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  *  When reading this code see also fs/devpts. In particular note that the
   8  *  driver_data field is used by the devpts side as a binding to the devpts
   9  *  inode.
  10  */
  11
  12 #include <linux/module.h>
  13
  14 #include <linux/errno.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_flip.h>
  18 #include <linux/fcntl.h>
  19 #include <linux/sched.h>
  20 #include <linux/string.h>
  21 #include <linux/major.h>
  22 #include <linux/mm.h>
  23 #include <linux/init.h>
  24 #include <linux/sysctl.h>
  25 #include <linux/device.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/bitops.h>
  28 #include <linux/devpts_fs.h>
  29 #include <linux/slab.h>
  30
  31 #include <asm/system.h>
  32
  33 #ifdef CONFIG_UNIX98_PTYS
  34 static struct tty_driver *ptm_driver;
  35 static struct tty_driver *pts_driver;
  36 #endif
  37
  38 static void pty_close(struct tty_struct *tty, struct file *filp)
  39 {
  40         BUG_ON(!tty);
  41         if (tty->driver->subtype == PTY_TYPE_MASTER)
  42                 WARN_ON(tty->count > 1);
  43         else {
  44                 if (tty->count > 2)
  45                         return;
  46         }
  47         wake_up_interruptible(&tty->read_wait);
  48         wake_up_interruptible(&tty->write_wait);
  49         tty->packet = 0;
  50         if (!tty->link)
  51                 return;
  52         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  53         wake_up_interruptible(&tty->link->read_wait);
  54         wake_up_interruptible(&tty->link->write_wait);
  55         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  56                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  57 #ifdef CONFIG_UNIX98_PTYS
  58                 if (tty->driver == ptm_driver)
  59                         devpts_pty_kill(tty->link);
  60 #endif
  61                 tty_unlock();
  62                 tty_vhangup(tty->link);
  63                 tty_lock();
  64         }
  65 }
  66
  67 /*
  68  * The unthrottle routine is called by the line discipline to signal
  69  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  70  * flag is always set, to force the line discipline to always call the
  71  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  72  * characters in the queue.  This is necessary since each time this
  73  * happens, we need to wake up any sleeping processes that could be
  74  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  75  * for the pty buffer to be drained.
  76  */
  77 static void pty_unthrottle(struct tty_struct *tty)
  78 {
  79         tty_wakeup(tty->link);
  80         set_bit(TTY_THROTTLED, &tty->flags);
  81 }
  82
  83 /**
  84  *      pty_space       -       report space left for writing
  85  *      @to: tty we are writing into
  86  *
  87  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  88  *      allows a lot of overspill room for echo and other fun messes to
  89  *      be handled properly
  90  */
  91
  92 static int pty_space(struct tty_struct *to)
  93 {
  94         int n = 8192 - to->buf.memory_used;
  95         if (n < 0)
  96                 return 0;
  97         return n;
  98 }
  99
 100 /**
 101  *      pty_write               -       write to a pty
 102  *      @tty: the tty we write from
 103  *      @buf: kernel buffer of data
 104  *      @count: bytes to write
 105  *
 106  *      Our "hardware" write method. Data is coming from the ldisc which
 107  *      may be in a non sleeping state. We simply throw this at the other
 108  *      end of the link as if we were an IRQ handler receiving stuff for
 109  *      the other side of the pty/tty pair.
