drivers/tty/pty.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *
   4  *  Added support for a Unix98-style ptmx device.
   5  *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
   6  *
   7  */
   8
   9 #include <linux/module.h>
  10
  11 #include <linux/errno.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/tty.h>
  14 #include <linux/tty_flip.h>
  15 #include <linux/fcntl.h>
  16 #include <linux/sched.h>
  17 #include <linux/string.h>
  18 #include <linux/major.h>
  19 #include <linux/mm.h>
  20 #include <linux/init.h>
  21 #include <linux/device.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/bitops.h>
  24 #include <linux/devpts_fs.h>
  25 #include <linux/slab.h>
  26 #include <linux/mutex.h>
  27
  28 #ifdef CONFIG_UNIX98_PTYS
  29 static struct tty_driver *ptm_driver;
  30 static struct tty_driver *pts_driver;
  31 static DEFINE_MUTEX(devpts_mutex);
  32 #endif
  33
  34 static void pty_close(struct tty_struct *tty, struct file *filp)
  35 {
  36         BUG_ON(!tty);
  37         if (tty->driver->subtype == PTY_TYPE_MASTER)
  38                 WARN_ON(tty->count > 1);
  39         else {
  40                 if (test_bit(TTY_IO_ERROR, &tty->flags))
  41                         return;
  42                 if (tty->count > 2)
  43                         return;
  44         }
  45         set_bit(TTY_IO_ERROR, &tty->flags);
  46         wake_up_interruptible(&tty->read_wait);
  47         wake_up_interruptible(&tty->write_wait);
  48         tty->packet = 0;
  49         /* Review - krefs on tty_link ?? */
  50         if (!tty->link)
  51                 return;
  52         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  53         wake_up_interruptible(&tty->link->read_wait);
  54         wake_up_interruptible(&tty->link->write_wait);
  55         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  56                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  57 #ifdef CONFIG_UNIX98_PTYS
  58                 if (tty->driver == ptm_driver) {
  59                         mutex_lock(&devpts_mutex);
  60                         if (tty->link->driver_data)
  61                                 devpts_pty_kill(tty->link->driver_data);
  62                         mutex_unlock(&devpts_mutex);
  63                 }
  64 #endif
  65                 tty_unlock(tty);
  66                 tty_vhangup(tty->link);
  67                 tty_lock(tty);
  68         }
  69 }
  70
  71 /*
  72  * The unthrottle routine is called by the line discipline to signal
  73  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  74  * flag is always set, to force the line discipline to always call the
  75  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  76  * characters in the queue.  This is necessary since each time this
  77  * happens, we need to wake up any sleeping processes that could be
  78  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  79  * for the pty buffer to be drained.
  80  */
  81 static void pty_unthrottle(struct tty_struct *tty)
  82 {
  83         tty_wakeup(tty->link);
  84         set_bit(TTY_THROTTLED, &tty->flags);
  85 }
  86
  87 /**
  88  *      pty_space       -       report space left for writing
  89  *      @to: tty we are writing into
  90  *
  91  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  92  *      allows a lot of overspill room for echo and other fun messes to
  93  *      be handled properly
  94  */
  95
  96 static int pty_space(struct tty_struct *to)
  97 {
  98         int n = 8192 - to->port->buf.memory_used;
  99         if (n < 0)
 100                 return 0;
 101         return n;
 102 }
 103
 104 /**
 105  *      pty_write               -       write to a pty
 106  *      @tty: the tty we write from
 107  *      @buf: kernel buffer of data
 108  *      @count: bytes to write
 109  *
 110  *      Our "hardware" write method. Data is coming from the ldisc which
 111  *      may be in a non sleeping state. We simply throw this at the other
 112  *      end of the link as if we were an IRQ handler receiving stuff for
 113  *      the other side of the pty/tty pair.
