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_inode && filp->f_inode->i_rdev == 0x0400)
 247                         continue;
 248                 if (filp->f_op != &tty_fops)
 249                         continue;
 250                 filp->f_op = fops;
 251         }
 252         wake_up_interruptible(&tty->secondary.proc_list);
 253         wake_up_interruptible(&tty->read_q.proc_list);
 254         wake_up_interruptible(&tty->write_q.proc_list);
 255         if (tty->session > 0)
 256                 kill_sl(tty->session,SIGHUP,1);
 257         tty->session = 0;
 258         tty->pgrp = -1;
 259         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
 260                 if ((*p) && (*p)->tty == tty->line)
 261                         (*p)->tty = -1;
 262         }
 263 }
 264 
 265 void tty_hangup(struct tty_struct * tty)
     /*  */
 266 {
 267         do_tty_hangup(tty, &hung_up_tty_fops);
 268 }
 269 
 270 void tty_vhangup(struct tty_struct * tty)
     /*  */
 271 {
 272         do_tty_hangup(tty, &vhung_up_tty_fops);
 273 }
 274 
 275 void tty_unhangup(struct file *filp)
     /*  */
 276 {
 277         filp->f_op = &tty_fops;
 278 }
 279 
 280 inline int tty_hung_up_p(struct file * filp)
     /*  */
 281 {
 282         return ((filp->f_op == &hung_up_tty_fops) ||
 283                 (filp->f_op == &vhung_up_tty_fops));
 284 }
 285 
 286 /*
 287  * Sometimes we want to wait until a particular VT has been activated. We
 288  * do it in a very simple manner. Everybody waits on a single queue and
 289  * get woken up at once. Those that are satisfied go on with their business,
 290  * while those not ready go back to sleep. Seems overkill to add a wait
 291  * to each vt just for this - usually this does nothing!
 292  */
 293 static struct wait_queue *vt_activate_queue = NULL;
 294 
 295 /*
 296  * Sleeps until a vt is activated, or the task is interrupted. Returns
 297  * 0 if activation, -1 if interrupted.
 298  */
 299 int vt_waitactive(void)
     /*  */
 300 {
 301         interruptible_sleep_on(&vt_activate_queue);
 302         return (current->signal & ~current->blocked) ? -1 : 0;
 303 }
 304 
 305 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 306 
 307 extern int kill_proc(int pid, int sig, int priv);
 308 
 309 /*
 310  * Performs the back end of a vt switch
 311  */
 312 void complete_change_console(unsigned int new_console)
     /*  */
 313 {
 314         unsigned char old_vc_mode;
 315 
 316         if (new_console == fg_console || new_console >= NR_CONSOLES)
 317                 return;
 318 
 319         /*
 320          * If we're switching, we could be going from KD_GRAPHICS to
 321          * KD_TEXT mode or vice versa, which means we need to blank or
 322          * unblank the screen later.
 323          */
 324         old_vc_mode = vt_cons[fg_console].vc_mode;
 325         update_screen(new_console);
 326 
 327         /*
 328          * If this new console is under process control, send it a signal
 329          * telling it that it has acquired. Also check if it has died and
 330          * clean up (similar to logic employed in change_console())
 331          */
 332         if (vt_cons[new_console].vt_mode.mode == VT_PROCESS)
 333         {
 334                 /*
 335                  * Send the signal as privileged - kill_proc() will
 336                  * tell us if the process has gone or something else
 337                  * is awry
 338                  */
 339                 if (kill_proc(vt_cons[new_console].vt_pid,
 340                               vt_cons[new_console].vt_mode.acqsig,
 341                               1) != 0)
 342                 {
 343                 /*
 344                  * The controlling process has died, so we revert back to
 345                  * normal operation. In this case, we'll also change back
 346                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 347                  * but it saves the agony when the X server dies and the screen
 348                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 349                  * this outside of VT_PROCESS but there is no single process
 350                  * to account for and tracking tty count may be undesirable.
 351                  */
 352                         vt_cons[new_console].vc_mode = KD_TEXT;
 353                         clr_vc_kbd_flag(kbd_table + new_console, VC_RAW);
 354                         vt_cons[new_console].vt_mode.mode = VT_AUTO;
 355                         vt_cons[new_console].vt_mode.waitv = 0;
 356                         vt_cons[new_console].vt_mode.relsig = 0;
 357                         vt_cons[new_console].vt_mode.acqsig = 0;
 358                         vt_cons[new_console].vt_mode.frsig = 0;
 359                         vt_cons[new_console].vt_pid = -1;
 360                         vt_cons[new_console].vt_newvt = -1;
 361                 }
 362         }
 363 
 364         /*
 365          * We do this here because the controlling process above may have
 366          * gone, and so there is now a new vc_mode
 367          */
 368         if (old_vc_mode != vt_cons[new_console].vc_mode)
 369         {
 370                 if (vt_cons[new_console].vc_mode == KD_TEXT)
 371                         unblank_screen();
 372                 else
 373                 {
 374                         timer_active &= ~(1<<BLANK_TIMER);
 375                         blank_screen();
 376                 }
 377         }
 378 
 379         /*
 380          * Wake anyone waiting for their VT to activate
 381          */
 382         vt_wake_waitactive();
 383         return;
 384 }
 385 
 386 /*
 387  * Performs the front-end of a vt switch
 388  */
 389 void change_console(unsigned int new_console)
     /*  */
 390 {
 391         if (new_console == fg_console || new_console >= NR_CONSOLES)
 392                 return;
 393 
 394         /*
 395          * If this vt is in process mode, then we need to handshake with
 396          * that process before switching. Essentially, we store where that
 397          * vt wants to switch to and wait for it to tell us when it's done
 398          * (via VT_RELDISP ioctl).
 399          *
 400          * We also check to see if the controlling process still exists.
 401          * If it doesn't, we reset this vt to auto mode and continue.
