Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux...
[linux-2.6] / drivers / char / tty_io.c
1 /*
2  *  linux/drivers/char/tty_io.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 /*
8  * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
9  * or rs-channels. It also implements echoing, cooked mode etc.
10  *
11  * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
12  *
13  * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
14  * tty_struct and tty_queue structures.  Previously there was an array
15  * of 256 tty_struct's which was statically allocated, and the
16  * tty_queue structures were allocated at boot time.  Both are now
17  * dynamically allocated only when the tty is open.
18  *
19  * Also restructured routines so that there is more of a separation
20  * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
21  * the low-level tty routines (serial.c, pty.c, console.c).  This
22  * makes for cleaner and more compact code.  -TYT, 9/17/92
23  *
24  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
25  * which can be dynamically activated and de-activated by the line
26  * discipline handling modules (like SLIP).
27  *
28  * NOTE: pay no attention to the line discipline code (yet); its
29  * interface is still subject to change in this version...
30  * -- TYT, 1/31/92
31  *
32  * Added functionality to the OPOST tty handling.  No delays, but all
33  * other bits should be there.
34  *      -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
35  *
36  * Rewrote canonical mode and added more termios flags.
37  *      -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
38  *
39  * Reorganized FASYNC support so mouse code can share it.
40  *      -- ctm@ardi.com, 9Sep95
41  *
42  * New TIOCLINUX variants added.
43  *      -- mj@k332.feld.cvut.cz, 19-Nov-95
44  *
45  * Restrict vt switching via ioctl()
46  *      -- grif@cs.ucr.edu, 5-Dec-95
47  *
48  * Move console and virtual terminal code to more appropriate files,
49  * implement CONFIG_VT and generalize console device interface.
50  *      -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
51  *
52  * Rewrote tty_init_dev and tty_release_dev to eliminate races.
53  *      -- Bill Hawes <whawes@star.net>, June 97
54  *
55  * Added devfs support.
56  *      -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
57  *
58  * Added support for a Unix98-style ptmx device.
59  *      -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
60  *
61  * Reduced memory usage for older ARM systems
62  *      -- Russell King <rmk@arm.linux.org.uk>
63  *
64  * Move do_SAK() into process context.  Less stack use in devfs functions.
65  * alloc_tty_struct() always uses kmalloc()
66  *                       -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
67  */
68
69 #include <linux/types.h>
70 #include <linux/major.h>
71 #include <linux/errno.h>
72 #include <linux/signal.h>
73 #include <linux/fcntl.h>
74 #include <linux/sched.h>
75 #include <linux/interrupt.h>
76 #include <linux/tty.h>
77 #include <linux/tty_driver.h>
78 #include <linux/tty_flip.h>
79 #include <linux/devpts_fs.h>
80 #include <linux/file.h>
81 #include <linux/fdtable.h>
82 #include <linux/console.h>
83 #include <linux/timer.h>
84 #include <linux/ctype.h>
85 #include <linux/kd.h>
86 #include <linux/mm.h>
87 #include <linux/string.h>
88 #include <linux/slab.h>
89 #include <linux/poll.h>
90 #include <linux/proc_fs.h>
91 #include <linux/init.h>
92 #include <linux/module.h>
93 #include <linux/smp_lock.h>
94 #include <linux/device.h>
95 #include <linux/wait.h>
96 #include <linux/bitops.h>
97 #include <linux/delay.h>
98 #include <linux/seq_file.h>
99
100 #include <linux/uaccess.h>
101 #include <asm/system.h>
102
103 #include <linux/kbd_kern.h>
104 #include <linux/vt_kern.h>
105 #include <linux/selection.h>
106
107 #include <linux/kmod.h>
108 #include <linux/nsproxy.h>
109
110 #undef TTY_DEBUG_HANGUP
111
112 #define TTY_PARANOIA_CHECK 1
113 #define CHECK_TTY_COUNT 1
114
115 struct ktermios tty_std_termios = {     /* for the benefit of tty drivers  */
116         .c_iflag = ICRNL | IXON,
117         .c_oflag = OPOST | ONLCR,
118         .c_cflag = B38400 | CS8 | CREAD | HUPCL,
119         .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
120                    ECHOCTL | ECHOKE | IEXTEN,
121         .c_cc = INIT_C_CC,
122         .c_ispeed = 38400,
123         .c_ospeed = 38400
124 };
125
126 EXPORT_SYMBOL(tty_std_termios);
127
128 /* This list gets poked at by procfs and various bits of boot up code. This
129    could do with some rationalisation such as pulling the tty proc function
130    into this file */
131
132 LIST_HEAD(tty_drivers);                 /* linked list of tty drivers */
133
134 /* Mutex to protect creating and releasing a tty. This is shared with
135    vt.c for deeply disgusting hack reasons */
136 DEFINE_MUTEX(tty_mutex);
137 EXPORT_SYMBOL(tty_mutex);
138
139 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
140 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
141 ssize_t redirected_tty_write(struct file *, const char __user *,
142                                                         size_t, loff_t *);
143 static unsigned int tty_poll(struct file *, poll_table *);
144 static int tty_open(struct inode *, struct file *);
145 static int tty_release(struct inode *, struct file *);
146 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
147 #ifdef CONFIG_COMPAT
148 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
149                                 unsigned long arg);
150 #else
151 #define tty_compat_ioctl NULL
152 #endif
153 static int tty_fasync(int fd, struct file *filp, int on);
154 static void release_tty(struct tty_struct *tty, int idx);
155 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
156 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
157
158 /**
159  *      alloc_tty_struct        -       allocate a tty object
160  *
161  *      Return a new empty tty structure. The data fields have not
162  *      been initialized in any way but has been zeroed
163  *
164  *      Locking: none
165  */
166
167 struct tty_struct *alloc_tty_struct(void)
168 {
169         return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
170 }
171
172 /**
173  *      free_tty_struct         -       free a disused tty
174  *      @tty: tty struct to free
175  *
176  *      Free the write buffers, tty queue and tty memory itself.
177  *
178  *      Locking: none. Must be called after tty is definitely unused
179  */
180
181 void free_tty_struct(struct tty_struct *tty)
182 {
183         kfree(tty->write_buf);
184         tty_buffer_free_all(tty);
185         kfree(tty);
186 }
187
188 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
189
190 /**
191  *      tty_name        -       return tty naming
192  *      @tty: tty structure
193  *      @buf: buffer for output
194  *
195  *      Convert a tty structure into a name. The name reflects the kernel
196  *      naming policy and if udev is in use may not reflect user space
197  *
198  *      Locking: none
199  */
200
201 char *tty_name(struct tty_struct *tty, char *buf)
202 {
203         if (!tty) /* Hmm.  NULL pointer.  That's fun. */
204                 strcpy(buf, "NULL tty");
205         else
206                 strcpy(buf, tty->name);
207         return buf;
208 }
209
210 EXPORT_SYMBOL(tty_name);
211
212 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
213                               const char *routine)
214 {
215 #ifdef TTY_PARANOIA_CHECK
216         if (!tty) {
217                 printk(KERN_WARNING
218                         "null TTY for (%d:%d) in %s\n",
219                         imajor(inode), iminor(inode), routine);
220                 return 1;
221         }
222         if (tty->magic != TTY_MAGIC) {
223                 printk(KERN_WARNING
224                         "bad magic number for tty struct (%d:%d) in %s\n",
225                         imajor(inode), iminor(inode), routine);
226                 return 1;
227         }
228 #endif
229         return 0;
230 }
231
232 static int check_tty_count(struct tty_struct *tty, const char *routine)
233 {
234 #ifdef CHECK_TTY_COUNT
235         struct list_head *p;
236         int count = 0;
237
238         file_list_lock();
239         list_for_each(p, &tty->tty_files) {
240                 count++;
241         }
242         file_list_unlock();
243         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
244             tty->driver->subtype == PTY_TYPE_SLAVE &&
245             tty->link && tty->link->count)
246                 count++;
247         if (tty->count != count) {
248                 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
249                                     "!= #fd's(%d) in %s\n",
250                        tty->name, tty->count, count, routine);
251                 return count;
252         }
253 #endif
254         return 0;
255 }
256
257 /**
258  *      get_tty_driver          -       find device of a tty
259  *      @dev_t: device identifier
260  *      @index: returns the index of the tty
261  *
262  *      This routine returns a tty driver structure, given a device number
263  *      and also passes back the index number.
