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         struct task_struct **p;
 217         int dev;
 218 
 219         if (!tty)
 220                 return;
 221         dev = 0x0400 + tty->line;
 222         filp = file_table + NR_FILE;
 223         while (filp-- > file_table) {
 224                 if (!filp->f_count)
 225                         continue;
 226                 if (filp->f_rdev != dev)
 227                         continue;
 228                 if (filp->f_op != &tty_fops)
 229                         continue;
 230                 filp->f_op = &hung_up_tty_fops;
 231         }
 232         wake_up_interruptible(&tty->secondary.proc_list);
 233         wake_up_interruptible(&tty->read_q.proc_list);
 234         wake_up_interruptible(&tty->write_q.proc_list);
 235         if (tty->session > 0)
 236                 kill_sl(tty->session,SIGHUP,1);
 237         tty->session = 0;
 238         tty->pgrp = -1;
 239         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
 240                 if ((*p) && (*p)->tty == tty->line)
 241                         (*p)->tty = -1;
 242         }
 243 }
 244 
 245 void tty_unhangup(struct file *filp)
     /*  */
 246 {
 247         filp->f_op = &tty_fops;
 248 }
 249 
 250 static inline int hung_up(struct file * filp)
     /*  */
 251 {
 252         return filp->f_op == &hung_up_tty_fops;
 253 }
 254 
 255 /*
 256  * Sometimes we want to wait until a particular VT has been activated. We
 257  * do it in a very simple manner. Everybody waits on a single queue and
 258  * get woken up at once. Those that are satisfied go on with their business,
 259  * while those not ready go back to sleep. Seems overkill to add a wait
 260  * to each vt just for this - usually this does nothing!
 261  */
 262 static struct wait_queue *vt_activate_queue = NULL;
 263 
 264 /*
 265  * Sleeps until a vt is activated, or the task is interrupted. Returns
 266  * 0 if activation, -1 if interrupted.
 267  */
 268 int vt_waitactive(void)
     /*  */
 269 {
 270         interruptible_sleep_on(&vt_activate_queue);
 271         return (current->signal & ~current->blocked) ? -1 : 0;
 272 }
 273 
 274 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 275 
 276 extern int kill_proc(int pid, int sig, int priv);
 277 
 278 /*
 279  * Performs the back end of a vt switch
 280  */
 281 void complete_change_console(unsigned int new_console)
     /*  */
 282 {
 283         unsigned char old_vc_mode;
 284 
 285         if (new_console == fg_console || new_console >= NR_CONSOLES)
 286                 return;
 287 
 288         /*
 289          * If we're switching, we could be going from KD_GRAPHICS to
 290          * KD_TEXT mode or vice versa, which means we need to blank or
 291          * unblank the screen later.
 292          */
 293         old_vc_mode = vt_cons[fg_console].vc_mode;
 294         update_screen(new_console);
 295 
 296         /*
 297          * If this new console is under process control, send it a signal
 298          * telling it that it has acquired. Also check if it has died and
 299          * clean up (similar to logic employed in change_console())
 300          */
 301         if (vt_cons[new_console].vt_mode.mode == VT_PROCESS)
 302         {
 303                 /*
 304                  * Send the signal as privileged - kill_proc() will
 305                  * tell us if the process has gone or something else
 306                  * is awry
 307                  */
 308                 if (kill_proc(vt_cons[new_console].vt_pid,
 309                               vt_cons[new_console].vt_mode.acqsig,
 310                               1) != 0)
 311                 {
 312                 /*
 313                  * The controlling process has died, so we revert back to
 314                  * normal operation. In this case, we'll also change back
 315                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 316                  * but it saves the agony when the X server dies and the screen
 317                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 318                  * this outside of VT_PROCESS but there is no single process
 319                  * to account for and tracking tty count may be undesirable.
 320                  */
 321                         vt_cons[new_console].vc_mode = KD_TEXT;
 322                         clr_vc_kbd_flag(kbd_table + new_console, VC_RAW);
 323                         vt_cons[new_console].vt_mode.mode = VT_AUTO;
 324                         vt_cons[new_console].vt_mode.waitv = 0;
 325                         vt_cons[new_console].vt_mode.relsig = 0;
 326                         vt_cons[new_console].vt_mode.acqsig = 0;
 327                         vt_cons[new_console].vt_mode.frsig = 0;
 328                         vt_cons[new_console].vt_pid = -1;
 329                         vt_cons[new_console].vt_newvt = -1;
 330                 }
 331         }
 332 
 333         /*
 334          * We do this here because the controlling process above may have
 335          * gone, and so there is now a new vc_mode
 336          */
 337         if (old_vc_mode != vt_cons[new_console].vc_mode)
 338         {
 339                 if (vt_cons[new_console].vc_mode == KD_TEXT)
 340                         unblank_screen();
 341                 else
 342                 {
 343                         timer_active &= ~(1<<BLANK_TIMER);
 344                         blank_screen();
 345                 }
 346         }
 347 
 348         /*
 349          * Wake anyone waiting for their VT to activate
 350          */
 351         vt_wake_waitactive();
 352         return;
 353 }
 354 
 355 /*
 356  * Performs the front-end of a vt switch
 357  */
 358 void change_console(unsigned int new_console)
     /*  */
 359 {
 360         if (new_console == fg_console || new_console >= NR_CONSOLES)
 361                 return;
 362 
 363         /*
 364          * If this vt is in process mode, then we need to handshake with
 365          * that process before switching. Essentially, we store where that
 366          * vt wants to switch to and wait for it to tell us when it's done
 367          * (via VT_RELDISP ioctl).
 368          *
 369          * We also check to see if the controlling process still exists.
 370          * If it doesn't, we reset this vt to auto mode and continue.
