kernel/chr_drv/tty

/* */
This source file includes following definitions.
tty_register_ldisc
put_tty_queue
get_tty_queue
tty_read_raw_data
tty_write_flush
tty_read_flush
hung_up_tty_read
hung_up_tty_write
hung_up_tty_select
hung_up_tty_ioctl
tty_lseek
do_tty_hangup
tty_hangup
tty_vhangup
tty_unhangup
tty_hung_up_p
vt_waitactive
complete_change_console
change_console
wait_for_keypress
copy_to_cooked
is_ignored
wait_for_canon_input
read_chan
__wait_for_canon_input
available_canon_input
write_chan
tty_read
tty_write
init_dev
release_dev
tty_open
tty_release
tty_select
do_SAK
tty_write_data
tty_bh_routine
initialize_tty_struct
initialize_termios
tty_init
   1 /*
   2  *  linux/kernel/tty_io.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
   9  * or rs-channels. It also implements echoing, cooked mode etc.
  10  *
  11  * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
  12  *
  13  * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
  14  * tty_struct and tty_queue structures.  Previously there was a array
  15  * of 256 tty_struct's which was statically allocated, and the
  16  * tty_queue structures were allocated at boot time.  Both are now
  17  * dynamically allocated only when the tty is open.
  18  *
  19  * Also restructured routines so that there is more of a separation
  20  * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
  21  * the low-level tty routines (serial.c, pty.c, console.c).  This
  22  * makes for cleaner and more compact code.  -TYT, 9/17/92 
  23  *
  24  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
  25  * which can be dynamically activated and de-activated by the line
  26  * discipline handling modules (like SLIP).
  27  *
  28  * NOTE: pay no attention to the line discpline code (yet); its
  29  * interface is still subject to change in this version...
  30  * -- TYT, 1/31/92
  31  *
  32  * Added functionality to the OPOST tty handling.  No delays, but all
  33  * other bits should be there.
  34  *      -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
  35  */
  36 
  37 #include <linux/types.h>
  38 #include <linux/errno.h>
  39 #include <linux/signal.h>
  40 #include <linux/fcntl.h>
  41 #include <linux/sched.h>
  42 #include <linux/tty.h>
  43 #include <linux/timer.h>
  44 #include <linux/ctype.h>
  45 #include <linux/kd.h>
  46 #include <linux/mm.h>
  47 #include <linux/string.h>
  48 #include <linux/keyboard.h>
  49 
  50 #include <asm/segment.h>
  51 #include <asm/system.h>
  52 #include <asm/bitops.h>
  53 
  54 #include "vt_kern.h"
  55 
  56 #define MAX_TTYS 256
  57 
  58 struct tty_struct *tty_table[MAX_TTYS];
  59 struct termios *tty_termios[MAX_TTYS];  /* We need to keep the termios state */
  60                                         /* around, even when a tty is closed */
  61 struct tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
  62 int tty_check_write[MAX_TTYS/32];       /* bitfield for the bh handler */
  63 
  64 /*
  65  * fg_console is the current virtual console,
  66  * redirect is the pseudo-tty that console output
  67  * is redirected to if asked by TIOCCONS.
  68  */
  69 int fg_console = 0;
  70 struct tty_struct * redirect = NULL;
  71 struct wait_queue * keypress_wait = NULL;
  72 
  73 static void initialize_tty_struct(int line, struct tty_struct *tty);
  74 static void initialize_termios(int line, struct termios *tp);
  75 
  76 static int tty_read(struct inode *, struct file *, char *, int);
  77 static int tty_write(struct inode *, struct file *, char *, int);
  78 static int tty_select(struct inode *, struct file *, int, select_table *);
  79 static int tty_open(struct inode *, struct file *);
  80 static void tty_release(struct inode *, struct file *);
  81 
  82 int tty_register_ldisc(int disc, struct tty_ldisc *new)
     /*  */
  83 {
  84         if (disc < N_TTY || disc >= NR_LDISCS)
  85                 return -EINVAL;
  86         
  87         if (new) {
  88                 ldiscs[disc] = *new;
  89                 ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
  90         } else
  91                 memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
  92         
  93         return 0;
  94 }
  95 
  96 void put_tty_queue(char c, struct tty_queue * queue)
     /*  */
  97 {
  98         int head;
  99         unsigned long flags;
 100 
 101         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
 102         head = (queue->head + 1) & (TTY_BUF_SIZE-1);
 103         if (head != queue->tail) {
 104                 queue->buf[queue->head] = c;
 105                 queue->head = head;
 106         }
 107         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
 108 }
 109 
 110 int get_tty_queue(struct tty_queue * queue)
     /*  */
 111 {
 112         int result = -1;
 113         unsigned long flags;
 114 
 115         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
 116         if (queue->tail != queue->head) {
 117                 result = 0xff & queue->buf[queue->tail];
 118                 queue->tail = (queue->tail + 1) & (TTY_BUF_SIZE-1);
 119         }
 120         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
 121         return result;
 122 }
 123 
 124 /*
 125  * This routine copies out a maximum of buflen characters from the
 126  * read_q; it is a convenience for line disciplins so they can grab a
 127  * large block of data without calling get_tty_char directly.  It
 128  * returns the number of characters actually read.
 129  */
 130 int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp, int buflen)
     /*  */
 131 {
 132         int     result = 0;
 133         unsigned char   *p = bufp;
 134         unsigned long flags;
 135         int head, tail;
 136         
 137         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
 138         tail = tty->read_q.tail;
 139         head = tty->read_q.head;
 140         while ((result < buflen) && (tail!=head)) {
 141                 *p++ =  tty->read_q.buf[tail++];
 142                 tail &= TTY_BUF_SIZE-1;
 143                 result++;
 144         }
 145         tty->read_q.tail = tail;
 146         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
 147         return result;
 148 }
 149 
 150 
 151 void tty_write_flush(struct tty_struct * tty)
     /*  */
 152 {
 153         if (!tty->write || EMPTY(&tty->write_q))
 154                 return;
 155         if (set_bit(TTY_WRITE_BUSY,&tty->flags))
 156                 return;
 157         tty->write(tty);
 158         if (clear_bit(TTY_WRITE_BUSY,&tty->flags))
 159                 printk("tty_write_flush: bit already cleared\n");
 160 }
 161 
 162 void tty_read_flush(struct tty_struct * tty)
     /*  */
 163 {
 164         if (!tty || EMPTY(&tty->read_q))
 165                 return;
 166         if (set_bit(TTY_READ_BUSY, &tty->flags))
 167                 return;
 168         ldiscs[tty->disc].handler(tty);
 169         if (clear_bit(TTY_READ_BUSY, &tty->flags))
 170                 printk("tty_read_flush: bit already cleared\n");
 171 }
 172 
 173 static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 174 {
 175         return 0;
 176 }
 177 
 178 static int hung_up_tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 179 {
 180         return -EIO;
 181 }
 182 
 183 static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
 184 {
 185         return 1;
 186 }
 187 
 188 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
     /*  */
 189                              unsigned int cmd, unsigned long arg)
 190 {
 191         return -EIO;
 192 }
 193 
 194 static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 195 {
 196         return -ESPIPE;
 197 }
 198 
 199 static struct file_operations tty_fops = {
 200         tty_lseek,
 201         tty_read,
 202         tty_write,
 203         NULL,           /* tty_readdir */
 204         tty_select,
 205         tty_ioctl,
 206         NULL,           /* tty_mmap */
 207         tty_open,
 208         tty_release
 209 };
 210 
