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 #ifdef CONFIG_KERNELD
  77 #include <linux/kerneld.h>
  78 #endif
  79 
  80 #define CONSOLE_DEV MKDEV(TTY_MAJOR,0)
  81 #define TTY_DEV MKDEV(TTYAUX_MAJOR,0)
  82 
  83 #undef TTY_DEBUG_HANGUP
  84 
  85 #define TTY_PARANOIA_CHECK
  86 #define CHECK_TTY_COUNT
  87 
  88 extern void do_blank_screen(int nopowersave);
  89 extern void set_vesa_blanking(const unsigned long arg);
  90 
  91 struct termios tty_std_termios;         /* for the benefit of tty drivers  */
  92 struct tty_driver *tty_drivers = NULL;  /* linked list of tty drivers */
  93 struct tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
  94 
  95 /*
  96  * fg_console is the current virtual console,
  97  * last_console is the last used one,
  98  * kmsg_redirect is the console for kernel messages,
  99  * redirect is the pseudo-tty that console output
 100  * is redirected to if asked by TIOCCONS.
 101  */
 102 int fg_console = 0;
 103 int last_console = 0;
 104 int kmsg_redirect = 0;
 105 struct tty_struct * redirect = NULL;
 106 struct wait_queue * keypress_wait = NULL;
 107 char vt_dont_switch = 0;
 108 
 109 static void initialize_tty_struct(struct tty_struct *tty);
 110 
 111 static int tty_read(struct inode *, struct file *, char *, int);
 112 static int tty_write(struct inode *, struct file *, const char *, int);
 113 static int tty_select(struct inode *, struct file *, int, select_table *);
 114 static int tty_open(struct inode *, struct file *);
 115 static void tty_release(struct inode *, struct file *);
 116 static int tty_ioctl(struct inode * inode, struct file * file,
 117                      unsigned int cmd, unsigned long arg);
 118 static int tty_fasync(struct inode * inode, struct file * filp, int on);
 119 
 120 extern void reset_palette(int currcons) ;
 121 extern void set_palette(void) ;
 122 
 123 #ifndef MIN
 124 #define MIN(a,b)        ((a) < (b) ? (a) : (b))
 125 #endif
 126 
 127 /*
 128  * These two routines return the name of tty.  tty_name() should NOT
 129  * be used in interrupt drivers, since it's not re-entrant.  Use
 130  * _tty_name() instead.
 131  */
 132 char *_tty_name(struct tty_struct *tty, char *buf)
     /*  */
 133 {
 134         if (tty)
 135                 sprintf(buf, "%s%d", tty->driver.name,
 136                         MINOR(tty->device) - tty->driver.minor_start +
 137                         tty->driver.name_base);
 138         else
 139                 strcpy(buf, "NULL tty");
 140         return buf;
 141 }
 142 
 143 char *tty_name(struct tty_struct *tty)
     /*  */
 144 {
 145         static char buf[64];
 146 
 147         return(_tty_name(tty, buf));
 148 }
 149 
 150 inline int tty_paranoia_check(struct tty_struct *tty, kdev_t device,
     /*  */
 151                               const char *routine)
 152 {
 153 #ifdef TTY_PARANOIA_CHECK
 154         static const char *badmagic =
 155                 "Warning: bad magic number for tty struct (%s) in %s\n";
 156         static const char *badtty =
 157                 "Warning: null TTY for (%s) in %s\n";
 158 
 159         if (!tty) {
 160                 printk(badtty, kdevname(device), routine);
 161                 return 1;
 162         }
 163         if (tty->magic != TTY_MAGIC) {
 164                 printk(badmagic, kdevname(device), routine);
 165                 return 1;
 166         }
 167 #endif
 168         return 0;
 169 }
 170 
 171 static int check_tty_count(struct tty_struct *tty, const char *routine)
     /*  */
 172 {
 173 #ifdef CHECK_TTY_COUNT
 174         struct file *f;
 175         int i, count = 0;
 176         
 177         for (f = first_file, i=0; i<nr_files; i++, f = f->f_next) {
 178                 if (!f->f_count)
 179                         continue;
 180                 if (f->private_data == tty) {
 181                         count++;
 182                 }
 183         }
 184         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
 185             tty->driver.subtype == PTY_TYPE_SLAVE &&
 186             tty->link && tty->link->count)
 187                 count++;
 188         if (tty->count != count) {
 189                 printk("Warning: dev (%s) tty->count(%d) != #fd's(%d) in %s\n",
 190                        kdevname(tty->device), tty->count, count, routine);
 191                 return count;
 192        }        
 193 #endif
 194         return 0;
 195 }
 196 
 197 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
     /*  */
 198 {
 199         if (disc < N_TTY || disc >= NR_LDISCS)
 200                 return -EINVAL;
 201         
 202         if (new_ldisc) {
 203                 ldiscs[disc] = *new_ldisc;
 204                 ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
 205                 ldiscs[disc].num = disc;
 206         } else
 207                 memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
 208         
 209         return 0;
 210 }
 211 
 212 /* Set the discipline of a tty line. */
 213 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
     /*  */
 214 {
 215         int     retval = 0;
 216         struct  tty_ldisc o_ldisc;
 217 
 218         if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
 219                 return -EINVAL;
 220 #ifdef CONFIG_KERNELD
 221         /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
 222         if (!(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED)) {
 223                 char modname [20];
 224                 sprintf(modname, "tty-ldisc-%d", ldisc);
 225                 request_module (modname);
 226         }
 227 #endif
 228         if (!(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED))
 229                 return -EINVAL;
 230 
 231         if (tty->ldisc.num == ldisc)
 232                 return 0;       /* We are already in the desired discipline */
 233         o_ldisc = tty->ldisc;
 234 
 235         tty_wait_until_sent(tty, 0);
 236         
 237         /* Shutdown the current discipline. */
 238         if (tty->ldisc.close)
 239                 (tty->ldisc.close)(tty);
 240 
 241         /* Now set up the new line discipline. */
 242         tty->ldisc = ldiscs[ldisc];
 243         tty->termios->c_line = ldisc;
 244         if (tty->ldisc.open)
 245                 retval = (tty->ldisc.open)(tty);
 246         if (retval < 0) {
 247                 tty->ldisc = o_ldisc;
 248                 tty->termios->c_line = tty->ldisc.num;
 249                 if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
 250                         tty->ldisc = ldiscs[N_TTY];
 251                         tty->termios->c_line = N_TTY;
 252                         if (tty->ldisc.open) {
 253                                 int r = tty->ldisc.open(tty);
 254 
 255                                 if (r < 0)
 256                                         panic("Couldn't open N_TTY ldisc for "
 257                                               "%s --- error %d.",
 258                                               tty_name(tty), r);
 259                         }
 260                 }
 261         }
 262         if (tty->ldisc.num != o_ldisc.num && tty->driver.set_ldisc)
 263                 tty->driver.set_ldisc(tty);
 264         return retval;
 265 }
 266 
 267 /*
 268  * This routine returns a tty driver structure, given a device number
 269  */
 270 struct tty_driver *get_tty_driver(kdev_t device)
     /*  */
 271 {
 272         int     major, minor;
 273         struct tty_driver *p;
 274         
 275         minor = MINOR(device);
 276         major = MAJOR(device);
 277 
 278         for (p = tty_drivers; p; p = p->next) {
 279                 if (p->major != major)
 280                         continue;
 281                 if (minor < p->minor_start)
 282                         continue;
 283                 if (minor >= p->minor_start + p->num)
 284                         continue;
 285                 return p;
 286         }
 287         return NULL;
 288 }
 289 
 290 /*
 291  * If we try to write to, or set the state of, a terminal and we're