 371          * This is a cheap way to track process control. The worst thing
 372          * that can happen is: we send a signal to a process, it dies, and
 373          * the switch gets "lost" waiting for a response; hopefully, the
 374          * user will try again, we'll detect the process is gone (unless
 375          * the user waits just the right amount of time :-) and revert the
 376          * vt to auto control.
 377          */
 378         if (vt_cons[fg_console].vt_mode.mode == VT_PROCESS)
 379         {
 380                 /*
 381                  * Send the signal as privileged - kill_proc() will
 382                  * tell us if the process has gone or something else
 383                  * is awry
 384                  */
 385                 if (kill_proc(vt_cons[fg_console].vt_pid,
 386                               vt_cons[fg_console].vt_mode.relsig,
 387                               1) == 0)
 388                 {
 389                         /*
 390                          * It worked. Mark the vt to switch to and
 391                          * return. The process needs to send us a
 392                          * VT_RELDISP ioctl to complete the switch.
 393                          */
 394                         vt_cons[fg_console].vt_newvt = new_console;
 395                         return;
 396                 }
 397 
 398                 /*
 399                  * The controlling process has died, so we revert back to
 400                  * normal operation. In this case, we'll also change back
 401                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 402                  * but it saves the agony when the X server dies and the screen
 403                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 404                  * this outside of VT_PROCESS but there is no single process
 405                  * to account for and tracking tty count may be undesirable.
 406                  */
 407                 vt_cons[fg_console].vc_mode = KD_TEXT;
 408                 clr_vc_kbd_flag(kbd_table + fg_console, VC_RAW);
 409                 vt_cons[fg_console].vt_mode.mode = VT_AUTO;
 410                 vt_cons[fg_console].vt_mode.waitv = 0;
 411                 vt_cons[fg_console].vt_mode.relsig = 0;
 412                 vt_cons[fg_console].vt_mode.acqsig = 0;
 413                 vt_cons[fg_console].vt_mode.frsig = 0;
 414                 vt_cons[fg_console].vt_pid = -1;
 415                 vt_cons[fg_console].vt_newvt = -1;
 416                 /*
 417                  * Fall through to normal (VT_AUTO) handling of the switch...
 418                  */
 419         }
 420 
 421         /*
 422          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 423          */
 424         if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
 425                 return;
 426 
 427         complete_change_console(new_console);
 428 }
 429 
 430 void wait_for_keypress(void)
     /*  */
 431 {
 432         sleep_on(&keypress_wait);
 433 }
 434 
 435 void copy_to_cooked(struct tty_struct * tty)
     /*  */
 436 {
 437         int c;
 438 
 439         if (!tty) {
 440                 printk("copy_to_cooked: called with NULL tty\n");
 441                 return;
 442         }
 443         if (!tty->write) {
 444                 printk("copy_to_cooked: tty %d has null write routine\n",
 445                        tty->line);
 446         }
 447         while (1) {
 448                 /*
 449                  * Check to see how much room we have left in the
 450                  * secondary queue.  Send a throttle command or abort
 451                  * if necessary.
 452                  */
 453                 c = LEFT(&tty->secondary);
 454                 if (tty->throttle && (c < SQ_THRESHOLD_LW)
 455                     && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
 456                         tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
 457                 if (c == 0)
 458                         break;
 459                 c = get_tty_queue(&tty->read_q);
 460                 if (c < 0)
 461                         break;
 462                 if (I_STRP(tty))
 463                         c &= 0x7f;
 464                 if (c==13) {
 465                         if (I_CRNL(tty))
 466                                 c=10;
 467                         else if (I_NOCR(tty))
 468                                 continue;
 469                 } else if (c==10 && I_NLCR(tty))
 470                         c=13;
 471                 if (I_UCLC(tty))
 472                         c=tolower(c);
 473                 if (c == __DISABLED_CHAR)
 474                         tty->lnext = 1;
 475                 if (L_CANON(tty) && !tty->lnext) {
 476                         if (c == KILL_CHAR(tty)) {
 477                                 /* deal with killing the input line */
 478                                 while(!(EMPTY(&tty->secondary) ||
 479                                         (c=LAST(&tty->secondary))==10 ||
 480                                         ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 481                                          (c==EOF_CHAR(tty))))) {
 482                                         if (L_ECHO(tty)) {
 483                                                 if (c<32) {
 484                                                         put_tty_queue(8, &tty->write_q);
 485                                                         put_tty_queue(' ', &tty->write_q);
 486                                                         put_tty_queue(8,&tty->write_q);
 487                                                 }
 488                                                 put_tty_queue(8,&tty->write_q);
 489                                                 put_tty_queue(' ',&tty->write_q);
 490                                                 put_tty_queue(8,&tty->write_q);
 491                                         }
 492                                         DEC(tty->secondary.head);
 493                                 }
 494                                 continue;
 495                         }
 496                         if (c == ERASE_CHAR(tty)) {
 497                                 if (EMPTY(&tty->secondary) ||
 498                                    (c=LAST(&tty->secondary))==10 ||
 499                                    ((EOF_CHAR(tty) != __DISABLED_CHAR) &&
 500                                     (c==EOF_CHAR(tty))))
 501                                         continue;
 502                                 if (L_ECHO(tty)) {
 503                                         if (c<32) {
 504                                                 put_tty_queue(8,&tty->write_q);
 505                                                 put_tty_queue(' ',&tty->write_q);
 506                                                 put_tty_queue(8,&tty->write_q);
 507                                         }
 508                                         put_tty_queue(8,&tty->write_q);
 509                                         put_tty_queue(32,&tty->write_q);
 510                                         put_tty_queue(8,&tty->write_q);
 511                                 }
 512                                 DEC(tty->secondary.head);
 513                                 continue;
 514                         }
 515                         if (c == LNEXT_CHAR(tty)) {
 516                                 tty->lnext = 1;
 517                                 if (L_ECHO(tty)) {
 518                                         put_tty_queue('^',&tty->write_q);
 519                                         put_tty_queue(8,&tty->write_q);
 520                                 }
 521                                 continue;
 522                         }
