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
tty_lseek
tty_hangup
tty_unhangup
hung_up
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 tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 185 {
 186         return -ESPIPE;
 187 }
 188 
 189 static struct file_operations tty_fops = {
 190         tty_lseek,
 191         tty_read,
 192         tty_write,
 193         NULL,           /* tty_readdir */
 194         tty_select,
 195         tty_ioctl,
 196         NULL,           /* tty_mmap */
 197         tty_open,
 198         tty_release
 199 };
 200 
 201 static struct file_operations hung_up_tty_fops = {
 202         tty_lseek,
 203         hung_up_tty_read,
 204         hung_up_tty_write,
 205         NULL,           /* hung_up_tty_readdir */
 206         hung_up_tty_select,
 207         tty_ioctl,
 208         NULL,           /* hung_up_tty_mmap */
 209         tty_open,
 210         tty_release
 211 };
 212 
 213 void tty_hangup(struct tty_struct * tty)
     /*  */
 214 {
 215         struct file * filp;
 216         int dev;
 217 
 218         if (!tty)
 219                 return;
 220         dev = 0x0400 + tty->line;
 221         filp = file_table + NR_FILE;
 222         while (filp-- > file_table) {
 223                 if (!filp->f_count)
 224                         continue;
 225                 if (filp->f_rdev != dev)
 226                         continue;
 227                 if (filp->f_op != &tty_fops)
 228                         continue;
 229                 filp->f_op = &hung_up_tty_fops;
 230         }
 231         wake_up_interruptible(&tty->secondary.proc_list);
 232         wake_up_interruptible(&tty->read_q.proc_list);
 233         wake_up_interruptible(&tty->write_q.proc_list);
 234         if (tty->session > 0)
 235                 kill_sl(tty->session,SIGHUP,1);
 236 }
 237 
 238 void tty_unhangup(struct file *filp)
     /*  */
 239 {
 240         filp->f_op = &tty_fops;
 241 }
 242 
 243 static inline int hung_up(struct file * filp)
     /*  */
 244 {
 245         return filp->f_op == &hung_up_tty_fops;
 246 }
 247 
 248 /*
 249  * Sometimes we want to wait until a particular VT has been activated. We
 250  * do it in a very simple manner. Everybody waits on a single queue and
 251  * get woken up at once. Those that are satisfied go on with their business,
 252  * while those not ready go back to sleep. Seems overkill to add a wait
 253  * to each vt just for this - usually this does nothing!
 254  */
 255 static struct wait_queue *vt_activate_queue = NULL;
 256 
 257 /*
 258  * Sleeps until a vt is activated, or the task is interrupted. Returns
 259  * 0 if activation, -1 if interrupted.
 260  */
 261 int vt_waitactive(void)
     /*  */
 262 {
 263         interruptible_sleep_on(&vt_activate_queue);
 264         return (current->signal & ~current->blocked) ? -1 : 0;
 265 }
 266 
 267 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 268 
 269 extern int kill_proc(int pid, int sig, int priv);
 270 
 271 /*
 272  * Performs the back end of a vt switch
 273  */
 274 void complete_change_console(unsigned int new_console)
     /*  */
 275 {
 276         unsigned char old_vc_mode;
 277 
 278         if (new_console == fg_console || new_console >= NR_CONSOLES)
 279                 return;
 280 
 281         /*
 282          * If we're switching, we could be going from KD_GRAPHICS to
 283          * KD_TEXT mode or vice versa, which means we need to blank or
 284          * unblank the screen later.
 285          */
 286         old_vc_mode = vt_cons[fg_console].vc_mode;
 287         update_screen(new_console);
 288 
 289         /*
 290          * If this new console is under process control, send it a signal
 291          * telling it that it has acquired. Also check if it has died and
 292          * clean up (similar to logic employed in change_console())
 293          */
 294         if (vt_cons[new_console].vt_mode.mode == VT_PROCESS)
 295         {
 296                 /*
 297                  * Send the signal as privileged - kill_proc() will
 298                  * tell us if the process has gone or something else
 299                  * is awry
 300                  */
 301                 if (kill_proc(vt_cons[new_console].vt_pid,
 302                               vt_cons[new_console].vt_mode.acqsig,
 303                               1) != 0)
 304                 {
 305                 /*
 306                  * The controlling process has died, so we revert back to
 307                  * normal operation. In this case, we'll also change back
 308                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 309                  * but it saves the agony when the X server dies and the screen
 310                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 311                  * this outside of VT_PROCESS but there is no single process
 312                  * to account for and tracking tty count may be undesirable.
 313                  */
 314                         vt_cons[new_console].vc_mode = KD_TEXT;
 315                         clr_vc_kbd_flag(kbd_table + new_console, VC_RAW);
 316                         vt_cons[new_console].vt_mode.mode = VT_AUTO;
 317                         vt_cons[new_console].vt_mode.waitv = 0;
 318                         vt_cons[new_console].vt_mode.relsig = 0;
 319                         vt_cons[new_console].vt_mode.acqsig = 0;
 320                         vt_cons[new_console].vt_mode.frsig = 0;
 321                         vt_cons[new_console].vt_pid = -1;
 322                         vt_cons[new_console].vt_newvt = -1;
 323                 }
 324         }
 325 
 326         /*
 327          * We do this here because the controlling process above may have
 328          * gone, and so there is now a new vc_mode
 329          */
 330         if (old_vc_mode != vt_cons[new_console].vc_mode)
 331         {
 332                 if (vt_cons[new_console].vc_mode == KD_TEXT)
 333                         unblank_screen();
 334                 else
 335                 {
 336                         timer_active &= ~(1<<BLANK_TIMER);
 337                         blank_screen();
 338                 }
 339         }
 340 
 341         /*
 342          * Wake anyone waiting for their VT to activate
 343          */
 344         vt_wake_waitactive();
 345         return;
 346 }
 347 
 348 /*
 349  * Performs the front-end of a vt switch
 350  */
 351 void change_console(unsigned int new_console)
     /*  */
 352 {
 353         if (new_console == fg_console || new_console >= NR_CONSOLES)
 354                 return;
 355 
 356         /*
 357          * If this vt is in process mode, then we need to handshake with
 358          * that process before switching. Essentially, we store where that
 359          * vt wants to switch to and wait for it to tell us when it's done
 360          * (via VT_RELDISP ioctl).
