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 #include <linux/poll.h>
  28
  29
  30 #ifdef CONFIG_UNIX98_PTYS
  31 static struct tty_driver *ptm_driver;
  32 static struct tty_driver *pts_driver;
  33 static DEFINE_MUTEX(devpts_mutex);
  34 #endif
  35
  36 static void pty_close(struct tty_struct *tty, struct file *filp)
  37 {
  38         BUG_ON(!tty);
  39         if (tty->driver->subtype == PTY_TYPE_MASTER)
  40                 WARN_ON(tty->count > 1);
  41         else {
  42                 if (test_bit(TTY_IO_ERROR, &tty->flags))
  43                         return;
  44                 if (tty->count > 2)
  45                         return;
  46         }
  47         set_bit(TTY_IO_ERROR, &tty->flags);
  48         wake_up_interruptible(&tty->read_wait);
  49         wake_up_interruptible(&tty->write_wait);
  50         tty->packet = 0;
  51         /* Review - krefs on tty_link ?? */
  52         if (!tty->link)
  53                 return;
  54         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  55         wake_up_interruptible(&tty->link->read_wait);
  56         wake_up_interruptible(&tty->link->write_wait);
  57         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  58                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  59 #ifdef CONFIG_UNIX98_PTYS
  60                 if (tty->driver == ptm_driver) {
  61                         mutex_lock(&devpts_mutex);
  62                         if (tty->link->driver_data)
  63                                 devpts_pty_kill(tty->link->driver_data);
  64                         mutex_unlock(&devpts_mutex);
  65                 }
  66 #endif
  67                 tty_unlock(tty);
  68                 tty_vhangup(tty->link);
  69                 tty_lock(tty);
  70         }
  71 }
  72
  73 /*
  74  * The unthrottle routine is called by the line discipline to signal
  75  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  76  * flag is always set, to force the line discipline to always call the
  77  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  78  * characters in the queue.  This is necessary since each time this
  79  * happens, we need to wake up any sleeping processes that could be
  80  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  81  * for the pty buffer to be drained.
  82  */
  83 static void pty_unthrottle(struct tty_struct *tty)
  84 {
  85         tty_wakeup(tty->link);
  86         set_bit(TTY_THROTTLED, &tty->flags);
  87 }
  88
  89 /**
  90  *      pty_space       -       report space left for writing
  91  *      @to: tty we are writing into
  92  *
  93  *      Limit the buffer space used by ptys to 8k.
  94  */
  95
  96 static int pty_space(struct tty_struct *to)
  97 {
  98         int n = tty_buffer_space_avail(to->port);
  99         return min(n, 8192);
 100 }
 101
 102 /**
 103  *      pty_write               -       write to a pty
 104  *      @tty: the tty we write from
 105  *      @buf: kernel buffer of data
 106  *      @count: bytes to write
 107  *
 108  *      Our "hardware" write method. Data is coming from the ldisc which
 109  *      may be in a non sleeping state. We simply throw this at the other
 110  *      end of the link as if we were an IRQ handler receiving stuff for
 111  *      the other side of the pty/tty pair.
 112  */
 113
 114 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 115 {
 116         struct tty_struct *to = tty->link;
 117
 118         if (tty->stopped)
 119                 return 0;
 120
 121         if (c > 0) {
 122                 /* Stuff the data into the input queue of the other end */
 123                 c = tty_insert_flip_string(to->port, buf, c);
 124                 /* And shovel */
 125                 if (c)
 126                         tty_flip_buffer_push(to->port);
 127         }
 128         return c;
 129 }
 130
 131 /**
 132  *      pty_write_room  -       write space
 133  *      @tty: tty we are writing from
 134  *
 135  *      Report how many bytes the ldisc can send into the queue for
 136  *      the other device.
 137  */
 138
 139 static int pty_write_room(struct tty_struct *tty)
 140 {
 141         if (tty->stopped)
 142                 return 0;
 143         return pty_space(tty->link);
 144 }
 145
 146 /**
 147  *      pty_chars_in_buffer     -       characters currently in our tx queue
 148  *      @tty: our tty
 149  *
 150  *      Report how much we have in the transmit queue. As everything is
 151  *      instantly at the other end this is easy to implement.
