty_queue structures were allocated at boot time.  Both are now
  17  * dynamically allocated only when the tty is open.
  18  *
  19  * Also restructured routines so that there is more of a separation
  20  * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
  21  * the low-level tty routines (serial.c, pty.c, console.c).  This
  22  * makes for cleaner and more compact code.  -TYT, 9/17/92 
  23  *
  24  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
  25  * which can be dynamically activated and de-activated by the line
  26  * discipline handling modules (like SLIP).
  27  *
  28  * NOTE: pay no attention to the line discpline code (yet); its
  29  * interface is still subject to change in this version...
  30  * -- TYT, 1/31/92
  31  *
  32  * Added functionality to the OPOST tty handling.  No delays, but all
  33  * other bits should be there.
  34  *      -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
  35  */
  36 
  37 #include <linux/types.h>
  38 #include <linux/errno.h>
  39 #include <linux/signal.h>
  40 #include <linux/fcntl.h>
  41 #include <linux/sched.h>
  42 #include <linux/tty.h>
  43 #include <linux/timer.h>
  44 #include <linux/ctype.h>
  45 #include <linux/kd.h>
  46 #include <linux/mm.h>
  47 #include <linux/string.h>
  48 #include <linux/keyboard.h>
  49 
  50 #include <asm/segment.h>
  51 #include <asm/system.h>
  52 #include <asm/bitops.h>
  53 
  54 #include "vt_kern.h"
  55 
  56 #define MAX_TTYS 256
  57 
  58 struct tty_struct *tty_table[MAX_TTYS];
  59 struct termios *tty_termios[MAX_TTYS];  /* We need to keep the termios state */
  60                                         /* around, even when a tty is closed */
  61 struct termios *termios_locked[MAX_TTYS]; /* Bitfield of locked termios flags*/
  62 struct tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
  63 int tty_check_write[MAX_TTYS/32];       /* bitfield for the bh handler */
  64 
  65 /*
  66  * fg_console is the current virtual console,
  67  * redirect is the pseudo-tty that console output
  68  * is redirected to if asked by TIOCCONS.
  69  */
  70 int fg_console = 0;
  71 struct tty_struct * redirect = NULL;
  72 struct wait_queue * keypress_wait = NULL;
  73 
  74 static void initialize_tty_struct(int line, struct tty_struct *tty);
  75 static void initialize_termios(int line, struct termios *tp);
  76 
  77 static int tty_read(struct inode *, struct file *, char *, int);
  78 static int tty_write(struct inode *, struct file *, char *, int);
  79 static int tty_select(struct inode *, struct file *, int, select_table *);
  80 static int tty_open(struct inode *, struct file *);
  81 static void tty_release(struct inode *, struct file *);
  82 
  83 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
     /*  */
  84 {
  85         if (disc < N_TTY || disc >= NR_LDISCS)
  86                 return -EINVAL;
  87         
  88         if (new_ldisc) {
  89                 ldiscs[disc] = *new_ldisc;
  90                 ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
  91         } else
  92                 memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
  93         
  94         return 0;
  95 }
  96 
  97 void put_tty_queue(char c, struct tty_queue * queue)
     /*  */
  98 {
  99         int head;
 100         unsigned long flags;
 101 
 102         save_flags(flags);
 103         cli();
 104         head = (queue->head + 1) & (TTY_BUF_SIZE-1);
 105         if (head != queue->tail) {
 106                 queue->buf[queue->head] = c;
 107                 queue->head = head;
 108         }
 109         restore_flags(flags);
 110 }
 111 
 112 int get_tty_queue(struct tty_queue * queue)
     /*  */
 113 {
 114         int result = -1;
 115         unsigned long flags;
 116 
 117         save_flags(flags);
 118         cli();
 119         if (queue->tail != queue->head) {
 120                 result = 0xff & queue->buf[queue->tail];
 121                 queue->tail = (queue->tail + 1) & (TTY_BUF_SIZE-1);
 122         }
 123         restore_flags(flags);
 124         return result;
 125 }
 126 
 127 /*
 128  * This routine copies out a maximum of buflen characters from the
 129  * read_q; it is a convenience for line disciplines so they can grab a
 130  * large block of data without calling get_tty_char directly.  It
 131  * returns the number of characters actually read. Return terminates
 132  * if an error character is read from the queue and the return value
 133  * is negated.
 134  */
 135 int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp, int buflen)
     /*  */
 136 {
 137         int     result = 0;
 138         unsigned char   *p = bufp;
 139         unsigned long flags;
 140         int head, tail;
 141         int ok = 1;
 142 
 143         save_flags(flags);
 144         cli();
 145         tail = tty->read_q.tail;
 146         head = tty->read_q.head;
 147         while ((result < buflen) && (tail!=head) && ok) {
 148                 ok = !clear_bit (tail, &tty->readq_flags);
 149                 *p++ =  tty->read_q.buf[tail++];
 150                 tail &= TTY_BUF_SIZE-1;
 151                 result++;
 152         }
 153         tty->read_q.tail = tail;
 154         restore_flags(flags);
 155         return (ok) ? result : -result;
 156 }
 157 
 158 
 159 void tty_write_flush(struct tty_struct * tty)
     /*  */
 160 {
 161         if (!tty->write || EMPTY(&tty->write_q))
 162                 return;
 163         if (set_bit(TTY_WRITE_BUSY,&tty->flags))
 164                 return;
 165         tty->write(tty);
 166         if (!clear_bit(TTY_WRITE_BUSY,&tty->flags))
 167                 printk("tty_write_flush: bit already cleared\n");
 168 }
 169 
 170 void tty_read_flush(struct tty_struct * tty)
     /*  */
 171 {
 172         if (!tty || EMPTY(&tty->read_q))
 173                 return;
 174         if (set_bit(TTY_READ_BUSY, &tty->flags))
 175                 return;
 176         ldiscs[tty->disc].handler(tty);
 177         if (!clear_bit(TTY_READ_BUSY, &tty->flags))
 178                 printk("tty_read_flush: bit already cleared\n");
 179 }
 180 
 181 static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 182 {
 183         return 0;
 184 }
 185 
 186 static int hung_up_tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 187 {
 188         return -EIO;
 189 }
 190 
 191 static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
 192 {
 193         return 1;
 194 }
 195 
 196 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
     /*  */
 197                              unsigned int cmd, unsigned long arg)
 198 {
 199         return -EIO;
 200 }
 201 
 202 static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 203 {
 204         return -ESPIPE;
 205 }
 206 
 207 static struct file_operations tty_fops = {
 208         tty_lseek,
 209         tty_read,
 210         tty_write,
 211         NULL,           /* tty_readdir */
 212         tty_select,
 213         tty_ioctl,
 214         NULL,           /* tty_mmap */
 215         tty_open,
 216         tty_release
 217 };
 218 
 219 static struct file_operations hung_up_tty_fops = {
 220         tty_lseek,
 221         hung_up_tty_read,
 222         hung_up_tty_write,
 223         NULL,           /* hung_up_tty_readdir */
 224         hung_up_tty_select,
 225         tty_ioctl,
 226         NULL,           /* hung_up_tty_mmap */
 227         tty_open,
 228         tty_release
 229 };
 230 
 231 static struct file_operations vhung_up_tty_fops = {
 232         tty_lseek,
 233         hung_up_tty_read,
 234         hung_up_tty_write,
 235         NULL,           /* hung_up_tty_readdir */
 236         hung_up_tty_select,
 237         hung_up_tty_ioctl,
 238         NULL,           /* hung_up_tty_mmap */
 239         tty_open,
 240         tty_release
 241 };
 242 
 243 void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
     /*  */
 244 {
 245         int i;
 246         struct file * filp;
 247         struct task_struct **p;
 248         int dev;
 249 
 250         if (!tty)
 251                 return;
 252         dev = 0x0400 + tty->line;
 253         for (filp = first_file, i=0; i<nr_files; i++, filp = filp->f_next) {
 254                 if (!filp->f_count)
 255                         continue;
 256                 if (filp->f_rdev != dev)
 257                         continue;
 258                 if (filp->f_inode && filp->f_inode->i_rdev == 0x0400)
 259                         continue;
 260                 if (filp->f_op != &tty_fops)
 261                         continue;
 262                 filp->f_op = fops;
 263         }
 264         wake_up_interruptible(&tty->secondary.proc_list);
 265         wake_up_interruptible(&tty->read_q.proc_list);
 266         wake_up_interruptible(&tty->write_q.proc_list);
 267         if (tty->session > 0)
 268                 kill_sl(tty->session,SIGHUP,1);
 269         tty->session = 0;
 270         tty->pgrp = -1;
 271         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
 272                 if ((*p) && (*p)->tty == tty->line)
 273                         (*p)->tty = -1;
 274         }
 275 }
 276 
 277 void tty_hangup(struct tty_struct * tty)
     /*  */
 278 {
 279         do_tty_hangup(tty, &hung_up_tty_fops);
 280 }
 281 
 282 void tty_vhangup(struct tty_struct * tty)
     /*  */
 283 {
 284         do_tty_hangup(tty, &vhung_up_tty_fops);
 285 }
 286 
 287 void tty_unhangup(struct file *filp)
     /*  */
 288 {
 289         filp->f_op = &tty_fops;
 290 }
 291 
 292 int tty_hung_up_p(struct file * filp)
     /*  */
 293 {
 294         return ((filp->f_op == &hung_up_tty_fops) ||
 295                 (filp->f_op == &vhung_up_tty_fops));
 296 }
 297 
 298 /*
 299  * Sometimes we want to wait until a particular VT has been activated. We
 300  * do it in a very simple manner. Everybody waits on a single queue and
 301  * get woken up at once. Those that are satisfied go on with their business,
 302  * while those not ready go back to sleep. Seems overkill to add a wait
 303  * to each vt just for this - usually this does nothing!
