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 tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
  62 int tty_check_write[MAX_TTYS/32];       /* bitfield for the bh handler */
  63 
  64 /*
  65  * fg_console is the current virtual console,
  66  * redirect is the pseudo-tty that console output
  67  * is redirected to if asked by TIOCCONS.
  68  */
  69 int fg_console = 0;
  70 struct tty_struct * redirect = NULL;
  71 struct wait_queue * keypress_wait = NULL;
  72 
  73 static void initialize_tty_struct(int line, struct tty_struct *tty);
  74 static void initialize_termios(int line, struct termios *tp);
  75 
  76 static int tty_read(struct inode *, struct file *, char *, int);
  77 static int tty_write(struct inode *, struct file *, char *, int);
  78 static int tty_select(struct inode *, struct file *, int, select_table *);
  79 static int tty_open(struct inode *, struct file *);
  80 static void tty_release(struct inode *, struct file *);
  81 
  82 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
     /*  */
  83 {
  84         if (disc < N_TTY || disc >= NR_LDISCS)
  85                 return -EINVAL;
  86         
  87         if (new_ldisc) {
  88                 ldiscs[disc] = *new_ldisc;
  89                 ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
  90         } else
  91                 memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
  92         
  93         return 0;
  94 }
  95 
  96 void put_tty_queue(char c, struct tty_queue * queue)
     /*  */
  97 {
  98         int head;
  99         unsigned long flags;
 100 
 101         save_flags(flags);
 102         cli();
 103         head = (queue->head + 1) & (TTY_BUF_SIZE-1);
 104         if (head != queue->tail) {
 105                 queue->buf[queue->head] = c;
 106                 queue->head = head;
 107         }
 108         restore_flags(flags);
 109 }
 110 
 111 int get_tty_queue(struct tty_queue * queue)
     /*  */
 112 {
 113         int result = -1;
 114         unsigned long flags;
 115 
 116         save_flags(flags);
 117         cli();
 118         if (queue->tail != queue->head) {
 119                 result = 0xff & queue->buf[queue->tail];
 120                 queue->tail = (queue->tail + 1) & (TTY_BUF_SIZE-1);
 121         }
 122         restore_flags(flags);
 123         return result;
 124 }
 125 
 126 /*
 127  * This routine copies out a maximum of buflen characters from the
 128  * read_q; it is a convenience for line disciplins so they can grab a
 129  * large block of data without calling get_tty_char directly.  It
 130  * returns the number of characters actually read.
 131  */
 132 int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp, int buflen)
     /*  */
 133 {
 134         int     result = 0;
 135         unsigned char   *p = bufp;
 136         unsigned long flags;
 137         int head, tail;
 138 
 139         save_flags(flags);
 140         cli();
 141         tail = tty->read_q.tail;
 142         head = tty->read_q.head;
 143         while ((result < buflen) && (tail!=head)) {
 144                 *p++ =  tty->read_q.buf[tail++];
 145                 tail &= TTY_BUF_SIZE-1;
 146                 result++;
 147         }
 148         tty->read_q.tail = tail;
 149         restore_flags(flags);
 150         return result;
 151 }
 152 
 153 
 154 void tty_write_flush(struct tty_struct * tty)
     /*  */
 155 {
 156         if (!tty->write || EMPTY(&tty->write_q))
 157                 return;
 158         if (set_bit(TTY_WRITE_BUSY,&tty->flags))
 159                 return;
 160         tty->write(tty);
 161         if (!clear_bit(TTY_WRITE_BUSY,&tty->flags))
 162                 printk("tty_write_flush: bit already cleared\n");
 163 }
 164 
 165 void tty_read_flush(struct tty_struct * tty)
     /*  */
 166 {
 167         if (!tty || EMPTY(&tty->read_q))
 168                 return;
 169         if (set_bit(TTY_READ_BUSY, &tty->flags))
 170                 return;
 171         ldiscs[tty->disc].handler(tty);
 172         if (!clear_bit(TTY_READ_BUSY, &tty->flags))
 173                 printk("tty_read_flush: bit already cleared\n");
 174 }
 175 
 176 static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 177 {
 178         return 0;
 179 }
 180 
 181 static int hung_up_tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 182 {
 183         return -EIO;
 184 }
 185 
 186 static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
 187 {
 188         return 1;
 189 }
 190 
 191 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
     /*  */
 192                              unsigned int cmd, unsigned long arg)
 193 {
 194         return -EIO;
 195 }
 196 
 197 static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 198 {
 199         return -ESPIPE;
 200 }
 201 
 202 static struct file_operations tty_fops = {
 203         tty_lseek,
 204         tty_read,
 205         tty_write,
 206         NULL,           /* tty_readdir */
 207         tty_select,
 208         tty_ioctl,
 209         NULL,           /* tty_mmap */
 210         tty_open,
 211         tty_release
 212 };
 213 
 214 static struct file_operations hung_up_tty_fops = {
 215         tty_lseek,
 216         hung_up_tty_read,
 217         hung_up_tty_write,
 218         NULL,           /* hung_up_tty_readdir */
 219         hung_up_tty_select,
 220         tty_ioctl,
 221         NULL,           /* hung_up_tty_mmap */
 222         tty_open,
 223         tty_release
 224 };
 225 
 226 static struct file_operations vhung_up_tty_fops = {
 227         tty_lseek,
 228         hung_up_tty_read,
 229         hung_up_tty_write,
 230         NULL,           /* hung_up_tty_readdir */
 231         hung_up_tty_select,
 232         hung_up_tty_ioctl,
 233         NULL,           /* hung_up_tty_mmap */
 234         tty_open,
 235         tty_release
 236 };
 237 
 238 void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
     /*  */
 239 {
 240         int i;
 241         struct file * filp;
 242         struct task_struct **p;
 243         int dev;
 244 
 245         if (!tty)
 246                 return;
 247         dev = 0x0400 + tty->line;
 248         for (filp = first_file, i=0; i<nr_files; i++, filp = filp->f_next) {
 249                 if (!filp->f_count)
 250                         continue;
 251                 if (filp->f_rdev != dev)
 252                         continue;
 253                 if (filp->f_inode && filp->f_inode->i_rdev == 0x0400)
 254                         continue;
 255                 if (filp->f_op != &tty_fops)
 256                         continue;
 257                 filp->f_op = fops;
 258         }
 259         wake_up_interruptible(&tty->secondary.proc_list);
 260         wake_up_interruptible(&tty->read_q.proc_list);
 261         wake_up_interruptible(&tty->write_q.proc_list);
 262         if (tty->session > 0)
 263                 kill_sl(tty->session,SIGHUP,1);
 264         tty->session = 0;
 265         tty->pgrp = -1;
 266         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
 267                 if ((*p) && (*p)->tty == tty->line)
 268                         (*p)->tty = -1;
 269         }
 270 }
 271 
 272 void tty_hangup(struct tty_struct * tty)
     /*  */
 273 {
 274         do_tty_hangup(tty, &hung_up_tty_fops);
 275 }
 276 
 277 void tty_vhangup(struct tty_struct * tty)
     /*  */
 278 {
 279         do_tty_hangup(tty, &vhung_up_tty_fops);
 280 }
 281 
 282 void tty_unhangup(struct file *filp)
     /*  */
 283 {
 284         filp->f_op = &tty_fops;
 285 }
 286 
 287 int tty_hung_up_p(struct file * filp)
     /*  */
 288 {
 289         return ((filp->f_op == &hung_up_tty_fops) ||
 290                 (filp->f_op == &vhung_up_tty_fops));
 291 }
 292 
 293 /*
 294  * Sometimes we want to wait until a particular VT has been activated. We
 295  * do it in a very simple manner. Everybody waits on a single queue and
 296  * get woken up at once. Those that are satisfied go on with their business,
 297  * while those not ready go back to sleep. Seems overkill to add a wait
 298  * to each vt just for this - usually this does nothing!
