drivers/char/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/major.h>
  39 #include <linux/errno.h>
  40 #include <linux/signal.h>
  41 #include <linux/fcntl.h>
  42 #include <linux/sched.h>
  43 #include <linux/tty.h>
  44 #include <linux/timer.h>
  45 #include <linux/ctype.h>
  46 #include <linux/kd.h>
  47 #include <linux/mm.h>
  48 #include <linux/string.h>
  49 #include <linux/keyboard.h>
  50 #include <linux/malloc.h>
  51 
  52 #include <asm/segment.h>
  53 #include <asm/system.h>
  54 #include <asm/bitops.h>
  55 
  56 #include "vt_kern.h"
  57 
  58 #define MAX_TTYS 256
  59 
  60 struct tty_struct *tty_table[MAX_TTYS];
  61 struct termios *tty_termios[MAX_TTYS];  /* We need to keep the termios state */
  62                                         /* around, even when a tty is closed */
  63 struct termios *termios_locked[MAX_TTYS]; /* Bitfield of locked termios flags*/
  64 struct tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
  65 int tty_check_write[MAX_TTYS/32];       /* bitfield for the bh handler */
  66 
  67 /*
  68  * fg_console is the current virtual console,
  69  * redirect is the pseudo-tty that console output
  70  * is redirected to if asked by TIOCCONS.
  71  */
  72 int fg_console = 0;
  73 struct tty_struct * redirect = NULL;
  74 struct wait_queue * keypress_wait = NULL;
  75 
  76 static void initialize_tty_struct(int line, struct tty_struct *tty);
  77 static void initialize_termios(int line, struct termios *tp);
  78 
  79 static int tty_read(struct inode *, struct file *, char *, int);
  80 static int tty_write(struct inode *, struct file *, char *, int);
  81 static int tty_select(struct inode *, struct file *, int, select_table *);
  82 static int tty_open(struct inode *, struct file *);
  83 static void tty_release(struct inode *, struct file *);
  84 
  85 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
     /*  */
  86 {
  87         if (disc < N_TTY || disc >= NR_LDISCS)
  88                 return -EINVAL;
  89         
  90         if (new_ldisc) {
  91                 ldiscs[disc] = *new_ldisc;
  92                 ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
  93         } else
  94                 memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
  95         
  96         return 0;
  97 }
  98 
  99 void put_tty_queue(char c, struct tty_queue * queue)
     /*  */
 100 {
 101         int head;
 102         unsigned long flags;
 103 
 104         save_flags(flags);
 105         cli();
 106         head = (queue->head + 1) & (TTY_BUF_SIZE-1);
 107         if (head != queue->tail) {
 108                 queue->buf[queue->head] = c;
 109                 queue->head = head;
 110         }
 111         restore_flags(flags);
 112 }
 113 
 114 int get_tty_queue(struct tty_queue * queue)
     /*  */
 115 {
 116         int result = -1;
 117         unsigned long flags;
 118 
 119         save_flags(flags);
 120         cli();
 121         if (queue->tail != queue->head) {
 122                 result = 0xff & queue->buf[queue->tail];
 123                 queue->tail = (queue->tail + 1) & (TTY_BUF_SIZE-1);
 124         }
 125         restore_flags(flags);
 126         return result;
 127 }
 128 
 129 /*
 130  * This routine copies out a maximum of buflen characters from the
 131  * read_q; it is a convenience for line disciplines so they can grab a
 132  * large block of data without calling get_tty_char directly.  It
 133  * returns the number of characters actually read. Return terminates
 134  * if an error character is read from the queue and the return value
 135  * is negated.
 136  */
 137 int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp, int buflen)
     /*  */
 138 {
 139         int     result = 0;
 140         unsigned char   *p = bufp;
 141         unsigned long flags;
 142         int head, tail;
 143         int ok = 1;
 144 
 145         save_flags(flags);
 146         cli();
 147         tail = tty->read_q.tail;
 148         head = tty->read_q.head;
 149         while ((result < buflen) && (tail!=head) && ok) {
 150                 ok = !clear_bit (tail, &tty->readq_flags);
 151                 *p++ =  tty->read_q.buf[tail++];
 152                 tail &= TTY_BUF_SIZE-1;
 153                 result++;
 154         }
 155         tty->read_q.tail = tail;
 156         restore_flags(flags);
 157         return (ok) ? result : -result;
 158 }
 159 
 160 
 161 void tty_write_flush(struct tty_struct * tty)
     /*  */
 162 {
 163         if (!tty->write || EMPTY(&tty->write_q))
 164                 return;
 165         if (set_bit(TTY_WRITE_BUSY,&tty->flags))
 166                 return;
 167         tty->write(tty);
 168         if (!clear_bit(TTY_WRITE_BUSY,&tty->flags))
 169                 printk("tty_write_flush: bit already cleared\n");
 170 }
 171 
 172 void tty_read_flush(struct tty_struct * tty)
     /*  */
 173 {
 174         if (!tty || EMPTY(&tty->read_q))
 175                 return;
 176         if (set_bit(TTY_READ_BUSY, &tty->flags))
 177                 return;
 178         ldiscs[tty->disc].handler(tty);
 179         if (!clear_bit(TTY_READ_BUSY, &tty->flags))
 180                 printk("tty_read_flush: bit already cleared\n");
 181 }
 182 
 183 static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 184 {
 185         return 0;
 186 }
 187 
 188 static int hung_up_tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 189 {
 190         return -EIO;
 191 }
 192 
 193 static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
 194 {
 195         return 1;
 196 }
 197 
 198 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
     /*  */
 199                              unsigned int cmd, unsigned long arg)
 200 {
 201         return -EIO;
 202 }
 203 
 204 static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 205 {
 206         return -ESPIPE;
 207 }
 208 
 209 static struct file_operations tty_fops = {
 210         tty_lseek,
 211         tty_read,
 212         tty_write,
 213         NULL,           /* tty_readdir */
 214         tty_select,
 215         tty_ioctl,
 216         NULL,           /* tty_mmap */
 217         tty_open,
 218         tty_release
 219 };
 220 
 221 static struct file_operations hung_up_tty_fops = {
 222         tty_lseek,
 223         hung_up_tty_read,
 224         hung_up_tty_write,
 225         NULL,           /* hung_up_tty_readdir */
 226         hung_up_tty_select,
 227         tty_ioctl,
 228         NULL,           /* hung_up_tty_mmap */
 229         tty_open,
 230         tty_release
 231 };
 232 
 233 static struct file_operations vhung_up_tty_fops = {
 234         tty_lseek,
 235         hung_up_tty_read,
 236         hung_up_tty_write,
 237         NULL,           /* hung_up_tty_readdir */
 238         hung_up_tty_select,
 239         hung_up_tty_ioctl,
 240         NULL,           /* hung_up_tty_mmap */
 241         tty_open,
 242         tty_release
 243 };
 244 
 245 void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
     /*  */
 246 {
 247         int i;
 248         struct file * filp;
 249         struct task_struct **p;
 250         int dev;
 251 
 252         if (!tty)
 253                 return;
 254         dev = 0x0400 + tty->line;
 255         for (filp = first_file, i=0; i<nr_files; i++, filp = filp->f_next) {
 256                 if (!filp->f_count)
 257                         continue;
 258                 if (filp->f_rdev != dev)
 259                         continue;
 260                 if (filp->f_inode && filp->f_inode->i_rdev == 0x0400)
 261                         continue;
 262                 if (filp->f_op != &tty_fops)
 263                         continue;
 264                 filp->f_op = fops;
 265         }
 266         wake_up_interruptible(&tty->secondary.proc_list);
 267         wake_up_interruptible(&tty->read_q.proc_list);
 268         wake_up_interruptible(&tty->write_q.proc_list);
 269         if (tty->session > 0)
 270                 kill_sl(tty->session,SIGHUP,1);
 271         tty->session = 0;
 272         tty->pgrp = -1;
 273         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
 274                 if ((*p) && (*p)->tty == tty->line)
 275                         (*p)->tty = -1;
 276         }
 277 }
 278 
 279 void tty_hangup(struct tty_struct * tty)
     /*  */
 280 {
 281         do_tty_hangup(tty, &hung_up_tty_fops);
 282 }
 283 
 284 void tty_vhangup(struct tty_struct * tty)
     /*  */
 285 {
 286         do_tty_hangup(tty, &vhung_up_tty_fops);
 287 }
 288 
 289 void tty_unhangup(struct file *filp)
     /*  */
 290 {
 291         filp->f_op = &tty_fops;
 292 }
 293 
 294 int tty_hung_up_p(struct file * filp)
     /*  */
 295 {
 296         return ((filp->f_op == &hung_up_tty_fops) ||
 297                 (filp->f_op == &vhung_up_tty_fops));
 298 }
 299 
 300 /*
 301  * Sometimes we want to wait until a particular VT has been activated. We
 302  * do it in a very simple manner. Everybody waits on a single queue and
 303  * get woken up at once. Those that are satisfied go on with their business,
 304  * while those not ready go back to sleep. Seems overkill to add a wait
 305  * to each vt just for this - usually this does nothing!
