drivers/char/tty

/* */
This source file includes following definitions.
_tty_name
tty_name
tty_paranoia_check
check_tty_count
tty_register_ldisc
tty_set_ldisc
get_tty_driver
tty_check_change
hung_up_tty_read
hung_up_tty_write
hung_up_tty_select
hung_up_tty_ioctl
tty_lseek
do_tty_hangup
tty_hangup
tty_vhangup
tty_hung_up_p
disassociate_ctty
vt_waitactive
reset_vc
complete_change_console
change_console
wait_for_keypress
stop_tty
start_tty
tty_read
tty_write
init_dev
release_dev
tty_open
tty_release
tty_select
fasync_helper
tty_fasync
do_get_ps_info
tty_ioctl
do_SAK
flush_to_ldisc
initialize_tty_struct
tty_default_put_char
tty_register_driver
tty_unregister_driver
console_init
tty_init
   1 /*
   2  *  linux/drivers/char/tty_io.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
   9  * or rs-channels. It also implements echoing, cooked mode etc.
  10  *
  11  * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
  12  *
  13  * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
  14  * tty_struct and tty_queue structures.  Previously there was a array
  15  * of 256 tty_struct's which was statically allocated, and the
  16  * tty_queue structures were allocated at boot time.  Both are now
  17  * dynamically allocated only when the tty is open.
  18  *
  19  * Also restructured routines so that there is more of a separation
  20  * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
  21  * the low-level tty routines (serial.c, pty.c, console.c).  This
  22  * makes for cleaner and more compact code.  -TYT, 9/17/92 
  23  *
  24  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
  25  * which can be dynamically activated and de-activated by the line
  26  * discipline handling modules (like SLIP).
  27  *
  28  * NOTE: pay no attention to the line discipline code (yet); its
  29  * interface is still subject to change in this version...
  30  * -- TYT, 1/31/92
  31  *
  32  * Added functionality to the OPOST tty handling.  No delays, but all
  33  * other bits should be there.
  34  *      -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
  35  *
  36  * Rewrote canonical mode and added more termios flags.
  37  *      -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
  38  *
  39  * Reorganized FASYNC support so mouse code can share it.
  40  *      -- ctm@ardi.com, 9Sep95
  41  *
  42  * New TIOCLINUX variants added.
  43  *      -- mj@k332.feld.cvut.cz, 19-Nov-95
  44  * 
  45  * Restrict vt switching via ioctl()
  46  *      -- grif@cs.ucr.edu, 5-Dec-95
  47  */
  48 
  49 #include <linux/config.h>
  50 #include <linux/types.h>
  51 #include <linux/major.h>
  52 #include <linux/errno.h>
  53 #include <linux/signal.h>
  54 #include <linux/fcntl.h>
  55 #include <linux/sched.h>
  56 #include <linux/interrupt.h>
  57 #include <linux/tty.h>
  58 #include <linux/tty_flip.h>
  59 #include <linux/timer.h>
  60 #include <linux/ctype.h>
  61 #include <linux/kd.h>
  62 #include <linux/mm.h>
  63 #include <linux/string.h>
  64 #include <linux/malloc.h>
  65 
  66 #include <asm/segment.h>
  67 #include <asm/system.h>
  68 #include <asm/bitops.h>
  69 
  70 #include <linux/scc.h>
  71 
  72 #include "kbd_kern.h"
  73 #include "vt_kern.h"
  74 #include "selection.h"
  75 
  76 #define CONSOLE_DEV MKDEV(TTY_MAJOR,0)
  77 #define TTY_DEV MKDEV(TTYAUX_MAJOR,0)
  78 
  79 #undef TTY_DEBUG_HANGUP
  80 
  81 #define TTY_PARANOIA_CHECK
  82 #define CHECK_TTY_COUNT
  83 
  84 extern void do_blank_screen(int nopowersave);
  85 extern void set_vesa_blanking(const unsigned long arg);
  86 
  87 struct termios tty_std_termios;         /* for the benefit of tty drivers  */
  88 struct tty_driver *tty_drivers = NULL;  /* linked list of tty drivers */
  89 struct tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
  90 
  91 /*
  92  * fg_console is the current virtual console,
  93  * last_console is the last used one,
  94  * kmsg_redirect is the console for kernel messages,
  95  * redirect is the pseudo-tty that console output
  96  * is redirected to if asked by TIOCCONS.
  97  */
  98 int fg_console = 0;
  99 int last_console = 0;
 100 int kmsg_redirect = 0;
 101 struct tty_struct * redirect = NULL;
 102 struct wait_queue * keypress_wait = NULL;
 103 char vt_dont_switch = 0;
 104 
 105 static void initialize_tty_struct(struct tty_struct *tty);
 106 
 107 static int tty_read(struct inode *, struct file *, char *, int);
 108 static int tty_write(struct inode *, struct file *, const char *, int);
 109 static int tty_select(struct inode *, struct file *, int, select_table *);
 110 static int tty_open(struct inode *, struct file *);
 111 static void tty_release(struct inode *, struct file *);
 112 static int tty_ioctl(struct inode * inode, struct file * file,
 113                      unsigned int cmd, unsigned long arg);
 114 static int tty_fasync(struct inode * inode, struct file * filp, int on);
 115 
 116 extern void reset_palette(int currcons) ;
 117 extern void set_palette(void) ;
 118 
 119 #ifndef MIN
 120 #define MIN(a,b)        ((a) < (b) ? (a) : (b))
 121 #endif
 122 
 123 /*
 124  * These two routines return the name of tty.  tty_name() should NOT
 125  * be used in interrupt drivers, since it's not re-entrant.  Use
 126  * _tty_name() instead.
 127  */
 128 char *_tty_name(struct tty_struct *tty, char *buf)
     /*  */
 129 {
 130         if (tty)
 131                 sprintf(buf, "%s%d", tty->driver.name,
 132                         MINOR(tty->device) - tty->driver.minor_start +
 133                         tty->driver.name_base);
 134         else
 135                 strcpy(buf, "NULL tty");
 136         return buf;
 137 }
 138 
 139 char *tty_name(struct tty_struct *tty)
     /*  */
 140 {
 141         static char buf[64];
 142 
 143         return(_tty_name(tty, buf));
 144 }
 145 
 146 inline int tty_paranoia_check(struct tty_struct *tty, kdev_t device,
     /*  */
 147                               const char *routine)
 148 {
 149 #ifdef TTY_PARANOIA_CHECK
 150         static const char *badmagic =
 151                 "Warning: bad magic number for tty struct (%s) in %s\n";
 152         static const char *badtty =
 153                 "Warning: null TTY for (%s) in %s\n";
 154 
 155         if (!tty) {
 156                 printk(badtty, kdevname(device), routine);
 157                 return 1;
 158         }
 159         if (tty->magic != TTY_MAGIC) {
 160                 printk(badmagic, kdevname(device), routine);
 161                 return 1;
 162         }
 163 #endif
 164         return 0;
 165 }
 166 
 167 static int check_tty_count(struct tty_struct *tty, const char *routine)
     /*  */
 168 {
 169 #ifdef CHECK_TTY_COUNT
 170         struct file *f;
 171         int i, count = 0;
 172         
 173         for (f = first_file, i=0; i<nr_files; i++, f = f->f_next) {
 174                 if (!f->f_count)
 175                         continue;
 176                 if (f->private_data == tty) {
 177                         count++;
 178                 }
 179         }
 180         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
 181             tty->driver.subtype == PTY_TYPE_SLAVE &&
 182             tty->link && tty->link->count)
 183                 count++;
 184         if (tty->count != count) {
 185                 printk("Warning: dev (%s) tty->count(%d) != #fd's(%d) in %s\n",
 186                        kdevname(tty->device), tty->count, count, routine);
 187                 return count;
 188        }        
 189 #endif
 190         return 0;
 191 }
 192 
 193 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
     /*  */
 194 {
 195         if (disc < N_TTY || disc >= NR_LDISCS)
 196                 return -EINVAL;
 197         
 198         if (new_ldisc) {
 199                 ldiscs[disc] = *new_ldisc;
 200                 ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
 201                 ldiscs[disc].num = disc;
 202         } else
 203                 memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
 204         
 205         return 0;
 206 }
 207 
 208 /* Set the discipline of a tty line. */
 209 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
     /*  */
 210 {
 211         int     retval = 0;
 212         struct  tty_ldisc o_ldisc;
 213 
 214         if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS) ||
 215             !(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED))
 216                 return -EINVAL;
 217 
 218         if (tty->ldisc.num == ldisc)
 219                 return 0;       /* We are already in the desired discipline */