 110  */
 111
 112 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 113 {
 114         struct tty_struct *to = tty->link;
 115
 116         if (tty->stopped)
 117                 return 0;
 118
 119         if (c > 0) {
 120                 /* Stuff the data into the input queue of the other end */
 121                 c = tty_insert_flip_string(to, buf, c);
 122                 /* And shovel */
 123                 if (c) {
 124                         tty_flip_buffer_push(to);
 125                         tty_wakeup(tty);
 126                 }
 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 /* Send a signal to the slave */
 173 static int pty_signal(struct tty_struct *tty, int sig)
 174 {
 175         unsigned long flags;
 176         struct pid *pgrp;
 177
 178         if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
 179                 return -EINVAL;
 180
 181         if (tty->link) {
 182                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 183                 pgrp = get_pid(tty->link->pgrp);
 184                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 185
 186                 kill_pgrp(pgrp, sig, 1);
 187                 put_pid(pgrp);
 188         }
 189         return 0;
 190 }
 191
 192 static void pty_flush_buffer(struct tty_struct *tty)
 193 {
 194         struct tty_struct *to = tty->link;
 195         unsigned long flags;
 196
 197         if (!to)
 198                 return;
 199         /* tty_buffer_flush(to); FIXME */
 200         if (to->packet) {
 201                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 202                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 203                 wake_up_interruptible(&to->read_wait);
 204                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 205         }
 206 }
 207
 208 static int pty_open(struct tty_struct *tty, struct file *filp)
 209 {
 210         int     retval = -ENODEV;
 211
 212         if (!tty || !tty->link)
 213                 goto out;
 214
 215         retval = -EIO;
 216         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 217                 goto out;
 218         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 219                 goto out;
 220         if (tty->link->count != 1)
 221                 goto out;
 222
 223         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 224         set_bit(TTY_THROTTLED, &tty->flags);
 225         retval = 0;
 226 out:
 227         return retval;
 228 }
 229
 230 static void pty_set_termios(struct tty_struct *tty,
 231                                         struct ktermios *old_termios)
 232 {
 233         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 234         tty->termios->c_cflag |= (CS8 | CREAD);
 235 }
 236
 237 /**
 238  *      pty_do_resize           -       resize event
 239  *      @tty: tty being resized
 240  *      @ws: window size being set.
 241  *
 242  *      Update the termios variables and send the necessary signals to
 243  *      peform a terminal resize correctly
 244  */
 245
 246 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 247 {
 248         struct pid *pgrp, *rpgrp;
 249         unsigned long flags;
 250         struct tty_struct *pty = tty->link;
 251
 252         /* For a PTY we need to lock the tty side */
 253         mutex_lock(&tty->termios_mutex);
 254         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 255                 goto done;
 256
 257         /* Get the PID values and reference them so we can
 258            avoid holding the tty ctrl lock while sending signals.
 259            We need to lock these individually however. */
 260
 261         spin_lock_irqsave(&tty->ctrl_lock, flags);
 262         pgrp = get_pid(tty->pgrp);
 263         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 264
 265         spin_lock_irqsave(&pty->ctrl_lock, flags);
 266         rpgrp = get_pid(pty->pgrp);
 267         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 268
 269         if (pgrp)
 270                 kill_pgrp(pgrp, SIGWINCH, 1);
 271         if (rpgrp != pgrp && rpgrp)
 272                 kill_pgrp(rpgrp, SIGWINCH, 1);
 273
 274         put_pid(pgrp);
 275         put_pid(rpgrp);
 276
 277         tty->winsize = *ws;
 278         pty->winsize = *ws;     /* Never used so will go away soon */
 279 done:
 280         mutex_unlock(&tty->termios_mutex);
 281         return 0;
 282 }
 283
 284 /* Traditional BSD devices */
 285 #ifdef CONFIG_LEGACY_PTYS
 286
 287 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 288 {
 289         struct tty_struct *o_tty;
 290         int idx = tty->index;
 291         int retval;
 292
 293         o_tty = alloc_tty_struct();
 294         if (!o_tty)
 295                 return -ENOMEM;
 296         if (!try_module_get(driver->other->owner)) {
 297                 /* This cannot in fact currently happen */
 298                 retval = -ENOMEM;
 299                 goto err_free_tty;
 300         }
 301         initialize_tty_struct(o_tty, driver->other, idx);
 302
 303         /* We always use new tty termios data so we can do this
 304            the easy way .. */
 305         retval = tty_init_termios(tty);
 306         if (retval)
 307                 goto err_deinit_tty;
 308
 309         retval = tty_init_termios(o_tty);
 310         if (retval)
 311                 goto err_free_termios;
 312
 313         /*
 314          * Everything allocated ... set up the o_tty structure.