 292  * not in the foreground, send a SIGTTOU.  If the signal is blocked or
 293  * ignored, go ahead and perform the operation.  (POSIX 7.2)
 294  */
 295 int tty_check_change(struct tty_struct * tty)
     /*  */
 296 {
 297         if (current->tty != tty)
 298                 return 0;
 299         if (tty->pgrp <= 0) {
 300                 printk("tty_check_change: tty->pgrp <= 0!\n");
 301                 return 0;
 302         }
 303         if (current->pgrp == tty->pgrp)
 304                 return 0;
 305         if (is_ignored(SIGTTOU))
 306                 return 0;
 307         if (is_orphaned_pgrp(current->pgrp))
 308                 return -EIO;
 309         (void) kill_pg(current->pgrp,SIGTTOU,1);
 310         return -ERESTARTSYS;
 311 }
 312 
 313 static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 314 {
 315         return 0;
 316 }
 317 
 318 static int hung_up_tty_write(struct inode * inode, struct file * file, const char * buf, int count)
     /*  */
 319 {
 320         return -EIO;
 321 }
 322 
 323 static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
 324 {
 325         return 1;
 326 }
 327 
 328 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
     /*  */
 329                              unsigned int cmd, unsigned long arg)
 330 {
 331         return -EIO;
 332 }
 333 
 334 static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 335 {
 336         return -ESPIPE;
 337 }
 338 
 339 static struct file_operations tty_fops = {
 340         tty_lseek,
 341         tty_read,
 342         tty_write,
 343         NULL,           /* tty_readdir */
 344         tty_select,
 345         tty_ioctl,
 346         NULL,           /* tty_mmap */
 347         tty_open,
 348         tty_release,
 349         NULL,           /* tty_fsync */
 350         tty_fasync
 351 };
 352 
 353 static struct file_operations hung_up_tty_fops = {
 354         tty_lseek,
 355         hung_up_tty_read,
 356         hung_up_tty_write,
 357         NULL,           /* hung_up_tty_readdir */
 358         hung_up_tty_select,
 359         hung_up_tty_ioctl,
 360         NULL,           /* hung_up_tty_mmap */
 361         NULL,           /* hung_up_tty_open */
 362         tty_release,    /* hung_up_tty_release */
 363         NULL,           /* hung_up_tty_fsync  */
 364         NULL            /* hung_up_tty_fasync */
 365 };
 366 
 367 void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
     /*  */
 368 {
 369         int i;
 370         struct file * filp;
 371         struct task_struct *p;
 372 
 373         if (!tty)
 374                 return;
 375         check_tty_count(tty, "do_tty_hangup");
 376         for (filp = first_file, i=0; i<nr_files; i++, filp = filp->f_next) {
 377                 if (!filp->f_count)
 378                         continue;
 379                 if (filp->private_data != tty)
 380                         continue;
 381                 if (filp->f_inode
 382                     && filp->f_inode->i_rdev == CONSOLE_DEV)
 383                         continue;
 384                 if (filp->f_op != &tty_fops)
 385                         continue;
 386                 tty_fasync(filp->f_inode, filp, 0);
 387                 filp->f_op = fops;
 388         }
 389         
 390         if (tty->ldisc.flush_buffer)
 391                 tty->ldisc.flush_buffer(tty);
 392         if (tty->driver.flush_buffer)
 393                 tty->driver.flush_buffer(tty);
 394         if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
 395             tty->ldisc.write_wakeup)
 396                 (tty->ldisc.write_wakeup)(tty);
 397         wake_up_interruptible(&tty->write_wait);
 398         wake_up_interruptible(&tty->read_wait);
 399 
 400         /*
 401          * Shutdown the current line discipline, and reset it to
 402          * N_TTY.
 403          */
 404         if (tty->ldisc.num != ldiscs[N_TTY].num) {
 405                 if (tty->ldisc.close)
 406                         (tty->ldisc.close)(tty);
 407                 tty->ldisc = ldiscs[N_TTY];
 408                 tty->termios->c_line = N_TTY;
 409                 if (tty->ldisc.open) {
 410                         i = (tty->ldisc.open)(tty);
 411                         if (i < 0)
 412                                 printk("do_tty_hangup: N_TTY open: error %d\n",
 413                                        -i);
 414                 }
 415         }
 416         
 417         for_each_task(p) {
 418                 if ((tty->session > 0) && (p->session == tty->session) &&
 419                     p->leader) {
 420                         send_sig(SIGHUP,p,1);
 421                         send_sig(SIGCONT,p,1);
 422                         if (tty->pgrp > 0)
 423                                 p->tty_old_pgrp = tty->pgrp;
 424                 }
 425                 if (p->tty == tty)
 426                         p->tty = NULL;
 427         }
 428         tty->flags = 0;
 429         tty->session = 0;
 430         tty->pgrp = -1;
 431         tty->ctrl_status = 0;
 432         if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS)
 433                 *tty->termios = tty->driver.init_termios;
 434         if (tty->driver.hangup)
 435                 (tty->driver.hangup)(tty);
 436 }
 437 
 438 void tty_hangup(struct tty_struct * tty)
     /*  */
 439 {
 440 #ifdef TTY_DEBUG_HANGUP
 441         printk("%s hangup...\n", tty_name(tty));
 442 #endif
 443         do_tty_hangup(tty, &hung_up_tty_fops);
 444 }
 445 
 446 void tty_vhangup(struct tty_struct * tty)
     /*  */
 447 {
 448 #ifdef TTY_DEBUG_HANGUP
 449         printk("%s vhangup...\n", tty_name(tty));
 450 #endif
 451         do_tty_hangup(tty, &hung_up_tty_fops);
 452 }
 453 
 454 int tty_hung_up_p(struct file * filp)
     /*  */
 455 {
 456         return (filp->f_op == &hung_up_tty_fops);
 457 }
 458 
 459 /*
 460  * This function is typically called only by the session leader, when
 461  * it wants to disassociate itself from its controlling tty.
 462  *
 463  * It performs the following functions:
 464  *      (1)  Sends a SIGHUP and SIGCONT to the foreground process group
 465  *      (2)  Clears the tty from being controlling the session
 466  *      (3)  Clears the controlling tty for all processes in the
 467  *              session group.
 468  *
 469  * The argument on_exit is set to 1 if called when a process is
 470  * exiting; it is 0 if called by the ioctl TIOCNOTTY.
 471  */
 472 void disassociate_ctty(int on_exit)
     /*  */
 473 {
 474         struct tty_struct *tty = current->tty;
 475         struct task_struct *p;
 476 
 477         if (tty) {
 478                 if (on_exit)
 479                         tty_vhangup(tty);
 480         } else {
 481                 if (current->tty_old_pgrp) {
 482                         kill_pg(current->tty_old_pgrp, SIGHUP, on_exit);
 483                         kill_pg(current->tty_old_pgrp, SIGCONT, on_exit);
 484                 }
 485                 return;
 486         }
 487         if (tty->pgrp > 0) {
 488                 kill_pg(tty->pgrp, SIGHUP, on_exit);
 489                 kill_pg(tty->pgrp, SIGCONT, on_exit);
 490         }
 491 
 492         current->tty_old_pgrp = 0;
 493         tty->session = 0;
 494         tty->pgrp = -1;
 495 
 496         for_each_task(p)
 497                 if (p->session == current->session)
 498                         p->tty = NULL;
 499 }
 500 
 501 /*
 502  * Sometimes we want to wait until a particular VT has been activated. We
 503  * do it in a very simple manner. Everybody waits on a single queue and
 504  * get woken up at once. Those that are satisfied go on with their business,
 505  * while those not ready go back to sleep. Seems overkill to add a wait
 506  * to each vt just for this - usually this does nothing!
 507  */
 508 static struct wait_queue *vt_activate_queue = NULL;
 509 
 510 /*
 511  * Sleeps until a vt is activated, or the task is interrupted. Returns
 512  * 0 if activation, -1 if interrupted.
