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 
  33 #include <linux/types.h>
  34 #include <linux/errno.h>
  35 #include <linux/signal.h>
  36 #include <linux/fcntl.h>
  37 #include <linux/sched.h>
  38 #include <linux/tty.h>
  39 #include <linux/timer.h>
  40 #include <linux/ctype.h>
  41 #include <linux/kd.h>
  42 #include <linux/mm.h>
  43 #include <linux/string.h>
  44 #include <linux/keyboard.h>
  45 
  46 #include <asm/segment.h>
  47 #include <asm/system.h>
  48 #include <asm/bitops.h>
  49 
  50 #include "vt_kern.h"
  51 
  52 #define MAX_TTYS 256
  53 
  54 struct tty_struct *tty_table[MAX_TTYS];
  55 struct termios *tty_termios[MAX_TTYS]; /* We need to keep the termios state */
  56                                   /* around, even when a tty is closed */
  57 struct tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
  58 int tty_check_write[MAX_TTYS/32];       /* bitfield for the bh handler */
  59 
  60 /*
  61  * fg_console is the current virtual console,
  62  * redirect is the pseudo-tty that console output
  63  * is redirected to if asked by TIOCCONS.
  64  */
  65 int fg_console = 0;
  66 struct tty_struct * redirect = NULL;
  67 struct wait_queue * keypress_wait = NULL;
  68 
  69 static void initialize_tty_struct(int line, struct tty_struct *tty);
  70 static void initialize_termios(int line, struct termios *tp);
  71 
  72 static int tty_read(struct inode *, struct file *, char *, int);
  73 static int tty_write(struct inode *, struct file *, char *, int);
  74 static int tty_select(struct inode *, struct file *, int, select_table *);
  75 static int tty_open(struct inode *, struct file *);
  76 static void tty_release(struct inode *, struct file *);
  77 
  78 int tty_register_ldisc(int disc, struct tty_ldisc *new)
     /*  */
  79 {
  80         if (disc < N_TTY || disc >= NR_LDISCS)
  81                 return -EINVAL;
  82         
  83         if (new) {
  84                 ldiscs[disc] = *new;
  85                 ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
  86         } else
  87                 memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
  88         
  89         return 0;
  90 }
  91 
  92 void put_tty_queue(char c, struct tty_queue * queue)
     /*  */
  93 {
  94         int head;
  95         unsigned long flags;
  96 
  97         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
  98         head = (queue->head + 1) & (TTY_BUF_SIZE-1);
  99         if (head != queue->tail) {
 100                 queue->buf[queue->head] = c;
 101                 queue->head = head;
 102         }
 103         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
 104 }
 105 
 106 int get_tty_queue(struct tty_queue * queue)
     /*  */
 107 {
 108         int result = -1;
 109         unsigned long flags;
 110 
 111         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
 112         if (queue->tail != queue->head) {
 113                 result = 0xff & queue->buf[queue->tail];
 114                 queue->tail = (queue->tail + 1) & (TTY_BUF_SIZE-1);
 115         }
 116         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
 117         return result;
 118 }
 119 
 120 /*
 121  * This routine copies out a maximum of buflen characters from the
 122  * read_q; it is a convenience for line disciplins so they can grab a
 123  * large block of data without calling get_tty_char directly.  It
 124  * returns the number of characters actually read.
 125  */
 126 int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp, int buflen)
     /*  */
 127 {
 128         int     result = 0;
 129         unsigned char   *p = bufp;
 130         unsigned long flags;
 131         int head, tail;
 132         
 133         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
 134         tail = tty->read_q.tail;
 135         head = tty->read_q.head;
 136         while ((result < buflen) && (tail!=head)) {
 137                 *p++ =  tty->read_q.buf[tail++];
 138                 tail &= TTY_BUF_SIZE-1;
 139                 result++;
 140         }
 141         tty->read_q.tail = tail;
 142         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
 143         return result;
 144 }
 145 
 146 
 147 void tty_write_flush(struct tty_struct * tty)
     /*  */
 148 {
 149         if (!tty->write || EMPTY(&tty->write_q))
 150                 return;
 151         if (set_bit(TTY_WRITE_BUSY,&tty->flags))
 152                 return;
 153         tty->write(tty);
 154         if (clear_bit(TTY_WRITE_BUSY,&tty->flags))
 155                 printk("tty_write_flush: bit already cleared\n");
 156 }
 157 
 158 void tty_read_flush(struct tty_struct * tty)
     /*  */
 159 {
 160         if (!tty || EMPTY(&tty->read_q))
 161                 return;
 162         if (set_bit(TTY_READ_BUSY, &tty->flags))
 163                 return;
 164         ldiscs[tty->disc].handler(tty);
 165         if (clear_bit(TTY_READ_BUSY, &tty->flags))
 166                 printk("tty_read_flush: bit already cleared\n");
 167 }
 168 
 169 static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 170 {
 171         return 0;
 172 }
 173 
 174 static int hung_up_tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 175 {
 176         return -EIO;
 177 }
 178 
 179 static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
 180 {
 181         return 1;
 182 }
 183 
 184 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
     /*  */
 185                              unsigned int cmd, unsigned int arg)
 186 {
 187         return -EIO;
 188 }
 189 
 190 static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 191 {
 192         return -ESPIPE;
 193 }
 194 
 195 static struct file_operations tty_fops = {
 196         tty_lseek,
 197         tty_read,
 198         tty_write,
 199         NULL,           /* tty_readdir */
 200         tty_select,
 201         tty_ioctl,
 202         NULL,           /* tty_mmap */
 203         tty_open,
 204         tty_release
 205 };
 206 
 207 static struct file_operations hung_up_tty_fops = {
 208         tty_lseek,
 209         hung_up_tty_read,
 210         hung_up_tty_write,
 211         NULL,           /* hung_up_tty_readdir */
 212         hung_up_tty_select,
 213         tty_ioctl,
 214         NULL,           /* hung_up_tty_mmap */
 215         tty_open,
 216         tty_release
 217 };
 218 
 219 static struct file_operations vhung_up_tty_fops = {
 220         tty_lseek,
 221         hung_up_tty_read,
 222         hung_up_tty_write,
 223         NULL,           /* hung_up_tty_readdir */
 224         hung_up_tty_select,
 225         hung_up_tty_ioctl,
 226         NULL,           /* hung_up_tty_mmap */
 227         tty_open,
 228         tty_release
 229 };
 230 
 231 void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
     /*  */
 232 {
 233         struct file * filp;
 234         struct task_struct **p;
 235         int dev;
 236 
 237         if (!tty)
 238                 return;
 239         dev = 0x0400 + tty->line;
 240         filp = file_table + NR_FILE;
 241         while (filp-- > file_table) {
 242                 if (!filp->f_count)
 243                         continue;
 244                 if (filp->f_rdev != dev)
 245                         continue;
 246                 if (filp->f_op != &tty_fops)
 247                         continue;
 248                 filp->f_op = fops;
 249         }
 250         wake_up_interruptible(&tty->secondary.proc_list);
 251         wake_up_interruptible(&tty->read_q.proc_list);
 252         wake_up_interruptible(&tty->write_q.proc_list);
 253         if (tty->session > 0)
 254                 kill_sl(tty->session,SIGHUP,1);
 255         tty->session = 0;
 256         tty->pgrp = -1;
 257         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
 258                 if ((*p) && (*p)->tty == tty->line)
 259                         (*p)->tty = -1;
 260         }
 261 }
 262 
 263 void tty_hangup(struct tty_struct * tty)
     /*  */
 264 {
 265         do_tty_hangup(tty, &hung_up_tty_fops);
 266 }
 267 
 268 void tty_vhangup(struct tty_struct * tty)
     /*  */
 269 {
 270         do_tty_hangup(tty, &vhung_up_tty_fops);
 271 }
 272 
 273 void tty_unhangup(struct file *filp)
     /*  */
 274 {
 275         filp->f_op = &tty_fops;
 276 }
 277 
 278 inline int tty_hung_up_p(struct file * filp)
     /*  */
 279 {
 280         return ((filp->f_op == &hung_up_tty_fops) ||
 281                 (filp->f_op == &vhung_up_tty_fops));
 282 }
 283 
 284 /*
 285  * Sometimes we want to wait until a particular VT has been activated. We
 286  * do it in a very simple manner. Everybody waits on a single queue and
 287  * get woken up at once. Those that are satisfied go on with their business,
 288  * while those not ready go back to sleep. Seems overkill to add a wait
 289  * to each vt just for this - usually this does nothing!