 304  */
 305 static struct wait_queue *vt_activate_queue = NULL;
 306 
 307 /*
 308  * Sleeps until a vt is activated, or the task is interrupted. Returns
 309  * 0 if activation, -1 if interrupted.
 310  */
 311 int vt_waitactive(void)
     /*  */
 312 {
 313         interruptible_sleep_on(&vt_activate_queue);
 314         return (current->signal & ~current->blocked) ? -1 : 0;
 315 }
 316 
 317 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 318 
 319 extern int kill_proc(int pid, int sig, int priv);
 320 
 321 /*
 322  * Performs the back end of a vt switch
 323  */
 324 void complete_change_console(unsigned int new_console)
     /*  */
 325 {
 326         unsigned char old_vc_mode;
 327 
 328         if (new_console == fg_console || new_console >= NR_CONSOLES)
 329                 return;
 330 
 331         /*
 332          * If we're switching, we could be going from KD_GRAPHICS to
 333          * KD_TEXT mode or vice versa, which means we need to blank or
 334          * unblank the screen later.
 335          */
 336         old_vc_mode = vt_cons[fg_console].vc_mode;
 337         update_screen(new_console);
 338 
 339         /*
 340          * If this new console is under process control, send it a signal
 341          * telling it that it has acquired. Also check if it has died and
 342          * clean up (similar to logic employed in change_console())
 343          */
 344         if (vt_cons[new_console].vt_mode.mode == VT_PROCESS)
 345         {
 346                 /*
 347                  * Send the signal as privileged - kill_proc() will
 348                  * tell us if the process has gone or something else
 349                  * is awry
 350                  */
 351                 if (kill_proc(vt_cons[new_console].vt_pid,
 352                               vt_cons[new_console].vt_mode.acqsig,
 353                               1) != 0)
 354                 {
 355                 /*
 356                  * The controlling process has died, so we revert back to
 357                  * normal operation. In this case, we'll also change back
 358                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 359                  * but it saves the agony when the X server dies and the screen
 360                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 361                  * this outside of VT_PROCESS but there is no single process
 362                  * to account for and tracking tty count may be undesirable.
 363                  */
 364                         vt_cons[new_console].vc_mode = KD_TEXT;
 365                         clr_vc_kbd_flag(kbd_table + new_console, VC_RAW);
 366                         vt_cons[new_console].vt_mode.mode = VT_AUTO;
 367                         vt_cons[new_console].vt_mode.waitv = 0;
 368                         vt_cons[new_console].vt_mode.relsig = 0;
 369                         vt_cons[new_console].vt_mode.acqsig = 0;
 370                         vt_cons[new_console].vt_mode.frsig = 0;
 371                         vt_cons[new_console].vt_pid = -1;
 372                         vt_cons[new_console].vt_newvt = -1;
 373                 }
 374         }
 375 
 376         /*
 377          * We do this here because the controlling process above may have
 378          * gone, and so there is now a new vc_mode
 379          */
 380         if (old_vc_mode != vt_cons[new_console].vc_mode)
 381         {
 382                 if (vt_cons[new_console].vc_mode == KD_TEXT)
 383                         unblank_screen();
 384                 else {
 385                         timer_active &= ~(1<<BLANK_TIMER);
 386                         blank_screen();
 387                 }
 388         }
 389 
 390         /*
 391          * Wake anyone waiting for their VT to activate
 392          */
 393         vt_wake_waitactive();
 394         return;
 395 }
 396 
 397 /*
 398  * Performs the front-end of a vt switch
 399  */
 400 void change_console(unsigned int new_console)
     /*  */
 401 {
 402         if (new_console == fg_console || new_console >= NR_CONSOLES)
 403                 return;
 404 
 405         /*
 406          * If this vt is in process mode, then we need to handshake with
 407          * that process before switching. Essentially, we store where that
 408          * vt wants to switch to and wait for it to tell us when it's done
 409          * (via VT_RELDISP ioctl).
 410          *
 411          * We also check to see if the controlling process still exists.
 412          * If it doesn't, we reset this vt to auto mode and continue.
 413          * This is a cheap way to track process control. The worst thing
 414          * that can happen is: we send a signal to a process, it dies, and
 415          * the switch gets "lost" waiting for a response; hopefully, the
 416          * user will try again, we'll detect the process is gone (unless
 417          * the user waits just the right amount of time :-) and revert the
 418          * vt to auto control.
 419          */
 420         if (vt_cons[fg_console].vt_mode.mode == VT_PROCESS)
 421         {
 422                 /*
 423                  * Send the signal as privileged - kill_proc() will
 424                  * tell us if the process has gone or something else
 425                  * is awry
 426                  */
 427                 if (kill_proc(vt_cons[fg_console].vt_pid,
 428                               vt_cons[fg_console].vt_mode.relsig,
 429                               1) == 0)
 430                 {
 431                         /*
 432                          * It worked. Mark the vt to switch to and
 433                          * return. The process needs to send us a
 434                          * VT_RELDISP ioctl to complete the switch.
 435                          */
 436                         vt_cons[fg_console].vt_newvt = new_console;
 437                         return;
 438                 }
 439 
 440                 /*
 441                  * The controlling process has died, so we revert back to
 442                  * normal operation. In this case, we'll also change back
 443                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 444                  * but it saves the agony when the X server dies and the screen
 445                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 446                  * this outside of VT_PROCESS but there is no single process
 447                  * to account for and tracking tty count may be undesirable.