 523                 }
 524                 if (I_IXON(tty) && !tty->lnext) {
 525                         if (c == STOP_CHAR(tty)) {
 526                                 tty->status_changed = 1;
 527                                 tty->ctrl_status |= TIOCPKT_STOP;
 528                                 tty->stopped=1;
 529                                 continue;
 530                         }
 531                         if (((I_IXANY(tty)) && tty->stopped) ||
 532                             (c == START_CHAR(tty))) {
 533                                 tty->status_changed = 1;
 534                                 tty->ctrl_status |= TIOCPKT_START;
 535                                 tty->stopped=0;
 536                                 continue;
 537                         }
 538                 }
 539                 if (L_ISIG(tty) && !tty->lnext) {
 540                         if (c == INTR_CHAR(tty)) {
 541                                 kill_pg(tty->pgrp, SIGINT, 1);
 542                                 flush_input(tty);
 543                                 continue;
 544                         }
 545                         if (c == QUIT_CHAR(tty)) {
 546                                 kill_pg(tty->pgrp, SIGQUIT, 1);
 547                                 flush_input(tty);
 548                                 continue;
 549                         }
 550                         if (c == SUSPEND_CHAR(tty)) {
 551                                 if (!is_orphaned_pgrp(tty->pgrp))
 552                                         kill_pg(tty->pgrp, SIGTSTP, 1);
 553                                 continue;
 554                         }
 555                 }
 556                 if (c==10 || (EOF_CHAR(tty) != __DISABLED_CHAR &&
 557                     c==EOF_CHAR(tty)))
 558                         tty->secondary.data++;
 559                 if ((c==10) && (L_ECHO(tty) || (L_CANON(tty) && L_ECHONL(tty)))) {
 560                         put_tty_queue(10,&tty->write_q);
 561                         put_tty_queue(13,&tty->write_q);
 562                 } else if (L_ECHO(tty)) {
 563                         if (c<32 && L_ECHOCTL(tty)) {
 564                                 put_tty_queue('^',&tty->write_q);
 565                                 put_tty_queue(c+64, &tty->write_q);
 566                                 if (EOF_CHAR(tty) != __DISABLED_CHAR &&
 567                                     c==EOF_CHAR(tty) && !tty->lnext) {
 568                                         put_tty_queue(8,&tty->write_q);
 569                                         put_tty_queue(8,&tty->write_q);
 570                                 }
 571                         } else
 572                                 put_tty_queue(c, &tty->write_q);
 573                 }
 574                 tty->lnext = 0;
 575                 put_tty_queue(c, &tty->secondary);
 576         }
 577         TTY_WRITE_FLUSH(tty);
 578         if (!EMPTY(&tty->secondary))
 579                 wake_up_interruptible(&tty->secondary.proc_list);
 580         if (tty->write_q.proc_list && LEFT(&tty->write_q) > TTY_BUF_SIZE/2)
 581                 wake_up_interruptible(&tty->write_q.proc_list);
 582         if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
 583             && !clear_bit(TTY_RQ_THROTTLED, &tty->flags))
 584                 tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
 585         if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 586             && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 587                 tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 588 }
 589 
 590 int is_ignored(int sig)
     /*  */
 591 {
 592         return ((current->blocked & (1<<(sig-1))) ||
 593                 (current->sigaction[sig-1].sa_handler == SIG_IGN));
 594 }
 595 
 596 static int available_canon_input(struct tty_struct *);
 597 static void __wait_for_canon_input(struct file * file, struct tty_struct *);
 598 
 599 static void wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 600 {
 601         if (!available_canon_input(tty)) {
 602                 if (current->signal & ~current->blocked)
 603                         return;
 604                 __wait_for_canon_input(file, tty);
 605         }
 606 }
 607 
 608 static int read_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 609 {
 610         struct wait_queue wait = { current, NULL };
 611         int c;
 612         char * b=buf;
 613         int minimum,time;
 614 
 615         if (L_CANON(tty))
 616                 minimum = time = current->timeout = 0;
 617         else {
 618                 time = 10L*tty->termios->c_cc[VTIME];
 619                 minimum = tty->termios->c_cc[VMIN];
 620                 if (minimum)
 621                         current->timeout = 0xffffffff;
 622                 else {
 623                         if (time)
 624                                 current->timeout = time + jiffies;
 625                         else
 626                                 current->timeout = 0;
 627                         time = 0;
 628                         minimum = 1;
 629                 }
 630         }
 631         if (file->f_flags & O_NONBLOCK) {
 632                 time = current->timeout = 0;
 633                 if (L_CANON(tty)) {
 634                         if (!available_canon_input(tty))
 635                                 return -EAGAIN;
 636                 }
 637         } else if (L_CANON(tty)) {
 638                 wait_for_canon_input(file, tty);
 639                 if (current->signal & ~current->blocked)
 640                         return -ERESTARTSYS;
 641         }
 642         if (minimum>nr)
 643                 minimum = nr;
 644 
 645         /* deal with packet mode:  First test for status change */
 646         if (tty->packet && tty->link && tty->link->status_changed) {
 647                 put_fs_byte (tty->link->ctrl_status, b);
 648                 tty->link->status_changed = 0;
 649                 return 1;
 650         }
 651           
 652         /* now bump the buffer up one. */
 653         if (tty->packet) {
 654                 put_fs_byte (0,b++);
 655                 nr--;
 656                 /* this really shouldn't happen, but we need to 
 657                 put it here. */
 658                 if (nr == 0)
 659                         return 1;
 660         }
 661         add_wait_queue(&tty->secondary.proc_list, &wait);
 662         while (nr>0) {
 663                 if (hung_up(file)) {
 664                         file->f_flags &= ~O_NONBLOCK;
 665                         break;  /* force read() to return 0 */
 666                 }
 667                 TTY_READ_FLUSH(tty);
 668                 if (tty->link)
 669                         TTY_WRITE_FLUSH(tty->link);
 670                 while (nr > 0 && ((c = get_tty_queue(&tty->secondary)) >= 0)) {
 671                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 672                              c==EOF_CHAR(tty)) || c==10)
 673                                 tty->secondary.data--;
 674                         if ((EOF_CHAR(tty) != __DISABLED_CHAR &&
 675                              c==EOF_CHAR(tty)) && L_CANON(tty))
 676                                 break;
 677                         put_fs_byte(c,b++);
 678                         nr--;
 679                         if (time)
 680                                 current->timeout = time+jiffies;
 681                         if (c==10 && L_CANON(tty))
 682                                 break;
 683                 };
 684                 wake_up_interruptible(&tty->read_q.proc_list);
 685                 /*
 686                  * If there is enough space in the secondary queue
 687                  * now, let the low-level driver know.