 220         o_ldisc = tty->ldisc;
 221 
 222         tty_wait_until_sent(tty, 0);
 223         
 224         /* Shutdown the current discipline. */
 225         if (tty->ldisc.close)
 226                 (tty->ldisc.close)(tty);
 227 
 228         /* Now set up the new line discipline. */
 229         tty->ldisc = ldiscs[ldisc];
 230         tty->termios->c_line = ldisc;
 231         if (tty->ldisc.open)
 232                 retval = (tty->ldisc.open)(tty);
 233         if (retval < 0) {
 234                 tty->ldisc = o_ldisc;
 235                 tty->termios->c_line = tty->ldisc.num;
 236                 if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
 237                         tty->ldisc = ldiscs[N_TTY];
 238                         tty->termios->c_line = N_TTY;
 239                         if (tty->ldisc.open) {
 240                                 int r = tty->ldisc.open(tty);
 241 
 242                                 if (r < 0)
 243                                         panic("Couldn't open N_TTY ldisc for "
 244                                               "%s --- error %d.",
 245                                               tty_name(tty), r);
 246                         }
 247                 }
 248         }
 249         if (tty->ldisc.num != o_ldisc.num && tty->driver.set_ldisc)
 250                 tty->driver.set_ldisc(tty);
 251         return retval;
 252 }
 253 
 254 /*
 255  * This routine returns a tty driver structure, given a device number
 256  */
 257 struct tty_driver *get_tty_driver(kdev_t device)
     /*  */
 258 {
 259         int     major, minor;
 260         struct tty_driver *p;
 261         
 262         minor = MINOR(device);
 263         major = MAJOR(device);
 264 
 265         for (p = tty_drivers; p; p = p->next) {
 266                 if (p->major != major)
 267                         continue;
 268                 if (minor < p->minor_start)
 269                         continue;
 270                 if (minor >= p->minor_start + p->num)
 271                         continue;
 272                 return p;
 273         }
 274         return NULL;
 275 }
 276 
 277 /*
 278  * If we try to write to, or set the state of, a terminal and we're
 279  * not in the foreground, send a SIGTTOU.  If the signal is blocked or
 280  * ignored, go ahead and perform the operation.  (POSIX 7.2)
 281  */
 282 int tty_check_change(struct tty_struct * tty)
     /*  */
 283 {
 284         if (current->tty != tty)
 285                 return 0;
 286         if (tty->pgrp <= 0) {
 287                 printk("tty_check_change: tty->pgrp <= 0!\n");
 288                 return 0;
 289         }
 290         if (current->pgrp == tty->pgrp)
 291                 return 0;
 292         if (is_ignored(SIGTTOU))
 293                 return 0;
 294         if (is_orphaned_pgrp(current->pgrp))
 295                 return -EIO;
 296         (void) kill_pg(current->pgrp,SIGTTOU,1);
 297         return -ERESTARTSYS;
 298 }
 299 
 300 static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 301 {
 302         return 0;
 303 }
 304 
 305 static int hung_up_tty_write(struct inode * inode, struct file * file, const char * buf, int count)
     /*  */
 306 {
 307         return -EIO;
 308 }
 309 
 310 static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
 311 {
 312         return 1;
 313 }
 314 
 315 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
     /*  */
 316                              unsigned int cmd, unsigned long arg)
 317 {
 318         return -EIO;
 319 }
 320 
 321 static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 322 {
 323         return -ESPIPE;
 324 }
 325 
 326 static struct file_operations tty_fops = {
 327         tty_lseek,
 328         tty_read,
 329         tty_write,
 330         NULL,           /* tty_readdir */
 331         tty_select,
 332         tty_ioctl,
 333         NULL,           /* tty_mmap */
 334         tty_open,
 335         tty_release,
 336         NULL,           /* tty_fsync */
 337         tty_fasync
 338 };
 339 
 340 static struct file_operations hung_up_tty_fops = {
 341         tty_lseek,
 342         hung_up_tty_read,
 343         hung_up_tty_write,
 344         NULL,           /* hung_up_tty_readdir */
 345         hung_up_tty_select,
 346         hung_up_tty_ioctl,
 347         NULL,           /* hung_up_tty_mmap */
 348         NULL,           /* hung_up_tty_open */
 349         tty_release,    /* hung_up_tty_release */
 350         NULL,           /* hung_up_tty_fsync  */
 351         NULL            /* hung_up_tty_fasync */
 352 };
 353 
 354 void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
     /*  */
 355 {
 356         int i;
 357         struct file * filp;
 358         struct task_struct *p;
 359 
 360         if (!tty)
 361                 return;
 362         check_tty_count(tty, "do_tty_hangup");
 363         for (filp = first_file, i=0; i<nr_files; i++, filp = filp->f_next) {
 364                 if (!filp->f_count)
 365                         continue;
 366                 if (filp->private_data != tty)
 367                         continue;
 368                 if (filp->f_inode
 369                     && filp->f_inode->i_rdev == CONSOLE_DEV)
 370                         continue;
 371                 if (filp->f_op != &tty_fops)
 372                         continue;
 373                 tty_fasync(filp->f_inode, filp, 0);
 374                 filp->f_op = fops;
 375         }
 376         
 377         if (tty->ldisc.flush_buffer)
 378                 tty->ldisc.flush_buffer(tty);
 379         if (tty->driver.flush_buffer)
 380                 tty->driver.flush_buffer(tty);
 381         if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
 382             tty->ldisc.write_wakeup)
 383                 (tty->ldisc.write_wakeup)(tty);
 384         wake_up_interruptible(&tty->write_wait);
 385         wake_up_interruptible(&tty->read_wait);
 386 
 387         /*
 388          * Shutdown the current line discipline, and reset it to
 389          * N_TTY.
 390          */
 391         if (tty->ldisc.num != ldiscs[N_TTY].num) {
 392                 if (tty->ldisc.close)
 393                         (tty->ldisc.close)(tty);
 394                 tty->ldisc = ldiscs[N_TTY];
 395                 tty->termios->c_line = N_TTY;
 396                 if (tty->ldisc.open) {
 397                         i = (tty->ldisc.open)(tty);
 398                         if (i < 0)
 399                                 printk("do_tty_hangup: N_TTY open: error %d\n",
 400                                        -i);
 401                 }
 402         }
 403         
 404         for_each_task(p) {
 405                 if ((tty->session > 0) && (p->session == tty->session) &&
 406                     p->leader) {
 407                         send_sig(SIGHUP,p,1);
 408                         send_sig(SIGCONT,p,1);
 409                         if (tty->pgrp > 0)
 410                                 p->tty_old_pgrp = tty->pgrp;
 411                 }
 412                 if (p->tty == tty)
 413                         p->tty = NULL;
 414         }
 415         tty->flags = 0;
 416         tty->session = 0;
 417         tty->pgrp = -1;
 418         tty->ctrl_status = 0;
 419         if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS)
 420                 *tty->termios = tty->driver.init_termios;
 421         if (tty->driver.hangup)
 422                 (tty->driver.hangup)(tty);
 423 }
 424 
 425 void tty_hangup(struct tty_struct * tty)
     /*  */
 426 {
 427 #ifdef TTY_DEBUG_HANGUP
 428         printk("%s hangup...\n", tty_name(tty));
 429 #endif
 430         do_tty_hangup(tty, &hung_up_tty_fops);
 431 }
 432 
 433 void tty_vhangup(struct tty_struct * tty)
     /*  */
 434 {
 435 #ifdef TTY_DEBUG_HANGUP
 436         printk("%s vhangup...\n", tty_name(tty));
 437 #endif
 438         do_tty_hangup(tty, &hung_up_tty_fops);
 439 }
 440 
 441 int tty_hung_up_p(struct file * filp)
     /*  */
 442 {
 443         return (filp->f_op == &hung_up_tty_fops);
 444 }
 445 
 446 /*
 447  * This function is typically called only by the session leader, when
 448  * it wants to disassociate itself from its controlling tty.
 449  *
 450  * It performs the following functions:
 451  *      (1)  Sends a SIGHUP and SIGCONT to the foreground process group
 452  *      (2)  Clears the tty from being controlling the session
 453  *      (3)  Clears the controlling tty for all processes in the
 454  *              session group.
