drivers/char/tty

/* */
This source file includes following definitions.
_tty_name
tty_name
tty_paranoia_check
check_tty_count
tty_register_ldisc
tty_set_ldisc
get_tty_driver
tty_check_change
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_hung_up_p
disassociate_ctty
vt_waitactive
reset_vc
complete_change_console
change_console
wait_for_keypress
stop_tty
start_tty
tty_read
tty_write
init_dev
release_dev
tty_open
tty_release
tty_select
fasync_helper
tty_fasync
do_get_ps_info
tty_ioctl
do_SAK
flush_to_ldisc
initialize_tty_struct
tty_default_put_char
tty_register_driver
tty_unregister_driver
console_init
tty_init
   1 /*
   2  *  linux/drivers/char/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 discipline 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  * Rewrote canonical mode and added more termios flags.
  37  *      -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
  38  *
  39  * Reorganized FASYNC support so mouse code can share it.
  40  *      -- ctm@ardi.com, 9Sep95
  41  */
  42 
  43 #include <linux/config.h>
  44 #include <linux/types.h>
  45 #include <linux/major.h>
  46 #include <linux/errno.h>
  47 #include <linux/signal.h>
  48 #include <linux/fcntl.h>
  49 #include <linux/sched.h>
  50 #include <linux/interrupt.h>
  51 #include <linux/tty.h>
  52 #include <linux/tty_flip.h>
  53 #include <linux/timer.h>
  54 #include <linux/ctype.h>
  55 #include <linux/kd.h>
  56 #include <linux/mm.h>
  57 #include <linux/string.h>
  58 #include <linux/malloc.h>
  59 
  60 #include <asm/segment.h>
  61 #include <asm/system.h>
  62 #include <asm/bitops.h>
  63 
  64 #include <linux/scc.h>
  65 
  66 #include "kbd_kern.h"
  67 #include "vt_kern.h"
  68 #include "selection.h"
  69 
  70 #define CONSOLE_DEV MKDEV(TTY_MAJOR,0)
  71 #define TTY_DEV MKDEV(TTYAUX_MAJOR,0)
  72 
  73 #undef TTY_DEBUG_HANGUP
  74 
  75 #define TTY_PARANOIA_CHECK
  76 #define CHECK_TTY_COUNT
  77 
  78 extern void do_blank_screen(int nopowersave);
  79 extern void set_vesa_blanking(const unsigned long arg);
  80 
  81 struct termios tty_std_termios;         /* for the benefit of tty drivers  */
  82 struct tty_driver *tty_drivers = NULL;  /* linked list of tty drivers */
  83 struct tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
  84 
  85 /*
  86  * fg_console is the current virtual console,
  87  * last_console is the last used one
  88  * redirect is the pseudo-tty that console output
  89  * is redirected to if asked by TIOCCONS.
  90  */
  91 int fg_console = 0;
  92 int last_console = 0;
  93 struct tty_struct * redirect = NULL;
  94 struct wait_queue * keypress_wait = NULL;
  95 
  96 static void initialize_tty_struct(struct tty_struct *tty);
  97 
  98 static int tty_read(struct inode *, struct file *, char *, int);
  99 static int tty_write(struct inode *, struct file *, const char *, int);
 100 static int tty_select(struct inode *, struct file *, int, select_table *);
 101 static int tty_open(struct inode *, struct file *);
 102 static void tty_release(struct inode *, struct file *);
 103 static int tty_ioctl(struct inode * inode, struct file * file,
 104                      unsigned int cmd, unsigned long arg);
 105 static int tty_fasync(struct inode * inode, struct file * filp, int on);
 106 
 107 extern void reset_palette(int currcons) ;
 108 extern void set_palette(void) ;
 109 
 110 #ifndef MIN
 111 #define MIN(a,b)        ((a) < (b) ? (a) : (b))
 112 #endif
 113 
 114 /*
 115  * These two routines return the name of tty.  tty_name() should NOT
 116  * be used in interrupt drivers, since it's not re-entrant.  Use
 117  * _tty_name() instead.
 118  */
 119 char *_tty_name(struct tty_struct *tty, char *buf)
     /*  */
 120 {
 121         if (tty)
 122                 sprintf(buf, "%s%d", tty->driver.name,
 123                         MINOR(tty->device) - tty->driver.minor_start +
 124                         tty->driver.name_base);
 125         else
 126                 strcpy(buf, "NULL tty");
 127         return buf;
 128 }
 129 
 130 char *tty_name(struct tty_struct *tty)
     /*  */
 131 {
 132         static char buf[64];
 133 
 134         return(_tty_name(tty, buf));
 135 }
 136 
 137 inline int tty_paranoia_check(struct tty_struct *tty, kdev_t device,
     /*  */
 138                               const char *routine)
 139 {
 140 #ifdef TTY_PARANOIA_CHECK
 141         static const char *badmagic =
 142                 "Warning: bad magic number for tty struct (%s) in %s\n";
 143         static const char *badtty =
 144                 "Warning: null TTY for (%s) in %s\n";
 145 
 146         if (!tty) {
 147                 printk(badtty, kdevname(device), routine);
 148                 return 1;
 149         }
 150         if (tty->magic != TTY_MAGIC) {
 151                 printk(badmagic, kdevname(device), routine);
 152                 return 1;
 153         }
 154 #endif
 155         return 0;
 156 }
 157 
 158 static int check_tty_count(struct tty_struct *tty, const char *routine)
     /*  */
 159 {
 160 #ifdef CHECK_TTY_COUNT
 161         struct file *f;
 162         int i, count = 0;
 163         
 164         for (f = first_file, i=0; i<nr_files; i++, f = f->f_next) {
 165                 if (!f->f_count)
 166                         continue;
 167                 if (f->private_data == tty) {
 168                         count++;
 169                 }
 170         }
 171         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
 172             tty->driver.subtype == PTY_TYPE_SLAVE &&
 173             tty->link && tty->link->count)
 174                 count++;
 175         if (tty->count != count) {
 176                 printk("Warning: dev (%s) tty->count(%d) != #fd's(%d) in %s\n",
 177                        kdevname(tty->device), tty->count, count, routine);
 178                 return count;
 179        }        
 180 #endif
 181         return 0;
 182 }
 183 
 184 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
     /*  */
 185 {
 186         if (disc < N_TTY || disc >= NR_LDISCS)
 187                 return -EINVAL;
 188         
 189         if (new_ldisc) {
 190                 ldiscs[disc] = *new_ldisc;
 191                 ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
 192                 ldiscs[disc].num = disc;
 193         } else
 194                 memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
 195         
 196         return 0;
 197 }
 198 
 199 /* Set the discipline of a tty line. */
 200 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
     /*  */
 201 {
 202         int     retval = 0;
 203         struct  tty_ldisc o_ldisc;
 204 
 205         if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS) ||
 206             !(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED))
 207                 return -EINVAL;
 208 
 209         if (tty->ldisc.num == ldisc)
 210                 return 0;       /* We are already in the desired discipline */
 211         o_ldisc = tty->ldisc;
 212 
 213         tty_wait_until_sent(tty, 0);
 214         
 215         /* Shutdown the current discipline. */
 216         if (tty->ldisc.close)
 217                 (tty->ldisc.close)(tty);
 218 
 219         /* Now set up the new line discipline. */
 220         tty->ldisc = ldiscs[ldisc];
 221         tty->termios->c_line = ldisc;
 222         if (tty->ldisc.open)
 223                 retval = (tty->ldisc.open)(tty);
 224         if (retval < 0) {
 225                 tty->ldisc = o_ldisc;
 226                 tty->termios->c_line = tty->ldisc.num;
 227                 if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
 228                         tty->ldisc = ldiscs[N_TTY];
 229                         tty->termios->c_line = N_TTY;
 230                         if (tty->ldisc.open) {
 231                                 int r = tty->ldisc.open(tty);
 232 
 233                                 if (r < 0)
 234                                         panic("Couldn't open N_TTY ldisc for "
 235                                               "%s --- error %d.",
 236                                               tty_name(tty), r);
 237                         }
 238                 }
 239         }
 240         if (tty->ldisc.num != o_ldisc.num && tty->driver.set_ldisc)
 241                 tty->driver.set_ldisc(tty);
 242         return retval;
 243 }
 244 
 245 /*
 246  * This routine returns a tty driver structure, given a device number
 247  */
 248 struct tty_driver *get_tty_driver(kdev_t device)