 448                  */
 449                 vt_cons[fg_console].vc_mode = KD_TEXT;
 450                 clr_vc_kbd_flag(kbd_table + fg_console, VC_RAW);
 451                 vt_cons[fg_console].vt_mode.mode = VT_AUTO;
 452                 vt_cons[fg_console].vt_mode.waitv = 0;
 453                 vt_cons[fg_console].vt_mode.relsig = 0;
 454                 vt_cons[fg_console].vt_mode.acqsig = 0;
 455                 vt_cons[fg_console].vt_mode.frsig = 0;
 456                 vt_cons[fg_console].vt_pid = -1;
 457                 vt_cons[fg_console].vt_newvt = -1;
 458                 /*
 459                  * Fall through to normal (VT_AUTO) handling of the switch...
 460                  */
 461         }
 462 
 463         /*
 464          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 465          */
 466         if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
 467                 return;
 468 
 469         complete_change_console(new_console);
 470 }
 471 
 472 void wait_for_keypress(void)
     /*  */
 473 {
 474         sleep_on(&keypress_wait);
 475 }
 476 
 477 void copy_to_cooked(struct tty_struct * tty)
     /*  */
 478 {
 479         int c, special_flag;
 480         unsigned long flags;
 481 
 482         if (!tty) {
 483                 printk("copy_to_cooked: called with NULL tty\n");
 484                 return;
 485         }
 486         if (!tty->write) {
 487                 printk("copy_to_cooked: tty %d has null write routine\n",
 488                        tty->line);
 489         }
 490         while (1) {
 491                 /*
 492                  * Check to see how much room we have left in the
 493                  * secondary queue.  Send a throttle command or abort
 494                  * if necessary.
 495                  */
 496                 c = LEFT(&tty->secondary);
 497                 if (tty->throttle && (c < SQ_THRESHOLD_LW)
 498                     && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
 499                         tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
 500                 if (c == 0)
 501                         break;
 502                 save_flags(flags); cli();
 503                 if (tty->read_q.tail != tty->read_q.head) {
 504                         c = 0xff & tty->read_q.buf[tty->read_q.tail];
 505                         special_flag = clear_bit(tty->read_q.tail,
 506                                                   &tty->readq_flags);
 507                         tty->read_q.tail = (tty->read_q.tail + 1) &
 508                                 (TTY_BUF_SIZE-1);
 509                         restore_flags(flags);
 510                 } else {
 511                         restore_flags(flags);
 512                         break;
 513                 }
 514                 if (special_flag) {
 515                         tty->char_error = c & 3;
 516                         continue;
 517                 }
 518                 if (tty->char_error) {
 519                         if (tty->char_error == TTY_BREAK) {
 520                                 tty->char_error = 0;
 521                                 if (I_IGNBRK(tty))
 522                                         continue;
 523                                 if (I_PARMRK(tty)) {
 524                                         put_tty_queue('\377', &tty->secondary);
 525                                         put_tty_queue('\0', &tty->secondary);
 526                                 }
 527                                 put_tty_queue('\0', &tty->secondary);
 528                                 continue;
 529                         }
 530                         /* If not a break, then a parity or frame error */
 531                         tty->char_error = 0;
 532                         if (I_IGNPAR(tty)) {
 533                                 continue;
 534                         }
 535                         if (I_PARMRK(tty)) {
 536                                 put_tty_queue('\377', &tty->secondary);
 537                                 put_tty_queue('\0', &tty->secondary);
 538                                 put_tty_queue(c, &tty->secondary);
 539                         } else
 540                                 put_tty_queue('\0', &tty->secondary);
 541                         continue;
 542                 }
 543                 if (I_STRP(tty))
 544                         c &= 0x7f;
 545                 else if (I_PARMRK(tty) && (c == '\377'))
 546                         put_tty_queue('\377', &tty->secondary);
 547                 if (c==13) {
 548                         if (I_CRNL(tty))
 549                                 c=10;
 550                         else if (I_NOCR(tty))
 551                                 continue;
 552                 } else if (c==10 && I_NLCR(tty))
 553                         c=13;
 554                 if (I_UCLC(tty))
 555                         c=tolower(c);
 556                 if (c == __DISABLED_CHAR)
 557                         tty->lnext = 1;
 558                 if (L_CANON(tty) && !tty->lnext) {
 559                         if (c == KILL_CHAR(tty) || c == WERASE_CHAR(tty)) {
 560                                 int seen_alnums =
 561                                   (c == WERASE_CHAR(tty)) ? 0 : -1;
 562 
 563                                 /* deal with killing the input line */
 564                                 while(!(EMPTY(&tty->secondary) ||
 565                                         (c=LAST(&tty->secondary))==10 ||
 566                                         ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 567                                          (c==EOF_CHAR(tty))))) {
 568                                         /* if killing just a word, kill all
 569                                            non-alnum chars, then all alnum
 570                                            chars.  */
 571                                         if (seen_alnums >= 0) {
 572                                                 if (isalnum(c))
 573                                                         seen_alnums++;
 574                                                 else if (seen_alnums)
 575                                                         break;
 576                                         }
 577                                         if (L_ECHO(tty)) {
 578                                                 if (c<32) {
 579                                                         put_tty_queue('\b', &tty->write_q);
 580                                                         put_tty_queue(' ', &tty->write_q);
 581                                                         put_tty_queue('\b',&tty->write_q);
 582                                                 }
 583                                                 put_tty_queue('\b',&tty->write_q);
 584                                                 put_tty_queue(' ',&tty->write_q);
 585                                                 put_tty_queue('\b',&tty->write_q);
 586                                         }
 587                                         DEC(tty->secondary.head);
 588                                 }
 589                                 continue;
 590                         }
 591                         if (c == ERASE_CHAR(tty)) {
 592                                 if (EMPTY(&tty->secondary) ||
 593                                    (c=LAST(&tty->secondary))==10 ||
 594                                    ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 595                                     (c==EOF_CHAR(tty))))
 596                                         continue;
 597                                 if (L_ECHO(tty)) {
 598                                         if (c<32) {
 599                                                 put_tty_queue('\b',&tty->write_q);
 600                                                 put_tty_queue(' ',&tty->write_q);
 601                                                 put_tty_queue('\b',&tty->write_q);
 602                                         }
 603                                         put_tty_queue('\b',&tty->write_q);
 604                                         put_tty_queue(' ',&tty->write_q);
 605                                         put_tty_queue('\b',&tty->write_q);
 606                                 }
 607                                 DEC(tty->secondary.head);
 608                                 continue;
 609                         }
 610                         if (c == LNEXT_CHAR(tty)) {
 611                                 tty->lnext = 1;
 612                                 if (L_ECHO(tty)) {
 613                                         put_tty_queue('^',&tty->write_q);
 614                                         put_tty_queue('\b',&tty->write_q);
 615                                 }
 616                                 continue;
 617                         }
 618                 }
 619                 if (I_IXON(tty) && !tty->lnext) {
