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