     /*  */
 249 {
 250         int     major, minor;
 251         struct tty_driver *p;
 252         
 253         minor = MINOR(device);
 254         major = MAJOR(device);
 255 
 256         for (p = tty_drivers; p; p = p->next) {
 257                 if (p->major != major)
 258                         continue;
 259                 if (minor < p->minor_start)
 260                         continue;
 261                 if (minor >= p->minor_start + p->num)
 262                         continue;
 263                 return p;
 264         }
 265         return NULL;
 266 }
 267 
 268 /*
 269  * If we try to write to, or set the state of, a terminal and we're
 270  * not in the foreground, send a SIGTTOU.  If the signal is blocked or
 271  * ignored, go ahead and perform the operation.  (POSIX 7.2)
 272  */
 273 int tty_check_change(struct tty_struct * tty)
     /*  */
 274 {
 275         if (current->tty != tty)
 276                 return 0;
 277         if (tty->pgrp <= 0) {
 278                 printk("tty_check_change: tty->pgrp <= 0!\n");
 279                 return 0;
 280         }
 281         if (current->pgrp == tty->pgrp)
 282                 return 0;
 283         if (is_ignored(SIGTTOU))
 284                 return 0;
 285         if (is_orphaned_pgrp(current->pgrp))
 286                 return -EIO;
 287         (void) kill_pg(current->pgrp,SIGTTOU,1);
 288         return -ERESTARTSYS;
 289 }
 290 
 291 static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 292 {
 293         return 0;
 294 }
 295 
 296 static int hung_up_tty_write(struct inode * inode, struct file * file, const char * buf, int count)
     /*  */
 297 {
 298         return -EIO;
 299 }
 300 
 301 static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
 302 {
 303         return 1;
 304 }
 305 
 306 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
     /*  */
 307                              unsigned int cmd, unsigned long arg)
 308 {
 309         return -EIO;
 310 }
 311 
 312 static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 313 {
 314         return -ESPIPE;
 315 }
 316 
 317 static struct file_operations tty_fops = {
 318         tty_lseek,
 319         tty_read,
 320         tty_write,
 321         NULL,           /* tty_readdir */
 322         tty_select,
 323         tty_ioctl,
 324         NULL,           /* tty_mmap */
 325         tty_open,
 326         tty_release,
 327         NULL,           /* tty_fsync */
 328         tty_fasync
 329 };
 330 
 331 static struct file_operations hung_up_tty_fops = {
 332         tty_lseek,
 333         hung_up_tty_read,
 334         hung_up_tty_write,
 335         NULL,           /* hung_up_tty_readdir */
 336         hung_up_tty_select,
 337         hung_up_tty_ioctl,
 338         NULL,           /* hung_up_tty_mmap */
 339         NULL,           /* hung_up_tty_open */
 340         tty_release,    /* hung_up_tty_release */
 341         NULL,           /* hung_up_tty_fsync  */
 342         NULL            /* hung_up_tty_fasync */
 343 };
 344 
 345 void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
     /*  */
 346 {
 347         int i;
 348         struct file * filp;
 349         struct task_struct *p;
 350 
 351         if (!tty)
 352                 return;
 353         check_tty_count(tty, "do_tty_hangup");
 354         for (filp = first_file, i=0; i<nr_files; i++, filp = filp->f_next) {
 355                 if (!filp->f_count)
 356                         continue;
 357                 if (filp->private_data != tty)
 358                         continue;
 359                 if (filp->f_inode
 360                     && filp->f_inode->i_rdev == CONSOLE_DEV)
 361                         continue;
 362                 if (filp->f_op != &tty_fops)
 363                         continue;
 364                 tty_fasync(filp->f_inode, filp, 0);
 365                 filp->f_op = fops;
 366         }
 367         
 368         if (tty->ldisc.flush_buffer)
 369                 tty->ldisc.flush_buffer(tty);
 370         if (tty->driver.flush_buffer)
 371                 tty->driver.flush_buffer(tty);
 372         if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
 373             tty->ldisc.write_wakeup)
 374                 (tty->ldisc.write_wakeup)(tty);
 375         wake_up_interruptible(&tty->write_wait);
 376         wake_up_interruptible(&tty->read_wait);
 377 
 378         /*
 379          * Shutdown the current line discipline, and reset it to
 380          * N_TTY.
 381          */
 382         if (tty->ldisc.num != ldiscs[N_TTY].num) {
 383                 if (tty->ldisc.close)
 384                         (tty->ldisc.close)(tty);
 385                 tty->ldisc = ldiscs[N_TTY];
 386                 tty->termios->c_line = N_TTY;
 387                 if (tty->ldisc.open) {
 388                         i = (tty->ldisc.open)(tty);
 389                         if (i < 0)
 390                                 printk("do_tty_hangup: N_TTY open: error %d\n",
 391                                        -i);
 392                 }
 393         }
 394         
 395         for_each_task(p) {
 396                 if ((tty->session > 0) && (p->session == tty->session) &&
 397                     p->leader) {
 398                         send_sig(SIGHUP,p,1);
 399                         send_sig(SIGCONT,p,1);
 400                         if (tty->pgrp > 0)
 401                                 p->tty_old_pgrp = tty->pgrp;
 402                 }
 403                 if (p->tty == tty)
 404                         p->tty = NULL;
 405         }
 406         tty->flags = 0;
 407         tty->session = 0;
 408         tty->pgrp = -1;
 409         tty->ctrl_status = 0;
 410         if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS)
 411                 *tty->termios = tty->driver.init_termios;
 412         if (tty->driver.hangup)
 413                 (tty->driver.hangup)(tty);
 414 }
 415 
 416 void tty_hangup(struct tty_struct * tty)
     /*  */
 417 {
 418 #ifdef TTY_DEBUG_HANGUP
 419         printk("%s hangup...\n", tty_name(tty));
 420 #endif
 421         do_tty_hangup(tty, &hung_up_tty_fops);
 422 }
 423 
 424 void tty_vhangup(struct tty_struct * tty)
     /*  */
 425 {
 426 #ifdef TTY_DEBUG_HANGUP
 427         printk("%s vhangup...\n", tty_name(tty));
 428 #endif
 429         do_tty_hangup(tty, &hung_up_tty_fops);
 430 }
 431 
 432 int tty_hung_up_p(struct file * filp)
     /*  */
 433 {
 434         return (filp->f_op == &hung_up_tty_fops);
 435 }
 436 
 437 /*
 438  * This function is typically called only by the session leader, when
 439  * it wants to disassociate itself from its controlling tty.
 440  *
 441  * It performs the following functions:
 442  *      (1)  Sends a SIGHUP and SIGCONT to the foreground process group
 443  *      (2)  Clears the tty from being controlling the session
 444  *      (3)  Clears the controlling tty for all processes in the
 445  *              session group.
 446  *
 447  * The argument on_exit is set to 1 if called when a process is
 448  * exiting; it is 0 if called by the ioctl TIOCNOTTY.
 449  */
 450 void disassociate_ctty(int on_exit)
     /*  */
 451 {
 452         struct tty_struct *tty = current->tty;
 453         struct task_struct *p;
 454 
 455         if (tty) {
 456                 if (on_exit)
 457                         tty_vhangup(tty);
 458         } else {
 459                 if (current->tty_old_pgrp) {
 460                         kill_pg(current->tty_old_pgrp, SIGHUP, on_exit);
 461                         kill_pg(current->tty_old_pgrp, SIGCONT, on_exit);
 462                 }
 463                 return;
 464         }
 465         if (tty->pgrp > 0) {
 466                 kill_pg(tty->pgrp, SIGHUP, on_exit);
 467                 kill_pg(tty->pgrp, SIGCONT, on_exit);
 468         }
 469 
 470         current->tty_old_pgrp = 0;
 471         tty->session = 0;
 472         tty->pgrp = -1;
 473 
 474         for_each_task(p)
 475                 if (p->session == current->session)
 476                         p->tty = NULL;
 477 }
 478 
 479 /*
 480  * Sometimes we want to wait until a particular VT has been activated. We
 481  * do it in a very simple manner. Everybody waits on a single queue and
 482  * get woken up at once. Those that are satisfied go on with their business,
 483  * while those not ready go back to sleep. Seems overkill to add a wait
 484  * to each vt just for this - usually this does nothing!