 620                         if (c == STOP_CHAR(tty)) {
 621                                 tty->ctrl_status &= ~(TIOCPKT_START);
 622                                 tty->ctrl_status |= TIOCPKT_STOP;
 623                                 tty->stopped=1;
 624                                 if (tty->stop)
 625                                         (tty->stop)(tty);
 626                                 if (IS_A_CONSOLE(tty->line)) {
 627                                         set_vc_kbd_flag(kbd_table + fg_console, VC_SCROLLOCK);
 628                                         set_leds();
 629                                 }
 630                                 continue;
 631                         }
 632                         if (((I_IXANY(tty)) && tty->stopped) ||
 633                             (c == START_CHAR(tty))) {
 634                                 tty->ctrl_status &= ~(TIOCPKT_STOP);
 635                                 tty->ctrl_status |= TIOCPKT_START;
 636                                 tty->stopped=0;
 637                                 if (tty->start)
 638                                         (tty->start)(tty);
 639                                 if (IS_A_CONSOLE(tty->line)) {
 640                                         clr_vc_kbd_flag(kbd_table + fg_console, VC_SCROLLOCK);
 641                                         set_leds();
 642                                 }
 643                                 continue;
 644                         }
 645                 }
 646                 if (L_ISIG(tty) && !tty->lnext) {
 647                         if (c == INTR_CHAR(tty)) {
 648                                 kill_pg(tty->pgrp, SIGINT, 1);
 649                                 if (! _L_FLAG(tty, NOFLSH)) {
 650                                   flush_input(tty);
 651                                   flush_output(tty);
 652                                 }
 653                                 continue;
 654                         }
 655                         if (c == QUIT_CHAR(tty)) {
 656                                 kill_pg(tty->pgrp, SIGQUIT, 1);
 657                                 if (! _L_FLAG(tty, NOFLSH)) {
 658                                   flush_input(tty);
 659                                   flush_output(tty);
 660                                 }
 661                                 continue;
 662                         }
 663                         if (c == SUSPEND_CHAR(tty)) {
 664                                 if (!is_orphaned_pgrp(tty->pgrp)) {
 665                                         kill_pg(tty->pgrp, SIGTSTP, 1);
 666                                         if (! _L_FLAG(tty, NOFLSH)) {
 667                                           flush_input(tty);
 668                                           flush_output(tty);
 669                                         }
 670                                 }
 671                                 continue;
 672                         }
 673                 }
 674                 if (c==10 || (EOF_CHAR(tty) != __DISABLED_CHAR &&
 675                     c==EOF_CHAR(tty)))
 676                         tty->secondary.data++;
 677                 if ((c==10) && (L_ECHO(tty) || (L_CANON(tty) && L_ECHONL(tty)))) {
 678                         put_tty_queue('\n',&tty->write_q);
 679                         put_tty_queue('\r',&tty->write_q);
 680                 } else if (L_ECHO(tty)) {
 681                         if (c<32 && L_ECHOCTL(tty)) {
 682                                 put_tty_queue('^',&tty->write_q);
 683                                 put_tty_queue(c+'A'-1, &tty->write_q);
 684                                 if (EOF_CHAR(tty) != __DISABLED_CHAR &&
 685                                     c==EOF_CHAR(tty) && !tty->lnext) {
 686                                         put_tty_queue('\b',&tty->write_q);
 687                                         put_tty_queue('\b',&tty->write_q);
 688                                 }
 689                         } else
 690                                 put_tty_queue(c, &tty->write_q);
 691                 }
 692                 tty->lnext = 0;
 693                 put_tty_queue(c, &tty->secondary);
 694         }
 695         TTY_WRITE_FLUSH(tty);
 696         if (!EMPTY(&tty->secondary))
 697                 wake_up_interruptible(&tty->secondary.proc_list);
 698         if (tty->write_q.proc_list && LEFT(&tty->write_q) > TTY_BUF_SIZE/2)
 699                 wake_up_interruptible(&tty->write_q.proc_list);
 700         if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
 701             && clear_bit(TTY_RQ_THROTTLED, &tty->flags))
 702                 tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
 703         if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 704             && clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 705                 tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 706 }
 707 
 708 int is_ignored(int sig)
     /*  */
 709 {
 710         return ((current->blocked & (1<<(sig-1))) ||
 711                 (current->sigaction[sig-1].sa_handler == SIG_IGN));
 712 }
 713 
 714 static int available_canon_input(struct tty_struct *);
 715 static void __wait_for_canon_input(struct file * file, struct tty_struct *);
 716 
 717 static void wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 718 {
 719         if (!available_canon_input(tty)) {
 720                 if (current->signal & ~current->blocked)
 721                         return;
 722                 __wait_for_canon_input(file, tty);
 723         }
 724 }
 725 
 726 static int read_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 727 {
 728         struct wait_queue wait = { current, NULL };
 729         int c;
 730         char * b=buf;
 731         int minimum,time;
 732 
 733         if (L_CANON(tty))
 734                 minimum = time = current->timeout = 0;
 735         else {
 736                 time = 10L*tty->termios->c_cc[VTIME];
 737                 minimum = tty->termios->c_cc[VMIN];
 738                 if (minimum)
 739                         current->timeout = 0xffffffff;
 740                 else {
 741                         if (time)
 742                                 current->timeout = time + jiffies;
 743                         else
 744                                 current->timeout = 0;
 745                         time = 0;
 746                         minimum = 1;
 747                 }
 748         }
 749         if (file->f_flags & O_NONBLOCK) {
 750                 time = current->timeout = 0;
 751                 if (L_CANON(tty) && !available_canon_input(tty))
 752                                 return -EAGAIN;
 753         } else if (L_CANON(tty)) {
 754                 wait_for_canon_input(file, tty);
 755                 if (current->signal & ~current->blocked)
 756                         return -ERESTARTSYS;
 757         }
 758         if (minimum>nr)
 759                 minimum = nr;
 760 
 761         /* deal with packet mode:  First test for status change */
 762         if (tty->packet && tty->link && tty->link->ctrl_status) {
 763                 put_fs_byte (tty->link->ctrl_status, b);
 764                 tty->link->ctrl_status = 0;
 765                 return 1;
 766         }
 767           
 768         /* now bump the buffer up one. */
 769         if (tty->packet) {
 770                 put_fs_byte (0,b++);
 771                 nr--;
 772                 /* this really shouldn't happen, but we need to 
 773                 put it here. */
 774                 if (nr == 0)
 775                         return 1;
 776         }
 777         add_wait_queue(&tty->secondary.proc_list, &wait);
 778         while (nr>0) {
 779                 if (tty_hung_up_p(file)) {
 780                         file->f_flags &= ~O_NONBLOCK;
 781                         break;  /* force read() to return 0 */
 782                 }
 783                 TTY_READ_FLUSH(tty);
 784                 if (tty->link)
 785                         TTY_WRITE_FLUSH(tty->link);
 786                 while (nr > 0 && ((c = get_tty_queue(&tty->secondary)) >= 0)) {
 787                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 788                              c==EOF_CHAR(tty)) || c==10)
 789                                 tty->secondary.data--;
 790                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 791                              c==EOF_CHAR(tty)) && L_CANON(tty))
 792                                 break;
 793                         put_fs_byte(c,b++);
 794                         nr--;
 795                         if (time)
 796                                 current->timeout = time+jiffies;
 797                         if (c==10 && L_CANON(tty))
 798                                 break;
 799                 };
 800                 wake_up_interruptible(&tty->read_q.proc_list);
 801                 /*
 802                  * If there is enough space in the secondary queue
 803                  * now, let the low-level driver know.