 290  */
 291 static struct wait_queue *vt_activate_queue = NULL;
 292 
 293 /*
 294  * Sleeps until a vt is activated, or the task is interrupted. Returns
 295  * 0 if activation, -1 if interrupted.
 296  */
 297 int vt_waitactive(void)
     /*  */
 298 {
 299         interruptible_sleep_on(&vt_activate_queue);
 300         return (current->signal & ~current->blocked) ? -1 : 0;
 301 }
 302 
 303 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 304 
 305 extern int kill_proc(int pid, int sig, int priv);
 306 
 307 /*
 308  * Performs the back end of a vt switch
 309  */
 310 void complete_change_console(unsigned int new_console)
     /*  */
 311 {
 312         unsigned char old_vc_mode;
 313 
 314         if (new_console == fg_console || new_console >= NR_CONSOLES)
 315                 return;
 316 
 317         /*
 318          * If we're switching, we could be going from KD_GRAPHICS to
 319          * KD_TEXT mode or vice versa, which means we need to blank or
 320          * unblank the screen later.
 321          */
 322         old_vc_mode = vt_cons[fg_console].vc_mode;
 323         update_screen(new_console);
 324 
 325         /*
 326          * If this new console is under process control, send it a signal
 327          * telling it that it has acquired. Also check if it has died and
 328          * clean up (similar to logic employed in change_console())
 329          */
 330         if (vt_cons[new_console].vt_mode.mode == VT_PROCESS)
 331         {
 332                 /*
 333                  * Send the signal as privileged - kill_proc() will
 334                  * tell us if the process has gone or something else
 335                  * is awry
 336                  */
 337                 if (kill_proc(vt_cons[new_console].vt_pid,
 338                               vt_cons[new_console].vt_mode.acqsig,
 339                               1) != 0)
 340                 {
 341                 /*
 342                  * The controlling process has died, so we revert back to
 343                  * normal operation. In this case, we'll also change back
 344                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 345                  * but it saves the agony when the X server dies and the screen
 346                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 347                  * this outside of VT_PROCESS but there is no single process
 348                  * to account for and tracking tty count may be undesirable.
 349                  */
 350                         vt_cons[new_console].vc_mode = KD_TEXT;
 351                         clr_vc_kbd_flag(kbd_table + new_console, VC_RAW);
 352                         vt_cons[new_console].vt_mode.mode = VT_AUTO;
 353                         vt_cons[new_console].vt_mode.waitv = 0;
 354                         vt_cons[new_console].vt_mode.relsig = 0;
 355                         vt_cons[new_console].vt_mode.acqsig = 0;
 356                         vt_cons[new_console].vt_mode.frsig = 0;
 357                         vt_cons[new_console].vt_pid = -1;
 358                         vt_cons[new_console].vt_newvt = -1;
 359                 }
 360         }
 361 
 362         /*
 363          * We do this here because the controlling process above may have
 364          * gone, and so there is now a new vc_mode
 365          */
 366         if (old_vc_mode != vt_cons[new_console].vc_mode)
 367         {
 368                 if (vt_cons[new_console].vc_mode == KD_TEXT)
 369                         unblank_screen();
 370                 else
 371                 {
 372                         timer_active &= ~(1<<BLANK_TIMER);
 373                         blank_screen();
 374                 }
 375         }
 376 
 377         /*
 378          * Wake anyone waiting for their VT to activate
 379          */
 380         vt_wake_waitactive();
 381         return;
 382 }
 383 
 384 /*
 385  * Performs the front-end of a vt switch
 386  */
 387 void change_console(unsigned int new_console)
     /*  */
 388 {
 389         if (new_console == fg_console || new_console >= NR_CONSOLES)
 390                 return;
 391 
 392         /*
 393          * If this vt is in process mode, then we need to handshake with
 394          * that process before switching. Essentially, we store where that
 395          * vt wants to switch to and wait for it to tell us when it's done
 396          * (via VT_RELDISP ioctl).
 397          *
 398          * We also check to see if the controlling process still exists.
 399          * If it doesn't, we reset this vt to auto mode and continue.
 400          * This is a cheap way to track process control. The worst thing
 401          * that can happen is: we send a signal to a process, it dies, and
 402          * the switch gets "lost" waiting for a response; hopefully, the
 403          * user will try again, we'll detect the process is gone (unless
 404          * the user waits just the right amount of time :-) and revert the
 405          * vt to auto control.
 406          */
 407         if (vt_cons[fg_console].vt_mode.mode == VT_PROCESS)
 408         {
 409                 /*
 410                  * Send the signal as privileged - kill_proc() will
 411                  * tell us if the process has gone or something else
 412                  * is awry
 413                  */
 414                 if (kill_proc(vt_cons[fg_console].vt_pid,
 415                               vt_cons[fg_console].vt_mode.relsig,
 416                               1) == 0)
 417                 {
 418                         /*
 419                          * It worked. Mark the vt to switch to and
 420                          * return. The process needs to send us a
 421                          * VT_RELDISP ioctl to complete the switch.