 211 static struct file_operations hung_up_tty_fops = {
 212         tty_lseek,
 213         hung_up_tty_read,
 214         hung_up_tty_write,
 215         NULL,           /* hung_up_tty_readdir */
 216         hung_up_tty_select,
 217         tty_ioctl,
 218         NULL,           /* hung_up_tty_mmap */
 219         tty_open,
 220         tty_release
 221 };
 222 
 223 static struct file_operations vhung_up_tty_fops = {
 224         tty_lseek,
 225         hung_up_tty_read,
 226         hung_up_tty_write,
 227         NULL,           /* hung_up_tty_readdir */
 228         hung_up_tty_select,
 229         hung_up_tty_ioctl,
 230         NULL,           /* hung_up_tty_mmap */
 231         tty_open,
 232         tty_release
 233 };
 234 
 235 void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
     /*  */
 236 {
 237         int i;
 238         struct file * filp;
 239         struct task_struct **p;
 240         int dev;
 241 
 242         if (!tty)
 243                 return;
 244         dev = 0x0400 + tty->line;
 245         for (filp = first_file, i=0; i<nr_files; i++, filp = filp->f_next) {
 246                 if (!filp->f_count)
 247                         continue;
 248                 if (filp->f_rdev != dev)
 249                         continue;
 250                 if (filp->f_inode && filp->f_inode->i_rdev == 0x0400)
 251                         continue;
 252                 if (filp->f_op != &tty_fops)
 253                         continue;
 254                 filp->f_op = fops;
 255         }
 256         wake_up_interruptible(&tty->secondary.proc_list);
 257         wake_up_interruptible(&tty->read_q.proc_list);
 258         wake_up_interruptible(&tty->write_q.proc_list);
 259         if (tty->session > 0)
 260                 kill_sl(tty->session,SIGHUP,1);
 261         tty->session = 0;
 262         tty->pgrp = -1;
 263         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
 264                 if ((*p) && (*p)->tty == tty->line)
 265                         (*p)->tty = -1;
 266         }
 267 }
 268 
 269 void tty_hangup(struct tty_struct * tty)
     /*  */
 270 {
 271         do_tty_hangup(tty, &hung_up_tty_fops);
 272 }
 273 
 274 void tty_vhangup(struct tty_struct * tty)
     /*  */
 275 {
 276         do_tty_hangup(tty, &vhung_up_tty_fops);
 277 }
 278 
 279 void tty_unhangup(struct file *filp)
     /*  */
 280 {
 281         filp->f_op = &tty_fops;
 282 }
 283 
 284 inline int tty_hung_up_p(struct file * filp)
     /*  */
 285 {
 286         return ((filp->f_op == &hung_up_tty_fops) ||
 287                 (filp->f_op == &vhung_up_tty_fops));
 288 }
 289 
 290 /*
 291  * Sometimes we want to wait until a particular VT has been activated. We
 292  * do it in a very simple manner. Everybody waits on a single queue and
 293  * get woken up at once. Those that are satisfied go on with their business,
 294  * while those not ready go back to sleep. Seems overkill to add a wait
 295  * to each vt just for this - usually this does nothing!
 296  */
 297 static struct wait_queue *vt_activate_queue = NULL;
 298 
 299 /*
 300  * Sleeps until a vt is activated, or the task is interrupted. Returns
 301  * 0 if activation, -1 if interrupted.
 302  */
 303 int vt_waitactive(void)
     /*  */
 304 {
 305         interruptible_sleep_on(&vt_activate_queue);
 306         return (current->signal & ~current->blocked) ? -1 : 0;
 307 }
 308 
 309 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 310 
 311 extern int kill_proc(int pid, int sig, int priv);
 312 
 313 /*
 314  * Performs the back end of a vt switch
 315  */
 316 void complete_change_console(unsigned int new_console)
     /*  */
 317 {
 318         unsigned char old_vc_mode;
 319 
 320         if (new_console == fg_console || new_console >= NR_CONSOLES)
 321                 return;
 322 
 323         /*
 324          * If we're switching, we could be going from KD_GRAPHICS to
 325          * KD_TEXT mode or vice versa, which means we need to blank or
 326          * unblank the screen later.
 327          */
 328         old_vc_mode = vt_cons[fg_console].vc_mode;
 329         update_screen(new_console);
 330 
 331         /*
 332          * If this new console is under process control, send it a signal
 333          * telling it that it has acquired. Also check if it has died and
 334          * clean up (similar to logic employed in change_console())
 335          */
 336         if (vt_cons[new_console].vt_mode.mode == VT_PROCESS)
 337         {
 338                 /*
 339                  * Send the signal as privileged - kill_proc() will
 340                  * tell us if the process has gone or something else
 341                  * is awry
 342                  */
 343                 if (kill_proc(vt_cons[new_console].vt_pid,
 344                               vt_cons[new_console].vt_mode.acqsig,
 345                               1) != 0)
 346                 {
 347                 /*
 348                  * The controlling process has died, so we revert back to
 349                  * normal operation. In this case, we'll also change back
 350                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 351                  * but it saves the agony when the X server dies and the screen
 352                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 353                  * this outside of VT_PROCESS but there is no single process
 354                  * to account for and tracking tty count may be undesirable.
 355                  */
 356                         vt_cons[new_console].vc_mode = KD_TEXT;
 357                         clr_vc_kbd_flag(kbd_table + new_console, VC_RAW);
 358                         vt_cons[new_console].vt_mode.mode = VT_AUTO;
 359                         vt_cons[new_console].vt_mode.waitv = 0;
 360                         vt_cons[new_console].vt_mode.relsig = 0;
 361                         vt_cons[new_console].vt_mode.acqsig = 0;
 362                         vt_cons[new_console].vt_mode.frsig = 0;
 363                         vt_cons[new_console].vt_pid = -1;
 364                         vt_cons[new_console].vt_newvt = -1;
 365                 }
 366         }
 367 
 368         /*
 369          * We do this here because the controlling process above may have
 370          * gone, and so there is now a new vc_mode
 371          */
 372         if (old_vc_mode != vt_cons[new_console].vc_mode)
 373         {
 374                 if (vt_cons[new_console].vc_mode == KD_TEXT)
 375                         unblank_screen();
 376                 else {
 377                         timer_active &= ~(1<<BLANK_TIMER);
 378                         blank_screen();
 379                 }
 380         }
 381 
 382         /*
 383          * Wake anyone waiting for their VT to activate
 384          */
 385         vt_wake_waitactive();
 386         return;
 387 }
 388 
 389 /*
 390  * Performs the front-end of a vt switch
 391  */
 392 void change_console(unsigned int new_console)
     /*  */
 393 {
 394         if (new_console == fg_console || new_console >= NR_CONSOLES)
 395                 return;
 396 
 397         /*
 398          * If this vt is in process mode, then we need to handshake with
 399          * that process before switching. Essentially, we store where that
 400          * vt wants to switch to and wait for it to tell us when it's done
 401          * (via VT_RELDISP ioctl).
 402          *
 403          * We also check to see if the controlling process still exists.
 404          * If it doesn't, we reset this vt to auto mode and continue.
 405          * This is a cheap way to track process control. The worst thing
 406          * that can happen is: we send a signal to a process, it dies, and
 407          * the switch gets "lost" waiting for a response; hopefully, the
 408          * user will try again, we'll detect the process is gone (unless
 409          * the user waits just the right amount of time :-) and revert the
 410          * vt to auto control.