 152  */
 153
 154 static int pty_chars_in_buffer(struct tty_struct *tty)
 155 {
 156         return 0;
 157 }
 158
 159 /* Set the lock flag on a pty */
 160 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 161 {
 162         int val;
 163         if (get_user(val, arg))
 164                 return -EFAULT;
 165         if (val)
 166                 set_bit(TTY_PTY_LOCK, &tty->flags);
 167         else
 168                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 169         return 0;
 170 }
 171
 172 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
 173 {
 174         int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
 175         return put_user(locked, arg);
 176 }
 177
 178 /* Set the packet mode on a pty */
 179 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
 180 {
 181         int pktmode;
 182
 183         if (get_user(pktmode, arg))
 184                 return -EFAULT;
 185
 186         spin_lock_irq(&tty->ctrl_lock);
 187         if (pktmode) {
 188                 if (!tty->packet) {
 189                         tty->link->ctrl_status = 0;
 190                         smp_mb();
 191                         tty->packet = 1;
 192                 }
 193         } else
 194                 tty->packet = 0;
 195         spin_unlock_irq(&tty->ctrl_lock);
 196
 197         return 0;
 198 }
 199
 200 /* Get the packet mode of a pty */
 201 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
 202 {
 203         int pktmode = tty->packet;
 204         return put_user(pktmode, arg);
 205 }
 206
 207 /* Send a signal to the slave */
 208 static int pty_signal(struct tty_struct *tty, int sig)
 209 {
 210         struct pid *pgrp;
 211
 212         if (tty->link) {
 213                 pgrp = tty_get_pgrp(tty->link);
 214                 if (pgrp)
 215                         kill_pgrp(pgrp, sig, 1);
 216                 put_pid(pgrp);
 217         }
 218         return 0;
 219 }
 220
 221 static void pty_flush_buffer(struct tty_struct *tty)
 222 {
 223         struct tty_struct *to = tty->link;
 224
 225         if (!to)
 226                 return;
 227         /* tty_buffer_flush(to); FIXME */
 228         if (to->packet) {
 229                 spin_lock_irq(&tty->ctrl_lock);
 230                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 231                 wake_up_interruptible(&to->read_wait);
 232                 spin_unlock_irq(&tty->ctrl_lock);
 233         }
 234 }
 235
 236 static int pty_open(struct tty_struct *tty, struct file *filp)
 237 {
 238         if (!tty || !tty->link)
 239                 return -ENODEV;
 240
 241         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 242                 goto out;
 243         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 244                 goto out;
 245         if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
 246                 goto out;
 247
 248         clear_bit(TTY_IO_ERROR, &tty->flags);
 249         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 250         set_bit(TTY_THROTTLED, &tty->flags);
 251         return 0;
 252
 253 out:
 254         set_bit(TTY_IO_ERROR, &tty->flags);
 255         return -EIO;
 256 }
 257
 258 static void pty_set_termios(struct tty_struct *tty,
 259                                         struct ktermios *old_termios)
 260 {
 261         /* See if packet mode change of state. */
 262         if (tty->link && tty->link->packet) {
 263                 int extproc = (old_termios->c_lflag & EXTPROC) |
 264                                 (tty->termios.c_lflag & EXTPROC);
 265                 int old_flow = ((old_termios->c_iflag & IXON) &&
 266                                 (old_termios->c_cc[VSTOP] == '\023') &&
 267                                 (old_termios->c_cc[VSTART] == '\021'));
 268                 int new_flow = (I_IXON(tty) &&
 269                                 STOP_CHAR(tty) == '\023' &&
 270                                 START_CHAR(tty) == '\021');
 271                 if ((old_flow != new_flow) || extproc) {
 272                         spin_lock_irq(&tty->ctrl_lock);
 273                         if (old_flow != new_flow) {
 274                                 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
 275                                 if (new_flow)
 276                                         tty->ctrl_status |= TIOCPKT_DOSTOP;
 277                                 else
 278                                         tty->ctrl_status |= TIOCPKT_NOSTOP;
 279                         }
 280                         if (extproc)
 281                                 tty->ctrl_status |= TIOCPKT_IOCTL;
 282                         spin_unlock_irq(&tty->ctrl_lock);
 283                         wake_up_interruptible(&tty->link->read_wait);
 284                 }
 285         }
 286
 287         tty->termios.c_cflag &= ~(CSIZE | PARENB);
 288         tty->termios.c_cflag |= (CS8 | CREAD);
 289 }
 290
 291 /**
 292  *      pty_do_resize           -       resize event
 293  *      @tty: tty being resized
 294  *      @ws: window size being set.