264  *
265  *      Locking: caller must hold tty_mutex
266  */
267
268 static struct tty_driver *get_tty_driver(dev_t device, int *index)
269 {
270         struct tty_driver *p;
271
272         list_for_each_entry(p, &tty_drivers, tty_drivers) {
273                 dev_t base = MKDEV(p->major, p->minor_start);
274                 if (device < base || device >= base + p->num)
275                         continue;
276                 *index = device - base;
277                 return tty_driver_kref_get(p);
278         }
279         return NULL;
280 }
281
282 #ifdef CONFIG_CONSOLE_POLL
283
284 /**
285  *      tty_find_polling_driver -       find device of a polled tty
286  *      @name: name string to match
287  *      @line: pointer to resulting tty line nr
288  *
289  *      This routine returns a tty driver structure, given a name
290  *      and the condition that the tty driver is capable of polled
291  *      operation.
292  */
293 struct tty_driver *tty_find_polling_driver(char *name, int *line)
294 {
295         struct tty_driver *p, *res = NULL;
296         int tty_line = 0;
297         int len;
298         char *str;
299
300         for (str = name; *str; str++)
301                 if ((*str >= '0' && *str <= '9') || *str == ',')
302                         break;
303         if (!*str)
304                 return NULL;
305
306         len = str - name;
307         tty_line = simple_strtoul(str, &str, 10);
308
309         mutex_lock(&tty_mutex);
310         /* Search through the tty devices to look for a match */
311         list_for_each_entry(p, &tty_drivers, tty_drivers) {
312                 if (strncmp(name, p->name, len) != 0)
313                         continue;
314                 if (*str == ',')
315                         str++;
316                 if (*str == '\0')
317                         str = NULL;
318
319                 if (tty_line >= 0 && tty_line <= p->num && p->ops &&
320                     p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
321                         res = tty_driver_kref_get(p);
322                         *line = tty_line;
323                         break;
324                 }
325         }
326         mutex_unlock(&tty_mutex);
327
328         return res;
329 }
330 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
331 #endif
332
333 /**
334  *      tty_check_change        -       check for POSIX terminal changes
335  *      @tty: tty to check
336  *
337  *      If we try to write to, or set the state of, a terminal and we're
338  *      not in the foreground, send a SIGTTOU.  If the signal is blocked or
339  *      ignored, go ahead and perform the operation.  (POSIX 7.2)
340  *
341  *      Locking: ctrl_lock
342  */
343
344 int tty_check_change(struct tty_struct *tty)
345 {
346         unsigned long flags;
347         int ret = 0;
348
349         if (current->signal->tty != tty)
350                 return 0;
351
352         spin_lock_irqsave(&tty->ctrl_lock, flags);
353
354         if (!tty->pgrp) {
355                 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
356                 goto out_unlock;
357         }
358         if (task_pgrp(current) == tty->pgrp)
359                 goto out_unlock;
360         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
361         if (is_ignored(SIGTTOU))
362                 goto out;
363         if (is_current_pgrp_orphaned()) {
364                 ret = -EIO;
365                 goto out;
366         }
367         kill_pgrp(task_pgrp(current), SIGTTOU, 1);
368         set_thread_flag(TIF_SIGPENDING);
369         ret = -ERESTARTSYS;
370 out:
371         return ret;
372 out_unlock:
373         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
374         return ret;
375 }
376
377 EXPORT_SYMBOL(tty_check_change);
378
379 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
380                                 size_t count, loff_t *ppos)
381 {
382         return 0;
383 }
384
385 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
386                                  size_t count, loff_t *ppos)
387 {
388         return -EIO;
389 }
390
391 /* No kernel lock held - none needed ;) */
392 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
393 {
394         return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
395 }
396
397 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
398                 unsigned long arg)
399 {
400         return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
401 }
402
403 static long hung_up_tty_compat_ioctl(struct file *file,
404                                      unsigned int cmd, unsigned long arg)
405 {
406         return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
407 }
408
409 static const struct file_operations tty_fops = {
410         .llseek         = no_llseek,
411         .read           = tty_read,
412         .write          = tty_write,
413         .poll           = tty_poll,
414         .unlocked_ioctl = tty_ioctl,
415         .compat_ioctl   = tty_compat_ioctl,
416         .open           = tty_open,
417         .release        = tty_release,
418         .fasync         = tty_fasync,
419 };
420
421 static const struct file_operations console_fops = {
422         .llseek         = no_llseek,
423         .read           = tty_read,
424         .write          = redirected_tty_write,
425         .poll           = tty_poll,
426         .unlocked_ioctl = tty_ioctl,
427         .compat_ioctl   = tty_compat_ioctl,
428         .open           = tty_open,
429         .release        = tty_release,
430         .fasync         = tty_fasync,
431 };
432
433 static const struct file_operations hung_up_tty_fops = {
434         .llseek         = no_llseek,
435         .read           = hung_up_tty_read,
436         .write          = hung_up_tty_write,
437         .poll           = hung_up_tty_poll,
438         .unlocked_ioctl = hung_up_tty_ioctl,
439         .compat_ioctl   = hung_up_tty_compat_ioctl,
440         .release        = tty_release,
441 };
442
443 static DEFINE_SPINLOCK(redirect_lock);
444 static struct file *redirect;
445
446 /**
447  *      tty_wakeup      -       request more data
448  *      @tty: terminal
449  *
450  *      Internal and external helper for wakeups of tty. This function
451  *      informs the line discipline if present that the driver is ready
452  *      to receive more output data.
453  */
454
455 void tty_wakeup(struct tty_struct *tty)
456 {
457         struct tty_ldisc *ld;
458
459         if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
460                 ld = tty_ldisc_ref(tty);
461                 if (ld) {
462                         if (ld->ops->write_wakeup)
463                                 ld->ops->write_wakeup(tty);
464                         tty_ldisc_deref(ld);
465                 }
466         }
467         wake_up_interruptible(&tty->write_wait);
468 }
469
470 EXPORT_SYMBOL_GPL(tty_wakeup);
471
472 /**
473  *      tty_ldisc_flush -       flush line discipline queue
474  *      @tty: tty
475  *
476  *      Flush the line discipline queue (if any) for this tty. If there
477  *      is no line discipline active this is a no-op.
478  */
479
480 void tty_ldisc_flush(struct tty_struct *tty)
481 {
482         struct tty_ldisc *ld = tty_ldisc_ref(tty);
483         if (ld) {
484                 if (ld->ops->flush_buffer)
485                         ld->ops->flush_buffer(tty);
486                 tty_ldisc_deref(ld);
487         }
488         tty_buffer_flush(tty);
489 }
490
491 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
492
493 /**
494  *      tty_reset_termios       -       reset terminal state
495  *      @tty: tty to reset
496  *
497  *      Restore a terminal to the driver default state
498  */
499
500 static void tty_reset_termios(struct tty_struct *tty)
501 {
502         mutex_lock(&tty->termios_mutex);
503         *tty->termios = tty->driver->init_termios;
504         tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
505         tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
506         mutex_unlock(&tty->termios_mutex);
507 }
508
509 /**
510  *      do_tty_hangup           -       actual handler for hangup events
511  *      @work: tty device
512  *
513  *      This can be called by the "eventd" kernel thread.  That is process
514  *      synchronous but doesn't hold any locks, so we need to make sure we
515  *      have the appropriate locks for what we're doing.
516  *
517  *      The hangup event clears any pending redirections onto the hung up
518  *      device. It ensures future writes will error and it does the needed
519  *      line discipline hangup and signal delivery. The tty object itself
520  *      remains intact.
521  *
522  *      Locking:
523  *              BKL
524  *                redirect lock for undoing redirection
525  *                file list lock for manipulating list of ttys
526  *                tty_ldisc_lock from called functions
527  *                termios_mutex resetting termios data
528  *                tasklist_lock to walk task list for hangup event
529  *                  ->siglock to protect ->signal/->sighand
530  */
531 static void do_tty_hangup(struct work_struct *work)
532 {
533         struct tty_struct *tty =
534                 container_of(work, struct tty_struct, hangup_work);
535         struct file *cons_filp = NULL;
536         struct file *filp, *f = NULL;
537         struct task_struct *p;
538         struct tty_ldisc *ld;
539         int    closecount = 0, n;
540         unsigned long flags;
541         int refs = 0;
542
543         if (!tty)
544                 return;
545
546         /* inuse_filps is protected by the single kernel lock */
547         lock_kernel();
548
549         spin_lock(&redirect_lock);
550         if (redirect && redirect->private_data == tty) {
551                 f = redirect;
552                 redirect = NULL;
553         }
554         spin_unlock(&redirect_lock);
555
556         check_tty_count(tty, "do_tty_hangup");
557         file_list_lock();
558         /* This breaks for file handles being sent over AF_UNIX sockets ? */
559         list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
560                 if (filp->f_op->write == redirected_tty_write)
561                         cons_filp = filp;
562                 if (filp->f_op->write != tty_write)
563                         continue;
564                 closecount++;
565                 tty_fasync(-1, filp, 0);        /* can't block */
566                 filp->f_op = &hung_up_tty_fops;
567         }
568         file_list_unlock();
569         /*
570          * FIXME! What are the locking issues here? This may me overdoing
571          * things... This question is especially important now that we've
572          * removed the irqlock.