 114  */
 115
 116 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 117 {
 118         struct tty_struct *to = tty->link;
 119
 120         if (tty->stopped)
 121                 return 0;
 122
 123         if (c > 0) {
 124                 /* Stuff the data into the input queue of the other end */
 125                 c = tty_insert_flip_string(to->port, buf, c);
 126                 /* And shovel */
 127                 if (c) {
 128                         tty_flip_buffer_push(to->port);
 129                         tty_wakeup(tty);
 130                 }
 131         }
 132         return c;
 133 }
 134
 135 /**
 136  *      pty_write_room  -       write space
 137  *      @tty: tty we are writing from
 138  *
 139  *      Report how many bytes the ldisc can send into the queue for
 140  *      the other device.
 141  */
 142
 143 static int pty_write_room(struct tty_struct *tty)
 144 {
 145         if (tty->stopped)
 146                 return 0;
 147         return pty_space(tty->link);
 148 }
 149
 150 /**
 151  *      pty_chars_in_buffer     -       characters currently in our tx queue
 152  *      @tty: our tty
 153  *
 154  *      Report how much we have in the transmit queue. As everything is
 155  *      instantly at the other end this is easy to implement.
 156  */
 157
 158 static int pty_chars_in_buffer(struct tty_struct *tty)
 159 {
 160         return 0;
 161 }
 162
 163 /* Set the lock flag on a pty */
 164 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 165 {
 166         int val;
 167         if (get_user(val, arg))
 168                 return -EFAULT;
 169         if (val)
 170                 set_bit(TTY_PTY_LOCK, &tty->flags);
 171         else
 172                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 173         return 0;
 174 }
 175
 176 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
 177 {
 178         int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
 179         return put_user(locked, arg);
 180 }
 181
 182 /* Set the packet mode on a pty */
 183 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
 184 {
 185         unsigned long flags;
 186         int pktmode;
 187
 188         if (get_user(pktmode, arg))
 189                 return -EFAULT;
 190
 191         spin_lock_irqsave(&tty->ctrl_lock, flags);
 192         if (pktmode) {
 193                 if (!tty->packet) {
 194                         tty->packet = 1;
 195                         tty->link->ctrl_status = 0;
 196                 }
 197         } else
 198                 tty->packet = 0;
 199         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 200
 201         return 0;
 202 }
 203
 204 /* Get the packet mode of a pty */
 205 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
 206 {
 207         int pktmode = tty->packet;
 208         return put_user(pktmode, arg);
 209 }
 210
 211 /* Send a signal to the slave */
 212 static int pty_signal(struct tty_struct *tty, int sig)
 213 {
 214         unsigned long flags;
 215         struct pid *pgrp;
 216
 217         if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
 218                 return -EINVAL;
 219
 220         if (tty->link) {
 221                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 222                 pgrp = get_pid(tty->link->pgrp);
 223                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 224
 225                 kill_pgrp(pgrp, sig, 1);
 226                 put_pid(pgrp);
 227         }
 228         return 0;
 229 }
 230
 231 static void pty_flush_buffer(struct tty_struct *tty)
 232 {
 233         struct tty_struct *to = tty->link;
 234         unsigned long flags;
 235
 236         if (!to)
 237                 return;
 238         /* tty_buffer_flush(to); FIXME */
 239         if (to->packet) {
 240                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 241                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 242                 wake_up_interruptible(&to->read_wait);
 243                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 244         }
 245 }
 246
 247 static int pty_open(struct tty_struct *tty, struct file *filp)
 248 {
 249         if (!tty || !tty->link)
 250                 return -ENODEV;
 251
 252         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 253                 goto out;
 254         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 255                 goto out;
 256         if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
 257                 goto out;
 258
 259         clear_bit(TTY_IO_ERROR, &tty->flags);
 260         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 261         set_bit(TTY_THROTTLED, &tty->flags);
 262         return 0;
 263
 264 out:
 265         set_bit(TTY_IO_ERROR, &tty->flags);
 266         return -EIO;
 267 }
 268
 269 static void pty_set_termios(struct tty_struct *tty,
 270                                         struct ktermios *old_termios)
 271 {
 272         tty->termios.c_cflag &= ~(CSIZE | PARENB);
 273         tty->termios.c_cflag |= (CS8 | CREAD);
 274 }
 275
 276 /**
 277  *      pty_do_resize           -       resize event
 278  *      @tty: tty being resized
 279  *      @ws: window size being set.