 315          */
 316         driver->other->ttys[idx] = o_tty;
 317         tty_driver_kref_get(driver->other);
 318         if (driver->subtype == PTY_TYPE_MASTER)
 319                 o_tty->count++;
 320         /* Establish the links in both directions */
 321         tty->link   = o_tty;
 322         o_tty->link = tty;
 323
 324         tty_driver_kref_get(driver);
 325         tty->count++;
 326         driver->ttys[idx] = tty;
 327         return 0;
 328 err_free_termios:
 329         tty_free_termios(tty);
 330 err_deinit_tty:
 331         deinitialize_tty_struct(o_tty);
 332         module_put(o_tty->driver->owner);
 333 err_free_tty:
 334         free_tty_struct(o_tty);
 335         return retval;
 336 }
 337
 338 static int pty_bsd_ioctl(struct tty_struct *tty,
 339                          unsigned int cmd, unsigned long arg)
 340 {
 341         switch (cmd) {
 342         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 343                 return pty_set_lock(tty, (int __user *) arg);
 344         case TIOCSIG:    /* Send signal to other side of pty */
 345                 return pty_signal(tty, (int) arg);
 346         }
 347         return -ENOIOCTLCMD;
 348 }
 349
 350 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 351 module_param(legacy_count, int, 0);
 352
 353 /*
 354  * The master side of a pty can do TIOCSPTLCK and thus
 355  * has pty_bsd_ioctl.
 356  */
 357 static const struct tty_operations master_pty_ops_bsd = {
 358         .install = pty_install,
 359         .open = pty_open,
 360         .close = pty_close,
 361         .write = pty_write,
 362         .write_room = pty_write_room,
 363         .flush_buffer = pty_flush_buffer,
 364         .chars_in_buffer = pty_chars_in_buffer,
 365         .unthrottle = pty_unthrottle,
 366         .set_termios = pty_set_termios,
 367         .ioctl = pty_bsd_ioctl,
 368         .resize = pty_resize
 369 };
 370
 371 static const struct tty_operations slave_pty_ops_bsd = {
 372         .install = pty_install,
 373         .open = pty_open,
 374         .close = pty_close,
 375         .write = pty_write,
 376         .write_room = pty_write_room,
 377         .flush_buffer = pty_flush_buffer,
 378         .chars_in_buffer = pty_chars_in_buffer,
 379         .unthrottle = pty_unthrottle,
 380         .set_termios = pty_set_termios,
 381         .resize = pty_resize
 382 };
 383
 384 static void __init legacy_pty_init(void)
 385 {
 386         struct tty_driver *pty_driver, *pty_slave_driver;
 387
 388         if (legacy_count <= 0)
 389                 return;
 390
 391         pty_driver = alloc_tty_driver(legacy_count);
 392         if (!pty_driver)
 393                 panic("Couldn't allocate pty driver");
 394
 395         pty_slave_driver = alloc_tty_driver(legacy_count);
 396         if (!pty_slave_driver)
 397                 panic("Couldn't allocate pty slave driver");
 398
 399         pty_driver->owner = THIS_MODULE;
 400         pty_driver->driver_name = "pty_master";
 401         pty_driver->name = "pty";
 402         pty_driver->major = PTY_MASTER_MAJOR;
 403         pty_driver->minor_start = 0;
 404         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 405         pty_driver->subtype = PTY_TYPE_MASTER;
 406         pty_driver->init_termios = tty_std_termios;
 407         pty_driver->init_termios.c_iflag = 0;
 408         pty_driver->init_termios.c_oflag = 0;
 409         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 410         pty_driver->init_termios.c_lflag = 0;
 411         pty_driver->init_termios.c_ispeed = 38400;
 412         pty_driver->init_termios.c_ospeed = 38400;
 413         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 414         pty_driver->other = pty_slave_driver;
 415         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 416
 417         pty_slave_driver->owner = THIS_MODULE;
 418         pty_slave_driver->driver_name = "pty_slave";
 419         pty_slave_driver->name = "ttyp";
 420         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 421         pty_slave_driver->minor_start = 0;
 422         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 423         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 424         pty_slave_driver->init_termios = tty_std_termios;
 425         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 426         pty_slave_driver->init_termios.c_ispeed = 38400;
 427         pty_slave_driver->init_termios.c_ospeed = 38400;
 428         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 429                                         TTY_DRIVER_REAL_RAW;
 430         pty_slave_driver->other = pty_driver;
 431         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 432
 433         if (tty_register_driver(pty_driver))
 434                 panic("Couldn't register pty driver");
 435         if (tty_register_driver(pty_slave_driver))
 436                 panic("Couldn't register pty slave driver");
 437 }
 438 #else
 439 static inline void legacy_pty_init(void) { }
 440 #endif
 441
 442 /* Unix98 devices */
 443 #ifdef CONFIG_UNIX98_PTYS
 444 /*
 445  * sysctl support for setting limits on the number of Unix98 ptys allocated.