573          */
574         ld = tty_ldisc_ref(tty);
575         if (ld != NULL) {
576                 /* We may have no line discipline at this point */
577                 if (ld->ops->flush_buffer)
578                         ld->ops->flush_buffer(tty);
579                 tty_driver_flush_buffer(tty);
580                 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
581                     ld->ops->write_wakeup)
582                         ld->ops->write_wakeup(tty);
583                 if (ld->ops->hangup)
584                         ld->ops->hangup(tty);
585         }
586         /*
587          * FIXME: Once we trust the LDISC code better we can wait here for
588          * ldisc completion and fix the driver call race
589          */
590         wake_up_interruptible(&tty->write_wait);
591         wake_up_interruptible(&tty->read_wait);
592         /*
593          * Shutdown the current line discipline, and reset it to
594          * N_TTY.
595          */
596         if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
597                 tty_reset_termios(tty);
598         /* Defer ldisc switch */
599         /* tty_deferred_ldisc_switch(N_TTY);
600
601           This should get done automatically when the port closes and
602           tty_release is called */
603
604         read_lock(&tasklist_lock);
605         if (tty->session) {
606                 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
607                         spin_lock_irq(&p->sighand->siglock);
608                         if (p->signal->tty == tty) {
609                                 p->signal->tty = NULL;
610                                 /* We defer the dereferences outside fo
611                                    the tasklist lock */
612                                 refs++;
613                         }
614                         if (!p->signal->leader) {
615                                 spin_unlock_irq(&p->sighand->siglock);
616                                 continue;
617                         }
618                         __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
619                         __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
620                         put_pid(p->signal->tty_old_pgrp);  /* A noop */
621                         spin_lock_irqsave(&tty->ctrl_lock, flags);
622                         if (tty->pgrp)
623                                 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
624                         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
625                         spin_unlock_irq(&p->sighand->siglock);
626                 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
627         }
628         read_unlock(&tasklist_lock);
629
630         spin_lock_irqsave(&tty->ctrl_lock, flags);
631         tty->flags = 0;
632         put_pid(tty->session);
633         put_pid(tty->pgrp);
634         tty->session = NULL;
635         tty->pgrp = NULL;
636         tty->ctrl_status = 0;
637         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
638
639         /* Account for the p->signal references we killed */
640         while (refs--)
641                 tty_kref_put(tty);
642
643         /*
644          * If one of the devices matches a console pointer, we
645          * cannot just call hangup() because that will cause
646          * tty->count and state->count to go out of sync.
647          * So we just call close() the right number of times.
648          */
649         if (cons_filp) {
650                 if (tty->ops->close)
651                         for (n = 0; n < closecount; n++)
652                                 tty->ops->close(tty, cons_filp);
653         } else if (tty->ops->hangup)
654                 (tty->ops->hangup)(tty);
655         /*
656          * We don't want to have driver/ldisc interactions beyond
657          * the ones we did here. The driver layer expects no
658          * calls after ->hangup() from the ldisc side. However we
659          * can't yet guarantee all that.
660          */
661         set_bit(TTY_HUPPED, &tty->flags);
662         if (ld) {
663                 tty_ldisc_enable(tty);
664                 tty_ldisc_deref(ld);
665         }
666         unlock_kernel();
667         if (f)
668                 fput(f);
669 }
670
671 /**
672  *      tty_hangup              -       trigger a hangup event
673  *      @tty: tty to hangup
674  *
675  *      A carrier loss (virtual or otherwise) has occurred on this like
676  *      schedule a hangup sequence to run after this event.
677  */
678
679 void tty_hangup(struct tty_struct *tty)
680 {
681 #ifdef TTY_DEBUG_HANGUP
682         char    buf[64];
683         printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
684 #endif
685         schedule_work(&tty->hangup_work);
686 }
687
688 EXPORT_SYMBOL(tty_hangup);
689
690 /**
691  *      tty_vhangup             -       process vhangup
692  *      @tty: tty to hangup
693  *
694  *      The user has asked via system call for the terminal to be hung up.
695  *      We do this synchronously so that when the syscall returns the process
696  *      is complete. That guarantee is necessary for security reasons.
697  */
698
699 void tty_vhangup(struct tty_struct *tty)
700 {
701 #ifdef TTY_DEBUG_HANGUP
702         char    buf[64];
703
704         printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
705 #endif
706         do_tty_hangup(&tty->hangup_work);
707 }
708
709 EXPORT_SYMBOL(tty_vhangup);
710
711 /**
712  *      tty_vhangup_self        -       process vhangup for own ctty
713  *
714  *      Perform a vhangup on the current controlling tty
715  */
716
717 void tty_vhangup_self(void)
718 {
719         struct tty_struct *tty;
720
721         tty = get_current_tty();
722         if (tty) {
723                 tty_vhangup(tty);
724                 tty_kref_put(tty);
725         }
726 }
727
728 /**
729  *      tty_hung_up_p           -       was tty hung up
730  *      @filp: file pointer of tty
731  *
732  *      Return true if the tty has been subject to a vhangup or a carrier
733  *      loss
734  */
735
736 int tty_hung_up_p(struct file *filp)
737 {
738         return (filp->f_op == &hung_up_tty_fops);
739 }
740
741 EXPORT_SYMBOL(tty_hung_up_p);
742
743 static void session_clear_tty(struct pid *session)
744 {
745         struct task_struct *p;
746         do_each_pid_task(session, PIDTYPE_SID, p) {
747                 proc_clear_tty(p);
748         } while_each_pid_task(session, PIDTYPE_SID, p);
749 }
750
751 /**
752  *      disassociate_ctty       -       disconnect controlling tty
753  *      @on_exit: true if exiting so need to "hang up" the session
754  *
755  *      This function is typically called only by the session leader, when
756  *      it wants to disassociate itself from its controlling tty.
757  *
758  *      It performs the following functions:
759  *      (1)  Sends a SIGHUP and SIGCONT to the foreground process group
760  *      (2)  Clears the tty from being controlling the session
761  *      (3)  Clears the controlling tty for all processes in the
762  *              session group.
763  *
764  *      The argument on_exit is set to 1 if called when a process is
765  *      exiting; it is 0 if called by the ioctl TIOCNOTTY.
766  *
767  *      Locking:
768  *              BKL is taken for hysterical raisins
769  *                tty_mutex is taken to protect tty
770  *                ->siglock is taken to protect ->signal/->sighand
771  *                tasklist_lock is taken to walk process list for sessions
772  *                  ->siglock is taken to protect ->signal/->sighand
773  */
774
775 void disassociate_ctty(int on_exit)
776 {
777         struct tty_struct *tty;
778         struct pid *tty_pgrp = NULL;
779
780
781         tty = get_current_tty();
782         if (tty) {
783                 tty_pgrp = get_pid(tty->pgrp);
784                 lock_kernel();
785                 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
786                         tty_vhangup(tty);
787                 unlock_kernel();
788                 tty_kref_put(tty);
789         } else if (on_exit) {
790                 struct pid *old_pgrp;
791                 spin_lock_irq(&current->sighand->siglock);
792                 old_pgrp = current->signal->tty_old_pgrp;
793                 current->signal->tty_old_pgrp = NULL;
794                 spin_unlock_irq(&current->sighand->siglock);
795                 if (old_pgrp) {
796                         kill_pgrp(old_pgrp, SIGHUP, on_exit);
797                         kill_pgrp(old_pgrp, SIGCONT, on_exit);
798                         put_pid(old_pgrp);
799                 }
800                 return;
801         }
802         if (tty_pgrp) {
803                 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
804                 if (!on_exit)
805                         kill_pgrp(tty_pgrp, SIGCONT, on_exit);
806                 put_pid(tty_pgrp);
807         }
808
809         spin_lock_irq(&current->sighand->siglock);
810         put_pid(current->signal->tty_old_pgrp);
811         current->signal->tty_old_pgrp = NULL;
812         spin_unlock_irq(&current->sighand->siglock);
813
814         tty = get_current_tty();
815         if (tty) {
816                 unsigned long flags;
817                 spin_lock_irqsave(&tty->ctrl_lock, flags);
818                 put_pid(tty->session);
819                 put_pid(tty->pgrp);
820                 tty->session = NULL;
821                 tty->pgrp = NULL;
822                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
823                 tty_kref_put(tty);
824         } else {
825 #ifdef TTY_DEBUG_HANGUP
826                 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
827                        " = NULL", tty);
828 #endif
829         }
830
831         /* Now clear signal->tty under the lock */
832         read_lock(&tasklist_lock);
833         session_clear_tty(task_session(current));
834         read_unlock(&tasklist_lock);
835 }
836
837 /**
838  *
839  *      no_tty  - Ensure the current process does not have a controlling tty
840  */
841 void no_tty(void)
842 {
843         struct task_struct *tsk = current;
844         lock_kernel();
845         if (tsk->signal->leader)
846                 disassociate_ctty(0);
847         unlock_kernel();
848         proc_clear_tty(tsk);
849 }
850
851
852 /**
853  *      stop_tty        -       propagate flow control
854  *      @tty: tty to stop
855  *
856  *      Perform flow control to the driver. For PTY/TTY pairs we
857  *      must also propagate the TIOCKPKT status. May be called
858  *      on an already stopped device and will not re-call the driver
859  *      method.