 280  *
 281  *      Update the termios variables and send the necessary signals to
 282  *      peform a terminal resize correctly
 283  */
 284
 285 static int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 286 {
 287         struct pid *pgrp, *rpgrp;
 288         unsigned long flags;
 289         struct tty_struct *pty = tty->link;
 290
 291         /* For a PTY we need to lock the tty side */
 292         mutex_lock(&tty->termios_mutex);
 293         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 294                 goto done;
 295
 296         /* Get the PID values and reference them so we can
 297            avoid holding the tty ctrl lock while sending signals.
 298            We need to lock these individually however. */
 299
 300         spin_lock_irqsave(&tty->ctrl_lock, flags);
 301         pgrp = get_pid(tty->pgrp);
 302         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 303
 304         spin_lock_irqsave(&pty->ctrl_lock, flags);
 305         rpgrp = get_pid(pty->pgrp);
 306         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 307
 308         if (pgrp)
 309                 kill_pgrp(pgrp, SIGWINCH, 1);
 310         if (rpgrp != pgrp && rpgrp)
 311                 kill_pgrp(rpgrp, SIGWINCH, 1);
 312
 313         put_pid(pgrp);
 314         put_pid(rpgrp);
 315
 316         tty->winsize = *ws;
 317         pty->winsize = *ws;     /* Never used so will go away soon */
 318 done:
 319         mutex_unlock(&tty->termios_mutex);
 320         return 0;
 321 }
 322
 323 /**
 324  *      pty_common_install              -       set up the pty pair
 325  *      @driver: the pty driver
 326  *      @tty: the tty being instantiated
 327  *      @bool: legacy, true if this is BSD style
 328  *
 329  *      Perform the initial set up for the tty/pty pair. Called from the
 330  *      tty layer when the port is first opened.
 331  *
 332  *      Locking: the caller must hold the tty_mutex
 333  */
 334 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 335                 bool legacy)
 336 {
 337         struct tty_struct *o_tty;
 338         struct tty_port *ports[2];
 339         int idx = tty->index;
 340         int retval = -ENOMEM;
 341
 342         o_tty = alloc_tty_struct();
 343         if (!o_tty)
 344                 goto err;
 345         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 346         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 347         if (!ports[0] || !ports[1])
 348                 goto err_free_tty;
 349         if (!try_module_get(driver->other->owner)) {
 350                 /* This cannot in fact currently happen */
 351                 goto err_free_tty;
 352         }
 353         initialize_tty_struct(o_tty, driver->other, idx);
 354
 355         if (legacy) {
 356                 /* We always use new tty termios data so we can do this
 357                    the easy way .. */
 358                 retval = tty_init_termios(tty);
 359                 if (retval)
 360                         goto err_deinit_tty;
 361
 362                 retval = tty_init_termios(o_tty);
 363                 if (retval)
 364                         goto err_free_termios;
 365
 366                 driver->other->ttys[idx] = o_tty;
 367                 driver->ttys[idx] = tty;
 368         } else {
 369                 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
 370                 tty->termios = driver->init_termios;
 371                 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
 372                 o_tty->termios = driver->other->init_termios;
 373         }
 374
 375         /*
 376          * Everything allocated ... set up the o_tty structure.