 295  *
 296  *      Update the termios variables and send the necessary signals to
 297  *      peform a terminal resize correctly
 298  */
 299
 300 static int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 301 {
 302         struct pid *pgrp, *rpgrp;
 303         struct tty_struct *pty = tty->link;
 304
 305         /* For a PTY we need to lock the tty side */
 306         mutex_lock(&tty->winsize_mutex);
 307         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 308                 goto done;
 309
 310         /* Signal the foreground process group of both ptys */
 311         pgrp = tty_get_pgrp(tty);
 312         rpgrp = tty_get_pgrp(pty);
 313
 314         if (pgrp)
 315                 kill_pgrp(pgrp, SIGWINCH, 1);
 316         if (rpgrp != pgrp && rpgrp)
 317                 kill_pgrp(rpgrp, SIGWINCH, 1);
 318
 319         put_pid(pgrp);
 320         put_pid(rpgrp);
 321
 322         tty->winsize = *ws;
 323         pty->winsize = *ws;     /* Never used so will go away soon */
 324 done:
 325         mutex_unlock(&tty->winsize_mutex);
 326         return 0;
 327 }
 328
 329 /**
 330  *      pty_start - start() handler
 331  *      pty_stop  - stop() handler
 332  *      @tty: tty being flow-controlled
 333  *
 334  *      Propagates the TIOCPKT status to the master pty.
 335  *
 336  *      NB: only the master pty can be in packet mode so only the slave
 337  *          needs start()/stop() handlers
 338  */
 339 static void pty_start(struct tty_struct *tty)
 340 {
 341         unsigned long flags;
 342
 343         if (tty->link && tty->link->packet) {
 344                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 345                 tty->ctrl_status &= ~TIOCPKT_STOP;
 346                 tty->ctrl_status |= TIOCPKT_START;
 347                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 348                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
 349         }
 350 }
 351
 352 static void pty_stop(struct tty_struct *tty)
 353 {
 354         unsigned long flags;
 355
 356         if (tty->link && tty->link->packet) {
 357                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 358                 tty->ctrl_status &= ~TIOCPKT_START;
 359                 tty->ctrl_status |= TIOCPKT_STOP;
 360                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 361                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
 362         }
 363 }
 364
 365 /**
 366  *      pty_common_install              -       set up the pty pair
 367  *      @driver: the pty driver
 368  *      @tty: the tty being instantiated
 369  *      @legacy: true if this is BSD style
 370  *
 371  *      Perform the initial set up for the tty/pty pair. Called from the
 372  *      tty layer when the port is first opened.
 373  *
 374  *      Locking: the caller must hold the tty_mutex
 375  */
 376 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 377                 bool legacy)
 378 {
 379         struct tty_struct *o_tty;
 380         struct tty_port *ports[2];
 381         int idx = tty->index;
 382         int retval = -ENOMEM;
 383
 384         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
 385         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
 386         if (!ports[0] || !ports[1])
 387                 goto err;
 388         if (!try_module_get(driver->other->owner)) {
 389                 /* This cannot in fact currently happen */
 390                 goto err;
 391         }
 392         o_tty = alloc_tty_struct(driver->other, idx);
 393         if (!o_tty)
 394                 goto err_put_module;
 395
 396         if (legacy) {
 397                 /* We always use new tty termios data so we can do this
 398                    the easy way .. */
 399                 retval = tty_init_termios(tty);
 400                 if (retval)
 401                         goto err_deinit_tty;
 402
 403                 retval = tty_init_termios(o_tty);
 404                 if (retval)
 405                         goto err_free_termios;
 406
 407                 driver->other->ttys[idx] = o_tty;
 408                 driver->ttys[idx] = tty;
 409         } else {
 410                 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
 411                 tty->termios = driver->init_termios;
 412                 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
 413                 o_tty->termios = driver->other->init_termios;
 414         }
 415
 416         /*
 417          * Everything allocated ... set up the o_tty structure.