 411          */
 412         if (vt_cons[fg_console].vt_mode.mode == VT_PROCESS)
 413         {
 414                 /*
 415                  * Send the signal as privileged - kill_proc() will
 416                  * tell us if the process has gone or something else
 417                  * is awry
 418                  */
 419                 if (kill_proc(vt_cons[fg_console].vt_pid,
 420                               vt_cons[fg_console].vt_mode.relsig,
 421                               1) == 0)
 422                 {
 423                         /*
 424                          * It worked. Mark the vt to switch to and
 425                          * return. The process needs to send us a
 426                          * VT_RELDISP ioctl to complete the switch.
 427                          */
 428                         vt_cons[fg_console].vt_newvt = new_console;
 429                         return;
 430                 }
 431 
 432                 /*
 433                  * The controlling process has died, so we revert back to
 434                  * normal operation. In this case, we'll also change back
 435                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 436                  * but it saves the agony when the X server dies and the screen
 437                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 438                  * this outside of VT_PROCESS but there is no single process
 439                  * to account for and tracking tty count may be undesirable.
 440                  */
 441                 vt_cons[fg_console].vc_mode = KD_TEXT;
 442                 clr_vc_kbd_flag(kbd_table + fg_console, VC_RAW);
 443                 vt_cons[fg_console].vt_mode.mode = VT_AUTO;
 444                 vt_cons[fg_console].vt_mode.waitv = 0;
 445                 vt_cons[fg_console].vt_mode.relsig = 0;
 446                 vt_cons[fg_console].vt_mode.acqsig = 0;
 447                 vt_cons[fg_console].vt_mode.frsig = 0;
 448                 vt_cons[fg_console].vt_pid = -1;
 449                 vt_cons[fg_console].vt_newvt = -1;
 450                 /*
 451                  * Fall through to normal (VT_AUTO) handling of the switch...
 452                  */
 453         }
 454 
 455         /*
 456          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 457          */
 458         if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
 459                 return;
 460 
 461         complete_change_console(new_console);
 462 }
 463 
 464 void wait_for_keypress(void)
     /*  */
 465 {
 466         sleep_on(&keypress_wait);
 467 }
 468 
 469 void copy_to_cooked(struct tty_struct * tty)
     /*  */
 470 {
 471         int c, special_flag;
 472         unsigned long flags;
 473 
 474         if (!tty) {
 475                 printk("copy_to_cooked: called with NULL tty\n");
 476                 return;
 477         }
 478         if (!tty->write) {
 479                 printk("copy_to_cooked: tty %d has null write routine\n",
 480                        tty->line);
 481         }
 482         while (1) {
 483                 /*
 484                  * Check to see how much room we have left in the
 485                  * secondary queue.  Send a throttle command or abort
 486                  * if necessary.
 487                  */
 488                 c = LEFT(&tty->secondary);
 489                 if (tty->throttle && (c < SQ_THRESHOLD_LW)
 490                     && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
 491                         tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
 492                 if (c == 0)
 493                         break;
 494                 save_flags(flags); cli();
 495                 if (tty->read_q.tail != tty->read_q.head) {
 496                         c = 0xff & tty->read_q.buf[tty->read_q.tail];
 497                         special_flag = !clear_bit(tty->read_q.tail,
 498                                                   &tty->readq_flags);
 499                         tty->read_q.tail = (tty->read_q.tail + 1) &
 500                                 (TTY_BUF_SIZE-1);
 501                         restore_flags(flags);
 502                 } else {
 503                         restore_flags(flags);
 504                         break;
 505                 }
 506                 if (special_flag) {
 507                         tty->char_error = c & 3;
 508                         continue;
 509                 }
 510                 if (tty->char_error) {
 511                         if (tty->char_error == TTY_BREAK) {
 512                                 tty->char_error = 0;
 513                                 if (I_IGNBRK(tty))
 514                                         continue;
 515                                 if (I_PARMRK(tty)) {
 516                                         put_tty_queue('\377', &tty->secondary);
 517                                         put_tty_queue('\0', &tty->secondary);
 518                                 }
 519                                 put_tty_queue('\0', &tty->secondary);
 520                                 continue;
 521                         }
 522                         /* If not a break, then a parity or frame error */
 523                         tty->char_error = 0;
 524                         if (I_IGNPAR(tty)) {
 525                                 continue;
 526                         }
 527                         if (I_PARMRK(tty)) {
 528                                 put_tty_queue('\377', &tty->secondary);
 529                                 put_tty_queue('\0', &tty->secondary);
 530                                 put_tty_queue(c, &tty->secondary);
 531                         } else
 532                                 put_tty_queue('\0', &tty->secondary);
 533                         continue;
 534                 }
 535                 if (I_STRP(tty))
 536                         c &= 0x7f;
 537                 else if (I_PARMRK(tty) && (c == '\377'))
 538                         put_tty_queue('\377', &tty->secondary);
 539                 if (c==13) {
 540                         if (I_CRNL(tty))
 541                                 c=10;
 542                         else if (I_NOCR(tty))
 543                                 continue;
 544                 } else if (c==10 && I_NLCR(tty))
 545                         c=13;
 546                 if (I_UCLC(tty))
 547                         c=tolower(c);
 548                 if (c == __DISABLED_CHAR)
 549                         tty->lnext = 1;
 550                 if (L_CANON(tty) && !tty->lnext) {
 551                         if (c == KILL_CHAR(tty) || c == WERASE_CHAR(tty)) {
 552                                 int seen_alnums =
 553                                   (c == WERASE_CHAR(tty)) ? 0 : -1;
 554 
 555                                 /* deal with killing the input line */
 556                                 while(!(EMPTY(&tty->secondary) ||
 557                                         (c=LAST(&tty->secondary))==10 ||
 558                                         ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 559                                          (c==EOF_CHAR(tty))))) {
 560                                         /* if killing just a word, kill all
 561                                            non-alnum chars, then all alnum
 562                                            chars.  */
 563                                         if (seen_alnums >= 0) {
 564                                                 if (isalnum(c))
 565                                                         seen_alnums++;
 566                                                 else if (seen_alnums)
 567                                                         break;
 568                                         }
 569                                         if (L_ECHO(tty)) {
 570                                                 if (c<32) {
 571                                                         put_tty_queue('\b', &tty->write_q);
 572                                                         put_tty_queue(' ', &tty->write_q);
 573                                                         put_tty_queue('\b',&tty->write_q);
 574                                                 }
 575                                                 put_tty_queue('\b',&tty->write_q);
 576                                                 put_tty_queue(' ',&tty->write_q);
 577                                                 put_tty_queue('\b',&tty->write_q);
 578                                         }
 579                                         DEC(tty->secondary.head);
 580                                 }
 581                                 continue;
 582                         }
 583                         if (c == ERASE_CHAR(tty)) {
 584                                 if (EMPTY(&tty->secondary) ||
 585                                    (c=LAST(&tty->secondary))==10 ||
 586                                    ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 587                                     (c==EOF_CHAR(tty))))
 588                                         continue;
 589                                 if (L_ECHO(tty)) {
 590                                         if (c<32) {
 591                                                 put_tty_queue('\b',&tty->write_q);