 804                  */
 805                 if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 806                     && clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 807                         tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 808                 if (tty->link) {
 809                         if (IS_A_PTY_MASTER(tty->line)) {
 810                                 if ((tty->flags & (1 << TTY_SLAVE_OPENED))
 811                                     && tty->link->count <= 1) {
 812                                         file->f_flags &= ~O_NONBLOCK;
 813                                         break;
 814                                 }
 815                         } else if (!tty->link->count) {
 816                                 file->f_flags &= ~O_NONBLOCK;
 817                                 break;
 818                         }
 819                 }
 820                 if (b-buf >= minimum || !current->timeout)
 821                         break;
 822                 if (current->signal & ~current->blocked) 
 823                         break;
 824                 TTY_READ_FLUSH(tty);
 825                 if (tty->link)
 826                         TTY_WRITE_FLUSH(tty->link);
 827                 if (!EMPTY(&tty->secondary))
 828                         continue;
 829                 current->state = TASK_INTERRUPTIBLE;
 830                 if (EMPTY(&tty->secondary))
 831                         schedule();
 832                 current->state = TASK_RUNNING;
 833         }
 834         remove_wait_queue(&tty->secondary.proc_list, &wait);
 835         TTY_READ_FLUSH(tty);
 836         if (tty->link && tty->link->write)
 837                 TTY_WRITE_FLUSH(tty->link);
 838         current->timeout = 0;
 839 
 840         /* packet mode sticks in an extra 0.  If that's all we've got,
 841            we should count it a zero bytes. */
 842         if (tty->packet) {
 843                 if ((b-buf) > 1)
 844                         return b-buf;
 845         } else {
 846                 if (b-buf)
 847                         return b-buf;
 848         }
 849 
 850         if (current->signal & ~current->blocked)
 851                 return -ERESTARTSYS;
 852         if (file->f_flags & O_NONBLOCK)
 853                 return -EAGAIN;
 854         if (IS_A_PTY_MASTER(tty->line))
 855                 return -EIO;
 856         return 0;
 857 }
 858 
 859 static void __wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 860 {
 861         struct wait_queue wait = { current, NULL };
 862 
 863         add_wait_queue(&tty->secondary.proc_list, &wait);
 864         while (1) {
 865                 current->state = TASK_INTERRUPTIBLE;
 866                 if (available_canon_input(tty))
 867                         break;
 868                 if (current->signal & ~current->blocked)
 869                         break;
 870                 if (tty_hung_up_p(file))
 871                         break;
 872                 schedule();
 873         }
 874         current->state = TASK_RUNNING;
 875         remove_wait_queue(&tty->secondary.proc_list, &wait);
 876 }
 877 
 878 static int available_canon_input(struct tty_struct * tty)
     /*  */
 879 {
 880         TTY_READ_FLUSH(tty);
 881         if (tty->link)
 882                 if (tty->link->count)
 883                         TTY_WRITE_FLUSH(tty->link);
 884                 else
 885                         return 1;
 886         if (FULL(&tty->read_q))
 887                 return 1;
 888         if (tty->secondary.data)
 889                 return 1;
 890         return 0;
 891 }
 892 
 893 static int write_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 894 {
 895         struct wait_queue wait = { current, NULL };
 896         char c, *b=buf;
 897 
 898         if (nr < 0)
 899                 return -EINVAL;
 900         if (!nr)
 901                 return 0;
 902         add_wait_queue(&tty->write_q.proc_list, &wait);
 903         while (nr>0) {
 904                 if (current->signal & ~current->blocked)
 905                         break;
 906                 if (tty_hung_up_p(file))
 907                         break;
 908                 if (tty->link && !tty->link->count) {
 909                         send_sig(SIGPIPE,current,0);
 910                         break;
 911                 }
 912                 current->state = TASK_INTERRUPTIBLE;
 913                 if (FULL(&tty->write_q)) {
 914                         TTY_WRITE_FLUSH(tty);
 915                         if (FULL(&tty->write_q))
 916                                 schedule();
 917                         current->state = TASK_RUNNING;
 918                         continue;
 919                 }
 920                 current->state = TASK_RUNNING;
 921                 while (nr>0 && !FULL(&tty->write_q)) {
 922                         c=get_fs_byte(b);
 923                         if (O_POST(tty)) {
 924                                 switch (c) {
 925                                         case '\n':
 926                                                 if (O_NLRET(tty)) {
 927                                                         tty->column = 0;
 928                                                 }
 929                                                 if (O_NLCR(tty)) {
 930                                                         if (!set_bit(TTY_CR_PENDING,&tty->flags)) {
 931                                                                 c = '\r';
 932                                                                 tty->column = 0;
 933                                                                 b--; nr++;
 934                                                         } else {
 935                                                                 clear_bit(TTY_CR_PENDING,&tty->flags);
 936                                                         }
 937                                                 }
 938                                                 break;
 939                                         case '\r':
 940                                                 if (O_NOCR(tty) && tty->column == 0) {
 941                                                         b++; nr--;
 942                                                         continue;
 943                                                 }
 944                                                 if (O_CRNL(tty)) {
 945                                                         c = '\n';
 946                                                         if (O_NLRET(tty))
 947                                                                 tty->column = 0;
 948                                                         break;
 949                                                 }
 950                                                 tty->column = 0;
 951                                                 break;
 952                                         case '\t':
 953                                                 if (O_TABDLY(tty) == XTABS) {
 954                                                         c = ' ';
 955                                                         tty->column++;
 956                                                         if (tty->column % 8 != 0) {
 957                                                                 b--; nr++;
 958                                                         }
 959                                                 }
 960                                                 break;
 961                                         case '\b':
 962                                                 tty->column--;
 963                                                 break;
 964                                         default:
 965                                                 if (O_LCUC(tty))
 966                                                         c = toupper(c);
 967                                                 tty->column++;
 968                                                 break;
 969                                 }
 970                         }
 971                         b++; nr--;
 972                         put_tty_queue(c,&tty->write_q);
 973                 }
 974                 if (need_resched)
 975                         schedule();
 976         }
 977         remove_wait_queue(&tty->write_q.proc_list, &wait);
 978         TTY_WRITE_FLUSH(tty);
 979         if (b-buf)
 980                 return b-buf;
 981         if (tty->link && !tty->link->count)
 982                 return -EPIPE;
 983         if (current->signal & ~current->blocked)
 984                 return -ERESTARTSYS;
 985         return 0;
 986 }
 987 
 988 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 989 {
 990         int i, dev;
 991         struct tty_struct * tty;
 992 
 993         dev = file->f_rdev;
 994         if (MAJOR(dev) != 4) {
 995                 printk("tty_read: bad pseudo-major nr #%d\n", MAJOR(dev));
 996                 return -EINVAL;
 997         }
 998         dev = MINOR(dev);
 999         tty = TTY_TABLE(dev);
1000         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
1001                 return -EIO;
1002         if ((inode->i_rdev != 0x0400) && /* don't stop on /dev/console */
1003             (tty->pgrp > 0) &&
1004             (current->tty == dev) &&
1005             (tty->pgrp != current->pgrp))
1006                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
1007                         return -EIO;
1008                 else {
1009                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
1010                         return -ERESTARTSYS;
1011                 }
1012         if (ldiscs[tty->disc].read)
1013                 i = (ldiscs[tty->disc].read)(tty,file,buf,count);
1014         else
1015                 i = -EIO;
1016         if (i > 0)
1017                 inode->i_atime = CURRENT_TIME;
1018         return i;
1019 }
1020 
1021 static int tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
1022 {
1023         int dev, i, is_console;
1024         struct tty_struct * tty;
1025 
1026         dev = file->f_rdev;
1027         is_console = (inode->i_rdev == 0x0400);
1028         if (MAJOR(dev) != 4) {
1029                 printk("tty_write: pseudo-major != 4\n");
1030                 return -EINVAL;
1031         }
1032         dev = MINOR(dev);
1033         if (is_console && redirect)
1034                 tty = redirect;
1035         else
1036                 tty = TTY_TABLE(dev);
1037         if (!tty || !tty->write || (tty->flags & (1 << TTY_IO_ERROR)))
1038                 return -EIO;
1039         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
1040             (current->tty == dev) && (tty->pgrp != current->pgrp)) {
1041                 if (is_orphaned_pgrp(current->pgrp))
1042                         return -EIO;
1043                 if (!is_ignored(SIGTTOU)) {
1044                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
1045                         return -ERESTARTSYS;
1046                 }
1047         }
1048         if (ldiscs[tty->disc].write)
1049                 i = (ldiscs[tty->disc].write)(tty,file,buf,count);
1050         else
1051                 i = -EIO;
1052         if (i > 0)
1053                 inode->i_mtime = CURRENT_TIME;
1054         return i;
1055 }
1056 
1057 /*
1058  * This is so ripe with races that you should *really* not touch this
1059  * unless you know exactly what you are doing. All the changes have to be
1060  * made atomically, or there may be incorrect pointers all over the place.