 402          * This is a cheap way to track process control. The worst thing
 403          * that can happen is: we send a signal to a process, it dies, and
 404          * the switch gets "lost" waiting for a response; hopefully, the
 405          * user will try again, we'll detect the process is gone (unless
 406          * the user waits just the right amount of time :-) and revert the
 407          * vt to auto control.
 408          */
 409         if (vt_cons[fg_console].vt_mode.mode == VT_PROCESS)
 410         {
 411                 /*
 412                  * Send the signal as privileged - kill_proc() will
 413                  * tell us if the process has gone or something else
 414                  * is awry
 415                  */
 416                 if (kill_proc(vt_cons[fg_console].vt_pid,
 417                               vt_cons[fg_console].vt_mode.relsig,
 418                               1) == 0)
 419                 {
 420                         /*
 421                          * It worked. Mark the vt to switch to and
 422                          * return. The process needs to send us a
 423                          * VT_RELDISP ioctl to complete the switch.
 424                          */
 425                         vt_cons[fg_console].vt_newvt = new_console;
 426                         return;
 427                 }
 428 
 429                 /*
 430                  * The controlling process has died, so we revert back to
 431                  * normal operation. In this case, we'll also change back
 432                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 433                  * but it saves the agony when the X server dies and the screen
 434                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 435                  * this outside of VT_PROCESS but there is no single process
 436                  * to account for and tracking tty count may be undesirable.
 437                  */
 438                 vt_cons[fg_console].vc_mode = KD_TEXT;
 439                 clr_vc_kbd_flag(kbd_table + fg_console, VC_RAW);
 440                 vt_cons[fg_console].vt_mode.mode = VT_AUTO;
 441                 vt_cons[fg_console].vt_mode.waitv = 0;
 442                 vt_cons[fg_console].vt_mode.relsig = 0;
 443                 vt_cons[fg_console].vt_mode.acqsig = 0;
 444                 vt_cons[fg_console].vt_mode.frsig = 0;
 445                 vt_cons[fg_console].vt_pid = -1;
 446                 vt_cons[fg_console].vt_newvt = -1;
 447                 /*
 448                  * Fall through to normal (VT_AUTO) handling of the switch...
 449                  */
 450         }
 451 
 452         /*
 453          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 454          */
 455         if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
 456                 return;
 457 
 458         complete_change_console(new_console);
 459 }
 460 
 461 void wait_for_keypress(void)
     /*  */
 462 {
 463         sleep_on(&keypress_wait);
 464 }
 465 
 466 void copy_to_cooked(struct tty_struct * tty)
     /*  */
 467 {
 468         int c, special_flag;
 469         unsigned long flags;
 470 
 471         if (!tty) {
 472                 printk("copy_to_cooked: called with NULL tty\n");
 473                 return;
 474         }
 475         if (!tty->write) {
 476                 printk("copy_to_cooked: tty %d has null write routine\n",
 477                        tty->line);
 478         }
 479         while (1) {
 480                 /*
 481                  * Check to see how much room we have left in the
 482                  * secondary queue.  Send a throttle command or abort
 483                  * if necessary.
 484                  */
 485                 c = LEFT(&tty->secondary);
 486                 if (tty->throttle && (c < SQ_THRESHOLD_LW)
 487                     && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
 488                         tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
 489                 if (c == 0)
 490                         break;
 491                 save_flags(flags); cli();
 492                 if (tty->read_q.tail != tty->read_q.head) {
 493                         c = 0xff & tty->read_q.buf[tty->read_q.tail];
 494                         special_flag = !clear_bit(tty->read_q.tail,
 495                                                   &tty->readq_flags);
 496                         tty->read_q.tail = (tty->read_q.tail + 1) &
 497                                 (TTY_BUF_SIZE-1);
 498                         restore_flags(flags);
 499                 } else {
 500                         restore_flags(flags);
 501                         break;
 502                 }
 503                 if (special_flag) {
 504                         tty->char_error = c & 3;
 505                         continue;
 506                 }
 507                 if (tty->char_error) {
 508                         if (tty->char_error == TTY_BREAK) {
 509                                 tty->char_error = 0;
 510                                 if (I_IGNBRK(tty))
 511                                         continue;
 512                                 if (I_PARMRK(tty)) {
 513                                         put_tty_queue(0377, &tty->secondary);
 514                                         put_tty_queue(0, &tty->secondary);
 515                                 }
 516                                 put_tty_queue(0, &tty->secondary);
 517                                 continue;
 518                         }
 519                         /* If not a break, then a parity or frame error */
 520                         tty->char_error = 0;
 521                         if (I_IGNPAR(tty)) {
 522                                 continue;
 523                         }
 524                         if (I_PARMRK(tty)) {
 525                                 put_tty_queue(0377, &tty->secondary);
 526                                 put_tty_queue(0, &tty->secondary);
 527                                 put_tty_queue(c, &tty->secondary);
 528                         } else
 529                                 put_tty_queue(0, &tty->secondary);
 530                         continue;
 531                 }
 532                 if (I_STRP(tty))
 533                         c &= 0x7f;
 534                 else if (I_PARMRK(tty) && (c == 0377))
 535                         put_tty_queue(0377, &tty->secondary);
 536                 if (c==13) {
 537                         if (I_CRNL(tty))
 538                                 c=10;
 539                         else if (I_NOCR(tty))
 540                                 continue;
 541                 } else if (c==10 && I_NLCR(tty))
 542                         c=13;
 543                 if (I_UCLC(tty))
 544                         c=tolower(c);
 545                 if (c == __DISABLED_CHAR)
 546                         tty->lnext = 1;
 547                 if (L_CANON(tty) && !tty->lnext) {
 548                         if (c == KILL_CHAR(tty)) {
 549                                 /* deal with killing the input line */
 550                                 while(!(EMPTY(&tty->secondary) ||
 551                                         (c=LAST(&tty->secondary))==10 ||
 552                                         ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 553                                          (c==EOF_CHAR(tty))))) {
 554                                         if (L_ECHO(tty)) {