 688                  */
 689                 if (tty->throttle && (LEFT(&tty->secondary) >= SQ_THRESHOLD_HW)
 690                     && !clear_bit(TTY_SQ_THROTTLED, &tty->flags))
 691                         tty->throttle(tty, TTY_THROTTLE_SQ_AVAIL);
 692                 if (b-buf >= minimum || !current->timeout)
 693                         break;
 694                 if (current->signal & ~current->blocked) 
 695                         break;
 696                 if (tty->link && !tty->link->count)
 697                         break;
 698                 TTY_READ_FLUSH(tty);
 699                 if (tty->link)
 700                         TTY_WRITE_FLUSH(tty->link);
 701                 if (!EMPTY(&tty->secondary))
 702                         continue;
 703                 current->state = TASK_INTERRUPTIBLE;
 704                 if (EMPTY(&tty->secondary))
 705                         schedule();
 706                 current->state = TASK_RUNNING;
 707         }
 708         remove_wait_queue(&tty->secondary.proc_list, &wait);
 709         TTY_READ_FLUSH(tty);
 710         if (tty->link && tty->link->write)
 711                 TTY_WRITE_FLUSH(tty->link);
 712         current->timeout = 0;
 713 
 714         /* packet mode sticks in an extra 0.  If that's all we've got,
 715            we should count it a zero bytes. */
 716         if (tty->packet) {
 717                 if ((b-buf) > 1)
 718                         return b-buf;
 719         } else {
 720                 if (b-buf)
 721                         return b-buf;
 722         }
 723 
 724         if (current->signal & ~current->blocked)
 725                 return -ERESTARTSYS;
 726         if (file->f_flags & O_NONBLOCK)
 727                 return -EAGAIN;
 728         return 0;
 729 }
 730 
 731 static void __wait_for_canon_input(struct file * file, struct tty_struct * tty)
     /*  */
 732 {
 733         struct wait_queue wait = { current, NULL };
 734 
 735         add_wait_queue(&tty->secondary.proc_list, &wait);
 736         while (1) {
 737                 current->state = TASK_INTERRUPTIBLE;
 738                 if (available_canon_input(tty))
 739                         break;
 740                 if (current->signal & ~current->blocked)
 741                         break;
 742                 if (hung_up(file))
 743                         break;
 744                 schedule();
 745         }
 746         current->state = TASK_RUNNING;
 747         remove_wait_queue(&tty->secondary.proc_list, &wait);
 748 }
 749 
 750 static int available_canon_input(struct tty_struct * tty)
     /*  */
 751 {
 752         TTY_READ_FLUSH(tty);
 753         if (tty->link)
 754                 if (tty->link->count)
 755                         TTY_WRITE_FLUSH(tty->link);
 756                 else
 757                         return 1;
 758         if (FULL(&tty->read_q))
 759                 return 1;
 760         if (tty->secondary.data)
 761                 return 1;
 762         return 0;
 763 }
 764 
 765 static int write_chan(struct tty_struct * tty, struct file * file, char * buf, int nr)
     /*  */
 766 {
 767         struct wait_queue wait = { current, NULL };
 768         char c, *b=buf;
 769 
 770         if (nr < 0)
 771                 return -EINVAL;
 772         if (!nr)
 773                 return 0;
 774         add_wait_queue(&tty->write_q.proc_list, &wait);
 775         while (nr>0) {
 776                 if (current->signal & ~current->blocked)
 777                         break;
 778                 if (hung_up(file))
 779                         break;
 780                 if (tty->link && !tty->link->count) {
 781                         send_sig(SIGPIPE,current,0);
 782                         break;
 783                 }
 784                 current->state = TASK_INTERRUPTIBLE;
 785                 if (FULL(&tty->write_q)) {
 786                         TTY_WRITE_FLUSH(tty);
 787                         if (FULL(&tty->write_q))
 788                                 schedule();
 789                         current->state = TASK_RUNNING;
 790                         continue;
 791                 }
 792                 current->state = TASK_RUNNING;
 793                 while (nr>0 && !FULL(&tty->write_q)) {
 794                         c=get_fs_byte(b);
 795                         if (O_POST(tty)) {
 796                                 if (c=='\r' && O_CRNL(tty))
 797                                         c='\n';
 798                                 else if (c=='\n' && O_NLRET(tty))
 799                                         c='\r';
 800                                 if (c=='\n' && O_NLCR(tty) &&
 801                                     !set_bit(TTY_CR_PENDING,&tty->flags)) {
 802                                         put_tty_queue(13,&tty->write_q);
 803                                         continue;
 804                                 }
 805                                 if (O_LCUC(tty))
 806                                         c=toupper(c);
 807                         }
 808                         b++; nr--;
 809                         clear_bit(TTY_CR_PENDING,&tty->flags);
 810                         put_tty_queue(c,&tty->write_q);
 811                 }
 812                 if (need_resched)
 813                         schedule();
 814         }
 815         remove_wait_queue(&tty->write_q.proc_list, &wait);
 816         TTY_WRITE_FLUSH(tty);
 817         if (b-buf)
 818                 return b-buf;
 819         if (tty->link && !tty->link->count)
 820                 return -EPIPE;
 821         if (current->signal & ~current->blocked)
 822                 return -ERESTARTSYS;
 823         return 0;
 824 }
 825 
 826 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 827 {
 828         int i, dev;
 829         struct tty_struct * tty;
 830 
 831         dev = file->f_rdev;
 832         if (MAJOR(dev) != 4) {
 833                 printk("tty_read: bad pseudo-major nr #%d\n", MAJOR(dev));
 834                 return -EINVAL;
 835         }
 836         dev = MINOR(dev);
 837         tty = TTY_TABLE(dev);