1061  */
1062 static int init_dev(int dev)
     /*  */
1063 {
1064         struct tty_struct *tty, *o_tty;
1065         struct termios *tp, *o_tp, *ltp, *o_ltp;
1066         int retval;
1067         int o_dev;
1068 
1069         o_dev = PTY_OTHER(dev);
1070         tty = o_tty = NULL;
1071         tp = o_tp = NULL;
1072         ltp = o_ltp = NULL;
1073 repeat:
1074         retval = -EAGAIN;
1075         if (IS_A_PTY_MASTER(dev) && tty_table[dev] && tty_table[dev]->count)
1076                 goto end_init;
1077         retval = -ENOMEM;
1078         if (!tty_table[dev] && !tty) {
1079                 if (!(tty = (struct tty_struct*) get_free_page(GFP_KERNEL)))
1080                         goto end_init;
1081                 initialize_tty_struct(dev, tty);
1082                 goto repeat;
1083         }
1084         if (!tty_termios[dev] && !tp) {
1085                 tp = (struct termios *) kmalloc(sizeof(struct termios),
1086                                                 GFP_KERNEL);
1087                 if (!tp)
1088                         goto end_init;
1089                 initialize_termios(dev, tp);
1090                 goto repeat;
1091         }
1092         if (!termios_locked[dev] && !ltp) {
1093                 ltp = (struct termios *) kmalloc(sizeof(struct termios),
1094                                                  GFP_KERNEL);
1095                 if (!ltp)
1096                         goto end_init;
1097                 memset(ltp, 0, sizeof(struct termios));
1098                 goto repeat;
1099         }
1100         if (IS_A_PTY(dev)) {
1101                 if (!tty_table[o_dev] && !o_tty) {
1102                         o_tty = (struct tty_struct *)
1103                                 get_free_page(GFP_KERNEL);
1104                         if (!o_tty)
1105                                 goto end_init;
1106                         initialize_tty_struct(o_dev, o_tty);
1107                         goto repeat;
1108                 }
1109                 if (!tty_termios[o_dev] && !o_tp) {
1110                         o_tp = (struct termios *)
1111                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
1112                         if (!o_tp)
1113                                 goto end_init;
1114                         initialize_termios(o_dev, o_tp);
1115                         goto repeat;
1116                 }
1117                 if (!termios_locked[o_dev] && !o_ltp) {
1118                         o_ltp = (struct termios *)
1119                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
1120                         if (!o_ltp)
1121                                 goto end_init;
1122                         memset(o_ltp, 0, sizeof(struct termios));
1123                         goto repeat;
1124                 }
1125                 
1126         }
1127         /* Now we have allocated all the structures: update all the pointers.. */
1128         if (!tty_termios[dev]) {
1129                 tty_termios[dev] = tp;
1130                 tp = NULL;
1131         }
1132         if (!tty_table[dev]) {
1133                 tty->termios = tty_termios[dev];
1134                 tty_table[dev] = tty;
1135                 tty = NULL;
1136         }
1137         if (!termios_locked[dev]) {
1138                 termios_locked[dev] = ltp;
1139                 ltp = NULL;
1140         }
1141         if (IS_A_PTY(dev)) {
1142                 if (!tty_termios[o_dev]) {
1143                         tty_termios[o_dev] = o_tp;
1144                         o_tp = NULL;
1145                 }
1146                 if (!termios_locked[o_dev]) {
1147                         termios_locked[o_dev] = o_ltp;
1148                         o_ltp = NULL;
1149                 }
1150                 if (!tty_table[o_dev]) {
1151                         o_tty->termios = tty_termios[o_dev];
1152                         tty_table[o_dev] = o_tty;
1153                         o_tty = NULL;
1154                 }
1155                 tty_table[dev]->link = tty_table[o_dev];
1156                 tty_table[o_dev]->link = tty_table[dev];
1157         }
1158         tty_table[dev]->count++;
1159         if (IS_A_PTY_MASTER(dev))
1160                 tty_table[o_dev]->count++;
1161         retval = 0;
1162 end_init:
1163         if (tty)
1164                 free_page((unsigned long) tty);
1165         if (o_tty)
1166                 free_page((unsigned long) o_tty);
1167         if (tp)
1168                 kfree_s(tp, sizeof(struct termios));
1169         if (o_tp)
1170                 kfree_s(o_tp, sizeof(struct termios));
1171         if (ltp)
1172                 kfree_s(ltp, sizeof(struct termios));
1173         if (o_ltp)
1174                 kfree_s(o_ltp, sizeof(struct termios));
1175         return retval;
1176 }
1177 
1178 /*
1179  * Even releasing the tty structures is a tricky business.. We have
1180  * to be very careful that the structures are all released at the
1181  * same time, as interrupts might otherwise get the wrong pointers.
1182  */
1183 static void release_dev(int dev, struct file * filp)
     /*  */
1184 {
1185         struct tty_struct *tty, *o_tty;
1186         struct termios *tp, *o_tp;
1187         struct task_struct **p;
1188 
1189         tty = tty_table[dev];
1190         tp = tty_termios[dev];
1191         o_tty = NULL;
1192         o_tp = NULL;
1193         if (!tty) {
1194                 printk("release_dev: tty_table[%d] was NULL\n", dev);
1195                 return;
1196         }
1197         if (!tp) {
1198                 printk("release_dev: tty_termios[%d] was NULL\n", dev);
1199                 return;
1200         }
1201         if (IS_A_PTY(dev)) {
1202                 o_tty = tty_table[PTY_OTHER(dev)];
1203                 o_tp = tty_termios[PTY_OTHER(dev)];
1204                 if (!o_tty) {
1205                         printk("release_dev: pty pair(%d) was NULL\n", dev);
1206                         return;
1207                 }
1208                 if (!o_tp) {
1209                         printk("release_dev: pty pair(%d) termios was NULL\n", dev);
1210                         return;
1211                 }
1212                 if (tty->link != o_tty || o_tty->link != tty) {
1213                         printk("release_dev: bad pty pointers\n");
1214                         return;
1215                 }
1216         }
1217         tty->write_data_cnt = 0; /* Clear out pending trash */
1218         if (tty->close)
1219                 tty->close(tty, filp);
1220         if (IS_A_PTY_MASTER(dev)) {
1221                 if (--tty->link->count < 0) {
1222                         printk("release_dev: bad tty slave count (dev = %d): %d\n",
1223                                dev, tty->count);
1224                         tty->link->count = 0;
1225                 }
1226         }
1227         if (--tty->count < 0) {
1228                 printk("release_dev: bad tty_table[%d]->count: %d\n",
1229                        dev, tty->count);
1230                 tty->count = 0;
1231         }
1232         if (tty->count)
1233                 return;
1234 
1235         /*
1236          * Make sure there aren't any processes that still think this
1237          * tty is their controlling tty.