 446  * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
 447  */
 448 int pty_limit = NR_UNIX98_PTY_DEFAULT;
 449 static int pty_limit_min;
 450 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 451 static int tty_count;
 452 static int pty_count;
 453
 454 static inline void pty_inc_count(void)
 455 {
 456         pty_count = (++tty_count) / 2;
 457 }
 458
 459 static inline void pty_dec_count(void)
 460 {
 461         pty_count = (--tty_count) / 2;
 462 }
 463
 464 static struct cdev ptmx_cdev;
 465
 466 static struct ctl_table pty_table[] = {
 467         {
 468                 .procname       = "max",
 469                 .maxlen         = sizeof(int),
 470                 .mode           = 0644,
 471                 .data           = &pty_limit,
 472                 .proc_handler   = proc_dointvec_minmax,
 473                 .extra1         = &pty_limit_min,
 474                 .extra2         = &pty_limit_max,
 475         }, {
 476                 .procname       = "nr",
 477                 .maxlen         = sizeof(int),
 478                 .mode           = 0444,
 479                 .data           = &pty_count,
 480                 .proc_handler   = proc_dointvec,
 481         },
 482         {}
 483 };
 484
 485 static struct ctl_table pty_kern_table[] = {
 486         {
 487                 .procname       = "pty",
 488                 .mode           = 0555,
 489                 .child          = pty_table,
 490         },
 491         {}
 492 };
 493
 494 static struct ctl_table pty_root_table[] = {
 495         {
 496                 .procname       = "kernel",
 497                 .mode           = 0555,
 498                 .child          = pty_kern_table,
 499         },
 500         {}
 501 };
 502
 503
 504 static int pty_unix98_ioctl(struct tty_struct *tty,
 505                             unsigned int cmd, unsigned long arg)
 506 {
 507         switch (cmd) {
 508         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 509                 return pty_set_lock(tty, (int __user *)arg);
 510         case TIOCGPTN: /* Get PT Number */
 511                 return put_user(tty->index, (unsigned int __user *)arg);
 512         case TIOCSIG:    /* Send signal to other side of pty */
 513                 return pty_signal(tty, (int) arg);
 514         }
 515
 516         return -ENOIOCTLCMD;
 517 }
 518
 519 /**
 520  *      ptm_unix98_lookup       -       find a pty master
 521  *      @driver: ptm driver
 522  *      @idx: tty index
 523  *
 524  *      Look up a pty master device. Called under the tty_mutex for now.
 525  *      This provides our locking.
 526  */
 527
 528 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 529                 struct inode *ptm_inode, int idx)
 530 {
 531         struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
 532         if (tty)
 533                 tty = tty->link;
 534         return tty;
 535 }
 536
 537 /**
 538  *      pts_unix98_lookup       -       find a pty slave
 539  *      @driver: pts driver
 540  *      @idx: tty index
 541  *
 542  *      Look up a pty master device. Called under the tty_mutex for now.
 543  *      This provides our locking.