 299  */
 300 static struct wait_queue *vt_activate_queue = NULL;
 301 
 302 /*
 303  * Sleeps until a vt is activated, or the task is interrupted. Returns
 304  * 0 if activation, -1 if interrupted.
 305  */
 306 int vt_waitactive(void)
     /*  */
 307 {
 308         interruptible_sleep_on(&vt_activate_queue);
 309         return (current->signal & ~current->blocked) ? -1 : 0;
 310 }
 311 
 312 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 313 
 314 extern int kill_proc(int pid, int sig, int priv);
 315 
 316 /*
 317  * Performs the back end of a vt switch
 318  */
 319 void complete_change_console(unsigned int new_console)
     /*  */
 320 {
 321         unsigned char old_vc_mode;
 322 
 323         if (new_console == fg_console || new_console >= NR_CONSOLES)
 324                 return;
 325 
 326         /*
 327          * If we're switching, we could be going from KD_GRAPHICS to
 328          * KD_TEXT mode or vice versa, which means we need to blank or
 329          * unblank the screen later.
 330          */
 331         old_vc_mode = vt_cons[fg_console].vc_mode;
 332         update_screen(new_console);
 333 
 334         /*
 335          * If this new console is under process control, send it a signal
 336          * telling it that it has acquired. Also check if it has died and
 337          * clean up (similar to logic employed in change_console())
 338          */
 339         if (vt_cons[new_console].vt_mode.mode == VT_PROCESS)
 340         {
 341                 /*
 342                  * Send the signal as privileged - kill_proc() will
 343                  * tell us if the process has gone or something else
 344                  * is awry
 345                  */
 346                 if (kill_proc(vt_cons[new_console].vt_pid,
 347                               vt_cons[new_console].vt_mode.acqsig,
 348                               1) != 0)
 349                 {
 350                 /*
 351                  * The controlling process has died, so we revert back to
 352                  * normal operation. In this case, we'll also change back
 353                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 354                  * but it saves the agony when the X server dies and the screen
 355                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 356                  * this outside of VT_PROCESS but there is no single process
 357                  * to account for and tracking tty count may be undesirable.
 358                  */
 359                         vt_cons[new_console].vc_mode = KD_TEXT;
 360                         clr_vc_kbd_flag(kbd_table + new_console, VC_RAW);
 361                         vt_cons[new_console].vt_mode.mode = VT_AUTO;
 362                         vt_cons[new_console].vt_mode.waitv = 0;
 363                         vt_cons[new_console].vt_mode.relsig = 0;
 364                         vt_cons[new_console].vt_mode.acqsig = 0;
 365                         vt_cons[new_console].vt_mode.frsig = 0;
 366                         vt_cons[new_console].vt_pid = -1;
 367                         vt_cons[new_console].vt_newvt = -1;
 368                 }
 369         }
 370 
 371         /*
 372          * We do this here because the controlling process above may have
 373          * gone, and so there is now a new vc_mode
 374          */
 375         if (old_vc_mode != vt_cons[new_console].vc_mode)
 376         {
 377                 if (vt_cons[new_console].vc_mode == KD_TEXT)
 378                         unblank_screen();
 379                 else {
 380                         timer_active &= ~(1<<BLANK_TIMER);
 381                         blank_screen();
 382                 }
 383         }
 384 
 385         /*
 386          * Wake anyone waiting for their VT to activate
 387          */
 388         vt_wake_waitactive();
 389         return;
 390 }
 391 
 392 /*
 393  * Performs the front-end of a vt switch
 394  */
 395 void change_console(unsigned int new_console)
     /*  */
 396 {
 397         if (new_console == fg_console || new_console >= NR_CONSOLES)
 398                 return;
 399 
 400         /*
 401          * If this vt is in process mode, then we need to handshake with
 402          * that process before switching. Essentially, we store where that
 403          * vt wants to switch to and wait for it to tell us when it's done
 404          * (via VT_RELDISP ioctl).
 405          *
 406          * We also check to see if the controlling process still exists.
 407          * If it doesn't, we reset this vt to auto mode and continue.
 408          * This is a cheap way to track process control. The worst thing
 409          * that can happen is: we send a signal to a process, it dies, and
 410          * the switch gets "lost" waiting for a response; hopefully, the
 411          * user will try again, we'll detect the process is gone (unless
 412          * the user waits just the right amount of time :-) and revert the
 413          * vt to auto control.
 414          */
 415         if (vt_cons[fg_console].vt_mode.mode == VT_PROCESS)
 416         {
 417                 /*
 418                  * Send the signal as privileged - kill_proc() will
 419                  * tell us if the process has gone or something else
 420                  * is awry
 421                  */
 422                 if (kill_proc(vt_cons[fg_console].vt_pid,
 423                               vt_cons[fg_console].vt_mode.relsig,
 424                               1) == 0)
 425                 {
 426                         /*
 427                          * It worked. Mark the vt to switch to and
 428                          * return. The process needs to send us a
 429                          * VT_RELDISP ioctl to complete the switch.
 430                          */
 431                         vt_cons[fg_console].vt_newvt = new_console;
 432                         return;
 433                 }
 434 
 435                 /*
 436                  * The controlling process has died, so we revert back to
 437                  * normal operation. In this case, we'll also change back
 438                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 439                  * but it saves the agony when the X server dies and the screen
 440                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 441                  * this outside of VT_PROCESS but there is no single process
 442                  * to account for and tracking tty count may be undesirable.
 443                  */
 444                 vt_cons[fg_console].vc_mode = KD_TEXT;
 445                 clr_vc_kbd_flag(kbd_table + fg_console, VC_RAW);
 446                 vt_cons[fg_console].vt_mode.mode = VT_AUTO;
 447                 vt_cons[fg_console].vt_mode.waitv = 0;
 448                 vt_cons[fg_console].vt_mode.relsig = 0;
 449                 vt_cons[fg_console].vt_mode.acqsig = 0;
 450                 vt_cons[fg_console].vt_mode.frsig = 0;
 451                 vt_cons[fg_console].vt_pid = -1;
 452                 vt_cons[fg_console].vt_newvt = -1;
 453                 /*
 454                  * Fall through to normal (VT_AUTO) handling of the switch...