 306  */
 307 static struct wait_queue *vt_activate_queue = NULL;
 308 
 309 /*
 310  * Sleeps until a vt is activated, or the task is interrupted. Returns
 311  * 0 if activation, -1 if interrupted.
 312  */
 313 int vt_waitactive(void)
     /*  */
 314 {
 315         interruptible_sleep_on(&vt_activate_queue);
 316         return (current->signal & ~current->blocked) ? -1 : 0;
 317 }
 318 
 319 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 320 
 321 extern int kill_proc(int pid, int sig, int priv);
 322 
 323 /*
 324  * Performs the back end of a vt switch
 325  */
 326 void complete_change_console(unsigned int new_console)
     /*  */
 327 {
 328         unsigned char old_vc_mode;
 329 
 330         if (new_console == fg_console || new_console >= NR_CONSOLES)
 331                 return;
 332 
 333         /*
 334          * If we're switching, we could be going from KD_GRAPHICS to
 335          * KD_TEXT mode or vice versa, which means we need to blank or
 336          * unblank the screen later.
 337          */
 338         old_vc_mode = vt_cons[fg_console].vc_mode;
 339         update_screen(new_console);
 340 
 341         /*
 342          * If this new console is under process control, send it a signal
 343          * telling it that it has acquired. Also check if it has died and
 344          * clean up (similar to logic employed in change_console())
 345          */
 346         if (vt_cons[new_console].vt_mode.mode == VT_PROCESS)
 347         {
 348                 /*
 349                  * Send the signal as privileged - kill_proc() will
 350                  * tell us if the process has gone or something else
 351                  * is awry
 352                  */
 353                 if (kill_proc(vt_cons[new_console].vt_pid,
 354                               vt_cons[new_console].vt_mode.acqsig,
 355                               1) != 0)
 356                 {
 357                 /*
 358                  * The controlling process has died, so we revert back to
 359                  * normal operation. In this case, we'll also change back
 360                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 361                  * but it saves the agony when the X server dies and the screen
 362                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 363                  * this outside of VT_PROCESS but there is no single process
 364                  * to account for and tracking tty count may be undesirable.
 365                  */
 366                         vt_cons[new_console].vc_mode = KD_TEXT;
 367                         clr_vc_kbd_flag(kbd_table + new_console, VC_RAW);
 368                         vt_cons[new_console].vt_mode.mode = VT_AUTO;
 369                         vt_cons[new_console].vt_mode.waitv = 0;
 370                         vt_cons[new_console].vt_mode.relsig = 0;
 371                         vt_cons[new_console].vt_mode.acqsig = 0;
 372                         vt_cons[new_console].vt_mode.frsig = 0;
 373                         vt_cons[new_console].vt_pid = -1;
 374                         vt_cons[new_console].vt_newvt = -1;
 375                 }
 376         }
 377 
 378         /*
 379          * We do this here because the controlling process above may have
 380          * gone, and so there is now a new vc_mode
 381          */
 382         if (old_vc_mode != vt_cons[new_console].vc_mode)
 383         {
 384                 if (vt_cons[new_console].vc_mode == KD_TEXT)
 385                         unblank_screen();
 386                 else {
 387                         timer_active &= ~(1<<BLANK_TIMER);
 388                         blank_screen();
 389                 }
 390         }
 391 
 392         /*
 393          * Wake anyone waiting for their VT to activate
 394          */
 395         vt_wake_waitactive();
 396         return;
 397 }
 398 
 399 /*
 400  * Performs the front-end of a vt switch
 401  */
 402 void change_console(unsigned int new_console)
     /*  */
 403 {
 404         if (new_console == fg_console || new_console >= NR_CONSOLES)
 405                 return;
 406 
 407         /*
 408          * If this vt is in process mode, then we need to handshake with
 409          * that process before switching. Essentially, we store where that
 410          * vt wants to switch to and wait for it to tell us when it's done
 411          * (via VT_RELDISP ioctl).
 412          *
 413          * We also check to see if the controlling process still exists.
 414          * If it doesn't, we reset this vt to auto mode and continue.
 415          * This is a cheap way to track process control. The worst thing
 416          * that can happen is: we send a signal to a process, it dies, and
 417          * the switch gets "lost" waiting for a response; hopefully, the
 418          * user will try again, we'll detect the process is gone (unless
 419          * the user waits just the right amount of time :-) and revert the
 420          * vt to auto control.
 421          */
 422         if (vt_cons[fg_console].vt_mode.mode == VT_PROCESS)
 423         {
 424                 /*
 425                  * Send the signal as privileged - kill_proc() will
 426                  * tell us if the process has gone or something else
 427                  * is awry
 428                  */
 429                 if (kill_proc(vt_cons[fg_console].vt_pid,
 430                               vt_cons[fg_console].vt_mode.relsig,
 431                               1) == 0)
 432                 {
 433                         /*
 434                          * It worked. Mark the vt to switch to and
 435                          * return. The process needs to send us a
 436                          * VT_RELDISP ioctl to complete the switch.
 437                          */
 438                         vt_cons[fg_console].vt_newvt = new_console;
 439                         return;
 440                 }
 441 
 442                 /*
 443                  * The controlling process has died, so we revert back to
 444                  * normal operation. In this case, we'll also change back
 445                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 446                  * but it saves the agony when the X server dies and the screen
 447                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 448                  * this outside of VT_PROCESS but there is no single process
 449                  * to account for and tracking tty count may be undesirable.
 450                  */
 451                 vt_cons[fg_console].vc_mode = KD_TEXT;
 452                 clr_vc_kbd_flag(kbd_table + fg_console, VC_RAW);
 453                 vt_cons[fg_console].vt_mode.mode = VT_AUTO;
 454                 vt_cons[fg_console].vt_mode.waitv = 0;
 455                 vt_cons[fg_console].vt_mode.relsig = 0;
 456                 vt_cons[fg_console].vt_mode.acqsig = 0;
 457                 vt_cons[fg_console].vt_mode.frsig = 0;
 458                 vt_cons[fg_console].vt_pid = -1;
 459                 vt_cons[fg_console].vt_newvt = -1;
 460                 /*
 461                  * Fall through to normal (VT_AUTO) handling of the switch...