 544  */
 545
 546 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 547                 struct inode *pts_inode, int idx)
 548 {
 549         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 550         /* Master must be open before slave */
 551         if (!tty)
 552                 return ERR_PTR(-EIO);
 553         return tty;
 554 }
 555
 556 static void pty_unix98_shutdown(struct tty_struct *tty)
 557 {
 558         tty_driver_remove_tty(tty->driver, tty);
 559         /* We have our own method as we don't use the tty index */
 560         kfree(tty->termios);
 561 }
 562
 563 /* We have no need to install and remove our tty objects as devpts does all
 564    the work for us */
 565
 566 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 567 {
 568         struct tty_struct *o_tty;
 569         int idx = tty->index;
 570
 571         o_tty = alloc_tty_struct();
 572         if (!o_tty)
 573                 return -ENOMEM;
 574         if (!try_module_get(driver->other->owner)) {
 575                 /* This cannot in fact currently happen */
 576                 goto err_free_tty;
 577         }
 578         initialize_tty_struct(o_tty, driver->other, idx);
 579
 580         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 581         if (tty->termios == NULL)
 582                 goto err_free_mem;
 583         *tty->termios = driver->init_termios;
 584         tty->termios_locked = tty->termios + 1;
 585
 586         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 587         if (o_tty->termios == NULL)
 588                 goto err_free_mem;
 589         *o_tty->termios = driver->other->init_termios;
 590         o_tty->termios_locked = o_tty->termios + 1;
 591
 592         tty_driver_kref_get(driver->other);
 593         if (driver->subtype == PTY_TYPE_MASTER)
 594                 o_tty->count++;
 595         /* Establish the links in both directions */
 596         tty->link   = o_tty;
 597         o_tty->link = tty;
 598         /*
 599          * All structures have been allocated, so now we install them.
 600          * Failures after this point use release_tty to clean up, so
 601          * there's no need to null out the local pointers.
 602          */
 603         tty_driver_kref_get(driver);
 604         tty->count++;
 605         pty_inc_count(); /* tty */
 606         pty_inc_count(); /* tty->link */
 607         return 0;
 608 err_free_mem:
 609         deinitialize_tty_struct(o_tty);
 610         kfree(o_tty->termios);
 611         kfree(tty->termios);
 612         module_put(o_tty->driver->owner);
 613 err_free_tty:
 614         free_tty_struct(o_tty);
 615         return -ENOMEM;
 616 }
 617
 618 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 619 {
 620         pty_dec_count();
 621 }
 622
 623 static const struct tty_operations ptm_unix98_ops = {
 624         .lookup = ptm_unix98_lookup,
 625         .install = pty_unix98_install,
 626         .remove = pty_unix98_remove,
 627         .open = pty_open,
 628         .close = pty_close,
 629         .write = pty_write,
 630         .write_room = pty_write_room,
 631         .flush_buffer = pty_flush_buffer,
 632         .chars_in_buffer = pty_chars_in_buffer,
 633         .unthrottle = pty_unthrottle,
 634         .set_termios = pty_set_termios,
 635         .ioctl = pty_unix98_ioctl,
 636         .shutdown = pty_unix98_shutdown,
 637         .resize = pty_resize
 638 };
 639
 640 static const struct tty_operations pty_unix98_ops = {
 641         .lookup = pts_unix98_lookup,
 642         .install = pty_unix98_install,
 643         .remove = pty_unix98_remove,
 644         .open = pty_open,
 645         .close = pty_close,
 646         .write = pty_write,
 647         .write_room = pty_write_room,
 648         .flush_buffer = pty_flush_buffer,
 649         .chars_in_buffer = pty_chars_in_buffer,
 650         .unthrottle = pty_unthrottle,
 651         .set_termios = pty_set_termios,
 652         .shutdown = pty_unix98_shutdown
 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         int retval;
 671         int index;
 672
 673         nonseekable_open(inode, filp);
 674
 675         /* We refuse fsnotify events on ptmx, since it's a shared resource */
 676         filp->f_mode |= FMODE_NONOTIFY;
 677
 678         retval = tty_alloc_file(filp);
 679         if (retval)
 680                 return retval;
 681
 682         /* find a device that is not in use. */
 683         tty_lock();