 513  */
 514 int vt_waitactive(void)
     /*  */
 515 {
 516         interruptible_sleep_on(&vt_activate_queue);
 517         return (current->signal & ~current->blocked) ? -1 : 0;
 518 }
 519 
 520 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
 521 
 522 void reset_vc(unsigned int new_console)
     /*  */
 523 {
 524         vt_cons[new_console]->vc_mode = KD_TEXT;
 525         kbd_table[new_console].kbdmode = VC_XLATE;
 526         vt_cons[new_console]->vt_mode.mode = VT_AUTO;
 527         vt_cons[new_console]->vt_mode.waitv = 0;
 528         vt_cons[new_console]->vt_mode.relsig = 0;
 529         vt_cons[new_console]->vt_mode.acqsig = 0;
 530         vt_cons[new_console]->vt_mode.frsig = 0;
 531         vt_cons[new_console]->vt_pid = -1;
 532         vt_cons[new_console]->vt_newvt = -1;
 533         reset_palette (new_console) ;
 534 }
 535 
 536 /*
 537  * Performs the back end of a vt switch
 538  */
 539 void complete_change_console(unsigned int new_console)
     /*  */
 540 {
 541         unsigned char old_vc_mode;
 542 
 543         if ((new_console == fg_console) || (vt_dont_switch))
 544                 return;
 545         if (!vc_cons_allocated(new_console))
 546                 return;
 547         last_console = fg_console;
 548 
 549         /*
 550          * If we're switching, we could be going from KD_GRAPHICS to
 551          * KD_TEXT mode or vice versa, which means we need to blank or
 552          * unblank the screen later.
 553          */
 554         old_vc_mode = vt_cons[fg_console]->vc_mode;
 555         update_screen(new_console);
 556 
 557         /*
 558          * If this new console is under process control, send it a signal
 559          * telling it that it has acquired. Also check if it has died and
 560          * clean up (similar to logic employed in change_console())
 561          */
 562         if (vt_cons[new_console]->vt_mode.mode == VT_PROCESS)
 563         {
 564                 /*
 565                  * Send the signal as privileged - kill_proc() will
 566                  * tell us if the process has gone or something else
 567                  * is awry
 568                  */
 569                 if (kill_proc(vt_cons[new_console]->vt_pid,
 570                               vt_cons[new_console]->vt_mode.acqsig,
 571                               1) != 0)
 572                 {
 573                 /*
 574                  * The controlling process has died, so we revert back to
 575                  * normal operation. In this case, we'll also change back
 576                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 577                  * but it saves the agony when the X server dies and the screen
 578                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 579                  * this outside of VT_PROCESS but there is no single process
 580                  * to account for and tracking tty count may be undesirable.
 581                  */
 582                         reset_vc(new_console);
 583                 }
 584         }
 585 
 586         /*
 587          * We do this here because the controlling process above may have
 588          * gone, and so there is now a new vc_mode
 589          */
 590         if (old_vc_mode != vt_cons[new_console]->vc_mode)
 591         {
 592                 if (vt_cons[new_console]->vc_mode == KD_TEXT)
 593                         do_unblank_screen();
 594                 else
 595                         do_blank_screen(1);
 596         }
 597 
 598         /* Set the colour palette for this VT */
 599         if (vt_cons[new_console]->vc_mode == KD_TEXT)
 600                 set_palette() ;
 601         
 602         /*
 603          * Wake anyone waiting for their VT to activate
 604          */
 605         vt_wake_waitactive();
 606         return;
 607 }
 608 
 609 /*
 610  * Performs the front-end of a vt switch
 611  */
 612 void change_console(unsigned int new_console)
     /*  */
 613 {
 614         if ((new_console == fg_console) || (vt_dont_switch))
 615                 return;
 616         if (!vc_cons_allocated(new_console))
 617                 return;
 618 
 619         /*
 620          * If this vt is in process mode, then we need to handshake with
 621          * that process before switching. Essentially, we store where that
 622          * vt wants to switch to and wait for it to tell us when it's done
 623          * (via VT_RELDISP ioctl).
 624          *
 625          * We also check to see if the controlling process still exists.
 626          * If it doesn't, we reset this vt to auto mode and continue.
 627          * This is a cheap way to track process control. The worst thing
 628          * that can happen is: we send a signal to a process, it dies, and
 629          * the switch gets "lost" waiting for a response; hopefully, the
 630          * user will try again, we'll detect the process is gone (unless
 631          * the user waits just the right amount of time :-) and revert the
 632          * vt to auto control.
 633          */
 634         if (vt_cons[fg_console]->vt_mode.mode == VT_PROCESS)
 635         {
 636                 /*
 637                  * Send the signal as privileged - kill_proc() will
 638                  * tell us if the process has gone or something else
 639                  * is awry
 640                  */
 641                 if (kill_proc(vt_cons[fg_console]->vt_pid,
 642                               vt_cons[fg_console]->vt_mode.relsig,
 643                               1) == 0)
 644                 {
 645                         /*
 646                          * It worked. Mark the vt to switch to and
 647                          * return. The process needs to send us a
 648                          * VT_RELDISP ioctl to complete the switch.
 649                          */
 650                         vt_cons[fg_console]->vt_newvt = new_console;
 651                         return;
 652                 }
 653 
 654                 /*
 655                  * The controlling process has died, so we revert back to
 656                  * normal operation. In this case, we'll also change back
 657                  * to KD_TEXT mode. I'm not sure if this is strictly correct
 658                  * but it saves the agony when the X server dies and the screen
 659                  * remains blanked due to KD_GRAPHICS! It would be nice to do
 660                  * this outside of VT_PROCESS but there is no single process
 661                  * to account for and tracking tty count may be undesirable.
 662                  */
 663                 reset_vc(fg_console);
 664 
 665                 /*
 666                  * Fall through to normal (VT_AUTO) handling of the switch...
 667                  */
 668         }
 669 
 670         /*
 671          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
 672          */
 673         if (vt_cons[fg_console]->vc_mode == KD_GRAPHICS)
 674                 return;
 675 
 676         complete_change_console(new_console);
 677 }
 678 
 679 void wait_for_keypress(void)
     /*  */
 680 {
 681         sleep_on(&keypress_wait);
 682 }
 683 
 684 void stop_tty(struct tty_struct *tty)
     /*  */
 685 {
 686         if (tty->stopped)
 687                 return;
 688         tty->stopped = 1;
 689         if (tty->link && tty->link->packet) {
 690                 tty->ctrl_status &= ~TIOCPKT_START;
 691                 tty->ctrl_status |= TIOCPKT_STOP;
 692                 wake_up_interruptible(&tty->link->read_wait);
 693         }
 694         if (tty->driver.stop)
 695                 (tty->driver.stop)(tty);
 696 }
 697 
 698 void start_tty(struct tty_struct *tty)
     /*  */
 699 {
 700         if (!tty->stopped)
 701                 return;
 702         tty->stopped = 0;
 703         if (tty->link && tty->link->packet) {
 704                 tty->ctrl_status &= ~TIOCPKT_STOP;
 705                 tty->ctrl_status |= TIOCPKT_START;
 706                 wake_up_interruptible(&tty->link->read_wait);
 707         }
 708         if (tty->driver.start)
 709                 (tty->driver.start)(tty);
 710         if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
 711             tty->ldisc.write_wakeup)
 712                 (tty->ldisc.write_wakeup)(tty);
 713         wake_up_interruptible(&tty->write_wait);
 714 }
 715 
 716 static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
     /*  */
 717 {
 718         int i;
 719         struct tty_struct * tty;
 720 
 721         tty = (struct tty_struct *)file->private_data;
 722         if (tty_paranoia_check(tty, inode->i_rdev, "tty_read"))
 723                 return -EIO;
 724         if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
 725                 return -EIO;
 726 
 727         /* This check not only needs to be done before reading, but also
 728            whenever read_chan() gets woken up after sleeping, so I've
 729            moved it to there.  This should only be done for the N_TTY
 730            line discipline, anyway.  Same goes for write_chan(). -- jlc. */
 731 #if 0
 732         if ((inode->i_rdev != CONSOLE_DEV) && /* don't stop on /dev/console */
 733             (tty->pgrp > 0) &&
 734             (current->tty == tty) &&
 735             (tty->pgrp != current->pgrp))
 736                 if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
 737                         return -EIO;
 738                 else {
 739                         (void) kill_pg(current->pgrp, SIGTTIN, 1);
 740                         return -ERESTARTSYS;
 741                 }
 742 #endif
 743         if (tty->ldisc.read)
 744                 /* XXX casts are for what kernel-wide prototypes should be. */
 745                 i = (tty->ldisc.read)(tty,file,(unsigned char *)buf,(unsigned int)count);
 746         else
 747                 i = -EIO;
 748         if (i > 0)
 749                 inode->i_atime = CURRENT_TIME;
 750         return i;
 751 }
 752 
 753 static int tty_write(struct inode * inode, struct file * file, const char * buf, int count)
     /*  */
 754 {
 755         int i, is_console;
 756         struct tty_struct * tty;
 757 
 758         is_console = (inode->i_rdev == CONSOLE_DEV);
 759 
 760         if (is_console && redirect)
 761                 tty = redirect;
 762         else
 763                 tty = (struct tty_struct *)file->private_data;
 764         if (tty_paranoia_check(tty, inode->i_rdev, "tty_write"))
 765                 return -EIO;
 766         if (!tty || !tty->driver.write || (tty->flags & (1 << TTY_IO_ERROR)))
 767                 return -EIO;
 768 #if 0
 769         if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
 770             (current->tty == tty) && (tty->pgrp != current->pgrp)) {
 771                 if (is_orphaned_pgrp(current->pgrp))
 772                         return -EIO;
 773                 if (!is_ignored(SIGTTOU)) {
 774                         (void) kill_pg(current->pgrp, SIGTTOU, 1);
 775                         return -ERESTARTSYS;
 776                 }
 777         }
 778 #endif
 779         if (tty->ldisc.write)
 780                 /* XXX casts are for what kernel-wide prototypes should be. */
 781                 i = (tty->ldisc.write)(tty,file,(const unsigned char *)buf,(unsigned int)count);
 782         else
 783                 i = -EIO;
 784         if (i > 0)
 785                 inode->i_mtime = CURRENT_TIME;
 786         return i;
 787 }
 788 
 789 /*
 790  * This is so ripe with races that you should *really* not touch this
 791  * unless you know exactly what you are doing. All the changes have to be
 792  * made atomically, or there may be incorrect pointers all over the place.
