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 (tty->link) {
 218                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 219                 pgrp = get_pid(tty->link->pgrp);
 220                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 221
 222                 kill_pgrp(pgrp, sig, 1);
 223                 put_pid(pgrp);
 224         }
 225         return 0;
 226 }
 227
 228 static void pty_flush_buffer(struct tty_struct *tty)
 229 {
 230         struct tty_struct *to = tty->link;
 231         unsigned long flags;
 232
 233         if (!to)
 234                 return;
 235         /* tty_buffer_flush(to); FIXME */
 236         if (to->packet) {
 237                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 238                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 239                 wake_up_interruptible(&to->read_wait);
 240                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 241         }
 242 }
 243
 244 static int pty_open(struct tty_struct *tty, struct file *filp)
 245 {
 246         if (!tty || !tty->link)
 247                 return -ENODEV;
 248
 249         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 250                 goto out;
 251         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 252                 goto out;
 253         if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
 254                 goto out;
 255
 256         clear_bit(TTY_IO_ERROR, &tty->flags);
 257         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 258         set_bit(TTY_THROTTLED, &tty->flags);
 259         return 0;
 260
 261 out:
 262         set_bit(TTY_IO_ERROR, &tty->flags);
 263         return -EIO;
 264 }
 265
 266 static void pty_set_termios(struct tty_struct *tty,
 267                                         struct ktermios *old_termios)
 268 {
 269         tty->termios.c_cflag &= ~(CSIZE | PARENB);
 270         tty->termios.c_cflag |= (CS8 | CREAD);
 271 }
 272
 273 /**
 274  *      pty_do_resize           -       resize event
 275  *      @tty: tty being resized
 276  *      @ws: window size being set.
 277  *
 278  *      Update the termios variables and send the necessary signals to
 279  *      peform a terminal resize correctly
 280  */
 281
 282 static int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 283 {
 284         struct pid *pgrp, *rpgrp;
 285         unsigned long flags;
 286         struct tty_struct *pty = tty->link;
 287
 288         /* For a PTY we need to lock the tty side */
 289         mutex_lock(&tty->termios_mutex);
 290         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 291                 goto done;
 292
 293         /* Get the PID values and reference them so we can
 294            avoid holding the tty ctrl lock while sending signals.
 295            We need to lock these individually however. */
 296
 297         spin_lock_irqsave(&tty->ctrl_lock, flags);
 298         pgrp = get_pid(tty->pgrp);
 299         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 300
 301         spin_lock_irqsave(&pty->ctrl_lock, flags);
 302         rpgrp = get_pid(pty->pgrp);
 303         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 304
 305         if (pgrp)
 306                 kill_pgrp(pgrp, SIGWINCH, 1);
 307         if (rpgrp != pgrp && rpgrp)
 308                 kill_pgrp(rpgrp, SIGWINCH, 1);
 309
 310         put_pid(pgrp);
 311         put_pid(rpgrp);
 312
 313         tty->winsize = *ws;
 314         pty->winsize = *ws;     /* Never used so will go away soon */
 315 done:
 316         mutex_unlock(&tty->termios_mutex);
 317         return 0;
 318 }
 319
 320 /**
 321  *      pty_common_install              -       set up the pty pair
 322  *      @driver: the pty driver
 323  *      @tty: the tty being instantiated
 324  *      @bool: legacy, true if this is BSD style
 325  *
 326  *      Perform the initial set up for the tty/pty pair. Called from the
 327  *      tty layer when the port is first opened.
 328  *
 329  *      Locking: the caller must hold the tty_mutex
 330  */
 331 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 332                 bool legacy)
 333 {
 334         struct tty_struct *o_tty;
 335         struct tty_port *ports[2];
 336         int idx = tty->index;
 337         int retval = -ENOMEM;
 338
 339         o_tty = alloc_tty_struct();
 340         if (!o_tty)
 341                 goto err;
 342         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 343         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 344         if (!ports[0] || !ports[1])
 345                 goto err_free_tty;
 346         if (!try_module_get(driver->other->owner)) {
 347                 /* This cannot in fact currently happen */
 348                 goto err_free_tty;
 349         }
 350         initialize_tty_struct(o_tty, driver->other, idx);
 351
 352         if (legacy) {
 353                 /* We always use new tty termios data so we can do this
 354                    the easy way .. */
 355                 retval = tty_init_termios(tty);
 356                 if (retval)
 357                         goto err_deinit_tty;
 358
 359                 retval = tty_init_termios(o_tty);
 360                 if (retval)
 361                         goto err_free_termios;
 362
 363                 driver->other->ttys[idx] = o_tty;
 364                 driver->ttys[idx] = tty;
 365         } else {
 366                 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
 367                 tty->termios = driver->init_termios;
 368                 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
 369                 o_tty->termios = driver->other->init_termios;
 370         }
 371
 372         /*
 373          * Everything allocated ... set up the o_tty structure.