 684         index = devpts_new_index(inode);
 685         tty_unlock();
 686         if (index < 0) {
 687                 retval = index;
 688                 goto err_file;
 689         }
 690
 691         mutex_lock(&tty_mutex);
 692         tty_lock();
 693         tty = tty_init_dev(ptm_driver, index, 1);
 694         mutex_unlock(&tty_mutex);
 695
 696         if (IS_ERR(tty)) {
 697                 retval = PTR_ERR(tty);
 698                 goto out;
 699         }
 700
 701         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 702
 703         tty_add_file(tty, filp);
 704
 705         retval = devpts_pty_new(inode, tty->link);
 706         if (retval)
 707                 goto err_release;
 708
 709         retval = ptm_driver->ops->open(tty, filp);
 710         if (retval)
 711                 goto err_release;
 712
 713         tty_unlock();
 714         return 0;
 715 err_release:
 716         tty_unlock();
 717         tty_release(inode, filp);
 718         return retval;
 719 out:
 720         devpts_kill_index(inode, index);
 721         tty_unlock();
 722 err_file:
 723         tty_free_file(filp);
 724         return retval;
 725 }
 726
 727 static struct file_operations ptmx_fops;
 728
 729 static void __init unix98_pty_init(void)
 730 {
 731         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 732         if (!ptm_driver)
 733                 panic("Couldn't allocate Unix98 ptm driver");
 734         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 735         if (!pts_driver)
 736                 panic("Couldn't allocate Unix98 pts driver");
 737
 738         ptm_driver->owner = THIS_MODULE;
 739         ptm_driver->driver_name = "pty_master";
 740         ptm_driver->name = "ptm";
 741         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 742         ptm_driver->minor_start = 0;
 743         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 744         ptm_driver->subtype = PTY_TYPE_MASTER;
 745         ptm_driver->init_termios = tty_std_termios;
 746         ptm_driver->init_termios.c_iflag = 0;
 747         ptm_driver->init_termios.c_oflag = 0;
 748         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 749         ptm_driver->init_termios.c_lflag = 0;
 750         ptm_driver->init_termios.c_ispeed = 38400;
 751         ptm_driver->init_termios.c_ospeed = 38400;
 752         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 753                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 754         ptm_driver->other = pts_driver;
 755         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 756
 757         pts_driver->owner = THIS_MODULE;
 758         pts_driver->driver_name = "pty_slave";
 759         pts_driver->name = "pts";
 760         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 761         pts_driver->minor_start = 0;
 762         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 763         pts_driver->subtype = PTY_TYPE_SLAVE;
 764         pts_driver->init_termios = tty_std_termios;
 765         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 766         pts_driver->init_termios.c_ispeed = 38400;
 767         pts_driver->init_termios.c_ospeed = 38400;
 768         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 769                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 770         pts_driver->other = ptm_driver;
 771         tty_set_operations(pts_driver, &pty_unix98_ops);
 772
 773         if (tty_register_driver(ptm_driver))
 774                 panic("Couldn't register Unix98 ptm driver");
 775         if (tty_register_driver(pts_driver))
 776                 panic("Couldn't register Unix98 pts driver");
 777
 778         register_sysctl_table(pty_root_table);
 779
 780         /* Now create the /dev/ptmx special device */
 781         tty_default_fops(&ptmx_fops);
 782         ptmx_fops.open = ptmx_open;
 783
 784         cdev_init(&ptmx_cdev, &ptmx_fops);
 785         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 786             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 787                 panic("Couldn't register /dev/ptmx driver\n");
 788         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 789 }
 790
 791 #else
 792 static inline void unix98_pty_init(void) { }
 793 #endif
 794
 795 static int __init pty_init(void)
 796 {
 797         legacy_pty_init();
 798         unix98_pty_init();
 799         return 0;
 800 }
 801 module_init(pty_init);