 422                          */
 423                         vt_cons[fg_console].vt_newvt = new_console;
 424                         return;
 425                 }
 426 
 427                 /*
 428                  * The controlling process has died, so we revert back to
 429                  * normal operation. In this case, we'll also change back
 430                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 431                  * but it saves the agony when the X server dies and the screen
 432                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 433                  * this outside of VT_PROCESS but there is no single process
 434                  * to account for and tracking tty count may be undesirable.
 435                  */
 436                 vt_cons[fg_console].vc_mode = KD_TEXT;
 437                 clr_vc_kbd_flag(kbd_table + fg_console, VC_RAW);
 438                 vt_cons[fg_console].vt_mode.mode = VT_AUTO;
 439                 vt_cons[fg_console].vt_mode.waitv = 0;
 440                 vt_cons[fg_console].vt_mode.relsig = 0;
 441                 vt_cons[fg_console].vt_mode.acqsig = 0;
 442                 vt_cons[fg_console].vt_mode.frsig = 0;
 443                 vt_cons[fg_console].vt_pid = -1;
 444                 vt_cons[fg_console].vt_newvt = -1;
 445                 /*
 446                  * Fall through to normal (VT_AUTO) handling of the switch...
 447                  */
 448         }
 449 
 450         /*
 451          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 452          */
 453         if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
 454                 return;
 455 
 456         complete_change_console(new_console);
 457 }
 458 
 459 void wait_for_keypress(void)
     /*  */
 460 {
 461         sleep_on(&keypress_wait);
 462 }
 463 
 464 void copy_to_cooked(struct tty_struct * tty)
     /*  */
 465 {
 466         int c, special_flag;
 467         unsigned long flags;
 468 
 469         if (!tty) {
 470                 printk("copy_to_cooked: called with NULL tty\n");
 471                 return;
 472         }
 473         if (!tty->write) {
 474                 printk("copy_to_cooked: tty %d has null write routine\n",
 475                        tty->line);
 476         }
 477         while (1) {
 478                 /*
 479                  * Check to see how much room we have left in the
 480                  * secondary queue.  Send a throttle command or abort
 481                  * if necessary.
 482                  */
 483                 c = LEFT(&tty->secondary);
 484                 if (tty->throttle && (c < SQ_THRESHOLD_LW)
 485                     && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
 486                         tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
 487                 if (c == 0)
 488                         break;
 489                 save_flags(flags); cli();
 490                 if (tty->read_q.tail != tty->read_q.head) {
 491                         c = 0xff & tty->read_q.buf[tty->read_q.tail];
 492                         special_flag = !clear_bit(tty->read_q.tail,
 493                                                   &tty->readq_flags);
 494                         tty->read_q.tail = (tty->read_q.tail + 1) &
 495                                 (TTY_BUF_SIZE-1);
 496                         restore_flags(flags);
 497                 } else {
 498                         restore_flags(flags);
 499                         break;
 500                 }
 501                 if (special_flag) {
 502                         tty->char_error = c & 3;
 503                         continue;
 504                 }
 505                 if (tty->char_error) {
 506                         if (tty->char_error == TTY_BREAK) {
 507                                 tty->char_error = 0;
 508                                 if (I_IGNBRK(tty))
 509                                         continue;
 510                                 if (I_PARMRK(tty)) {
 511                                         put_tty_queue(0377, &tty->secondary);
 512                                         put_tty_queue(0, &tty->secondary);
 513                                 }
 514                                 put_tty_queue(0, &tty->secondary);
 515                                 continue;
 516                         }
 517                         /* If not a break, then a parity or frame error */
 518                         tty->char_error = 0;
 519                         if (I_IGNPAR(tty)) {
 520                                 continue;
 521                         }
 522                         if (I_PARMRK(tty)) {
 523                                 put_tty_queue(0377, &tty->secondary);
 524                                 put_tty_queue(0, &tty->secondary);
 525                                 put_tty_queue(c, &tty->secondary);
 526                         } else
 527                                 put_tty_queue(0, &tty->secondary);
 528                         continue;
 529                 }
 530                 if (I_STRP(tty))
 531                         c &= 0x7f;
 532                 else if (I_PARMRK(tty) && (c == 0377))
 533                         put_tty_queue(0377, &tty->secondary);
 534                 if (c==13) {
 535                         if (I_CRNL(tty))
 536                                 c=10;
 537                         else if (I_NOCR(tty))
 538                                 continue;
 539                 } else if (c==10 && I_NLCR(tty))
 540                         c=13;
 541                 if (I_UCLC(tty))
 542                         c=tolower(c);
 543                 if (c == __DISABLED_CHAR)
 544                         tty->lnext = 1;
 545                 if (L_CANON(tty) && !tty->lnext) {
 546                         if (c == KILL_CHAR(tty)) {
 547                                 /* deal with killing the input line */
 548                                 while(!(EMPTY(&tty->secondary) ||
 549                                         (c=LAST(&tty->secondary))==10 ||
 550                                         ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 551                                          (c==EOF_CHAR(tty))))) {
 552                                         if (L_ECHO(tty)) {
 553                                                 if (c<32) {
 554                                                         put_tty_queue(8, &tty->write_q);
 555                                                         put_tty_queue(' ', &tty->write_q);
 556                                                         put_tty_queue(8,&tty->write_q);
 557                                                 }
 558                                                 put_tty_queue(8,&tty->write_q);
 559                                                 put_tty_queue(' ',&tty->write_q);
 560                                                 put_tty_queue(8,&tty->write_q);
 561                                         }
 562                                         DEC(tty->secondary.head);
 563                                 }
 564                                 continue;
 565                         }
 566                         if (c == ERASE_CHAR(tty)) {
 567                                 if (EMPTY(&tty->secondary) ||
 568                                    (c=LAST(&tty->secondary))==10 ||
 569                                    ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 570                                     (c==EOF_CHAR(tty))))
 571                                         continue;
 572                                 if (L_ECHO(tty)) {
 573                                         if (c<32) {
 574                                                 put_tty_queue(8,&tty->write_q);
 575                                                 put_tty_queue(' ',&tty->write_q);
 576                                                 put_tty_queue(8,&tty->write_q);
 577                                         }
 578                                         put_tty_queue(8,&tty->write_q);
 579                                         put_tty_queue(32,&tty->write_q);
 580                                         put_tty_queue(8,&tty->write_q);
 581                                 }
 582                                 DEC(tty->secondary.head);