 361          *
 362          * We also check to see if the controlling process still exists.
 363          * If it doesn't, we reset this vt to auto mode and continue.
 364          * This is a cheap way to track process control. The worst thing
 365          * that can happen is: we send a signal to a process, it dies, and
 366          * the switch gets "lost" waiting for a response; hopefully, the
 367          * user will try again, we'll detect the process is gone (unless
 368          * the user waits just the right amount of time :-) and revert the
 369          * vt to auto control.
 370          */
 371         if (vt_cons[fg_console].vt_mode.mode == VT_PROCESS)
 372         {
 373                 /*
 374                  * Send the signal as privileged - kill_proc() will
 375                  * tell us if the process has gone or something else
 376                  * is awry
 377                  */
 378                 if (kill_proc(vt_cons[fg_console].vt_pid,
 379                               vt_cons[fg_console].vt_mode.relsig,
 380                               1) == 0)
 381                 {
 382                         /*
 383                          * It worked. Mark the vt to switch to and
 384                          * return. The process needs to send us a
 385                          * VT_RELDISP ioctl to complete the switch.
 386                          */
 387                         vt_cons[fg_console].vt_newvt = new_console;
 388                         return;
 389                 }
 390 
 391                 /*
 392                  * The controlling process has died, so we revert back to
 393                  * normal operation. In this case, we'll also change back
 394                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 395                  * but it saves the agony when the X server dies and the screen
 396                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 397                  * this outside of VT_PROCESS but there is no single process
 398                  * to account for and tracking tty count may be undesirable.
 399                  */
 400                 vt_cons[fg_console].vc_mode = KD_TEXT;
 401                 clr_vc_kbd_flag(kbd_table + fg_console, VC_RAW);
 402                 vt_cons[fg_console].vt_mode.mode = VT_AUTO;
 403                 vt_cons[fg_console].vt_mode.waitv = 0;
 404                 vt_cons[fg_console].vt_mode.relsig = 0;
 405                 vt_cons[fg_console].vt_mode.acqsig = 0;
 406                 vt_cons[fg_console].vt_mode.frsig = 0;
 407                 vt_cons[fg_console].vt_pid = -1;
 408                 vt_cons[fg_console].vt_newvt = -1;
 409                 /*
 410                  * Fall through to normal (VT_AUTO) handling of the switch...
 411                  */
 412         }
 413 
 414         /*
 415          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 416          */
 417         if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
 418                 return;
 419 
 420         complete_change_console(new_console);
 421 }
 422 
 423 void wait_for_keypress(void)
     /*  */
 424 {
 425         sleep_on(&keypress_wait);
 426 }
 427 
 428 void copy_to_cooked(struct tty_struct * tty)
     /*  */
 429 {
 430         int c;
 431 
 432         if (!tty) {
 433                 printk("copy_to_cooked: called with NULL tty\n");
 434                 return;
 435         }
 436         if (!tty->write) {
 437                 printk("copy_to_cooked: tty %d has null write routine\n",
 438                        tty->line);
 439         }
 440         while (1) {
 441                 /*
 442                  * Check to see how much room we have left in the
 443                  * secondary queue.  Send a throttle command or abort
 444                  * if necessary.
 445                  */
 446                 c = LEFT(&tty->secondary);
 447                 if (tty->throttle && (c < SQ_THRESHOLD_LW)
 448                     && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
 449                         tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
 450                 if (c == 0)
 451                         break;
 452                 c = get_tty_queue(&tty->read_q);
 453                 if (c < 0)
 454                         break;
 455                 if (I_STRP(tty))
 456                         c &= 0x7f;
 457                 if (c==13) {
 458                         if (I_CRNL(tty))
 459                                 c=10;
 460                         else if (I_NOCR(tty))
 461                                 continue;
 462                 } else if (c==10 && I_NLCR(tty))
 463                         c=13;
 464                 if (I_UCLC(tty))
 465                         c=tolower(c);
 466                 if (L_CANON(tty)) {
 467                         if ((KILL_CHAR(tty) != __DISABLED_CHAR) &&
 468                             (c==KILL_CHAR(tty))) {
 469                                 /* deal with killing the input line */
 470                                 while(!(EMPTY(&tty->secondary) ||
 471                                         (c=LAST(&tty->secondary))==10 ||
 472                                         ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 473                                          (c==EOF_CHAR(tty))))) {
 474                                         if (L_ECHO(tty)) {
 475                                                 if (c<32) {
 476                                                         put_tty_queue(8, &tty->write_q);
 477                                                         put_tty_queue(' ', &tty->write_q);
 478                                                         put_tty_queue(8,&tty->write_q);
 479                                                 }
 480                                                 put_tty_queue(8,&tty->write_q);
 481                                                 put_tty_queue(' ',&tty->write_q);
 482                                                 put_tty_queue(8,&tty->write_q);
 483                                         }
 484                                         DEC(tty->secondary.head);
 485                                 }
 486                                 continue;
 487                         }
 488                         if ((ERASE_CHAR(tty) != __DISABLED_CHAR) &&
 489                             (c==ERASE_CHAR(tty))) {
 490                                 if (EMPTY(&tty->secondary) ||
 491                                    (c=LAST(&tty->secondary))==10 ||
 492                                    ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 493                                     (c==EOF_CHAR(tty))))
 494                                         continue;
 495                                 if (L_ECHO(tty)) {
 496                                         if (c<32) {
 497                                                 put_tty_queue(8,&tty->write_q);
 498                                                 put_tty_queue(' ',&tty->write_q);
 499                                                 put_tty_queue(8,&tty->write_q);
 500                                         }
 501                                         put_tty_queue(8,&tty->write_q);
 502                                         put_tty_queue(32,&tty->write_q);
 503                                         put_tty_queue(8,&tty->write_q);
 504                                 }
 505                                 DEC(tty->secondary.head);
 506                                 continue;