 485  */
 486 static struct wait_queue *vt_activate_queue = NULL;
 487 
 488 /*
 489  * Sleeps until a vt is activated, or the task is interrupted. Returns
 490  * 0 if activation, -1 if interrupted.
 491  */
 492 int vt_waitactive(void)
     /*  */
 493 {
 494         interruptible_sleep_on(&vt_activate_queue);
 495         return (current->signal & ~current->blocked) ? -1 : 0;
 496 }
 497 
 498 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 499 
 500 void reset_vc(unsigned int new_console)
     /*  */
 501 {
 502         vt_cons[new_console]->vc_mode = KD_TEXT;
 503         kbd_table[new_console].kbdmode = VC_XLATE;
 504         vt_cons[new_console]->vt_mode.mode = VT_AUTO;
 505         vt_cons[new_console]->vt_mode.waitv = 0;
 506         vt_cons[new_console]->vt_mode.relsig = 0;
 507         vt_cons[new_console]->vt_mode.acqsig = 0;
 508         vt_cons[new_console]->vt_mode.frsig = 0;
 509         vt_cons[new_console]->vt_pid = -1;
 510         vt_cons[new_console]->vt_newvt = -1;
 511         reset_palette (new_console) ;
 512 }
 513 
 514 /*
 515  * Performs the back end of a vt switch
 516  */
 517 void complete_change_console(unsigned int new_console)
     /*  */
 518 {
 519         unsigned char old_vc_mode;
 520 
 521         if (new_console == fg_console)
 522                 return;
 523         if (!vc_cons_allocated(new_console))
 524                 return;
 525         last_console = fg_console;
 526 
 527         /*
 528          * If we're switching, we could be going from KD_GRAPHICS to
 529          * KD_TEXT mode or vice versa, which means we need to blank or
 530          * unblank the screen later.
 531          */
 532         old_vc_mode = vt_cons[fg_console]->vc_mode;
 533         update_screen(new_console);
 534 
 535         /*
 536          * If this new console is under process control, send it a signal
 537          * telling it that it has acquired. Also check if it has died and
 538          * clean up (similar to logic employed in change_console())
 539          */
 540         if (vt_cons[new_console]->vt_mode.mode == VT_PROCESS)
 541         {
 542                 /*
 543                  * Send the signal as privileged - kill_proc() will
 544                  * tell us if the process has gone or something else
 545                  * is awry
 546                  */
 547                 if (kill_proc(vt_cons[new_console]->vt_pid,
 548                               vt_cons[new_console]->vt_mode.acqsig,
 549                               1) != 0)
 550                 {
 551                 /*
 552                  * The controlling process has died, so we revert back to
 553                  * normal operation. In this case, we'll also change back
 554                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 555                  * but it saves the agony when the X server dies and the screen
 556                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 557                  * this outside of VT_PROCESS but there is no single process
 558                  * to account for and tracking tty count may be undesirable.
 559                  */
 560                         reset_vc(new_console);
 561                 }
 562         }
 563 
 564         /*
 565          * We do this here because the controlling process above may have
 566          * gone, and so there is now a new vc_mode
 567          */
 568         if (old_vc_mode != vt_cons[new_console]->vc_mode)
 569         {
 570                 if (vt_cons[new_console]->vc_mode == KD_TEXT)
 571                         do_unblank_screen();
 572                 else
 573                         do_blank_screen(1);
 574         }
 575 
 576         /* Set the colour palette for this VT */
 577         if (vt_cons[new_console]->vc_mode == KD_TEXT)
 578                 set_palette() ;
 579         
 580         /*
 581          * Wake anyone waiting for their VT to activate
 582          */
 583         vt_wake_waitactive();
 584         return;
 585 }
 586 
 587 /*
 588  * Performs the front-end of a vt switch
 589  */
 590 void change_console(unsigned int new_console)
     /*  */
 591 {
 592         if (new_console == fg_console)
 593                 return;
 594         if (!vc_cons_allocated(new_console))
 595                 return;
 596 
 597         /*
 598          * If this vt is in process mode, then we need to handshake with
 599          * that process before switching. Essentially, we store where that
 600          * vt wants to switch to and wait for it to tell us when it's done
 601          * (via VT_RELDISP ioctl).
 602          *
 603          * We also check to see if the controlling process still exists.
 604          * If it doesn't, we reset this vt to auto mode and continue.
 605          * This is a cheap way to track process control. The worst thing
 606          * that can happen is: we send a signal to a process, it dies, and
 607          * the switch gets "lost" waiting for a response; hopefully, the
 608          * user will try again, we'll detect the process is gone (unless
 609          * the user waits just the right amount of time :-) and revert the
 610          * vt to auto control.
 611          */
 612         if (vt_cons[fg_console]->vt_mode.mode == VT_PROCESS)
 613         {
 614                 /*
 615                  * Send the signal as privileged - kill_proc() will
 616                  * tell us if the process has gone or something else
 617                  * is awry
 618                  */
 619                 if (kill_proc(vt_cons[fg_console]->vt_pid,
 620                               vt_cons[fg_console]->vt_mode.relsig,
 621                               1) == 0)
 622                 {
 623                         /*
 624                          * It worked. Mark the vt to switch to and
 625                          * return. The process needs to send us a
 626                          * VT_RELDISP ioctl to complete the switch.
 627                          */
 628                         vt_cons[fg_console]->vt_newvt = new_console;
 629                         return;
 630                 }
 631 
 632                 /*
 633                  * The controlling process has died, so we revert back to
 634                  * normal operation. In this case, we'll also change back
 635                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 636                  * but it saves the agony when the X server dies and the screen
 637                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 638                  * this outside of VT_PROCESS but there is no single process
 639                  * to account for and tracking tty count may be undesirable.
 640                  */
 641                 reset_vc(fg_console);
 642 
 643                 /*
 644                  * Fall through to normal (VT_AUTO) handling of the switch...