 583                                 continue;
 584                         }
 585                         if (c == LNEXT_CHAR(tty)) {
 586                                 tty->lnext = 1;
 587                                 if (L_ECHO(tty)) {
 588                                         put_tty_queue('^',&tty->write_q);
 589                                         put_tty_queue(8,&tty->write_q);
 590                                 }
 591                                 continue;
 592                         }
 593                 }
 594                 if (I_IXON(tty) && !tty->lnext) {
 595                         if (c == STOP_CHAR(tty)) {
 596                                 tty->status_changed = 1;
 597                                 tty->ctrl_status |= TIOCPKT_STOP;
 598                                 tty->stopped=1;
 599                                 continue;
 600                         }
 601                         if (((I_IXANY(tty)) && tty->stopped) ||
 602                             (c == START_CHAR(tty))) {
 603                                 tty->status_changed = 1;
 604                                 tty->ctrl_status |= TIOCPKT_START;
 605                                 tty->stopped=0;
 606                                 continue;
 607                         }
 608                 }
 609                 if (L_ISIG(tty) && !tty->lnext) {
 610                         if (c == INTR_CHAR(tty)) {
 611                                 kill_pg(tty->pgrp, SIGINT, 1);
 612                                 flush_input(tty);
 613                                 continue;
 614                         }
 615                         if (c == QUIT_CHAR(tty)) {
 616                                 kill_pg(tty->pgrp, SIGQUIT, 1);
 617                                 flush_input(tty);
 618                                 continue;
 619                         }
 620                         if (c == SUSPEND_CHAR(tty)) {
 621                                 if (!is_orphaned_pgrp(tty->pgrp))
 622                                         kill_pg(tty->pgrp, SIGTSTP, 1);
 623                                 continue;
 624                         }
 625                 }
 626                 if (c==10 || (EOF_CHAR(tty) != __DISABLED_CHAR &&
 627                     c==EOF_CHAR(tty)))
 628                         tty->secondary.data++;
 629                 if ((c==10) && (L_ECHO(tty) || (L_CANON(tty) && L_ECHONL(tty)))) {
 630                         put_tty_queue(10,&tty->write_q);
 631                         put_tty_queue(13,&tty->write_q);
 632                 } else if (L_ECHO(tty)) {
 633                         if (c<32 && L_ECHOCTL(tty)) {
 634                                 put_tty_queue('^',&tty->write_q);
 635                                 put_tty_queue(c+64, &tty->write_q);
 636                                 if (EOF_CHAR(tty) != __DISABLED_CHAR &&
 637                                     c==EOF_CHAR(tty) && !tty->lnext) {
 638                                         put_tty_queue(8,&tty->write_q);
 639                                         put_tty_queue(8,&tty->write_q);
 640                                 }
 641                         } else
 642                                 put_tty_queue(c, &tty->write_q);
 643                 }
 644                 tty->lnext = 0;
 645                 put_tty_queue(c, &tty->secondary);
 646         }
 647         TTY_WRITE_FLUSH(tty);
 648         if (!EMPTY(&tty->secondary))
 649                 wake_up_interruptible(&tty->secondary.proc_list);
 650         if (tty->write_q.proc_list && LEFT(&tty->write_q) > TTY_BUF_SIZE/2)
 651                 wake_up_interruptible(&tty->write_q.proc_list);
 652         if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
 653             && !clear_bit(TTY_RQ_THROTTLED, &tty->flags))
 654                 tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
 655         if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 656             && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 657                 tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 658 }
 659 
 660 int is_ignored(int sig)
     /*  */
 661 {
 662         return ((current->blocked & (1<<(sig-1))) ||
 663                 (current->sigaction[sig-1].sa_handler == SIG_IGN));
 664 }
 665 
 666 static int available_canon_input(struct tty_struct *);
 667 static void __wait_for_canon_input(struct file * file, struct tty_struct *);
 668 
 669 static void wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 670 {
 671         if (!available_canon_input(tty)) {
 672                 if (current->signal & ~current->blocked)
 673                         return;
 674                 __wait_for_canon_input(file, tty);
 675         }
 676 }
 677 
 678 static int read_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 679 {
 680         struct wait_queue wait = { current, NULL };
 681         int c;
 682         char * b=buf;
 683         int minimum,time;
 684 
 685         if (L_CANON(tty))
 686                 minimum = time = current->timeout = 0;
 687         else {
 688                 time = 10L*tty->termios->c_cc[VTIME];
 689                 minimum = tty->termios->c_cc[VMIN];
 690                 if (minimum)
 691                         current->timeout = 0xffffffff;
 692                 else {
 693                         if (time)
 694                                 current->timeout = time + jiffies;
 695                         else
 696                                 current->timeout = 0;
 697                         time = 0;
 698                         minimum = 1;
 699                 }
 700         }
 701         if (file->f_flags & O_NONBLOCK) {
 702                 time = current->timeout = 0;
 703                 if (L_CANON(tty)) {
 704                         if (!available_canon_input(tty))
 705                                 return -EAGAIN;
 706                 }
 707         } else if (L_CANON(tty)) {
 708                 wait_for_canon_input(file, tty);
 709                 if (current->signal & ~current->blocked)
 710                         return -ERESTARTSYS;
 711         }
 712         if (minimum>nr)
 713                 minimum = nr;
 714 
 715         /* deal with packet mode:  First test for status change */
 716         if (tty->packet && tty->link && tty->link->status_changed) {
 717                 put_fs_byte (tty->link->ctrl_status, b);
 718                 tty->link->status_changed = 0;
 719                 return 1;
 720         }
 721           
 722         /* now bump the buffer up one. */
 723         if (tty->packet) {
 724                 put_fs_byte (0,b++);
 725                 nr--;
 726                 /* this really shouldn't happen, but we need to 
 727                 put it here. */
 728                 if (nr == 0)
 729                         return 1;
 730         }
 731         add_wait_queue(&tty->secondary.proc_list, &wait);
 732         while (nr>0) {
 733                 if (tty_hung_up_p(file)) {
 734                         file->f_flags &= ~O_NONBLOCK;
 735                         break;  /* force read() to return 0 */
 736                 }
 737                 TTY_READ_FLUSH(tty);
 738                 if (tty->link)
 739                         TTY_WRITE_FLUSH(tty->link);
 740                 while (nr > 0 && ((c = get_tty_queue(&tty->secondary)) >= 0)) {
 741                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 742                              c==EOF_CHAR(tty)) || c==10)
 743                                 tty->secondary.data--;
 744                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 745                              c==EOF_CHAR(tty)) && L_CANON(tty))
 746                                 break;
 747                         put_fs_byte(c,b++);
 748                         nr--;
 749                         if (time)
 750                                 current->timeout = time+jiffies;
 751                         if (c==10 && L_CANON(tty))
 752                                 break;
 753                 };
 754                 wake_up_interruptible(&tty->read_q.proc_list);
 755                 /*
 756                  * If there is enough space in the secondary queue
 757                  * now, let the low-level driver know.