 455  *
 456  * The argument on_exit is set to 1 if called when a process is
 457  * exiting; it is 0 if called by the ioctl TIOCNOTTY.
 458  */
 459 void disassociate_ctty(int on_exit)
     /*  */
 460 {
 461         struct tty_struct *tty = current->tty;
 462         struct task_struct *p;
 463 
 464         if (tty) {
 465                 if (on_exit)
 466                         tty_vhangup(tty);
 467         } else {
 468                 if (current->tty_old_pgrp) {
 469                         kill_pg(current->tty_old_pgrp, SIGHUP, on_exit);
 470                         kill_pg(current->tty_old_pgrp, SIGCONT, on_exit);
 471                 }
 472                 return;
 473         }
 474         if (tty->pgrp > 0) {
 475                 kill_pg(tty->pgrp, SIGHUP, on_exit);
 476                 kill_pg(tty->pgrp, SIGCONT, on_exit);
 477         }
 478 
 479         current->tty_old_pgrp = 0;
 480         tty->session = 0;
 481         tty->pgrp = -1;
 482 
 483         for_each_task(p)
 484                 if (p->session == current->session)
 485                         p->tty = NULL;
 486 }
 487 
 488 /*
 489  * Sometimes we want to wait until a particular VT has been activated. We
 490  * do it in a very simple manner. Everybody waits on a single queue and
 491  * get woken up at once. Those that are satisfied go on with their business,
 492  * while those not ready go back to sleep. Seems overkill to add a wait
 493  * to each vt just for this - usually this does nothing!
 494  */
 495 static struct wait_queue *vt_activate_queue = NULL;
 496 
 497 /*
 498  * Sleeps until a vt is activated, or the task is interrupted. Returns
 499  * 0 if activation, -1 if interrupted.
 500  */
 501 int vt_waitactive(void)
     /*  */
 502 {
 503         interruptible_sleep_on(&vt_activate_queue);
 504         return (current->signal & ~current->blocked) ? -1 : 0;
 505 }
 506 
 507 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 508 
 509 void reset_vc(unsigned int new_console)
     /*  */
 510 {
 511         vt_cons[new_console]->vc_mode = KD_TEXT;
 512         kbd_table[new_console].kbdmode = VC_XLATE;
 513         vt_cons[new_console]->vt_mode.mode = VT_AUTO;
 514         vt_cons[new_console]->vt_mode.waitv = 0;
 515         vt_cons[new_console]->vt_mode.relsig = 0;
 516         vt_cons[new_console]->vt_mode.acqsig = 0;
 517         vt_cons[new_console]->vt_mode.frsig = 0;
 518         vt_cons[new_console]->vt_pid = -1;
 519         vt_cons[new_console]->vt_newvt = -1;
 520         reset_palette (new_console) ;
 521 }
 522 
 523 /*
 524  * Performs the back end of a vt switch
 525  */
 526 void complete_change_console(unsigned int new_console)
     /*  */
 527 {
 528         unsigned char old_vc_mode;
 529 
 530         if ((new_console == fg_console) || (vt_dont_switch))
 531                 return;
 532         if (!vc_cons_allocated(new_console))
 533                 return;
 534         last_console = fg_console;
 535 
 536         /*
 537          * If we're switching, we could be going from KD_GRAPHICS to
 538          * KD_TEXT mode or vice versa, which means we need to blank or
 539          * unblank the screen later.
 540          */
 541         old_vc_mode = vt_cons[fg_console]->vc_mode;
 542         update_screen(new_console);
 543 
 544         /*
 545          * If this new console is under process control, send it a signal
 546          * telling it that it has acquired. Also check if it has died and
 547          * clean up (similar to logic employed in change_console())
 548          */
 549         if (vt_cons[new_console]->vt_mode.mode == VT_PROCESS)
 550         {
 551                 /*
 552                  * Send the signal as privileged - kill_proc() will
 553                  * tell us if the process has gone or something else
 554                  * is awry
 555                  */
 556                 if (kill_proc(vt_cons[new_console]->vt_pid,
 557                               vt_cons[new_console]->vt_mode.acqsig,
 558                               1) != 0)
 559                 {
 560                 /*
 561                  * The controlling process has died, so we revert back to
 562                  * normal operation. In this case, we'll also change back
 563                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 564                  * but it saves the agony when the X server dies and the screen
 565                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 566                  * this outside of VT_PROCESS but there is no single process
 567                  * to account for and tracking tty count may be undesirable.
 568                  */
 569                         reset_vc(new_console);
 570                 }
 571         }
 572 
 573         /*
 574          * We do this here because the controlling process above may have
 575          * gone, and so there is now a new vc_mode
 576          */
 577         if (old_vc_mode != vt_cons[new_console]->vc_mode)
 578         {
 579                 if (vt_cons[new_console]->vc_mode == KD_TEXT)
 580                         do_unblank_screen();
 581                 else
 582                         do_blank_screen(1);
 583         }
 584 
 585         /* Set the colour palette for this VT */
 586         if (vt_cons[new_console]->vc_mode == KD_TEXT)
 587                 set_palette() ;
 588         
 589         /*
 590          * Wake anyone waiting for their VT to activate
 591          */
 592         vt_wake_waitactive();
 593         return;
 594 }
 595 
 596 /*
 597  * Performs the front-end of a vt switch
 598  */
 599 void change_console(unsigned int new_console)
     /*  */
 600 {
 601         if ((new_console == fg_console) || (vt_dont_switch))
 602                 return;
 603         if (!vc_cons_allocated(new_console))
 604                 return;
 605 
 606         /*
 607          * If this vt is in process mode, then we need to handshake with
 608          * that process before switching. Essentially, we store where that
 609          * vt wants to switch to and wait for it to tell us when it's done
 610          * (via VT_RELDISP ioctl).
 611          *
 612          * We also check to see if the controlling process still exists.
 613          * If it doesn't, we reset this vt to auto mode and continue.
 614          * This is a cheap way to track process control. The worst thing
 615          * that can happen is: we send a signal to a process, it dies, and
 616          * the switch gets "lost" waiting for a response; hopefully, the
 617          * user will try again, we'll detect the process is gone (unless
 618          * the user waits just the right amount of time :-) and revert the
 619          * vt to auto control.
 620          */
 621         if (vt_cons[fg_console]->vt_mode.mode == VT_PROCESS)
 622         {
 623                 /*
 624                  * Send the signal as privileged - kill_proc() will
 625                  * tell us if the process has gone or something else
 626                  * is awry
 627                  */
 628                 if (kill_proc(vt_cons[fg_console]->vt_pid,
 629                               vt_cons[fg_console]->vt_mode.relsig,
 630                               1) == 0)
 631                 {
 632                         /*
 633                          * It worked. Mark the vt to switch to and
 634                          * return. The process needs to send us a
 635                          * VT_RELDISP ioctl to complete the switch.
 636                          */
 637                         vt_cons[fg_console]->vt_newvt = new_console;
 638                         return;
 639                 }
 640 
 641                 /*
 642                  * The controlling process has died, so we revert back to
 643                  * normal operation. In this case, we'll also change back
 644                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 645                  * but it saves the agony when the X server dies and the screen
 646                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 647                  * this outside of VT_PROCESS but there is no single process
 648                  * to account for and tracking tty count may be undesirable.
 649                  */
 650                 reset_vc(fg_console);
 651 
 652                 /*
 653                  * Fall through to normal (VT_AUTO) handling of the switch...