 555                                                 if (c<32) {
 556                                                         put_tty_queue(8, &tty->write_q);
 557                                                         put_tty_queue(' ', &tty->write_q);
 558                                                         put_tty_queue(8,&tty->write_q);
 559                                                 }
 560                                                 put_tty_queue(8,&tty->write_q);
 561                                                 put_tty_queue(' ',&tty->write_q);
 562                                                 put_tty_queue(8,&tty->write_q);
 563                                         }
 564                                         DEC(tty->secondary.head);
 565                                 }
 566                                 continue;
 567                         }
 568                         if (c == ERASE_CHAR(tty)) {
 569                                 if (EMPTY(&tty->secondary) ||
 570                                    (c=LAST(&tty->secondary))==10 ||
 571                                    ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 572                                     (c==EOF_CHAR(tty))))
 573                                         continue;
 574                                 if (L_ECHO(tty)) {
 575                                         if (c<32) {
 576                                                 put_tty_queue(8,&tty->write_q);
 577                                                 put_tty_queue(' ',&tty->write_q);
 578                                                 put_tty_queue(8,&tty->write_q);
 579                                         }
 580                                         put_tty_queue(8,&tty->write_q);
 581                                         put_tty_queue(32,&tty->write_q);
 582                                         put_tty_queue(8,&tty->write_q);
 583                                 }
 584                                 DEC(tty->secondary.head);
 585                                 continue;
 586                         }
 587                         if (c == LNEXT_CHAR(tty)) {
 588                                 tty->lnext = 1;
 589                                 if (L_ECHO(tty)) {
 590                                         put_tty_queue('^',&tty->write_q);
 591                                         put_tty_queue(8,&tty->write_q);
 592                                 }
 593                                 continue;
 594                         }
 595                 }
 596                 if (I_IXON(tty) && !tty->lnext) {
 597                         if (c == STOP_CHAR(tty)) {
 598                                 tty->status_changed = 1;
 599                                 tty->ctrl_status |= TIOCPKT_STOP;
 600                                 tty->stopped=1;
 601                                 continue;
 602                         }
 603                         if (((I_IXANY(tty)) && tty->stopped) ||
 604                             (c == START_CHAR(tty))) {
 605                                 tty->status_changed = 1;
 606                                 tty->ctrl_status |= TIOCPKT_START;
 607                                 tty->stopped=0;
 608                                 continue;
 609                         }
 610                 }
 611                 if (L_ISIG(tty) && !tty->lnext) {
 612                         if (c == INTR_CHAR(tty)) {
 613                                 kill_pg(tty->pgrp, SIGINT, 1);
 614                                 flush_input(tty);
 615                                 continue;
 616                         }
 617                         if (c == QUIT_CHAR(tty)) {
 618                                 kill_pg(tty->pgrp, SIGQUIT, 1);
 619                                 flush_input(tty);
 620                                 continue;
 621                         }
 622                         if (c == SUSPEND_CHAR(tty)) {
 623                                 if (!is_orphaned_pgrp(tty->pgrp))
 624                                         kill_pg(tty->pgrp, SIGTSTP, 1);
 625                                 continue;
 626                         }
 627                 }
 628                 if (c==10 || (EOF_CHAR(tty) != __DISABLED_CHAR &&
 629                     c==EOF_CHAR(tty)))
 630                         tty->secondary.data++;
 631                 if ((c==10) && (L_ECHO(tty) || (L_CANON(tty) && L_ECHONL(tty)))) {
 632                         put_tty_queue(10,&tty->write_q);
 633                         put_tty_queue(13,&tty->write_q);
 634                 } else if (L_ECHO(tty)) {
 635                         if (c<32 && L_ECHOCTL(tty)) {
 636                                 put_tty_queue('^',&tty->write_q);
 637                                 put_tty_queue(c+64, &tty->write_q);
 638                                 if (EOF_CHAR(tty) != __DISABLED_CHAR &&
 639                                     c==EOF_CHAR(tty) && !tty->lnext) {
 640                                         put_tty_queue(8,&tty->write_q);
 641                                         put_tty_queue(8,&tty->write_q);
 642                                 }
 643                         } else
 644                                 put_tty_queue(c, &tty->write_q);
 645                 }
 646                 tty->lnext = 0;
 647                 put_tty_queue(c, &tty->secondary);
 648         }
 649         TTY_WRITE_FLUSH(tty);
 650         if (!EMPTY(&tty->secondary))
 651                 wake_up_interruptible(&tty->secondary.proc_list);
 652         if (tty->write_q.proc_list && LEFT(&tty->write_q) > TTY_BUF_SIZE/2)
 653                 wake_up_interruptible(&tty->write_q.proc_list);
 654         if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
 655             && !clear_bit(TTY_RQ_THROTTLED, &tty->flags))
 656                 tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
 657         if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 658             && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 659                 tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 660 }
 661 
 662 int is_ignored(int sig)
     /*  */
 663 {
 664         return ((current->blocked & (1<<(sig-1))) ||
 665                 (current->sigaction[sig-1].sa_handler == SIG_IGN));
 666 }
 667 
 668 static int available_canon_input(struct tty_struct *);
 669 static void __wait_for_canon_input(struct file * file, struct tty_struct *);
 670 
 671 static void wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 672 {
 673         if (!available_canon_input(tty)) {
 674                 if (current->signal & ~current->blocked)
 675                         return;
 676                 __wait_for_canon_input(file, tty);
 677         }
 678 }
 679 
 680 static int read_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 681 {
 682         struct wait_queue wait = { current, NULL };
 683         int c;
 684         char * b=buf;
 685         int minimum,time;
 686 
 687         if (L_CANON(tty))
 688                 minimum = time = current->timeout = 0;
 689         else {
 690                 time = 10L*tty->termios->c_cc[VTIME];
 691                 minimum = tty->termios->c_cc[VMIN];
 692                 if (minimum)
 693                         current->timeout = 0xffffffff;
 694                 else {
 695                         if (time)
 696                                 current->timeout = time + jiffies;