 377          */
 378         tty_driver_kref_get(driver->other);
 379         if (driver->subtype == PTY_TYPE_MASTER)
 380                 o_tty->count++;
 381         /* Establish the links in both directions */
 382         tty->link   = o_tty;
 383         o_tty->link = tty;
 384         tty_port_init(ports[0]);
 385         tty_port_init(ports[1]);
 386         o_tty->port = ports[0];
 387         tty->port = ports[1];
 388         o_tty->port->itty = o_tty;
 389
 390         tty_driver_kref_get(driver);
 391         tty->count++;
 392         return 0;
 393 err_free_termios:
 394         if (legacy)
 395                 tty_free_termios(tty);
 396 err_deinit_tty:
 397         deinitialize_tty_struct(o_tty);
 398         module_put(o_tty->driver->owner);
 399 err_free_tty:
 400         kfree(ports[0]);
 401         kfree(ports[1]);
 402         free_tty_struct(o_tty);
 403 err:
 404         return retval;
 405 }
 406
 407 static void pty_cleanup(struct tty_struct *tty)
 408 {
 409         tty_port_put(tty->port);
 410 }
 411
 412 /* Traditional BSD devices */
 413 #ifdef CONFIG_LEGACY_PTYS
 414
 415 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 416 {
 417         return pty_common_install(driver, tty, true);
 418 }
 419
 420 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
 421 {
 422         struct tty_struct *pair = tty->link;
 423         driver->ttys[tty->index] = NULL;
 424         if (pair)
 425                 pair->driver->ttys[pair->index] = NULL;
 426 }
 427
 428 static int pty_bsd_ioctl(struct tty_struct *tty,
 429                          unsigned int cmd, unsigned long arg)
 430 {
 431         switch (cmd) {
 432         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 433                 return pty_set_lock(tty, (int __user *) arg);
 434         case TIOCGPTLCK: /* Get PT Lock status */
 435                 return pty_get_lock(tty, (int __user *)arg);
 436         case TIOCPKT: /* Set PT packet mode */
 437                 return pty_set_pktmode(tty, (int __user *)arg);
 438         case TIOCGPKT: /* Get PT packet mode */
 439                 return pty_get_pktmode(tty, (int __user *)arg);
 440         case TIOCSIG:    /* Send signal to other side of pty */
 441                 return pty_signal(tty, (int) arg);
 442         case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
 443                 return -EINVAL;
 444         }
 445         return -ENOIOCTLCMD;
 446 }
 447
 448 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 449 module_param(legacy_count, int, 0);
 450
 451 /*
 452  * The master side of a pty can do TIOCSPTLCK and thus
 453  * has pty_bsd_ioctl.
 454  */
 455 static const struct tty_operations master_pty_ops_bsd = {
 456         .install = pty_install,
 457         .open = pty_open,
 458         .close = pty_close,
 459         .write = pty_write,
 460         .write_room = pty_write_room,
 461         .flush_buffer = pty_flush_buffer,
 462         .chars_in_buffer = pty_chars_in_buffer,
 463         .unthrottle = pty_unthrottle,
 464         .set_termios = pty_set_termios,
 465         .ioctl = pty_bsd_ioctl,
 466         .cleanup = pty_cleanup,
 467         .resize = pty_resize,
 468         .remove = pty_remove
 469 };
 470
 471 static const struct tty_operations slave_pty_ops_bsd = {
 472         .install = pty_install,
 473         .open = pty_open,
 474         .close = pty_close,
 475         .write = pty_write,
 476         .write_room = pty_write_room,
 477         .flush_buffer = pty_flush_buffer,
 478         .chars_in_buffer = pty_chars_in_buffer,
 479         .unthrottle = pty_unthrottle,
 480         .set_termios = pty_set_termios,
 481         .cleanup = pty_cleanup,
 482         .resize = pty_resize,
 483         .remove = pty_remove
 484 };
 485
 486 static void __init legacy_pty_init(void)
 487 {
 488         struct tty_driver *pty_driver, *pty_slave_driver;
 489
 490         if (legacy_count <= 0)
 491                 return;
 492
 493         pty_driver = tty_alloc_driver(legacy_count,
 494                         TTY_DRIVER_RESET_TERMIOS |
 495                         TTY_DRIVER_REAL_RAW |