 654                  */
 655         }
 656 
 657         /*
 658          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 659          */
 660         if (vt_cons[fg_console]->vc_mode == KD_GRAPHICS)
 661                 return;
 662 
 663         complete_change_console(new_console);
 664 }
 665 
 666 void wait_for_keypress(void)
     /*  */
 667 {
 668         sleep_on(&keypress_wait);
 669 }
 670 
 671 void stop_tty(struct tty_struct *tty)
     /*  */
 672 {
 673         if (tty->stopped)
 674                 return;
 675         tty->stopped = 1;
 676         if (tty->link && tty->link->packet) {
 677                 tty->ctrl_status &= ~TIOCPKT_START;
 678                 tty->ctrl_status |= TIOCPKT_STOP;
 679                 wake_up_interruptible(&tty->link->read_wait);
 680         }
 681         if (tty->driver.stop)
 682                 (tty->driver.stop)(tty);
 683 }
 684 
 685 void start_tty(struct tty_struct *tty)
     /*  */
 686 {
 687         if (!tty->stopped)
 688                 return;
 689         tty->stopped = 0;
 690         if (tty->link && tty->link->packet) {
 691                 tty->ctrl_status &= ~TIOCPKT_STOP;
 692                 tty->ctrl_status |= TIOCPKT_START;
 693                 wake_up_interruptible(&tty->link->read_wait);
 694         }
 695         if (tty->driver.start)
 696                 (tty->driver.start)(tty);
 697         if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
 698             tty->ldisc.write_wakeup)
 699                 (tty->ldisc.write_wakeup)(tty);
 700         wake_up_interruptible(&tty->write_wait);
 701 }
 702 
 703 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 704 {
 705         int i;
 706         struct tty_struct * tty;
 707 
 708         tty = (struct tty_struct *)file->private_data;
 709         if (tty_paranoia_check(tty, inode->i_rdev, "tty_read"))
 710                 return -EIO;
 711         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 712                 return -EIO;
 713 
 714         /* This check not only needs to be done before reading, but also
 715            whenever read_chan() gets woken up after sleeping, so I've
 716            moved it to there.  This should only be done for the N_TTY
 717            line discipline, anyway.  Same goes for write_chan(). -- jlc. */
 718 #if 0
 719         if ((inode->i_rdev != CONSOLE_DEV) && /* don't stop on /dev/console */
 720             (tty->pgrp > 0) &&
 721             (current->tty == tty) &&
 722             (tty->pgrp != current->pgrp))
 723                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 724                         return -EIO;
 725                 else {
 726                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 727                         return -ERESTARTSYS;
 728                 }
 729 #endif
 730         if (tty->ldisc.read)
 731                 /* XXX casts are for what kernel-wide prototypes should be. */
 732                 i = (tty->ldisc.read)(tty,file,(unsigned char *)buf,(unsigned int)count);
 733         else
 734                 i = -EIO;
 735         if (i > 0)
 736                 inode->i_atime = CURRENT_TIME;
 737         return i;
 738 }
 739 
 740 static int tty_write(struct inode * inode, struct file * file, const char * buf, int count)
     /*  */
 741 {
 742         int i, is_console;
 743         struct tty_struct * tty;
 744 
 745         is_console = (inode->i_rdev == CONSOLE_DEV);
 746 
 747         if (is_console && redirect)
 748                 tty = redirect;
 749         else
 750                 tty = (struct tty_struct *)file->private_data;
 751         if (tty_paranoia_check(tty, inode->i_rdev, "tty_write"))
 752                 return -EIO;
 753         if (!tty || !tty->driver.write || (tty->flags & (1 << TTY_IO_ERROR)))
 754                 return -EIO;
 755 #if 0
 756         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
 757             (current->tty == tty) && (tty->pgrp != current->pgrp)) {
 758                 if (is_orphaned_pgrp(current->pgrp))
 759                         return -EIO;
 760                 if (!is_ignored(SIGTTOU)) {
 761                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
 762                         return -ERESTARTSYS;
 763                 }
 764         }
 765 #endif
 766         if (tty->ldisc.write)
 767                 /* XXX casts are for what kernel-wide prototypes should be. */
 768                 i = (tty->ldisc.write)(tty,file,(const unsigned char *)buf,(unsigned int)count);
 769         else
 770                 i = -EIO;
 771         if (i > 0)
 772                 inode->i_mtime = CURRENT_TIME;
 773         return i;
 774 }
 775 
 776 /*
 777  * This is so ripe with races that you should *really* not touch this
 778  * unless you know exactly what you are doing. All the changes have to be
 779  * made atomically, or there may be incorrect pointers all over the place.
 780  */
 781 static int init_dev(kdev_t device, struct tty_struct **ret_tty)
     /*  */
 782 {
 783         struct tty_struct *tty, **tty_loc, *o_tty, **o_tty_loc;
 784         struct termios *tp, **tp_loc, *o_tp, **o_tp_loc;
 785         struct termios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
 786         struct tty_driver *driver;      
 787         int retval;
 788         int idx;
 789 
 790         driver = get_tty_driver(device);
 791         if (!driver)
 792                 return -ENODEV;
 793 
 794         idx = MINOR(device) - driver->minor_start;
 795         tty = o_tty = NULL;
 796         tp = o_tp = NULL;
 797         ltp = o_ltp = NULL;
 798         o_tty_loc = NULL;
 799         o_tp_loc = o_ltp_loc = NULL;
 800 
 801         tty_loc = &driver->table[idx];
 802         tp_loc = &driver->termios[idx];
 803         ltp_loc = &driver->termios_locked[idx];
 804 
 805 repeat:
 806         retval = -EAGAIN;
 807         if (driver->type == TTY_DRIVER_TYPE_PTY &&
 808             driver->subtype == PTY_TYPE_MASTER &&
 809             *tty_loc && (*tty_loc)->count)
 810                 goto end_init;
 811         retval = -ENOMEM;
 812         if (!*tty_loc && !tty) {
 813                 if (!(tty = (struct tty_struct*) get_free_page(GFP_KERNEL)))
 814                         goto end_init;
 815                 initialize_tty_struct(tty);
 816                 tty->device = device;
 817                 tty->driver = *driver;
 818                 goto repeat;
 819         }
 820         if (!*tp_loc && !tp) {
 821                 tp = (struct termios *) kmalloc(sizeof(struct termios),
 822                                                 GFP_KERNEL);
 823                 if (!tp)
 824                         goto end_init;
 825                 *tp = driver->init_termios;
 826                 goto repeat;
 827         }
 828         if (!*ltp_loc && !ltp) {
 829                 ltp = (struct termios *) kmalloc(sizeof(struct termios),
 830                                                  GFP_KERNEL);
 831                 if (!ltp)
 832                         goto end_init;
 833                 memset(ltp, 0, sizeof(struct termios));
 834                 goto repeat;
 835         }
 836         if (driver->type == TTY_DRIVER_TYPE_PTY) {
 837                 o_tty_loc = &driver->other->table[idx];
 838                 o_tp_loc = &driver->other->termios[idx];
 839                 o_ltp_loc = &driver->other->termios_locked[idx];
 840 
 841                 if (!*o_tty_loc && !o_tty) {
 842                         kdev_t  o_device;
 843                         
 844                         o_tty = (struct tty_struct *)
 845                                 get_free_page(GFP_KERNEL);
 846                         if (!o_tty)
 847                                 goto end_init;
 848                         o_device = MKDEV(driver->other->major,
 849                                          driver->other->minor_start + idx);
 850                         initialize_tty_struct(o_tty);
 851                         o_tty->device = o_device;
 852                         o_tty->driver = *driver->other;
 853                         goto repeat;
 854                 }
 855                 if (!*o_tp_loc && !o_tp) {
 856                         o_tp = (struct termios *)
 857                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
 858                         if (!o_tp)
 859                                 goto end_init;
 860                         *o_tp = driver->other->init_termios;
 861                         goto repeat;
 862                 }
 863                 if (!*o_ltp_loc && !o_ltp) {
 864                         o_ltp = (struct termios *)
 865                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
 866                         if (!o_ltp)
 867                                 goto end_init;
 868                         memset(o_ltp, 0, sizeof(struct termios));
 869                         goto repeat;
 870                 }
 871                 
 872         }
 873         /* Now we have allocated all the structures: update all the pointers.. */
 874         if (!*tp_loc) {
 875                 *tp_loc = tp;
 876                 tp = NULL;
 877         }
 878         if (!*ltp_loc) {
 879                 *ltp_loc = ltp;
 880                 ltp = NULL;
 881         }
 882         if (!*tty_loc) {
 883                 tty->termios = *tp_loc;
 884                 tty->termios_locked = *ltp_loc;
 885                 *tty_loc = tty;
 886                 (*driver->refcount)++;
 887                 (*tty_loc)->count++;
 888                 if (tty->ldisc.open) {
 889                         retval = (tty->ldisc.open)(tty);
 890                         if (retval < 0) {
 891                                 (*tty_loc)->count--;
 892                                 tty = NULL;
 893                                 goto end_init;
 894                         }
 895                 }
 896                 tty = NULL;
 897         } else {
 898                 if ((*tty_loc)->flags & (1 << TTY_CLOSING)) {
 899                         printk("Attempt to open closing tty %s.\n",
 900                                tty_name(*tty_loc));
 901                         printk("Ack!!!!  This should never happen!!\n");
 902                         return -EINVAL;
 903                 }
 904                 (*tty_loc)->count++;
 905         }
 906         if (driver->type == TTY_DRIVER_TYPE_PTY) {
 907                 if (!*o_tp_loc) {
 908                         *o_tp_loc = o_tp;
 909                         o_tp = NULL;
 910                 }
 911                 if (!*o_ltp_loc) {
 912                         *o_ltp_loc = o_ltp;
 913                         o_ltp = NULL;
 914                 }
 915                 if (!*o_tty_loc) {
 916                         o_tty->termios = *o_tp_loc;
 917                         o_tty->termios_locked = *o_ltp_loc;
 918                         *o_tty_loc = o_tty;
 919                         (*driver->other->refcount)++;
 920                         if (o_tty->ldisc.open) {
 921                                 retval = (o_tty->ldisc.open)(o_tty);
 922                                 if (retval < 0) {
 923                                         (*tty_loc)->count--;
 924                                         o_tty = NULL;
 925                                         goto end_init;
 926                                 }
 927                         }
 928                         o_tty = NULL;
 929                 }
 930                 (*tty_loc)->link = *o_tty_loc;
 931                 (*o_tty_loc)->link = *tty_loc;
 932                 if (driver->subtype == PTY_TYPE_MASTER)
 933                         (*o_tty_loc)->count++;
 934         }
 935         (*tty_loc)->driver = *driver;
 936         *ret_tty = *tty_loc;
 937         retval = 0;
 938 end_init:
 939         if (tty)
 940                 free_page((unsigned long) tty);
 941         if (o_tty)
 942                 free_page((unsigned long) o_tty);
 943         if (tp)
 944                 kfree_s(tp, sizeof(struct termios));
 945         if (o_tp)
 946                 kfree_s(o_tp, sizeof(struct termios));
 947         if (ltp)
 948                 kfree_s(ltp, sizeof(struct termios));
 949         if (o_ltp)
 950                 kfree_s(o_ltp, sizeof(struct termios));
 951         return retval;
 952 }
 953 
 954 /*
 955  * Even releasing the tty structures is a tricky business.. We have
 956  * to be very careful that the structures are all released at the
 957  * same time, as interrupts might otherwise get the wrong pointers.