 507                         }
 508                 }
 509                 if (I_IXON(tty)) {
 510                         if ((STOP_CHAR(tty) != __DISABLED_CHAR) &&
 511                             (c==STOP_CHAR(tty))) {
 512                                 tty->status_changed = 1;
 513                                 tty->ctrl_status |= TIOCPKT_STOP;
 514                                 tty->stopped=1;
 515                                 continue;
 516                         }
 517                         if (((I_IXANY(tty)) && tty->stopped) ||
 518                             ((START_CHAR(tty) != __DISABLED_CHAR) &&
 519                              (c==START_CHAR(tty)))) {
 520                                 tty->status_changed = 1;
 521                                 tty->ctrl_status |= TIOCPKT_START;
 522                                 tty->stopped=0;
 523                                 continue;
 524                         }
 525                 }
 526                 if (L_ISIG(tty)) {
 527                         if ((INTR_CHAR(tty) != __DISABLED_CHAR) &&
 528                             (c==INTR_CHAR(tty))) {
 529                                 kill_pg(tty->pgrp, SIGINT, 1);
 530                                 flush_input(tty);
 531                                 continue;
 532                         }
 533                         if ((QUIT_CHAR(tty) != __DISABLED_CHAR) &&
 534                             (c==QUIT_CHAR(tty))) {
 535                                 kill_pg(tty->pgrp, SIGQUIT, 1);
 536                                 flush_input(tty);
 537                                 continue;
 538                         }
 539                         if ((SUSPEND_CHAR(tty) != __DISABLED_CHAR) &&
 540                             (c==SUSPEND_CHAR(tty))) {
 541                                 if (!is_orphaned_pgrp(tty->pgrp))
 542                                         kill_pg(tty->pgrp, SIGTSTP, 1);
 543                                 continue;
 544                         }
 545                 }
 546                 if (c==10 || (EOF_CHAR(tty) != __DISABLED_CHAR &&
 547                     c==EOF_CHAR(tty)))
 548                         tty->secondary.data++;
 549                 if ((c==10) && (L_ECHO(tty) || (L_CANON(tty) && L_ECHONL(tty)))) {
 550                         put_tty_queue(10,&tty->write_q);
 551                         put_tty_queue(13,&tty->write_q);
 552                 } else if (L_ECHO(tty)) {
 553                         if (c<32 && L_ECHOCTL(tty)) {
 554                                 put_tty_queue('^',&tty->write_q);
 555                                 put_tty_queue(c+64, &tty->write_q);
 556                         } else
 557                                 put_tty_queue(c, &tty->write_q);
 558                 }
 559                 put_tty_queue(c, &tty->secondary);
 560         }
 561         TTY_WRITE_FLUSH(tty);
 562         if (!EMPTY(&tty->secondary))
 563                 wake_up_interruptible(&tty->secondary.proc_list);
 564         if (tty->write_q.proc_list && LEFT(&tty->write_q) > TTY_BUF_SIZE/2)
 565                 wake_up_interruptible(&tty->write_q.proc_list);
 566         if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
 567             && !clear_bit(TTY_RQ_THROTTLED, &tty->flags))
 568                 tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
 569         if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 570             && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 571                 tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 572 }
 573 
 574 int is_ignored(int sig)
     /*  */
 575 {
 576         return ((current->blocked & (1<<(sig-1))) ||
 577                 (current->sigaction[sig-1].sa_handler == SIG_IGN));
 578 }
 579 
 580 static int available_canon_input(struct tty_struct *);
 581 static void __wait_for_canon_input(struct file * file, struct tty_struct *);
 582 
 583 static void wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 584 {
 585         if (!available_canon_input(tty)) {
 586                 if (current->signal & ~current->blocked)
 587                         return;
 588                 __wait_for_canon_input(file, tty);
 589         }
 590 }
 591 
 592 static int read_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 593 {
 594         struct wait_queue wait = { current, NULL };
 595         int c;
 596         char * b=buf;
 597         int minimum,time;
 598 
 599         if (L_CANON(tty))
 600                 minimum = time = current->timeout = 0;
 601         else {
 602                 time = 10L*tty->termios->c_cc[VTIME];
 603                 minimum = tty->termios->c_cc[VMIN];
 604                 if (minimum)
 605                         current->timeout = 0xffffffff;
 606                 else {
 607                         if (time)
 608                                 current->timeout = time + jiffies;
 609                         else
 610                                 current->timeout = 0;
 611                         time = 0;
 612                         minimum = 1;
 613                 }
 614         }
 615         if (file->f_flags & O_NONBLOCK) {
 616                 time = current->timeout = 0;
 617                 if (L_CANON(tty)) {
 618                         if (!available_canon_input(tty))
 619                                 return -EAGAIN;
 620                 }
 621         } else if (L_CANON(tty)) {
 622                 wait_for_canon_input(file, tty);
 623                 if (current->signal & ~current->blocked)
 624                         return -ERESTARTSYS;
 625         }
 626         if (minimum>nr)
 627                 minimum = nr;
 628 
 629         /* deal with packet mode:  First test for status change */
 630         if (tty->packet && tty->link && tty->link->status_changed) {
 631                 put_fs_byte (tty->link->ctrl_status, b);
 632                 tty->link->status_changed = 0;
 633                 return 1;
 634         }
 635           
 636         /* now bump the buffer up one. */
 637         if (tty->packet) {
 638                 put_fs_byte (0,b++);
 639                 nr--;
 640                 /* this really shouldn't happen, but we need to 
 641                 put it here. */
 642                 if (nr == 0)
 643                         return 1;
 644         }
 645         add_wait_queue(&tty->secondary.proc_list, &wait);
 646         while (nr>0) {
 647                 TTY_READ_FLUSH(tty);
 648                 if (tty->link)
 649                         TTY_WRITE_FLUSH(tty->link);
 650                 while (nr > 0 && ((c = get_tty_queue(&tty->secondary)) >= 0)) {
 651                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 652                              c==EOF_CHAR(tty)) || c==10)
 653                                 tty->secondary.data--;
 654                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 655                              c==EOF_CHAR(tty)) && L_CANON(tty))
 656                                 break;
 657                         put_fs_byte(c,b++);
 658                         nr--;
 659                         if (time)
 660                                 current->timeout = time+jiffies;
 661                         if (c==10 && L_CANON(tty))
 662                                 break;
 663                 };
 664                 wake_up_interruptible(&tty->read_q.proc_list);
 665                 /*
 666                  * If there is enough space in the secondary queue
 667                  * now, let the low-level driver know.