 374          */
 375         tty_driver_kref_get(driver->other);
 376         if (driver->subtype == PTY_TYPE_MASTER)
 377                 o_tty->count++;
 378         /* Establish the links in both directions */
 379         tty->link   = o_tty;
 380         o_tty->link = tty;
 381         tty_port_init(ports[0]);
 382         tty_port_init(ports[1]);
 383         o_tty->port = ports[0];
 384         tty->port = ports[1];
 385         o_tty->port->itty = o_tty;
 386
 387         tty_driver_kref_get(driver);
 388         tty->count++;
 389         return 0;
 390 err_free_termios:
 391         if (legacy)
 392                 tty_free_termios(tty);
 393 err_deinit_tty:
 394         deinitialize_tty_struct(o_tty);
 395         module_put(o_tty->driver->owner);
 396 err_free_tty:
 397         kfree(ports[0]);
 398         kfree(ports[1]);
 399         free_tty_struct(o_tty);
 400 err:
 401         return retval;
 402 }
 403
 404 static void pty_cleanup(struct tty_struct *tty)
 405 {
 406         tty_port_put(tty->port);
 407 }
 408
 409 /* Traditional BSD devices */
 410 #ifdef CONFIG_LEGACY_PTYS
 411
 412 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 413 {
 414         return pty_common_install(driver, tty, true);
 415 }
 416
 417 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
 418 {
 419         struct tty_struct *pair = tty->link;
 420         driver->ttys[tty->index] = NULL;
 421         if (pair)
 422                 pair->driver->ttys[pair->index] = NULL;
 423 }
 424
 425 static int pty_bsd_ioctl(struct tty_struct *tty,
 426                          unsigned int cmd, unsigned long arg)
 427 {
 428         switch (cmd) {
 429         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 430                 return pty_set_lock(tty, (int __user *) arg);
 431         case TIOCGPTLCK: /* Get PT Lock status */
 432                 return pty_get_lock(tty, (int __user *)arg);
 433         case TIOCPKT: /* Set PT packet mode */
 434                 return pty_set_pktmode(tty, (int __user *)arg);
 435         case TIOCGPKT: /* Get PT packet mode */
 436                 return pty_get_pktmode(tty, (int __user *)arg);
 437         case TIOCSIG:    /* Send signal to other side of pty */
 438                 return pty_signal(tty, (int) arg);
 439         case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
 440                 return -EINVAL;
 441         }
 442         return -ENOIOCTLCMD;
 443 }
 444
 445 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 446 module_param(legacy_count, int, 0);
 447
 448 /*
 449  * The master side of a pty can do TIOCSPTLCK and thus
 450  * has pty_bsd_ioctl.