 592                                                 put_tty_queue(' ',&tty->write_q);
 593                                                 put_tty_queue('\b',&tty->write_q);
 594                                         }
 595                                         put_tty_queue('\b',&tty->write_q);
 596                                         put_tty_queue(' ',&tty->write_q);
 597                                         put_tty_queue('\b',&tty->write_q);
 598                                 }
 599                                 DEC(tty->secondary.head);
 600                                 continue;
 601                         }
 602                         if (c == LNEXT_CHAR(tty)) {
 603                                 tty->lnext = 1;
 604                                 if (L_ECHO(tty)) {
 605                                         put_tty_queue('^',&tty->write_q);
 606                                         put_tty_queue('\b',&tty->write_q);
 607                                 }
 608                                 continue;
 609                         }
 610                 }
 611                 if (I_IXON(tty) && !tty->lnext) {
 612                         if (c == STOP_CHAR(tty)) {
 613                                 tty->status_changed = 1;
 614                                 tty->ctrl_status |= TIOCPKT_STOP;
 615                                 tty->stopped=1;
 616                                 if (IS_A_CONSOLE(tty->line)) {
 617                                         set_vc_kbd_flag(kbd_table + fg_console, VC_SCROLLOCK);
 618                                         set_leds();
 619                                 }
 620                                 continue;
 621                         }
 622                         if (((I_IXANY(tty)) && tty->stopped) ||
 623                             (c == START_CHAR(tty))) {
 624                                 tty->status_changed = 1;
 625                                 tty->ctrl_status |= TIOCPKT_START;
 626                                 tty->stopped=0;
 627                                 if (IS_A_CONSOLE(tty->line)) {
 628                                         clr_vc_kbd_flag(kbd_table + fg_console, VC_SCROLLOCK);
 629                                         set_leds();
 630                                 }
 631                                 continue;
 632                         }
 633                 }
 634                 if (L_ISIG(tty) && !tty->lnext) {
 635                         if (c == INTR_CHAR(tty)) {
 636                                 kill_pg(tty->pgrp, SIGINT, 1);
 637                                 flush_input(tty);
 638                                 continue;
 639                         }
 640                         if (c == QUIT_CHAR(tty)) {
 641                                 kill_pg(tty->pgrp, SIGQUIT, 1);
 642                                 flush_input(tty);
 643                                 continue;
 644                         }
 645                         if (c == SUSPEND_CHAR(tty)) {
 646                                 if (!is_orphaned_pgrp(tty->pgrp)) {
 647                                         kill_pg(tty->pgrp, SIGTSTP, 1);
 648                                         flush_input(tty);
 649                                 }
 650                                 continue;
 651                         }
 652                 }
 653                 if (c==10 || (EOF_CHAR(tty) != __DISABLED_CHAR &&
 654                     c==EOF_CHAR(tty)))
 655                         tty->secondary.data++;
 656                 if ((c==10) && (L_ECHO(tty) || (L_CANON(tty) && L_ECHONL(tty)))) {
 657                         put_tty_queue('\n',&tty->write_q);
 658                         put_tty_queue('\r',&tty->write_q);
 659                 } else if (L_ECHO(tty)) {
 660                         if (c<32 && L_ECHOCTL(tty)) {
 661                                 put_tty_queue('^',&tty->write_q);
 662                                 put_tty_queue(c+'A'-1, &tty->write_q);
 663                                 if (EOF_CHAR(tty) != __DISABLED_CHAR &&
 664                                     c==EOF_CHAR(tty) && !tty->lnext) {
 665                                         put_tty_queue('\b',&tty->write_q);
 666                                         put_tty_queue('\b',&tty->write_q);
 667                                 }
 668                         } else
 669                                 put_tty_queue(c, &tty->write_q);
 670                 }
 671                 tty->lnext = 0;
 672                 put_tty_queue(c, &tty->secondary);
 673         }
 674         TTY_WRITE_FLUSH(tty);
 675         if (!EMPTY(&tty->secondary))
 676                 wake_up_interruptible(&tty->secondary.proc_list);
 677         if (tty->write_q.proc_list && LEFT(&tty->write_q) > TTY_BUF_SIZE/2)
 678                 wake_up_interruptible(&tty->write_q.proc_list);
 679         if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
 680             && !clear_bit(TTY_RQ_THROTTLED, &tty->flags))
 681                 tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
 682         if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 683             && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 684                 tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 685 }
 686 
 687 int is_ignored(int sig)
     /*  */
 688 {
 689         return ((current->blocked & (1<<(sig-1))) ||
 690                 (current->sigaction[sig-1].sa_handler == SIG_IGN));
 691 }
 692 
 693 static int available_canon_input(struct tty_struct *);
 694 static void __wait_for_canon_input(struct file * file, struct tty_struct *);
 695 
 696 static void wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 697 {
 698         if (!available_canon_input(tty)) {
 699                 if (current->signal & ~current->blocked)
 700                         return;
 701                 __wait_for_canon_input(file, tty);
 702         }
 703 }
 704 
 705 static int read_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 706 {
 707         struct wait_queue wait = { current, NULL };
 708         int c;
 709         char * b=buf;
 710         int minimum,time;
 711 
 712         if (L_CANON(tty))
 713                 minimum = time = current->timeout = 0;
 714         else {
 715                 time = 10L*tty->termios->c_cc[VTIME];
 716                 minimum = tty->termios->c_cc[VMIN];
 717                 if (minimum)
 718                         current->timeout = 0xffffffff;
 719                 else {
 720                         if (time)
 721                                 current->timeout = time + jiffies;
 722                         else
 723                                 current->timeout = 0;
 724                         time = 0;
 725                         minimum = 1;
 726                 }
 727         }
 728         if (file->f_flags & O_NONBLOCK) {
 729                 time = current->timeout = 0;
 730                 if (L_CANON(tty) && !available_canon_input(tty))
 731                                 return -EAGAIN;
 732         } else if (L_CANON(tty)) {
 733                 wait_for_canon_input(file, tty);
 734                 if (current->signal & ~current->blocked)
 735                         return -ERESTARTSYS;
 736         }
 737         if (minimum>nr)
 738                 minimum = nr;
 739 
 740         /* deal with packet mode:  First test for status change */
 741         if (tty->packet && tty->link && tty->link->status_changed) {
 742                 put_fs_byte (tty->link->ctrl_status, b);
 743                 tty->link->status_changed = 0;
 744                 return 1;
 745         }
 746           
 747         /* now bump the buffer up one. */
 748         if (tty->packet) {
 749                 put_fs_byte (0,b++);
 750                 nr--;
 751                 /* this really shouldn't happen, but we need to 
 752                 put it here. */
 753                 if (nr == 0)
 754                         return 1;
 755         }
 756         add_wait_queue(&tty->secondary.proc_list, &wait);
 757         while (nr>0) {
 758                 if (tty_hung_up_p(file)) {
 759                         file->f_flags &= ~O_NONBLOCK;
 760                         break;  /* force read() to return 0 */
 761                 }
 762                 TTY_READ_FLUSH(tty);
 763                 if (tty->link)
 764                         TTY_WRITE_FLUSH(tty->link);
 765                 while (nr > 0 && ((c = get_tty_queue(&tty->secondary)) >= 0)) {
 766                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 767                              c==EOF_CHAR(tty)) || c==10)
 768                                 tty->secondary.data--;
 769                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 770                              c==EOF_CHAR(tty)) && L_CANON(tty))
 771                                 break;
 772                         put_fs_byte(c,b++);
 773                         nr--;
 774                         if (time)
 775                                 current->timeout = time+jiffies;
 776                         if (c==10 && L_CANON(tty))
 777                                 break;
 778                 };
 779                 wake_up_interruptible(&tty->read_q.proc_list);
 780                 /*
 781                  * If there is enough space in the secondary queue
 782                  * now, let the low-level driver know.