 697                         else
 698                                 current->timeout = 0;
 699                         time = 0;
 700                         minimum = 1;
 701                 }
 702         }
 703         if (file->f_flags & O_NONBLOCK) {
 704                 time = current->timeout = 0;
 705                 if (L_CANON(tty)) {
 706                         if (!available_canon_input(tty))
 707                                 return -EAGAIN;
 708                 }
 709         } else if (L_CANON(tty)) {
 710                 wait_for_canon_input(file, tty);
 711                 if (current->signal & ~current->blocked)
 712                         return -ERESTARTSYS;
 713         }
 714         if (minimum>nr)
 715                 minimum = nr;
 716 
 717         /* deal with packet mode:  First test for status change */
 718         if (tty->packet && tty->link && tty->link->status_changed) {
 719                 put_fs_byte (tty->link->ctrl_status, b);
 720                 tty->link->status_changed = 0;
 721                 return 1;
 722         }
 723           
 724         /* now bump the buffer up one. */
 725         if (tty->packet) {
 726                 put_fs_byte (0,b++);
 727                 nr--;
 728                 /* this really shouldn't happen, but we need to 
 729                 put it here. */
 730                 if (nr == 0)
 731                         return 1;
 732         }
 733         add_wait_queue(&tty->secondary.proc_list, &wait);
 734         while (nr>0) {
 735                 if (tty_hung_up_p(file)) {
 736                         file->f_flags &= ~O_NONBLOCK;
 737                         break;  /* force read() to return 0 */
 738                 }
 739                 TTY_READ_FLUSH(tty);
 740                 if (tty->link)
 741                         TTY_WRITE_FLUSH(tty->link);
 742                 while (nr > 0 && ((c = get_tty_queue(&tty->secondary)) >= 0)) {
 743                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 744                              c==EOF_CHAR(tty)) || c==10)
 745                                 tty->secondary.data--;
 746                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 747                              c==EOF_CHAR(tty)) && L_CANON(tty))
 748                                 break;
 749                         put_fs_byte(c,b++);
 750                         nr--;
 751                         if (time)
 752                                 current->timeout = time+jiffies;
 753                         if (c==10 && L_CANON(tty))
 754                                 break;
 755                 };
 756                 wake_up_interruptible(&tty->read_q.proc_list);
 757                 /*
 758                  * If there is enough space in the secondary queue
 759                  * now, let the low-level driver know.
 760                  */
 761                 if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 762                     && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 763                         tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 764                 if (b-buf >= minimum || !current->timeout)
 765                         break;
 766                 if (current->signal & ~current->blocked) 
 767                         break;
 768                 if (tty->link && !tty->link->count)
 769                         break;
 770                 TTY_READ_FLUSH(tty);
 771                 if (tty->link)
 772                         TTY_WRITE_FLUSH(tty->link);
 773                 if (!EMPTY(&tty->secondary))
 774                         continue;
 775                 current->state = TASK_INTERRUPTIBLE;
 776                 if (EMPTY(&tty->secondary))
 777                         schedule();
 778                 current->state = TASK_RUNNING;
 779         }
 780         remove_wait_queue(&tty->secondary.proc_list, &wait);
 781         TTY_READ_FLUSH(tty);
 782         if (tty->link && tty->link->write)
 783                 TTY_WRITE_FLUSH(tty->link);
 784         current->timeout = 0;
 785 
 786         /* packet mode sticks in an extra 0.  If that's all we've got,
 787            we should count it a zero bytes. */
 788         if (tty->packet) {
 789                 if ((b-buf) > 1)
 790                         return b-buf;
 791         } else {
 792                 if (b-buf)
 793                         return b-buf;
 794         }
 795 
 796         if (current->signal & ~current->blocked)
 797                 return -ERESTARTSYS;
 798         if (file->f_flags & O_NONBLOCK)
 799                 return -EAGAIN;
 800         return 0;
 801 }
 802 
 803 static void __wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 804 {
 805         struct wait_queue wait = { current, NULL };
 806 
 807         add_wait_queue(&tty->secondary.proc_list, &wait);
 808         while (1) {
 809                 current->state = TASK_INTERRUPTIBLE;
 810                 if (available_canon_input(tty))
 811                         break;
 812                 if (current->signal & ~current->blocked)
 813                         break;
 814                 if (tty_hung_up_p(file))
 815                         break;
 816                 schedule();
 817         }
 818         current->state = TASK_RUNNING;
 819         remove_wait_queue(&tty->secondary.proc_list, &wait);
 820 }
 821 
 822 static int available_canon_input(struct tty_struct * tty)
     /*  */
 823 {
 824         TTY_READ_FLUSH(tty);
 825         if (tty->link)
 826                 if (tty->link->count)
 827                         TTY_WRITE_FLUSH(tty->link);
 828                 else
 829                         return 1;
 830         if (FULL(&tty->read_q))
 831                 return 1;
 832         if (tty->secondary.data)
 833                 return 1;
 834         return 0;
 835 }
 836 
 837 static int write_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 838 {
 839         struct wait_queue wait = { current, NULL };
 840         char c, *b=buf;
 841 
 842         if (nr < 0)
 843                 return -EINVAL;
 844         if (!nr)
 845                 return 0;
 846         add_wait_queue(&tty->write_q.proc_list, &wait);
 847         while (nr>0) {
 848                 if (current->signal & ~current->blocked)
 849                         break;
 850                 if (tty_hung_up_p(file))
 851                         break;
 852                 if (tty->link && !tty->link->count) {
 853                         send_sig(SIGPIPE,current,0);
 854                         break;
 855                 }
 856                 current->state = TASK_INTERRUPTIBLE;
 857                 if (FULL(&tty->write_q)) {
 858                         TTY_WRITE_FLUSH(tty);
 859                         if (FULL(&tty->write_q))
 860                                 schedule();
 861                         current->state = TASK_RUNNING;
 862                         continue;
 863                 }
 864                 current->state = TASK_RUNNING;
 865                 while (nr>0 && !FULL(&tty->write_q)) {
 866                         c=get_fs_byte(b);
 867                         if (O_POST(tty)) {
 868                                 if (c=='\r' && O_CRNL(tty))
 869                                         c='\n';
 870                                 else if (c=='\n' && O_NLRET(tty))
 871                                         c='\r';
 872                                 if (c=='\n' && O_NLCR(tty) &&