 793  */
 794 static int init_dev(kdev_t device, struct tty_struct **ret_tty)
     /*  */
 795 {
 796         struct tty_struct *tty, **tty_loc, *o_tty, **o_tty_loc;
 797         struct termios *tp, **tp_loc, *o_tp, **o_tp_loc;
 798         struct termios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
 799         struct tty_driver *driver;      
 800         int retval;
 801         int idx;
 802 
 803         driver = get_tty_driver(device);
 804         if (!driver)
 805                 return -ENODEV;
 806 
 807         idx = MINOR(device) - driver->minor_start;
 808         tty = o_tty = NULL;
 809         tp = o_tp = NULL;
 810         ltp = o_ltp = NULL;
 811         o_tty_loc = NULL;
 812         o_tp_loc = o_ltp_loc = NULL;
 813 
 814         tty_loc = &driver->table[idx];
 815         tp_loc = &driver->termios[idx];
 816         ltp_loc = &driver->termios_locked[idx];
 817 
 818 repeat:
 819         retval = -EAGAIN;
 820         if (driver->type == TTY_DRIVER_TYPE_PTY &&
 821             driver->subtype == PTY_TYPE_MASTER &&
 822             *tty_loc && (*tty_loc)->count)
 823                 goto end_init;
 824         retval = -ENOMEM;
 825         if (!*tty_loc && !tty) {
 826                 if (!(tty = (struct tty_struct*) get_free_page(GFP_KERNEL)))
 827                         goto end_init;
 828                 initialize_tty_struct(tty);
 829                 tty->device = device;
 830                 tty->driver = *driver;
 831                 goto repeat;
 832         }
 833         if (!*tp_loc && !tp) {
 834                 tp = (struct termios *) kmalloc(sizeof(struct termios),
 835                                                 GFP_KERNEL);
 836                 if (!tp)
 837                         goto end_init;
 838                 *tp = driver->init_termios;
 839                 goto repeat;
 840         }
 841         if (!*ltp_loc && !ltp) {
 842                 ltp = (struct termios *) kmalloc(sizeof(struct termios),
 843                                                  GFP_KERNEL);
 844                 if (!ltp)
 845                         goto end_init;
 846                 memset(ltp, 0, sizeof(struct termios));
 847                 goto repeat;
 848         }
 849         if (driver->type == TTY_DRIVER_TYPE_PTY) {
 850                 o_tty_loc = &driver->other->table[idx];
 851                 o_tp_loc = &driver->other->termios[idx];
 852                 o_ltp_loc = &driver->other->termios_locked[idx];
 853 
 854                 if (!*o_tty_loc && !o_tty) {
 855                         kdev_t  o_device;
 856                         
 857                         o_tty = (struct tty_struct *)
 858                                 get_free_page(GFP_KERNEL);
 859                         if (!o_tty)
 860                                 goto end_init;
 861                         o_device = MKDEV(driver->other->major,
 862                                          driver->other->minor_start + idx);
 863                         initialize_tty_struct(o_tty);
 864                         o_tty->device = o_device;
 865                         o_tty->driver = *driver->other;
 866                         goto repeat;
 867                 }
 868                 if (!*o_tp_loc && !o_tp) {
 869                         o_tp = (struct termios *)
 870                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
 871                         if (!o_tp)
 872                                 goto end_init;
 873                         *o_tp = driver->other->init_termios;
 874                         goto repeat;
 875                 }
 876                 if (!*o_ltp_loc && !o_ltp) {
 877                         o_ltp = (struct termios *)
 878                                 kmalloc(sizeof(struct termios), GFP_KERNEL);
 879                         if (!o_ltp)
 880                                 goto end_init;
 881                         memset(o_ltp, 0, sizeof(struct termios));
 882                         goto repeat;
 883                 }
 884                 
 885         }
 886         /* Now we have allocated all the structures: update all the pointers.. */
 887         if (!*tp_loc) {
 888                 *tp_loc = tp;
 889                 tp = NULL;
 890         }
 891         if (!*ltp_loc) {
 892                 *ltp_loc = ltp;
 893                 ltp = NULL;
 894         }
 895         if (!*tty_loc) {
 896                 tty->termios = *tp_loc;
 897                 tty->termios_locked = *ltp_loc;
 898                 *tty_loc = tty;
 899                 (*driver->refcount)++;
 900                 (*tty_loc)->count++;
 901                 if (tty->ldisc.open) {
 902                         retval = (tty->ldisc.open)(tty);
 903                         if (retval < 0) {
 904                                 (*tty_loc)->count--;
 905                                 tty = NULL;
 906                                 goto end_init;
 907                         }
 908                 }
 909                 tty = NULL;
 910         } else {
 911                 if ((*tty_loc)->flags & (1 << TTY_CLOSING)) {
 912                         printk("Attempt to open closing tty %s.\n",
 913                                tty_name(*tty_loc));
 914                         printk("Ack!!!!  This should never happen!!\n");
 915                         return -EINVAL;
 916                 }
 917                 (*tty_loc)->count++;
 918         }
 919         if (driver->type == TTY_DRIVER_TYPE_PTY) {
 920                 if (!*o_tp_loc) {
 921                         *o_tp_loc = o_tp;
 922                         o_tp = NULL;
 923                 }
 924                 if (!*o_ltp_loc) {
 925                         *o_ltp_loc = o_ltp;
 926                         o_ltp = NULL;
 927                 }
 928                 if (!*o_tty_loc) {
 929                         o_tty->termios = *o_tp_loc;
 930                         o_tty->termios_locked = *o_ltp_loc;
 931                         *o_tty_loc = o_tty;
 932                         (*driver->other->refcount)++;
 933                         if (o_tty->ldisc.open) {
 934                                 retval = (o_tty->ldisc.open)(o_tty);
 935                                 if (retval < 0) {
 936                                         (*tty_loc)->count--;
 937                                         o_tty = NULL;
 938                                         goto end_init;
 939                                 }
 940                         }
 941                         o_tty = NULL;
 942                 }
 943                 (*tty_loc)->link = *o_tty_loc;
 944                 (*o_tty_loc)->link = *tty_loc;
 945                 if (driver->subtype == PTY_TYPE_MASTER)
 946                         (*o_tty_loc)->count++;
 947         }
 948         (*tty_loc)->driver = *driver;
 949         *ret_tty = *tty_loc;
 950         retval = 0;
 951 end_init:
 952         if (tty)
 953                 free_page((unsigned long) tty);
 954         if (o_tty)
 955                 free_page((unsigned long) o_tty);
 956         if (tp)
 957                 kfree_s(tp, sizeof(struct termios));
 958         if (o_tp)
 959                 kfree_s(o_tp, sizeof(struct termios));
 960         if (ltp)
 961                 kfree_s(ltp, sizeof(struct termios));
 962         if (o_ltp)
 963                 kfree_s(o_ltp, sizeof(struct termios));
 964         return retval;
 965 }
 966 
 967 /*
 968  * Even releasing the tty structures is a tricky business.. We have
 969  * to be very careful that the structures are all released at the
 970  * same time, as interrupts might otherwise get the wrong pointers.