 783                  */
 784                 if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 785                     && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 786                         tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 787                 if (b-buf >= minimum || !current->timeout)
 788                         break;
 789                 if (current->signal & ~current->blocked) 
 790                         break;
 791                 if (tty->link) {
 792                         if (IS_A_PTY_MASTER(tty->line)) {
 793                                 if ((tty->flags & (1 << TTY_SLAVE_OPENED))
 794                                     && tty->link->count <= 1)
 795                                         break;
 796                         } else {
 797                                 if (!tty->link->count)
 798                                         break;
 799                         }
 800                 }
 801                 TTY_READ_FLUSH(tty);
 802                 if (tty->link)
 803                         TTY_WRITE_FLUSH(tty->link);
 804                 if (!EMPTY(&tty->secondary))
 805                         continue;
 806                 current->state = TASK_INTERRUPTIBLE;
 807                 if (EMPTY(&tty->secondary))
 808                         schedule();
 809                 current->state = TASK_RUNNING;
 810         }
 811         remove_wait_queue(&tty->secondary.proc_list, &wait);
 812         TTY_READ_FLUSH(tty);
 813         if (tty->link && tty->link->write)
 814                 TTY_WRITE_FLUSH(tty->link);
 815         current->timeout = 0;
 816 
 817         /* packet mode sticks in an extra 0.  If that's all we've got,
 818            we should count it a zero bytes. */
 819         if (tty->packet) {
 820                 if ((b-buf) > 1)
 821                         return b-buf;
 822         } else {
 823                 if (b-buf)
 824                         return b-buf;
 825         }
 826 
 827         if (current->signal & ~current->blocked)
 828                 return -ERESTARTSYS;
 829         if (file->f_flags & O_NONBLOCK)
 830                 return -EAGAIN;
 831         if (IS_A_PTY_MASTER(tty->line))
 832                 return -EIO;
 833         return 0;
 834 }
 835 
 836 static void __wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 837 {
 838         struct wait_queue wait = { current, NULL };
 839 
 840         add_wait_queue(&tty->secondary.proc_list, &wait);
 841         while (1) {
 842                 current->state = TASK_INTERRUPTIBLE;
 843                 if (available_canon_input(tty))
 844                         break;
 845                 if (current->signal & ~current->blocked)
 846                         break;
 847                 if (tty_hung_up_p(file))
 848                         break;
 849                 schedule();
 850         }
 851         current->state = TASK_RUNNING;
 852         remove_wait_queue(&tty->secondary.proc_list, &wait);
 853 }
 854 
 855 static int available_canon_input(struct tty_struct * tty)
     /*  */
 856 {
 857         TTY_READ_FLUSH(tty);
 858         if (tty->link)
 859                 if (tty->link->count)
 860                         TTY_WRITE_FLUSH(tty->link);
 861                 else
 862                         return 1;
 863         if (FULL(&tty->read_q))
 864                 return 1;
 865         if (tty->secondary.data)
 866                 return 1;
 867         return 0;
 868 }
 869 
 870 static int write_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 871 {
 872         struct wait_queue wait = { current, NULL };
 873         char c, *b=buf;
 874 
 875         if (nr < 0)
 876                 return -EINVAL;
 877         if (!nr)
 878                 return 0;
 879         add_wait_queue(&tty->write_q.proc_list, &wait);
 880         while (nr>0) {
 881                 if (current->signal & ~current->blocked)
 882                         break;
 883                 if (tty_hung_up_p(file))
 884                         break;
 885                 if (tty->link && !tty->link->count) {
 886                         send_sig(SIGPIPE,current,0);
 887                         break;
 888                 }
 889                 current->state = TASK_INTERRUPTIBLE;
 890                 if (FULL(&tty->write_q)) {
 891                         TTY_WRITE_FLUSH(tty);
 892                         if (FULL(&tty->write_q))
 893                                 schedule();
 894                         current->state = TASK_RUNNING;
 895                         continue;
 896                 }
 897                 current->state = TASK_RUNNING;
 898                 while (nr>0 && !FULL(&tty->write_q)) {
 899                         c=get_fs_byte(b);
 900                         if (O_POST(tty)) {
 901                                 switch (c) {
 902                                         case '\n':
 903                                                 if (O_NLRET(tty)) {
 904                                                         tty->column = 0;
 905                                                 }
 906                                                 if (O_NLCR(tty)) {
 907                                                         if (!set_bit(TTY_CR_PENDING,&tty->flags)) {
 908                                                                 c = '\r';
 909                                                                 tty->column = 0;
 910                                                                 b--; nr++;
 911                                                         } else {
 912                                                                 clear_bit(TTY_CR_PENDING,&tty->flags);
 913                                                         }
 914                                                 }
 915                                                 break;
 916                                         case '\r':
 917                                                 if (O_NOCR(tty) && tty->column == 0) {
 918                                                         b++; nr--;
 919                                                         continue;
 920                                                 }
 921                                                 if (O_CRNL(tty)) {
 922                                                         c = '\n';
 923                                                         if (O_NLRET(tty))
 924                                                                 tty->column = 0;
 925                                                         break;
 926                                                 }
 927                                                 tty->column = 0;
 928                                                 break;
 929                                         case '\t':
 930                                                 if (O_TABDLY(tty) == XTABS) {
 931                                                         c = ' ';
 932                                                         tty->column++;
 933                                                         if (tty->column % 8 != 0) {
 934                                                                 b--; nr++;
 935                                                         }
 936                                                 }
 937                                                 break;
 938                                         case '\b':
 939                                                 tty->column--;
 940                                                 break;
 941                                         default:
 942                                                 if (O_LCUC(tty))
 943                                                         c = toupper(c);
 944                                                 tty->column++;
 945                                                 break;
 946                                 }
 947                         }
 948                         b++; nr--;
 949                         put_tty_queue(c,&tty->write_q);
 950                 }
 951                 if (need_resched)
 952                         schedule();
 953         }
 954         remove_wait_queue(&tty->write_q.proc_list, &wait);
 955         TTY_WRITE_FLUSH(tty);
 956         if (b-buf)
 957                 return b-buf;
 958         if (tty->link && !tty->link->count)
 959                 return -EPIPE;
 960         if (current->signal & ~current->blocked)
 961                 return -ERESTARTSYS;
 962         return 0;
 963 }
 964 
 965 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 966 {
 967         int i, dev;
 968         struct tty_struct * tty;
 969 
 970         dev = file->f_rdev;
 971         if (MAJOR(dev) != 4) {
 972                 printk("tty_read: bad pseudo-major nr #%d\n", MAJOR(dev));
 973                 return -EINVAL;
 974         }
 975         dev = MINOR(dev);
 976         tty = TTY_TABLE(dev);
 977         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 978                 return -EIO;
 979         if ((inode->i_rdev != 0x0400) && /* don't stop on /dev/console */
 980             (tty->pgrp > 0) &&
 981             (current->tty == dev) &&
 982             (tty->pgrp != current->pgrp))
 983                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 984                         return -EIO;
 985                 else {
 986                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 987                         return -ERESTARTSYS;
 988                 }
 989         if (ldiscs[tty->disc].read)
 990                 i = (ldiscs[tty->disc].read)(tty,file,buf,count);
 991         else
 992                 i = -EIO;
 993         if (i > 0)
 994                 inode->i_atime = CURRENT_TIME;
 995         return i;
 996 }
 997 
 998 static int tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 999 {
1000         int dev, i, is_console;
1001         struct tty_struct * tty;
1002 
1003         dev = file->f_rdev;
1004         is_console = (inode->i_rdev == 0x0400);
1005         if (MAJOR(dev) != 4) {
1006                 printk("tty_write: pseudo-major != 4\n");
1007                 return -EINVAL;
1008         }
1009         dev = MINOR(dev);
1010         if (is_console && redirect)
1011                 tty = redirect;
1012         else
1013                 tty = TTY_TABLE(dev);
1014         if (!tty || !tty->write || (tty->flags & (1 << TTY_IO_ERROR)))
1015                 return -EIO;
1016         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
1017             (current->tty == dev) && (tty->pgrp != current->pgrp)) {
1018                 if (is_orphaned_pgrp(current->pgrp))
1019                         return -EIO;
1020                 if (!is_ignored(SIGTTOU)) {
1021                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
1022                         return -ERESTARTSYS;
1023                 }
1024         }
1025         if (ldiscs[tty->disc].write)
1026                 i = (ldiscs[tty->disc].write)(tty,file,buf,count);
1027         else
1028                 i = -EIO;
1029         if (i > 0)
1030                 inode->i_mtime = CURRENT_TIME;
1031         return i;
1032 }
1033 
1034 /*
1035  * This is so ripe with races that you should *really* not touch this
1036  * unless you know exactly what you are doing. All the changes have to be
1037  * made atomically, or there may be incorrect pointers all over the place.