 873                                     !set_bit(TTY_CR_PENDING,&tty->flags)) {
 874                                         put_tty_queue(13,&tty->write_q);
 875                                         continue;
 876                                 }
 877                                 if (O_LCUC(tty))
 878                                         c=toupper(c);
 879                         }
 880                         b++; nr--;
 881                         clear_bit(TTY_CR_PENDING,&tty->flags);
 882                         put_tty_queue(c,&tty->write_q);
 883                 }
 884                 if (need_resched)
 885                         schedule();
 886         }
 887         remove_wait_queue(&tty->write_q.proc_list, &wait);
 888         TTY_WRITE_FLUSH(tty);
 889         if (b-buf)
 890                 return b-buf;
 891         if (tty->link && !tty->link->count)
 892                 return -EPIPE;
 893         if (current->signal & ~current->blocked)
 894                 return -ERESTARTSYS;
 895         return 0;
 896 }
 897 
 898 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 899 {
 900         int i, dev;
 901         struct tty_struct * tty;
 902 
 903         dev = file->f_rdev;
 904         if (MAJOR(dev) != 4) {
 905                 printk("tty_read: bad pseudo-major nr #%d\n", MAJOR(dev));
 906                 return -EINVAL;
 907         }
 908         dev = MINOR(dev);
 909         tty = TTY_TABLE(dev);
 910         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 911                 return -EIO;
 912         if ((inode->i_rdev != 0x0400) && /* don't stop on /dev/console */
 913             (tty->pgrp > 0) &&
 914             (current->tty == dev) &&
 915             (tty->pgrp != current->pgrp))
 916                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 917                         return -EIO;
 918                 else {
 919                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 920                         return -ERESTARTSYS;
 921                 }
 922         if (ldiscs[tty->disc].read)
 923                 i = (ldiscs[tty->disc].read)(tty,file,buf,count);
 924         else
 925                 i = -EIO;
 926         if (i > 0)
 927                 inode->i_atime = CURRENT_TIME;
 928         return i;
 929 }
 930 
 931 static int tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 932 {
 933         int dev, i, is_console;
 934         struct tty_struct * tty;
 935 
 936         dev = file->f_rdev;
 937         is_console = (inode->i_rdev == 0x0400);
 938         if (MAJOR(dev) != 4) {
 939                 printk("tty_write: pseudo-major != 4\n");
 940                 return -EINVAL;
 941         }
 942         dev = MINOR(dev);
 943         if (is_console && redirect)
 944                 tty = redirect;
 945         else
 946                 tty = TTY_TABLE(dev);
 947         if (!tty || !tty->write || (tty->flags & (1 << TTY_IO_ERROR)))
 948                 return -EIO;
 949         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
 950             (current->tty == dev) && (tty->pgrp != current->pgrp)) {
 951                 if (is_orphaned_pgrp(current->pgrp))
 952                         return -EIO;
 953                 if (!is_ignored(SIGTTOU)) {
 954                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
 955                         return -ERESTARTSYS;
 956                 }
 957         }
 958         if (ldiscs[tty->disc].write)
 959                 i = (ldiscs[tty->disc].write)(tty,file,buf,count);
 960         else
 961                 i = -EIO;
 962         if (i > 0)
 963                 inode->i_mtime = CURRENT_TIME;
 964         return i;
 965 }
 966 
 967 /*
 968  * This is so ripe with races that you should *really* not touch this
 969  * unless you know exactly what you are doing. All the changes have to be
 970  * made atomically, or there may be incorrect pointers all over the place.
 971  */
 972 static int init_dev(int dev)
     /*  */
 973 {
 974         struct tty_struct *tty, *o_tty;
 975         struct termios *tp, *o_tp;
 976         int retval;
 977         int o_dev;
 978 
 979         o_dev = PTY_OTHER(dev);
 980         tty = o_tty = NULL;
 981         tp = o_tp = NULL;
 982 repeat:
 983         retval = -EAGAIN;
 984         if (IS_A_PTY_MASTER(dev) && tty_table[dev] && tty_table[dev]->count)
 985                 goto end_init;
 986         retval = -ENOMEM;
 987         if (!tty_table[dev] && !tty) {
 988                 tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
 989                 if (!tty)
 990                         goto end_init;
 991                 initialize_tty_struct(dev, tty);
 992                 goto repeat;
 993         }
 994         if (!tty_termios[dev] && !tp) {
 995                 tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
 996                 if (!tp)
 997                         goto end_init;
 998                 initialize_termios(dev, tp);
 999                 goto repeat;
1000         }
1001         if (IS_A_PTY(dev)) {
1002                 if (!tty_table[o_dev] && !o_tty) {
1003                         o_tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
1004                         if (!o_tty)
1005                                 goto end_init;
1006                         initialize_tty_struct(o_dev, o_tty);
1007                         goto repeat;
1008                 }
1009                 if (!tty_termios[o_dev] && !o_tp) {
1010                         o_tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
1011                         if (!o_tp)
1012                                 goto end_init;
1013                         initialize_termios(o_dev, o_tp);
1014                         goto repeat;
1015                 }
1016         }
1017         /* Now we have allocated all the structures: update all the pointers.. */
1018         if (!tty_termios[dev]) {
1019                 tty_termios[dev] = tp;
1020                 tp = NULL;
1021         }
1022         if (!tty_table[dev]) {
1023                 tty->termios = tty_termios[dev];
1024                 tty_table[dev] = tty;
1025                 tty = NULL;
1026         }
1027         if (IS_A_PTY(dev)) {
1028                 if (!tty_termios[o_dev]) {
1029                         tty_termios[o_dev] = o_tp;
1030                         o_tp = NULL;
1031                 }
1032                 if (!tty_table[o_dev]) {
1033                         o_tty->termios = tty_termios[o_dev];
1034                         tty_table[o_dev] = o_tty;
1035                         o_tty = NULL;
1036                 }
1037                 tty_table[dev]->link = tty_table[o_dev];
1038                 tty_table[o_dev]->link = tty_table[dev];
1039         }
1040         tty_table[dev]->count++;
1041         if (IS_A_PTY_MASTER(dev))
1042                 tty_table[o_dev]->count++;
1043         retval = 0;
1044 end_init:
1045         if (tty)
1046                 free_page((unsigned long) tty);
1047         if (o_tty)
1048                 free_page((unsigned long) tty);
1049         if (tp)
1050                 kfree_s(tp, sizeof(struct termios));
1051         if (o_tp)
1052                 kfree_s(o_tp, sizeof(struct termios));
1053         return retval;
1054 }
1055 
1056 /*
1057  * Even releasing the tty structures is a tricky business.. We have
1058  * to be very careful that the structures are all released at the
1059  * same time, as interrupts might otherwise get the wrong pointers.