 462                  */
 463         }
 464 
 465         /*
 466          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 467          */
 468         if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
 469                 return;
 470 
 471         complete_change_console(new_console);
 472 }
 473 
 474 void wait_for_keypress(void)
     /*  */
 475 {
 476         sleep_on(&keypress_wait);
 477 }
 478 
 479 void copy_to_cooked(struct tty_struct * tty)
     /*  */
 480 {
 481         int c, special_flag;
 482         unsigned long flags;
 483 
 484         if (!tty) {
 485                 printk("copy_to_cooked: called with NULL tty\n");
 486                 return;
 487         }
 488         if (!tty->write) {
 489                 printk("copy_to_cooked: tty %d has null write routine\n",
 490                        tty->line);
 491         }
 492         while (1) {
 493                 /*
 494                  * Check to see how much room we have left in the
 495                  * secondary queue.  Send a throttle command or abort
 496                  * if necessary.
 497                  */
 498                 c = LEFT(&tty->secondary);
 499                 if (tty->throttle && (c < SQ_THRESHOLD_LW)
 500                     && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
 501                         tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
 502                 if (c == 0)
 503                         break;
 504                 save_flags(flags); cli();
 505                 if (tty->read_q.tail != tty->read_q.head) {
 506                         c = 0xff & tty->read_q.buf[tty->read_q.tail];
 507                         special_flag = clear_bit(tty->read_q.tail,
 508                                                   &tty->readq_flags);
 509                         tty->read_q.tail = (tty->read_q.tail + 1) &
 510                                 (TTY_BUF_SIZE-1);
 511                         restore_flags(flags);
 512                 } else {
 513                         restore_flags(flags);
 514                         break;
 515                 }
 516                 if (special_flag) {
 517                         tty->char_error = c & 3;
 518                         continue;
 519                 }
 520                 if (tty->char_error) {
 521                         if (tty->char_error == TTY_BREAK) {
 522                                 tty->char_error = 0;
 523                                 if (I_IGNBRK(tty))
 524                                         continue;
 525                                 if (I_PARMRK(tty)) {
 526                                         put_tty_queue('\377', &tty->secondary);
 527                                         put_tty_queue('\0', &tty->secondary);
 528                                 }
 529                                 put_tty_queue('\0', &tty->secondary);
 530                                 continue;
 531                         }
 532                         /* If not a break, then a parity or frame error */
 533                         tty->char_error = 0;
 534                         if (I_IGNPAR(tty)) {
 535                                 continue;
 536                         }
 537                         if (I_PARMRK(tty)) {
 538                                 put_tty_queue('\377', &tty->secondary);
 539                                 put_tty_queue('\0', &tty->secondary);
 540                                 put_tty_queue(c, &tty->secondary);
 541                         } else
 542                                 put_tty_queue('\0', &tty->secondary);
 543                         continue;
 544                 }
 545                 if (I_STRP(tty))
 546                         c &= 0x7f;
 547                 else if (I_PARMRK(tty) && (c == '\377'))
 548                         put_tty_queue('\377', &tty->secondary);
 549                 if (c==13) {
 550                         if (I_CRNL(tty))
 551                                 c=10;
 552                         else if (I_NOCR(tty))
 553                                 continue;
 554                 } else if (c==10 && I_NLCR(tty))
 555                         c=13;
 556                 if (I_UCLC(tty))
 557                         c=tolower(c);
 558                 if (c == __DISABLED_CHAR)
 559                         tty->lnext = 1;
 560                 if (L_CANON(tty) && !tty->lnext) {
 561                         if (c == KILL_CHAR(tty) || c == WERASE_CHAR(tty)) {
 562                                 int seen_alnums =
 563                                   (c == WERASE_CHAR(tty)) ? 0 : -1;
 564 
 565                                 /* deal with killing the input line */
 566                                 while(!(EMPTY(&tty->secondary) ||
 567                                         (c=LAST(&tty->secondary))==10 ||
 568                                         ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 569                                          (c==EOF_CHAR(tty))))) {
 570                                         /* if killing just a word, kill all
 571                                            non-alnum chars, then all alnum
 572                                            chars.  */
 573                                         if (seen_alnums >= 0) {
 574                                                 if (isalnum(c))
 575                                                         seen_alnums++;
 576                                                 else if (seen_alnums)
 577                                                         break;
 578                                         }
 579                                         if (L_ECHO(tty)) {
 580                                                 if (c<32) {
 581                                                         put_tty_queue('\b', &tty->write_q);
 582                                                         put_tty_queue(' ', &tty->write_q);
 583                                                         put_tty_queue('\b',&tty->write_q);
 584                                                 }
 585                                                 put_tty_queue('\b',&tty->write_q);
 586                                                 put_tty_queue(' ',&tty->write_q);
 587                                                 put_tty_queue('\b',&tty->write_q);
 588                                         }
 589                                         DEC(tty->secondary.head);
 590                                 }
 591                                 continue;
 592                         }
 593                         if (c == ERASE_CHAR(tty)) {
 594                                 if (EMPTY(&tty->secondary) ||
 595                                    (c=LAST(&tty->secondary))==10 ||
 596                                    ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 597                                     (c==EOF_CHAR(tty))))
 598                                         continue;
 599                                 if (L_ECHO(tty)) {
 600                                         if (c<32) {
 601                                                 put_tty_queue('\b',&tty->write_q);
 602                                                 put_tty_queue(' ',&tty->write_q);
 603                                                 put_tty_queue('\b',&tty->write_q);
 604                                         }
 605                                         put_tty_queue('\b',&tty->write_q);
 606                                         put_tty_queue(' ',&tty->write_q);
 607                                         put_tty_queue('\b',&tty->write_q);
 608                                 }
 609                                 DEC(tty->secondary.head);
 610                                 continue;
 611                         }
 612                         if (c == LNEXT_CHAR(tty)) {
 613                                 tty->lnext = 1;
 614                                 if (L_ECHO(tty)) {
 615                                         put_tty_queue('^',&tty->write_q);
 616                                         put_tty_queue('\b',&tty->write_q);
 617                                 }
 618                                 continue;
 619                         }
 620                 }
 621                 if (I_IXON(tty) && !tty->lnext) {
 622                         if (c == STOP_CHAR(tty)) {
 623                                 tty->ctrl_status &= ~(TIOCPKT_START);
 624                                 tty->ctrl_status |= TIOCPKT_STOP;
 625                                 if (tty->link)
 626                                         wake_up_interruptible(&tty->link->except_q);
 627                                 tty->stopped=1;
 628                                 if (tty->stop)
 629                                         (tty->stop)(tty);
