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

DEFINITIONS