 758                  */
 759                 if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 760                     && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 761                         tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 762                 if (b-buf >= minimum || !current->timeout)
 763                         break;
 764                 if (current->signal & ~current->blocked) 
 765                         break;
 766                 if (tty->link && !tty->link->count)
 767                         break;
 768                 TTY_READ_FLUSH(tty);
 769                 if (tty->link)
 770                         TTY_WRITE_FLUSH(tty->link);
 771                 if (!EMPTY(&tty->secondary))
 772                         continue;
 773                 current->state = TASK_INTERRUPTIBLE;
 774                 if (EMPTY(&tty->secondary))
 775                         schedule();
 776                 current->state = TASK_RUNNING;
 777         }
 778         remove_wait_queue(&tty->secondary.proc_list, &wait);
 779         TTY_READ_FLUSH(tty);
 780         if (tty->link && tty->link->write)
 781                 TTY_WRITE_FLUSH(tty->link);
 782         current->timeout = 0;
 783 
 784         /* packet mode sticks in an extra 0.  If that's all we've got,
 785            we should count it a zero bytes. */
 786         if (tty->packet) {
 787                 if ((b-buf) > 1)
 788                         return b-buf;
 789         } else {
 790                 if (b-buf)
 791                         return b-buf;
 792         }
 793 
 794         if (current->signal & ~current->blocked)
 795                 return -ERESTARTSYS;
 796         if (file->f_flags & O_NONBLOCK)
 797                 return -EAGAIN;
 798         return 0;
 799 }
 800 
 801 static void __wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 802 {
 803         struct wait_queue wait = { current, NULL };
 804 
 805         add_wait_queue(&tty->secondary.proc_list, &wait);
 806         while (1) {
 807                 current->state = TASK_INTERRUPTIBLE;
 808                 if (available_canon_input(tty))
 809                         break;
 810                 if (current->signal & ~current->blocked)
 811                         break;
 812                 if (tty_hung_up_p(file))
 813                         break;
 814                 schedule();
 815         }
 816         current->state = TASK_RUNNING;
 817         remove_wait_queue(&tty->secondary.proc_list, &wait);
 818 }
 819 
 820 static int available_canon_input(struct tty_struct * tty)
     /*  */
 821 {
 822         TTY_READ_FLUSH(tty);
 823         if (tty->link)
 824                 if (tty->link->count)
 825                         TTY_WRITE_FLUSH(tty->link);
 826                 else
 827                         return 1;
 828         if (FULL(&tty->read_q))
 829                 return 1;
 830         if (tty->secondary.data)
 831                 return 1;
 832         return 0;
 833 }
 834 
 835 static int write_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 836 {
 837         struct wait_queue wait = { current, NULL };
 838         char c, *b=buf;
 839 
 840         if (nr < 0)
 841                 return -EINVAL;
 842         if (!nr)
 843                 return 0;
 844         add_wait_queue(&tty->write_q.proc_list, &wait);
 845         while (nr>0) {
 846                 if (current->signal & ~current->blocked)
 847                         break;
 848                 if (tty_hung_up_p(file))
 849                         break;
 850                 if (tty->link && !tty->link->count) {
 851                         send_sig(SIGPIPE,current,0);
 852                         break;
 853                 }
 854                 current->state = TASK_INTERRUPTIBLE;
 855                 if (FULL(&tty->write_q)) {
 856                         TTY_WRITE_FLUSH(tty);
 857                         if (FULL(&tty->write_q))
 858                                 schedule();
 859                         current->state = TASK_RUNNING;
 860                         continue;
 861                 }
 862                 current->state = TASK_RUNNING;
 863                 while (nr>0 && !FULL(&tty->write_q)) {
 864                         c=get_fs_byte(b);
 865                         if (O_POST(tty)) {
 866                                 if (c=='\r' && O_CRNL(tty))
 867                                         c='\n';
 868                                 else if (c=='\n' && O_NLRET(tty))
 869                                         c='\r';
 870                                 if (c=='\n' && O_NLCR(tty) &&
 871                                     !set_bit(TTY_CR_PENDING,&tty->flags)) {
 872                                         put_tty_queue(13,&tty->write_q);
 873                                         continue;
 874                                 }
 875                                 if (O_LCUC(tty))
 876                                         c=toupper(c);
 877                         }
 878                         b++; nr--;
 879                         clear_bit(TTY_CR_PENDING,&tty->flags);
 880                         put_tty_queue(c,&tty->write_q);
 881                 }
 882                 if (need_resched)
 883                         schedule();
 884         }
 885         remove_wait_queue(&tty->write_q.proc_list, &wait);
 886         TTY_WRITE_FLUSH(tty);
 887         if (b-buf)
 888                 return b-buf;
 889         if (tty->link && !tty->link->count)
 890                 return -EPIPE;
 891         if (current->signal & ~current->blocked)
 892                 return -ERESTARTSYS;
 893         return 0;
 894 }
 895 
 896 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 897 {
 898         int i, dev;
 899         struct tty_struct * tty;
 900 
 901         dev = file->f_rdev;
 902         if (MAJOR(dev) != 4) {
 903                 printk("tty_read: bad pseudo-major nr #%d\n", MAJOR(dev));
 904                 return -EINVAL;
 905         }
 906         dev = MINOR(dev);
 907         tty = TTY_TABLE(dev);
 908         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 909                 return -EIO;
 910         if ((inode->i_rdev != 0x0400) && /* don't stop on /dev/console */
 911             (tty->pgrp > 0) &&
 912             (current->tty == dev) &&
 913             (tty->pgrp != current->pgrp))
 914                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 915                         return -EIO;
 916                 else {
 917                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 918                         return -ERESTARTSYS;
 919                 }
 920         if (ldiscs[tty->disc].read)
 921                 i = (ldiscs[tty->disc].read)(tty,file,buf,count);
 922         else
 923                 i = -EIO;
 924         if (i > 0)
 925                 inode->i_atime = CURRENT_TIME;
 926         return i;
 927 }
 928 
 929 static int tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 930 {
 931         int dev, i, is_console;
 932         struct tty_struct * tty;
 933 
 934         dev = file->f_rdev;
 935         is_console = (inode->i_rdev == 0x0400);
 936         if (MAJOR(dev) != 4) {
 937                 printk("tty_write: pseudo-major != 4\n");
 938                 return -EINVAL;
 939         }
 940         dev = MINOR(dev);
 941         if (is_console && redirect)
 942                 tty = redirect;
 943         else
 944                 tty = TTY_TABLE(dev);
 945         if (!tty || !tty->write || (tty->flags & (1 << TTY_IO_ERROR)))
 946                 return -EIO;
 947         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
 948             (current->tty == dev) && (tty->pgrp != current->pgrp)) {
 949                 if (is_orphaned_pgrp(current->pgrp))
 950                         return -EIO;
 951                 if (!is_ignored(SIGTTOU)) {
 952                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
 953                         return -ERESTARTSYS;
 954                 }
 955         }
 956         if (ldiscs[tty->disc].write)
 957                 i = (ldiscs[tty->disc].write)(tty,file,buf,count);
 958         else
 959                 i = -EIO;
 960         if (i > 0)
 961                 inode->i_mtime = CURRENT_TIME;
 962         return i;
 963 }
 964 
 965 /*
 966  * This is so ripe with races that you should *really* not touch this
 967  * unless you know exactly what you are doing. All the changes have to be
 968  * made atomically, or there may be incorrect pointers all over the place.