 630                                 if (IS_A_CONSOLE(tty->line)) {
 631                                         set_vc_kbd_flag(kbd_table + fg_console, VC_SCROLLOCK);
 632                                         set_leds();
 633                                 }
 634                                 continue;
 635                         }
 636                         if (((I_IXANY(tty)) && tty->stopped) ||
 637                             (c == START_CHAR(tty))) {
 638                                 tty->ctrl_status &= ~(TIOCPKT_STOP);
 639                                 tty->ctrl_status |= TIOCPKT_START;
 640                                 tty->stopped=0;
 641                                 if (tty->link)
 642                                         wake_up_interruptible(&tty->link->except_q);
 643                                 if (tty->start)
 644                                         (tty->start)(tty);
 645                                 if (IS_A_CONSOLE(tty->line)) {
 646                                         clr_vc_kbd_flag(kbd_table + fg_console, VC_SCROLLOCK);
 647                                         set_leds();
 648                                 }
 649                                 continue;
 650                         }
 651                 }
 652                 if (L_ISIG(tty) && !tty->lnext) {
 653                         if (c == INTR_CHAR(tty)) {
 654                                 kill_pg(tty->pgrp, SIGINT, 1);
 655                                 if (! _L_FLAG(tty, NOFLSH)) {
 656                                   flush_input(tty);
 657                                   flush_output(tty);
 658                                 }
 659                                 continue;
 660                         }
 661                         if (c == QUIT_CHAR(tty)) {
 662                                 kill_pg(tty->pgrp, SIGQUIT, 1);
 663                                 if (! _L_FLAG(tty, NOFLSH)) {
 664                                   flush_input(tty);
 665                                   flush_output(tty);
 666                                 }
 667                                 continue;
 668                         }
 669                         if (c == SUSPEND_CHAR(tty)) {
 670                                 if (!is_orphaned_pgrp(tty->pgrp)) {
 671                                         kill_pg(tty->pgrp, SIGTSTP, 1);
 672                                         if (! _L_FLAG(tty, NOFLSH)) {
 673                                           flush_input(tty);
 674                                           flush_output(tty);
 675                                         }
 676                                 }
 677                                 continue;
 678                         }
 679                 }
 680                 if (c==10 || (EOF_CHAR(tty) != __DISABLED_CHAR &&
 681                     c==EOF_CHAR(tty)))
 682                         tty->secondary.data++;
 683                 if ((c==10) && (L_ECHO(tty) || (L_CANON(tty) && L_ECHONL(tty)))) {
 684                         put_tty_queue('\n',&tty->write_q);
 685                         put_tty_queue('\r',&tty->write_q);
 686                 } else if (L_ECHO(tty)) {
 687                         if (c<32 && L_ECHOCTL(tty)) {
 688                                 put_tty_queue('^',&tty->write_q);
 689                                 put_tty_queue(c+'A'-1, &tty->write_q);
 690                                 if (EOF_CHAR(tty) != __DISABLED_CHAR &&
 691                                     c==EOF_CHAR(tty) && !tty->lnext) {
 692                                         put_tty_queue('\b',&tty->write_q);
 693                                         put_tty_queue('\b',&tty->write_q);
 694                                 }
 695                         } else
 696                                 put_tty_queue(c, &tty->write_q);
 697                 }
 698                 tty->lnext = 0;
 699                 put_tty_queue(c, &tty->secondary);
 700         }
 701         TTY_WRITE_FLUSH(tty);
 702         if (!EMPTY(&tty->secondary))
 703                 wake_up_interruptible(&tty->secondary.proc_list);
 704         if (tty->write_q.proc_list && LEFT(&tty->write_q) > TTY_BUF_SIZE/2)
 705                 wake_up_interruptible(&tty->write_q.proc_list);
 706         if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
 707             && clear_bit(TTY_RQ_THROTTLED, &tty->flags))
 708                 tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
 709         if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 710             && clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 711                 tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 712 }
 713 
 714 int is_ignored(int sig)
     /*  */
 715 {
 716         return ((current->blocked & (1<<(sig-1))) ||
 717                 (current->sigaction[sig-1].sa_handler == SIG_IGN));
 718 }
 719 
 720 static int available_canon_input(struct tty_struct *);
 721 static void __wait_for_canon_input(struct file * file, struct tty_struct *);
 722 
 723 static void wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 724 {
 725         if (!available_canon_input(tty)) {
 726                 if (current->signal & ~current->blocked)
 727                         return;
 728                 __wait_for_canon_input(file, tty);
 729         }
 730 }
 731 
 732 static int read_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 733 {
 734         struct wait_queue wait = { current, NULL };
 735         int c;
 736         char * b=buf;
 737         int minimum,time;
 738 
 739         if (L_CANON(tty))
 740                 minimum = time = current->timeout = 0;
 741         else {
 742                 time = 10L*tty->termios->c_cc[VTIME];
 743                 minimum = tty->termios->c_cc[VMIN];
 744                 if (minimum)
 745                         current->timeout = 0xffffffff;
 746                 else {
 747                         if (time)
 748                                 current->timeout = time + jiffies;
 749                         else
 750                                 current->timeout = 0;
 751                         time = 0;
 752                         minimum = 1;
 753                 }
 754         }
 755         if (file->f_flags & O_NONBLOCK) {
 756                 time = current->timeout = 0;
 757                 if (L_CANON(tty) && !available_canon_input(tty))
 758                                 return -EAGAIN;
 759         } else if (L_CANON(tty)) {
 760                 wait_for_canon_input(file, tty);
 761                 if (current->signal & ~current->blocked)
 762                         return -ERESTARTSYS;
 763         }
 764         if (minimum>nr)
 765                 minimum = nr;
 766 
 767         /* deal with packet mode:  First test for status change */
 768         if (tty->packet && tty->link && tty->link->ctrl_status) {
 769                 put_fs_byte (tty->link->ctrl_status, b);
 770                 tty->link->ctrl_status = 0;
 771                 return 1;
 772         }
 773           
 774         /* now bump the buffer up one. */
 775         if (tty->packet) {
 776                 put_fs_byte (0,b++);
 777                 nr--;
 778                 /* this really shouldn't happen, but we need to 
 779                 put it here. */
 780                 if (nr == 0)
 781                         return 1;
 782         }
 783         add_wait_queue(&tty->secondary.proc_list, &wait);
 784         while (nr>0) {
 785                 if (tty_hung_up_p(file)) {
 786                         file->f_flags &= ~O_NONBLOCK;
 787                         break;  /* force read() to return 0 */
 788                 }
 789                 TTY_READ_FLUSH(tty);
 790                 if (tty->link)
 791                         TTY_WRITE_FLUSH(tty->link);
 792                 while (nr > 0 && ((c = get_tty_queue(&tty->secondary)) >= 0)) {
 793                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 794                              c==EOF_CHAR(tty)) || c==10)
 795                                 tty->secondary.data--;
 796                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 797                              c==EOF_CHAR(tty)) && L_CANON(tty))
 798                                 break;
 799                         put_fs_byte(c,b++);
 800                         nr--;
 801                         if (time)
 802                                 current->timeout = time+jiffies;
 803                         if (c==10 && L_CANON(tty))
 804                                 break;
 805                 };
 806                 wake_up_interruptible(&tty->read_q.proc_list);
 807                 /*
 808                  * If there is enough space in the secondary queue
 809                  * now, let the low-level driver know.