 668                  */
 669                 if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 670                     && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 671                         tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 672                 if (b-buf >= minimum || !current->timeout)
 673                         break;
 674                 if (current->signal & ~current->blocked) 
 675                         break;
 676                 if (tty->link && !tty->link->count)
 677                         break;
 678                 TTY_READ_FLUSH(tty);
 679                 if (tty->link)
 680                         TTY_WRITE_FLUSH(tty->link);
 681                 if (!EMPTY(&tty->secondary))
 682                         continue;
 683                 if (hung_up(file))
 684                         break;
 685                 current->state = TASK_INTERRUPTIBLE;
 686                 if (EMPTY(&tty->secondary))
 687                         schedule();
 688                 current->state = TASK_RUNNING;
 689         }
 690         remove_wait_queue(&tty->secondary.proc_list, &wait);
 691         TTY_READ_FLUSH(tty);
 692         if (tty->link && tty->link->write)
 693                 TTY_WRITE_FLUSH(tty->link);
 694         current->timeout = 0;
 695 
 696         /* packet mode sticks in an extra 0.  If that's all we've got,
 697            we should count it a zero bytes. */
 698         if (tty->packet) {
 699                 if ((b-buf) > 1)
 700                         return b-buf;
 701         } else {
 702                 if (b-buf)
 703                         return b-buf;
 704         }
 705 
 706         if (current->signal & ~current->blocked)
 707                 return -ERESTARTSYS;
 708         if (file->f_flags & O_NONBLOCK)
 709                 return -EAGAIN;
 710         return 0;
 711 }
 712 
 713 static void __wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 714 {
 715         struct wait_queue wait = { current, NULL };
 716 
 717         add_wait_queue(&tty->secondary.proc_list, &wait);
 718         while (1) {
 719                 current->state = TASK_INTERRUPTIBLE;
 720                 if (available_canon_input(tty))
 721                         break;
 722                 if (current->signal & ~current->blocked)
 723                         break;
 724                 if (hung_up(file))
 725                         break;
 726                 schedule();
 727         }
 728         current->state = TASK_RUNNING;
 729         remove_wait_queue(&tty->secondary.proc_list, &wait);
 730 }
 731 
 732 static int available_canon_input(struct tty_struct * tty)
     /*  */
 733 {
 734         TTY_READ_FLUSH(tty);
 735         if (tty->link)
 736                 if (tty->link->count)
 737                         TTY_WRITE_FLUSH(tty->link);
 738                 else
 739                         return 1;
 740         if (FULL(&tty->read_q))
 741                 return 1;
 742         if (tty->secondary.data)
 743                 return 1;
 744         return 0;
 745 }
 746 
 747 static int write_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 748 {
 749         struct wait_queue wait = { current, NULL };
 750         char c, *b=buf;
 751 
 752         if (nr < 0)
 753                 return -EINVAL;
 754         if (!nr)
 755                 return 0;
 756         add_wait_queue(&tty->write_q.proc_list, &wait);
 757         while (nr>0) {
 758                 if (current->signal & ~current->blocked)
 759                         break;
 760                 if (hung_up(file))
 761                         break;
 762                 if (tty->link && !tty->link->count) {
 763                         send_sig(SIGPIPE,current,0);
 764                         break;
 765                 }
 766                 current->state = TASK_INTERRUPTIBLE;
 767                 if (FULL(&tty->write_q)) {
 768                         TTY_WRITE_FLUSH(tty);
 769                         if (FULL(&tty->write_q))
 770                                 schedule();
 771                         current->state = TASK_RUNNING;
 772                         continue;
 773                 }
 774                 current->state = TASK_RUNNING;
 775                 while (nr>0 && !FULL(&tty->write_q)) {
 776                         c=get_fs_byte(b);
 777                         if (O_POST(tty)) {
 778                                 if (c=='\r' && O_CRNL(tty))
 779                                         c='\n';
 780                                 else if (c=='\n' && O_NLRET(tty))
 781                                         c='\r';
 782                                 if (c=='\n' && O_NLCR(tty) &&
 783                                     !set_bit(TTY_CR_PENDING,&tty->flags)) {
 784                                         put_tty_queue(13,&tty->write_q);
 785                                         continue;
 786                                 }
 787                                 if (O_LCUC(tty))
 788                                         c=toupper(c);
 789                         }
 790                         b++; nr--;
 791                         clear_bit(TTY_CR_PENDING,&tty->flags);
 792                         put_tty_queue(c,&tty->write_q);
 793                 }
 794                 if (need_resched)
 795                         schedule();
 796         }
 797         remove_wait_queue(&tty->write_q.proc_list, &wait);
 798         TTY_WRITE_FLUSH(tty);
 799         if (b-buf)
 800                 return b-buf;
 801         if (tty->link && !tty->link->count)
 802                 return -EPIPE;
 803         if (current->signal & ~current->blocked)
 804                 return -ERESTARTSYS;
 805         return 0;
 806 }
 807 
 808 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 809 {
 810         int i, dev;
 811         struct tty_struct * tty;
 812 
 813         dev = file->f_rdev;
 814         if (MAJOR(dev) != 4) {
 815                 printk("tty_read: bad pseudo-major nr #%d\n", MAJOR(dev));
 816                 return -EINVAL;
 817         }