 838         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 839                 return -EIO;
 840         if ((inode->i_rdev != 0x0400) && /* don't stop on /dev/console */
 841             (tty->pgrp > 0) &&
 842             (current->tty == dev) &&
 843             (tty->pgrp != current->pgrp))
 844                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 845                         return -EIO;
 846                 else {
 847                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 848                         return -ERESTARTSYS;
 849                 }
 850         if (ldiscs[tty->disc].read)
 851                 i = (ldiscs[tty->disc].read)(tty,file,buf,count);
 852         else
 853                 i = -EIO;
 854         if (i > 0)
 855                 inode->i_atime = CURRENT_TIME;
 856         return i;
 857 }
 858 
 859 static int tty_write(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 860 {
 861         int dev, i, is_console;
 862         struct tty_struct * tty;
 863 
 864         dev = file->f_rdev;
 865         is_console = (inode->i_rdev == 0x0400);
 866         if (MAJOR(dev) != 4) {
 867                 printk("tty_write: pseudo-major != 4\n");
 868                 return -EINVAL;
 869         }
 870         dev = MINOR(dev);
 871         if (is_console && redirect)
 872                 tty = redirect;
 873         else
 874                 tty = TTY_TABLE(dev);
 875         if (!tty || !tty->write || (tty->flags & (1 << TTY_IO_ERROR)))
 876                 return -EIO;
 877         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
 878             (current->tty == dev) && (tty->pgrp != current->pgrp)) {
 879                 if (is_orphaned_pgrp(current->pgrp))
 880                         return -EIO;
 881                 if (!is_ignored(SIGTTOU)) {
 882                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
 883                         return -ERESTARTSYS;
 884                 }
 885         }
 886         if (ldiscs[tty->disc].write)
 887                 i = (ldiscs[tty->disc].write)(tty,file,buf,count);
 888         else
 889                 i = -EIO;
 890         if (i > 0)
 891                 inode->i_mtime = CURRENT_TIME;
 892         return i;
 893 }
 894 
 895 /*
 896  * This is so ripe with races that you should *really* not touch this
 897  * unless you know exactly what you are doing. All the changes have to be
 898  * made atomically, or there may be incorrect pointers all over the place.
 899  */
 900 static int init_dev(int dev)
     /*  */
 901 {
 902         struct tty_struct *tty, *o_tty;
 903         struct termios *tp, *o_tp;
 904         int retval;
 905         int o_dev;
 906 
 907         o_dev = PTY_OTHER(dev);
 908         tty = o_tty = NULL;
 909         tp = o_tp = NULL;
 910 repeat:
 911         retval = -EAGAIN;
 912         if (IS_A_PTY_MASTER(dev) && tty_table[dev] && tty_table[dev]->count)
 913                 goto end_init;
 914         retval = -ENOMEM;
 915         if (!tty_table[dev] && !tty) {
 916                 tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
 917                 if (!tty)
 918                         goto end_init;
 919                 initialize_tty_struct(dev, tty);
 920                 goto repeat;
 921         }
 922         if (!tty_termios[dev] && !tp) {
 923                 tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
 924                 if (!tp)
 925                         goto end_init;
 926                 initialize_termios(dev, tp);
 927                 goto repeat;
 928         }
 929         if (IS_A_PTY(dev)) {
 930                 if (!tty_table[o_dev] && !o_tty) {
 931                         o_tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
 932                         if (!o_tty)
 933                                 goto end_init;
 934                         initialize_tty_struct(o_dev, o_tty);
 935                         goto repeat;
 936                 }
 937                 if (!tty_termios[o_dev] && !o_tp) {
 938                         o_tp = (struct termios *) kmalloc(sizeof(struct termios), GFP_KERNEL);
 939                         if (!o_tp)
 940                                 goto end_init;
 941                         initialize_termios(o_dev, o_tp);
 942                         goto repeat;
 943                 }
 944         }
 945         /* Now we have allocated all the structures: update all the pointers.. */
 946         if (!tty_termios[dev]) {
 947                 tty_termios[dev] = tp;
 948                 tp = NULL;
 949         }
 950         if (!tty_table[dev]) {
 951                 tty->termios = tty_termios[dev];
 952                 tty_table[dev] = tty;
 953                 tty = NULL;
 954         }
 955         if (IS_A_PTY(dev)) {
 956                 if (!tty_termios[o_dev]) {
 957                         tty_termios[o_dev] = o_tp;
 958                         o_tp = NULL;
 959                 }
 960                 if (!tty_table[o_dev]) {
 961                         o_tty->termios = tty_termios[o_dev];
 962                         tty_table[o_dev] = o_tty;
 963                         o_tty = NULL;
 964                 }
 965                 tty_table[dev]->link = tty_table[o_dev];
 966                 tty_table[o_dev]->link = tty_table[dev];
 967         }
 968         tty_table[dev]->count++;
 969         if (IS_A_PTY_MASTER(dev))
 970                 tty_table[o_dev]->count++;
 971         retval = 0;
 972 end_init:
 973         if (tty)
 974                 free_page((unsigned long) tty);
 975         if (o_tty)
 976                 free_page((unsigned long) tty);
 977         if (tp)
 978                 kfree_s(tp, sizeof(struct termios));
 979         if (o_tp)
 980                 kfree_s(o_tp, sizeof(struct termios));
 981         return retval;
 982 }
 983 
 984 /*
 985  * Even releasing the tty structures is a tricky business.. We have
 986  * to be very careful that the structures are all released at the
 987  * same time, as interrupts might otherwise get the wrong pointers.