 455                  */
 456         }
 457 
 458         /*
 459          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 460          */
 461         if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
 462                 return;
 463 
 464         complete_change_console(new_console);
 465 }
 466 
 467 void wait_for_keypress(void)
     /*  */
 468 {
 469         sleep_on(&keypress_wait);
 470 }
 471 
 472 void copy_to_cooked(struct tty_struct * tty)
     /*  */
 473 {
 474         int c, special_flag;
 475         unsigned long flags;
 476 
 477         if (!tty) {
 478                 printk("copy_to_cooked: called with NULL tty\n");
 479                 return;
 480         }
 481         if (!tty->write) {
 482                 printk("copy_to_cooked: tty %d has null write routine\n",
 483                        tty->line);
 484         }
 485         while (1) {
 486                 /*
 487                  * Check to see how much room we have left in the
 488                  * secondary queue.  Send a throttle command or abort
 489                  * if necessary.
 490                  */
 491                 c = LEFT(&tty->secondary);
 492                 if (tty->throttle && (c < SQ_THRESHOLD_LW)
 493                     && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
 494                         tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
 495                 if (c == 0)
 496                         break;
 497                 save_flags(flags); cli();
 498                 if (tty->read_q.tail != tty->read_q.head) {
 499                         c = 0xff & tty->read_q.buf[tty->read_q.tail];
 500                         special_flag = clear_bit(tty->read_q.tail,
 501                                                   &tty->readq_flags);
 502                         tty->read_q.tail = (tty->read_q.tail + 1) &
 503                                 (TTY_BUF_SIZE-1);
 504                         restore_flags(flags);
 505                 } else {
 506                         restore_flags(flags);
 507                         break;
 508                 }
 509                 if (special_flag) {
 510                         tty->char_error = c & 3;
 511                         continue;
 512                 }
 513                 if (tty->char_error) {
 514                         if (tty->char_error == TTY_BREAK) {
 515                                 tty->char_error = 0;
 516                                 if (I_IGNBRK(tty))
 517                                         continue;
 518                                 if (I_PARMRK(tty)) {
 519                                         put_tty_queue('\377', &tty->secondary);
 520                                         put_tty_queue('\0', &tty->secondary);
 521                                 }
 522                                 put_tty_queue('\0', &tty->secondary);
 523                                 continue;
 524                         }
 525                         /* If not a break, then a parity or frame error */
 526                         tty->char_error = 0;
 527                         if (I_IGNPAR(tty)) {
 528                                 continue;
 529                         }
 530                         if (I_PARMRK(tty)) {
 531                                 put_tty_queue('\377', &tty->secondary);
 532                                 put_tty_queue('\0', &tty->secondary);
 533                                 put_tty_queue(c, &tty->secondary);
 534                         } else
 535                                 put_tty_queue('\0', &tty->secondary);
 536                         continue;
 537                 }
 538                 if (I_STRP(tty))
 539                         c &= 0x7f;
 540                 else if (I_PARMRK(tty) && (c == '\377'))
 541                         put_tty_queue('\377', &tty->secondary);
 542                 if (c==13) {
 543                         if (I_CRNL(tty))
 544                                 c=10;
 545                         else if (I_NOCR(tty))
 546                                 continue;
 547                 } else if (c==10 && I_NLCR(tty))
 548                         c=13;
 549                 if (I_UCLC(tty))
 550                         c=tolower(c);
 551                 if (c == __DISABLED_CHAR)
 552                         tty->lnext = 1;
 553                 if (L_CANON(tty) && !tty->lnext) {
 554                         if (c == KILL_CHAR(tty) || c == WERASE_CHAR(tty)) {
 555                                 int seen_alnums =
 556                                   (c == WERASE_CHAR(tty)) ? 0 : -1;
 557 
 558                                 /* deal with killing the input line */
 559                                 while(!(EMPTY(&tty->secondary) ||
 560                                         (c=LAST(&tty->secondary))==10 ||
 561                                         ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 562                                          (c==EOF_CHAR(tty))))) {
 563                                         /* if killing just a word, kill all
 564                                            non-alnum chars, then all alnum
 565                                            chars.  */
 566                                         if (seen_alnums >= 0) {
 567                                                 if (isalnum(c))
 568                                                         seen_alnums++;
 569                                                 else if (seen_alnums)
 570                                                         break;
 571                                         }
 572                                         if (L_ECHO(tty)) {
 573                                                 if (c<32) {
 574                                                         put_tty_queue('\b', &tty->write_q);
 575                                                         put_tty_queue(' ', &tty->write_q);
 576                                                         put_tty_queue('\b',&tty->write_q);
 577                                                 }
 578                                                 put_tty_queue('\b',&tty->write_q);
 579                                                 put_tty_queue(' ',&tty->write_q);
 580                                                 put_tty_queue('\b',&tty->write_q);
 581                                         }
 582                                         DEC(tty->secondary.head);
 583                                 }
 584                                 continue;
 585                         }
 586                         if (c == ERASE_CHAR(tty)) {
 587                                 if (EMPTY(&tty->secondary) ||
 588                                    (c=LAST(&tty->secondary))==10 ||
 589                                    ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 590                                     (c==EOF_CHAR(tty))))
 591                                         continue;
 592                                 if (L_ECHO(tty)) {
 593                                         if (c<32) {
 594                                                 put_tty_queue('\b',&tty->write_q);
 595                                                 put_tty_queue(' ',&tty->write_q);
 596                                                 put_tty_queue('\b',&tty->write_q);
 597                                         }
 598                                         put_tty_queue('\b',&tty->write_q);
 599                                         put_tty_queue(' ',&tty->write_q);
 600                                         put_tty_queue('\b',&tty->write_q);
 601                                 }
 602                                 DEC(tty->secondary.head);
 603                                 continue;
 604                         }
 605                         if (c == LNEXT_CHAR(tty)) {
 606                                 tty->lnext = 1;
 607                                 if (L_ECHO(tty)) {
 608                                         put_tty_queue('^',&tty->write_q);
 609                                         put_tty_queue('\b',&tty->write_q);
 610                                 }
 611                                 continue;
 612                         }
 613                 }
 614                 if (I_IXON(tty) && !tty->lnext) {