 645                  */
 646         }
 647 
 648         /*
 649          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 650          */
 651         if (vt_cons[fg_console]->vc_mode == KD_GRAPHICS)
 652                 return;
 653 
 654         complete_change_console(new_console);
 655 }
 656 
 657 void wait_for_keypress(void)
     /*  */
 658 {
 659         sleep_on(&keypress_wait);
 660 }
 661 
 662 void stop_tty(struct tty_struct *tty)
     /*  */
 663 {
 664         if (tty->stopped)
 665                 return;
 666         tty->stopped = 1;
 667         if (tty->link && tty->link->packet) {
 668                 tty->ctrl_status &= ~TIOCPKT_START;
 669                 tty->ctrl_status |= TIOCPKT_STOP;
 670                 wake_up_interruptible(&tty->link->read_wait);
 671         }
 672         if (tty->driver.stop)
 673                 (tty->driver.stop)(tty);
 674 }
 675 
 676 void start_tty(struct tty_struct *tty)
     /*  */
 677 {
 678         if (!tty->stopped)
 679                 return;
 680         tty->stopped = 0;
 681         if (tty->link && tty->link->packet) {
 682                 tty->ctrl_status &= ~TIOCPKT_STOP;
 683                 tty->ctrl_status |= TIOCPKT_START;
 684                 wake_up_interruptible(&tty->link->read_wait);
 685         }
 686         if (tty->driver.start)
 687                 (tty->driver.start)(tty);
 688         if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
 689             tty->ldisc.write_wakeup)
 690                 (tty->ldisc.write_wakeup)(tty);
 691         wake_up_interruptible(&tty->write_wait);
 692 }
 693 
 694 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 695 {
 696         int i;
 697         struct tty_struct * tty;
 698 
 699         tty = (struct tty_struct *)file->private_data;
 700         if (tty_paranoia_check(tty, inode->i_rdev, "tty_read"))
 701                 return -EIO;
 702         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 703                 return -EIO;
 704 
 705         /* This check not only needs to be done before reading, but also
 706            whenever read_chan() gets woken up after sleeping, so I've
 707            moved it to there.  This should only be done for the N_TTY
 708            line discipline, anyway.  Same goes for write_chan(). -- jlc. */
 709 #if 0
 710         if ((inode->i_rdev != CONSOLE_DEV) && /* don't stop on /dev/console */
 711             (tty->pgrp > 0) &&
 712             (current->tty == tty) &&
 713             (tty->pgrp != current->pgrp))
 714                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 715                         return -EIO;
 716                 else {
 717                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 718                         return -ERESTARTSYS;
 719                 }
 720 #endif
 721         if (tty->ldisc.read)
 722                 /* XXX casts are for what kernel-wide prototypes should be. */
 723                 i = (tty->ldisc.read)(tty,file,(unsigned char *)buf,(unsigned int)count);
 724         else
 725                 i = -EIO;
 726         if (i > 0)
 727                 inode->i_atime = CURRENT_TIME;
 728         return i;
 729 }
 730 
 731 static int tty_write(struct inode * inode, struct file * file, const char * buf, int count)
     /*  */
 732 {
 733         int i, is_console;
 734         struct tty_struct * tty;
 735 
 736         is_console = (inode->i_rdev == CONSOLE_DEV);
 737 
 738         if (is_console && redirect)
 739                 tty = redirect;
 740         else
 741                 tty = (struct tty_struct *)file->private_data;
 742         if (tty_paranoia_check(tty, inode->i_rdev, "tty_write"))
 743                 return -EIO;
 744         if (!tty || !tty->driver.write || (tty->flags & (1 << TTY_IO_ERROR)))
 745                 return -EIO;
 746 #if 0
 747         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
 748             (current->tty == tty) && (tty->pgrp != current->pgrp)) {
 749                 if (is_orphaned_pgrp(current->pgrp))
 750                         return -EIO;
 751                 if (!is_ignored(SIGTTOU)) {
 752                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
 753                         return -ERESTARTSYS;
 754                 }
 755         }
 756 #endif
 757         if (tty->ldisc.write)
 758                 /* XXX casts are for what kernel-wide prototypes should be. */
 759                 i = (tty->ldisc.write)(tty,file,(const unsigned char *)buf,(unsigned int)count);
 760         else
 761                 i = -EIO;
 762         if (i > 0)
 763                 inode->i_mtime = CURRENT_TIME;
 764         return i;
 765 }
 766 
 767 /*
 768  * This is so ripe with races that you should *really* not touch this
 769  * unless you know exactly what you are doing. All the changes have to be
 770  * made atomically, or there may be incorrect pointers all over the place.
 771  */
 772 static int init_dev(kdev_t device, struct tty_struct **ret_tty)
     /*  */
 773 {
 774         struct tty_struct *tty, **tty_loc, *o_tty, **o_tty_loc;
 775         struct termios *tp, **tp_loc, *o_tp, **o_tp_loc;
 776         struct termios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
 777         struct tty_driver *driver;      
 778         int retval;
 779         int idx;
 780 
 781         driver = get_tty_driver(device);
 782         if (!driver)
 783                 return -ENODEV;
 784 
 785         idx = MINOR(device) - driver->minor_start;
 786         tty = o_tty = NULL;
 787         tp = o_tp = NULL;
 788         ltp = o_ltp = NULL;
 789         o_tty_loc = NULL;
 790         o_tp_loc = o_ltp_loc = NULL;
 791 
 792         tty_loc = &driver->table[idx];
 793         tp_loc = &driver->termios[idx];
 794         ltp_loc = &driver->termios_locked[idx];
 795 
 796 repeat:
 797         retval = -EAGAIN;
 798         if (driver->type == TTY_DRIVER_TYPE_PTY &&
 799             driver->subtype == PTY_TYPE_MASTER &&
 800             *tty_loc && (*tty_loc)->count)
 801                 goto end_init;
 802         retval = -ENOMEM;
 803         if (!*tty_loc && !tty) {
 804                 if (!(tty = (struct tty_struct*) get_free_page(GFP_KERNEL)))
 805                         goto end_init;
 806                 initialize_tty_struct(tty);
 807                 tty->device = device;
 808                 tty->driver = *driver;
 809                 goto repeat;
 810         }
 811         if (!*tp_loc && !tp) {
 812                 tp = (struct termios *) kmalloc(sizeof(struct termios),
 813                                                 GFP_KERNEL);
 814                 if (!tp)
 815                         goto end_init;
 816                 *tp = driver->init_termios;
 817                 goto repeat;
 818         }
 819         if (!*ltp_loc && !ltp) {
 820                 ltp = (struct termios *) kmalloc(sizeof(struct termios),
 821                                                  GFP_KERNEL);
 822                 if (!ltp)
 823                         goto end_init;
 824                 memset(ltp, 0, sizeof(struct termios));
 825                 goto repeat;
 826         }
 827         if (driver->type == TTY_DRIVER_TYPE_PTY) {
 828                 o_tty_loc = &driver->other->table[idx];
 829                 o_tp_loc = &driver->other->termios[idx];
 830                 o_ltp_loc = &driver->other->termios_locked[idx];
 831 
 832                 if (!*o_tty_loc && !o_tty) {
 833                         kdev_t  o_device;
 834                         
 835                         o_tty = (struct tty_struct *)
 836                                 get_free_page(GFP_KERNEL);
 837                         if (!o_tty)
 838                                 goto end_init;
 839                         o_device = MKDEV(driver->other->major,
 840                                          driver->other->minor_start + idx);
 841                         initialize_tty_struct(o_tty);
 842                         o_tty->device = o_device;
 843                         o_tty->driver = *driver->other;
 844                         goto repeat;
 845                 }
 846                 if (!*o_tp_loc && !o_tp) {
 847                         o_tp = (struct termios *)
 848                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
 849                         if (!o_tp)
 850                                 goto end_init;
 851                         *o_tp = driver->other->init_termios;
 852                         goto repeat;
 853                 }
 854                 if (!*o_ltp_loc && !o_ltp) {
 855                         o_ltp = (struct termios *)
 856                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
 857                         if (!o_ltp)
 858                                 goto end_init;
 859                         memset(o_ltp, 0, sizeof(struct termios));
 860                         goto repeat;
 861                 }
 862                 
 863         }
 864         /* Now we have allocated all the structures: update all the pointers.. */
 865         if (!*tp_loc) {
 866                 *tp_loc = tp;
 867                 tp = NULL;
 868         }
 869         if (!*ltp_loc) {
 870                 *ltp_loc = ltp;
 871                 ltp = NULL;
 872         }
 873         if (!*tty_loc) {
 874                 tty->termios = *tp_loc;
 875                 tty->termios_locked = *ltp_loc;
 876                 *tty_loc = tty;
 877                 (*driver->refcount)++;
 878                 (*tty_loc)->count++;
 879                 if (tty->ldisc.open) {
 880                         retval = (tty->ldisc.open)(tty);
 881                         if (retval < 0) {
 882                                 (*tty_loc)->count--;
 883                                 tty = NULL;
 884                                 goto end_init;
 885                         }
 886                 }
 887                 tty = NULL;
 888         } else {
 889                 if ((*tty_loc)->flags & (1 << TTY_CLOSING)) {
 890                         printk("Attempt to open closing tty %s.\n",
 891                                tty_name(*tty_loc));
 892                         printk("Ack!!!!  This should never happen!!\n");
 893                         return -EINVAL;
 894                 }
 895                 (*tty_loc)->count++;
 896         }
 897         if (driver->type == TTY_DRIVER_TYPE_PTY) {
 898                 if (!*o_tp_loc) {
 899                         *o_tp_loc = o_tp;
 900                         o_tp = NULL;
 901                 }
 902                 if (!*o_ltp_loc) {
 903                         *o_ltp_loc = o_ltp;
 904                         o_ltp = NULL;
 905                 }
 906                 if (!*o_tty_loc) {
 907                         o_tty->termios = *o_tp_loc;
 908                         o_tty->termios_locked = *o_ltp_loc;
 909                         *o_tty_loc = o_tty;
 910                         (*driver->other->refcount)++;
 911                         if (o_tty->ldisc.open) {
 912                                 retval = (o_tty->ldisc.open)(o_tty);
 913                                 if (retval < 0) {
 914                                         (*tty_loc)->count--;
 915                                         o_tty = NULL;
 916                                         goto end_init;
 917                                 }
 918                         }
 919                         o_tty = NULL;
 920                 }
 921                 (*tty_loc)->link = *o_tty_loc;
 922                 (*o_tty_loc)->link = *tty_loc;
 923                 if (driver->subtype == PTY_TYPE_MASTER)
 924                         (*o_tty_loc)->count++;
 925         }
 926         (*tty_loc)->driver = *driver;
 927         *ret_tty = *tty_loc;
 928         retval = 0;
 929 end_init:
 930         if (tty)
 931                 free_page((unsigned long) tty);
 932         if (o_tty)
 933                 free_page((unsigned long) o_tty);
 934         if (tp)
 935                 kfree_s(tp, sizeof(struct termios));
 936         if (o_tp)
 937                 kfree_s(o_tp, sizeof(struct termios));
 938         if (ltp)
 939                 kfree_s(ltp, sizeof(struct termios));
 940         if (o_ltp)
 941                 kfree_s(o_ltp, sizeof(struct termios));
 942         return retval;
 943 }
 944 
 945 /*
 946  * Even releasing the tty structures is a tricky business.. We have
 947  * to be very careful that the structures are all released at the
 948  * same time, as interrupts might otherwise get the wrong pointers.