 958  */
 959 static void release_dev(struct file * filp)
     /*  */
 960 {
 961         struct tty_struct *tty, *o_tty;
 962         struct termios *tp, *o_tp, *ltp, *o_ltp;
 963         struct task_struct **p;
 964         int     idx;
 965         
 966         tty = (struct tty_struct *)filp->private_data;
 967         if (tty_paranoia_check(tty, filp->f_inode->i_rdev, "release_dev"))
 968                 return;
 969 
 970         check_tty_count(tty, "release_dev");
 971 
 972         tty_fasync(filp->f_inode, filp, 0);
 973 
 974         tp = tty->termios;
 975         ltp = tty->termios_locked;
 976 
 977         idx = MINOR(tty->device) - tty->driver.minor_start;
 978 #ifdef TTY_PARANOIA_CHECK
 979         if (idx < 0 || idx >= tty->driver.num) {
 980                 printk("release_dev: bad idx when trying to free (%s)\n",
 981                        kdevname(tty->device));
 982                 return;
 983         }
 984         if (tty != tty->driver.table[idx]) {
 985                 printk("release_dev: driver.table[%d] not tty for (%s)\n",
 986                        idx, kdevname(tty->device));
 987                 return;
 988         }
 989         if (tp != tty->driver.termios[idx]) {
 990                 printk("release_dev: driver.termios[%d] not termios for ("
 991                        "%s)\n",
 992                        idx, kdevname(tty->device));
 993                 return;
 994         }
 995         if (ltp != tty->driver.termios_locked[idx]) {
 996                 printk("release_dev: driver.termios_locked[%d] not termios_locked for ("
 997                        "%s)\n",
 998                        idx, kdevname(tty->device));
 999                 return;
1000         }
1001 #endif
1002 
1003 #ifdef TTY_DEBUG_HANGUP
1004         printk("release_dev of %s (tty count=%d)...", tty_name(tty),
1005                tty->count);
1006 #endif
1007 
1008         o_tty = tty->link;
1009         o_tp = (o_tty) ? o_tty->termios : NULL;
1010         o_ltp = (o_tty) ? o_tty->termios_locked : NULL;
1011 
1012 #ifdef TTY_PARANOIA_CHECK
1013         if (tty->driver.other) {
1014                 if (o_tty != tty->driver.other->table[idx]) {
1015                         printk("release_dev: other->table[%d] not o_tty for ("
1016                                "%s)\n",
1017                                idx, kdevname(tty->device));
1018                         return;
1019                 }
1020                 if (o_tp != tty->driver.other->termios[idx]) {
1021                         printk("release_dev: other->termios[%d] not o_termios for ("
1022                                "%s)\n",
1023                                idx, kdevname(tty->device));
1024                         return;
1025                 }
1026                 if (o_ltp != tty->driver.other->termios_locked[idx]) {
1027                         printk("release_dev: other->termios_locked[%d] not o_termios_locked for ("
1028                                "%s)\n",
1029                                idx, kdevname(tty->device));
1030                         return;
1031                 }
1032 
1033                 if (o_tty->link != tty) {
1034                         printk("release_dev: bad pty pointers\n");
1035                         return;
1036                 }
1037         }
1038 #endif
1039         
1040         if (tty->driver.close)
1041                 tty->driver.close(tty, filp);
1042         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1043             tty->driver.subtype == PTY_TYPE_MASTER) {
1044                 if (--tty->link->count < 0) {
1045                         printk("release_dev: bad pty slave count (%d) for %s\n",
1046                                tty->count, tty_name(tty));
1047                         tty->link->count = 0;
1048                 }
1049         }
1050         if (--tty->count < 0) {
1051                 printk("release_dev: bad tty->count (%d) for %s\n",
1052                        tty->count, tty_name(tty));
1053                 tty->count = 0;
1054         }
1055         if (tty->count)
1056                 return;
1057 
1058         /*
1059          * We're committed; at this point, we must not block!
1060          */
1061         if (o_tty) {
1062                 if (o_tty->count)
1063                         return;
1064                 tty->driver.other->table[idx] = NULL;
1065                 tty->driver.other->termios[idx] = NULL;
1066                 kfree_s(o_tp, sizeof(struct termios));
1067         }
1068         
1069 #ifdef TTY_DEBUG_HANGUP
1070         printk("freeing tty structure...");
1071 #endif
1072         tty->flags |= (1 << TTY_CLOSING);
1073 
1074         /*
1075          * Make sure there aren't any processes that still think this
1076          * tty is their controlling tty.
1077          */
1078         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1079                 if (*p == 0)
1080                         continue;
1081                 if ((*p)->tty == tty)
1082                         (*p)->tty = NULL;
1083                 if (o_tty && (*p)->tty == o_tty)
1084                         (*p)->tty = NULL;
1085         }
1086 
1087         /*
1088          * Shutdown the current line discipline, and reset it to
1089          * N_TTY.
1090          */
1091         if (tty->ldisc.close)
1092                 (tty->ldisc.close)(tty);
1093         tty->ldisc = ldiscs[N_TTY];
1094         tty->termios->c_line = N_TTY;
1095         if (o_tty) {
1096                 if (o_tty->ldisc.close)
1097                         (o_tty->ldisc.close)(o_tty);
1098                 o_tty->ldisc = ldiscs[N_TTY];
1099         }
1100         
1101         tty->driver.table[idx] = NULL;
1102         if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS) {
1103                 tty->driver.termios[idx] = NULL;
1104                 kfree_s(tp, sizeof(struct termios));
1105         }
1106         if (tty == redirect || o_tty == redirect)
1107                 redirect = NULL;
1108         /*
1109          * Make sure that the tty's task queue isn't activated.  If it
1110          * is, take it out of the linked list.