 418          */
 419         tty_driver_kref_get(driver->other);
 420         if (driver->subtype == PTY_TYPE_MASTER)
 421                 o_tty->count++;
 422         /* Establish the links in both directions */
 423         tty->link   = o_tty;
 424         o_tty->link = tty;
 425         tty_port_init(ports[0]);
 426         tty_port_init(ports[1]);
 427         o_tty->port = ports[0];
 428         tty->port = ports[1];
 429         o_tty->port->itty = o_tty;
 430
 431         tty_driver_kref_get(driver);
 432         tty->count++;
 433         return 0;
 434 err_free_termios:
 435         if (legacy)
 436                 tty_free_termios(tty);
 437 err_deinit_tty:
 438         deinitialize_tty_struct(o_tty);
 439         free_tty_struct(o_tty);
 440 err_put_module:
 441         module_put(driver->other->owner);
 442 err:
 443         kfree(ports[0]);
 444         kfree(ports[1]);
 445         return retval;
 446 }
 447
 448 static void pty_cleanup(struct tty_struct *tty)
 449 {
 450         tty_port_put(tty->port);
 451 }
 452
 453 /* Traditional BSD devices */
 454 #ifdef CONFIG_LEGACY_PTYS
 455
 456 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 457 {
 458         return pty_common_install(driver, tty, true);
 459 }
 460
 461 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
 462 {
 463         struct tty_struct *pair = tty->link;
 464         driver->ttys[tty->index] = NULL;
 465         if (pair)
 466                 pair->driver->ttys[pair->index] = NULL;
 467 }
 468
 469 static int pty_bsd_ioctl(struct tty_struct *tty,
 470                          unsigned int cmd, unsigned long arg)
 471 {
 472         switch (cmd) {
 473         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 474                 return pty_set_lock(tty, (int __user *) arg);
 475         case TIOCGPTLCK: /* Get PT Lock status */
 476                 return pty_get_lock(tty, (int __user *)arg);
 477         case TIOCPKT: /* Set PT packet mode */
 478                 return pty_set_pktmode(tty, (int __user *)arg);
 479         case TIOCGPKT: /* Get PT packet mode */
 480                 return pty_get_pktmode(tty, (int __user *)arg);
 481         case TIOCSIG:    /* Send signal to other side of pty */
 482                 return pty_signal(tty, (int) arg);
 483         case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
 484                 return -EINVAL;
 485         }
 486         return -ENOIOCTLCMD;
 487 }
 488
 489 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 490 module_param(legacy_count, int, 0);
 491
 492 /*
 493  * The master side of a pty can do TIOCSPTLCK and thus
 494  * has pty_bsd_ioctl.
 495  */
 496 static const struct tty_operations master_pty_ops_bsd = {
 497         .install = pty_install,
 498         .open = pty_open,
 499         .close = pty_close,
 500         .write = pty_write,
 501         .write_room = pty_write_room,
 502         .flush_buffer = pty_flush_buffer,
 503         .chars_in_buffer = pty_chars_in_buffer,
 504         .unthrottle = pty_unthrottle,
 505         .ioctl = pty_bsd_ioctl,
 506         .cleanup = pty_cleanup,
 507         .resize = pty_resize,
 508         .remove = pty_remove
 509 };
 510
 511 static const struct tty_operations slave_pty_ops_bsd = {
 512         .install = pty_install,
 513         .open = pty_open,
 514         .close = pty_close,
 515         .write = pty_write,
 516         .write_room = pty_write_room,
 517         .flush_buffer = pty_flush_buffer,
 518         .chars_in_buffer = pty_chars_in_buffer,
 519         .unthrottle = pty_unthrottle,
 520         .set_termios = pty_set_termios,
 521         .cleanup = pty_cleanup,
 522         .resize = pty_resize,
 523         .start = pty_start,
 524         .stop = pty_stop,
 525         .remove = pty_remove
 526 };
 527
 528 static void __init legacy_pty_init(void)
 529 {
 530         struct tty_driver *pty_driver, *pty_slave_driver;
 531
 532         if (legacy_count <= 0)
 533                 return;
 534
 535         pty_driver = tty_alloc_driver(legacy_count,
 536                         TTY_DRIVER_RESET_TERMIOS |
 537                         TTY_DRIVER_REAL_RAW |
