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