 988  */
 989 static void release_dev(int dev, struct file * filp)
     /*  */
 990 {
 991         struct tty_struct *tty, *o_tty;
 992         struct termios *tp, *o_tp;
 993 
 994         tty = tty_table[dev];
 995         tp = tty_termios[dev];
 996         o_tty = NULL;
 997         o_tp = NULL;
 998         if (!tty) {
 999                 printk("release_dev: tty_table[%d] was NULL\n", dev);
1000                 return;
1001         }
1002         if (!tp) {
1003                 printk("release_dev: tty_termios[%d] was NULL\n", dev);
1004                 return;
1005         }
1006         if (IS_A_PTY(dev)) {
1007                 o_tty = tty_table[PTY_OTHER(dev)];
1008                 o_tp = tty_termios[PTY_OTHER(dev)];
1009                 if (!o_tty) {
1010                         printk("release_dev: pty pair(%d) was NULL\n", dev);
1011                         return;
1012                 }
1013                 if (!o_tp) {
1014                         printk("release_dev: pty pair(%d) termios was NULL\n", dev);
1015                         return;
1016                 }
1017                 if (tty->link != o_tty || o_tty->link != tty) {
1018                         printk("release_dev: bad pty pointers\n");
1019                         return;
1020                 }
1021         }
1022         tty->write_data_cnt = 0; /* Clear out pending trash */
1023         if (tty->close)
1024                 tty->close(tty, filp);
1025         if (IS_A_PTY_MASTER(dev)) {
1026                 if (--tty->link->count < 0) {
1027                         printk("release_dev: bad tty slave count (dev = %d): %d\n",
1028                                dev, tty->count);
1029                         tty->link->count = 0;
1030                 }
1031         }
1032         if (--tty->count < 0) {
1033                 printk("release_dev: bad tty_table[%d]->count: %d\n",
1034                        dev, tty->count);
1035                 tty->count = 0;
1036         }
1037         if (tty->count)
1038                 return;
1039 
1040         if (ldiscs[tty->disc].close != NULL)
1041                 ldiscs[tty->disc].close(tty);
1042 
1043         if (o_tty) {
1044                 if (o_tty->count)
1045                         return;
1046                 else {
1047                         tty_table[PTY_OTHER(dev)] = NULL;
1048                         tty_termios[PTY_OTHER(dev)] = NULL;
1049                 }
1050         }
1051         tty_table[dev] = NULL;
1052         if (IS_A_PTY(dev)) {
1053                 tty_termios[dev] = NULL;
1054                 kfree_s(tp, sizeof(struct termios));
1055         }
1056         if (tty == redirect || o_tty == redirect)
1057                 redirect = NULL;
1058         free_page((unsigned long) tty);
1059         if (o_tty)
1060                 free_page((unsigned long) o_tty);
1061         if (o_tp)
1062                 kfree_s(o_tp, sizeof(struct termios));
1063 }
1064 
1065 /*
1066  * tty_open and tty_release keep up the tty count that contains the
1067  * number of opens done on a tty. We cannot use the inode-count, as
1068  * different inodes might point to the same tty.
1069  *
1070  * Open-counting is needed for pty masters, as well as for keeping
1071  * track of serial lines: DTR is dropped when the last close happens.
1072  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1073  *
1074  * The termios state of a pty is reset on first open so that
1075  * settings don't persist across reuse.
1076  */
1077 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1078 {
1079         struct tty_struct *tty;
1080         int major, minor;
1081         int noctty, retval;
1082 
1083         minor = MINOR(inode->i_rdev);
1084         major = MAJOR(inode->i_rdev);
1085         noctty = filp->f_flags & O_NOCTTY;
1086         if (major == 5) {
1087                 if (!minor) {
1088                         major = 4;
1089                         minor = current->tty;
1090                 }
1091                 noctty = 1;
1092         } else if (major == 4) {
1093                 if (!minor) {
1094                         minor = fg_console + 1;
1095                         noctty = 1;
1096                 }
1097         } else {
1098                 printk("Bad major #%d in tty_open\n", MAJOR(inode->i_rdev));
1099                 return -ENODEV;
1100         }
1101         if (minor <= 0)
1102                 return -ENXIO;
1103         if (IS_A_PTY_MASTER(minor))
1104                 noctty = 1;
1105         filp->f_rdev = (major << 8) | minor;
1106         retval = init_dev(minor);
1107         if (retval)
1108                 return retval;
1109         tty = tty_table[minor];
1110 
1111         /* clean up the packet stuff. */
1112         /*
1113          *  Why is this not done in init_dev?  Right here, if another 
1114          * process opens up a tty in packet mode, all the packet 
1115          * variables get cleared.  Come to think of it, is anything 
1116          * using the packet mode at all???  - Ted, 1/27/93
1117          */
1118         tty->status_changed = 0;
1119         tty->ctrl_status = 0;
1120         tty->packet = 0;
1121 
1122         if (tty->open) {
1123                 retval = tty->open(tty, filp);
1124         } else {
1125                 retval = -ENODEV;
1126         }
1127         if (retval) {
1128                 release_dev(minor, filp);
1129                 return retval;
1130         }
1131         if (!noctty &&
1132             current->leader &&
1133             current->tty<0 &&
1134             tty->session==0) {
1135                 current->tty = minor;
1136                 tty->session = current->session;
1137                 tty->pgrp = current->pgrp;
1138         }
1139         filp->f_rdev = 0x0400 | minor; /* Set it to something normal */
1140         return 0;
1141 }
1142 
1143 /*
1144  * Note that releasing a pty master also releases the child, so
1145  * we have to make the redirection checks after that and on both
1146  * sides of a pty.