 949  */
 950 static void release_dev(struct file * filp)
     /*  */
 951 {
 952         struct tty_struct *tty, *o_tty;
 953         struct termios *tp, *o_tp, *ltp, *o_ltp;
 954         struct task_struct **p;
 955         int     idx;
 956         
 957         tty = (struct tty_struct *)filp->private_data;
 958         if (tty_paranoia_check(tty, filp->f_inode->i_rdev, "release_dev"))
 959                 return;
 960 
 961         check_tty_count(tty, "release_dev");
 962 
 963         tty_fasync(filp->f_inode, filp, 0);
 964 
 965         tp = tty->termios;
 966         ltp = tty->termios_locked;
 967 
 968         idx = MINOR(tty->device) - tty->driver.minor_start;
 969 #ifdef TTY_PARANOIA_CHECK
 970         if (idx < 0 || idx >= tty->driver.num) {
 971                 printk("release_dev: bad idx when trying to free (%s)\n",
 972                        kdevname(tty->device));
 973                 return;
 974         }
 975         if (tty != tty->driver.table[idx]) {
 976                 printk("release_dev: driver.table[%d] not tty for (%s)\n",
 977                        idx, kdevname(tty->device));
 978                 return;
 979         }
 980         if (tp != tty->driver.termios[idx]) {
 981                 printk("release_dev: driver.termios[%d] not termios for ("
 982                        "%s)\n",
 983                        idx, kdevname(tty->device));
 984                 return;
 985         }
 986         if (ltp != tty->driver.termios_locked[idx]) {
 987                 printk("release_dev: driver.termios_locked[%d] not termios_locked for ("
 988                        "%s)\n",
 989                        idx, kdevname(tty->device));
 990                 return;
 991         }
 992 #endif
 993 
 994 #ifdef TTY_DEBUG_HANGUP
 995         printk("release_dev of %s (tty count=%d)...", tty_name(tty),
 996                tty->count);
 997 #endif
 998 
 999         o_tty = tty->link;
1000         o_tp = (o_tty) ? o_tty->termios : NULL;
1001         o_ltp = (o_tty) ? o_tty->termios_locked : NULL;
1002 
1003 #ifdef TTY_PARANOIA_CHECK
1004         if (tty->driver.other) {
1005                 if (o_tty != tty->driver.other->table[idx]) {
1006                         printk("release_dev: other->table[%d] not o_tty for ("
1007                                "%s)\n",
1008                                idx, kdevname(tty->device));
1009                         return;
1010                 }
1011                 if (o_tp != tty->driver.other->termios[idx]) {
1012                         printk("release_dev: other->termios[%d] not o_termios for ("
1013                                "%s)\n",
1014                                idx, kdevname(tty->device));
1015                         return;
1016                 }
1017                 if (o_ltp != tty->driver.other->termios_locked[idx]) {
1018                         printk("release_dev: other->termios_locked[%d] not o_termios_locked for ("
1019                                "%s)\n",
1020                                idx, kdevname(tty->device));
1021                         return;
1022                 }
1023 
1024                 if (o_tty->link != tty) {
1025                         printk("release_dev: bad pty pointers\n");
1026                         return;
1027                 }
1028         }
1029 #endif
1030         
1031         if (tty->driver.close)
1032                 tty->driver.close(tty, filp);
1033         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1034             tty->driver.subtype == PTY_TYPE_MASTER) {
1035                 if (--tty->link->count < 0) {
1036                         printk("release_dev: bad pty slave count (%d) for %s\n",
1037                                tty->count, tty_name(tty));
1038                         tty->link->count = 0;
1039                 }
1040         }
1041         if (--tty->count < 0) {
1042                 printk("release_dev: bad tty->count (%d) for %s\n",
1043                        tty->count, tty_name(tty));
1044                 tty->count = 0;
1045         }
1046         if (tty->count)
1047                 return;
1048 
1049         /*
1050          * We're committed; at this point, we must not block!
1051          */
1052         if (o_tty) {
1053                 if (o_tty->count)
1054                         return;
1055                 tty->driver.other->table[idx] = NULL;
1056                 tty->driver.other->termios[idx] = NULL;
1057                 kfree_s(o_tp, sizeof(struct termios));
1058         }
1059         
1060 #ifdef TTY_DEBUG_HANGUP
1061         printk("freeing tty structure...");
1062 #endif
1063         tty->flags |= (1 << TTY_CLOSING);
1064 
1065         /*
1066          * Make sure there aren't any processes that still think this
1067          * tty is their controlling tty.
1068          */
1069         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1070                 if (*p == 0)
1071                         continue;
1072                 if ((*p)->tty == tty)
1073                         (*p)->tty = NULL;
1074                 if (o_tty && (*p)->tty == o_tty)
1075                         (*p)->tty = NULL;
1076         }
1077 
1078         /*
1079          * Shutdown the current line discipline, and reset it to
1080          * N_TTY.
1081          */
1082         if (tty->ldisc.close)
1083                 (tty->ldisc.close)(tty);
1084         tty->ldisc = ldiscs[N_TTY];
1085         tty->termios->c_line = N_TTY;
1086         if (o_tty) {
1087                 if (o_tty->ldisc.close)
1088                         (o_tty->ldisc.close)(o_tty);
1089                 o_tty->ldisc = ldiscs[N_TTY];
1090         }
1091         
1092         tty->driver.table[idx] = NULL;
1093         if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS) {
1094                 tty->driver.termios[idx] = NULL;
1095                 kfree_s(tp, sizeof(struct termios));
1096         }
1097         if (tty == redirect || o_tty == redirect)
1098                 redirect = NULL;
1099         /*
1100          * Make sure that the tty's task queue isn't activated.  If it
1101          * is, take it out of the linked list.
1102          */
1103         cli();
1104         if (tty->flip.tqueue.sync) {
1105                 struct tq_struct *tq, *prev;
1106 
1107                 for (tq=tq_timer, prev=0; tq; prev=tq, tq=tq->next) {
1108                         if (tq == &tty->flip.tqueue) {
1109                                 if (prev)
1110                                         prev->next = tq->next;
1111                                 else
1112                                         tq_timer = tq->next;
1113                                 break;
1114                         }
1115                 }
1116         }
1117         sti();
1118         tty->magic = 0;
1119         (*tty->driver.refcount)--;
1120         free_page((unsigned long) tty);
1121         filp->private_data = 0;
1122         if (o_tty) {
1123                 o_tty->magic = 0;
1124                 (*o_tty->driver.refcount)--;
1125                 free_page((unsigned long) o_tty);
1126         }
1127 }
1128 
1129 /*
1130  * tty_open and tty_release keep up the tty count that contains the
1131  * number of opens done on a tty. We cannot use the inode-count, as
1132  * different inodes might point to the same tty.