 615                         if (c == STOP_CHAR(tty)) {
 616                                 tty->status_changed = 1;
 617                                 tty->ctrl_status |= TIOCPKT_STOP;
 618                                 tty->stopped=1;
 619                                 if (IS_A_CONSOLE(tty->line)) {
 620                                         set_vc_kbd_flag(kbd_table + fg_console, VC_SCROLLOCK);
 621                                         set_leds();
 622                                 }
 623                                 continue;
 624                         }
 625                         if (((I_IXANY(tty)) && tty->stopped) ||
 626                             (c == START_CHAR(tty))) {
 627                                 tty->status_changed = 1;
 628                                 tty->ctrl_status |= TIOCPKT_START;
 629                                 tty->stopped=0;
 630                                 if (IS_A_CONSOLE(tty->line)) {
 631                                         clr_vc_kbd_flag(kbd_table + fg_console, VC_SCROLLOCK);
 632                                         set_leds();
 633                                 }
 634                                 continue;
 635                         }
 636                 }
 637                 if (L_ISIG(tty) && !tty->lnext) {
 638                         if (c == INTR_CHAR(tty)) {
 639                                 kill_pg(tty->pgrp, SIGINT, 1);
 640                                 flush_input(tty);
 641                                 continue;
 642                         }
 643                         if (c == QUIT_CHAR(tty)) {
 644                                 kill_pg(tty->pgrp, SIGQUIT, 1);
 645                                 flush_input(tty);
 646                                 continue;
 647                         }
 648                         if (c == SUSPEND_CHAR(tty)) {
 649                                 if (!is_orphaned_pgrp(tty->pgrp)) {
 650                                         kill_pg(tty->pgrp, SIGTSTP, 1);
 651                                         flush_input(tty);
 652                                 }
 653                                 continue;
 654                         }
 655                 }
 656                 if (c==10 || (EOF_CHAR(tty) != __DISABLED_CHAR &&
 657                     c==EOF_CHAR(tty)))
 658                         tty->secondary.data++;
 659                 if ((c==10) && (L_ECHO(tty) || (L_CANON(tty) && L_ECHONL(tty)))) {
 660                         put_tty_queue('\n',&tty->write_q);
 661                         put_tty_queue('\r',&tty->write_q);
 662                 } else if (L_ECHO(tty)) {
 663                         if (c<32 && L_ECHOCTL(tty)) {
 664                                 put_tty_queue('^',&tty->write_q);
 665                                 put_tty_queue(c+'A'-1, &tty->write_q);
 666                                 if (EOF_CHAR(tty) != __DISABLED_CHAR &&
 667                                     c==EOF_CHAR(tty) && !tty->lnext) {
 668                                         put_tty_queue('\b',&tty->write_q);
 669                                         put_tty_queue('\b',&tty->write_q);
 670                                 }
 671                         } else
 672                                 put_tty_queue(c, &tty->write_q);
 673                 }
 674                 tty->lnext = 0;
 675                 put_tty_queue(c, &tty->secondary);
 676         }
 677         TTY_WRITE_FLUSH(tty);
 678         if (!EMPTY(&tty->secondary))
 679                 wake_up_interruptible(&tty->secondary.proc_list);
 680         if (tty->write_q.proc_list && LEFT(&tty->write_q) > TTY_BUF_SIZE/2)
 681                 wake_up_interruptible(&tty->write_q.proc_list);
 682         if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
 683             && clear_bit(TTY_RQ_THROTTLED, &tty->flags))
 684                 tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
 685         if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 686             && clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 687                 tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 688 }
 689 
 690 int is_ignored(int sig)
     /*  */
 691 {
 692         return ((current->blocked & (1<<(sig-1))) ||
 693                 (current->sigaction[sig-1].sa_handler == SIG_IGN));
 694 }
 695 
 696 static int available_canon_input(struct tty_struct *);
 697 static void __wait_for_canon_input(struct file * file, struct tty_struct *);
 698 
 699 static void wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 700 {
 701         if (!available_canon_input(tty)) {
 702                 if (current->signal & ~current->blocked)
 703                         return;
 704                 __wait_for_canon_input(file, tty);
 705         }
 706 }
 707 
 708 static int read_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 709 {
 710         struct wait_queue wait = { current, NULL };
 711         int c;
 712         char * b=buf;
 713         int minimum,time;
 714 
 715         if (L_CANON(tty))
 716                 minimum = time = current->timeout = 0;
 717         else {
 718                 time = 10L*tty->termios->c_cc[VTIME];
 719                 minimum = tty->termios->c_cc[VMIN];
 720                 if (minimum)
 721                         current->timeout = 0xffffffff;
 722                 else {
 723                         if (time)
 724                                 current->timeout = time + jiffies;
 725                         else
 726                                 current->timeout = 0;
 727                         time = 0;
 728                         minimum = 1;
 729                 }
 730         }
 731         if (file->f_flags & O_NONBLOCK) {
 732                 time = current->timeout = 0;
 733                 if (L_CANON(tty) && !available_canon_input(tty))
 734                                 return -EAGAIN;
 735         } else if (L_CANON(tty)) {
 736                 wait_for_canon_input(file, tty);
 737                 if (current->signal & ~current->blocked)
 738                         return -ERESTARTSYS;
 739         }
 740         if (minimum>nr)
 741                 minimum = nr;
 742 
 743         /* deal with packet mode:  First test for status change */
 744         if (tty->packet && tty->link && tty->link->status_changed) {
 745                 put_fs_byte (tty->link->ctrl_status, b);
 746                 tty->link->status_changed = 0;
 747                 return 1;
 748         }
 749           
 750         /* now bump the buffer up one. */
 751         if (tty->packet) {
 752                 put_fs_byte (0,b++);
 753                 nr--;
 754                 /* this really shouldn't happen, but we need to 
 755                 put it here. */
 756                 if (nr == 0)
 757                         return 1;
 758         }
 759         add_wait_queue(&tty->secondary.proc_list, &wait);
 760         while (nr>0) {
 761                 if (tty_hung_up_p(file)) {
 762                         file->f_flags &= ~O_NONBLOCK;
 763                         break;  /* force read() to return 0 */
 764                 }
 765                 TTY_READ_FLUSH(tty);
 766                 if (tty->link)
 767                         TTY_WRITE_FLUSH(tty->link);
 768                 while (nr > 0 && ((c = get_tty_queue(&tty->secondary)) >= 0)) {
 769                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 770                              c==EOF_CHAR(tty)) || c==10)
 771                                 tty->secondary.data--;
 772                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 773                              c==EOF_CHAR(tty)) && L_CANON(tty))
 774                                 break;
 775                         put_fs_byte(c,b++);
 776                         nr--;
 777                         if (time)
 778                                 current->timeout = time+jiffies;
 779                         if (c==10 && L_CANON(tty))
 780                                 break;
 781                 };
 782                 wake_up_interruptible(&tty->read_q.proc_list);
 783                 /*
 784                  * If there is enough space in the secondary queue
 785                  * now, let the low-level driver know.