1038  */
1039 static int init_dev(int dev)
     /*  */
1040 {
1041         struct tty_struct *tty, *o_tty;
1042         struct termios *tp, *o_tp;
1043         int retval;
1044         int o_dev;
1045 
1046         o_dev = PTY_OTHER(dev);
1047         tty = o_tty = NULL;
1048         tp = o_tp = NULL;
1049 repeat:
1050         retval = -EAGAIN;
1051         if (IS_A_PTY_MASTER(dev) && tty_table[dev] && tty_table[dev]->count)
1052                 goto end_init;
1053         retval = -ENOMEM;
1054         if (!tty_table[dev] && !tty) {
1055                 tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
1056                 if (!tty)
1057                         goto end_init;
1058                 initialize_tty_struct(dev, tty);
1059                 goto repeat;
1060         }
1061         if (!tty_termios[dev] && !tp) {
1062                 tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
1063                 if (!tp)
1064                         goto end_init;
1065                 initialize_termios(dev, tp);
1066                 goto repeat;
1067         }
1068         if (IS_A_PTY(dev)) {
1069                 if (!tty_table[o_dev] && !o_tty) {
1070                         o_tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
1071                         if (!o_tty)
1072                                 goto end_init;
1073                         initialize_tty_struct(o_dev, o_tty);
1074                         goto repeat;
1075                 }
1076                 if (!tty_termios[o_dev] && !o_tp) {
1077                         o_tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
1078                         if (!o_tp)
1079                                 goto end_init;
1080                         initialize_termios(o_dev, o_tp);
1081                         goto repeat;
1082                 }
1083         }
1084         /* Now we have allocated all the structures: update all the pointers.. */
1085         if (!tty_termios[dev]) {
1086                 tty_termios[dev] = tp;
1087                 tp = NULL;
1088         }
1089         if (!tty_table[dev]) {
1090                 tty->termios = tty_termios[dev];
1091                 tty_table[dev] = tty;
1092                 tty = NULL;
1093         }
1094         if (IS_A_PTY(dev)) {
1095                 if (!tty_termios[o_dev]) {
1096                         tty_termios[o_dev] = o_tp;
1097                         o_tp = NULL;
1098                 }
1099                 if (!tty_table[o_dev]) {
1100                         o_tty->termios = tty_termios[o_dev];
1101                         tty_table[o_dev] = o_tty;
1102                         o_tty = NULL;
1103                 }
1104                 tty_table[dev]->link = tty_table[o_dev];
1105                 tty_table[o_dev]->link = tty_table[dev];
1106         }
1107         tty_table[dev]->count++;
1108         if (IS_A_PTY_MASTER(dev))
1109                 tty_table[o_dev]->count++;
1110         retval = 0;
1111 end_init:
1112         if (tty)
1113                 free_page((unsigned long) tty);
1114         if (o_tty)
1115                 free_page((unsigned long) o_tty);
1116         if (tp)
1117                 kfree_s(tp, sizeof(struct termios));
1118         if (o_tp)
1119                 kfree_s(o_tp, sizeof(struct termios));
1120         return retval;
1121 }
1122 
1123 /*
1124  * Even releasing the tty structures is a tricky business.. We have
1125  * to be very careful that the structures are all released at the
1126  * same time, as interrupts might otherwise get the wrong pointers.
1127  */
1128 static void release_dev(int dev, struct file * filp)
     /*  */
1129 {
1130         struct tty_struct *tty, *o_tty;
1131         struct termios *tp, *o_tp;
1132         struct task_struct **p;
1133 
1134         tty = tty_table[dev];
1135         tp = tty_termios[dev];
1136         o_tty = NULL;
1137         o_tp = NULL;
1138         if (!tty) {
1139                 printk("release_dev: tty_table[%d] was NULL\n", dev);
1140                 return;
1141         }
1142         if (!tp) {
1143                 printk("release_dev: tty_termios[%d] was NULL\n", dev);
1144                 return;
1145         }
1146         if (IS_A_PTY(dev)) {
1147                 o_tty = tty_table[PTY_OTHER(dev)];
1148                 o_tp = tty_termios[PTY_OTHER(dev)];
1149                 if (!o_tty) {
1150                         printk("release_dev: pty pair(%d) was NULL\n", dev);
1151                         return;
1152                 }
1153                 if (!o_tp) {
1154                         printk("release_dev: pty pair(%d) termios was NULL\n", dev);
1155                         return;
1156                 }
1157                 if (tty->link != o_tty || o_tty->link != tty) {
1158                         printk("release_dev: bad pty pointers\n");
1159                         return;
1160                 }
1161         }
1162         tty->write_data_cnt = 0; /* Clear out pending trash */
1163         if (tty->close)
1164                 tty->close(tty, filp);
1165         if (IS_A_PTY_MASTER(dev)) {
1166                 if (--tty->link->count < 0) {
1167                         printk("release_dev: bad tty slave count (dev = %d): %d\n",
1168                                dev, tty->count);
1169                         tty->link->count = 0;
1170                 }
1171         }
1172         if (--tty->count < 0) {
1173                 printk("release_dev: bad tty_table[%d]->count: %d\n",
1174                        dev, tty->count);
1175                 tty->count = 0;
1176         }
1177         if (tty->count)
1178                 return;
1179 
1180         /*
1181          * Make sure there aren't any processes that still think this
1182          * tty is their controlling tty.