1133  *
1134  * Open-counting is needed for pty masters, as well as for keeping
1135  * track of serial lines: DTR is dropped when the last close happens.
1136  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1137  *
1138  * The termios state of a pty is reset on first open so that
1139  * settings don't persist across reuse.
1140  */
1141 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1142 {
1143         struct tty_struct *tty;
1144         int minor;
1145         int noctty, retval;
1146         kdev_t device;
1147 
1148 retry_open:
1149         noctty = filp->f_flags & O_NOCTTY;
1150         device = inode->i_rdev;
1151         if (device == TTY_DEV) {
1152                 if (!current->tty)
1153                         return -ENXIO;
1154                 device = current->tty->device;
1155                 /* noctty = 1; */
1156         }
1157         if (device == CONSOLE_DEV) {
1158                 device = MKDEV(TTY_MAJOR, fg_console+1);
1159                 noctty = 1;
1160         }
1161         minor = MINOR(device);
1162         
1163         retval = init_dev(device, &tty);
1164         if (retval)
1165                 return retval;
1166         filp->private_data = tty;
1167         check_tty_count(tty, "tty_open");
1168         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1169             tty->driver.subtype == PTY_TYPE_MASTER)
1170                 noctty = 1;
1171 #ifdef TTY_DEBUG_HANGUP
1172         printk("opening %s...", tty_name(tty));
1173 #endif
1174         if (tty->driver.open)
1175                 retval = tty->driver.open(tty, filp);
1176         else
1177                 retval = -ENODEV;
1178 
1179         if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !suser())
1180                 retval = -EBUSY;
1181 
1182         if (retval) {
1183 #ifdef TTY_DEBUG_HANGUP
1184                 printk("error %d in opening %s...", retval, tty_name(tty));
1185 #endif
1186 
1187                 release_dev(filp);
1188                 if (retval != -ERESTARTSYS)
1189                         return retval;
1190                 if (current->signal & ~current->blocked)
1191                         return retval;
1192                 schedule();
1193                 /*
1194                  * Need to reset f_op in case a hangup happened.
1195                  */
1196                 filp->f_op = &tty_fops;
1197                 goto retry_open;
1198         }
1199         if (!noctty &&
1200             current->leader &&
1201             !current->tty &&
1202             tty->session == 0) {
1203                 current->tty = tty;
1204                 current->tty_old_pgrp = 0;
1205                 tty->session = current->session;
1206                 tty->pgrp = current->pgrp;
1207         }
1208         return 0;
1209 }
1210 
1211 /*
1212  * Note that releasing a pty master also releases the child, so
1213  * we have to make the redirection checks after that and on both
1214  * sides of a pty.
1215  */
1216 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1217 {
1218         release_dev(filp);
1219 }
1220 
1221 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1222 {
1223         struct tty_struct * tty;
1224 
1225         tty = (struct tty_struct *)filp->private_data;
1226         if (tty_paranoia_check(tty, inode->i_rdev, "tty_select"))
1227                 return 0;
1228 
1229         if (tty->ldisc.select)
1230                 return (tty->ldisc.select)(tty, inode, filp, sel_type, wait);
1231         return 0;
1232 }
1233 
1234 /*
1235  * fasync_helper() is used by some character device drivers (mainly mice)
1236  * to set up the fasync queue. It returns negative on error, 0 if it did
1237  * no changes and positive if it added/deleted the entry.
1238  */
1239 int fasync_helper(struct inode * inode, struct file * filp, int on, struct fasync_struct **fapp)
     /*  */
1240 {
1241         struct fasync_struct *fa, **fp;
1242         unsigned long flags;
1243 
1244         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
1245                 if (fa->fa_file == filp)
1246                         break;
1247         }
1248 
1249         if (on) {
1250                 if (fa)
1251                         return 0;
1252                 fa = (struct fasync_struct *)kmalloc(sizeof(struct fasync_struct), GFP_KERNEL);
1253                 if (!fa)
1254                         return -ENOMEM;
1255                 fa->magic = FASYNC_MAGIC;
1256                 fa->fa_file = filp;
1257                 save_flags(flags);
1258                 cli();
1259                 fa->fa_next = *fapp;
1260                 *fapp = fa;
1261                 restore_flags(flags);
1262                 return 1;
1263         }
1264         if (!fa)
1265                 return 0;
1266         save_flags(flags);
1267         cli();
1268         *fp = fa->fa_next;
1269         restore_flags(flags);
1270         kfree(fa);
1271         return 1;
1272 }
1273 
1274 static int tty_fasync(struct inode * inode, struct file * filp, int on)
     /*  */
1275 {
1276         struct tty_struct * tty;
1277         int retval;
1278 
1279         tty = (struct tty_struct *)filp->private_data;
1280         if (tty_paranoia_check(tty, inode->i_rdev, "tty_fasync"))
1281                 return 0;
1282         
1283         retval = fasync_helper(inode, filp, on, &tty->fasync);
1284         if (retval <= 0)
1285                 return retval;
1286 
1287         if (on) {
1288                 if (!tty->read_wait)
1289                         tty->minimum_to_wake = 1;
1290                 if (filp->f_owner == 0) {
1291                         if (tty->pgrp)
1292                                 filp->f_owner = -tty->pgrp;
1293                         else
1294                                 filp->f_owner = current->pid;
1295                 }
1296         } else {
1297                 if (!tty->fasync && !tty->read_wait)
1298                         tty->minimum_to_wake = N_TTY_BUF_SIZE;
1299         }
1300         return 0;
1301 }
1302 
1303 #if 0
1304 /*
1305  * XXX does anyone use this anymore?!?