 786                  */
 787                 if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 788                     && clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 789                         tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 790                 if (b-buf >= minimum || !current->timeout)
 791                         break;
 792                 if (current->signal & ~current->blocked) 
 793                         break;
 794                 if (tty->link) {
 795                         if (IS_A_PTY_MASTER(tty->line)) {
 796                                 if ((tty->flags & (1 << TTY_SLAVE_OPENED))
 797                                     && tty->link->count <= 1)
 798                                         break;
 799                         } else {
 800                                 if (!tty->link->count)
 801                                         break;
 802                         }
 803                 }
 804                 TTY_READ_FLUSH(tty);
 805                 if (tty->link)
 806                         TTY_WRITE_FLUSH(tty->link);
 807                 if (!EMPTY(&tty->secondary))
 808                         continue;
 809                 current->state = TASK_INTERRUPTIBLE;
 810                 if (EMPTY(&tty->secondary))
 811                         schedule();
 812                 current->state = TASK_RUNNING;
 813         }
 814         remove_wait_queue(&tty->secondary.proc_list, &wait);
 815         TTY_READ_FLUSH(tty);
 816         if (tty->link && tty->link->write)
 817                 TTY_WRITE_FLUSH(tty->link);
 818         current->timeout = 0;
 819 
 820         /* packet mode sticks in an extra 0.  If that's all we've got,
 821            we should count it a zero bytes. */
 822         if (tty->packet) {
 823                 if ((b-buf) > 1)
 824                         return b-buf;
 825         } else {
 826                 if (b-buf)
 827                         return b-buf;
 828         }
 829 
 830         if (current->signal & ~current->blocked)
 831                 return -ERESTARTSYS;
 832         if (file->f_flags & O_NONBLOCK)
 833                 return -EAGAIN;
 834         if (IS_A_PTY_MASTER(tty->line))
 835                 return -EIO;
 836         return 0;
 837 }
 838 
 839 static void __wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 840 {
 841         struct wait_queue wait = { current, NULL };
 842 
 843         add_wait_queue(&tty->secondary.proc_list, &wait);
 844         while (1) {
 845                 current->state = TASK_INTERRUPTIBLE;
 846                 if (available_canon_input(tty))
 847                         break;
 848                 if (current->signal & ~current->blocked)
 849                         break;
 850                 if (tty_hung_up_p(file))
 851                         break;
 852                 schedule();
 853         }
 854         current->state = TASK_RUNNING;
 855         remove_wait_queue(&tty->secondary.proc_list, &wait);
 856 }
 857 
 858 static int available_canon_input(struct tty_struct * tty)
     /*  */
 859 {
 860         TTY_READ_FLUSH(tty);
 861         if (tty->link)
 862                 if (tty->link->count)
 863                         TTY_WRITE_FLUSH(tty->link);
 864                 else
 865                         return 1;
 866         if (FULL(&tty->read_q))
 867                 return 1;
 868         if (tty->secondary.data)
 869                 return 1;
 870         return 0;
 871 }
 872 
 873 static int write_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 874 {
 875         struct wait_queue wait = { current, NULL };
 876         char c, *b=buf;
 877 
 878         if (nr < 0)
 879                 return -EINVAL;
 880         if (!nr)
 881                 return 0;
 882         add_wait_queue(&tty->write_q.proc_list, &wait);
 883         while (nr>0) {
 884                 if (current->signal & ~current->blocked)
 885                         break;
 886                 if (tty_hung_up_p(file))
 887                         break;
 888                 if (tty->link && !tty->link->count) {
 889                         send_sig(SIGPIPE,current,0);
 890                         break;
 891                 }
 892                 current->state = TASK_INTERRUPTIBLE;
 893                 if (FULL(&tty->write_q)) {
 894                         TTY_WRITE_FLUSH(tty);
 895                         if (FULL(&tty->write_q))
 896                                 schedule();
 897                         current->state = TASK_RUNNING;
 898                         continue;
 899                 }
 900                 current->state = TASK_RUNNING;
 901                 while (nr>0 && !FULL(&tty->write_q)) {
 902                         c=get_fs_byte(b);
 903                         if (O_POST(tty)) {
 904                                 switch (c) {
 905                                         case '\n':
 906                                                 if (O_NLRET(tty)) {
 907                                                         tty->column = 0;
 908                                                 }
 909                                                 if (O_NLCR(tty)) {
 910                                                         if (!set_bit(TTY_CR_PENDING,&tty->flags)) {
 911                                                                 c = '\r';
 912                                                                 tty->column = 0;
 913                                                                 b--; nr++;
 914                                                         } else {
 915                                                                 clear_bit(TTY_CR_PENDING,&tty->flags);
 916                                                         }
 917                                                 }
 918                                                 break;
 919                                         case '\r':
 920                                                 if (O_NOCR(tty) && tty->column == 0) {
 921                                                         b++; nr--;
 922                                                         continue;
 923                                                 }
 924                                                 if (O_CRNL(tty)) {
 925                                                         c = '\n';
 926                                                         if (O_NLRET(tty))
 927                                                                 tty->column = 0;
 928                                                         break;
 929                                                 }
 930                                                 tty->column = 0;
 931                                                 break;
 932                                         case '\t':
 933                                                 if (O_TABDLY(tty) == XTABS) {
 934                                                         c = ' ';
 935                                                         tty->column++;
 936                                                         if (tty->column % 8 != 0) {
 937                                                                 b--; nr++;
 938                                                         }
 939                                                 }
 940                                                 break;
 941                                         case '\b':
 942                                                 tty->column--;
 943                                                 break;
 944                                         default:
 945                                                 if (O_LCUC(tty))
 946                                                         c = toupper(c);
 947                                                 tty->column++;
 948                                                 break;
 949                                 }
 950                         }
 951                         b++; nr--;
 952                         put_tty_queue(c,&tty->write_q);
 953                 }
 954                 if (need_resched)
 955                         schedule();
 956         }
 957         remove_wait_queue(&tty->write_q.proc_list, &wait);
 958         TTY_WRITE_FLUSH(tty);
 959         if (b-buf)
 960                 return b-buf;
 961         if (tty->link && !tty->link->count)
 962                 return -EPIPE;
 963         if (current->signal & ~current->blocked)
 964                 return -ERESTARTSYS;
 965         return 0;
 966 }
 967 
 968 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 969 {
 970         int i, dev;
 971         struct tty_struct * tty;
 972 
 973         dev = file->f_rdev;
 974         if (MAJOR(dev) != 4) {
 975                 printk("tty_read: bad pseudo-major nr #%d\n", MAJOR(dev));
 976                 return -EINVAL;
 977         }
 978         dev = MINOR(dev);
 979         tty = TTY_TABLE(dev);
 980         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 981                 return -EIO;
 982         if ((inode->i_rdev != 0x0400) && /* don't stop on /dev/console */
 983             (tty->pgrp > 0) &&
 984             (current->tty == dev) &&
 985             (tty->pgrp != current->pgrp))
 986                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 987                         return -EIO;
 988                 else {
 989                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 990                         return -ERESTARTSYS;
 991                 }
 992         if (ldiscs[tty->disc].read)
 993                 i = (ldiscs[tty->disc].read)(tty,file,buf,count);
 994         else
 995                 i = -EIO;
 996         if (i > 0)
 997                 inode->i_atime = CURRENT_TIME;
 998         return i;
 999 }
1000 
1001 static int tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
1002 {
1003         int dev, i, is_console;
1004         struct tty_struct * tty;
1005 
1006         dev = file->f_rdev;
1007         is_console = (inode->i_rdev == 0x0400);
1008         if (MAJOR(dev) != 4) {
1009                 printk("tty_write: pseudo-major != 4\n");
1010                 return -EINVAL;
1011         }
1012         dev = MINOR(dev);
1013         if (is_console && redirect)
1014                 tty = redirect;
1015         else
1016                 tty = TTY_TABLE(dev);
1017         if (!tty || !tty->write || (tty->flags & (1 << TTY_IO_ERROR)))
1018                 return -EIO;
1019         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
1020             (current->tty == dev) && (tty->pgrp != current->pgrp)) {
1021                 if (is_orphaned_pgrp(current->pgrp))
1022                         return -EIO;
1023                 if (!is_ignored(SIGTTOU)) {
1024                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
1025                         return -ERESTARTSYS;
1026                 }
1027         }
1028         if (ldiscs[tty->disc].write)
1029                 i = (ldiscs[tty->disc].write)(tty,file,buf,count);
1030         else
1031                 i = -EIO;
1032         if (i > 0)
1033                 inode->i_mtime = CURRENT_TIME;
1034         return i;
1035 }
1036 
1037 /*
1038  * This is so ripe with races that you should *really* not touch this
1039  * unless you know exactly what you are doing. All the changes have to be
1040  * made atomically, or there may be incorrect pointers all over the place.