 971  */
 972 static void release_dev(struct file * filp)
     /*  */
 973 {
 974         struct tty_struct *tty, *o_tty;
 975         struct termios *tp, *o_tp, *ltp, *o_ltp;
 976         struct task_struct **p;
 977         int     idx;
 978         
 979         tty = (struct tty_struct *)filp->private_data;
 980         if (tty_paranoia_check(tty, filp->f_inode->i_rdev, "release_dev"))
 981                 return;
 982 
 983         check_tty_count(tty, "release_dev");
 984 
 985         tty_fasync(filp->f_inode, filp, 0);
 986 
 987         tp = tty->termios;
 988         ltp = tty->termios_locked;
 989 
 990         idx = MINOR(tty->device) - tty->driver.minor_start;
 991 #ifdef TTY_PARANOIA_CHECK
 992         if (idx < 0 || idx >= tty->driver.num) {
 993                 printk("release_dev: bad idx when trying to free (%s)\n",
 994                        kdevname(tty->device));
 995                 return;
 996         }
 997         if (tty != tty->driver.table[idx]) {
 998                 printk("release_dev: driver.table[%d] not tty for (%s)\n",
 999                        idx, kdevname(tty->device));
1000                 return;
1001         }
1002         if (tp != tty->driver.termios[idx]) {
1003                 printk("release_dev: driver.termios[%d] not termios for ("
1004                        "%s)\n",
1005                        idx, kdevname(tty->device));
1006                 return;
1007         }
1008         if (ltp != tty->driver.termios_locked[idx]) {
1009                 printk("release_dev: driver.termios_locked[%d] not termios_locked for ("
1010                        "%s)\n",
1011                        idx, kdevname(tty->device));
1012                 return;
1013         }
1014 #endif
1015 
1016 #ifdef TTY_DEBUG_HANGUP
1017         printk("release_dev of %s (tty count=%d)...", tty_name(tty),
1018                tty->count);
1019 #endif
1020 
1021         o_tty = tty->link;
1022         o_tp = (o_tty) ? o_tty->termios : NULL;
1023         o_ltp = (o_tty) ? o_tty->termios_locked : NULL;
1024 
1025 #ifdef TTY_PARANOIA_CHECK
1026         if (tty->driver.other) {
1027                 if (o_tty != tty->driver.other->table[idx]) {
1028                         printk("release_dev: other->table[%d] not o_tty for ("
1029                                "%s)\n",
1030                                idx, kdevname(tty->device));
1031                         return;
1032                 }
1033                 if (o_tp != tty->driver.other->termios[idx]) {
1034                         printk("release_dev: other->termios[%d] not o_termios for ("
1035                                "%s)\n",
1036                                idx, kdevname(tty->device));
1037                         return;
1038                 }
1039                 if (o_ltp != tty->driver.other->termios_locked[idx]) {
1040                         printk("release_dev: other->termios_locked[%d] not o_termios_locked for ("
1041                                "%s)\n",
1042                                idx, kdevname(tty->device));
1043                         return;
1044                 }
1045 
1046                 if (o_tty->link != tty) {
1047                         printk("release_dev: bad pty pointers\n");
1048                         return;
1049                 }
1050         }
1051 #endif
1052         
1053         if (tty->driver.close)
1054                 tty->driver.close(tty, filp);
1055         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1056             tty->driver.subtype == PTY_TYPE_MASTER) {
1057                 if (--tty->link->count < 0) {
1058                         printk("release_dev: bad pty slave count (%d) for %s\n",
1059                                tty->count, tty_name(tty));
1060                         tty->link->count = 0;
1061                 }
1062         }
1063         if (--tty->count < 0) {
1064                 printk("release_dev: bad tty->count (%d) for %s\n",
1065                        tty->count, tty_name(tty));
1066                 tty->count = 0;
1067         }
1068         if (tty->count)
1069                 return;
1070 
1071         /*
1072          * We're committed; at this point, we must not block!
1073          */
1074         if (o_tty) {
1075                 if (o_tty->count)
1076                         return;
1077                 tty->driver.other->table[idx] = NULL;
1078                 tty->driver.other->termios[idx] = NULL;
1079                 kfree_s(o_tp, sizeof(struct termios));
1080         }
1081         
1082 #ifdef TTY_DEBUG_HANGUP
1083         printk("freeing tty structure...");
1084 #endif
1085         tty->flags |= (1 << TTY_CLOSING);
1086 
1087         /*
1088          * Make sure there aren't any processes that still think this
1089          * tty is their controlling tty.
1090          */
1091         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1092                 if (*p == 0)
1093                         continue;
1094                 if ((*p)->tty == tty)
1095                         (*p)->tty = NULL;
1096                 if (o_tty && (*p)->tty == o_tty)
1097                         (*p)->tty = NULL;
1098         }
1099 
1100         /*
1101          * Shutdown the current line discipline, and reset it to
1102          * N_TTY.
1103          */
1104         if (tty->ldisc.close)
1105                 (tty->ldisc.close)(tty);
1106         tty->ldisc = ldiscs[N_TTY];
1107         tty->termios->c_line = N_TTY;
1108         if (o_tty) {
1109                 if (o_tty->ldisc.close)
1110                         (o_tty->ldisc.close)(o_tty);
1111                 o_tty->ldisc = ldiscs[N_TTY];
1112         }
1113         
1114         tty->driver.table[idx] = NULL;
1115         if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS) {
1116                 tty->driver.termios[idx] = NULL;
1117                 kfree_s(tp, sizeof(struct termios));
1118         }
1119         if (tty == redirect || o_tty == redirect)
1120                 redirect = NULL;
1121         /*
1122          * Make sure that the tty's task queue isn't activated.  If it
1123          * is, take it out of the linked list.
1124          */
1125         cli();
1126         if (tty->flip.tqueue.sync) {
1127                 struct tq_struct *tq, *prev;
1128 
1129                 for (tq=tq_timer, prev=0; tq; prev=tq, tq=tq->next) {
1130                         if (tq == &tty->flip.tqueue) {
1131                                 if (prev)
1132                                         prev->next = tq->next;
1133                                 else
1134                                         tq_timer = tq->next;
1135                                 break;
1136                         }
1137                 }
1138         }
1139         sti();
1140         tty->magic = 0;
1141         (*tty->driver.refcount)--;
1142         free_page((unsigned long) tty);
1143         filp->private_data = 0;
1144         if (o_tty) {
1145                 o_tty->magic = 0;
1146                 (*o_tty->driver.refcount)--;
1147                 free_page((unsigned long) o_tty);
1148         }
1149 }
1150 
1151 /*
1152  * tty_open and tty_release keep up the tty count that contains the
1153  * number of opens done on a tty. We cannot use the inode-count, as
1154  * different inodes might point to the same tty.
1155  *
1156  * Open-counting is needed for pty masters, as well as for keeping
1157  * track of serial lines: DTR is dropped when the last close happens.
1158  * (This is not done solely through tty->count, now.  - Ted 1/27/92)
1159  *
1160  * The termios state of a pty is reset on first open so that
1161  * settings don't persist across reuse.