1306  */
1307 static int do_get_ps_info(unsigned long arg)
     /*  */
1308 {
1309         struct tstruct {
1310                 int flag;
1311                 int present[NR_TASKS];
1312                 struct task_struct tasks[NR_TASKS];
1313         };
1314         struct tstruct *ts = (struct tstruct *)arg;
1315         struct task_struct **p;
1316         char *c, *d;
1317         int i, n = 0;
1318         
1319         i = verify_area(VERIFY_WRITE, (void *)arg, sizeof(struct tstruct));
1320         if (i)
1321                 return i;
1322         for (p = &FIRST_TASK ; p <= &LAST_TASK ; p++, n++)
1323                 if (*p)
1324                 {
1325                         c = (char *)(*p);
1326                         d = (char *)(ts->tasks+n);
1327                         for (i=0 ; i<sizeof(struct task_struct) ; i++)
1328                                 put_user(*c++, d++);
1329                         put_user(1, ts->present+n);
1330                 }
1331                 else    
1332                         put_user(0, ts->present+n);
1333         return(0);                      
1334 }
1335 #endif
1336 
1337 static int tty_ioctl(struct inode * inode, struct file * file,
     /*  */
1338                      unsigned int cmd, unsigned long arg)
1339 {
1340         int     retval;
1341         struct tty_struct * tty;
1342         struct tty_struct * real_tty;
1343         struct winsize tmp_ws;
1344         pid_t pgrp;
1345         unsigned char   ch;
1346         char    mbz = 0;
1347         
1348         tty = (struct tty_struct *)file->private_data;
1349         if (tty_paranoia_check(tty, inode->i_rdev, "tty_ioctl"))
1350                 return -EINVAL;
1351 
1352         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1353             tty->driver.subtype == PTY_TYPE_MASTER)
1354                 real_tty = tty->link;
1355         else
1356                 real_tty = tty;
1357 
1358         switch (cmd) {
1359                 case TIOCSTI:
1360                         if ((current->tty != tty) && !suser())
1361                                 return -EPERM;
1362                         retval = verify_area(VERIFY_READ, (void *) arg, 1);
1363                         if (retval)
1364                                 return retval;
1365                         ch = get_user((char *) arg);
1366                         tty->ldisc.receive_buf(tty, &ch, &mbz, 1);
1367                         return 0;
1368                 case TIOCGWINSZ:
1369                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1370                                              sizeof (struct winsize));
1371                         if (retval)
1372                                 return retval;
1373                         memcpy_tofs((struct winsize *) arg, &tty->winsize,
1374                                     sizeof (struct winsize));
1375                         return 0;
1376                 case TIOCSWINSZ:
1377                         retval = verify_area(VERIFY_READ, (void *) arg,
1378                                              sizeof (struct winsize));
1379                         if (retval)
1380                                 return retval;                  
1381                         memcpy_fromfs(&tmp_ws, (struct winsize *) arg,
1382                                       sizeof (struct winsize));
1383                         if (memcmp(&tmp_ws, &tty->winsize,
1384                                    sizeof(struct winsize))) {
1385                                 if (tty->pgrp > 0)
1386                                         kill_pg(tty->pgrp, SIGWINCH, 1);
1387                                 if ((real_tty->pgrp != tty->pgrp) &&
1388                                     (real_tty->pgrp > 0))
1389                                         kill_pg(real_tty->pgrp, SIGWINCH, 1);
1390                         }
1391                         tty->winsize = tmp_ws;
1392                         real_tty->winsize = tmp_ws;
1393                         return 0;
1394                 case TIOCCONS:
1395                         if (tty->driver.type == TTY_DRIVER_TYPE_CONSOLE) {
1396                                 if (!suser())
1397                                         return -EPERM;
1398                                 redirect = NULL;
1399                                 return 0;
1400                         }
1401                         if (redirect)
1402                                 return -EBUSY;
1403                         redirect = real_tty;
1404                         return 0;
1405                 case FIONBIO:
1406                         retval = verify_area(VERIFY_READ, (void *) arg, sizeof(int));
1407                         if (retval)
1408                                 return retval;
1409                         arg = get_user((unsigned int *) arg);
1410                         if (arg)
1411                                 file->f_flags |= O_NONBLOCK;
1412                         else
1413                                 file->f_flags &= ~O_NONBLOCK;
1414                         return 0;
1415                 case TIOCEXCL:
1416                         set_bit(TTY_EXCLUSIVE, &tty->flags);
1417                         return 0;
1418                 case TIOCNXCL:
1419                         clear_bit(TTY_EXCLUSIVE, &tty->flags);
1420                         return 0;
1421                 case TIOCNOTTY:
1422                         if (current->tty != tty)
1423                                 return -ENOTTY;
1424                         if (current->leader)
1425                                 disassociate_ctty(0);
1426                         current->tty = NULL;
1427                         return 0;
1428                 case TIOCSCTTY:
1429                         if (current->leader &&
1430                             (current->session == tty->session))
1431                                 return 0;
1432                         /*
1433                          * The process must be a session leader and
1434                          * not have a controlling tty already.
1435                          */
1436                         if (!current->leader || current->tty)
1437                                 return -EPERM;
1438                         if (tty->session > 0) {
1439                                 /*
1440                                  * This tty is already the controlling
1441                                  * tty for another session group!
1442                                  */
1443                                 if ((arg == 1) && suser()) {
1444                                         /*
1445                                          * Steal it away
1446                                          */
1447                                         struct task_struct *p;
1448 
1449                                         for_each_task(p)
1450                                                 if (p->tty == tty)
1451                                                         p->tty = NULL;
1452                                 } else
1453                                         return -EPERM;
1454                         }
1455                         current->tty = tty;
1456                         current->tty_old_pgrp = 0;
1457                         tty->session = current->session;
1458                         tty->pgrp = current->pgrp;
1459                         return 0;
1460                 case TIOCGPGRP:
1461                         /*
1462                          * (tty == real_tty) is a cheap way of
1463                          * testing if the tty is NOT a master pty.
1464                          */
1465                         if (tty == real_tty && current->tty != real_tty)
1466                                 return -ENOTTY;
1467                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1468                                              sizeof (pid_t));
1469                         if (retval)
1470                                 return retval;
1471                         put_user(real_tty->pgrp, (pid_t *) arg);
1472                         return 0;
1473                 case TIOCSPGRP:
1474                         retval = tty_check_change(real_tty);
1475                         if (retval)
1476                                 return retval;
1477                         if (!current->tty ||
1478                             (current->tty != real_tty) ||
1479                             (real_tty->session != current->session))
1480                                 return -ENOTTY;
1481                         pgrp = get_user((pid_t *) arg);
1482                         if (pgrp < 0)
1483                                 return -EINVAL;
1484                         if (session_of_pgrp(pgrp) != current->session)
1485                                 return -EPERM;
1486                         real_tty->pgrp = pgrp;
1487                         return 0;
1488                 case TIOCGETD:
1489                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1490                                              sizeof (int));
1491                         if (retval)
1492                                 return retval;
1493                         put_user(tty->ldisc.num, (int *) arg);
1494                         return 0;
1495                 case TIOCSETD:
1496                         retval = tty_check_change(tty);
1497                         if (retval)
1498                                 return retval;
1499                         arg = get_user((int *) arg);
1500                         return tty_set_ldisc(tty, arg);
1501                 case TIOCLINUX:
1502                         if (tty->driver.type != TTY_DRIVER_TYPE_CONSOLE)
1503                                 return -EINVAL;
1504                         if (current->tty != tty && !suser())
1505                                 return -EPERM;
1506                         retval = verify_area(VERIFY_READ, (void *) arg, 1);
1507                         if (retval)
1508                                 return retval;
1509                         switch (retval = get_user((char *)arg))
1510                         {
1511                                 case 0:
1512                                 case 8:
1513                                 case 9:
1514                                         printk("TIOCLINUX (0/8/9) ioctl is gone - use /dev/vcs\n");
1515                                         return -EINVAL;
1516 #if 0
1517                                 case 1:
1518                                         printk("Deprecated TIOCLINUX (1) ioctl\n");
1519                                         return do_get_ps_info(arg);
1520 #endif
1521                                 case 2:
1522                                         return set_selection(arg, tty);
1523                                 case 3:
1524                                         return paste_selection(tty);
1525                                 case 4:
1526                                         do_unblank_screen();
1527                                         return 0;
1528                                 case 5:
1529                                         return sel_loadlut(arg);
1530                                 case 6:
1531                         /*
1532                          * Make it possible to react to Shift+Mousebutton.
1533                          * Note that 'shift_state' is an undocumented
1534                          * kernel-internal variable; programs not closely
1535                          * related to the kernel should not use this.
1536                          */
1537                                         put_user(shift_state,(char *) arg);
1538                                         return 0;
1539                                 case 7:
1540                                         put_user(mouse_reporting(),(char *) arg);
1541                                         return 0;
1542                                 case 10:
1543                                         set_vesa_blanking(arg);
1544                                         return 0;
1545                                 default: 
1546                                         return -EINVAL;
1547                         }
1548 
1549                 case TIOCTTYGSTRUCT:
1550                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1551                                                 sizeof(struct tty_struct));
1552                         if (retval)
1553                                 return retval;
1554                         memcpy_tofs((struct tty_struct *) arg,
1555                                     tty, sizeof(struct tty_struct));
1556                         return 0;
1557                 default:
1558                         if (tty->driver.ioctl) {
1559                                 retval = (tty->driver.ioctl)(tty, file,
1560                                                              cmd, arg);
1561                                 if (retval != -ENOIOCTLCMD)
1562                                         return retval;
1563                         }
1564                         if (tty->ldisc.ioctl) {
1565                                 retval = (tty->ldisc.ioctl)(tty, file,
1566                                                             cmd, arg);
1567                                 if (retval != -ENOIOCTLCMD)
1568                                         return retval;
1569                         }
1570                         return -EINVAL;
1571                 }
1572 }
1573 
1574 
1575 /*
1576  * This implements the "Secure Attention Key" ---  the idea is to
1577  * prevent trojan horses by killing all processes associated with this
1578  * tty when the user hits the "Secure Attention Key".  Required for
1579  * super-paranoid applications --- see the Orange Book for more details.