1060  */
1061 static void release_dev(int dev, struct file * filp)
     /*  */
1062 {
1063         struct tty_struct *tty, *o_tty;
1064         struct termios *tp, *o_tp;
1065         struct task_struct **p;
1066 
1067         tty = tty_table[dev];
1068         tp = tty_termios[dev];
1069         o_tty = NULL;
1070         o_tp = NULL;
1071         if (!tty) {
1072                 printk("release_dev: tty_table[%d] was NULL\n", dev);
1073                 return;
1074         }
1075         if (!tp) {
1076                 printk("release_dev: tty_termios[%d] was NULL\n", dev);
1077                 return;
1078         }
1079         if (IS_A_PTY(dev)) {
1080                 o_tty = tty_table[PTY_OTHER(dev)];
1081                 o_tp = tty_termios[PTY_OTHER(dev)];
1082                 if (!o_tty) {
1083                         printk("release_dev: pty pair(%d) was NULL\n", dev);
1084                         return;
1085                 }
1086                 if (!o_tp) {
1087                         printk("release_dev: pty pair(%d) termios was NULL\n", dev);
1088                         return;
1089                 }
1090                 if (tty->link != o_tty || o_tty->link != tty) {
1091                         printk("release_dev: bad pty pointers\n");
1092                         return;
1093                 }
1094         }
1095         tty->write_data_cnt = 0; /* Clear out pending trash */
1096         if (tty->close)
1097                 tty->close(tty, filp);
1098         if (IS_A_PTY_MASTER(dev)) {
1099                 if (--tty->link->count < 0) {
1100                         printk("release_dev: bad tty slave count (dev = %d): %d\n",
1101                                dev, tty->count);
1102                         tty->link->count = 0;
1103                 }
1104         }
1105         if (--tty->count < 0) {
1106                 printk("release_dev: bad tty_table[%d]->count: %d\n",
1107                        dev, tty->count);
1108                 tty->count = 0;
1109         }
1110         if (tty->count)
1111                 return;
1112 
1113         /*
1114          * Make sure there aren't any processes that still think this
1115          * tty is their controlling tty.
1116          */
1117         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1118                 if ((*p) && (*p)->tty == tty->line)
1119                 (*p)->tty = -1;
1120         }
1121 
1122         if (ldiscs[tty->disc].close != NULL)
1123                 ldiscs[tty->disc].close(tty);
1124 
1125         if (o_tty) {
1126                 if (o_tty->count)
1127                         return;
1128                 else {
1129                         tty_table[PTY_OTHER(dev)] = NULL;
1130                         tty_termios[PTY_OTHER(dev)] = NULL;
1131                 }
1132         }
1133         tty_table[dev] = NULL;
1134         if (IS_A_PTY(dev)) {
1135                 tty_termios[dev] = NULL;
1136                 kfree_s(tp, sizeof(struct termios));
1137         }
1138         if (tty == redirect || o_tty == redirect)
1139                 redirect = NULL;
1140         free_page((unsigned long) tty);
1141         if (o_tty)
1142                 free_page((unsigned long) o_tty);
1143         if (o_tp)
1144                 kfree_s(o_tp, sizeof(struct termios));
1145 }
1146 
1147 /*
1148  * tty_open and tty_release keep up the tty count that contains the
1149  * number of opens done on a tty. We cannot use the inode-count, as
1150  * different inodes might point to the same tty.
1151  *
1152  * Open-counting is needed for pty masters, as well as for keeping
1153  * track of serial lines: DTR is dropped when the last close happens.
1154  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1155  *
1156  * The termios state of a pty is reset on first open so that
1157  * settings don't persist across reuse.
1158  */
1159 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1160 {
1161         struct tty_struct *tty;
1162         int major, minor;
1163         int noctty, retval;
1164 
1165         minor = MINOR(inode->i_rdev);
1166         major = MAJOR(inode->i_rdev);
1167         noctty = filp->f_flags & O_NOCTTY;
1168         if (major == 5) {
1169                 if (!minor) {
1170                         major = 4;
1171                         minor = current->tty;
1172                 }
1173                 noctty = 1;
1174         } else if (major == 4) {
1175                 if (!minor) {
1176                         minor = fg_console + 1;
1177                         noctty = 1;
1178                 }
1179         } else {
1180                 printk("Bad major #%d in tty_open\n", MAJOR(inode->i_rdev));
1181                 return -ENODEV;
1182         }
1183         if (minor <= 0)
1184                 return -ENXIO;
1185         if (IS_A_PTY_MASTER(minor))
1186                 noctty = 1;
1187         filp->f_rdev = (major << 8) | minor;
1188         retval = init_dev(minor);
1189         if (retval)
1190                 return retval;
1191         tty = tty_table[minor];
1192 
1193         /* clean up the packet stuff. */
1194         /*
1195          *  Why is this not done in init_dev?  Right here, if another 
1196          * process opens up a tty in packet mode, all the packet 
1197          * variables get cleared.  Come to think of it, is anything 
1198          * using the packet mode at all???  - Ted, 1/27/93
1199          */
1200         tty->status_changed = 0;
1201         tty->ctrl_status = 0;
1202         tty->packet = 0;
1203 
1204         if (tty->open) {
1205                 retval = tty->open(tty, filp);
1206         } else {
1207                 retval = -ENODEV;
1208         }
1209         if (retval) {
1210                 release_dev(minor, filp);
1211                 return retval;
1212         }
1213         if (!noctty &&
1214             current->leader &&
1215             current->tty<0 &&
1216             tty->session==0) {
1217                 current->tty = minor;
1218                 tty->session = current->session;
1219                 tty->pgrp = current->pgrp;
1220         }
1221         filp->f_rdev = 0x0400 | minor; /* Set it to something normal */
1222         return 0;
1223 }
1224 
1225 /*
1226  * Note that releasing a pty master also releases the child, so
1227  * we have to make the redirection checks after that and on both
1228  * sides of a pty.