 810                  */
 811                 if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 812                     && clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 813                         tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 814                 if (tty->link) {
 815                         if (IS_A_PTY_MASTER(tty->line)) {
 816                                 if ((tty->flags & (1 << TTY_SLAVE_OPENED))
 817                                     && tty->link->count <= 1) {
 818                                         file->f_flags &= ~O_NONBLOCK;
 819                                         break;
 820                                 }
 821                         } else if (!tty->link->count) {
 822                                 file->f_flags &= ~O_NONBLOCK;
 823                                 break;
 824                         }
 825                 }
 826                 if (b-buf >= minimum || !current->timeout)
 827                         break;
 828                 if (current->signal & ~current->blocked) 
 829                         break;
 830                 TTY_READ_FLUSH(tty);
 831                 if (tty->link)
 832                         TTY_WRITE_FLUSH(tty->link);
 833                 if (!EMPTY(&tty->secondary))
 834                         continue;
 835                 current->state = TASK_INTERRUPTIBLE;
 836                 if (EMPTY(&tty->secondary))
 837                         schedule();
 838                 current->state = TASK_RUNNING;
 839         }
 840         remove_wait_queue(&tty->secondary.proc_list, &wait);
 841         TTY_READ_FLUSH(tty);
 842         if (tty->link && tty->link->write)
 843                 TTY_WRITE_FLUSH(tty->link);
 844         current->timeout = 0;
 845 
 846         /* packet mode sticks in an extra 0.  If that's all we've got,
 847            we should count it a zero bytes. */
 848         if (tty->packet) {
 849                 if ((b-buf) > 1)
 850                         return b-buf;
 851         } else {
 852                 if (b-buf)
 853                         return b-buf;
 854         }
 855 
 856         if (current->signal & ~current->blocked)
 857                 return -ERESTARTSYS;
 858         if (file->f_flags & O_NONBLOCK)
 859                 return -EAGAIN;
 860         if (IS_A_PTY_MASTER(tty->line))
 861                 return -EIO;
 862         return 0;
 863 }
 864 
 865 static void __wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 866 {
 867         struct wait_queue wait = { current, NULL };
 868 
 869         add_wait_queue(&tty->secondary.proc_list, &wait);
 870         while (1) {
 871                 current->state = TASK_INTERRUPTIBLE;
 872                 if (available_canon_input(tty))
 873                         break;
 874                 if (current->signal & ~current->blocked)
 875                         break;
 876                 if (tty_hung_up_p(file))
 877                         break;
 878                 schedule();
 879         }
 880         current->state = TASK_RUNNING;
 881         remove_wait_queue(&tty->secondary.proc_list, &wait);
 882 }
 883 
 884 static int available_canon_input(struct tty_struct * tty)
     /*  */
 885 {
 886         TTY_READ_FLUSH(tty);
 887         if (tty->link)
 888                 if (tty->link->count)
 889                         TTY_WRITE_FLUSH(tty->link);
 890                 else
 891                         return 1;
 892         if (FULL(&tty->read_q))
 893                 return 1;
 894         if (tty->secondary.data)
 895                 return 1;
 896         return 0;
 897 }
 898 
 899 static int write_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 900 {
 901         struct wait_queue wait = { current, NULL };
 902         char c, *b=buf;
 903 
 904         if (nr < 0)
 905                 return -EINVAL;
 906         if (!nr)
 907                 return 0;
 908         add_wait_queue(&tty->write_q.proc_list, &wait);
 909         while (nr>0) {
 910                 if (current->signal & ~current->blocked)
 911                         break;
 912                 if (tty_hung_up_p(file))
 913                         break;
 914                 if (tty->link && !tty->link->count) {
 915                         send_sig(SIGPIPE,current,0);
 916                         break;
 917                 }
 918                 current->state = TASK_INTERRUPTIBLE;
 919                 if (FULL(&tty->write_q)) {
 920                         TTY_WRITE_FLUSH(tty);
 921                         if (FULL(&tty->write_q))
 922                                 schedule();
 923                         current->state = TASK_RUNNING;
 924                         continue;
 925                 }
 926                 current->state = TASK_RUNNING;
 927                 while (nr>0 && !FULL(&tty->write_q)) {
 928                         c=get_fs_byte(b);
 929                         if (O_POST(tty)) {
 930                                 switch (c) {
 931                                         case '\n':
 932                                                 if (O_NLRET(tty)) {
 933                                                         tty->column = 0;
 934                                                 }
 935                                                 if (O_NLCR(tty)) {
 936                                                         if (!set_bit(TTY_CR_PENDING,&tty->flags)) {
 937                                                                 c = '\r';
 938                                                                 tty->column = 0;
 939                                                                 b--; nr++;
 940                                                         } else {
 941                                                                 clear_bit(TTY_CR_PENDING,&tty->flags);
 942                                                         }
 943                                                 }
 944                                                 break;
 945                                         case '\r':
 946                                                 if (O_NOCR(tty) && tty->column == 0) {
 947                                                         b++; nr--;
 948                                                         continue;
 949                                                 }
 950                                                 if (O_CRNL(tty)) {
 951                                                         c = '\n';
 952                                                         if (O_NLRET(tty))
 953                                                                 tty->column = 0;
 954                                                         break;
 955                                                 }
 956                                                 tty->column = 0;
 957                                                 break;
 958                                         case '\t':
 959                                                 if (O_TABDLY(tty) == XTABS) {
 960                                                         c = ' ';
 961                                                         tty->column++;
 962                                                         if (tty->column % 8 != 0) {
 963                                                                 b--; nr++;
 964                                                         }
 965                                                 }
 966                                                 break;
 967                                         case '\b':
 968                                                 tty->column--;
 969                                                 break;
 970                                         default:
 971                                                 if (O_LCUC(tty))
 972                                                         c = toupper(c);
 973                                                 tty->column++;
 974                                                 break;
 975                                 }
 976                         }
 977                         b++; nr--;
 978                         put_tty_queue(c,&tty->write_q);
 979                 }
 980                 if (need_resched)
 981                         schedule();
 982         }
 983         remove_wait_queue(&tty->write_q.proc_list, &wait);
 984         TTY_WRITE_FLUSH(tty);
 985         if (b-buf)
 986                 return b-buf;
 987         if (tty->link && !tty->link->count)
 988                 return -EPIPE;
 989         if (current->signal & ~current->blocked)
 990                 return -ERESTARTSYS;
 991         return 0;
 992 }
 993 
 994 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 995 {
 996         int i, dev;
 997         struct tty_struct * tty;
 998 
 999         dev = file->f_rdev;
1000         if (MAJOR(dev) != TTY_MAJOR) {
1001                 printk("tty_read: bad pseudo-major nr #%d\n", MAJOR(dev));
1002                 return -EINVAL;
1003         }
1004         dev = MINOR(dev);
1005         tty = TTY_TABLE(dev);
1006         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
1007                 return -EIO;
1008         if ((inode->i_rdev != 0x0400) && /* don't stop on /dev/console */
1009             (tty->pgrp > 0) &&
1010             (current->tty == dev) &&
1011             (tty->pgrp != current->pgrp))
1012                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
1013                         return -EIO;
1014                 else {
1015                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
1016                         return -ERESTARTSYS;
1017                 }
1018         if (ldiscs[tty->disc].read)
1019                 i = (ldiscs[tty->disc].read)(tty,file,buf,count);
1020         else
1021                 i = -EIO;
1022         if (i > 0)
1023                 inode->i_atime = CURRENT_TIME;
1024         return i;
1025 }
1026 
1027 static int tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
1028 {
1029         int dev, i, is_console;
1030         struct tty_struct * tty;
1031 
1032         dev = file->f_rdev;
1033         is_console = (inode->i_rdev == 0x0400);
1034         if (MAJOR(dev) != TTY_MAJOR) {
1035                 printk("tty_write: pseudo-major != TTY_MAJOR\n");
1036                 return -EINVAL;
1037         }
1038         dev = MINOR(dev);
1039         if (is_console && redirect)
1040                 tty = redirect;
1041         else
1042                 tty = TTY_TABLE(dev);
1043         if (!tty || !tty->write || (tty->flags & (1 << TTY_IO_ERROR)))
1044                 return -EIO;
1045         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
1046             (current->tty == dev) && (tty->pgrp != current->pgrp)) {
1047                 if (is_orphaned_pgrp(current->pgrp))
1048                         return -EIO;
1049                 if (!is_ignored(SIGTTOU)) {
1050                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
1051                         return -ERESTARTSYS;
1052                 }
1053         }
1054         if (ldiscs[tty->disc].write)
1055                 i = (ldiscs[tty->disc].write)(tty,file,buf,count);
1056         else
1057                 i = -EIO;
1058         if (i > 0)
1059                 inode->i_mtime = CURRENT_TIME;
1060         return i;
1061 }
1062 
1063 /*
1064  * This is so ripe with races that you should *really* not touch this
1065  * unless you know exactly what you are doing. All the changes have to be
1066  * made atomically, or there may be incorrect pointers all over the place.