 818         dev = MINOR(dev);
 819         tty = TTY_TABLE(dev);
 820         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 821                 return -EIO;
 822         if (MINOR(inode->i_rdev) && (tty->pgrp > 0) &&
 823             (current->tty == dev) &&
 824             (tty->pgrp != current->pgrp))
 825                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 826                         return -EIO;
 827                 else {
 828                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 829                         return -ERESTARTSYS;
 830                 }
 831         if (ldiscs[tty->disc].read)
 832                 i = (ldiscs[tty->disc].read)(tty,file,buf,count);
 833         else
 834                 i = -EIO;
 835         if (i > 0)
 836                 inode->i_atime = CURRENT_TIME;
 837         return i;
 838 }
 839 
 840 static int tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 841 {
 842         int dev, i, is_console;
 843         struct tty_struct * tty;
 844 
 845         dev = file->f_rdev;
 846         is_console = (inode->i_rdev == 0x0400);
 847         if (MAJOR(dev) != 4) {
 848                 printk("tty_write: pseudo-major != 4\n");
 849                 return -EINVAL;
 850         }
 851         dev = MINOR(dev);
 852         if (is_console && redirect)
 853                 tty = redirect;
 854         else
 855                 tty = TTY_TABLE(dev);
 856         if (!tty || !tty->write || (tty->flags & (1 << TTY_IO_ERROR)))
 857                 return -EIO;
 858         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
 859             (current->tty == dev) && (tty->pgrp != current->pgrp)) {
 860                 if (is_orphaned_pgrp(current->pgrp))
 861                         return -EIO;
 862                 if (!is_ignored(SIGTTOU)) {
 863                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
 864                         return -ERESTARTSYS;
 865                 }
 866         }
 867         if (ldiscs[tty->disc].write)
 868                 i = (ldiscs[tty->disc].write)(tty,file,buf,count);
 869         else
 870                 i = -EIO;
 871         if (i > 0)
 872                 inode->i_mtime = CURRENT_TIME;
 873         return i;
 874 }
 875 
 876 /*
 877  * This is so ripe with races that you should *really* not touch this
 878  * unless you know exactly what you are doing. All the changes have to be
 879  * made atomically, or there may be incorrect pointers all over the place.
 880  */
 881 static int init_dev(int dev)
     /*  */
 882 {
 883         struct tty_struct *tty, *o_tty;
 884         struct termios *tp, *o_tp;
 885         int retval;
 886         int o_dev;
 887 
 888         o_dev = PTY_OTHER(dev);
 889         tty = o_tty = NULL;
 890         tp = o_tp = NULL;
 891 repeat:
 892         retval = -EAGAIN;
 893         if (IS_A_PTY_MASTER(dev) && tty_table[dev] && tty_table[dev]->count)
 894                 goto end_init;
 895         retval = -ENOMEM;
 896         if (!tty_table[dev] && !tty) {
 897                 tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
 898                 if (!tty)
 899                         goto end_init;
 900                 initialize_tty_struct(dev, tty);
 901                 goto repeat;
 902         }
 903         if (!tty_termios[dev] && !tp) {
 904                 tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
 905                 if (!tp)
 906                         goto end_init;
 907                 initialize_termios(dev, tp);
 908                 goto repeat;
 909         }
 910         if (IS_A_PTY(dev)) {
 911                 if (!tty_table[o_dev] && !o_tty) {
 912                         o_tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
 913                         if (!o_tty)
 914                                 goto end_init;
 915                         initialize_tty_struct(o_dev, o_tty);
 916                         goto repeat;
 917                 }
 918                 if (!tty_termios[o_dev] && !o_tp) {
 919                         o_tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
 920                         if (!o_tp)
 921                                 goto end_init;
 922                         initialize_termios(o_dev, o_tp);
 923                         goto repeat;
 924                 }
 925         }
 926         /* Now we have allocated all the structures: update all the pointers.. */
 927         if (!tty_termios[dev]) {
 928                 tty_termios[dev] = tp;
 929                 tp = NULL;
 930         }
 931         if (!tty_table[dev]) {
 932                 tty->termios = tty_termios[dev];
 933                 tty_table[dev] = tty;
 934                 tty = NULL;
 935         }
 936         if (IS_A_PTY(dev)) {
 937                 if (!tty_termios[o_dev]) {
 938                         tty_termios[o_dev] = o_tp;
 939                         o_tp = NULL;
 940                 }
 941                 if (!tty_table[o_dev]) {
 942                         o_tty->termios = tty_termios[o_dev];
 943                         tty_table[o_dev] = o_tty;
 944                         o_tty = NULL;
 945                 }
 946                 tty_table[dev]->link = tty_table[o_dev];
 947                 tty_table[o_dev]->link = tty_table[dev];
 948         }
 949         tty_table[dev]->count++;
 950         if (IS_A_PTY_MASTER(dev))
 951                 tty_table[o_dev]->count++;
 952         retval = 0;
 953 end_init:
 954         if (tty)
 955                 free_page((unsigned long) tty);
 956         if (o_tty)
 957                 free_page((unsigned long) tty);
 958         if (tp)
 959                 kfree_s(tp, sizeof(struct termios));
 960         if (o_tp)
 961                 kfree_s(o_tp, sizeof(struct termios));
 962         return retval;
 963 }
 964 
 965 /*
 966  * Even releasing the tty structures is a tricky business.. We have
 967  * to be very careful that the structures are all released at the
 968  * same time, as interrupts might otherwise get the wrong pointers.