1162  */
1163 static int tty_open(struct inode * inode, struct file * filp)
     /*  */
1164 {
1165         struct tty_struct *tty;
1166         int minor;
1167         int noctty, retval;
1168         kdev_t device;
1169 
1170 retry_open:
1171         noctty = filp->f_flags & O_NOCTTY;
1172         device = inode->i_rdev;
1173         if (device == TTY_DEV) {
1174                 if (!current->tty)
1175                         return -ENXIO;
1176                 device = current->tty->device;
1177                 /* noctty = 1; */
1178         }
1179         if (device == CONSOLE_DEV) {
1180                 device = MKDEV(TTY_MAJOR, fg_console+1);
1181                 noctty = 1;
1182         }
1183         minor = MINOR(device);
1184         
1185         retval = init_dev(device, &tty);
1186         if (retval)
1187                 return retval;
1188         filp->private_data = tty;
1189         check_tty_count(tty, "tty_open");
1190         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1191             tty->driver.subtype == PTY_TYPE_MASTER)
1192                 noctty = 1;
1193 #ifdef TTY_DEBUG_HANGUP
1194         printk("opening %s...", tty_name(tty));
1195 #endif
1196         if (tty->driver.open)
1197                 retval = tty->driver.open(tty, filp);
1198         else
1199                 retval = -ENODEV;
1200 
1201         if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !suser())
1202                 retval = -EBUSY;
1203 
1204         if (retval) {
1205 #ifdef TTY_DEBUG_HANGUP
1206                 printk("error %d in opening %s...", retval, tty_name(tty));
1207 #endif
1208 
1209                 release_dev(filp);
1210                 if (retval != -ERESTARTSYS)
1211                         return retval;
1212                 if (current->signal & ~current->blocked)
1213                         return retval;
1214                 schedule();
1215                 /*
1216                  * Need to reset f_op in case a hangup happened.
1217                  */
1218                 filp->f_op = &tty_fops;
1219                 goto retry_open;
1220         }
1221         if (!noctty &&
1222             current->leader &&
1223             !current->tty &&
1224             tty->session == 0) {
1225                 current->tty = tty;
1226                 current->tty_old_pgrp = 0;
1227                 tty->session = current->session;
1228                 tty->pgrp = current->pgrp;
1229         }
1230         return 0;
1231 }
1232 
1233 /*
1234  * Note that releasing a pty master also releases the child, so
1235  * we have to make the redirection checks after that and on both
1236  * sides of a pty.
1237  */
1238 static void tty_release(struct inode * inode, struct file * filp)
     /*  */
1239 {
1240         release_dev(filp);
1241 }
1242 
1243 static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
     /*  */
1244 {
1245         struct tty_struct * tty;
1246 
1247         tty = (struct tty_struct *)filp->private_data;
1248         if (tty_paranoia_check(tty, inode->i_rdev, "tty_select"))
1249                 return 0;
1250 
1251         if (tty->ldisc.select)
1252                 return (tty->ldisc.select)(tty, inode, filp, sel_type, wait);
1253         return 0;
1254 }
1255 
1256 /*
1257  * fasync_helper() is used by some character device drivers (mainly mice)
1258  * to set up the fasync queue. It returns negative on error, 0 if it did
1259  * no changes and positive if it added/deleted the entry.
1260  */
1261 int fasync_helper(struct inode * inode, struct file * filp, int on, struct fasync_struct **fapp)
     /*  */
1262 {
1263         struct fasync_struct *fa, **fp;
1264         unsigned long flags;
1265 
1266         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
1267                 if (fa->fa_file == filp)
1268                         break;
1269         }
1270 
1271         if (on) {
1272                 if (fa)
1273                         return 0;
1274                 fa = (struct fasync_struct *)kmalloc(sizeof(struct fasync_struct), GFP_KERNEL);
1275                 if (!fa)
1276                         return -ENOMEM;
1277                 fa->magic = FASYNC_MAGIC;
1278                 fa->fa_file = filp;
1279                 save_flags(flags);
1280                 cli();
1281                 fa->fa_next = *fapp;
1282                 *fapp = fa;
1283                 restore_flags(flags);
1284                 return 1;
1285         }
1286         if (!fa)
1287                 return 0;
1288         save_flags(flags);
1289         cli();
1290         *fp = fa->fa_next;
1291         restore_flags(flags);
1292         kfree(fa);
1293         return 1;
1294 }
1295 
1296 static int tty_fasync(struct inode * inode, struct file * filp, int on)
     /*  */
1297 {
1298         struct tty_struct * tty;
1299         int retval;
1300 
1301         tty = (struct tty_struct *)filp->private_data;
1302         if (tty_paranoia_check(tty, inode->i_rdev, "tty_fasync"))
1303                 return 0;
1304         
1305         retval = fasync_helper(inode, filp, on, &tty->fasync);
1306         if (retval <= 0)
1307                 return retval;
1308 
1309         if (on) {
1310                 if (!tty->read_wait)
1311                         tty->minimum_to_wake = 1;
1312                 if (filp->f_owner == 0) {
1313                         if (tty->pgrp)
1314                                 filp->f_owner = -tty->pgrp;
1315                         else
1316                                 filp->f_owner = current->pid;
1317                 }
1318         } else {
1319                 if (!tty->fasync && !tty->read_wait)
1320                         tty->minimum_to_wake = N_TTY_BUF_SIZE;
1321         }
1322         return 0;
1323 }
1324 
1325 #if 0
1326 /*
1327  * XXX does anyone use this anymore?!?
1328  */
1329 static int do_get_ps_info(unsigned long arg)
     /*  */
1330 {
1331         struct tstruct {
1332                 int flag;
1333                 int present[NR_TASKS];
1334                 struct task_struct tasks[NR_TASKS];
1335         };
1336         struct tstruct *ts = (struct tstruct *)arg;
1337         struct task_struct **p;
1338         char *c, *d;
1339         int i, n = 0;
1340         
1341         i = verify_area(VERIFY_WRITE, (void *)arg, sizeof(struct tstruct));
1342         if (i)
1343                 return i;
1344         for (p = &FIRST_TASK ; p <= &LAST_TASK ; p++, n++)
1345                 if (*p)
1346                 {
1347                         c = (char *)(*p);
1348                         d = (char *)(ts->tasks+n);
1349                         for (i=0 ; i<sizeof(struct task_struct) ; i++)
1350                                 put_user(*c++, d++);
1351                         put_user(1, ts->present+n);
1352                 }
1353                 else    
1354                         put_user(0, ts->present+n);
1355         return(0);                      
1356 }
1357 #endif
1358 
1359 static int tty_ioctl(struct inode * inode, struct file * file,
     /*  */
1360                      unsigned int cmd, unsigned long arg)
1361 {
1362         int     retval;
1363         struct tty_struct * tty;
1364         struct tty_struct * real_tty;
1365         struct winsize tmp_ws;
1366         pid_t pgrp;
1367         unsigned char   ch;
1368         char    mbz = 0;
1369         
1370         tty = (struct tty_struct *)file->private_data;
1371         if (tty_paranoia_check(tty, inode->i_rdev, "tty_ioctl"))
1372                 return -EINVAL;
1373 
1374         if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
1375             tty->driver.subtype == PTY_TYPE_MASTER)
1376                 real_tty = tty->link;
1377         else
1378                 real_tty = tty;
1379 
1380         switch (cmd) {
1381                 case TIOCSTI:
1382                         if ((current->tty != tty) && !suser())
1383                                 return -EPERM;
1384                         retval = verify_area(VERIFY_READ, (void *) arg, 1);
1385                         if (retval)
1386                                 return retval;
1387                         ch = get_user((char *) arg);
1388                         tty->ldisc.receive_buf(tty, &ch, &mbz, 1);
1389                         return 0;
1390                 case TIOCGWINSZ:
1391                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1392                                              sizeof (struct winsize));
1393                         if (retval)
1394                                 return retval;
1395                         memcpy_tofs((struct winsize *) arg, &tty->winsize,
1396                                     sizeof (struct winsize));
1397                         return 0;
1398                 case TIOCSWINSZ:
1399                         retval = verify_area(VERIFY_READ, (void *) arg,
1400                                              sizeof (struct winsize));
1401                         if (retval)
1402                                 return retval;                  
1403                         memcpy_fromfs(&tmp_ws, (struct winsize *) arg,
1404                                       sizeof (struct winsize));
1405                         if (memcmp(&tmp_ws, &tty->winsize,
1406                                    sizeof(struct winsize))) {
1407                                 if (tty->pgrp > 0)
1408                                         kill_pg(tty->pgrp, SIGWINCH, 1);
1409                                 if ((real_tty->pgrp != tty->pgrp) &&
1410                                     (real_tty->pgrp > 0))
1411                                         kill_pg(real_tty->pgrp, SIGWINCH, 1);
1412                         }
1413                         tty->winsize = tmp_ws;
1414                         real_tty->winsize = tmp_ws;
1415                         return 0;
1416                 case TIOCCONS:
1417                         if (tty->driver.type == TTY_DRIVER_TYPE_CONSOLE) {
1418                                 if (!suser())
1419                                         return -EPERM;
1420                                 redirect = NULL;
1421                                 return 0;
1422                         }
1423                         if (redirect)
1424                                 return -EBUSY;
1425                         redirect = real_tty;
1426                         return 0;
1427                 case FIONBIO:
1428                         retval = verify_area(VERIFY_READ, (void *) arg, sizeof(int));
1429                         if (retval)
1430                                 return retval;
1431                         arg = get_user((unsigned int *) arg);
1432                         if (arg)
1433                                 file->f_flags |= O_NONBLOCK;
1434                         else
1435                                 file->f_flags &= ~O_NONBLOCK;
1436                         return 0;
1437                 case TIOCEXCL:
1438                         set_bit(TTY_EXCLUSIVE, &tty->flags);
1439                         return 0;
1440                 case TIOCNXCL:
1441                         clear_bit(TTY_EXCLUSIVE, &tty->flags);
1442                         return 0;
1443                 case TIOCNOTTY:
1444                         if (current->tty != tty)
1445                                 return -ENOTTY;
1446                         if (current->leader)
1447                                 disassociate_ctty(0);
1448                         current->tty = NULL;
1449                         return 0;
1450                 case TIOCSCTTY:
1451                         if (current->leader &&
1452                             (current->session == tty->session))
1453                                 return 0;
1454                         /*
1455                          * The process must be a session leader and
1456                          * not have a controlling tty already.