 496                         TTY_DRIVER_DYNAMIC_ALLOC);
 497         if (IS_ERR(pty_driver))
 498                 panic("Couldn't allocate pty driver");
 499
 500         pty_slave_driver = tty_alloc_driver(legacy_count,
 501                         TTY_DRIVER_RESET_TERMIOS |
 502                         TTY_DRIVER_REAL_RAW |
 503                         TTY_DRIVER_DYNAMIC_ALLOC);
 504         if (IS_ERR(pty_slave_driver))
 505                 panic("Couldn't allocate pty slave driver");
 506
 507         pty_driver->driver_name = "pty_master";
 508         pty_driver->name = "pty";
 509         pty_driver->major = PTY_MASTER_MAJOR;
 510         pty_driver->minor_start = 0;
 511         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 512         pty_driver->subtype = PTY_TYPE_MASTER;
 513         pty_driver->init_termios = tty_std_termios;
 514         pty_driver->init_termios.c_iflag = 0;
 515         pty_driver->init_termios.c_oflag = 0;
 516         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 517         pty_driver->init_termios.c_lflag = 0;
 518         pty_driver->init_termios.c_ispeed = 38400;
 519         pty_driver->init_termios.c_ospeed = 38400;
 520         pty_driver->other = pty_slave_driver;
 521         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 522
 523         pty_slave_driver->driver_name = "pty_slave";
 524         pty_slave_driver->name = "ttyp";
 525         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 526         pty_slave_driver->minor_start = 0;
 527         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 528         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 529         pty_slave_driver->init_termios = tty_std_termios;
 530         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 531         pty_slave_driver->init_termios.c_ispeed = 38400;
 532         pty_slave_driver->init_termios.c_ospeed = 38400;
 533         pty_slave_driver->other = pty_driver;
 534         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 535
 536         if (tty_register_driver(pty_driver))
 537                 panic("Couldn't register pty driver");
 538         if (tty_register_driver(pty_slave_driver))
 539                 panic("Couldn't register pty slave driver");
 540 }
 541 #else
 542 static inline void legacy_pty_init(void) { }
 543 #endif
 544
 545 /* Unix98 devices */
 546 #ifdef CONFIG_UNIX98_PTYS
 547
 548 static struct cdev ptmx_cdev;
 549
 550 static int pty_unix98_ioctl(struct tty_struct *tty,
 551                             unsigned int cmd, unsigned long arg)
 552 {
 553         switch (cmd) {
 554         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 555                 return pty_set_lock(tty, (int __user *)arg);
 556         case TIOCGPTLCK: /* Get PT Lock status */
 557                 return pty_get_lock(tty, (int __user *)arg);
 558         case TIOCPKT: /* Set PT packet mode */
 559                 return pty_set_pktmode(tty, (int __user *)arg);
 560         case TIOCGPKT: /* Get PT packet mode */
 561                 return pty_get_pktmode(tty, (int __user *)arg);
 562         case TIOCGPTN: /* Get PT Number */
 563                 return put_user(tty->index, (unsigned int __user *)arg);
 564         case TIOCSIG:    /* Send signal to other side of pty */
 565                 return pty_signal(tty, (int) arg);
 566         }
 567
 568         return -ENOIOCTLCMD;
 569 }
 570
 571 /**
 572  *      ptm_unix98_lookup       -       find a pty master
 573  *      @driver: ptm driver
 574  *      @idx: tty index
 575  *
 576  *      Look up a pty master device. Called under the tty_mutex for now.
 577  *      This provides our locking.
 578  */
 579
 580 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 581                 struct inode *ptm_inode, int idx)
 582 {
 583         /* Master must be open via /dev/ptmx */
 584         return ERR_PTR(-EIO);
 585 }
 586
 587 /**
 588  *      pts_unix98_lookup       -       find a pty slave
 589  *      @driver: pts driver
 590  *      @idx: tty index
 591  *
 592  *      Look up a pty master device. Called under the tty_mutex for now.
 593  *      This provides our locking for the tty pointer.