860  *
861  *      This functionality is used by both the line disciplines for
862  *      halting incoming flow and by the driver. It may therefore be
863  *      called from any context, may be under the tty atomic_write_lock
864  *      but not always.
865  *
866  *      Locking:
867  *              Uses the tty control lock internally
868  */
869
870 void stop_tty(struct tty_struct *tty)
871 {
872         unsigned long flags;
873         spin_lock_irqsave(&tty->ctrl_lock, flags);
874         if (tty->stopped) {
875                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
876                 return;
877         }
878         tty->stopped = 1;
879         if (tty->link && tty->link->packet) {
880                 tty->ctrl_status &= ~TIOCPKT_START;
881                 tty->ctrl_status |= TIOCPKT_STOP;
882                 wake_up_interruptible(&tty->link->read_wait);
883         }
884         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
885         if (tty->ops->stop)
886                 (tty->ops->stop)(tty);
887 }
888
889 EXPORT_SYMBOL(stop_tty);
890
891 /**
892  *      start_tty       -       propagate flow control
893  *      @tty: tty to start
894  *
895  *      Start a tty that has been stopped if at all possible. Perform
896  *      any necessary wakeups and propagate the TIOCPKT status. If this
897  *      is the tty was previous stopped and is being started then the
898  *      driver start method is invoked and the line discipline woken.
899  *
900  *      Locking:
901  *              ctrl_lock
902  */
903
904 void start_tty(struct tty_struct *tty)
905 {
906         unsigned long flags;
907         spin_lock_irqsave(&tty->ctrl_lock, flags);
908         if (!tty->stopped || tty->flow_stopped) {
909                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
910                 return;
911         }
912         tty->stopped = 0;
913         if (tty->link && tty->link->packet) {
914                 tty->ctrl_status &= ~TIOCPKT_STOP;
915                 tty->ctrl_status |= TIOCPKT_START;
916                 wake_up_interruptible(&tty->link->read_wait);
917         }
918         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
919         if (tty->ops->start)
920                 (tty->ops->start)(tty);
921         /* If we have a running line discipline it may need kicking */
922         tty_wakeup(tty);
923 }
924
925 EXPORT_SYMBOL(start_tty);
926
927 /**
928  *      tty_read        -       read method for tty device files
929  *      @file: pointer to tty file
930  *      @buf: user buffer
931  *      @count: size of user buffer
932  *      @ppos: unused
933  *
934  *      Perform the read system call function on this terminal device. Checks
935  *      for hung up devices before calling the line discipline method.
936  *
937  *      Locking:
938  *              Locks the line discipline internally while needed. Multiple
939  *      read calls may be outstanding in parallel.
940  */
941
942 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
943                         loff_t *ppos)
944 {
945         int i;
946         struct tty_struct *tty;
947         struct inode *inode;
948         struct tty_ldisc *ld;
949
950         tty = (struct tty_struct *)file->private_data;
951         inode = file->f_path.dentry->d_inode;
952         if (tty_paranoia_check(tty, inode, "tty_read"))
953                 return -EIO;
954         if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
955                 return -EIO;
956
957         /* We want to wait for the line discipline to sort out in this
958            situation */
959         ld = tty_ldisc_ref_wait(tty);
960         if (ld->ops->read)
961                 i = (ld->ops->read)(tty, file, buf, count);
962         else
963                 i = -EIO;
964         tty_ldisc_deref(ld);
965         if (i > 0)
966                 inode->i_atime = current_fs_time(inode->i_sb);
967         return i;
968 }
969
970 void tty_write_unlock(struct tty_struct *tty)
971 {
972         mutex_unlock(&tty->atomic_write_lock);
973         wake_up_interruptible(&tty->write_wait);
974 }
975
976 int tty_write_lock(struct tty_struct *tty, int ndelay)
977 {
978         if (!mutex_trylock(&tty->atomic_write_lock)) {
979                 if (ndelay)
980                         return -EAGAIN;
981                 if (mutex_lock_interruptible(&tty->atomic_write_lock))
982                         return -ERESTARTSYS;
983         }
984         return 0;
985 }
986
987 /*
988  * Split writes up in sane blocksizes to avoid
989  * denial-of-service type attacks
990  */
991 static inline ssize_t do_tty_write(
992         ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
993         struct tty_struct *tty,
994         struct file *file,
995         const char __user *buf,
996         size_t count)
997 {
998         ssize_t ret, written = 0;
999         unsigned int chunk;
1000
1001         ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1002         if (ret < 0)
1003                 return ret;
1004
1005         /*
1006          * We chunk up writes into a temporary buffer. This
1007          * simplifies low-level drivers immensely, since they
1008          * don't have locking issues and user mode accesses.
1009          *
1010          * But if TTY_NO_WRITE_SPLIT is set, we should use a
1011          * big chunk-size..
1012          *
1013          * The default chunk-size is 2kB, because the NTTY
1014          * layer has problems with bigger chunks. It will
1015          * claim to be able to handle more characters than
1016          * it actually does.
1017          *
1018          * FIXME: This can probably go away now except that 64K chunks
1019          * are too likely to fail unless switched to vmalloc...
1020          */
1021         chunk = 2048;
1022         if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1023                 chunk = 65536;
1024         if (count < chunk)
1025                 chunk = count;
1026
1027         /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1028         if (tty->write_cnt < chunk) {
1029                 unsigned char *buf_chunk;
1030
1031                 if (chunk < 1024)
1032                         chunk = 1024;
1033
1034                 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1035                 if (!buf_chunk) {
1036                         ret = -ENOMEM;
1037                         goto out;
1038                 }
1039                 kfree(tty->write_buf);
1040                 tty->write_cnt = chunk;
1041                 tty->write_buf = buf_chunk;
1042         }
1043
1044         /* Do the write .. */
1045         for (;;) {
1046                 size_t size = count;
1047                 if (size > chunk)
1048                         size = chunk;
1049                 ret = -EFAULT;
1050                 if (copy_from_user(tty->write_buf, buf, size))
1051                         break;
1052                 ret = write(tty, file, tty->write_buf, size);
1053                 if (ret <= 0)
1054                         break;
1055                 written += ret;
1056                 buf += ret;
1057                 count -= ret;
1058                 if (!count)
1059                         break;
1060                 ret = -ERESTARTSYS;
1061                 if (signal_pending(current))
1062                         break;
1063                 cond_resched();
1064         }
1065         if (written) {
1066                 struct inode *inode = file->f_path.dentry->d_inode;
1067                 inode->i_mtime = current_fs_time(inode->i_sb);
1068                 ret = written;
1069         }
1070 out:
1071         tty_write_unlock(tty);
1072         return ret;
1073 }
1074
1075 /**
1076  * tty_write_message - write a message to a certain tty, not just the console.
1077  * @tty: the destination tty_struct
1078  * @msg: the message to write
1079  *
1080  * This is used for messages that need to be redirected to a specific tty.
1081  * We don't put it into the syslog queue right now maybe in the future if
1082  * really needed.
1083  *
1084  * We must still hold the BKL and test the CLOSING flag for the moment.