1041  */
1042 static int init_dev(int dev)
     /*  */
1043 {
1044         struct tty_struct *tty, *o_tty;
1045         struct termios *tp, *o_tp;
1046         int retval;
1047         int o_dev;
1048 
1049         o_dev = PTY_OTHER(dev);
1050         tty = o_tty = NULL;
1051         tp = o_tp = NULL;
1052 repeat:
1053         retval = -EAGAIN;
1054         if (IS_A_PTY_MASTER(dev) && tty_table[dev] && tty_table[dev]->count)
1055                 goto end_init;
1056         retval = -ENOMEM;
1057         if (!tty_table[dev] && !tty) {
1058                 tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
1059                 if (!tty)
1060                         goto end_init;
1061                 initialize_tty_struct(dev, tty);
1062                 goto repeat;
1063         }
1064         if (!tty_termios[dev] && !tp) {
1065                 tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
1066                 if (!tp)
1067                         goto end_init;
1068                 initialize_termios(dev, tp);
1069                 goto repeat;
1070         }
1071         if (IS_A_PTY(dev)) {
1072                 if (!tty_table[o_dev] && !o_tty) {
1073                         o_tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
1074                         if (!o_tty)
1075                                 goto end_init;
1076                         initialize_tty_struct(o_dev, o_tty);
1077                         goto repeat;
1078                 }
1079                 if (!tty_termios[o_dev] && !o_tp) {
1080                         o_tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
1081                         if (!o_tp)
1082                                 goto end_init;
1083                         initialize_termios(o_dev, o_tp);
1084                         goto repeat;
1085                 }
1086         }
1087         /* Now we have allocated all the structures: update all the pointers.. */
1088         if (!tty_termios[dev]) {
1089                 tty_termios[dev] = tp;
1090                 tp = NULL;
1091         }
1092         if (!tty_table[dev]) {
1093                 tty->termios = tty_termios[dev];
1094                 tty_table[dev] = tty;
1095                 tty = NULL;
1096         }
1097         if (IS_A_PTY(dev)) {
1098                 if (!tty_termios[o_dev]) {
1099                         tty_termios[o_dev] = o_tp;
1100                         o_tp = NULL;
1101                 }
1102                 if (!tty_table[o_dev]) {
1103                         o_tty->termios = tty_termios[o_dev];
1104                         tty_table[o_dev] = o_tty;
1105                         o_tty = NULL;
1106                 }
1107                 tty_table[dev]->link = tty_table[o_dev];
1108                 tty_table[o_dev]->link = tty_table[dev];
1109         }
1110         tty_table[dev]->count++;
1111         if (IS_A_PTY_MASTER(dev))
1112                 tty_table[o_dev]->count++;
1113         retval = 0;
1114 end_init:
1115         if (tty)
1116                 free_page((unsigned long) tty);
1117         if (o_tty)
1118                 free_page((unsigned long) o_tty);
1119         if (tp)
1120                 kfree_s(tp, sizeof(struct termios));
1121         if (o_tp)
1122                 kfree_s(o_tp, sizeof(struct termios));
1123         return retval;
1124 }
1125 
1126 /*
1127  * Even releasing the tty structures is a tricky business.. We have
1128  * to be very careful that the structures are all released at the
1129  * same time, as interrupts might otherwise get the wrong pointers.
1130  */
1131 static void release_dev(int dev, struct file * filp)
     /*  */
1132 {
1133         struct tty_struct *tty, *o_tty;
1134         struct termios *tp, *o_tp;
1135         struct task_struct **p;
1136 
1137         tty = tty_table[dev];
1138         tp = tty_termios[dev];
1139         o_tty = NULL;
1140         o_tp = NULL;
1141         if (!tty) {
1142                 printk("release_dev: tty_table[%d] was NULL\n", dev);
1143                 return;
1144         }
1145         if (!tp) {
1146                 printk("release_dev: tty_termios[%d] was NULL\n", dev);
1147                 return;
1148         }
1149         if (IS_A_PTY(dev)) {
1150                 o_tty = tty_table[PTY_OTHER(dev)];
1151                 o_tp = tty_termios[PTY_OTHER(dev)];
1152                 if (!o_tty) {
1153                         printk("release_dev: pty pair(%d) was NULL\n", dev);
1154                         return;
1155                 }
1156                 if (!o_tp) {
1157                         printk("release_dev: pty pair(%d) termios was NULL\n", dev);
1158                         return;
1159                 }
1160                 if (tty->link != o_tty || o_tty->link != tty) {
1161                         printk("release_dev: bad pty pointers\n");
1162                         return;
1163                 }
1164         }
1165         tty->write_data_cnt = 0; /* Clear out pending trash */
1166         if (tty->close)
1167                 tty->close(tty, filp);
1168         if (IS_A_PTY_MASTER(dev)) {
1169                 if (--tty->link->count < 0) {
1170                         printk("release_dev: bad tty slave count (dev = %d): %d\n",
1171                                dev, tty->count);
1172                         tty->link->count = 0;
1173                 }
1174         }
1175         if (--tty->count < 0) {
1176                 printk("release_dev: bad tty_table[%d]->count: %d\n",
1177                        dev, tty->count);
1178                 tty->count = 0;
1179         }
1180         if (tty->count)
1181                 return;
1182 
1183         /*
1184          * Make sure there aren't any processes that still think this
1185          * tty is their controlling tty.
1186          */
1187         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1188                 if ((*p) && (*p)->tty == tty->line)
1189                 (*p)->tty = -1;
1190         }
1191 
1192         if (ldiscs[tty->disc].close != NULL)
1193                 ldiscs[tty->disc].close(tty);
1194 
1195         if (o_tty) {
1196                 if (o_tty->count)
1197                         return;
1198                 else {
1199                         tty_table[PTY_OTHER(dev)] = NULL;
1200                         tty_termios[PTY_OTHER(dev)] = NULL;
1201                 }
1202         }
1203         tty_table[dev] = NULL;
1204         if (IS_A_PTY(dev)) {
1205                 tty_termios[dev] = NULL;
1206                 kfree_s(tp, sizeof(struct termios));
1207         }
1208         if (tty == redirect || o_tty == redirect)
1209                 redirect = NULL;
1210         free_page((unsigned long) tty);
1211         if (o_tty)
1212                 free_page((unsigned long) o_tty);
1213         if (o_tp)
1214                 kfree_s(o_tp, sizeof(struct termios));
1215 }
1216 
1217 /*
1218  * tty_open and tty_release keep up the tty count that contains the
1219  * number of opens done on a tty. We cannot use the inode-count, as
1220  * different inodes might point to the same tty.