1457                          */
1458                         if (!current->leader || current->tty)
1459                                 return -EPERM;
1460                         if (tty->session > 0) {
1461                                 /*
1462                                  * This tty is already the controlling
1463                                  * tty for another session group!
1464                                  */
1465                                 if ((arg == 1) && suser()) {
1466                                         /*
1467                                          * Steal it away
1468                                          */
1469                                         struct task_struct *p;
1470 
1471                                         for_each_task(p)
1472                                                 if (p->tty == tty)
1473                                                         p->tty = NULL;
1474                                 } else
1475                                         return -EPERM;
1476                         }
1477                         current->tty = tty;
1478                         current->tty_old_pgrp = 0;
1479                         tty->session = current->session;
1480                         tty->pgrp = current->pgrp;
1481                         return 0;
1482                 case TIOCGPGRP:
1483                         /*
1484                          * (tty == real_tty) is a cheap way of
1485                          * testing if the tty is NOT a master pty.
1486                          */
1487                         if (tty == real_tty && current->tty != real_tty)
1488                                 return -ENOTTY;
1489                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1490                                              sizeof (pid_t));
1491                         if (retval)
1492                                 return retval;
1493                         put_user(real_tty->pgrp, (pid_t *) arg);
1494                         return 0;
1495                 case TIOCSPGRP:
1496                         retval = tty_check_change(real_tty);
1497                         if (retval)
1498                                 return retval;
1499                         if (!current->tty ||
1500                             (current->tty != real_tty) ||
1501                             (real_tty->session != current->session))
1502                                 return -ENOTTY;
1503                         pgrp = get_user((pid_t *) arg);
1504                         if (pgrp < 0)
1505                                 return -EINVAL;
1506                         if (session_of_pgrp(pgrp) != current->session)
1507                                 return -EPERM;
1508                         real_tty->pgrp = pgrp;
1509                         return 0;
1510                 case TIOCGETD:
1511                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1512                                              sizeof (int));
1513                         if (retval)
1514                                 return retval;
1515                         put_user(tty->ldisc.num, (int *) arg);
1516                         return 0;
1517                 case TIOCSETD:
1518                         retval = tty_check_change(tty);
1519                         if (retval)
1520                                 return retval;
1521                         arg = get_user((int *) arg);
1522                         return tty_set_ldisc(tty, arg);
1523                 case TIOCLINUX:
1524                         if (tty->driver.type != TTY_DRIVER_TYPE_CONSOLE)
1525                                 return -EINVAL;
1526                         if (current->tty != tty && !suser())
1527                                 return -EPERM;
1528                         retval = verify_area(VERIFY_READ, (void *) arg, 1);
1529                         if (retval)
1530                                 return retval;
1531                         switch (retval = get_user((char *)arg))
1532                         {
1533                                 case 0:
1534                                 case 8:
1535                                 case 9:
1536                                         printk("TIOCLINUX (0/8/9) ioctl is gone - use /dev/vcs\n");
1537                                         return -EINVAL;
1538 #if 0
1539                                 case 1:
1540                                         printk("Deprecated TIOCLINUX (1) ioctl\n");
1541                                         return do_get_ps_info(arg);
1542 #endif
1543                                 case 2:
1544                                         return set_selection(arg, tty);
1545                                 case 3:
1546                                         return paste_selection(tty);
1547                                 case 4:
1548                                         do_unblank_screen();
1549                                         return 0;
1550                                 case 5:
1551                                         return sel_loadlut(arg);
1552                                 case 6:
1553                         /*
1554                          * Make it possible to react to Shift+Mousebutton.
1555                          * Note that 'shift_state' is an undocumented
1556                          * kernel-internal variable; programs not closely
1557                          * related to the kernel should not use this.
1558                          */
1559                                         put_user(shift_state,(char *) arg);
1560                                         return 0;
1561                                 case 7:
1562                                         put_user(mouse_reporting(),(char *) arg);
1563                                         return 0;
1564                                 case 10:
1565                                         set_vesa_blanking(arg);
1566                                         return 0;
1567                                 case 11:        /* set kmsg redirect */
1568                                         if (!suser())
1569                                                 return -EPERM;
1570                                         retval = verify_area(VERIFY_READ,
1571                                                 (void *) arg+1, 1);
1572                                         if (retval)
1573                                                 return retval;
1574                                         kmsg_redirect = get_user((char *)arg+1);
1575                                         return 0;
1576                                 case 12:        /* get fg_console */
1577                                         return fg_console;
1578                                 default: 
1579                                         return -EINVAL;
1580                         }
1581 
1582                 case TIOCTTYGSTRUCT:
1583                         retval = verify_area(VERIFY_WRITE, (void *) arg,
1584                                                 sizeof(struct tty_struct));
1585                         if (retval)
1586                                 return retval;
1587                         memcpy_tofs((struct tty_struct *) arg,
1588                                     tty, sizeof(struct tty_struct));
1589                         return 0;
1590                 default:
1591                         if (tty->driver.ioctl) {
1592                                 retval = (tty->driver.ioctl)(tty, file,
1593                                                              cmd, arg);
1594                                 if (retval != -ENOIOCTLCMD)
1595                                         return retval;
1596                         }
1597                         if (tty->ldisc.ioctl) {
1598                                 retval = (tty->ldisc.ioctl)(tty, file,
1599                                                             cmd, arg);
1600                                 if (retval != -ENOIOCTLCMD)
1601                                         return retval;
1602                         }
1603                         return -EINVAL;
1604                 }
1605 }
1606 
1607 
1608 /*
1609  * This implements the "Secure Attention Key" ---  the idea is to
1610  * prevent trojan horses by killing all processes associated with this
1611  * tty when the user hits the "Secure Attention Key".  Required for
1612  * super-paranoid applications --- see the Orange Book for more details.