1085  */
1086
1087 void tty_write_message(struct tty_struct *tty, char *msg)
1088 {
1089         lock_kernel();
1090         if (tty) {
1091                 mutex_lock(&tty->atomic_write_lock);
1092                 if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags))
1093                         tty->ops->write(tty, msg, strlen(msg));
1094                 tty_write_unlock(tty);
1095         }
1096         unlock_kernel();
1097         return;
1098 }
1099
1100
1101 /**
1102  *      tty_write               -       write method for tty device file
1103  *      @file: tty file pointer
1104  *      @buf: user data to write
1105  *      @count: bytes to write
1106  *      @ppos: unused
1107  *
1108  *      Write data to a tty device via the line discipline.
1109  *
1110  *      Locking:
1111  *              Locks the line discipline as required
1112  *              Writes to the tty driver are serialized by the atomic_write_lock
1113  *      and are then processed in chunks to the device. The line discipline
1114  *      write method will not be involked in parallel for each device
1115  *              The line discipline write method is called under the big
1116  *      kernel lock for historical reasons. New code should not rely on this.
1117  */
1118
1119 static ssize_t tty_write(struct file *file, const char __user *buf,
1120                                                 size_t count, loff_t *ppos)
1121 {
1122         struct tty_struct *tty;
1123         struct inode *inode = file->f_path.dentry->d_inode;
1124         ssize_t ret;
1125         struct tty_ldisc *ld;
1126
1127         tty = (struct tty_struct *)file->private_data;
1128         if (tty_paranoia_check(tty, inode, "tty_write"))
1129                 return -EIO;
1130         if (!tty || !tty->ops->write ||
1131                 (test_bit(TTY_IO_ERROR, &tty->flags)))
1132                         return -EIO;
1133         /* Short term debug to catch buggy drivers */
1134         if (tty->ops->write_room == NULL)
1135                 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1136                         tty->driver->name);
1137         ld = tty_ldisc_ref_wait(tty);
1138         if (!ld->ops->write)
1139                 ret = -EIO;
1140         else
1141                 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1142         tty_ldisc_deref(ld);
1143         return ret;
1144 }
1145
1146 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1147                                                 size_t count, loff_t *ppos)
1148 {
1149         struct file *p = NULL;
1150
1151         spin_lock(&redirect_lock);
1152         if (redirect) {
1153                 get_file(redirect);
1154                 p = redirect;
1155         }
1156         spin_unlock(&redirect_lock);
1157
1158         if (p) {
1159                 ssize_t res;
1160                 res = vfs_write(p, buf, count, &p->f_pos);
1161                 fput(p);
1162                 return res;
1163         }
1164         return tty_write(file, buf, count, ppos);
1165 }
1166
1167 static char ptychar[] = "pqrstuvwxyzabcde";
1168
1169 /**
1170  *      pty_line_name   -       generate name for a pty
1171  *      @driver: the tty driver in use
1172  *      @index: the minor number
1173  *      @p: output buffer of at least 6 bytes
1174  *
1175  *      Generate a name from a driver reference and write it to the output
1176  *      buffer.
1177  *
1178  *      Locking: None
1179  */
1180 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1181 {
1182         int i = index + driver->name_base;
1183         /* ->name is initialized to "ttyp", but "tty" is expected */
1184         sprintf(p, "%s%c%x",
1185                 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1186                 ptychar[i >> 4 & 0xf], i & 0xf);
1187 }
1188
1189 /**
1190  *      tty_line_name   -       generate name for a tty
1191  *      @driver: the tty driver in use
1192  *      @index: the minor number
1193  *      @p: output buffer of at least 7 bytes
1194  *
1195  *      Generate a name from a driver reference and write it to the output
1196  *      buffer.
1197  *
1198  *      Locking: None
1199  */
1200 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1201 {
1202         sprintf(p, "%s%d", driver->name, index + driver->name_base);
1203 }
1204
1205 /**
1206  *      tty_driver_lookup_tty() - find an existing tty, if any
1207  *      @driver: the driver for the tty
1208  *      @idx:    the minor number
1209  *
1210  *      Return the tty, if found or ERR_PTR() otherwise.
1211  *
1212  *      Locking: tty_mutex must be held. If tty is found, the mutex must
1213  *      be held until the 'fast-open' is also done. Will change once we
1214  *      have refcounting in the driver and per driver locking
1215  */
1216 struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1217                 struct inode *inode, int idx)
1218 {
1219         struct tty_struct *tty;
1220
1221         if (driver->ops->lookup)
1222                 return driver->ops->lookup(driver, inode, idx);
1223
1224         tty = driver->ttys[idx];
1225         return tty;
1226 }
1227
1228 /**
1229  *      tty_init_termios        -  helper for termios setup
1230  *      @tty: the tty to set up
1231  *
1232  *      Initialise the termios structures for this tty. Thus runs under
1233  *      the tty_mutex currently so we can be relaxed about ordering.
1234  */
1235
1236 int tty_init_termios(struct tty_struct *tty)
1237 {
1238         struct ktermios *tp;
1239         int idx = tty->index;
1240
1241         tp = tty->driver->termios[idx];
1242         if (tp == NULL) {
1243                 tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
1244                 if (tp == NULL)
1245                         return -ENOMEM;
1246                 memcpy(tp, &tty->driver->init_termios,
1247                                                 sizeof(struct ktermios));
1248                 tty->driver->termios[idx] = tp;
1249         }
1250         tty->termios = tp;
1251         tty->termios_locked = tp + 1;
1252
1253         /* Compatibility until drivers always set this */
1254         tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1255         tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1256         return 0;
1257 }
1258
1259 /**
1260  *      tty_driver_install_tty() - install a tty entry in the driver
1261  *      @driver: the driver for the tty
1262  *      @tty: the tty
1263  *
1264  *      Install a tty object into the driver tables. The tty->index field
1265  *      will be set by the time this is called. This method is responsible
1266  *      for ensuring any need additional structures are allocated and
1267  *      configured.
1268  *
1269  *      Locking: tty_mutex for now
1270  */
1271 static int tty_driver_install_tty(struct tty_driver *driver,
1272                                                 struct tty_struct *tty)
1273 {
1274         int idx = tty->index;
1275
1276         if (driver->ops->install)
1277                 return driver->ops->install(driver, tty);
1278
1279         if (tty_init_termios(tty) == 0) {
1280                 tty_driver_kref_get(driver);
1281                 tty->count++;
1282                 driver->ttys[idx] = tty;
1283                 return 0;
1284         }
1285         return -ENOMEM;
1286 }
1287
1288 /**
1289  *      tty_driver_remove_tty() - remove a tty from the driver tables
1290  *      @driver: the driver for the tty
1291  *      @idx:    the minor number
1292  *
1293  *      Remvoe a tty object from the driver tables. The tty->index field
1294  *      will be set by the time this is called.
1295  *
1296  *      Locking: tty_mutex for now
1297  */
1298 static void tty_driver_remove_tty(struct tty_driver *driver,
1299                                                 struct tty_struct *tty)
1300 {
1301         if (driver->ops->remove)
1302                 driver->ops->remove(driver, tty);
1303         else
1304                 driver->ttys[tty->index] = NULL;
1305 }
1306
1307 /*
1308  *      tty_reopen()    - fast re-open of an open tty
1309  *      @tty    - the tty to open
1310  *
1311  *      Return 0 on success, -errno on error.
1312  *
1313  *      Locking: tty_mutex must be held from the time the tty was found
1314  *               till this open completes.
1315  */
1316 static int tty_reopen(struct tty_struct *tty)
1317 {
1318         struct tty_driver *driver = tty->driver;
1319
1320         if (test_bit(TTY_CLOSING, &tty->flags))
1321                 return -EIO;
1322
1323         if (driver->type == TTY_DRIVER_TYPE_PTY &&
1324             driver->subtype == PTY_TYPE_MASTER) {
1325                 /*
1326                  * special case for PTY masters: only one open permitted,
1327                  * and the slave side open count is incremented as well.
1328                  */
1329                 if (tty->count)
1330                         return -EIO;
1331
1332                 tty->link->count++;
1333         }
1334         tty->count++;
1335         tty->driver = driver; /* N.B. why do this every time?? */
1336
1337         WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1338
1339         return 0;
1340 }
1341
1342 /**
1343  *      tty_init_dev            -       initialise a tty device
1344  *      @driver: tty driver we are opening a device on
1345  *      @idx: device index
1346  *      @ret_tty: returned tty structure
1347  *      @first_ok: ok to open a new device (used by ptmx)
1348  *
1349  *      Prepare a tty device. This may not be a "new" clean device but
1350  *      could also be an active device. The pty drivers require special
1351  *      handling because of this.
1352  *
1353  *      Locking:
1354  *              The function is called under the tty_mutex, which
1355  *      protects us from the tty struct or driver itself going away.