 538                         TTY_DRIVER_DYNAMIC_ALLOC);
 539         if (IS_ERR(pty_driver))
 540                 panic("Couldn't allocate pty driver");
 541
 542         pty_slave_driver = tty_alloc_driver(legacy_count,
 543                         TTY_DRIVER_RESET_TERMIOS |
 544                         TTY_DRIVER_REAL_RAW |
 545                         TTY_DRIVER_DYNAMIC_ALLOC);
 546         if (IS_ERR(pty_slave_driver))
 547                 panic("Couldn't allocate pty slave driver");
 548
 549         pty_driver->driver_name = "pty_master";
 550         pty_driver->name = "pty";
 551         pty_driver->major = PTY_MASTER_MAJOR;
 552         pty_driver->minor_start = 0;
 553         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 554         pty_driver->subtype = PTY_TYPE_MASTER;
 555         pty_driver->init_termios = tty_std_termios;
 556         pty_driver->init_termios.c_iflag = 0;
 557         pty_driver->init_termios.c_oflag = 0;
 558         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 559         pty_driver->init_termios.c_lflag = 0;
 560         pty_driver->init_termios.c_ispeed = 38400;
 561         pty_driver->init_termios.c_ospeed = 38400;
 562         pty_driver->other = pty_slave_driver;
 563         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 564
 565         pty_slave_driver->driver_name = "pty_slave";
 566         pty_slave_driver->name = "ttyp";
 567         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 568         pty_slave_driver->minor_start = 0;
 569         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 570         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 571         pty_slave_driver->init_termios = tty_std_termios;
 572         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 573         pty_slave_driver->init_termios.c_ispeed = 38400;
 574         pty_slave_driver->init_termios.c_ospeed = 38400;
 575         pty_slave_driver->other = pty_driver;
 576         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 577
 578         if (tty_register_driver(pty_driver))
 579                 panic("Couldn't register pty driver");
 580         if (tty_register_driver(pty_slave_driver))
 581                 panic("Couldn't register pty slave driver");
 582 }
 583 #else
 584 static inline void legacy_pty_init(void) { }
 585 #endif
 586
 587 /* Unix98 devices */
 588 #ifdef CONFIG_UNIX98_PTYS
 589
 590 static struct cdev ptmx_cdev;
 591
 592 static int pty_unix98_ioctl(struct tty_struct *tty,
 593                             unsigned int cmd, unsigned long arg)
 594 {
 595         switch (cmd) {
 596         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 597                 return pty_set_lock(tty, (int __user *)arg);
 598         case TIOCGPTLCK: /* Get PT Lock status */
 599                 return pty_get_lock(tty, (int __user *)arg);
 600         case TIOCPKT: /* Set PT packet mode */
 601                 return pty_set_pktmode(tty, (int __user *)arg);
 602         case TIOCGPKT: /* Get PT packet mode */
 603                 return pty_get_pktmode(tty, (int __user *)arg);
 604         case TIOCGPTN: /* Get PT Number */
 605                 return put_user(tty->index, (unsigned int __user *)arg);
 606         case TIOCSIG:    /* Send signal to other side of pty */
 607                 return pty_signal(tty, (int) arg);
 608         }
 609
 610         return -ENOIOCTLCMD;
 611 }
 612
 613 /**
 614  *      ptm_unix98_lookup       -       find a pty master
 615  *      @driver: ptm driver
 616  *      @idx: tty index
 617  *
 618  *      Look up a pty master device. Called under the tty_mutex for now.
 619  *      This provides our locking.
 620  */
 621
 622 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 623                 struct inode *ptm_inode, int idx)
 624 {
 625         /* Master must be open via /dev/ptmx */
 626         return ERR_PTR(-EIO);
 627 }
 628
 629 /**
 630  *      pts_unix98_lookup       -       find a pty slave
 631  *      @driver: pts driver
 632  *      @idx: tty index
 633  *
 634  *      Look up a pty master device. Called under the tty_mutex for now.