 969  */
 970 static void release_dev(int dev, struct file * filp)
     /*  */
 971 {
 972         struct tty_struct *tty, *o_tty;
 973         struct termios *tp, *o_tp;
 974 
 975         tty = tty_table[dev];
 976         tp = tty_termios[dev];
 977         o_tty = NULL;
 978         o_tp = NULL;
 979         if (!tty) {
 980                 printk("release_dev: tty_table[%d] was NULL\n", dev);
 981                 return;
 982         }
 983         if (!tp) {
 984                 printk("release_dev: tty_termios[%d] was NULL\n", dev);
 985                 return;
 986         }
 987         if (IS_A_PTY(dev)) {
 988                 o_tty = tty_table[PTY_OTHER(dev)];
 989                 o_tp = tty_termios[PTY_OTHER(dev)];
 990                 if (!o_tty) {
 991                         printk("release_dev: pty pair(%d) was NULL\n", dev);
 992                         return;
 993                 }
 994                 if (!o_tp) {
 995                         printk("release_dev: pty pair(%d) termios was NULL\n", dev);
 996                         return;
 997                 }
 998                 if (tty->link != o_tty || o_tty->link != tty) {
 999                         printk("release_dev: bad pty pointers\n");
1000                         return;
1001                 }
1002         }
1003         tty->write_data_cnt = 0; /* Clear out pending trash */
1004         if (tty->close)
1005                 tty->close(tty, filp);
1006         if (IS_A_PTY_MASTER(dev)) {
1007                 if (--tty->link->count < 0) {
1008                         printk("release_dev: bad tty slave count (dev = %d): %d\n",
1009                                dev, tty->count);
1010                         tty->link->count = 0;
1011                 }
1012         }
1013         if (--tty->count < 0) {
1014                 printk("release_dev: bad tty_table[%d]->count: %d\n",
1015                        dev, tty->count);
1016                 tty->count = 0;
1017         }
1018         if (tty->count)
1019                 return;
1020 
1021         if (ldiscs[tty->disc].close != NULL)
1022                 ldiscs[tty->disc].close(tty);
1023 
1024         if (o_tty) {
1025                 if (o_tty->count)
1026                         return;
1027                 else {
1028                         tty_table[PTY_OTHER(dev)] = NULL;
1029                         tty_termios[PTY_OTHER(dev)] = NULL;
1030                 }
1031         }
1032         tty_table[dev] = NULL;
1033         if (IS_A_PTY(dev)) {
1034                 tty_termios[dev] = NULL;
1035                 kfree_s(tp, sizeof(struct termios));
1036         }
1037         if (tty == redirect || o_tty == redirect)
1038                 redirect = NULL;
1039         free_page((unsigned long) tty);
1040         if (o_tty)
1041                 free_page((unsigned long) o_tty);
1042         if (o_tp)
1043                 kfree_s(o_tp, sizeof(struct termios));
1044 }
1045 
1046 /*
1047  * tty_open and tty_release keep up the tty count that contains the
1048  * number of opens done on a tty. We cannot use the inode-count, as
1049  * different inodes might point to the same tty.
1050  *
1051  * Open-counting is needed for pty masters, as well as for keeping
1052  * track of serial lines: DTR is dropped when the last close happens.
1053  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1054  *
1055  * The termios state of a pty is reset on first open so that
1056  * settings don't persist across reuse.
1057  */
1058 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1059 {
1060         struct tty_struct *tty;
1061         int major, minor;
1062         int noctty, retval;
1063 
1064         minor = MINOR(inode->i_rdev);
1065         major = MAJOR(inode->i_rdev);
1066         noctty = filp->f_flags & O_NOCTTY;
1067         if (major == 5) {
1068                 if (!minor) {
1069                         major = 4;
1070                         minor = current->tty;
1071                 }
1072                 noctty = 1;
1073         } else if (major == 4) {
1074                 if (!minor) {
1075                         minor = fg_console + 1;
1076                         noctty = 1;
1077                 }
1078         } else {
1079                 printk("Bad major #%d in tty_open\n", MAJOR(inode->i_rdev));
1080                 return -ENODEV;
1081         }
1082         if (minor <= 0)
1083                 return -ENXIO;
1084         if (IS_A_PTY_MASTER(minor))
1085                 noctty = 1;
1086         filp->f_rdev = (major << 8) | minor;
1087         retval = init_dev(minor);
1088         if (retval)
1089                 return retval;
1090         tty = tty_table[minor];
1091 
1092         /* clean up the packet stuff. */
1093         /*
1094          *  Why is this not done in init_dev?  Right here, if another 
1095          * process opens up a tty in packet mode, all the packet 
1096          * variables get cleared.  Come to think of it, is anything 
1097          * using the packet mode at all???  - Ted, 1/27/93
1098          */
1099         tty->status_changed = 0;
1100         tty->ctrl_status = 0;
1101         tty->packet = 0;
1102 
1103         if (tty->open) {
1104                 retval = tty->open(tty, filp);
1105         } else {
1106                 retval = -ENODEV;
1107         }
1108         if (retval) {
1109                 release_dev(minor, filp);
1110                 return retval;
1111         }
1112         if (!noctty &&
1113             current->leader &&
1114             current->tty<0 &&
1115             tty->session==0) {
1116                 current->tty = minor;
1117                 tty->session = current->session;
1118                 tty->pgrp = current->pgrp;
1119         }
1120         filp->f_rdev = 0x0400 | minor; /* Set it to something normal */
1121         return 0;
1122 }
1123 
1124 /*
1125  * Note that releasing a pty master also releases the child, so
1126  * we have to make the redirection checks after that and on both
1127  * sides of a pty.