1183          */
1184         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1185                 if ((*p) && (*p)->tty == tty->line)
1186                 (*p)->tty = -1;
1187         }
1188 
1189         if (ldiscs[tty->disc].close != NULL)
1190                 ldiscs[tty->disc].close(tty);
1191 
1192         if (o_tty) {
1193                 if (o_tty->count)
1194                         return;
1195                 else {
1196                         tty_table[PTY_OTHER(dev)] = NULL;
1197                         tty_termios[PTY_OTHER(dev)] = NULL;
1198                 }
1199         }
1200         tty_table[dev] = NULL;
1201         if (IS_A_PTY(dev)) {
1202                 tty_termios[dev] = NULL;
1203                 kfree_s(tp, sizeof(struct termios));
1204         }
1205         if (tty == redirect || o_tty == redirect)
1206                 redirect = NULL;
1207         free_page((unsigned long) tty);
1208         if (o_tty)
1209                 free_page((unsigned long) o_tty);
1210         if (o_tp)
1211                 kfree_s(o_tp, sizeof(struct termios));
1212 }
1213 
1214 /*
1215  * tty_open and tty_release keep up the tty count that contains the
1216  * number of opens done on a tty. We cannot use the inode-count, as
1217  * different inodes might point to the same tty.
1218  *
1219  * Open-counting is needed for pty masters, as well as for keeping
1220  * track of serial lines: DTR is dropped when the last close happens.
1221  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1222  *
1223  * The termios state of a pty is reset on first open so that
1224  * settings don't persist across reuse.
1225  */
1226 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1227 {
1228         struct tty_struct *tty;
1229         int major, minor;
1230         int noctty, retval;
1231 
1232         minor = MINOR(inode->i_rdev);
1233         major = MAJOR(inode->i_rdev);
1234         noctty = filp->f_flags & O_NOCTTY;
1235         if (major == 5) {
1236                 if (!minor) {
1237                         major = 4;
1238                         minor = current->tty;
1239                 }
1240                 noctty = 1;
1241         } else if (major == 4) {
1242                 if (!minor) {
1243                         minor = fg_console + 1;
1244                         noctty = 1;
1245                 }
1246         } else {
1247                 printk("Bad major #%d in tty_open\n", MAJOR(inode->i_rdev));
1248                 return -ENODEV;
1249         }
1250         if (minor <= 0)
1251                 return -ENXIO;
1252         if (IS_A_PTY_MASTER(minor))
1253                 noctty = 1;
1254         filp->f_rdev = (major << 8) | minor;
1255         retval = init_dev(minor);
1256         if (retval)
1257                 return retval;
1258         tty = tty_table[minor];
1259 
1260         /* clean up the packet stuff. */
1261         /*
1262          *  Why is this not done in init_dev?  Right here, if another 
1263          * process opens up a tty in packet mode, all the packet 
1264          * variables get cleared.  Come to think of it, is anything 
1265          * using the packet mode at all???  - Ted, 1/27/93
1266          */
1267         tty->status_changed = 0;
1268         tty->ctrl_status = 0;
1269         tty->packet = 0;
1270 
1271         if (tty->open) {
1272                 retval = tty->open(tty, filp);
1273         } else {
1274                 retval = -ENODEV;
1275         }
1276         if (retval) {
1277                 release_dev(minor, filp);
1278                 return retval;
1279         }
1280         if (!noctty &&
1281             current->leader &&
1282             current->tty<0 &&
1283             tty->session==0) {
1284                 current->tty = minor;
1285                 tty->session = current->session;
1286                 tty->pgrp = current->pgrp;
1287         }
1288         filp->f_rdev = 0x0400 | minor; /* Set it to something normal */
1289         return 0;
1290 }
1291 
1292 /*
1293  * Note that releasing a pty master also releases the child, so
1294  * we have to make the redirection checks after that and on both
1295  * sides of a pty.
1296  */
1297 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1298 {
1299         int dev;
1300 
1301         dev = filp->f_rdev;
1302         if (MAJOR(dev) != 4) {
1303                 printk("tty_release: tty pseudo-major != 4\n");
1304                 return;
1305         }
1306         dev = MINOR(filp->f_rdev);
1307         if (!dev) {
1308                 printk("tty_release: bad f_rdev\n");
1309                 return;
1310         }
1311         release_dev(dev, filp);
1312 }
1313 
1314 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1315 {
1316         int dev;
1317         struct tty_struct * tty;
1318 
1319         dev = filp->f_rdev;
1320         if (MAJOR(dev) != 4) {
1321                 printk("tty_select: tty pseudo-major != 4\n");
1322                 return 0;
1323         }
1324         dev = MINOR(filp->f_rdev);
1325         tty = TTY_TABLE(dev);
1326         if (!tty) {
1327                 printk("tty_select: tty struct for dev %d was NULL\n", dev);
1328                 return 0;
1329         }
1330         switch (sel_type) {
1331                 case SEL_IN:
1332                         if (L_CANON(tty)) {
1333                                 if (available_canon_input(tty))
1334                                         return 1;
1335                         } else if (!EMPTY(&tty->secondary))
1336                                 return 1;
1337                         if (tty->link) {
1338                                 if (IS_A_PTY_MASTER(tty->line)) {
1339                                         if ((tty->flags & (1 << TTY_SLAVE_OPENED))
1340                                             && tty->link->count <= 1)
1341                                                 return 1;
1342                                 } else {
1343                                         if (!tty->link->count)
1344                                                 return 1;
1345                                 }
1346                         }
1347 
1348                         /* see if the status byte can be read. */
1349                         if (tty->packet && tty->link &&
1350                             tty->link->status_changed)
1351                                 return 1;
1352 
1353                         select_wait(&tty->secondary.proc_list, wait);
1354                         return 0;
1355                 case SEL_OUT:
1356                         if (!FULL(&tty->write_q))
1357                                 return 1;
1358                         select_wait(&tty->write_q.proc_list, wait);
1359                         return 0;
1360                 case SEL_EX:
1361                         if (tty->link) {
1362                                 if (IS_A_PTY_MASTER(tty->line)) {
1363                                         if ((tty->flags & (1 << TTY_SLAVE_OPENED))
1364                                             && tty->link->count <= 1)
1365                                                 return 1;
1366                                 } else {
1367                                         if (!tty->link->count)
1368                                                 return 1;
1369                                 }
1370                         }
1371                         return 0;
1372         }
1373         return 0;
1374 }
1375 
1376 /*
1377  * This implements the "Secure Attention Key" ---  the idea is to
1378  * prevent trojan horses by killing all processes associated with this
1379  * tty when the user hits the "Secure Attention Key".  Required for
1380  * super-paranoid applications --- see the Orange Book for more details.
1381  * 
1382  * This code could be nicer; ideally it should send a HUP, wait a few
1383  * seconds, then send a INT, and then a KILL signal.  But you then
1384  * have to coordinate with the init process, since all processes associated
1385  * with the current tty must be dead before the new getty is allowed
1386  * to spawn.
1387  */
1388 void do_SAK( struct tty_struct *tty)
     /*  */
1389 {
1390         struct task_struct **p;
1391         int line = tty->line;
1392         int session = tty->session;
1393         int             i;
1394         struct file     *filp;
1395         
1396         flush_input(tty);
1397         flush_output(tty);
1398         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1399                 if (!(*p))
1400                         continue;
1401                 if (((*p)->tty == line) ||
1402                     ((session > 0) && ((*p)->session == session)))
1403                         send_sig(SIGKILL, *p, 1);
1404                 else {
1405                         for (i=0; i < NR_FILE; i++) {
1406                                 filp = (*p)->filp[i];
1407                                 if (filp && (filp->f_op == &tty_fops) &&
1408                                     (MINOR(filp->f_rdev) == line)) {
1409                                         send_sig(SIGKILL, *p, 1);
1410                                         break;
1411                                 }
1412                         }
1413                 }
1414         }
1415 }
1416 
1417 /*
1418  * This routine allows a kernel routine to send a large chunk of data
1419  * to a particular tty; if all of the data can be queued up for ouput
1420  * immediately, tty_write_data() will return 0.  If, however, not all
1421  * of the data can be immediately queued for delivery, the number of
1422  * bytes left to be queued up will be returned, and the rest of the
1423  * data will be queued up when there is room.  The callback function
1424  * will be called (with the argument callarg) when the last of the
1425  * data is finally in the queue.