 635  *      This provides our locking for the tty pointer.
 636  */
 637
 638 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 639                 struct inode *pts_inode, int idx)
 640 {
 641         struct tty_struct *tty;
 642
 643         mutex_lock(&devpts_mutex);
 644         tty = devpts_get_priv(pts_inode);
 645         mutex_unlock(&devpts_mutex);
 646         /* Master must be open before slave */
 647         if (!tty)
 648                 return ERR_PTR(-EIO);
 649         return tty;
 650 }
 651
 652 /* We have no need to install and remove our tty objects as devpts does all
 653    the work for us */
 654
 655 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 656 {
 657         return pty_common_install(driver, tty, false);
 658 }
 659
 660 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 661 {
 662 }
 663
 664 /* this is called once with whichever end is closed last */
 665 static void pty_unix98_shutdown(struct tty_struct *tty)
 666 {
 667         devpts_kill_index(tty->driver_data, tty->index);
 668 }
 669
 670 static const struct tty_operations ptm_unix98_ops = {
 671         .lookup = ptm_unix98_lookup,
 672         .install = pty_unix98_install,
 673         .remove = pty_unix98_remove,
 674         .open = pty_open,
 675         .close = pty_close,
 676         .write = pty_write,
 677         .write_room = pty_write_room,
 678         .flush_buffer = pty_flush_buffer,
 679         .chars_in_buffer = pty_chars_in_buffer,
 680         .unthrottle = pty_unthrottle,
 681         .ioctl = pty_unix98_ioctl,
 682         .resize = pty_resize,
 683         .shutdown = pty_unix98_shutdown,
 684         .cleanup = pty_cleanup
 685 };
 686
 687 static const struct tty_operations pty_unix98_ops = {
 688         .lookup = pts_unix98_lookup,
 689         .install = pty_unix98_install,
 690         .remove = pty_unix98_remove,
 691         .open = pty_open,
 692         .close = pty_close,
 693         .write = pty_write,
 694         .write_room = pty_write_room,
 695         .flush_buffer = pty_flush_buffer,
 696         .chars_in_buffer = pty_chars_in_buffer,
 697         .unthrottle = pty_unthrottle,
 698         .set_termios = pty_set_termios,
 699         .start = pty_start,
 700         .stop = pty_stop,
 701         .shutdown = pty_unix98_shutdown,
 702         .cleanup = pty_cleanup,
 703 };
 704
 705 /**
 706  *      ptmx_open               -       open a unix 98 pty master
 707  *      @inode: inode of device file
 708  *      @filp: file pointer to tty
 709  *
 710  *      Allocate a unix98 pty master device from the ptmx driver.
 711  *
 712  *      Locking: tty_mutex protects the init_dev work. tty->count should
 713  *              protect the rest.