1221  *
1222  * Open-counting is needed for pty masters, as well as for keeping
1223  * track of serial lines: DTR is dropped when the last close happens.
1224  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1225  *
1226  * The termios state of a pty is reset on first open so that
1227  * settings don't persist across reuse.
1228  */
1229 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1230 {
1231         struct tty_struct *tty;
1232         int major, minor;
1233         int noctty, retval;
1234 
1235         minor = MINOR(inode->i_rdev);
1236         major = MAJOR(inode->i_rdev);
1237         noctty = filp->f_flags & O_NOCTTY;
1238         if (major == 5) {
1239                 if (!minor) {
1240                         major = 4;
1241                         minor = current->tty;
1242                 }
1243                 noctty = 1;
1244         } else if (major == 4) {
1245                 if (!minor) {
1246                         minor = fg_console + 1;
1247                         noctty = 1;
1248                 }
1249         } else {
1250                 printk("Bad major #%d in tty_open\n", MAJOR(inode->i_rdev));
1251                 return -ENODEV;
1252         }
1253         if (minor <= 0)
1254                 return -ENXIO;
1255         if (IS_A_PTY_MASTER(minor))
1256                 noctty = 1;
1257         filp->f_rdev = (major << 8) | minor;
1258         retval = init_dev(minor);
1259         if (retval)
1260                 return retval;
1261         tty = tty_table[minor];
1262 
1263         /* clean up the packet stuff. */
1264         /*
1265          *  Why is this not done in init_dev?  Right here, if another 
1266          * process opens up a tty in packet mode, all the packet 
1267          * variables get cleared.  Come to think of it, is anything 
1268          * using the packet mode at all???  - Ted, 1/27/93
1269          */
1270         tty->status_changed = 0;
1271         tty->ctrl_status = 0;
1272         tty->packet = 0;
1273 
1274         if (tty->open) {
1275                 retval = tty->open(tty, filp);
1276         } else {
1277                 retval = -ENODEV;
1278         }
1279         if (retval) {
1280                 release_dev(minor, filp);
1281                 return retval;
1282         }
1283         if (!noctty &&
1284             current->leader &&
1285             current->tty<0 &&
1286             tty->session==0) {
1287                 current->tty = minor;
1288                 tty->session = current->session;
1289                 tty->pgrp = current->pgrp;
1290         }
1291         filp->f_rdev = 0x0400 | minor; /* Set it to something normal */
1292         return 0;
1293 }
1294 
1295 /*
1296  * Note that releasing a pty master also releases the child, so
1297  * we have to make the redirection checks after that and on both
1298  * sides of a pty.
1299  */
1300 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1301 {
1302         int dev;
1303 
1304         dev = filp->f_rdev;
1305         if (MAJOR(dev) != 4) {
1306                 printk("tty_release: tty pseudo-major != 4\n");
1307                 return;
1308         }
1309         dev = MINOR(filp->f_rdev);
1310         if (!dev) {
1311                 printk("tty_release: bad f_rdev\n");
1312                 return;
1313         }
1314         release_dev(dev, filp);
1315 }
1316 
1317 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1318 {
1319         int dev;
1320         struct tty_struct * tty;
1321 
1322         dev = filp->f_rdev;
1323         if (MAJOR(dev) != 4) {
1324                 printk("tty_select: tty pseudo-major != 4\n");
1325                 return 0;
1326         }
1327         dev = MINOR(filp->f_rdev);
1328         tty = TTY_TABLE(dev);
1329         if (!tty) {
1330                 printk("tty_select: tty struct for dev %d was NULL\n", dev);
1331                 return 0;
1332         }
1333         switch (sel_type) {
1334                 case SEL_IN:
1335                         if (L_CANON(tty)) {
1336                                 if (available_canon_input(tty))
1337                                         return 1;
1338                         } else if (!EMPTY(&tty->secondary))
1339                                 return 1;
1340                         if (tty->link) {
1341                                 if (IS_A_PTY_MASTER(tty->line)) {
1342                                         if ((tty->flags & (1 << TTY_SLAVE_OPENED))
1343                                             && tty->link->count <= 1)
1344                                                 return 1;
1345                                 } else {
1346                                         if (!tty->link->count)
1347                                                 return 1;
1348                                 }
1349                         }
1350 
1351                         /* see if the status byte can be read. */
1352                         if (tty->packet && tty->link &&
1353                             tty->link->status_changed)
1354                                 return 1;
1355 
1356                         select_wait(&tty->secondary.proc_list, wait);
1357                         return 0;
1358                 case SEL_OUT:
1359                         if (!FULL(&tty->write_q))
1360                                 return 1;
1361                         select_wait(&tty->write_q.proc_list, wait);
1362                         return 0;
1363                 case SEL_EX:
1364                         if (tty->link) {
1365                                 if (IS_A_PTY_MASTER(tty->line)) {
1366                                         if ((tty->flags & (1 << TTY_SLAVE_OPENED))
1367                                             && tty->link->count <= 1)
1368                                                 return 1;
1369                                 } else {
1370                                         if (!tty->link->count)
1371                                                 return 1;
1372                                 }
1373                         }
1374                         return 0;
1375         }
1376         return 0;
1377 }
1378 
1379 /*
1380  * This implements the "Secure Attention Key" ---  the idea is to
1381  * prevent trojan horses by killing all processes associated with this
1382  * tty when the user hits the "Secure Attention Key".  Required for
1383  * super-paranoid applications --- see the Orange Book for more details.
1384  * 
1385  * This code could be nicer; ideally it should send a HUP, wait a few
1386  * seconds, then send a INT, and then a KILL signal.  But you then
1387  * have to coordinate with the init process, since all processes associated
1388  * with the current tty must be dead before the new getty is allowed
1389  * to spawn.
1390  */
1391 void do_SAK( struct tty_struct *tty)
     /*  */
1392 {
1393         struct task_struct **p;
1394         int line = tty->line;
1395         int session = tty->session;
1396         int             i;
1397         struct file     *filp;
1398         
1399         flush_input(tty);
1400         flush_output(tty);
1401         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1402                 if (!(*p))
1403                         continue;
1404                 if (((*p)->tty == line) ||
1405                     ((session > 0) && ((*p)->session == session)))
1406                         send_sig(SIGKILL, *p, 1);
1407                 else {
1408                         for (i=0; i < NR_FILE; i++) {
1409                                 filp = (*p)->filp[i];
1410                                 if (filp && (filp->f_op == &tty_fops) &&
1411                                     (MINOR(filp->f_rdev) == line)) {
1412                                         send_sig(SIGKILL, *p, 1);
1413                                         break;
1414                                 }
1415                         }
1416                 }
1417         }
1418 }
1419 
1420 /*
1421  * This routine allows a kernel routine to send a large chunk of data
1422  * to a particular tty; if all of the data can be queued up for ouput
1423  * immediately, tty_write_data() will return 0.  If, however, not all
1424  * of the data can be immediately queued for delivery, the number of
1425  * bytes left to be queued up will be returned, and the rest of the
1426  * data will be queued up when there is room.  The callback function
1427  * will be called (with the argument callarg) when the last of the
1428  * data is finally in the queue.