1356  *
1357  *      On exit the tty device has the line discipline attached and
1358  *      a reference count of 1. If a pair was created for pty/tty use
1359  *      and the other was a pty master then it too has a reference count of 1.
1360  *
1361  * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1362  * failed open.  The new code protects the open with a mutex, so it's
1363  * really quite straightforward.  The mutex locking can probably be
1364  * relaxed for the (most common) case of reopening a tty.
1365  */
1366
1367 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
1368                                                                 int first_ok)
1369 {
1370         struct tty_struct *tty;
1371         int retval;
1372
1373         /* Check if pty master is being opened multiple times */
1374         if (driver->subtype == PTY_TYPE_MASTER &&
1375                 (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok)
1376                 return ERR_PTR(-EIO);
1377
1378         /*
1379          * First time open is complex, especially for PTY devices.
1380          * This code guarantees that either everything succeeds and the
1381          * TTY is ready for operation, or else the table slots are vacated
1382          * and the allocated memory released.  (Except that the termios
1383          * and locked termios may be retained.)
1384          */
1385
1386         if (!try_module_get(driver->owner))
1387                 return ERR_PTR(-ENODEV);
1388
1389         tty = alloc_tty_struct();
1390         if (!tty)
1391                 goto fail_no_mem;
1392         initialize_tty_struct(tty, driver, idx);
1393
1394         retval = tty_driver_install_tty(driver, tty);
1395         if (retval < 0) {
1396                 free_tty_struct(tty);
1397                 module_put(driver->owner);
1398                 return ERR_PTR(retval);
1399         }
1400
1401         /*
1402          * Structures all installed ... call the ldisc open routines.
1403          * If we fail here just call release_tty to clean up.  No need
1404          * to decrement the use counts, as release_tty doesn't care.
1405          */
1406
1407         retval = tty_ldisc_setup(tty, tty->link);
1408         if (retval)
1409                 goto release_mem_out;
1410         return tty;
1411
1412 fail_no_mem:
1413         module_put(driver->owner);
1414         return ERR_PTR(-ENOMEM);
1415
1416         /* call the tty release_tty routine to clean out this slot */
1417 release_mem_out:
1418         if (printk_ratelimit())
1419                 printk(KERN_INFO "tty_init_dev: ldisc open failed, "
1420                                  "clearing slot %d\n", idx);
1421         release_tty(tty, idx);
1422         return ERR_PTR(retval);
1423 }
1424
1425 void tty_free_termios(struct tty_struct *tty)
1426 {
1427         struct ktermios *tp;
1428         int idx = tty->index;
1429         /* Kill this flag and push into drivers for locking etc */
1430         if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
1431                 /* FIXME: Locking on ->termios array */
1432                 tp = tty->termios;
1433                 tty->driver->termios[idx] = NULL;
1434                 kfree(tp);
1435         }
1436 }
1437 EXPORT_SYMBOL(tty_free_termios);
1438
1439 void tty_shutdown(struct tty_struct *tty)
1440 {
1441         tty_driver_remove_tty(tty->driver, tty);
1442         tty_free_termios(tty);
1443 }
1444 EXPORT_SYMBOL(tty_shutdown);
1445
1446 /**
1447  *      release_one_tty         -       release tty structure memory
1448  *      @kref: kref of tty we are obliterating
1449  *
1450  *      Releases memory associated with a tty structure, and clears out the
1451  *      driver table slots. This function is called when a device is no longer
1452  *      in use. It also gets called when setup of a device fails.
1453  *
1454  *      Locking:
1455  *              tty_mutex - sometimes only
1456  *              takes the file list lock internally when working on the list
1457  *      of ttys that the driver keeps.
1458  */
1459 static void release_one_tty(struct kref *kref)
1460 {
1461         struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1462         struct tty_driver *driver = tty->driver;
1463
1464         if (tty->ops->shutdown)
1465                 tty->ops->shutdown(tty);
1466         else
1467                 tty_shutdown(tty);
1468         tty->magic = 0;
1469         tty_driver_kref_put(driver);
1470         module_put(driver->owner);
1471
1472         file_list_lock();
1473         list_del_init(&tty->tty_files);
1474         file_list_unlock();
1475
1476         free_tty_struct(tty);
1477 }
1478
1479 /**
1480  *      tty_kref_put            -       release a tty kref
1481  *      @tty: tty device
1482  *
1483  *      Release a reference to a tty device and if need be let the kref
1484  *      layer destruct the object for us
1485  */
1486
1487 void tty_kref_put(struct tty_struct *tty)
1488 {
1489         if (tty)
1490                 kref_put(&tty->kref, release_one_tty);
1491 }
1492 EXPORT_SYMBOL(tty_kref_put);
1493
1494 /**
1495  *      release_tty             -       release tty structure memory
1496  *
1497  *      Release both @tty and a possible linked partner (think pty pair),
1498  *      and decrement the refcount of the backing module.
1499  *
1500  *      Locking:
1501  *              tty_mutex - sometimes only
1502  *              takes the file list lock internally when working on the list
1503  *      of ttys that the driver keeps.
1504  *              FIXME: should we require tty_mutex is held here ??
1505  *
1506  */
1507 static void release_tty(struct tty_struct *tty, int idx)
1508 {
1509         /* This should always be true but check for the moment */
1510         WARN_ON(tty->index != idx);
1511
1512         if (tty->link)
1513                 tty_kref_put(tty->link);
1514         tty_kref_put(tty);
1515 }
1516
1517 /*
1518  * Even releasing the tty structures is a tricky business.. We have
1519  * to be very careful that the structures are all released at the
1520  * same time, as interrupts might otherwise get the wrong pointers.
1521  *
1522  * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1523  * lead to double frees or releasing memory still in use.
1524  */
1525 void tty_release_dev(struct file *filp)
1526 {
1527         struct tty_struct *tty, *o_tty;
1528         int     pty_master, tty_closing, o_tty_closing, do_sleep;
1529         int     devpts;
1530         int     idx;
1531         char    buf[64];
1532         struct  inode *inode;
1533
1534         inode = filp->f_path.dentry->d_inode;
1535         tty = (struct tty_struct *)filp->private_data;
1536         if (tty_paranoia_check(tty, inode, "tty_release_dev"))
1537                 return;
1538
1539         check_tty_count(tty, "tty_release_dev");
1540
1541         tty_fasync(-1, filp, 0);
1542
1543         idx = tty->index;
1544         pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1545                       tty->driver->subtype == PTY_TYPE_MASTER);
1546         devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1547         o_tty = tty->link;
1548
1549 #ifdef TTY_PARANOIA_CHECK
1550         if (idx < 0 || idx >= tty->driver->num) {
1551                 printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
1552                                   "free (%s)\n", tty->name);
1553                 return;
1554         }
1555         if (!devpts) {
1556                 if (tty != tty->driver->ttys[idx]) {
1557                         printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
1558                                "for (%s)\n", idx, tty->name);
1559                         return;
1560                 }
1561                 if (tty->termios != tty->driver->termios[idx]) {
1562                         printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
1563                                "for (%s)\n",
1564                                idx, tty->name);
1565                         return;
1566                 }
1567         }
1568 #endif
1569
1570 #ifdef TTY_DEBUG_HANGUP
1571         printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
1572                tty_name(tty, buf), tty->count);
1573 #endif
1574
1575 #ifdef TTY_PARANOIA_CHECK
1576         if (tty->driver->other &&
1577              !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
1578                 if (o_tty != tty->driver->other->ttys[idx]) {
1579                         printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
1580                                           "not o_tty for (%s)\n",
1581                                idx, tty->name);
1582                         return;
1583                 }
1584                 if (o_tty->termios != tty->driver->other->termios[idx]) {
1585                         printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
1586                                           "not o_termios for (%s)\n",
1587                                idx, tty->name);
1588                         return;
1589                 }
1590                 if (o_tty->link != tty) {
1591                         printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
1592                         return;
1593                 }
1594         }
1595 #endif
1596         if (tty->ops->close)
1597                 tty->ops->close(tty, filp);
1598
1599         /*
1600          * Sanity check: if tty->count is going to zero, there shouldn't be
1601          * any waiters on tty->read_wait or tty->write_wait.  We test the
1602          * wait queues and kick everyone out _before_ actually starting to
1603          * close.  This ensures that we won't block while releasing the tty
1604          * structure.
1605          *
1606          * The test for the o_tty closing is necessary, since the master and
1607          * slave sides may close in any order.  If the slave side closes out
1608          * first, its count will be one, since the master side holds an open.
1609          * Thus this test wouldn't be triggered at the time the slave closes,
1610          * so we do it now.