1580  * 
1581  * This code could be nicer; ideally it should send a HUP, wait a few
1582  * seconds, then send a INT, and then a KILL signal.  But you then
1583  * have to coordinate with the init process, since all processes associated
1584  * with the current tty must be dead before the new getty is allowed
1585  * to spawn.
1586  */
1587 void do_SAK( struct tty_struct *tty)
     /*  */
1588 {
1589 #ifdef TTY_SOFT_SAK
1590         tty_hangup(tty);
1591 #else
1592         struct task_struct **p;
1593         int session;
1594         int             i;
1595         struct file     *filp;
1596         
1597         if (!tty)
1598                 return;
1599         session  = tty->session;
1600         if (tty->ldisc.flush_buffer)
1601                 tty->ldisc.flush_buffer(tty);
1602         if (tty->driver.flush_buffer)
1603                 tty->driver.flush_buffer(tty);
1604         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1605                 if (!(*p))
1606                         continue;
1607                 if (((*p)->tty == tty) ||
1608                     ((session > 0) && ((*p)->session == session)))
1609                         send_sig(SIGKILL, *p, 1);
1610                 else {
1611                         for (i=0; i < NR_OPEN; i++) {
1612                                 filp = (*p)->files->fd[i];
1613                                 if (filp && (filp->f_op == &tty_fops) &&
1614                                     (filp->private_data == tty)) {
1615                                         send_sig(SIGKILL, *p, 1);
1616                                         break;
1617                                 }
1618                         }
1619                 }
1620         }
1621 #endif
1622 }
1623 
1624 /*
1625  * This routine is called out of the software interrupt to flush data
1626  * from the flip buffer to the line discipline.
1627  */
1628 static void flush_to_ldisc(void *private_)
     /*  */
1629 {
1630         struct tty_struct *tty = (struct tty_struct *) private_;
1631         unsigned char   *cp;
1632         char            *fp;
1633         int             count;
1634 
1635         if (tty->flip.buf_num) {
1636                 cp = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
1637                 fp = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
1638                 tty->flip.buf_num = 0;
1639 
1640                 cli();
1641                 tty->flip.char_buf_ptr = tty->flip.char_buf;
1642                 tty->flip.flag_buf_ptr = tty->flip.flag_buf;
1643         } else {
1644                 cp = tty->flip.char_buf;
1645                 fp = tty->flip.flag_buf;
1646                 tty->flip.buf_num = 1;
1647 
1648                 cli();
1649                 tty->flip.char_buf_ptr = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
1650                 tty->flip.flag_buf_ptr = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
1651         }
1652         count = tty->flip.count;
1653         tty->flip.count = 0;
1654         sti();
1655         
1656 #if 0
1657         if (count > tty->max_flip_cnt)
1658                 tty->max_flip_cnt = count;
1659 #endif
1660         tty->ldisc.receive_buf(tty, cp, fp, count);
1661 }
1662 
1663 /*
1664  * This subroutine initializes a tty structure.
1665  */
1666 static void initialize_tty_struct(struct tty_struct *tty)
     /*  */
1667 {
1668         memset(tty, 0, sizeof(struct tty_struct));
1669         tty->magic = TTY_MAGIC;
1670         tty->ldisc = ldiscs[N_TTY];
1671         tty->pgrp = -1;
1672         tty->flip.char_buf_ptr = tty->flip.char_buf;
1673         tty->flip.flag_buf_ptr = tty->flip.flag_buf;
1674         tty->flip.tqueue.routine = flush_to_ldisc;
1675         tty->flip.tqueue.data = tty;
1676 }
1677 
1678 /*
1679  * The default put_char routine if the driver did not define one.
1680  */
1681 void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
     /*  */
1682 {
1683         tty->driver.write(tty, 0, &ch, 1);
1684 }
1685 
1686 /*
1687  * Called by a tty driver to register itself.
1688  */
1689 int tty_register_driver(struct tty_driver *driver)
     /*  */
1690 {
1691         int error;
1692 
1693         if (driver->flags & TTY_DRIVER_INSTALLED)
1694                 return 0;
1695 
1696         error = register_chrdev(driver->major, driver->name, &tty_fops);
1697         if (error < 0)
1698                 return error;
1699         else if(driver->major == 0)
1700                 driver->major = error;
1701 
1702         if (!driver->put_char)
1703                 driver->put_char = tty_default_put_char;
1704         
1705         driver->prev = 0;
1706         driver->next = tty_drivers;
1707         if (tty_drivers) tty_drivers->prev = driver;
1708         tty_drivers = driver;
1709         return error;
1710 }
1711 
1712 /*
1713  * Called by a tty driver to unregister itself.
1714  */
1715 int tty_unregister_driver(struct tty_driver *driver)
     /*  */
1716 {
1717         int     retval;
1718         struct tty_driver *p;
1719         int     found = 0;
1720         const char *othername = NULL;
1721         
1722         if (*driver->refcount)
1723                 return -EBUSY;
1724 
1725         for (p = tty_drivers; p; p = p->next) {
1726                 if (p == driver)
1727                         found++;
1728                 else if (p->major == driver->major)
1729                         othername = p->name;
1730         }
1731 
1732         if (othername == NULL) {
1733                 retval = unregister_chrdev(driver->major, driver->name);
1734                 if (retval)
1735                         return retval;
1736         } else
1737                 register_chrdev(driver->major, othername, &tty_fops);
1738 
1739         if (driver->prev)
1740                 driver->prev->next = driver->next;
1741         else
1742                 tty_drivers = driver->next;
1743         
1744         if (driver->next)
1745                 driver->next->prev = driver->prev;
1746 
1747         return 0;
1748 }
1749 
1750 
1751 /*
1752  * Initialize the console device. This is called *early*, so
1753  * we can't necessarily depend on lots of kernel help here.
1754  * Just do some early initializations, and do the complex setup
1755  * later.
1756  */
1757 long console_init(long kmem_start, long kmem_end)
     /*  */
1758 {
1759         /* Setup the default TTY line discipline. */
1760         memset(ldiscs, 0, sizeof(ldiscs));
1761         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1762 
1763         /*
1764          * Set up the standard termios.  Individual tty drivers may 
1765          * deviate from this; this is used as a template.
1766          */
1767         memset(&tty_std_termios, 0, sizeof(struct termios));
1768         memcpy(tty_std_termios.c_cc, INIT_C_CC, NCCS);
1769         tty_std_termios.c_iflag = ICRNL | IXON;
1770         tty_std_termios.c_oflag = OPOST | ONLCR;
1771         tty_std_termios.c_cflag = B38400 | CS8 | CREAD;
1772         tty_std_termios.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
1773                 ECHOCTL | ECHOKE | IEXTEN;
1774 
1775         /*
1776          * set up the console device so that later boot sequences can 
1777          * inform about problems etc..
1778          */
1779         return con_init(kmem_start);
1780 }
1781 
1782 /*
1783  * Ok, now we can initialize the rest of the tty devices and can count
1784  * on memory allocations, interrupts etc..
1785  */
1786 int tty_init(void)
     /*  */
1787 {
1788         if (sizeof(struct tty_struct) > PAGE_SIZE)
1789                 panic("size of tty structure > PAGE_SIZE!");
1790         kbd_init();
1791         rs_init();
1792 #ifdef CONFIG_SCC
1793         scc_init();
1794 #endif
1795 #ifdef CONFIG_CYCLADES
1796         cy_init();
1797 #endif
1798 #ifdef CONFIG_STALLION
1799         stl_init();
1800 #endif
1801 #ifdef CONFIG_ISTALLION
1802         stli_init();
1803 #endif
1804         pty_init();
1805         vcs_init();
1806         if (register_chrdev(TTY_MAJOR,"tty",&tty_fops))
1807                 panic("unable to get major %d for tty device", TTY_MAJOR);
1808         if (register_chrdev(TTYAUX_MAJOR,"cua",&tty_fops))
1809                 panic("unable to get major %d for tty device", TTYAUX_MAJOR);
1810 
1811         return 0;
1812 }
/* */
root/drivers/char/tty_io.c

DEFINITIONS