 594  */
 595
 596 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 597                 struct inode *pts_inode, int idx)
 598 {
 599         struct tty_struct *tty;
 600
 601         mutex_lock(&devpts_mutex);
 602         tty = devpts_get_priv(pts_inode);
 603         mutex_unlock(&devpts_mutex);
 604         /* Master must be open before slave */
 605         if (!tty)
 606                 return ERR_PTR(-EIO);
 607         return tty;
 608 }
 609
 610 /* We have no need to install and remove our tty objects as devpts does all
 611    the work for us */
 612
 613 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 614 {
 615         return pty_common_install(driver, tty, false);
 616 }
 617
 618 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 619 {
 620 }
 621
 622 /* this is called once with whichever end is closed last */
 623 static void pty_unix98_shutdown(struct tty_struct *tty)
 624 {
 625         devpts_kill_index(tty->driver_data, tty->index);
 626 }
 627
 628 static const struct tty_operations ptm_unix98_ops = {
 629         .lookup = ptm_unix98_lookup,
 630         .install = pty_unix98_install,
 631         .remove = pty_unix98_remove,
 632         .open = pty_open,
 633         .close = pty_close,
 634         .write = pty_write,
 635         .write_room = pty_write_room,
 636         .flush_buffer = pty_flush_buffer,
 637         .chars_in_buffer = pty_chars_in_buffer,
 638         .unthrottle = pty_unthrottle,
 639         .set_termios = pty_set_termios,
 640         .ioctl = pty_unix98_ioctl,
 641         .resize = pty_resize,
 642         .shutdown = pty_unix98_shutdown,
 643         .cleanup = pty_cleanup
 644 };
 645
 646 static const struct tty_operations pty_unix98_ops = {
 647         .lookup = pts_unix98_lookup,
 648         .install = pty_unix98_install,
 649         .remove = pty_unix98_remove,
 650         .open = pty_open,
 651         .close = pty_close,
 652         .write = pty_write,
 653         .write_room = pty_write_room,
 654         .flush_buffer = pty_flush_buffer,
 655         .chars_in_buffer = pty_chars_in_buffer,
 656         .unthrottle = pty_unthrottle,
 657         .set_termios = pty_set_termios,
 658         .shutdown = pty_unix98_shutdown,
 659         .cleanup = pty_cleanup,
 660 };
 661
 662 /**
 663  *      ptmx_open               -       open a unix 98 pty master
 664  *      @inode: inode of device file
 665  *      @filp: file pointer to tty
 666  *
 667  *      Allocate a unix98 pty master device from the ptmx driver.
 668  *
 669  *      Locking: tty_mutex protects the init_dev work. tty->count should
 670  *              protect the rest.
 671  *              allocated_ptys_lock handles the list of free pty numbers
 672  */
 673
 674 static int ptmx_open(struct inode *inode, struct file *filp)
 675 {
 676         struct tty_struct *tty;
 677         struct inode *slave_inode;
 678         int retval;
 679         int index;
 680
 681         nonseekable_open(inode, filp);
 682
 683         /* We refuse fsnotify events on ptmx, since it's a shared resource */
 684         filp->f_mode |= FMODE_NONOTIFY;
 685
 686         retval = tty_alloc_file(filp);
 687         if (retval)
 688                 return retval;
 689
 690         /* find a device that is not in use. */
 691         mutex_lock(&devpts_mutex);
 692         index = devpts_new_index(inode);
 693         if (index < 0) {
 694                 retval = index;
 695                 mutex_unlock(&devpts_mutex);
 696                 goto err_file;
 697         }
 698
 699         mutex_unlock(&devpts_mutex);
 700
 701         mutex_lock(&tty_mutex);
 702         tty = tty_init_dev(ptm_driver, index);
 703
 704         if (IS_ERR(tty)) {
 705                 retval = PTR_ERR(tty);
 706                 goto out;
 707         }
 708
 709         /* The tty returned here is locked so we can safely
 710            drop the mutex */
 711         mutex_unlock(&tty_mutex);
 712
 713         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 714         tty->driver_data = inode;
 715
 716         tty_add_file(tty, filp);
 717
 718         slave_inode = devpts_pty_new(inode,