1229  */
1230 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1231 {
1232         int dev;
1233 
1234         dev = filp->f_rdev;
1235         if (MAJOR(dev) != 4) {
1236                 printk("tty_release: tty pseudo-major != 4\n");
1237                 return;
1238         }
1239         dev = MINOR(filp->f_rdev);
1240         if (!dev) {
1241                 printk("tty_release: bad f_rdev\n");
1242                 return;
1243         }
1244         release_dev(dev, filp);
1245 }
1246 
1247 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1248 {
1249         int dev;
1250         struct tty_struct * tty;
1251 
1252         dev = filp->f_rdev;
1253         if (MAJOR(dev) != 4) {
1254                 printk("tty_select: tty pseudo-major != 4\n");
1255                 return 0;
1256         }
1257         dev = MINOR(filp->f_rdev);
1258         tty = TTY_TABLE(dev);
1259         if (!tty) {
1260                 printk("tty_select: tty struct for dev %d was NULL\n", dev);
1261                 return 0;
1262         }
1263         switch (sel_type) {
1264                 case SEL_IN:
1265                         if (L_CANON(tty)) {
1266                                 if (available_canon_input(tty))
1267                                         return 1;
1268                         } else if (!EMPTY(&tty->secondary))
1269                                 return 1;
1270                         if (tty->link && !tty->link->count)
1271                                 return 1;
1272 
1273                         /* see if the status byte can be read. */
1274                         if (tty->packet && tty->link &&
1275                             tty->link->status_changed)
1276                                 return 1;
1277 
1278                         select_wait(&tty->secondary.proc_list, wait);
1279                         return 0;
1280                 case SEL_OUT:
1281                         if (!FULL(&tty->write_q))
1282                                 return 1;
1283                         select_wait(&tty->write_q.proc_list, wait);
1284                         return 0;
1285                 case SEL_EX:
1286                         if (tty->link && !tty->link->count)
1287                                 return 1;
1288                         return 0;
1289         }
1290         return 0;
1291 }
1292 
1293 /*
1294  * This implements the "Secure Attention Key" ---  the idea is to
1295  * prevent trojan horses by killing all processes associated with this
1296  * tty when the user hits the "Secure Attention Key".  Required for
1297  * super-paranoid applications --- see the Orange Book for more details.
1298  * 
1299  * This code could be nicer; ideally it should send a HUP, wait a few
1300  * seconds, then send a INT, and then a KILL signal.  But you then
1301  * have to coordinate with the init process, since all processes associated
1302  * with the current tty must be dead before the new getty is allowed
1303  * to spawn.
1304  */
1305 void do_SAK( struct tty_struct *tty)
     /*  */
1306 {
1307         struct task_struct **p;
1308         int line = tty->line;
1309         int session = tty->session;
1310         int             i;
1311         struct file     *filp;
1312         
1313         flush_input(tty);
1314         flush_output(tty);
1315         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1316                 if (!(*p))
1317                         continue;
1318                 if (((*p)->tty == line) ||
1319                     ((session > 0) && ((*p)->session == session)))
1320                         send_sig(SIGKILL, *p, 1);
1321                 else {
1322                         for (i=0; i < NR_FILE; i++) {
1323                                 filp = (*p)->filp[i];
1324                                 if (filp && (filp->f_op == &tty_fops) &&
1325                                     (MINOR(filp->f_rdev) == line)) {
1326                                         send_sig(SIGKILL, *p, 1);
1327                                         break;
1328                                 }
1329                         }
1330                 }
1331         }
1332 }
1333 
1334 /*
1335  * This routine allows a kernel routine to send a large chunk of data
1336  * to a particular tty; if all of the data can be queued up for ouput
1337  * immediately, tty_write_data() will return 0.  If, however, not all
1338  * of the data can be immediately queued for delivery, the number of
1339  * bytes left to be queued up will be returned, and the rest of the
1340  * data will be queued up when there is room.  The callback function
1341  * will be called (with the argument callarg) when the last of the
1342  * data is finally in the queue.
1343  *
1344  * Note that the callback routine will _not_ be called if all of the
1345  * data could be queued immediately.  This is to avoid a problem with
1346  * the kernel stack getting too deep, which might happen if the
1347  * callback routine calls tty_write_data with itself as an argument.
1348  */
1349 int tty_write_data(struct tty_struct *tty, char *bufp, int buflen,
     /*  */
1350                     void (*callback)(void * data), void * callarg)
1351 {
1352         int head, tail, count;
1353         unsigned long flags;
1354         char *p;
1355 
1356 #define VLEFT ((tail-head-1)&(TTY_BUF_SIZE-1))
1357 
1358         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
1359         if (tty->write_data_cnt) {
1360                 __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1361                 return -EBUSY;
1362         }
1363 
1364         head = tty->write_q.head;
1365         tail = tty->write_q.tail;
1366         count = buflen;
1367         p = bufp;
1368 
1369         while (count && VLEFT > 0) {
1370                 tty->write_q.buf[head++] = *p++;
1371                 head &= TTY_BUF_SIZE-1;
1372         }
1373         tty->write_q.head = head;
1374         if (count) {
1375                 tty->write_data_cnt = count;
1376                 tty->write_data_ptr = p;
1377                 tty->write_data_callback = callback;
1378                 tty->write_data_arg = callarg;
1379         }
1380         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1381         return count;
1382 }
1383 
1384 /*
1385  * This routine routine is called after an interrupt has drained a
1386  * tty's write queue, so that there is more space for data waiting to
1387  * be sent in tty->write_data_ptr.