1611          *
1612          * Note that it's possible for the tty to be opened again while we're
1613          * flushing out waiters.  By recalculating the closing flags before
1614          * each iteration we avoid any problems.
1615          */
1616         while (1) {
1617                 /* Guard against races with tty->count changes elsewhere and
1618                    opens on /dev/tty */
1619
1620                 mutex_lock(&tty_mutex);
1621                 tty_closing = tty->count <= 1;
1622                 o_tty_closing = o_tty &&
1623                         (o_tty->count <= (pty_master ? 1 : 0));
1624                 do_sleep = 0;
1625
1626                 if (tty_closing) {
1627                         if (waitqueue_active(&tty->read_wait)) {
1628                                 wake_up(&tty->read_wait);
1629                                 do_sleep++;
1630                         }
1631                         if (waitqueue_active(&tty->write_wait)) {
1632                                 wake_up(&tty->write_wait);
1633                                 do_sleep++;
1634                         }
1635                 }
1636                 if (o_tty_closing) {
1637                         if (waitqueue_active(&o_tty->read_wait)) {
1638                                 wake_up(&o_tty->read_wait);
1639                                 do_sleep++;
1640                         }
1641                         if (waitqueue_active(&o_tty->write_wait)) {
1642                                 wake_up(&o_tty->write_wait);
1643                                 do_sleep++;
1644                         }
1645                 }
1646                 if (!do_sleep)
1647                         break;
1648
1649                 printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
1650                                     "active!\n", tty_name(tty, buf));
1651                 mutex_unlock(&tty_mutex);
1652                 schedule();
1653         }
1654
1655         /*
1656          * The closing flags are now consistent with the open counts on
1657          * both sides, and we've completed the last operation that could
1658          * block, so it's safe to proceed with closing.
1659          */
1660         if (pty_master) {
1661                 if (--o_tty->count < 0) {
1662                         printk(KERN_WARNING "tty_release_dev: bad pty slave count "
1663                                             "(%d) for %s\n",
1664                                o_tty->count, tty_name(o_tty, buf));
1665                         o_tty->count = 0;
1666                 }
1667         }
1668         if (--tty->count < 0) {
1669                 printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
1670                        tty->count, tty_name(tty, buf));
1671                 tty->count = 0;
1672         }
1673
1674         /*
1675          * We've decremented tty->count, so we need to remove this file
1676          * descriptor off the tty->tty_files list; this serves two
1677          * purposes:
1678          *  - check_tty_count sees the correct number of file descriptors
1679          *    associated with this tty.
1680          *  - do_tty_hangup no longer sees this file descriptor as
1681          *    something that needs to be handled for hangups.
1682          */
1683         file_kill(filp);
1684         filp->private_data = NULL;
1685
1686         /*
1687          * Perform some housekeeping before deciding whether to return.
1688          *
1689          * Set the TTY_CLOSING flag if this was the last open.  In the
1690          * case of a pty we may have to wait around for the other side
1691          * to close, and TTY_CLOSING makes sure we can't be reopened.
1692          */
1693         if (tty_closing)
1694                 set_bit(TTY_CLOSING, &tty->flags);
1695         if (o_tty_closing)
1696                 set_bit(TTY_CLOSING, &o_tty->flags);
1697
1698         /*
1699          * If _either_ side is closing, make sure there aren't any
1700          * processes that still think tty or o_tty is their controlling
1701          * tty.
1702          */
1703         if (tty_closing || o_tty_closing) {
1704                 read_lock(&tasklist_lock);
1705                 session_clear_tty(tty->session);
1706                 if (o_tty)
1707                         session_clear_tty(o_tty->session);
1708                 read_unlock(&tasklist_lock);
1709         }
1710
1711         mutex_unlock(&tty_mutex);
1712
1713         /* check whether both sides are closing ... */
1714         if (!tty_closing || (o_tty && !o_tty_closing))
1715                 return;
1716
1717 #ifdef TTY_DEBUG_HANGUP
1718         printk(KERN_DEBUG "freeing tty structure...");
1719 #endif
1720         /*
1721          * Ask the line discipline code to release its structures
1722          */
1723         tty_ldisc_release(tty, o_tty);
1724         /*
1725          * The release_tty function takes care of the details of clearing
1726          * the slots and preserving the termios structure.
1727          */
1728         release_tty(tty, idx);
1729
1730         /* Make this pty number available for reallocation */
1731         if (devpts)
1732                 devpts_kill_index(inode, idx);
1733 }
1734
1735 /**
1736  *      __tty_open              -       open a tty device
1737  *      @inode: inode of device file
1738  *      @filp: file pointer to tty
1739  *
1740  *      tty_open and tty_release keep up the tty count that contains the
1741  *      number of opens done on a tty. We cannot use the inode-count, as
1742  *      different inodes might point to the same tty.
1743  *
1744  *      Open-counting is needed for pty masters, as well as for keeping
1745  *      track of serial lines: DTR is dropped when the last close happens.
1746  *      (This is not done solely through tty->count, now.  - Ted 1/27/92)
1747  *
1748  *      The termios state of a pty is reset on first open so that
1749  *      settings don't persist across reuse.
1750  *
1751  *      Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
1752  *               tty->count should protect the rest.
1753  *               ->siglock protects ->signal/->sighand
1754  */
1755
1756 static int __tty_open(struct inode *inode, struct file *filp)
1757 {
1758         struct tty_struct *tty = NULL;
1759         int noctty, retval;
1760         struct tty_driver *driver;
1761         int index;
1762         dev_t device = inode->i_rdev;
1763         unsigned short saved_flags = filp->f_flags;
1764
1765         nonseekable_open(inode, filp);
1766
1767 retry_open:
1768         noctty = filp->f_flags & O_NOCTTY;
1769         index  = -1;
1770         retval = 0;
1771
1772         mutex_lock(&tty_mutex);
1773
1774         if (device == MKDEV(TTYAUX_MAJOR, 0)) {
1775                 tty = get_current_tty();
1776                 if (!tty) {
1777                         mutex_unlock(&tty_mutex);
1778                         return -ENXIO;
1779                 }
1780                 driver = tty_driver_kref_get(tty->driver);
1781                 index = tty->index;
1782                 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1783                 /* noctty = 1; */
1784                 /* FIXME: Should we take a driver reference ? */
1785                 tty_kref_put(tty);
1786                 goto got_driver;
1787         }
1788 #ifdef CONFIG_VT
1789         if (device == MKDEV(TTY_MAJOR, 0)) {
1790                 extern struct tty_driver *console_driver;
1791                 driver = tty_driver_kref_get(console_driver);
1792                 index = fg_console;
1793                 noctty = 1;
1794                 goto got_driver;
1795         }
1796 #endif
1797         if (device == MKDEV(TTYAUX_MAJOR, 1)) {
1798                 struct tty_driver *console_driver = console_device(&index);
1799                 if (console_driver) {
1800                         driver = tty_driver_kref_get(console_driver);
1801                         if (driver) {
1802                                 /* Don't let /dev/console block */
1803                                 filp->f_flags |= O_NONBLOCK;
1804                                 noctty = 1;
1805                                 goto got_driver;
1806                         }
1807                 }
1808                 mutex_unlock(&tty_mutex);
1809                 return -ENODEV;
1810         }
1811
1812         driver = get_tty_driver(device, &index);
1813         if (!driver) {
1814                 mutex_unlock(&tty_mutex);
1815                 return -ENODEV;
1816         }
1817 got_driver:
1818         if (!tty) {
1819                 /* check whether we're reopening an existing tty */
1820                 tty = tty_driver_lookup_tty(driver, inode, index);
1821
1822                 if (IS_ERR(tty))
1823                         return PTR_ERR(tty);
1824         }
1825
1826         if (tty) {
1827                 retval = tty_reopen(tty);
1828                 if (retval)
1829                         tty = ERR_PTR(retval);
1830         } else
1831                 tty = tty_init_dev(driver, index, 0);
1832
1833         mutex_unlock(&tty_mutex);
1834         tty_driver_kref_put(driver);
1835         if (IS_ERR(tty))
1836                 return PTR_ERR(tty);
1837
1838         filp->private_data = tty;
1839         file_move(filp, &tty->tty_files);
1840         check_tty_count(tty, "tty_open");
1841         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1842             tty->driver->subtype == PTY_TYPE_MASTER)
1843                 noctty = 1;
1844 #ifdef TTY_DEBUG_HANGUP
1845         printk(KERN_DEBUG "opening %s...", tty->name);
1846 #endif
1847         if (!retval) {
1848                 if (tty->ops->open)
1849                         retval = tty->ops->open(tty, filp);
1850                 else
1851                         retval = -ENODEV;
1852         }
1853         filp->f_flags = saved_flags;
1854
1855         if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
1856                                                 !capable(CAP_SYS_ADMIN))
1857                 retval = -EBUSY;
1858
1859         if (retval) {
1860 #ifdef TTY_DEBUG_HANGUP
1861                 printk(KERN_DEBUG "error %d in opening %s...", retval,
1862                        tty->name);
1863 #endif
1864                 tty_release_dev(filp);
1865                 if (retval != -ERESTARTSYS)
1866                         return retval;
1867                 if (signal_pending(current))
1868                         return retval;
1869                 schedule();
1870                 /*
1871                  * Need to reset f_op in case a hangup happened.