1429  *
1430  * Note that the callback routine will _not_ be called if all of the
1431  * data could be queued immediately.  This is to avoid a problem with
1432  * the kernel stack getting too deep, which might happen if the
1433  * callback routine calls tty_write_data with itself as an argument.
1434  */
1435 int tty_write_data(struct tty_struct *tty, char *bufp, int buflen,
     /*  */
1436                     void (*callback)(void * data), void * callarg)
1437 {
1438         int head, tail, count;
1439         unsigned long flags;
1440         char *p;
1441 
1442 #define VLEFT ((tail-head-1)&(TTY_BUF_SIZE-1))
1443 
1444         save_flags(flags);
1445         cli();
1446         if (tty->write_data_cnt) {
1447                 restore_flags(flags);
1448                 return -EBUSY;
1449         }
1450 
1451         head = tty->write_q.head;
1452         tail = tty->write_q.tail;
1453         count = buflen;
1454         p = bufp;
1455 
1456         while (count && VLEFT > 0) {
1457                 tty->write_q.buf[head++] = *p++;
1458                 head &= TTY_BUF_SIZE-1;
1459                 count--;
1460         }
1461         tty->write_q.head = head;
1462         if (count) {
1463                 tty->write_data_cnt = count;
1464                 tty->write_data_ptr = (unsigned char *) p;
1465                 tty->write_data_callback = callback;
1466                 tty->write_data_arg = callarg;
1467         }
1468         restore_flags(flags);
1469         tty->write(tty);
1470         return count;
1471 }
1472 
1473 /*
1474  * This routine routine is called after an interrupt has drained a
1475  * tty's write queue, so that there is more space for data waiting to
1476  * be sent in tty->write_data_ptr.
1477  *
1478  * tty_check_write[8] is a bitstring which indicates which ttys
1479  * needs to be processed.
1480  */
1481 void tty_bh_routine(void * unused)
     /*  */
1482 {
1483         int     i, j, line, mask;
1484         int     head, tail, count;
1485         unsigned char * p;
1486         struct tty_struct * tty;
1487 
1488         for (i = 0, line = 0; i < MAX_TTYS / 32; i++) {
1489                 if (!tty_check_write[i]) {
1490                         line += 32;
1491                         continue;
1492                 }
1493                 for (j=0, mask=0; j < 32; j++, line++, mask <<= 1) {
1494                         if (clear_bit(j, &tty_check_write[i])) {
1495                                 tty = tty_table[line];
1496                                 if (!tty || !tty->write_data_cnt)
1497                                         continue;
1498                                 cli();
1499                                 head = tty->write_q.head;
1500                                 tail = tty->write_q.tail;
1501                                 count = tty->write_data_cnt;
1502                                 p = tty->write_data_ptr;
1503 
1504                                 while (count && VLEFT > 0) {
1505                                         tty->write_q.buf[head++] = *p++;
1506                                         head &= TTY_BUF_SIZE-1;
1507                                         count--;
1508                                 }
1509                                 tty->write_q.head = head;
1510                                 tty->write_data_ptr = p;
1511                                 tty->write_data_cnt = count;
1512                                 sti();
1513                                 if (!count)
1514                                         (tty->write_data_callback)
1515                                                 (tty->write_data_arg);
1516                         }
1517                 }
1518         }
1519         
1520 }
1521 
1522 /*
1523  * This subroutine initializes a tty structure.  We have to set up
1524  * things correctly for each different type of tty.
1525  */
1526 static void initialize_tty_struct(int line, struct tty_struct *tty)
     /*  */
1527 {
1528         memset(tty, 0, sizeof(struct tty_struct));
1529         tty->line = line;
1530         tty->disc = N_TTY;
1531         tty->pgrp = -1;
1532         tty->winsize.ws_row = 0;
1533         tty->winsize.ws_col = 0;
1534         if (IS_A_CONSOLE(line)) {
1535                 tty->open = con_open;
1536                 tty->winsize.ws_row = video_num_lines;
1537                 tty->winsize.ws_col = video_num_columns;
1538         } else if IS_A_SERIAL(line) {
1539                 tty->open = rs_open;
1540         } else if IS_A_PTY(line) {
1541                 tty->open = pty_open;
1542         }
1543 }
1544 
1545 static void initialize_termios(int line, struct termios * tp)
     /*  */
1546 {
1547         memset(tp, 0, sizeof(struct termios));
1548         memcpy(tp->c_cc, INIT_C_CC, NCCS);
1549         if (IS_A_CONSOLE(line)) {
1550                 tp->c_iflag = ICRNL | IXON;
1551                 tp->c_oflag = OPOST | ONLCR;
1552                 tp->c_cflag = B38400 | CS8 | CREAD;
1553                 tp->c_lflag = ISIG | ICANON | ECHO |
1554                         ECHOCTL | ECHOKE;
1555         } else if (IS_A_SERIAL(line)) {
1556                 tp->c_cflag = B2400 | CS8 | CREAD | HUPCL | CLOCAL;
1557                 tp->c_oflag = OPOST | ONLCR | XTABS;
1558         } else if (IS_A_PTY_MASTER(line)) {
1559                 tp->c_cflag = B9600 | CS8 | CREAD;
1560         } else if (IS_A_PTY_SLAVE(line)) {
1561                 tp->c_iflag = ICRNL | IXON;
1562                 tp->c_oflag = OPOST | ONLCR;
1563                 tp->c_cflag = B38400 | CS8 | CREAD;
1564                 tp->c_lflag = ISIG | ICANON | ECHO |
1565                         ECHOCTL | ECHOKE;
1566         }
1567 }
1568 
1569 static struct tty_ldisc tty_ldisc_N_TTY = {
1570         0,                      /* flags */
1571         NULL,                   /* open */
1572         NULL,                   /* close */
1573         read_chan,              /* read */
1574         write_chan,             /* write */
1575         NULL,                   /* ioctl */
1576         copy_to_cooked          /* handler */
1577 };
1578 
1579         
1580 long tty_init(long kmem_start)
     /*  */
1581 {
1582         int i;
1583 
1584         if (sizeof(struct tty_struct) > 4096)
1585                 panic("size of tty structure > 4096!");
1586         if (register_chrdev(4,"tty",&tty_fops))
1587                 panic("unable to get major 4 for tty device");
1588         if (register_chrdev(5,"tty",&tty_fops))
1589                 panic("unable to get major 5 for tty device");
1590         for (i=0 ; i< MAX_TTYS ; i++) {
1591                 tty_table[i] =  0;
1592                 tty_termios[i] = 0;
1593         }
1594         memset(tty_check_write, 0, sizeof(tty_check_write));
1595         bh_base[TTY_BH].routine = tty_bh_routine;
1596 
1597         /* Setup the default TTY line discipline. */
1598         memset(ldiscs, 0, sizeof(ldiscs));
1599         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1600 
1601         kmem_start = kbd_init(kmem_start);
1602         kmem_start = con_init(kmem_start);
1603         kmem_start = rs_init(kmem_start);
1604         return kmem_start;
1605 }
/* */
root/kernel/chr_drv/tty_io.c

DEFINITIONS