1067  */
1068 static int init_dev(int dev)
     /*  */
1069 {
1070         struct tty_struct *tty, *o_tty;
1071         struct termios *tp, *o_tp, *ltp, *o_ltp;
1072         int retval;
1073         int o_dev;
1074 
1075         o_dev = PTY_OTHER(dev);
1076         tty = o_tty = NULL;
1077         tp = o_tp = NULL;
1078         ltp = o_ltp = NULL;
1079 repeat:
1080         retval = -EAGAIN;
1081         if (IS_A_PTY_MASTER(dev) && tty_table[dev] && tty_table[dev]->count)
1082                 goto end_init;
1083         retval = -ENOMEM;
1084         if (!tty_table[dev] && !tty) {
1085                 if (!(tty = (struct tty_struct*) get_free_page(GFP_KERNEL)))
1086                         goto end_init;
1087                 initialize_tty_struct(dev, tty);
1088                 goto repeat;
1089         }
1090         if (!tty_termios[dev] && !tp) {
1091                 tp = (struct termios *) kmalloc(sizeof(struct termios),
1092                                                 GFP_KERNEL);
1093                 if (!tp)
1094                         goto end_init;
1095                 initialize_termios(dev, tp);
1096                 goto repeat;
1097         }
1098         if (!termios_locked[dev] && !ltp) {
1099                 ltp = (struct termios *) kmalloc(sizeof(struct termios),
1100                                                  GFP_KERNEL);
1101                 if (!ltp)
1102                         goto end_init;
1103                 memset(ltp, 0, sizeof(struct termios));
1104                 goto repeat;
1105         }
1106         if (IS_A_PTY(dev)) {
1107                 if (!tty_table[o_dev] && !o_tty) {
1108                         o_tty = (struct tty_struct *)
1109                                 get_free_page(GFP_KERNEL);
1110                         if (!o_tty)
1111                                 goto end_init;
1112                         initialize_tty_struct(o_dev, o_tty);
1113                         goto repeat;
1114                 }
1115                 if (!tty_termios[o_dev] && !o_tp) {
1116                         o_tp = (struct termios *)
1117                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
1118                         if (!o_tp)
1119                                 goto end_init;
1120                         initialize_termios(o_dev, o_tp);
1121                         goto repeat;
1122                 }
1123                 if (!termios_locked[o_dev] && !o_ltp) {
1124                         o_ltp = (struct termios *)
1125                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
1126                         if (!o_ltp)
1127                                 goto end_init;
1128                         memset(o_ltp, 0, sizeof(struct termios));
1129                         goto repeat;
1130                 }
1131                 
1132         }
1133         /* Now we have allocated all the structures: update all the pointers.. */
1134         if (!tty_termios[dev]) {
1135                 tty_termios[dev] = tp;
1136                 tp = NULL;
1137         }
1138         if (!tty_table[dev]) {
1139                 tty->termios = tty_termios[dev];
1140                 tty_table[dev] = tty;
1141                 tty = NULL;
1142         }
1143         if (!termios_locked[dev]) {
1144                 termios_locked[dev] = ltp;
1145                 ltp = NULL;
1146         }
1147         if (IS_A_PTY(dev)) {
1148                 if (!tty_termios[o_dev]) {
1149                         tty_termios[o_dev] = o_tp;
1150                         o_tp = NULL;
1151                 }
1152                 if (!termios_locked[o_dev]) {
1153                         termios_locked[o_dev] = o_ltp;
1154                         o_ltp = NULL;
1155                 }
1156                 if (!tty_table[o_dev]) {
1157                         o_tty->termios = tty_termios[o_dev];
1158                         tty_table[o_dev] = o_tty;
1159                         o_tty = NULL;
1160                 }
1161                 tty_table[dev]->link = tty_table[o_dev];
1162                 tty_table[o_dev]->link = tty_table[dev];
1163         }
1164         tty_table[dev]->count++;
1165         if (IS_A_PTY_MASTER(dev))
1166                 tty_table[o_dev]->count++;
1167         retval = 0;
1168 end_init:
1169         if (tty)
1170                 free_page((unsigned long) tty);
1171         if (o_tty)
1172                 free_page((unsigned long) o_tty);
1173         if (tp)
1174                 kfree_s(tp, sizeof(struct termios));
1175         if (o_tp)
1176                 kfree_s(o_tp, sizeof(struct termios));
1177         if (ltp)
1178                 kfree_s(ltp, sizeof(struct termios));
1179         if (o_ltp)
1180                 kfree_s(o_ltp, sizeof(struct termios));
1181         return retval;
1182 }
1183 
1184 /*
1185  * Even releasing the tty structures is a tricky business.. We have
1186  * to be very careful that the structures are all released at the
1187  * same time, as interrupts might otherwise get the wrong pointers.
1188  */
1189 static void release_dev(int dev, struct file * filp)
     /*  */
1190 {
1191         struct tty_struct *tty, *o_tty;
1192         struct termios *tp, *o_tp;
1193         struct task_struct **p;
1194 
1195         tty = tty_table[dev];
1196         tp = tty_termios[dev];
1197         o_tty = NULL;
1198         o_tp = NULL;
1199         if (!tty) {
1200                 printk("release_dev: tty_table[%d] was NULL\n", dev);
1201                 return;
1202         }
1203         if (!tp) {
1204                 printk("release_dev: tty_termios[%d] was NULL\n", dev);
1205                 return;
1206         }
1207         if (IS_A_PTY(dev)) {
1208                 o_tty = tty_table[PTY_OTHER(dev)];
1209                 o_tp = tty_termios[PTY_OTHER(dev)];
1210                 if (!o_tty) {
1211                         printk("release_dev: pty pair(%d) was NULL\n", dev);
1212                         return;
1213                 }
1214                 if (!o_tp) {
1215                         printk("release_dev: pty pair(%d) termios was NULL\n", dev);
1216                         return;
1217                 }
1218                 if (tty->link != o_tty || o_tty->link != tty) {
1219                         printk("release_dev: bad pty pointers\n");
1220                         return;
1221                 }
1222         }
1223         tty->write_data_cnt = 0; /* Clear out pending trash */
1224         if (tty->close)
1225                 tty->close(tty, filp);
1226         if (IS_A_PTY_MASTER(dev)) {
1227                 if (--tty->link->count < 0) {
1228                         printk("release_dev: bad tty slave count (dev = %d): %d\n",
1229                                dev, tty->count);
1230                         tty->link->count = 0;
1231                 }
1232         }
1233         if (--tty->count < 0) {
1234                 printk("release_dev: bad tty_table[%d]->count: %d\n",
1235                        dev, tty->count);
1236                 tty->count = 0;
1237         }
1238         if (tty->count)
1239                 return;
1240 
1241         /*
1242          * Make sure there aren't any processes that still think this
1243          * tty is their controlling tty.
1244          */
1245         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1246                 if ((*p) && (*p)->tty == tty->line)
1247                 (*p)->tty = -1;
1248         }
1249 
1250         if (ldiscs[tty->disc].close != NULL)
1251                 ldiscs[tty->disc].close(tty);
1252 
1253         if (o_tty) {
1254                 if (o_tty->count)
1255                         return;
1256                 else {
1257                         tty_table[PTY_OTHER(dev)] = NULL;
1258                         tty_termios[PTY_OTHER(dev)] = NULL;
1259                 }
1260         }
1261         tty_table[dev] = NULL;
1262         if (IS_A_PTY(dev)) {
1263                 tty_termios[dev] = NULL;
1264                 kfree_s(tp, sizeof(struct termios));
1265         }
1266         if (tty == redirect || o_tty == redirect)
1267                 redirect = NULL;
1268         free_page((unsigned long) tty);
1269         if (o_tty)
1270                 free_page((unsigned long) o_tty);
1271         if (o_tp)
1272                 kfree_s(o_tp, sizeof(struct termios));
1273 }
1274 
1275 /*
1276  * tty_open and tty_release keep up the tty count that contains the
1277  * number of opens done on a tty. We cannot use the inode-count, as
1278  * different inodes might point to the same tty.