1238          */
1239         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1240                 if ((*p) && (*p)->tty == tty->line)
1241                 (*p)->tty = -1;
1242         }
1243 
1244         if (ldiscs[tty->disc].close != NULL)
1245                 ldiscs[tty->disc].close(tty);
1246 
1247         if (o_tty) {
1248                 if (o_tty->count)
1249                         return;
1250                 else {
1251                         tty_table[PTY_OTHER(dev)] = NULL;
1252                         tty_termios[PTY_OTHER(dev)] = NULL;
1253                 }
1254         }
1255         tty_table[dev] = NULL;
1256         if (IS_A_PTY(dev)) {
1257                 tty_termios[dev] = NULL;
1258                 kfree_s(tp, sizeof(struct termios));
1259         }
1260         if (tty == redirect || o_tty == redirect)
1261                 redirect = NULL;
1262         free_page((unsigned long) tty);
1263         if (o_tty)
1264                 free_page((unsigned long) o_tty);
1265         if (o_tp)
1266                 kfree_s(o_tp, sizeof(struct termios));
1267 }
1268 
1269 /*
1270  * tty_open and tty_release keep up the tty count that contains the
1271  * number of opens done on a tty. We cannot use the inode-count, as
1272  * different inodes might point to the same tty.
1273  *
1274  * Open-counting is needed for pty masters, as well as for keeping
1275  * track of serial lines: DTR is dropped when the last close happens.
1276  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1277  *
1278  * The termios state of a pty is reset on first open so that
1279  * settings don't persist across reuse.
1280  */
1281 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1282 {
1283         struct tty_struct *tty;
1284         int major, minor;
1285         int noctty, retval;
1286 
1287         minor = MINOR(inode->i_rdev);
1288         major = MAJOR(inode->i_rdev);
1289         noctty = filp->f_flags & O_NOCTTY;
1290         if (major == 5) {
1291                 if (!minor) {
1292                         major = 4;
1293                         minor = current->tty;
1294                 }
1295                 noctty = 1;
1296         } else if (major == 4) {
1297                 if (!minor) {
1298                         minor = fg_console + 1;
1299                         noctty = 1;
1300                 }
1301         } else {
1302                 printk("Bad major #%d in tty_open\n", MAJOR(inode->i_rdev));
1303                 return -ENODEV;
1304         }
1305         if (minor <= 0)
1306                 return -ENXIO;
1307         if (IS_A_PTY_MASTER(minor))
1308                 noctty = 1;
1309         filp->f_rdev = (major << 8) | minor;
1310         retval = init_dev(minor);
1311         if (retval)
1312                 return retval;
1313         tty = tty_table[minor];
1314 
1315         /* clean up the packet stuff. */
1316         /*
1317          *  Why is this not done in init_dev?  Right here, if another 
1318          * process opens up a tty in packet mode, all the packet 
1319          * variables get cleared.  Come to think of it, is anything 
1320          * using the packet mode at all???  - Ted, 1/27/93
1321          */
1322         tty->ctrl_status = 0;
1323         tty->packet = 0;
1324 
1325         if (tty->open) {
1326                 retval = tty->open(tty, filp);
1327         } else {
1328                 retval = -ENODEV;
1329         }
1330         if (retval) {
1331                 release_dev(minor, filp);
1332                 return retval;
1333         }
1334         if (!noctty &&
1335             current->leader &&
1336             current->tty<0 &&
1337             tty->session==0) {
1338                 current->tty = minor;
1339                 tty->session = current->session;
1340                 tty->pgrp = current->pgrp;
1341         }
1342         filp->f_rdev = 0x0400 | minor; /* Set it to something normal */
1343         return 0;
1344 }
1345 
1346 /*
1347  * Note that releasing a pty master also releases the child, so
1348  * we have to make the redirection checks after that and on both
1349  * sides of a pty.
1350  */
1351 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1352 {
1353         int dev;
1354 
1355         dev = filp->f_rdev;
1356         if (MAJOR(dev) != 4) {
1357                 printk("tty_release: tty pseudo-major != 4\n");
1358                 return;
1359         }
1360         dev = MINOR(filp->f_rdev);
1361         if (!dev) {
1362                 printk("tty_release: bad f_rdev\n");
1363                 return;
1364         }
1365         release_dev(dev, filp);
1366 }
1367 
1368 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1369 {
1370         int dev;
1371         struct tty_struct * tty;
1372 
1373         dev = filp->f_rdev;
1374         if (MAJOR(dev) != 4) {
1375                 printk("tty_select: tty pseudo-major != 4\n");
1376                 return 0;
1377         }
1378         dev = MINOR(filp->f_rdev);
1379         tty = TTY_TABLE(dev);
1380         if (!tty) {
1381                 printk("tty_select: tty struct for dev %d was NULL\n", dev);
1382                 return 0;
1383         }
1384         switch (sel_type) {
1385                 case SEL_IN:
1386                         if (L_CANON(tty)) {
1387                                 if (available_canon_input(tty))
1388                                         return 1;
1389                         } else if (!EMPTY(&tty->secondary))
1390                                 return 1;
1391                         if (tty->link) {
1392                                 if (IS_A_PTY_MASTER(tty->line)) {
1393                                         if ((tty->flags & (1 << TTY_SLAVE_OPENED))
1394                                             && tty->link->count <= 1)
1395                                                 return 1;
1396                                 } else {
1397                                         if (!tty->link->count)
1398                                                 return 1;
1399                                 }
1400                         }
1401 
1402                         /* see if the status byte can be read. */
1403                         if (tty->packet && tty->link &&
1404                             tty->link->status_changed)
1405                                 return 1;
1406 
1407                         select_wait(&tty->secondary.proc_list, wait);
1408                         return 0;
1409                 case SEL_OUT:
1410                         if (!FULL(&tty->write_q))
1411                                 return 1;
1412                         select_wait(&tty->write_q.proc_list, wait);
1413                         return 0;
1414                 case SEL_EX:
1415                         if (tty->link) {
1416                                 if (IS_A_PTY_MASTER(tty->line)) {
1417                                         if ((tty->flags & (1 << TTY_SLAVE_OPENED))
1418                                             && tty->link->count <= 1)
1419                                                 return 1;
1420                                 } else {
1421                                         if (!tty->link->count)
1422                                                 return 1;
1423                                 }
1424                         }
1425                         return 0;
1426         }
1427         return 0;
1428 }
1429 
1430 /*
1431  * This implements the "Secure Attention Key" ---  the idea is to
1432  * prevent trojan horses by killing all processes associated with this
1433  * tty when the user hits the "Secure Attention Key".  Required for
1434  * super-paranoid applications --- see the Orange Book for more details.
1435  * 
1436  * This code could be nicer; ideally it should send a HUP, wait a few
1437  * seconds, then send a INT, and then a KILL signal.  But you then
1438  * have to coordinate with the init process, since all processes associated
1439  * with the current tty must be dead before the new getty is allowed
1440  * to spawn.
1441  */
1442 void do_SAK( struct tty_struct *tty)
     /*  */
1443 {
1444         struct task_struct **p;
1445         int line = tty->line;
1446         int session = tty->session;
1447         int             i;
1448         struct file     *filp;
1449         
1450         flush_input(tty);
1451         flush_output(tty);
1452         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1453                 if (!(*p))
1454                         continue;
1455                 if (((*p)->tty == line) ||
1456                     ((session > 0) && ((*p)->session == session)))
1457                         send_sig(SIGKILL, *p, 1);
1458                 else {
1459                         for (i=0; i < NR_OPEN; i++) {
1460                                 filp = (*p)->filp[i];
1461                                 if (filp && (filp->f_op == &tty_fops) &&
1462                                     (MINOR(filp->f_rdev) == line)) {
1463                                         send_sig(SIGKILL, *p, 1);
1464                                         break;
1465                                 }
1466                         }
1467                 }
1468         }
1469 }
1470 
1471 /*
1472  * This routine allows a kernel routine to send a large chunk of data
1473  * to a particular tty; if all of the data can be queued up for ouput
1474  * immediately, tty_write_data() will return 0.  If, however, not all
1475  * of the data can be immediately queued for delivery, the number of
1476  * bytes left to be queued up will be returned, and the rest of the
1477  * data will be queued up when there is room.  The callback function
1478  * will be called (with the argument callarg) when the last of the
1479  * data is finally in the queue.