1128  */
1129 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1130 {
1131         int dev;
1132 
1133         dev = filp->f_rdev;
1134         if (MAJOR(dev) != 4) {
1135                 printk("tty_release: tty pseudo-major != 4\n");
1136                 return;
1137         }
1138         dev = MINOR(filp->f_rdev);
1139         if (!dev) {
1140                 printk("tty_release: bad f_rdev\n");
1141                 return;
1142         }
1143         release_dev(dev, filp);
1144 }
1145 
1146 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1147 {
1148         int dev;
1149         struct tty_struct * tty;
1150 
1151         dev = filp->f_rdev;
1152         if (MAJOR(dev) != 4) {
1153                 printk("tty_select: tty pseudo-major != 4\n");
1154                 return 0;
1155         }
1156         dev = MINOR(filp->f_rdev);
1157         tty = TTY_TABLE(dev);
1158         if (!tty) {
1159                 printk("tty_select: tty struct for dev %d was NULL\n", dev);
1160                 return 0;
1161         }
1162         switch (sel_type) {
1163                 case SEL_IN:
1164                         if (L_CANON(tty)) {
1165                                 if (available_canon_input(tty))
1166                                         return 1;
1167                         } else if (!EMPTY(&tty->secondary))
1168                                 return 1;
1169                         if (tty->link && !tty->link->count)
1170                                 return 1;
1171 
1172                         /* see if the status byte can be read. */
1173                         if (tty->packet && tty->link &&
1174                             tty->link->status_changed)
1175                                 return 1;
1176 
1177                         select_wait(&tty->secondary.proc_list, wait);
1178                         return 0;
1179                 case SEL_OUT:
1180                         if (!FULL(&tty->write_q))
1181                                 return 1;
1182                         select_wait(&tty->write_q.proc_list, wait);
1183                         return 0;
1184                 case SEL_EX:
1185                         if (tty->link && !tty->link->count)
1186                                 return 1;
1187                         return 0;
1188         }
1189         return 0;
1190 }
1191 
1192 /*
1193  * This implements the "Secure Attention Key" ---  the idea is to
1194  * prevent trojan horses by killing all processes associated with this
1195  * tty when the user hits the "Secure Attention Key".  Required for
1196  * super-paranoid applications --- see the Orange Book for more details.
1197  * 
1198  * This code could be nicer; ideally it should send a HUP, wait a few
1199  * seconds, then send a INT, and then a KILL signal.  But you then
1200  * have to coordinate with the init process, since all processes associated
1201  * with the current tty must be dead before the new getty is allowed
1202  * to spawn.
1203  */
1204 void do_SAK( struct tty_struct *tty)
     /*  */
1205 {
1206         struct task_struct **p;
1207         int line = tty->line;
1208         int session = tty->session;
1209         int             i;
1210         struct file     *filp;
1211         
1212         flush_input(tty);
1213         flush_output(tty);
1214         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1215                 if (!(*p))
1216                         continue;
1217                 if (((*p)->tty == line) ||
1218                     ((session > 0) && ((*p)->session == session)))
1219                         send_sig(SIGKILL, *p, 1);
1220                 else {
1221                         for (i=0; i < NR_FILE; i++) {
1222                                 filp = (*p)->filp[i];
1223                                 if (filp && (filp->f_op == &tty_fops) &&
1224                                     (MINOR(filp->f_rdev) == line)) {
1225                                         send_sig(SIGKILL, *p, 1);
1226                                         break;
1227                                 }
1228                         }
1229                 }
1230         }
1231 }
1232 
1233 /*
1234  * This routine allows a kernel routine to send a large chunk of data
1235  * to a particular tty; if all of the data can be queued up for ouput
1236  * immediately, tty_write_data() will return 0.  If, however, not all
1237  * of the data can be immediately queued for delivery, the number of
1238  * bytes left to be queued up will be returned, and the rest of the
1239  * data will be queued up when there is room.  The callback function
1240  * will be called (with the argument callarg) when the last of the
1241  * data is finally in the queue.
1242  *
1243  * Note that the callback routine will _not_ be called if all of the
1244  * data could be queued immediately.  This is to avoid a problem with
1245  * the kernel stack getting too deep, which might happen if the
1246  * callback routine calls tty_write_data with itself as an argument.
1247  */
1248 int tty_write_data(struct tty_struct *tty, char *bufp, int buflen,
     /*  */
1249                     void (*callback)(void * data), void * callarg)
1250 {
1251         int head, tail, count;
1252         unsigned long flags;
1253         char *p;
1254 
1255 #define VLEFT ((tail-head-1)&(TTY_BUF_SIZE-1))
1256 
1257         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
1258         if (tty->write_data_cnt) {
1259                 __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1260                 return -EBUSY;
1261         }
1262 
1263         head = tty->write_q.head;
1264         tail = tty->write_q.tail;
1265         count = buflen;
1266         p = bufp;
1267 
1268         while (count && VLEFT > 0) {
1269                 tty->write_q.buf[head++] = *p++;
1270                 head &= TTY_BUF_SIZE-1;
1271         }
1272         tty->write_q.head = head;
1273         if (count) {
1274                 tty->write_data_cnt = count;
1275                 tty->write_data_ptr = p;
1276                 tty->write_data_callback = callback;
1277                 tty->write_data_arg = callarg;
1278         }
1279         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1280         return count;
1281 }
1282 
1283 /*
1284  * This routine routine is called after an interrupt has drained a
1285  * tty's write queue, so that there is more space for data waiting to
1286  * be sent in tty->write_data_ptr.