 451  */
 452 static const struct tty_operations master_pty_ops_bsd = {
 453         .install = pty_install,
 454         .open = pty_open,
 455         .close = pty_close,
 456         .write = pty_write,
 457         .write_room = pty_write_room,
 458         .flush_buffer = pty_flush_buffer,
 459         .chars_in_buffer = pty_chars_in_buffer,
 460         .unthrottle = pty_unthrottle,
 461         .set_termios = pty_set_termios,
 462         .ioctl = pty_bsd_ioctl,
 463         .cleanup = pty_cleanup,
 464         .resize = pty_resize,
 465         .remove = pty_remove
 466 };
 467
 468 static const struct tty_operations slave_pty_ops_bsd = {
 469         .install = pty_install,
 470         .open = pty_open,
 471         .close = pty_close,
 472         .write = pty_write,
 473         .write_room = pty_write_room,
 474         .flush_buffer = pty_flush_buffer,
 475         .chars_in_buffer = pty_chars_in_buffer,
 476         .unthrottle = pty_unthrottle,
 477         .set_termios = pty_set_termios,
 478         .cleanup = pty_cleanup,
 479         .resize = pty_resize,
 480         .remove = pty_remove
 481 };
 482
 483 static void __init legacy_pty_init(void)
 484 {
 485         struct tty_driver *pty_driver, *pty_slave_driver;
 486
 487         if (legacy_count <= 0)
 488                 return;
 489
 490         pty_driver = tty_alloc_driver(legacy_count,
 491                         TTY_DRIVER_RESET_TERMIOS |
 492                         TTY_DRIVER_REAL_RAW |
 493                         TTY_DRIVER_DYNAMIC_ALLOC);
 494         if (IS_ERR(pty_driver))
 495                 panic("Couldn't allocate pty driver");
 496
 497         pty_slave_driver = tty_alloc_driver(legacy_count,
 498                         TTY_DRIVER_RESET_TERMIOS |
 499                         TTY_DRIVER_REAL_RAW |
 500                         TTY_DRIVER_DYNAMIC_ALLOC);
 501         if (IS_ERR(pty_slave_driver))
 502                 panic("Couldn't allocate pty slave driver");
 503
 504         pty_driver->driver_name = "pty_master";
 505         pty_driver->name = "pty";
 506         pty_driver->major = PTY_MASTER_MAJOR;
 507         pty_driver->minor_start = 0;
 508         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 509         pty_driver->subtype = PTY_TYPE_MASTER;
 510         pty_driver->init_termios = tty_std_termios;
 511         pty_driver->init_termios.c_iflag = 0;
 512         pty_driver->init_termios.c_oflag = 0;
 513         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 514         pty_driver->init_termios.c_lflag = 0;
 515         pty_driver->init_termios.c_ispeed = 38400;
 516         pty_driver->init_termios.c_ospeed = 38400;
 517         pty_driver->other = pty_slave_driver;
 518         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 519
 520         pty_slave_driver->driver_name = "pty_slave";
 521         pty_slave_driver->name = "ttyp";
 522         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 523         pty_slave_driver->minor_start = 0;
 524         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 525         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 526         pty_slave_driver->init_termios = tty_std_termios;
 527         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 528         pty_slave_driver->init_termios.c_ispeed = 38400;
 529         pty_slave_driver->init_termios.c_ospeed = 38400;
 530         pty_slave_driver->other = pty_driver;
 531         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 532
 533         if (tty_register_driver(pty_driver))
 534                 panic("Couldn't register pty driver");
 535         if (tty_register_driver(pty_slave_driver))
 536                 panic("Couldn't register pty slave driver");
 537 }
 538 #else
 539 static inline void legacy_pty_init(void) { }
 540 #endif
 541
 542 /* Unix98 devices */
 543 #ifdef CONFIG_UNIX98_PTYS
 544
 545 static struct cdev ptmx_cdev;
 546
 547 static int pty_unix98_ioctl(struct tty_struct *tty,
 548                             unsigned int cmd, unsigned long arg)
 549 {
 550         switch (cmd) {
 551         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 552                 return pty_set_lock(tty, (int __user *)arg);
 553         case TIOCGPTLCK: /* Get PT Lock status */
 554                 return pty_get_lock(tty, (int __user *)arg);
 555         case TIOCPKT: /* Set PT packet mode */
 556                 return pty_set_pktmode(tty, (int __user *)arg);
 557         case TIOCGPKT: /* Get PT packet mode */
 558                 return pty_get_pktmode(tty, (int __user *)arg);
 559         case TIOCGPTN: /* Get PT Number */
 560                 return put_user(tty->index, (unsigned int __user *)arg);
 561         case TIOCSIG:    /* Send signal to other side of pty */
 562                 return pty_signal(tty, (int) arg);
 563         }
 564
 565         return -ENOIOCTLCMD;
 566 }
 567
 568 /**
 569  *      ptm_unix98_lookup       -       find a pty master
 570  *      @driver: ptm driver
 571  *      @idx: tty index
 572  *
 573  *      Look up a pty master device. Called under the tty_mutex for now.
 574  *      This provides our locking.