1480  *
1481  * Note that the callback routine will _not_ be called if all of the
1482  * data could be queued immediately.  This is to avoid a problem with
1483  * the kernel stack getting too deep, which might happen if the
1484  * callback routine calls tty_write_data with itself as an argument.
1485  */
1486 int tty_write_data(struct tty_struct *tty, char *bufp, int buflen,
     /*  */
1487                     void (*callback)(void * data), void * callarg)
1488 {
1489         int head, tail, count;
1490         unsigned long flags;
1491         char *p;
1492 
1493 #define VLEFT ((tail-head-1)&(TTY_BUF_SIZE-1))
1494 
1495         save_flags(flags);
1496         cli();
1497         if (tty->write_data_cnt) {
1498                 restore_flags(flags);
1499                 return -EBUSY;
1500         }
1501 
1502         head = tty->write_q.head;
1503         tail = tty->write_q.tail;
1504         count = buflen;
1505         p = bufp;
1506 
1507         while (count && VLEFT > 0) {
1508                 tty->write_q.buf[head++] = *p++;
1509                 head &= TTY_BUF_SIZE-1;
1510                 count--;
1511         }
1512         tty->write_q.head = head;
1513         if (count) {
1514                 tty->write_data_cnt = count;
1515                 tty->write_data_ptr = (unsigned char *) p;
1516                 tty->write_data_callback = callback;
1517                 tty->write_data_arg = callarg;
1518         }
1519         restore_flags(flags);
1520         tty->write(tty);
1521         return count;
1522 }
1523 
1524 /*
1525  * This routine routine is called after an interrupt has drained a
1526  * tty's write queue, so that there is more space for data waiting to
1527  * be sent in tty->write_data_ptr.
1528  *
1529  * tty_check_write[8] is a bitstring which indicates which ttys
1530  * needs to be processed.
1531  */
1532 void tty_bh_routine(void * unused)
     /*  */
1533 {
1534         int     i, j, line, mask;
1535         int     head, tail, count;
1536         unsigned char * p;
1537         struct tty_struct * tty;
1538 
1539         for (i = 0, line = 0; i < MAX_TTYS / 32; i++) {
1540                 if (!tty_check_write[i]) {
1541                         line += 32;
1542                         continue;
1543                 }
1544                 for (j=0, mask=0; j < 32; j++, line++, mask <<= 1) {
1545                         if (clear_bit(j, &tty_check_write[i])) {
1546                                 tty = tty_table[line];
1547                                 if (!tty || !tty->write_data_cnt)
1548                                         continue;
1549                                 cli();
1550                                 head = tty->write_q.head;
1551                                 tail = tty->write_q.tail;
1552                                 count = tty->write_data_cnt;
1553                                 p = tty->write_data_ptr;
1554 
1555                                 while (count && VLEFT > 0) {
1556                                         tty->write_q.buf[head++] = *p++;
1557                                         head &= TTY_BUF_SIZE-1;
1558                                         count--;
1559                                 }
1560                                 tty->write_q.head = head;
1561                                 tty->write_data_ptr = p;
1562                                 tty->write_data_cnt = count;
1563                                 sti();
1564                                 if (!count)
1565                                         (tty->write_data_callback)
1566                                                 (tty->write_data_arg);
1567                         }
1568                 }
1569         }
1570         
1571 }
1572 
1573 /*
1574  * This subroutine initializes a tty structure.  We have to set up
1575  * things correctly for each different type of tty.
1576  */
1577 static void initialize_tty_struct(int line, struct tty_struct *tty)
     /*  */
1578 {
1579         memset(tty, 0, sizeof(struct tty_struct));
1580         tty->line = line;
1581         tty->disc = N_TTY;
1582         tty->pgrp = -1;
1583         tty->winsize.ws_row = 0;
1584         tty->winsize.ws_col = 0;
1585         if (IS_A_CONSOLE(line)) {
1586                 tty->open = con_open;
1587                 tty->winsize.ws_row = video_num_lines;
1588                 tty->winsize.ws_col = video_num_columns;
1589         } else if IS_A_SERIAL(line) {
1590                 tty->open = rs_open;
1591         } else if IS_A_PTY(line) {
1592                 tty->open = pty_open;
1593         }
1594 }
1595 
1596 static void initialize_termios(int line, struct termios * tp)
     /*  */
1597 {
1598         memset(tp, 0, sizeof(struct termios));
1599         memcpy(tp->c_cc, INIT_C_CC, NCCS);
1600         if (IS_A_CONSOLE(line)) {
1601                 tp->c_iflag = ICRNL | IXON;
1602                 tp->c_oflag = OPOST | ONLCR;
1603                 tp->c_cflag = B38400 | CS8 | CREAD;
1604                 tp->c_lflag = ISIG | ICANON | ECHO |
1605                         ECHOCTL | ECHOKE;
1606         } else if (IS_A_SERIAL(line)) {
1607                 tp->c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1608                 tp->c_oflag = OPOST | ONLCR | XTABS;
1609         } else if (IS_A_PTY_MASTER(line)) {
1610                 tp->c_cflag = B9600 | CS8 | CREAD;
1611         } else if (IS_A_PTY_SLAVE(line)) {
1612                 tp->c_iflag = ICRNL | IXON;
1613                 tp->c_oflag = OPOST | ONLCR;
1614                 tp->c_cflag = B38400 | CS8 | CREAD;
1615                 tp->c_lflag = ISIG | ICANON | ECHO |
1616                         ECHOCTL | ECHOKE;
1617         }
1618 }
1619 
1620 static struct tty_ldisc tty_ldisc_N_TTY = {
1621         0,                      /* flags */
1622         NULL,                   /* open */
1623         NULL,                   /* close */
1624         read_chan,              /* read */
1625         write_chan,             /* write */
1626         NULL,                   /* ioctl */
1627         copy_to_cooked          /* handler */
1628 };
1629 
1630         
1631 long tty_init(long kmem_start)
     /*  */
1632 {
1633         int i;
1634 
1635         if (sizeof(struct tty_struct) > PAGE_SIZE)
1636                 panic("size of tty structure > PAGE_SIZE!");
1637         if (register_chrdev(4,"tty",&tty_fops))
1638                 panic("unable to get major 4 for tty device");
1639         if (register_chrdev(5,"tty",&tty_fops))
1640                 panic("unable to get major 5 for tty device");
1641         for (i=0 ; i< MAX_TTYS ; i++) {
1642                 tty_table[i] =  0;
1643                 tty_termios[i] = 0;
1644         }
1645         memset(tty_check_write, 0, sizeof(tty_check_write));
1646         bh_base[TTY_BH].routine = tty_bh_routine;
1647 
1648         /* Setup the default TTY line discipline. */
1649         memset(ldiscs, 0, sizeof(ldiscs));
1650         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1651 
1652         kmem_start = kbd_init(kmem_start);
1653         kmem_start = con_init(kmem_start);
1654         kmem_start = rs_init(kmem_start);
1655         return kmem_start;
1656 }
/* */
root/kernel/chr_drv/tty_io.c

DEFINITIONS