1279  *
1280  * Open-counting is needed for pty masters, as well as for keeping
1281  * track of serial lines: DTR is dropped when the last close happens.
1282  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1283  *
1284  * The termios state of a pty is reset on first open so that
1285  * settings don't persist across reuse.
1286  */
1287 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1288 {
1289         struct tty_struct *tty;
1290         int major, minor;
1291         int noctty, retval;
1292 
1293         minor = MINOR(inode->i_rdev);
1294         major = MAJOR(inode->i_rdev);
1295         noctty = filp->f_flags & O_NOCTTY;
1296         if (major == TTYAUX_MAJOR) {
1297                 if (!minor) {
1298                         major = TTY_MAJOR;
1299                         minor = current->tty;
1300                 }
1301                 noctty = 1;
1302         } else if (major == TTY_MAJOR) {
1303                 if (!minor) {
1304                         minor = fg_console + 1;
1305                         noctty = 1;
1306                 }
1307         } else {
1308                 printk("Bad major #%d in tty_open\n", MAJOR(inode->i_rdev));
1309                 return -ENODEV;
1310         }
1311         if (minor <= 0)
1312                 return -ENXIO;
1313         if (IS_A_PTY_MASTER(minor))
1314                 noctty = 1;
1315         filp->f_rdev = (major << 8) | minor;
1316         retval = init_dev(minor);
1317         if (retval)
1318                 return retval;
1319         tty = tty_table[minor];
1320 
1321         /* clean up the packet stuff. */
1322         /*
1323          *  Why is this not done in init_dev?  Right here, if another 
1324          * process opens up a tty in packet mode, all the packet 
1325          * variables get cleared.  Come to think of it, is anything 
1326          * using the packet mode at all???  - Ted, 1/27/93
1327          *
1328          * Not to worry, a pty master can only be opened once.
1329          * And rlogind and telnetd both use packet mode.  -- jrs
1330          */
1331         tty->ctrl_status = 0;
1332         tty->packet = 0;
1333 
1334         if (tty->open) {
1335                 retval = tty->open(tty, filp);
1336         } else {
1337                 retval = -ENODEV;
1338         }
1339         if (retval) {
1340                 release_dev(minor, filp);
1341                 return retval;
1342         }
1343         if (!noctty &&
1344             current->leader &&
1345             current->tty<0 &&
1346             tty->session==0) {
1347                 current->tty = minor;
1348                 tty->session = current->session;
1349                 tty->pgrp = current->pgrp;
1350         }
1351         filp->f_rdev = 0x0400 | minor; /* Set it to something normal */
1352         return 0;
1353 }
1354 
1355 /*
1356  * Note that releasing a pty master also releases the child, so
1357  * we have to make the redirection checks after that and on both
1358  * sides of a pty.
1359  */
1360 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1361 {
1362         int dev;
1363 
1364         dev = filp->f_rdev;
1365         if (MAJOR(dev) != TTY_MAJOR) {
1366                 printk("tty_release: tty pseudo-major != TTY_MAJOR\n");
1367                 return;
1368         }
1369         dev = MINOR(filp->f_rdev);
1370         if (!dev) {
1371                 printk("tty_release: bad f_rdev\n");
1372                 return;
1373         }
1374         release_dev(dev, filp);
1375 }
1376 
1377 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1378 {
1379         int dev;
1380         struct tty_struct * tty;
1381 
1382         dev = filp->f_rdev;
1383         if (MAJOR(dev) != TTY_MAJOR) {
1384                 printk("tty_select: tty pseudo-major != TTY_MAJOR\n");
1385                 return 0;
1386         }
1387         dev = MINOR(filp->f_rdev);
1388         tty = TTY_TABLE(dev);
1389         if (!tty) {
1390                 printk("tty_select: tty struct for dev %d was NULL\n", dev);
1391                 return 0;
1392         }
1393         switch (sel_type) {
1394                 case SEL_IN:
1395                         if (L_CANON(tty)) {
1396                                 if (available_canon_input(tty))
1397                                         return 1;
1398                         } else if (!EMPTY(&tty->secondary))
1399                                 return 1;
1400                         if (tty->link) {
1401                                 if (IS_A_PTY_MASTER(tty->line)) {
1402                                         if ((tty->flags & (1 << TTY_SLAVE_OPENED))
1403                                             && tty->link->count <= 1)
1404                                                 return 1;
1405                                 } else {
1406                                         if (!tty->link->count)
1407                                                 return 1;
1408                                 }
1409                         }
1410 
1411                         /* see if the status byte can be read. */
1412                         if (tty->packet && tty->link && tty->link->ctrl_status)
1413                                 return 1;
1414 
1415                         select_wait(&tty->secondary.proc_list, wait);
1416                         return 0;
1417                 case SEL_OUT:
1418                         if (!FULL(&tty->write_q))
1419                                 return 1;
1420                         select_wait(&tty->write_q.proc_list, wait);
1421                         return 0;
1422                 case SEL_EX:
1423                         if (tty->link) {
1424                                 if (IS_A_PTY_MASTER(tty->line)) {
1425                                         if ((tty->flags & (1 << TTY_SLAVE_OPENED))
1426                                             && tty->link->count <= 1)
1427                                                 return 1;
1428                                         if (tty->packet
1429                                             && tty->link->ctrl_status)
1430                                                 return 1;
1431                                 } else {
1432                                         if (!tty->link->count)
1433                                                 return 1;
1434                                 }
1435                         }
1436                         select_wait(&tty->except_q, wait);
1437                         return 0;
1438         }
1439         return 0;
1440 }
1441 
1442 /*
1443  * This implements the "Secure Attention Key" ---  the idea is to
1444  * prevent trojan horses by killing all processes associated with this
1445  * tty when the user hits the "Secure Attention Key".  Required for
1446  * super-paranoid applications --- see the Orange Book for more details.
1447  * 
1448  * This code could be nicer; ideally it should send a HUP, wait a few
1449  * seconds, then send a INT, and then a KILL signal.  But you then
1450  * have to coordinate with the init process, since all processes associated
1451  * with the current tty must be dead before the new getty is allowed
1452  * to spawn.
1453  */
1454 void do_SAK( struct tty_struct *tty)
     /*  */
1455 {
1456         struct task_struct **p;
1457         int line = tty->line;
1458         int session = tty->session;
1459         int             i;
1460         struct file     *filp;
1461         
1462         flush_input(tty);
1463         flush_output(tty);
1464         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1465                 if (!(*p))
1466                         continue;
1467                 if (((*p)->tty == line) ||
1468                     ((session > 0) && ((*p)->session == session)))
1469                         send_sig(SIGKILL, *p, 1);
1470                 else {
1471                         for (i=0; i < NR_OPEN; i++) {
1472                                 filp = (*p)->filp[i];
1473                                 if (filp && (filp->f_op == &tty_fops) &&
1474                                     (MINOR(filp->f_rdev) == line)) {
1475                                         send_sig(SIGKILL, *p, 1);
1476                                         break;
1477                                 }
1478                         }
1479                 }
1480         }
1481 }
1482 
1483 /*
1484  * This routine allows a kernel routine to send a large chunk of data
1485  * to a particular tty; if all of the data can be queued up for ouput
1486  * immediately, tty_write_data() will return 0.  If, however, not all
1487  * of the data can be immediately queued for delivery, the number of
1488  * bytes left to be queued up will be returned, and the rest of the
1489  * data will be queued up when there is room.  The callback function
1490  * will be called (with the argument callarg) when the last of the
1491  * data is finally in the queue.