1613  * 
1614  * This code could be nicer; ideally it should send a HUP, wait a few
1615  * seconds, then send a INT, and then a KILL signal.  But you then
1616  * have to coordinate with the init process, since all processes associated
1617  * with the current tty must be dead before the new getty is allowed
1618  * to spawn.
1619  */
1620 void do_SAK( struct tty_struct *tty)
     /*  */
1621 {
1622 #ifdef TTY_SOFT_SAK
1623         tty_hangup(tty);
1624 #else
1625         struct task_struct **p;
1626         int session;
1627         int             i;
1628         struct file     *filp;
1629         
1630         if (!tty)
1631                 return;
1632         session  = tty->session;
1633         if (tty->ldisc.flush_buffer)
1634                 tty->ldisc.flush_buffer(tty);
1635         if (tty->driver.flush_buffer)
1636                 tty->driver.flush_buffer(tty);
1637         for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
1638                 if (!(*p))
1639                         continue;
1640                 if (((*p)->tty == tty) ||
1641                     ((session > 0) && ((*p)->session == session)))
1642                         send_sig(SIGKILL, *p, 1);
1643                 else {
1644                         for (i=0; i < NR_OPEN; i++) {
1645                                 filp = (*p)->files->fd[i];
1646                                 if (filp && (filp->f_op == &tty_fops) &&
1647                                     (filp->private_data == tty)) {
1648                                         send_sig(SIGKILL, *p, 1);
1649                                         break;
1650                                 }
1651                         }
1652                 }
1653         }
1654 #endif
1655 }
1656 
1657 /*
1658  * This routine is called out of the software interrupt to flush data
1659  * from the flip buffer to the line discipline.
1660  */
1661 static void flush_to_ldisc(void *private_)
     /*  */
1662 {
1663         struct tty_struct *tty = (struct tty_struct *) private_;
1664         unsigned char   *cp;
1665         char            *fp;
1666         int             count;
1667 
1668         if (tty->flip.buf_num) {
1669                 cp = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
1670                 fp = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
1671                 tty->flip.buf_num = 0;
1672 
1673                 cli();
1674                 tty->flip.char_buf_ptr = tty->flip.char_buf;
1675                 tty->flip.flag_buf_ptr = tty->flip.flag_buf;
1676         } else {
1677                 cp = tty->flip.char_buf;
1678                 fp = tty->flip.flag_buf;
1679                 tty->flip.buf_num = 1;
1680 
1681                 cli();
1682                 tty->flip.char_buf_ptr = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
1683                 tty->flip.flag_buf_ptr = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
1684         }
1685         count = tty->flip.count;
1686         tty->flip.count = 0;
1687         sti();
1688         
1689 #if 0
1690         if (count > tty->max_flip_cnt)
1691                 tty->max_flip_cnt = count;
1692 #endif
1693         tty->ldisc.receive_buf(tty, cp, fp, count);
1694 }
1695 
1696 /*
1697  * This subroutine initializes a tty structure.
1698  */
1699 static void initialize_tty_struct(struct tty_struct *tty)
     /*  */
1700 {
1701         memset(tty, 0, sizeof(struct tty_struct));
1702         tty->magic = TTY_MAGIC;
1703         tty->ldisc = ldiscs[N_TTY];
1704         tty->pgrp = -1;
1705         tty->flip.char_buf_ptr = tty->flip.char_buf;
1706         tty->flip.flag_buf_ptr = tty->flip.flag_buf;
1707         tty->flip.tqueue.routine = flush_to_ldisc;
1708         tty->flip.tqueue.data = tty;
1709 }
1710 
1711 /*
1712  * The default put_char routine if the driver did not define one.
1713  */
1714 void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
     /*  */
1715 {
1716         tty->driver.write(tty, 0, &ch, 1);
1717 }
1718 
1719 /*
1720  * Called by a tty driver to register itself.
1721  */
1722 int tty_register_driver(struct tty_driver *driver)
     /*  */
1723 {
1724         int error;
1725 
1726         if (driver->flags & TTY_DRIVER_INSTALLED)
1727                 return 0;
1728 
1729         error = register_chrdev(driver->major, driver->name, &tty_fops);
1730         if (error < 0)
1731                 return error;
1732         else if(driver->major == 0)
1733                 driver->major = error;
1734 
1735         if (!driver->put_char)
1736                 driver->put_char = tty_default_put_char;
1737         
1738         driver->prev = 0;
1739         driver->next = tty_drivers;
1740         if (tty_drivers) tty_drivers->prev = driver;
1741         tty_drivers = driver;
1742         return error;
1743 }
1744 
1745 /*
1746  * Called by a tty driver to unregister itself.
1747  */
1748 int tty_unregister_driver(struct tty_driver *driver)
     /*  */
1749 {
1750         int     retval;
1751         struct tty_driver *p;
1752         int     found = 0;
1753         const char *othername = NULL;
1754         
1755         if (*driver->refcount)
1756                 return -EBUSY;
1757 
1758         for (p = tty_drivers; p; p = p->next) {
1759                 if (p == driver)
1760                         found++;
1761                 else if (p->major == driver->major)
1762                         othername = p->name;
1763         }
1764 
1765         if (othername == NULL) {
1766                 retval = unregister_chrdev(driver->major, driver->name);
1767                 if (retval)
1768                         return retval;
1769         } else
1770                 register_chrdev(driver->major, othername, &tty_fops);
1771 
1772         if (driver->prev)
1773                 driver->prev->next = driver->next;
1774         else
1775                 tty_drivers = driver->next;
1776         
1777         if (driver->next)
1778                 driver->next->prev = driver->prev;
1779 
1780         return 0;
1781 }
1782 
1783 
1784 /*
1785  * Initialize the console device. This is called *early*, so
1786  * we can't necessarily depend on lots of kernel help here.
1787  * Just do some early initializations, and do the complex setup
1788  * later.
1789  */
1790 long console_init(long kmem_start, long kmem_end)
     /*  */
1791 {
1792         /* Setup the default TTY line discipline. */
1793         memset(ldiscs, 0, sizeof(ldiscs));
1794         (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
1795 
1796         /*
1797          * Set up the standard termios.  Individual tty drivers may 
1798          * deviate from this; this is used as a template.
1799          */
1800         memset(&tty_std_termios, 0, sizeof(struct termios));
1801         memcpy(tty_std_termios.c_cc, INIT_C_CC, NCCS);
1802         tty_std_termios.c_iflag = ICRNL | IXON;
1803         tty_std_termios.c_oflag = OPOST | ONLCR;
1804         tty_std_termios.c_cflag = B38400 | CS8 | CREAD;
1805         tty_std_termios.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
1806                 ECHOCTL | ECHOKE | IEXTEN;
1807 
1808         /*
1809          * set up the console device so that later boot sequences can 
1810          * inform about problems etc..
1811          */
1812         return con_init(kmem_start);
1813 }
1814 
1815 /*
1816  * Ok, now we can initialize the rest of the tty devices and can count
1817  * on memory allocations, interrupts etc..
1818  */
1819 int tty_init(void)
     /*  */
1820 {
1821         if (sizeof(struct tty_struct) > PAGE_SIZE)
1822                 panic("size of tty structure > PAGE_SIZE!");
1823         kbd_init();
1824         rs_init();
1825 #ifdef CONFIG_SCC
1826         scc_init();
1827 #endif
1828 #ifdef CONFIG_CYCLADES
1829         cy_init();
1830 #endif
1831 #ifdef CONFIG_STALLION
1832         stl_init();
1833 #endif
1834 #ifdef CONFIG_ISTALLION
1835         stli_init();
1836 #endif
1837         pty_init();
1838         vcs_init();
1839         if (register_chrdev(TTY_MAJOR,"tty",&tty_fops))
1840                 panic("unable to get major %d for tty device", TTY_MAJOR);
1841         if (register_chrdev(TTYAUX_MAJOR,"cua",&tty_fops))
1842                 panic("unable to get major %d for tty device", TTYAUX_MAJOR);
1843 
1844         return 0;
1845 }
/* */
root/drivers/char/tty_io.c

DEFINITIONS