 575  */
 576
 577 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 578                 struct inode *ptm_inode, int idx)
 579 {
 580         /* Master must be open via /dev/ptmx */
 581         return ERR_PTR(-EIO);
 582 }
 583
 584 /**
 585  *      pts_unix98_lookup       -       find a pty slave
 586  *      @driver: pts driver
 587  *      @idx: tty index
 588  *
 589  *      Look up a pty master device. Called under the tty_mutex for now.
 590  *      This provides our locking for the tty pointer.
 591  */
 592
 593 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 594                 struct inode *pts_inode, int idx)
 595 {
 596         struct tty_struct *tty;
 597
 598         mutex_lock(&devpts_mutex);
 599         tty = devpts_get_priv(pts_inode);
 600         mutex_unlock(&devpts_mutex);
 601         /* Master must be open before slave */
 602         if (!tty)
 603                 return ERR_PTR(-EIO);
 604         return tty;
 605 }
 606
 607 /* We have no need to install and remove our tty objects as devpts does all
 608    the work for us */
 609
 610 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 611 {
 612         return pty_common_install(driver, tty, false);
 613 }
 614
 615 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 616 {
 617 }
 618
 619 /* this is called once with whichever end is closed last */
 620 static void pty_unix98_shutdown(struct tty_struct *tty)
 621 {
 622         devpts_kill_index(tty->driver_data, tty->index);
 623 }
 624
 625 static const struct tty_operations ptm_unix98_ops = {
 626         .lookup = ptm_unix98_lookup,
 627         .install = pty_unix98_install,
 628         .remove = pty_unix98_remove,
 629         .open = pty_open,
 630         .close = pty_close,
 631         .write = pty_write,
 632         .write_room = pty_write_room,
 633         .flush_buffer = pty_flush_buffer,
 634         .chars_in_buffer = pty_chars_in_buffer,
 635         .unthrottle = pty_unthrottle,
 636         .set_termios = pty_set_termios,
 637         .ioctl = pty_unix98_ioctl,
 638         .resize = pty_resize,
 639         .shutdown = pty_unix98_shutdown,
 640         .cleanup = pty_cleanup
 641 };
 642
 643 static const struct tty_operations pty_unix98_ops = {
 644         .lookup = pts_unix98_lookup,
 645         .install = pty_unix98_install,
 646         .remove = pty_unix98_remove,
 647         .open = pty_open,
 648         .close = pty_close,
 649         .write = pty_write,
 650         .write_room = pty_write_room,
 651         .flush_buffer = pty_flush_buffer,
 652         .chars_in_buffer = pty_chars_in_buffer,
 653         .unthrottle = pty_unthrottle,
 654         .set_termios = pty_set_termios,
 655         .shutdown = pty_unix98_shutdown,
 656         .cleanup = pty_cleanup,
 657 };
 658
 659 /**
 660  *      ptmx_open               -       open a unix 98 pty master
 661  *      @inode: inode of device file
 662  *      @filp: file pointer to tty
 663  *
 664  *      Allocate a unix98 pty master device from the ptmx driver.
 665  *
 666  *      Locking: tty_mutex protects the init_dev work. tty->count should
 667  *              protect the rest.