 969  */
 970 static int init_dev(int dev)
     /*  */
 971 {
 972         struct tty_struct *tty, *o_tty;
 973         struct termios *tp, *o_tp;
 974         int retval;
 975         int o_dev;
 976 
 977         o_dev = PTY_OTHER(dev);
 978         tty = o_tty = NULL;
 979         tp = o_tp = NULL;
 980 repeat:
 981         retval = -EAGAIN;
 982         if (IS_A_PTY_MASTER(dev) && tty_table[dev] && tty_table[dev]->count)
 983                 goto end_init;
 984         retval = -ENOMEM;
 985         if (!tty_table[dev] && !tty) {
 986                 tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
 987                 if (!tty)
 988                         goto end_init;
 989                 initialize_tty_struct(dev, tty);
 990                 goto repeat;
 991         }
 992         if (!tty_termios[dev] && !tp) {
 993                 tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
 994                 if (!tp)
 995                         goto end_init;
 996                 initialize_termios(dev, tp);
 997                 goto repeat;
 998         }
 999         if (IS_A_PTY(dev)) {
1000                 if (!tty_table[o_dev] && !o_tty) {
1001                         o_tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
1002                         if (!o_tty)
1003                                 goto end_init;
1004                         initialize_tty_struct(o_dev, o_tty);
1005                         goto repeat;
1006                 }
1007                 if (!tty_termios[o_dev] && !o_tp) {
1008                         o_tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
1009                         if (!o_tp)
1010                                 goto end_init;
1011                         initialize_termios(o_dev, o_tp);
1012                         goto repeat;
1013                 }
1014         }
1015         /* Now we have allocated all the structures: update all the pointers.. */
1016         if (!tty_termios[dev]) {
1017                 tty_termios[dev] = tp;
1018                 tp = NULL;
1019         }
1020         if (!tty_table[dev]) {
1021                 tty->termios = tty_termios[dev];
1022                 tty_table[dev] = tty;
1023                 tty = NULL;
1024         }
1025         if (IS_A_PTY(dev)) {
1026                 if (!tty_termios[o_dev]) {
1027                         tty_termios[o_dev] = o_tp;
1028                         o_tp = NULL;
1029                 }
1030                 if (!tty_table[o_dev]) {
1031                         o_tty->termios = tty_termios[o_dev];
1032                         tty_table[o_dev] = o_tty;
1033                         o_tty = NULL;
1034                 }
1035                 tty_table[dev]->link = tty_table[o_dev];
1036                 tty_table[o_dev]->link = tty_table[dev];
1037         }
1038         tty_table[dev]->count++;
1039         if (IS_A_PTY_MASTER(dev))
1040                 tty_table[o_dev]->count++;
1041         retval = 0;
1042 end_init:
1043         if (tty)
1044                 free_page((unsigned long) tty);
1045         if (o_tty)
1046                 free_page((unsigned long) tty);
1047         if (tp)
1048                 kfree_s(tp, sizeof(struct termios));
1049         if (o_tp)
1050                 kfree_s(o_tp, sizeof(struct termios));
1051         return retval;
1052 }
1053 
1054 /*
1055  * Even releasing the tty structures is a tricky business.. We have
1056  * to be very careful that the structures are all released at the
1057  * same time, as interrupts might otherwise get the wrong pointers.
1058  */
1059 static void release_dev(int dev, struct file * filp)
     /*  */
1060 {
1061         struct tty_struct *tty, *o_tty;
1062         struct termios *tp, *o_tp;
1063         struct task_struct **p;
1064 
1065         tty = tty_table[dev];
1066         tp = tty_termios[dev];
1067         o_tty = NULL;
1068         o_tp = NULL;
1069         if (!tty) {
1070                 printk("release_dev: tty_table[%d] was NULL\n", dev);
1071                 return;
1072         }
1073         if (!tp) {
1074                 printk("release_dev: tty_termios[%d] was NULL\n", dev);
1075                 return;
1076         }
1077         if (IS_A_PTY(dev)) {
1078                 o_tty = tty_table[PTY_OTHER(dev)];
1079                 o_tp = tty_termios[PTY_OTHER(dev)];
1080                 if (!o_tty) {
1081                         printk("release_dev: pty pair(%d) was NULL\n", dev);
1082                         return;
1083                 }
1084                 if (!o_tp) {
1085                         printk("release_dev: pty pair(%d) termios was NULL\n", dev);
1086                         return;
1087                 }
1088                 if (tty->link != o_tty || o_tty->link != tty) {
1089                         printk("release_dev: bad pty pointers\n");
1090                         return;
1091                 }
1092         }
1093         tty->write_data_cnt = 0; /* Clear out pending trash */
1094         if (tty->close)
1095                 tty->close(tty, filp);
1096         if (IS_A_PTY_MASTER(dev)) {
1097                 if (--tty->link->count < 0) {
1098                         printk("release_dev: bad tty slave count (dev = %d): %d\n",
1099                                dev, tty->count);
1100                         tty->link->count = 0;
1101                 }
1102         }
1103         if (--tty->count < 0) {
1104                 printk("release_dev: bad tty_table[%d]->count: %d\n",
1105                        dev, tty->count);
1106                 tty->count = 0;
1107         }
1108         if (tty->count)
1109                 return;
1110 
1111         /*
1112          * Make sure there aren't any processes that still think this
1113          * tty is their controlling tty.
1114          */
1115         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1116                 if ((*p) && (*p)->tty == tty->line)
1117                 (*p)->tty = -1;
1118         }
1119 
1120         if (ldiscs[tty->disc].close != NULL)
1121                 ldiscs[tty->disc].close(tty);
1122 
1123         if (o_tty) {
1124                 if (o_tty->count)
1125                         return;
1126                 else {
1127                         tty_table[PTY_OTHER(dev)] = NULL;
1128                         tty_termios[PTY_OTHER(dev)] = NULL;
1129                 }
1130         }
1131         tty_table[dev] = NULL;
1132         if (IS_A_PTY(dev)) {
1133                 tty_termios[dev] = NULL;
1134                 kfree_s(tp, sizeof(struct termios));
1135         }
1136         if (tty == redirect || o_tty == redirect)
1137                 redirect = NULL;
1138         free_page((unsigned long) tty);
1139         if (o_tty)
1140                 free_page((unsigned long) o_tty);
1141         if (o_tp)
1142                 kfree_s(o_tp, sizeof(struct termios));
1143 }
1144 
1145 /*
1146  * tty_open and tty_release keep up the tty count that contains the
1147  * number of opens done on a tty. We cannot use the inode-count, as
1148  * different inodes might point to the same tty.