1111          */
1112         cli();
1113         if (tty->flip.tqueue.sync) {
1114                 struct tq_struct *tq, *prev;
1115 
1116                 for (tq=tq_timer, prev=0; tq; prev=tq, tq=tq->next) {
1117                         if (tq == &tty->flip.tqueue) {
1118                                 if (prev)
1119                                         prev->next = tq->next;
1120                                 else
1121                                         tq_timer = tq->next;
1122                                 break;
1123                         }
1124                 }
1125         }
1126         sti();
1127         tty->magic = 0;
1128         (*tty->driver.refcount)--;
1129         free_page((unsigned long) tty);
1130         filp->private_data = 0;
1131         if (o_tty) {
1132                 o_tty->magic = 0;
1133                 (*o_tty->driver.refcount)--;
1134                 free_page((unsigned long) o_tty);
1135         }
1136 }
1137 
1138 /*
1139  * tty_open and tty_release keep up the tty count that contains the
1140  * number of opens done on a tty. We cannot use the inode-count, as
1141  * different inodes might point to the same tty.
1142  *
1143  * Open-counting is needed for pty masters, as well as for keeping
1144  * track of serial lines: DTR is dropped when the last close happens.
1145  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1146  *
1147  * The termios state of a pty is reset on first open so that
1148  * settings don't persist across reuse.
1149  */
1150 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1151 {
1152         struct tty_struct *tty;
1153         int minor;
1154         int noctty, retval;
1155         kdev_t device;
1156 
1157 retry_open:
1158         noctty = filp->f_flags & O_NOCTTY;
1159         device = inode->i_rdev;
1160         if (device == TTY_DEV) {
1161                 if (!current->tty)
1162                         return -ENXIO;
1163                 device = current->tty->device;
1164                 /* noctty = 1; */
1165         }
1166         if (device == CONSOLE_DEV) {
1167                 device = MKDEV(TTY_MAJOR, fg_console+1);
1168                 noctty = 1;
1169         }
1170         minor = MINOR(device);
1171         
1172         retval = init_dev(device, &tty);
1173         if (retval)
1174                 return retval;
1175         filp->private_data = tty;
1176         check_tty_count(tty, "tty_open");
1177         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1178             tty->driver.subtype == PTY_TYPE_MASTER)
1179                 noctty = 1;
1180 #ifdef TTY_DEBUG_HANGUP
1181         printk("opening %s...", tty_name(tty));
1182 #endif
1183         if (tty->driver.open)
1184                 retval = tty->driver.open(tty, filp);
1185         else
1186                 retval = -ENODEV;
1187 
1188         if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !suser())
1189                 retval = -EBUSY;
1190 
1191         if (retval) {
1192 #ifdef TTY_DEBUG_HANGUP
1193                 printk("error %d in opening %s...", retval, tty_name(tty));
1194 #endif
1195 
1196                 release_dev(filp);
1197                 if (retval != -ERESTARTSYS)
1198                         return retval;
1199                 if (current->signal & ~current->blocked)
1200                         return retval;
1201                 schedule();
1202                 /*
1203                  * Need to reset f_op in case a hangup happened.
1204                  */
1205                 filp->f_op = &tty_fops;
1206                 goto retry_open;
1207         }
1208         if (!noctty &&
1209             current->leader &&
1210             !current->tty &&
1211             tty->session == 0) {
1212                 current->tty = tty;
1213                 current->tty_old_pgrp = 0;
1214                 tty->session = current->session;
1215                 tty->pgrp = current->pgrp;
1216         }
1217         return 0;
1218 }
1219 
1220 /*
1221  * Note that releasing a pty master also releases the child, so
1222  * we have to make the redirection checks after that and on both
1223  * sides of a pty.
1224  */
1225 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1226 {
1227         release_dev(filp);
1228 }
1229 
1230 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1231 {
1232         struct tty_struct * tty;
1233 
1234         tty = (struct tty_struct *)filp->private_data;
1235         if (tty_paranoia_check(tty, inode->i_rdev, "tty_select"))
1236                 return 0;
1237 
1238         if (tty->ldisc.select)
1239                 return (tty->ldisc.select)(tty, inode, filp, sel_type, wait);
1240         return 0;
1241 }
1242 
1243 /*
1244  * fasync_helper() is used by some character device drivers (mainly mice)
1245  * to set up the fasync queue. It returns negative on error, 0 if it did
1246  * no changes and positive if it added/deleted the entry.
1247  */
1248 int fasync_helper(struct inode * inode, struct file * filp, int on, struct fasync_struct **fapp)
     /*  */
1249 {
1250         struct fasync_struct *fa, **fp;
1251         unsigned long flags;
1252 
1253         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
1254                 if (fa->fa_file == filp)
1255                         break;
1256         }
1257 
1258         if (on) {
1259                 if (fa)
1260                         return 0;
1261                 fa = (struct fasync_struct *)kmalloc(sizeof(struct fasync_struct), GFP_KERNEL);
1262                 if (!fa)
1263                         return -ENOMEM;
1264                 fa->magic = FASYNC_MAGIC;
1265                 fa->fa_file = filp;
1266                 save_flags(flags);
1267                 cli();
1268                 fa->fa_next = *fapp;
1269                 *fapp = fa;
1270                 restore_flags(flags);
1271                 return 1;
1272         }
1273         if (!fa)
1274                 return 0;
1275         save_flags(flags);
1276         cli();
1277         *fp = fa->fa_next;
1278         restore_flags(flags);
1279         kfree(fa);
1280         return 1;
1281 }
1282 
1283 static int tty_fasync(struct inode * inode, struct file * filp, int on)
     /*  */
1284 {
1285         struct tty_struct * tty;
1286         int retval;
1287 
1288         tty = (struct tty_struct *)filp->private_data;
1289         if (tty_paranoia_check(tty, inode->i_rdev, "tty_fasync"))
1290                 return 0;
1291         
1292         retval = fasync_helper(inode, filp, on, &tty->fasync);
1293         if (retval <= 0)
1294                 return retval;
1295 
1296         if (on) {
1297                 if (!tty->read_wait)
1298                         tty->minimum_to_wake = 1;
1299                 if (filp->f_owner == 0) {
1300                         if (tty->pgrp)
1301                                 filp->f_owner = -tty->pgrp;
1302                         else
1303                                 filp->f_owner = current->pid;
1304                 }
1305         } else {
1306                 if (!tty->fasync && !tty->read_wait)
1307                         tty->minimum_to_wake = N_TTY_BUF_SIZE;
1308         }
1309         return 0;
1310 }
1311 
1312 #if 0
1313 /*
1314  * XXX does anyone use this anymore?!?