1492  *
1493  * Note that the callback routine will _not_ be called if all of the
1494  * data could be queued immediately.  This is to avoid a problem with
1495  * the kernel stack getting too deep, which might happen if the
1496  * callback routine calls tty_write_data with itself as an argument.
1497  */
1498 int tty_write_data(struct tty_struct *tty, char *bufp, int buflen,
     /*  */
1499                     void (*callback)(void * data), void * callarg)
1500 {
1501         int head, tail, count;
1502         unsigned long flags;
1503         char *p;
1504 
1505 #define VLEFT ((tail-head-1)&(TTY_BUF_SIZE-1))
1506 
1507         save_flags(flags);
1508         cli();
1509         if (tty->write_data_cnt) {
1510                 restore_flags(flags);
1511                 return -EBUSY;
1512         }
1513 
1514         head = tty->write_q.head;
1515         tail = tty->write_q.tail;
1516         count = buflen;
1517         p = bufp;
1518 
1519         while (count && VLEFT > 0) {
1520                 tty->write_q.buf[head++] = *p++;
1521                 head &= TTY_BUF_SIZE-1;
1522                 count--;
1523         }
1524         tty->write_q.head = head;
1525         if (count) {
1526                 tty->write_data_cnt = count;
1527                 tty->write_data_ptr = (unsigned char *) p;
1528                 tty->write_data_callback = callback;
1529                 tty->write_data_arg = callarg;
1530         }
1531         restore_flags(flags);
1532         tty->write(tty);
1533         return count;
1534 }
1535 
1536 /*
1537  * This routine routine is called after an interrupt has drained a
1538  * tty's write queue, so that there is more space for data waiting to
1539  * be sent in tty->write_data_ptr.
1540  *
1541  * tty_check_write[8] is a bitstring which indicates which ttys
1542  * needs to be processed.
1543  */
1544 void tty_bh_routine(void * unused)
     /*  */
1545 {
1546         int     i, j, line, mask;
1547         int     head, tail, count;
1548         unsigned char * p;
1549         struct tty_struct * tty;
1550 
1551         for (i = 0, line = 0; i < MAX_TTYS / 32; i++) {
1552                 if (!tty_check_write[i]) {
1553                         line += 32;
1554                         continue;
1555                 }
1556                 for (j=0, mask=0; j < 32; j++, line++, mask <<= 1) {
1557                         if (clear_bit(j, &tty_check_write[i])) {
1558                                 tty = tty_table[line];
1559                                 if (!tty || !tty->write_data_cnt)
1560                                         continue;
1561                                 cli();
1562                                 head = tty->write_q.head;
1563                                 tail = tty->write_q.tail;
1564                                 count = tty->write_data_cnt;
1565                                 p = tty->write_data_ptr;
1566 
1567                                 while (count && VLEFT > 0) {
1568                                         tty->write_q.buf[head++] = *p++;
1569                                         head &= TTY_BUF_SIZE-1;
1570                                         count--;
1571                                 }
1572                                 tty->write_q.head = head;
1573                                 tty->write_data_ptr = p;
1574                                 tty->write_data_cnt = count;
1575                                 sti();
1576                                 if (!count)
1577                                         (tty->write_data_callback)
1578                                                 (tty->write_data_arg);
1579                         }
1580                 }
1581         }
1582         
1583 }
1584 
1585 /*
1586  * This subroutine initializes a tty structure.  We have to set up
1587  * things correctly for each different type of tty.
1588  */
1589 static void initialize_tty_struct(int line, struct tty_struct *tty)
     /*  */
1590 {
1591         memset(tty, 0, sizeof(struct tty_struct));
1592         tty->line = line;
1593         tty->disc = N_TTY;
1594         tty->pgrp = -1;
1595         tty->winsize.ws_row = 0;
1596         tty->winsize.ws_col = 0;
1597         if (IS_A_CONSOLE(line)) {
1598                 tty->open = con_open;
1599                 tty->winsize.ws_row = video_num_lines;
1600                 tty->winsize.ws_col = video_num_columns;
1601         } else if IS_A_SERIAL(line) {
1602                 tty->open = rs_open;
1603         } else if IS_A_PTY(line) {
1604                 tty->open = pty_open;
1605         }
1606         tty->except_q = NULL;
1607 }
1608 
1609 static void initialize_termios(int line, struct termios * tp)
     /*  */
1610 {
1611         memset(tp, 0, sizeof(struct termios));
1612         memcpy(tp->c_cc, INIT_C_CC, NCCS);
1613         if (IS_A_CONSOLE(line)) {
1614                 tp->c_iflag = ICRNL | IXON;
1615                 tp->c_oflag = OPOST | ONLCR;
1616                 tp->c_cflag = B38400 | CS8 | CREAD;
1617                 tp->c_lflag = ISIG | ICANON | ECHO |
1618                         ECHOCTL | ECHOKE;
1619         } else if (IS_A_SERIAL(line)) {
1620                 tp->c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1621                 tp->c_oflag = OPOST | ONLCR | XTABS;
1622         } else if (IS_A_PTY_MASTER(line)) {
1623                 tp->c_cflag = B9600 | CS8 | CREAD;
1624         } else if (IS_A_PTY_SLAVE(line)) {
1625                 tp->c_iflag = ICRNL | IXON;
1626                 tp->c_oflag = OPOST | ONLCR;
1627                 tp->c_cflag = B38400 | CS8 | CREAD;
1628                 tp->c_lflag = ISIG | ICANON | ECHO |
1629                         ECHOCTL | ECHOKE;
1630         }
1631 }
1632 
1633 static struct tty_ldisc tty_ldisc_N_TTY = {
1634         0,                      /* flags */
1635         NULL,                   /* open */
1636         NULL,                   /* close */
1637         read_chan,              /* read */
1638         write_chan,             /* write */
1639         NULL,                   /* ioctl */
1640         copy_to_cooked          /* handler */
1641 };
1642 
1643         
1644 long tty_init(long kmem_start)
     /*  */
1645 {
1646         int i;
1647 
1648         if (sizeof(struct tty_struct) > PAGE_SIZE)
1649                 panic("size of tty structure > PAGE_SIZE!");
1650         if (register_chrdev(TTY_MAJOR,"tty",&tty_fops))
1651                 panic("unable to get major %d for tty device", TTY_MAJOR);
1652         if (register_chrdev(TTYAUX_MAJOR,"tty",&tty_fops))
1653                 panic("unable to get major %d for tty device", TTYAUX_MAJOR);
1654         for (i=0 ; i< MAX_TTYS ; i++) {
1655                 tty_table[i] =  0;
1656                 tty_termios[i] = 0;
1657         }
1658         memset(tty_check_write, 0, sizeof(tty_check_write));
1659         bh_base[TTY_BH].routine = tty_bh_routine;
1660 
1661         /* Setup the default TTY line discipline. */
1662         memset(ldiscs, 0, sizeof(ldiscs));
1663         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1664 
1665         kmem_start = kbd_init(kmem_start);
1666         kmem_start = con_init(kmem_start);
1667         kmem_start = rs_init(kmem_start);
1668         return kmem_start;
1669 }
/* */
root/drivers/char/tty_io.c

DEFINITIONS