1149  *
1150  * Open-counting is needed for pty masters, as well as for keeping
1151  * track of serial lines: DTR is dropped when the last close happens.
1152  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1153  *
1154  * The termios state of a pty is reset on first open so that
1155  * settings don't persist across reuse.
1156  */
1157 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1158 {
1159         struct tty_struct *tty;
1160         int major, minor;
1161         int noctty, retval;
1162 
1163         minor = MINOR(inode->i_rdev);
1164         major = MAJOR(inode->i_rdev);
1165         noctty = filp->f_flags & O_NOCTTY;
1166         if (major == 5) {
1167                 if (!minor) {
1168                         major = 4;
1169                         minor = current->tty;
1170                 }
1171                 noctty = 1;
1172         } else if (major == 4) {
1173                 if (!minor) {
1174                         minor = fg_console + 1;
1175                         noctty = 1;
1176                 }
1177         } else {
1178                 printk("Bad major #%d in tty_open\n", MAJOR(inode->i_rdev));
1179                 return -ENODEV;
1180         }
1181         if (minor <= 0)
1182                 return -ENXIO;
1183         if (IS_A_PTY_MASTER(minor))
1184                 noctty = 1;
1185         filp->f_rdev = (major << 8) | minor;
1186         retval = init_dev(minor);
1187         if (retval)
1188                 return retval;
1189         tty = tty_table[minor];
1190 
1191         /* clean up the packet stuff. */
1192         /*
1193          *  Why is this not done in init_dev?  Right here, if another 
1194          * process opens up a tty in packet mode, all the packet 
1195          * variables get cleared.  Come to think of it, is anything 
1196          * using the packet mode at all???  - Ted, 1/27/93
1197          */
1198         tty->status_changed = 0;
1199         tty->ctrl_status = 0;
1200         tty->packet = 0;
1201 
1202         if (tty->open) {
1203                 retval = tty->open(tty, filp);
1204         } else {
1205                 retval = -ENODEV;
1206         }
1207         if (retval) {
1208                 release_dev(minor, filp);
1209                 return retval;
1210         }
1211         if (!noctty &&
1212             current->leader &&
1213             current->tty<0 &&
1214             tty->session==0) {
1215                 current->tty = minor;
1216                 tty->session = current->session;
1217                 tty->pgrp = current->pgrp;
1218         }
1219         filp->f_rdev = 0x0400 | minor; /* Set it to something normal */
1220         return 0;
1221 }
1222 
1223 /*
1224  * Note that releasing a pty master also releases the child, so
1225  * we have to make the redirection checks after that and on both
1226  * sides of a pty.
1227  */
1228 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1229 {
1230         int dev;
1231 
1232         dev = filp->f_rdev;
1233         if (MAJOR(dev) != 4) {
1234                 printk("tty_release: tty pseudo-major != 4\n");
1235                 return;
1236         }
1237         dev = MINOR(filp->f_rdev);
1238         if (!dev) {
1239                 printk("tty_release: bad f_rdev\n");
1240                 return;
1241         }
1242         release_dev(dev, filp);
1243 }
1244 
1245 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1246 {
1247         int dev;
1248         struct tty_struct * tty;
1249 
1250         dev = filp->f_rdev;
1251         if (MAJOR(dev) != 4) {
1252                 printk("tty_select: tty pseudo-major != 4\n");
1253                 return 0;
1254         }
1255         dev = MINOR(filp->f_rdev);
1256         tty = TTY_TABLE(dev);
1257         if (!tty) {
1258                 printk("tty_select: tty struct for dev %d was NULL\n", dev);
1259                 return 0;
1260         }
1261         switch (sel_type) {
1262                 case SEL_IN:
1263                         if (L_CANON(tty)) {
1264                                 if (available_canon_input(tty))
1265                                         return 1;
1266                         } else if (!EMPTY(&tty->secondary))
1267                                 return 1;
1268                         if (tty->link && !tty->link->count)
1269                                 return 1;
1270 
1271                         /* see if the status byte can be read. */
1272                         if (tty->packet && tty->link &&
1273                             tty->link->status_changed)
1274                                 return 1;
1275 
1276                         select_wait(&tty->secondary.proc_list, wait);
1277                         return 0;
1278                 case SEL_OUT:
1279                         if (!FULL(&tty->write_q))
1280                                 return 1;
1281                         select_wait(&tty->write_q.proc_list, wait);
1282                         return 0;
1283                 case SEL_EX:
1284                         if (tty->link && !tty->link->count)
1285                                 return 1;
1286                         return 0;
1287         }
1288         return 0;
1289 }
1290 
1291 /*
1292  * This implements the "Secure Attention Key" ---  the idea is to
1293  * prevent trojan horses by killing all processes associated with this
1294  * tty when the user hits the "Secure Attention Key".  Required for
1295  * super-paranoid applications --- see the Orange Book for more details.
1296  * 
1297  * This code could be nicer; ideally it should send a HUP, wait a few
1298  * seconds, then send a INT, and then a KILL signal.  But you then
1299  * have to coordinate with the init process, since all processes associated
1300  * with the current tty must be dead before the new getty is allowed
1301  * to spawn.
1302  */
1303 void do_SAK( struct tty_struct *tty)
     /*  */
1304 {
1305         struct task_struct **p;
1306         int line = tty->line;
1307         int session = tty->session;
1308         int             i;
1309         struct file     *filp;
1310         
1311         flush_input(tty);
1312         flush_output(tty);
1313         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1314                 if (!(*p))
1315                         continue;
1316                 if (((*p)->tty == line) ||
1317                     ((session > 0) && ((*p)->session == session)))
1318                         send_sig(SIGKILL, *p, 1);
1319                 else {
1320                         for (i=0; i < NR_FILE; i++) {
1321                                 filp = (*p)->filp[i];
1322                                 if (filp && (filp->f_op == &tty_fops) &&
1323                                     (MINOR(filp->f_rdev) == line)) {
1324                                         send_sig(SIGKILL, *p, 1);
1325                                         break;
1326                                 }
1327                         }
1328                 }
1329         }
1330 }
1331 
1332 /*
1333  * This routine allows a kernel routine to send a large chunk of data
1334  * to a particular tty; if all of the data can be queued up for ouput
1335  * immediately, tty_write_data() will return 0.  If, however, not all
1336  * of the data can be immediately queued for delivery, the number of
1337  * bytes left to be queued up will be returned, and the rest of the
1338  * data will be queued up when there is room.  The callback function
1339  * will be called (with the argument callarg) when the last of the
1340  * data is finally in the queue.