 719                         MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
 720                         tty->link);
 721         if (IS_ERR(slave_inode)) {
 722                 retval = PTR_ERR(slave_inode);
 723                 goto err_release;
 724         }
 725         tty->link->driver_data = slave_inode;
 726
 727         retval = ptm_driver->ops->open(tty, filp);
 728         if (retval)
 729                 goto err_release;
 730
 731         tty_unlock(tty);
 732         return 0;
 733 err_release:
 734         tty_unlock(tty);
 735         tty_release(inode, filp);
 736         return retval;
 737 out:
 738         mutex_unlock(&tty_mutex);
 739         devpts_kill_index(inode, index);
 740 err_file:
 741         tty_free_file(filp);
 742         return retval;
 743 }
 744
 745 static struct file_operations ptmx_fops;
 746
 747 static void __init unix98_pty_init(void)
 748 {
 749         ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 750                         TTY_DRIVER_RESET_TERMIOS |
 751                         TTY_DRIVER_REAL_RAW |
 752                         TTY_DRIVER_DYNAMIC_DEV |
 753                         TTY_DRIVER_DEVPTS_MEM |
 754                         TTY_DRIVER_DYNAMIC_ALLOC);
 755         if (IS_ERR(ptm_driver))
 756                 panic("Couldn't allocate Unix98 ptm driver");
 757         pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 758                         TTY_DRIVER_RESET_TERMIOS |
 759                         TTY_DRIVER_REAL_RAW |
 760                         TTY_DRIVER_DYNAMIC_DEV |
 761                         TTY_DRIVER_DEVPTS_MEM |
 762                         TTY_DRIVER_DYNAMIC_ALLOC);
 763         if (IS_ERR(pts_driver))
 764                 panic("Couldn't allocate Unix98 pts driver");
 765
 766         ptm_driver->driver_name = "pty_master";
 767         ptm_driver->name = "ptm";
 768         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 769         ptm_driver->minor_start = 0;
 770         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 771         ptm_driver->subtype = PTY_TYPE_MASTER;
 772         ptm_driver->init_termios = tty_std_termios;
 773         ptm_driver->init_termios.c_iflag = 0;
 774         ptm_driver->init_termios.c_oflag = 0;
 775         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 776         ptm_driver->init_termios.c_lflag = 0;
 777         ptm_driver->init_termios.c_ispeed = 38400;
 778         ptm_driver->init_termios.c_ospeed = 38400;
 779         ptm_driver->other = pts_driver;
 780         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 781
 782         pts_driver->driver_name = "pty_slave";
 783         pts_driver->name = "pts";
 784         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 785         pts_driver->minor_start = 0;
 786         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 787         pts_driver->subtype = PTY_TYPE_SLAVE;
 788         pts_driver->init_termios = tty_std_termios;
 789         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 790         pts_driver->init_termios.c_ispeed = 38400;
 791         pts_driver->init_termios.c_ospeed = 38400;
 792         pts_driver->other = ptm_driver;
 793         tty_set_operations(pts_driver, &pty_unix98_ops);
 794
 795         if (tty_register_driver(ptm_driver))
 796                 panic("Couldn't register Unix98 ptm driver");
 797         if (tty_register_driver(pts_driver))
 798                 panic("Couldn't register Unix98 pts driver");
 799
 800         /* Now create the /dev/ptmx special device */
 801         tty_default_fops(&ptmx_fops);
 802         ptmx_fops.open = ptmx_open;
 803
 804         cdev_init(&ptmx_cdev, &ptmx_fops);
 805         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 806             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 807                 panic("Couldn't register /dev/ptmx driver");
 808         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 809 }
 810
 811 #else
 812 static inline void unix98_pty_init(void) { }
 813 #endif
 814
 815 static int __init pty_init(void)
 816 {
 817         legacy_pty_init();
 818         unix98_pty_init();
 819         return 0;
 820 }
 821 module_init(pty_init);