1147  */
1148 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1149 {
1150         int dev;
1151 
1152         dev = filp->f_rdev;
1153         if (MAJOR(dev) != 4) {
1154                 printk("tty_release: tty pseudo-major != 4\n");
1155                 return;
1156         }
1157         dev = MINOR(filp->f_rdev);
1158         if (!dev) {
1159                 printk("tty_release: bad f_rdev\n");
1160                 return;
1161         }
1162         release_dev(dev, filp);
1163 }
1164 
1165 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1166 {
1167         int dev;
1168         struct tty_struct * tty;
1169 
1170         dev = filp->f_rdev;
1171         if (MAJOR(dev) != 4) {
1172                 printk("tty_select: tty pseudo-major != 4\n");
1173                 return 0;
1174         }
1175         dev = MINOR(filp->f_rdev);
1176         tty = TTY_TABLE(dev);
1177         if (!tty) {
1178                 printk("tty_select: tty struct for dev %d was NULL\n", dev);
1179                 return 0;
1180         }
1181         switch (sel_type) {
1182                 case SEL_IN:
1183                         if (L_CANON(tty)) {
1184                                 if (available_canon_input(tty))
1185                                         return 1;
1186                         } else if (!EMPTY(&tty->secondary))
1187                                 return 1;
1188                         if (tty->link && !tty->link->count)
1189                                 return 1;
1190 
1191                         /* see if the status byte can be read. */
1192                         if (tty->packet && tty->link &&
1193                             tty->link->status_changed)
1194                                 return 1;
1195 
1196                         select_wait(&tty->secondary.proc_list, wait);
1197                         return 0;
1198                 case SEL_OUT:
1199                         if (!FULL(&tty->write_q))
1200                                 return 1;
1201                         select_wait(&tty->write_q.proc_list, wait);
1202                         return 0;
1203                 case SEL_EX:
1204                         if (tty->link && !tty->link->count)
1205                                 return 1;
1206                         return 0;
1207         }
1208         return 0;
1209 }
1210 
1211 /*
1212  * This implements the "Secure Attention Key" ---  the idea is to
1213  * prevent trojan horses by killing all processes associated with this
1214  * tty when the user hits the "Secure Attention Key".  Required for
1215  * super-paranoid applications --- see the Orange Book for more details.
1216  * 
1217  * This code could be nicer; ideally it should send a HUP, wait a few
1218  * seconds, then send a INT, and then a KILL signal.  But you then
1219  * have to coordinate with the init process, since all processes associated
1220  * with the current tty must be dead before the new getty is allowed
1221  * to spawn.
1222  */
1223 void do_SAK( struct tty_struct *tty)
     /*  */
1224 {
1225         struct task_struct **p;
1226         int line = tty->line;
1227         int session = tty->session;
1228         int             i;
1229         struct file     *filp;
1230         
1231         flush_input(tty);
1232         flush_output(tty);
1233         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1234                 if (!(*p))
1235                         continue;
1236                 if (((*p)->tty == line) ||
1237                     ((session > 0) && ((*p)->session == session)))
1238                         send_sig(SIGKILL, *p, 1);
1239                 else {
1240                         for (i=0; i < NR_FILE; i++) {
1241                                 filp = (*p)->filp[i];
1242                                 if (filp && (filp->f_op == &tty_fops) &&
1243                                     (MINOR(filp->f_rdev) == line)) {
1244                                         send_sig(SIGKILL, *p, 1);
1245                                         break;
1246                                 }
1247                         }
1248                 }
1249         }
1250 }
1251 
1252 /*
1253  * This routine allows a kernel routine to send a large chunk of data
1254  * to a particular tty; if all of the data can be queued up for ouput
1255  * immediately, tty_write_data() will return 0.  If, however, not all
1256  * of the data can be immediately queued for delivery, the number of
1257  * bytes left to be queued up will be returned, and the rest of the
1258  * data will be queued up when there is room.  The callback function
1259  * will be called (with the argument callarg) when the last of the
1260  * data is finally in the queue.
1261  *
1262  * Note that the callback routine will _not_ be called if all of the
1263  * data could be queued immediately.  This is to avoid a problem with
1264  * the kernel stack getting too deep, which might happen if the
1265  * callback routine calls tty_write_data with itself as an argument.
1266  */
1267 int tty_write_data(struct tty_struct *tty, char *bufp, int buflen,
     /*  */
1268                     void (*callback)(void * data), void * callarg)
1269 {
1270         int head, tail, count;
1271         unsigned long flags;
1272         char *p;
1273 
1274 #define VLEFT ((tail-head-1)&(TTY_BUF_SIZE-1))
1275 
1276         __asm__ __volatile__("pushfl ; popl %0 ; cli":"=r" (flags));
1277         if (tty->write_data_cnt) {
1278                 __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1279                 return -EBUSY;
1280         }
1281 
1282         head = tty->write_q.head;
1283         tail = tty->write_q.tail;
1284         count = buflen;
1285         p = bufp;
1286 
1287         while (count && VLEFT > 0) {
1288                 tty->write_q.buf[head++] = *p++;
1289                 head &= TTY_BUF_SIZE-1;
1290         }
1291         tty->write_q.head = head;
1292         if (count) {
1293                 tty->write_data_cnt = count;
1294                 tty->write_data_ptr = p;
1295                 tty->write_data_callback = callback;
1296                 tty->write_data_arg = callarg;
1297         }
1298         __asm__ __volatile__("pushl %0 ; popfl"::"r" (flags));
1299         return count;
1300 }
1301 
1302 /*
1303  * This routine routine is called after an interrupt has drained a
1304  * tty's write queue, so that there is more space for data waiting to
1305  * be sent in tty->write_data_ptr.