 714  *              allocated_ptys_lock handles the list of free pty numbers
 715  */
 716
 717 static int ptmx_open(struct inode *inode, struct file *filp)
 718 {
 719         struct tty_struct *tty;
 720         struct inode *slave_inode;
 721         int retval;
 722         int index;
 723
 724         nonseekable_open(inode, filp);
 725
 726         /* We refuse fsnotify events on ptmx, since it's a shared resource */
 727         filp->f_mode |= FMODE_NONOTIFY;
 728
 729         retval = tty_alloc_file(filp);
 730         if (retval)
 731                 return retval;
 732
 733         /* find a device that is not in use. */
 734         mutex_lock(&devpts_mutex);
 735         index = devpts_new_index(inode);
 736         if (index < 0) {
 737                 retval = index;
 738                 mutex_unlock(&devpts_mutex);
 739                 goto err_file;
 740         }
 741
 742         mutex_unlock(&devpts_mutex);
 743
 744         mutex_lock(&tty_mutex);
 745         tty = tty_init_dev(ptm_driver, index);
 746
 747         if (IS_ERR(tty)) {
 748                 retval = PTR_ERR(tty);
 749                 goto out;
 750         }
 751
 752         /* The tty returned here is locked so we can safely
 753            drop the mutex */
 754         mutex_unlock(&tty_mutex);
 755
 756         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 757         tty->driver_data = inode;
 758
 759         tty_add_file(tty, filp);
 760
 761         slave_inode = devpts_pty_new(inode,
 762                         MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index,
 763                         tty->link);
 764         if (IS_ERR(slave_inode)) {
 765                 retval = PTR_ERR(slave_inode);
 766                 goto err_release;
 767         }
 768         tty->link->driver_data = slave_inode;
 769
 770         retval = ptm_driver->ops->open(tty, filp);
 771         if (retval)
 772                 goto err_release;
 773
 774         tty_unlock(tty);
 775         return 0;
 776 err_release:
 777         tty_unlock(tty);
 778         tty_release(inode, filp);
 779         return retval;
 780 out:
 781         mutex_unlock(&tty_mutex);
 782         devpts_kill_index(inode, index);
 783 err_file:
 784         tty_free_file(filp);
 785         return retval;
 786 }
 787
 788 static struct file_operations ptmx_fops;
 789
 790 static void __init unix98_pty_init(void)
 791 {
 792         ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 793                         TTY_DRIVER_RESET_TERMIOS |
 794                         TTY_DRIVER_REAL_RAW |
 795                         TTY_DRIVER_DYNAMIC_DEV |
 796                         TTY_DRIVER_DEVPTS_MEM |
 797                         TTY_DRIVER_DYNAMIC_ALLOC);
 798         if (IS_ERR(ptm_driver))
 799                 panic("Couldn't allocate Unix98 ptm driver");
 800         pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 801                         TTY_DRIVER_RESET_TERMIOS |
 802                         TTY_DRIVER_REAL_RAW |
 803                         TTY_DRIVER_DYNAMIC_DEV |
 804                         TTY_DRIVER_DEVPTS_MEM |
 805                         TTY_DRIVER_DYNAMIC_ALLOC);
 806         if (IS_ERR(pts_driver))
 807                 panic("Couldn't allocate Unix98 pts driver");
 808
 809         ptm_driver->driver_name = "pty_master";
 810         ptm_driver->name = "ptm";
 811         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 812         ptm_driver->minor_start = 0;
 813         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 814         ptm_driver->subtype = PTY_TYPE_MASTER;
 815         ptm_driver->init_termios = tty_std_termios;
 816         ptm_driver->init_termios.c_iflag = 0;
 817         ptm_driver->init_termios.c_oflag = 0;
 818         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 819         ptm_driver->init_termios.c_lflag = 0;
 820         ptm_driver->init_termios.c_ispeed = 38400;
 821         ptm_driver->init_termios.c_ospeed = 38400;
 822         ptm_driver->other = pts_driver;
 823         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 824
 825         pts_driver->driver_name = "pty_slave";
 826         pts_driver->name = "pts";
 827         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 828         pts_driver->minor_start = 0;
 829         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 830         pts_driver->subtype = PTY_TYPE_SLAVE;
 831         pts_driver->init_termios = tty_std_termios;
 832         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 833         pts_driver->init_termios.c_ispeed = 38400;
 834         pts_driver->init_termios.c_ospeed = 38400;
 835         pts_driver->other = ptm_driver;
 836         tty_set_operations(pts_driver, &pty_unix98_ops);
 837
 838         if (tty_register_driver(ptm_driver))
 839                 panic("Couldn't register Unix98 ptm driver");
 840         if (tty_register_driver(pts_driver))
 841                 panic("Couldn't register Unix98 pts driver");
 842
 843         /* Now create the /dev/ptmx special device */
 844         tty_default_fops(&ptmx_fops);
 845         ptmx_fops.open = ptmx_open;
 846
 847         cdev_init(&ptmx_cdev, &ptmx_fops);
 848         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 849             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 850                 panic("Couldn't register /dev/ptmx driver");
 851         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 852 }
 853
 854 #else
 855 static inline void unix98_pty_init(void) { }
 856 #endif
 857
 858 static int __init pty_init(void)
 859 {
 860         legacy_pty_init();
 861         unix98_pty_init();
 862         return 0;
 863 }
 864 module_init(pty_init);