1287  *
1288  * tty_check_write[8] is a bitstring which indicates which ttys
1289  * needs to be processed.
1290  */
1291 void tty_bh_routine()
     /*  */
1292 {
1293         int     i, j, line, mask;
1294         int     head, tail, count;
1295         unsigned char * p;
1296         struct tty_struct * tty;
1297 
1298         for (i = 0, line = 0; i < MAX_TTYS / 32; i++) {
1299                 if (!tty_check_write[i]) {
1300                         line += 32;
1301                         continue;
1302                 }
1303                 for (j=0, mask=0; j < 32; j++, line++, mask <<= 1) {
1304                         if (!clear_bit(j, &tty_check_write[i])) {
1305                                 tty = tty_table[line];
1306                                 if (!tty || !tty->write_data_cnt)
1307                                         continue;
1308                                 cli();
1309                                 head = tty->write_q.head;
1310                                 tail = tty->write_q.tail;
1311                                 count = tty->write_data_cnt;
1312                                 p = tty->write_data_ptr;
1313 
1314                                 while (count && VLEFT > 0) {
1315                                         tty->write_q.buf[head++] = *p++;
1316                                         head &= TTY_BUF_SIZE-1;
1317                                 }
1318                                 tty->write_q.head = head;
1319                                 tty->write_data_ptr = p;
1320                                 tty->write_data_cnt = count;
1321                                 sti();
1322                                 if (!count)
1323                                         (tty->write_data_callback)
1324                                                 (tty->write_data_arg);
1325                         }
1326                 }
1327         }
1328         
1329 }
1330 
1331 /*
1332  * This subroutine initializes a tty structure.  We have to set up
1333  * things correctly for each different type of tty.
1334  */
1335 static void initialize_tty_struct(int line, struct tty_struct *tty)
     /*  */
1336 {
1337         memset(tty, 0, sizeof(struct tty_struct));
1338         tty->line = line;
1339         tty->disc = N_TTY;
1340         tty->pgrp = -1;
1341         tty->winsize.ws_row = 24;
1342         tty->winsize.ws_col = 80;
1343         if (IS_A_CONSOLE(line)) {
1344                 tty->open = con_open;
1345                 tty->winsize.ws_row = video_num_lines;
1346                 tty->winsize.ws_col = video_num_columns;
1347         } else if IS_A_SERIAL(line) {
1348                 tty->open = rs_open;
1349         } else if IS_A_PTY(line) {
1350                 tty->open = pty_open;
1351         }
1352 }
1353 
1354 static void initialize_termios(int line, struct termios * tp)
     /*  */
1355 {
1356         memset(tp, 0, sizeof(struct termios));
1357         memcpy(tp->c_cc, INIT_C_CC, NCCS);
1358         if (IS_A_CONSOLE(line)) {
1359                 tp->c_iflag = ICRNL | IXON;
1360                 tp->c_oflag = OPOST | ONLCR;
1361                 tp->c_cflag = B38400 | CS8 | CREAD;
1362                 tp->c_lflag = ISIG | ICANON | ECHO |
1363                         ECHOCTL | ECHOKE;
1364         } else if (IS_A_SERIAL(line)) {
1365                 tp->c_cflag = B2400 | CS8 | CREAD | HUPCL | CLOCAL;
1366         } else if (IS_A_PTY_MASTER(line)) {
1367                 tp->c_cflag = B9600 | CS8 | CREAD;
1368         } else if (IS_A_PTY_SLAVE(line)) {
1369                 tp->c_iflag = ICRNL | IXON;
1370                 tp->c_oflag = OPOST | ONLCR;
1371                 tp->c_cflag = B38400 | CS8 | CREAD;
1372                 tp->c_lflag = ISIG | ICANON | ECHO |
1373                         ECHOCTL | ECHOKE;
1374         }
1375 }
1376 
1377 static struct tty_ldisc tty_ldisc_N_TTY = {
1378         0,                      /* flags */
1379         NULL,                   /* open */
1380         NULL,                   /* close */
1381         read_chan,              /* read */
1382         write_chan,             /* write */
1383         NULL,                   /* ioctl */
1384         copy_to_cooked          /* handler */
1385 };
1386 
1387         
1388 long tty_init(long kmem_start)
     /*  */
1389 {
1390         int i;
1391 
1392         if (sizeof(struct tty_struct) > 4096)
1393                 panic("size of tty structure > 4096!");
1394         
1395         chrdev_fops[4] = &tty_fops;
1396         chrdev_fops[5] = &tty_fops;
1397         for (i=0 ; i< MAX_TTYS ; i++) {
1398                 tty_table[i] =  0;
1399                 tty_termios[i] = 0;
1400         }
1401         memset(tty_check_write, 0, sizeof(tty_check_write));
1402         bh_base[TTY_BH].routine = tty_bh_routine;
1403 
1404         /* Setup the default TTY line discipline. */
1405         memset(ldiscs, 0, sizeof(ldiscs));
1406         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1407 
1408         kmem_start = kbd_init(kmem_start);
1409         kmem_start = con_init(kmem_start);
1410         kmem_start = rs_init(kmem_start);
1411         return kmem_start;
1412 }
/* */
root/kernel/chr_drv/tty_io.c

DEFINITIONS