1315  */
1316 static int do_get_ps_info(unsigned long arg)
     /*  */
1317 {
1318         struct tstruct {
1319                 int flag;
1320                 int present[NR_TASKS];
1321                 struct task_struct tasks[NR_TASKS];
1322         };
1323         struct tstruct *ts = (struct tstruct *)arg;
1324         struct task_struct **p;
1325         char *c, *d;
1326         int i, n = 0;
1327         
1328         i = verify_area(VERIFY_WRITE, (void *)arg, sizeof(struct tstruct));
1329         if (i)
1330                 return i;
1331         for (p = &FIRST_TASK ; p <= &LAST_TASK ; p++, n++)
1332                 if (*p)
1333                 {
1334                         c = (char *)(*p);
1335                         d = (char *)(ts->tasks+n);
1336                         for (i=0 ; i<sizeof(struct task_struct) ; i++)
1337                                 put_user(*c++, d++);
1338                         put_user(1, ts->present+n);
1339                 }
1340                 else    
1341                         put_user(0, ts->present+n);
1342         return(0);                      
1343 }
1344 #endif
1345 
1346 static int tty_ioctl(struct inode * inode, struct file * file,
     /*  */
1347                      unsigned int cmd, unsigned long arg)
1348 {
1349         int     retval;
1350         struct tty_struct * tty;
1351         struct tty_struct * real_tty;
1352         struct winsize tmp_ws;
1353         pid_t pgrp;
1354         unsigned char   ch;
1355         char    mbz = 0;
1356         
1357         tty = (struct tty_struct *)file->private_data;
1358         if (tty_paranoia_check(tty, inode->i_rdev, "tty_ioctl"))
1359                 return -EINVAL;
1360 
1361         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1362             tty->driver.subtype == PTY_TYPE_MASTER)
1363                 real_tty = tty->link;
1364         else
1365                 real_tty = tty;
1366 
1367         switch (cmd) {
1368                 case TIOCSTI:
1369                         if ((current->tty != tty) && !suser())
1370                                 return -EPERM;
1371                         retval = verify_area(VERIFY_READ, (void *) arg, 1);
1372                         if (retval)
1373                                 return retval;
1374                         ch = get_user((char *) arg);
1375                         tty->ldisc.receive_buf(tty, &ch, &mbz, 1);
1376                         return 0;
1377                 case TIOCGWINSZ:
1378                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1379                                              sizeof (struct winsize));
1380                         if (retval)
1381                                 return retval;
1382                         memcpy_tofs((struct winsize *) arg, &tty->winsize,
1383                                     sizeof (struct winsize));
1384                         return 0;
1385                 case TIOCSWINSZ:
1386                         retval = verify_area(VERIFY_READ, (void *) arg,
1387                                              sizeof (struct winsize));
1388                         if (retval)
1389                                 return retval;                  
1390                         memcpy_fromfs(&tmp_ws, (struct winsize *) arg,
1391                                       sizeof (struct winsize));
1392                         if (memcmp(&tmp_ws, &tty->winsize,
1393                                    sizeof(struct winsize))) {
1394                                 if (tty->pgrp > 0)
1395                                         kill_pg(tty->pgrp, SIGWINCH, 1);
1396                                 if ((real_tty->pgrp != tty->pgrp) &&
1397                                     (real_tty->pgrp > 0))
1398                                         kill_pg(real_tty->pgrp, SIGWINCH, 1);
1399                         }
1400                         tty->winsize = tmp_ws;
1401                         real_tty->winsize = tmp_ws;
1402                         return 0;
1403                 case TIOCCONS:
1404                         if (tty->driver.type == TTY_DRIVER_TYPE_CONSOLE) {
1405                                 if (!suser())
1406                                         return -EPERM;
1407                                 redirect = NULL;
1408                                 return 0;
1409                         }
1410                         if (redirect)
1411                                 return -EBUSY;
1412                         redirect = real_tty;
1413                         return 0;
1414                 case FIONBIO:
1415                         retval = verify_area(VERIFY_READ, (void *) arg, sizeof(int));
1416                         if (retval)
1417                                 return retval;
1418                         arg = get_user((unsigned int *) arg);
1419                         if (arg)
1420                                 file->f_flags |= O_NONBLOCK;
1421                         else
1422                                 file->f_flags &= ~O_NONBLOCK;
1423                         return 0;
1424                 case TIOCEXCL:
1425                         set_bit(TTY_EXCLUSIVE, &tty->flags);
1426                         return 0;
1427                 case TIOCNXCL:
1428                         clear_bit(TTY_EXCLUSIVE, &tty->flags);
1429                         return 0;
1430                 case TIOCNOTTY:
1431                         if (current->tty != tty)
1432                                 return -ENOTTY;
1433                         if (current->leader)
1434                                 disassociate_ctty(0);
1435                         current->tty = NULL;
1436                         return 0;
1437                 case TIOCSCTTY:
1438                         if (current->leader &&
1439                             (current->session == tty->session))
1440                                 return 0;
1441                         /*
1442                          * The process must be a session leader and
1443                          * not have a controlling tty already.
1444                          */
1445                         if (!current->leader || current->tty)
1446                                 return -EPERM;
1447                         if (tty->session > 0) {
1448                                 /*
1449                                  * This tty is already the controlling
1450                                  * tty for another session group!
1451                                  */
1452                                 if ((arg == 1) && suser()) {
1453                                         /*
1454                                          * Steal it away
1455                                          */
1456                                         struct task_struct *p;
1457 
1458                                         for_each_task(p)
1459                                                 if (p->tty == tty)
1460                                                         p->tty = NULL;
1461                                 } else
1462                                         return -EPERM;
1463                         }
1464                         current->tty = tty;
1465                         current->tty_old_pgrp = 0;
1466                         tty->session = current->session;
1467                         tty->pgrp = current->pgrp;
1468                         return 0;
1469                 case TIOCGPGRP:
1470                         /*
1471                          * (tty == real_tty) is a cheap way of
1472                          * testing if the tty is NOT a master pty.
1473                          */
1474                         if (tty == real_tty && current->tty != real_tty)
1475                                 return -ENOTTY;
1476                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1477                                              sizeof (pid_t));
1478                         if (retval)
1479                                 return retval;
1480                         put_user(real_tty->pgrp, (pid_t *) arg);
1481                         return 0;
1482                 case TIOCSPGRP:
1483                         retval = tty_check_change(real_tty);
1484                         if (retval)
1485                                 return retval;
1486                         if (!current->tty ||
1487                             (current->tty != real_tty) ||
1488                             (real_tty->session != current->session))
1489                                 return -ENOTTY;
1490                         pgrp = get_user((pid_t *) arg);
1491                         if (pgrp < 0)
1492                                 return -EINVAL;
1493                         if (session_of_pgrp(pgrp) != current->session)
1494                                 return -EPERM;
1495                         real_tty->pgrp = pgrp;
1496                         return 0;
1497                 case TIOCGETD:
1498                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1499                                              sizeof (int));
1500                         if (retval)
1501                                 return retval;
1502                         put_user(tty->ldisc.num, (int *) arg);
1503                         return 0;
1504                 case TIOCSETD:
1505                         retval = tty_check_change(tty);
1506                         if (retval)
1507                                 return retval;
1508                         arg = get_user((int *) arg);
1509                         return tty_set_ldisc(tty, arg);
1510                 case TIOCLINUX:
1511                         if (tty->driver.type != TTY_DRIVER_TYPE_CONSOLE)
1512                                 return -EINVAL;
1513                         if (current->tty != tty && !suser())
1514                                 return -EPERM;
1515                         retval = verify_area(VERIFY_READ, (void *) arg, 1);
1516                         if (retval)
1517                                 return retval;
1518                         switch (retval = get_user((char *)arg))
1519                         {
1520                                 case 0:
1521                                 case 8:
1522                                 case 9:
1523                                         printk("TIOCLINUX (0/8/9) ioctl is gone - use /dev/vcs\n");
1524                                         return -EINVAL;
1525 #if 0
1526                                 case 1:
1527                                         printk("Deprecated TIOCLINUX (1) ioctl\n");
1528                                         return do_get_ps_info(arg);
1529 #endif
1530                                 case 2:
1531                                         return set_selection(arg, tty);
1532                                 case 3:
1533                                         return paste_selection(tty);
1534                                 case 4:
1535                                         do_unblank_screen();
1536                                         return 0;
1537                                 case 5:
1538                                         return sel_loadlut(arg);
1539                                 case 6:
1540                         /*
1541                          * Make it possible to react to Shift+Mousebutton.
1542                          * Note that 'shift_state' is an undocumented
1543                          * kernel-internal variable; programs not closely
1544                          * related to the kernel should not use this.
1545                          */
1546                                         put_user(shift_state,(char *) arg);
1547                                         return 0;
1548                                 case 7:
1549                                         put_user(mouse_reporting(),(char *) arg);
1550                                         return 0;
1551                                 case 10:
1552                                         set_vesa_blanking(arg);
1553                                         return 0;
1554                                 case 11:        /* set kmsg redirect */
1555                                         if (!suser())
1556                                                 return -EPERM;
1557                                         retval = verify_area(VERIFY_READ,
1558                                                 (void *) arg+1, 1);
1559                                         if (retval)
1560                                                 return retval;
1561                                         kmsg_redirect = get_user((char *)arg+1);
1562                                         return 0;
1563                                 case 12:        /* get fg_console */
1564                                         return fg_console;
1565                                 default: 
1566                                         return -EINVAL;
1567                         }
1568 
1569                 case TIOCTTYGSTRUCT:
1570                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1571                                                 sizeof(struct tty_struct));
1572                         if (retval)
1573                                 return retval;
1574                         memcpy_tofs((struct tty_struct *) arg,
1575                                     tty, sizeof(struct tty_struct));
1576                         return 0;
1577                 default:
1578                         if (tty->driver.ioctl) {
1579                                 retval = (tty->driver.ioctl)(tty, file,
1580                                                              cmd, arg);
1581                                 if (retval != -ENOIOCTLCMD)
1582                                         return retval;
1583                         }
1584                         if (tty->ldisc.ioctl) {
1585                                 retval = (tty->ldisc.ioctl)(tty, file,
1586                                                             cmd, arg);
1587                                 if (retval != -ENOIOCTLCMD)
1588                                         return retval;
1589                         }
1590                         return -EINVAL;
1591                 }
1592 }
1593 
1594 
1595 /*
1596  * This implements the "Secure Attention Key" ---  the idea is to
1597  * prevent trojan horses by killing all processes associated with this
1598  * tty when the user hits the "Secure Attention Key".  Required for
1599  * super-paranoid applications --- see the Orange Book for more details.