1306  *
1307  * tty_check_write[8] is a bitstring which indicates which ttys
1308  * needs to be processed.
1309  */
1310 void tty_bh_routine()
     /*  */
1311 {
1312         int     i, j, line, mask;
1313         int     head, tail, count;
1314         unsigned char * p;
1315         struct tty_struct * tty;
1316 
1317         for (i = 0, line = 0; i < MAX_TTYS / 32; i++) {
1318                 if (!tty_check_write[i]) {
1319                         line += 32;
1320                         continue;
1321                 }
1322                 for (j=0, mask=0; j < 32; j++, line++, mask <<= 1) {
1323                         if (!clear_bit(j, &tty_check_write[i])) {
1324                                 tty = tty_table[line];
1325                                 if (!tty || !tty->write_data_cnt)
1326                                         continue;
1327                                 cli();
1328                                 head = tty->write_q.head;
1329                                 tail = tty->write_q.tail;
1330                                 count = tty->write_data_cnt;
1331                                 p = tty->write_data_ptr;
1332 
1333                                 while (count && VLEFT > 0) {
1334                                         tty->write_q.buf[head++] = *p++;
1335                                         head &= TTY_BUF_SIZE-1;
1336                                 }
1337                                 tty->write_q.head = head;
1338                                 tty->write_data_ptr = p;
1339                                 tty->write_data_cnt = count;
1340                                 sti();
1341                                 if (!count)
1342                                         (tty->write_data_callback)
1343                                                 (tty->write_data_arg);
1344                         }
1345                 }
1346         }
1347         
1348 }
1349 
1350 /*
1351  * This subroutine initializes a tty structure.  We have to set up
1352  * things correctly for each different type of tty.
1353  */
1354 static void initialize_tty_struct(int line, struct tty_struct *tty)
     /*  */
1355 {
1356         memset(tty, 0, sizeof(struct tty_struct));
1357         tty->line = line;
1358         tty->disc = N_TTY;
1359         tty->pgrp = -1;
1360         tty->winsize.ws_row = 24;
1361         tty->winsize.ws_col = 80;
1362         if (IS_A_CONSOLE(line)) {
1363                 tty->open = con_open;
1364                 tty->winsize.ws_row = video_num_lines;
1365                 tty->winsize.ws_col = video_num_columns;
1366         } else if IS_A_SERIAL(line) {
1367                 tty->open = rs_open;
1368         } else if IS_A_PTY(line) {
1369                 tty->open = pty_open;
1370         }
1371 }
1372 
1373 static void initialize_termios(int line, struct termios * tp)
     /*  */
1374 {
1375         memset(tp, 0, sizeof(struct termios));
1376         memcpy(tp->c_cc, INIT_C_CC, NCCS);
1377         if (IS_A_CONSOLE(line)) {
1378                 tp->c_iflag = ICRNL | IXON;
1379                 tp->c_oflag = OPOST | ONLCR;
1380                 tp->c_cflag = B38400 | CS8 | CREAD;
1381                 tp->c_lflag = ISIG | ICANON | ECHO |
1382                         ECHOCTL | ECHOKE;
1383         } else if (IS_A_SERIAL(line)) {
1384                 tp->c_cflag = B2400 | CS8 | CREAD | HUPCL | CLOCAL;
1385         } else if (IS_A_PTY_MASTER(line)) {
1386                 tp->c_cflag = B9600 | CS8 | CREAD;
1387         } else if (IS_A_PTY_SLAVE(line)) {
1388                 tp->c_iflag = ICRNL | IXON;
1389                 tp->c_oflag = OPOST | ONLCR;
1390                 tp->c_cflag = B38400 | CS8 | CREAD;
1391                 tp->c_lflag = ISIG | ICANON | ECHO |
1392                         ECHOCTL | ECHOKE;
1393         }
1394 }
1395 
1396 static struct tty_ldisc tty_ldisc_N_TTY = {
1397         0,                      /* flags */
1398         NULL,                   /* open */
1399         NULL,                   /* close */
1400         read_chan,              /* read */
1401         write_chan,             /* write */
1402         NULL,                   /* ioctl */
1403         copy_to_cooked          /* handler */
1404 };
1405 
1406         
1407 long tty_init(long kmem_start)
     /*  */
1408 {
1409         int i;
1410 
1411         if (sizeof(struct tty_struct) > 4096)
1412                 panic("size of tty structure > 4096!");
1413         if (register_chrdev(4,"tty",&tty_fops))
1414                 panic("unable to get major 4 for tty device");
1415         if (register_chrdev(5,"tty",&tty_fops))
1416                 panic("unable to get major 5 for tty device");
1417         for (i=0 ; i< MAX_TTYS ; i++) {
1418                 tty_table[i] =  0;
1419                 tty_termios[i] = 0;
1420         }
1421         memset(tty_check_write, 0, sizeof(tty_check_write));
1422         bh_base[TTY_BH].routine = tty_bh_routine;
1423 
1424         /* Setup the default TTY line discipline. */
1425         memset(ldiscs, 0, sizeof(ldiscs));
1426         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1427 
1428         kmem_start = kbd_init(kmem_start);
1429         kmem_start = con_init(kmem_start);
1430         kmem_start = rs_init(kmem_start);
1431         return kmem_start;
1432 }
/* */
root/kernel/chr_drv/tty_io.c

DEFINITIONS