1341  *
1342  * Note that the callback routine will _not_ be called if all of the
1343  * data could be queued immediately.  This is to avoid a problem with
1344  * the kernel stack getting too deep, which might happen if the
1345  * callback routine calls tty_write_data with itself as an argument.
1346  */
1347 int tty_write_data(struct tty_struct *tty, char *bufp, int buflen,
     /*  */
1348                     void (*callback)(void * data), void * callarg)
1349 {
1350         int head, tail, count;
1351         unsigned long flags;
1352         char *p;
1353 
1354 #define VLEFT ((tail-head-1)&(TTY_BUF_SIZE-1))
1355 
1356         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
1357         if (tty->write_data_cnt) {
1358                 __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1359                 return -EBUSY;
1360         }
1361 
1362         head = tty->write_q.head;
1363         tail = tty->write_q.tail;
1364         count = buflen;
1365         p = bufp;
1366 
1367         while (count && VLEFT > 0) {
1368                 tty->write_q.buf[head++] = *p++;
1369                 head &= TTY_BUF_SIZE-1;
1370         }
1371         tty->write_q.head = head;
1372         if (count) {
1373                 tty->write_data_cnt = count;
1374                 tty->write_data_ptr = p;
1375                 tty->write_data_callback = callback;
1376                 tty->write_data_arg = callarg;
1377         }
1378         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1379         return count;
1380 }
1381 
1382 /*
1383  * This routine routine is called after an interrupt has drained a
1384  * tty's write queue, so that there is more space for data waiting to
1385  * be sent in tty->write_data_ptr.
1386  *
1387  * tty_check_write[8] is a bitstring which indicates which ttys
1388  * needs to be processed.
1389  */
1390 void tty_bh_routine(void * unused)
     /*  */
1391 {
1392         int     i, j, line, mask;
1393         int     head, tail, count;
1394         unsigned char * p;
1395         struct tty_struct * tty;
1396 
1397         for (i = 0, line = 0; i < MAX_TTYS / 32; i++) {
1398                 if (!tty_check_write[i]) {
1399                         line += 32;
1400                         continue;
1401                 }
1402                 for (j=0, mask=0; j < 32; j++, line++, mask <<= 1) {
1403                         if (!clear_bit(j, &tty_check_write[i])) {
1404                                 tty = tty_table[line];
1405                                 if (!tty || !tty->write_data_cnt)
1406                                         continue;
1407                                 cli();
1408                                 head = tty->write_q.head;
1409                                 tail = tty->write_q.tail;
1410                                 count = tty->write_data_cnt;
1411                                 p = tty->write_data_ptr;
1412 
1413                                 while (count && VLEFT > 0) {
1414                                         tty->write_q.buf[head++] = *p++;
1415                                         head &= TTY_BUF_SIZE-1;
1416                                 }
1417                                 tty->write_q.head = head;
1418                                 tty->write_data_ptr = p;
1419                                 tty->write_data_cnt = count;
1420                                 sti();
1421                                 if (!count)
1422                                         (tty->write_data_callback)
1423                                                 (tty->write_data_arg);
1424                         }
1425                 }
1426         }
1427         
1428 }
1429 
1430 /*
1431  * This subroutine initializes a tty structure.  We have to set up
1432  * things correctly for each different type of tty.
1433  */
1434 static void initialize_tty_struct(int line, struct tty_struct *tty)
     /*  */
1435 {
1436         memset(tty, 0, sizeof(struct tty_struct));
1437         tty->line = line;
1438         tty->disc = N_TTY;
1439         tty->pgrp = -1;
1440         tty->winsize.ws_row = 0;
1441         tty->winsize.ws_col = 0;
1442         if (IS_A_CONSOLE(line)) {
1443                 tty->open = con_open;
1444                 tty->winsize.ws_row = video_num_lines;
1445                 tty->winsize.ws_col = video_num_columns;
1446         } else if IS_A_SERIAL(line) {
1447                 tty->open = rs_open;
1448         } else if IS_A_PTY(line) {
1449                 tty->open = pty_open;
1450         }
1451 }
1452 
1453 static void initialize_termios(int line, struct termios * tp)
     /*  */
1454 {
1455         memset(tp, 0, sizeof(struct termios));
1456         memcpy(tp->c_cc, INIT_C_CC, NCCS);
1457         if (IS_A_CONSOLE(line)) {
1458                 tp->c_iflag = ICRNL | IXON;
1459                 tp->c_oflag = OPOST | ONLCR;
1460                 tp->c_cflag = B38400 | CS8 | CREAD;
1461                 tp->c_lflag = ISIG | ICANON | ECHO |
1462                         ECHOCTL | ECHOKE;
1463         } else if (IS_A_SERIAL(line)) {
1464                 tp->c_cflag = B2400 | CS8 | CREAD | HUPCL | CLOCAL;
1465         } else if (IS_A_PTY_MASTER(line)) {
1466                 tp->c_cflag = B9600 | CS8 | CREAD;
1467         } else if (IS_A_PTY_SLAVE(line)) {
1468                 tp->c_iflag = ICRNL | IXON;
1469                 tp->c_oflag = OPOST | ONLCR;
1470                 tp->c_cflag = B38400 | CS8 | CREAD;
1471                 tp->c_lflag = ISIG | ICANON | ECHO |
1472                         ECHOCTL | ECHOKE;
1473         }
1474 }
1475 
1476 static struct tty_ldisc tty_ldisc_N_TTY = {
1477         0,                      /* flags */
1478         NULL,                   /* open */
1479         NULL,                   /* close */
1480         read_chan,              /* read */
1481         write_chan,             /* write */
1482         NULL,                   /* ioctl */
1483         copy_to_cooked          /* handler */
1484 };
1485 
1486         
1487 long tty_init(long kmem_start)
     /*  */
1488 {
1489         int i;
1490 
1491         if (sizeof(struct tty_struct) > 4096)
1492                 panic("size of tty structure > 4096!");
1493         if (register_chrdev(4,"tty",&tty_fops))
1494                 panic("unable to get major 4 for tty device");
1495         if (register_chrdev(5,"tty",&tty_fops))
1496                 panic("unable to get major 5 for tty device");
1497         for (i=0 ; i< MAX_TTYS ; i++) {
1498                 tty_table[i] =  0;
1499                 tty_termios[i] = 0;
1500         }
1501         memset(tty_check_write, 0, sizeof(tty_check_write));
1502         bh_base[TTY_BH].routine = tty_bh_routine;
1503 
1504         /* Setup the default TTY line discipline. */
1505         memset(ldiscs, 0, sizeof(ldiscs));
1506         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1507 
1508         kmem_start = kbd_init(kmem_start);
1509         kmem_start = con_init(kmem_start);
1510         kmem_start = rs_init(kmem_start);
1511         return kmem_start;
1512 }
/* */
root/kernel/chr_drv/tty_io.c

DEFINITIONS