1600  * 
1601  * This code could be nicer; ideally it should send a HUP, wait a few
1602  * seconds, then send a INT, and then a KILL signal.  But you then
1603  * have to coordinate with the init process, since all processes associated
1604  * with the current tty must be dead before the new getty is allowed
1605  * to spawn.
1606  */
1607 void do_SAK( struct tty_struct *tty)
     /*  */
1608 {
1609 #ifdef TTY_SOFT_SAK
1610         tty_hangup(tty);
1611 #else
1612         struct task_struct **p;
1613         int session;
1614         int             i;
1615         struct file     *filp;
1616         
1617         if (!tty)
1618                 return;
1619         session  = tty->session;
1620         if (tty->ldisc.flush_buffer)
1621                 tty->ldisc.flush_buffer(tty);
1622         if (tty->driver.flush_buffer)
1623                 tty->driver.flush_buffer(tty);
1624         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1625                 if (!(*p))
1626                         continue;
1627                 if (((*p)->tty == tty) ||
1628                     ((session > 0) && ((*p)->session == session)))
1629                         send_sig(SIGKILL, *p, 1);
1630                 else {
1631                         for (i=0; i < NR_OPEN; i++) {
1632                                 filp = (*p)->files->fd[i];
1633                                 if (filp && (filp->f_op == &tty_fops) &&
1634                                     (filp->private_data == tty)) {
1635                                         send_sig(SIGKILL, *p, 1);
1636                                         break;
1637                                 }
1638                         }
1639                 }
1640         }
1641 #endif
1642 }
1643 
1644 /*
1645  * This routine is called out of the software interrupt to flush data
1646  * from the flip buffer to the line discipline.
1647  */
1648 static void flush_to_ldisc(void *private_)
     /*  */
1649 {
1650         struct tty_struct *tty = (struct tty_struct *) private_;
1651         unsigned char   *cp;
1652         char            *fp;
1653         int             count;
1654 
1655         if (tty->flip.buf_num) {
1656                 cp = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
1657                 fp = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
1658                 tty->flip.buf_num = 0;
1659 
1660                 cli();
1661                 tty->flip.char_buf_ptr = tty->flip.char_buf;
1662                 tty->flip.flag_buf_ptr = tty->flip.flag_buf;
1663         } else {
1664                 cp = tty->flip.char_buf;
1665                 fp = tty->flip.flag_buf;
1666                 tty->flip.buf_num = 1;
1667 
1668                 cli();
1669                 tty->flip.char_buf_ptr = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
1670                 tty->flip.flag_buf_ptr = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
1671         }
1672         count = tty->flip.count;
1673         tty->flip.count = 0;
1674         sti();
1675         
1676 #if 0
1677         if (count > tty->max_flip_cnt)
1678                 tty->max_flip_cnt = count;
1679 #endif
1680         tty->ldisc.receive_buf(tty, cp, fp, count);
1681 }
1682 
1683 /*
1684  * This subroutine initializes a tty structure.
1685  */
1686 static void initialize_tty_struct(struct tty_struct *tty)
     /*  */
1687 {
1688         memset(tty, 0, sizeof(struct tty_struct));
1689         tty->magic = TTY_MAGIC;
1690         tty->ldisc = ldiscs[N_TTY];
1691         tty->pgrp = -1;
1692         tty->flip.char_buf_ptr = tty->flip.char_buf;
1693         tty->flip.flag_buf_ptr = tty->flip.flag_buf;
1694         tty->flip.tqueue.routine = flush_to_ldisc;
1695         tty->flip.tqueue.data = tty;
1696 }
1697 
1698 /*
1699  * The default put_char routine if the driver did not define one.
1700  */
1701 void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
     /*  */
1702 {
1703         tty->driver.write(tty, 0, &ch, 1);
1704 }
1705 
1706 /*
1707  * Called by a tty driver to register itself.
1708  */
1709 int tty_register_driver(struct tty_driver *driver)
     /*  */
1710 {
1711         int error;
1712 
1713         if (driver->flags & TTY_DRIVER_INSTALLED)
1714                 return 0;
1715 
1716         error = register_chrdev(driver->major, driver->name, &tty_fops);
1717         if (error < 0)
1718                 return error;
1719         else if(driver->major == 0)
1720                 driver->major = error;
1721 
1722         if (!driver->put_char)
1723                 driver->put_char = tty_default_put_char;
1724         
1725         driver->prev = 0;
1726         driver->next = tty_drivers;
1727         if (tty_drivers) tty_drivers->prev = driver;
1728         tty_drivers = driver;
1729         return error;
1730 }
1731 
1732 /*
1733  * Called by a tty driver to unregister itself.
1734  */
1735 int tty_unregister_driver(struct tty_driver *driver)
     /*  */
1736 {
1737         int     retval;
1738         struct tty_driver *p;
1739         int     found = 0;
1740         const char *othername = NULL;
1741         
1742         if (*driver->refcount)
1743                 return -EBUSY;
1744 
1745         for (p = tty_drivers; p; p = p->next) {
1746                 if (p == driver)
1747                         found++;
1748                 else if (p->major == driver->major)
1749                         othername = p->name;
1750         }
1751 
1752         if (othername == NULL) {
1753                 retval = unregister_chrdev(driver->major, driver->name);
1754                 if (retval)
1755                         return retval;
1756         } else
1757                 register_chrdev(driver->major, othername, &tty_fops);
1758 
1759         if (driver->prev)
1760                 driver->prev->next = driver->next;
1761         else
1762                 tty_drivers = driver->next;
1763         
1764         if (driver->next)
1765                 driver->next->prev = driver->prev;
1766 
1767         return 0;
1768 }
1769 
1770 
1771 /*
1772  * Initialize the console device. This is called *early*, so
1773  * we can't necessarily depend on lots of kernel help here.
1774  * Just do some early initializations, and do the complex setup
1775  * later.
1776  */
1777 long console_init(long kmem_start, long kmem_end)
     /*  */
1778 {
1779         /* Setup the default TTY line discipline. */
1780         memset(ldiscs, 0, sizeof(ldiscs));
1781         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1782 
1783         /*
1784          * Set up the standard termios.  Individual tty drivers may 
1785          * deviate from this; this is used as a template.
1786          */
1787         memset(&tty_std_termios, 0, sizeof(struct termios));
1788         memcpy(tty_std_termios.c_cc, INIT_C_CC, NCCS);
1789         tty_std_termios.c_iflag = ICRNL | IXON;
1790         tty_std_termios.c_oflag = OPOST | ONLCR;
1791         tty_std_termios.c_cflag = B38400 | CS8 | CREAD;
1792         tty_std_termios.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
1793                 ECHOCTL | ECHOKE | IEXTEN;
1794 
1795         /*
1796          * set up the console device so that later boot sequences can 
1797          * inform about problems etc..
1798          */
1799         return con_init(kmem_start);
1800 }
1801 
1802 /*
1803  * Ok, now we can initialize the rest of the tty devices and can count
1804  * on memory allocations, interrupts etc..
1805  */
1806 int tty_init(void)
     /*  */
1807 {
1808         if (sizeof(struct tty_struct) > PAGE_SIZE)
1809                 panic("size of tty structure > PAGE_SIZE!");
1810         kbd_init();
1811         rs_init();
1812 #ifdef CONFIG_SCC
1813         scc_init();
1814 #endif
1815 #ifdef CONFIG_CYCLADES
1816         cy_init();
1817 #endif
1818 #ifdef CONFIG_STALLION
1819         stl_init();
1820 #endif
1821 #ifdef CONFIG_ISTALLION
1822         stli_init();
1823 #endif
1824         pty_init();
1825         vcs_init();
1826         if (register_chrdev(TTY_MAJOR,"tty",&tty_fops))
1827                 panic("unable to get major %d for tty device", TTY_MAJOR);
1828         if (register_chrdev(TTYAUX_MAJOR,"cua",&tty_fops))
1829                 panic("unable to get major %d for tty device", TTYAUX_MAJOR);
1830 
1831         return 0;
1832 }
/* */
root/drivers/char/tty_io.c

DEFINITIONS