1388  *
1389  * tty_check_write[8] is a bitstring which indicates which ttys
1390  * needs to be processed.
1391  */
1392 void tty_bh_routine(void * unused)
     /*  */
1393 {
1394         int     i, j, line, mask;
1395         int     head, tail, count;
1396         unsigned char * p;
1397         struct tty_struct * tty;
1398 
1399         for (i = 0, line = 0; i < MAX_TTYS / 32; i++) {
1400                 if (!tty_check_write[i]) {
1401                         line += 32;
1402                         continue;
1403                 }
1404                 for (j=0, mask=0; j < 32; j++, line++, mask <<= 1) {
1405                         if (!clear_bit(j, &tty_check_write[i])) {
1406                                 tty = tty_table[line];
1407                                 if (!tty || !tty->write_data_cnt)
1408                                         continue;
1409                                 cli();
1410                                 head = tty->write_q.head;
1411                                 tail = tty->write_q.tail;
1412                                 count = tty->write_data_cnt;
1413                                 p = tty->write_data_ptr;
1414 
1415                                 while (count && VLEFT > 0) {
1416                                         tty->write_q.buf[head++] = *p++;
1417                                         head &= TTY_BUF_SIZE-1;
1418                                 }
1419                                 tty->write_q.head = head;
1420                                 tty->write_data_ptr = p;
1421                                 tty->write_data_cnt = count;
1422                                 sti();
1423                                 if (!count)
1424                                         (tty->write_data_callback)
1425                                                 (tty->write_data_arg);
1426                         }
1427                 }
1428         }
1429         
1430 }
1431 
1432 /*
1433  * This subroutine initializes a tty structure.  We have to set up
1434  * things correctly for each different type of tty.
1435  */
1436 static void initialize_tty_struct(int line, struct tty_struct *tty)
     /*  */
1437 {
1438         memset(tty, 0, sizeof(struct tty_struct));
1439         tty->line = line;
1440         tty->disc = N_TTY;
1441         tty->pgrp = -1;
1442         tty->winsize.ws_row = 0;
1443         tty->winsize.ws_col = 0;
1444         if (IS_A_CONSOLE(line)) {
1445                 tty->open = con_open;
1446                 tty->winsize.ws_row = video_num_lines;
1447                 tty->winsize.ws_col = video_num_columns;
1448         } else if IS_A_SERIAL(line) {
1449                 tty->open = rs_open;
1450         } else if IS_A_PTY(line) {
1451                 tty->open = pty_open;
1452         }
1453 }
1454 
1455 static void initialize_termios(int line, struct termios * tp)
     /*  */
1456 {
1457         memset(tp, 0, sizeof(struct termios));
1458         memcpy(tp->c_cc, INIT_C_CC, NCCS);
1459         if (IS_A_CONSOLE(line)) {
1460                 tp->c_iflag = ICRNL | IXON;
1461                 tp->c_oflag = OPOST | ONLCR;
1462                 tp->c_cflag = B38400 | CS8 | CREAD;
1463                 tp->c_lflag = ISIG | ICANON | ECHO |
1464                         ECHOCTL | ECHOKE;
1465         } else if (IS_A_SERIAL(line)) {
1466                 tp->c_cflag = B2400 | CS8 | CREAD | HUPCL | CLOCAL;
1467         } else if (IS_A_PTY_MASTER(line)) {
1468                 tp->c_cflag = B9600 | CS8 | CREAD;
1469         } else if (IS_A_PTY_SLAVE(line)) {
1470                 tp->c_iflag = ICRNL | IXON;
1471                 tp->c_oflag = OPOST | ONLCR;
1472                 tp->c_cflag = B38400 | CS8 | CREAD;
1473                 tp->c_lflag = ISIG | ICANON | ECHO |
1474                         ECHOCTL | ECHOKE;
1475         }
1476 }
1477 
1478 static struct tty_ldisc tty_ldisc_N_TTY = {
1479         0,                      /* flags */
1480         NULL,                   /* open */
1481         NULL,                   /* close */
1482         read_chan,              /* read */
1483         write_chan,             /* write */
1484         NULL,                   /* ioctl */
1485         copy_to_cooked          /* handler */
1486 };
1487 
1488         
1489 long tty_init(long kmem_start)
     /*  */
1490 {
1491         int i;
1492 
1493         if (sizeof(struct tty_struct) > 4096)
1494                 panic("size of tty structure > 4096!");
1495         if (register_chrdev(4,"tty",&tty_fops))
1496                 panic("unable to get major 4 for tty device");
1497         if (register_chrdev(5,"tty",&tty_fops))
1498                 panic("unable to get major 5 for tty device");
1499         for (i=0 ; i< MAX_TTYS ; i++) {
1500                 tty_table[i] =  0;
1501                 tty_termios[i] = 0;
1502         }
1503         memset(tty_check_write, 0, sizeof(tty_check_write));
1504         bh_base[TTY_BH].routine = tty_bh_routine;
1505 
1506         /* Setup the default TTY line discipline. */
1507         memset(ldiscs, 0, sizeof(ldiscs));
1508         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1509 
1510         kmem_start = kbd_init(kmem_start);
1511         kmem_start = con_init(kmem_start);
1512         kmem_start = rs_init(kmem_start);
1513         return kmem_start;
1514 }
/* */
root/kernel/chr_drv/tty_io.c

DEFINITIONS
