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

DEFINITIONS