1426  *
1427  * Note that the callback routine will _not_ be called if all of the
1428  * data could be queued immediately.  This is to avoid a problem with
1429  * the kernel stack getting too deep, which might happen if the
1430  * callback routine calls tty_write_data with itself as an argument.
1431  */
1432 int tty_write_data(struct tty_struct *tty, char *bufp, int buflen,
     /*  */
1433                     void (*callback)(void * data), void * callarg)
1434 {
1435         int head, tail, count;
1436         unsigned long flags;
1437         char *p;
1438 
1439 #define VLEFT ((tail-head-1)&(TTY_BUF_SIZE-1))
1440 
1441         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
1442         if (tty->write_data_cnt) {
1443                 __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1444                 return -EBUSY;
1445         }
1446 
1447         head = tty->write_q.head;
1448         tail = tty->write_q.tail;
1449         count = buflen;
1450         p = bufp;
1451 
1452         while (count && VLEFT > 0) {
1453                 tty->write_q.buf[head++] = *p++;
1454                 head &= TTY_BUF_SIZE-1;
1455                 count--;
1456         }
1457         tty->write_q.head = head;
1458         if (count) {
1459                 tty->write_data_cnt = count;
1460                 tty->write_data_ptr = p;
1461                 tty->write_data_callback = callback;
1462                 tty->write_data_arg = callarg;
1463         }
1464         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1465         tty->write(tty);
1466         return count;
1467 }
1468 
1469 /*
1470  * This routine routine is called after an interrupt has drained a
1471  * tty's write queue, so that there is more space for data waiting to
1472  * be sent in tty->write_data_ptr.
1473  *
1474  * tty_check_write[8] is a bitstring which indicates which ttys
1475  * needs to be processed.
1476  */
1477 void tty_bh_routine(void * unused)
     /*  */
1478 {
1479         int     i, j, line, mask;
1480         int     head, tail, count;
1481         unsigned char * p;
1482         struct tty_struct * tty;
1483 
1484         for (i = 0, line = 0; i < MAX_TTYS / 32; i++) {
1485                 if (!tty_check_write[i]) {
1486                         line += 32;
1487                         continue;
1488                 }
1489                 for (j=0, mask=0; j < 32; j++, line++, mask <<= 1) {
1490                         if (!clear_bit(j, &tty_check_write[i])) {
1491                                 tty = tty_table[line];
1492                                 if (!tty || !tty->write_data_cnt)
1493                                         continue;
1494                                 cli();
1495                                 head = tty->write_q.head;
1496                                 tail = tty->write_q.tail;
1497                                 count = tty->write_data_cnt;
1498                                 p = tty->write_data_ptr;
1499 
1500                                 while (count && VLEFT > 0) {
1501                                         tty->write_q.buf[head++] = *p++;
1502                                         head &= TTY_BUF_SIZE-1;
1503                                         count--;
1504                                 }
1505                                 tty->write_q.head = head;
1506                                 tty->write_data_ptr = p;
1507                                 tty->write_data_cnt = count;
1508                                 sti();
1509                                 if (!count)
1510                                         (tty->write_data_callback)
1511                                                 (tty->write_data_arg);
1512                         }
1513                 }
1514         }
1515         
1516 }
1517 
1518 /*
1519  * This subroutine initializes a tty structure.  We have to set up
1520  * things correctly for each different type of tty.
1521  */
1522 static void initialize_tty_struct(int line, struct tty_struct *tty)
     /*  */
1523 {
1524         memset(tty, 0, sizeof(struct tty_struct));
1525         tty->line = line;
1526         tty->disc = N_TTY;
1527         tty->pgrp = -1;
1528         tty->winsize.ws_row = 0;
1529         tty->winsize.ws_col = 0;
1530         if (IS_A_CONSOLE(line)) {
1531                 tty->open = con_open;
1532                 tty->winsize.ws_row = video_num_lines;
1533                 tty->winsize.ws_col = video_num_columns;
1534         } else if IS_A_SERIAL(line) {
1535                 tty->open = rs_open;
1536         } else if IS_A_PTY(line) {
1537                 tty->open = pty_open;
1538         }
1539 }
1540 
1541 static void initialize_termios(int line, struct termios * tp)
     /*  */
1542 {
1543         memset(tp, 0, sizeof(struct termios));
1544         memcpy(tp->c_cc, INIT_C_CC, NCCS);
1545         if (IS_A_CONSOLE(line)) {
1546                 tp->c_iflag = ICRNL | IXON;
1547                 tp->c_oflag = OPOST | ONLCR;
1548                 tp->c_cflag = B38400 | CS8 | CREAD;
1549                 tp->c_lflag = ISIG | ICANON | ECHO |
1550                         ECHOCTL | ECHOKE;
1551         } else if (IS_A_SERIAL(line)) {
1552                 tp->c_cflag = B2400 | CS8 | CREAD | HUPCL | CLOCAL;
1553                 tp->c_oflag = OPOST | ONLCR | XTABS;
1554         } else if (IS_A_PTY_MASTER(line)) {
1555                 tp->c_cflag = B9600 | CS8 | CREAD;
1556         } else if (IS_A_PTY_SLAVE(line)) {
1557                 tp->c_iflag = ICRNL | IXON;
1558                 tp->c_oflag = OPOST | ONLCR;
1559                 tp->c_cflag = B38400 | CS8 | CREAD;
1560                 tp->c_lflag = ISIG | ICANON | ECHO |
1561                         ECHOCTL | ECHOKE;
1562         }
1563 }
1564 
1565 static struct tty_ldisc tty_ldisc_N_TTY = {
1566         0,                      /* flags */
1567         NULL,                   /* open */
1568         NULL,                   /* close */
1569         read_chan,              /* read */
1570         write_chan,             /* write */
1571         NULL,                   /* ioctl */
1572         copy_to_cooked          /* handler */
1573 };
1574 
1575         
1576 long tty_init(long kmem_start)
     /*  */
1577 {
1578         int i;
1579 
1580         if (sizeof(struct tty_struct) > 4096)
1581                 panic("size of tty structure > 4096!");
1582         if (register_chrdev(4,"tty",&tty_fops))
1583                 panic("unable to get major 4 for tty device");
1584         if (register_chrdev(5,"tty",&tty_fops))
1585                 panic("unable to get major 5 for tty device");
1586         for (i=0 ; i< MAX_TTYS ; i++) {
1587                 tty_table[i] =  0;
1588                 tty_termios[i] = 0;
1589         }
1590         memset(tty_check_write, 0, sizeof(tty_check_write));
1591         bh_base[TTY_BH].routine = tty_bh_routine;
1592 
1593         /* Setup the default TTY line discipline. */
1594         memset(ldiscs, 0, sizeof(ldiscs));
1595         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1596 
1597         kmem_start = kbd_init(kmem_start);
1598         kmem_start = con_init(kmem_start);
1599         kmem_start = rs_init(kmem_start);
1600         return kmem_start;
1601 }
/* */
root/kernel/chr_drv/tty_io.c

DEFINITIONS