 668  *              allocated_ptys_lock handles the list of free pty numbers
 669  */
 670
 671 static int ptmx_open(struct inode *inode, struct file *filp)
 672 {
 673         struct tty_struct *tty;
 674         struct inode *slave_inode;
 675         int retval;
 676         int index;
 677
 678         nonseekable_open(inode, filp);
 679
 680         /* We refuse fsnotify events on ptmx, since it's a shared resource */
 681         filp->f_mode |= FMODE_NONOTIFY;
 682
 683         retval = tty_alloc_file(filp);
 684         if (retval)
 685                 return retval;
 686
 687         /* find a device that is not in use. */
 688         mutex_lock(&devpts_mutex);
 689         index = devpts_new_index(inode);
 690         if (index < 0) {
 691                 retval = index;
 692                 mutex_unlock(&devpts_mutex);
 693                 goto err_file;
 694         }
 695
 696         mutex_unlock(&devpts_mutex);
 697
 698         mutex_lock(&tty_mutex);
 699         tty = tty_init_dev(ptm_driver, index);
 700
 701         if (IS_ERR(tty)) {
 702                 retval = PTR_ERR(tty);
 703                 goto out;
 704         }
 705
 706         /* The tty returned here is locked so we can safely
 707            drop the mutex */
 708         mutex_unlock(&tty_mutex);
 709
 710         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 711         tty->driver_data = inode;
 712
 713         tty_add_file(tty, filp);
 714
 715         slave_inode = devpts_pty_new(inode,
 716                         MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
 717                         tty->link);
 718         if (IS_ERR(slave_inode)) {
 719                 retval = PTR_ERR(slave_inode);
 720                 goto err_release;
 721         }
 722         tty->link->driver_data = slave_inode;
 723
 724         retval = ptm_driver->ops->open(tty, filp);
 725         if (retval)
 726                 goto err_release;
 727
 728         tty_unlock(tty);
 729         return 0;
 730 err_release:
 731         tty_unlock(tty);
 732         tty_release(inode, filp);
 733         return retval;
 734 out:
 735         mutex_unlock(&tty_mutex);
 736         devpts_kill_index(inode, index);
 737 err_file:
 738         tty_free_file(filp);
 739         return retval;
 740 }
 741
 742 static struct file_operations ptmx_fops;
 743
 744 static void __init unix98_pty_init(void)
 745 {
 746         ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 747                         TTY_DRIVER_RESET_TERMIOS |
 748                         TTY_DRIVER_REAL_RAW |
 749                         TTY_DRIVER_DYNAMIC_DEV |
 750                         TTY_DRIVER_DEVPTS_MEM |
 751                         TTY_DRIVER_DYNAMIC_ALLOC);
 752         if (IS_ERR(ptm_driver))
 753                 panic("Couldn't allocate Unix98 ptm driver");
 754         pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 755                         TTY_DRIVER_RESET_TERMIOS |
 756                         TTY_DRIVER_REAL_RAW |
 757                         TTY_DRIVER_DYNAMIC_DEV |
 758                         TTY_DRIVER_DEVPTS_MEM |
 759                         TTY_DRIVER_DYNAMIC_ALLOC);
 760         if (IS_ERR(pts_driver))
 761                 panic("Couldn't allocate Unix98 pts driver");
 762
 763         ptm_driver->driver_name = "pty_master";
 764         ptm_driver->name = "ptm";
 765         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 766         ptm_driver->minor_start = 0;
 767         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 768         ptm_driver->subtype = PTY_TYPE_MASTER;
 769         ptm_driver->init_termios = tty_std_termios;
 770         ptm_driver->init_termios.c_iflag = 0;
 771         ptm_driver->init_termios.c_oflag = 0;
 772         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 773         ptm_driver->init_termios.c_lflag = 0;
 774         ptm_driver->init_termios.c_ispeed = 38400;
 775         ptm_driver->init_termios.c_ospeed = 38400;
 776         ptm_driver->other = pts_driver;
 777         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 778
 779         pts_driver->driver_name = "pty_slave";
 780         pts_driver->name = "pts";
 781         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 782         pts_driver->minor_start = 0;
 783         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 784         pts_driver->subtype = PTY_TYPE_SLAVE;
 785         pts_driver->init_termios = tty_std_termios;
 786         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 787         pts_driver->init_termios.c_ispeed = 38400;
 788         pts_driver->init_termios.c_ospeed = 38400;
 789         pts_driver->other = ptm_driver;
 790         tty_set_operations(pts_driver, &pty_unix98_ops);
 791
 792         if (tty_register_driver(ptm_driver))
 793                 panic("Couldn't register Unix98 ptm driver");
 794         if (tty_register_driver(pts_driver))
 795                 panic("Couldn't register Unix98 pts driver");
 796
 797         /* Now create the /dev/ptmx special device */
 798         tty_default_fops(&ptmx_fops);
 799         ptmx_fops.open = ptmx_open;
 800
 801         cdev_init(&ptmx_cdev, &ptmx_fops);
 802         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 803             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 804                 panic("Couldn't register /dev/ptmx driver");
 805         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 806 }
 807
 808 #else
 809 static inline void unix98_pty_init(void) { }
 810 #endif
 811
 812 static int __init pty_init(void)
 813 {
 814         legacy_pty_init();
 815         unix98_pty_init();
 816         return 0;
 817 }
 818 module_init(pty_init);