1872                  */
1873                 if (filp->f_op == &hung_up_tty_fops)
1874                         filp->f_op = &tty_fops;
1875                 goto retry_open;
1876         }
1877
1878         mutex_lock(&tty_mutex);
1879         spin_lock_irq(&current->sighand->siglock);
1880         if (!noctty &&
1881             current->signal->leader &&
1882             !current->signal->tty &&
1883             tty->session == NULL)
1884                 __proc_set_tty(current, tty);
1885         spin_unlock_irq(&current->sighand->siglock);
1886         mutex_unlock(&tty_mutex);
1887         return 0;
1888 }
1889
1890 /* BKL pushdown: scary code avoidance wrapper */
1891 static int tty_open(struct inode *inode, struct file *filp)
1892 {
1893         int ret;
1894
1895         lock_kernel();
1896         ret = __tty_open(inode, filp);
1897         unlock_kernel();
1898         return ret;
1899 }
1900
1901
1902
1903
1904 /**
1905  *      tty_release             -       vfs callback for close
1906  *      @inode: inode of tty
1907  *      @filp: file pointer for handle to tty
1908  *
1909  *      Called the last time each file handle is closed that references
1910  *      this tty. There may however be several such references.
1911  *
1912  *      Locking:
1913  *              Takes bkl. See tty_release_dev
1914  */
1915
1916 static int tty_release(struct inode *inode, struct file *filp)
1917 {
1918         lock_kernel();
1919         tty_release_dev(filp);
1920         unlock_kernel();
1921         return 0;
1922 }
1923
1924 /**
1925  *      tty_poll        -       check tty status
1926  *      @filp: file being polled
1927  *      @wait: poll wait structures to update
1928  *
1929  *      Call the line discipline polling method to obtain the poll
1930  *      status of the device.
1931  *
1932  *      Locking: locks called line discipline but ldisc poll method
1933  *      may be re-entered freely by other callers.
1934  */
1935
1936 static unsigned int tty_poll(struct file *filp, poll_table *wait)
1937 {
1938         struct tty_struct *tty;
1939         struct tty_ldisc *ld;
1940         int ret = 0;
1941
1942         tty = (struct tty_struct *)filp->private_data;
1943         if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
1944                 return 0;
1945
1946         ld = tty_ldisc_ref_wait(tty);
1947         if (ld->ops->poll)
1948                 ret = (ld->ops->poll)(tty, filp, wait);
1949         tty_ldisc_deref(ld);
1950         return ret;
1951 }
1952
1953 static int tty_fasync(int fd, struct file *filp, int on)
1954 {
1955         struct tty_struct *tty;
1956         unsigned long flags;
1957         int retval = 0;
1958
1959         lock_kernel();
1960         tty = (struct tty_struct *)filp->private_data;
1961         if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
1962                 goto out;
1963
1964         retval = fasync_helper(fd, filp, on, &tty->fasync);
1965         if (retval <= 0)
1966                 goto out;
1967
1968         if (on) {
1969                 enum pid_type type;
1970                 struct pid *pid;
1971                 if (!waitqueue_active(&tty->read_wait))
1972                         tty->minimum_to_wake = 1;
1973                 spin_lock_irqsave(&tty->ctrl_lock, flags);
1974                 if (tty->pgrp) {
1975                         pid = tty->pgrp;
1976                         type = PIDTYPE_PGID;
1977                 } else {
1978                         pid = task_pid(current);
1979                         type = PIDTYPE_PID;
1980                 }
1981                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1982                 retval = __f_setown(filp, pid, type, 0);
1983                 if (retval)
1984                         goto out;
1985         } else {
1986                 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
1987                         tty->minimum_to_wake = N_TTY_BUF_SIZE;
1988         }
1989         retval = 0;
1990 out:
1991         unlock_kernel();
1992         return retval;
1993 }
1994
1995 /**
1996  *      tiocsti                 -       fake input character
1997  *      @tty: tty to fake input into
1998  *      @p: pointer to character
1999  *
2000  *      Fake input to a tty device. Does the necessary locking and
2001  *      input management.
2002  *
2003  *      FIXME: does not honour flow control ??
2004  *
2005  *      Locking:
2006  *              Called functions take tty_ldisc_lock
2007  *              current->signal->tty check is safe without locks
2008  *
2009  *      FIXME: may race normal receive processing
2010  */
2011
2012 static int tiocsti(struct tty_struct *tty, char __user *p)
2013 {
2014         char ch, mbz = 0;
2015         struct tty_ldisc *ld;
2016
2017         if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2018                 return -EPERM;
2019         if (get_user(ch, p))
2020                 return -EFAULT;
2021         tty_audit_tiocsti(tty, ch);
2022         ld = tty_ldisc_ref_wait(tty);
2023         ld->ops->receive_buf(tty, &ch, &mbz, 1);
2024         tty_ldisc_deref(ld);
2025         return 0;
2026 }
2027
2028 /**
2029  *      tiocgwinsz              -       implement window query ioctl
2030  *      @tty; tty
2031  *      @arg: user buffer for result
2032  *
2033  *      Copies the kernel idea of the window size into the user buffer.
2034  *
2035  *      Locking: tty->termios_mutex is taken to ensure the winsize data
2036  *              is consistent.
2037  */
2038
2039 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2040 {
2041         int err;
2042
2043         mutex_lock(&tty->termios_mutex);
2044         err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2045         mutex_unlock(&tty->termios_mutex);
2046
2047         return err ? -EFAULT: 0;
2048 }
2049
2050 /**
2051  *      tty_do_resize           -       resize event
2052  *      @tty: tty being resized
2053  *      @real_tty: real tty (not the same as tty if using a pty/tty pair)
2054  *      @rows: rows (character)
2055  *      @cols: cols (character)
2056  *
2057  *      Update the termios variables and send the neccessary signals to
2058  *      peform a terminal resize correctly
2059  */
2060
2061 int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
2062                                         struct winsize *ws)
2063 {
2064         struct pid *pgrp, *rpgrp;
2065         unsigned long flags;
2066
2067         /* For a PTY we need to lock the tty side */
2068         mutex_lock(&real_tty->termios_mutex);
2069         if (!memcmp(ws, &real_tty->winsize, sizeof(*ws)))
2070                 goto done;
2071         /* Get the PID values and reference them so we can
2072            avoid holding the tty ctrl lock while sending signals */
2073         spin_lock_irqsave(&tty->ctrl_lock, flags);
2074         pgrp = get_pid(tty->pgrp);
2075         rpgrp = get_pid(real_tty->pgrp);
2076         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2077
2078         if (pgrp)
2079                 kill_pgrp(pgrp, SIGWINCH, 1);
2080         if (rpgrp != pgrp && rpgrp)
2081                 kill_pgrp(rpgrp, SIGWINCH, 1);
2082
2083         put_pid(pgrp);
2084         put_pid(rpgrp);
2085
2086         tty->winsize = *ws;
2087         real_tty->winsize = *ws;
2088 done:
2089         mutex_unlock(&real_tty->termios_mutex);
2090         return 0;
2091 }
2092
2093 /**
2094  *      tiocswinsz              -       implement window size set ioctl
2095  *      @tty; tty
2096  *      @arg: user buffer for result
2097  *
2098  *      Copies the user idea of the window size to the kernel. Traditionally
2099  *      this is just advisory information but for the Linux console it
2100  *      actually has driver level meaning and triggers a VC resize.
2101  *
2102  *      Locking:
2103  *              Driver dependant. The default do_resize method takes the
2104  *      tty termios mutex and ctrl_lock. The console takes its own lock
2105  *      then calls into the default method.
2106  */
2107
2108 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
2109         struct winsize __user *arg)
2110 {
2111         struct winsize tmp_ws;
2112         if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2113                 return -EFAULT;
2114
2115         if (tty->ops->resize)
2116                 return tty->ops->resize(tty, real_tty, &tmp_ws);
2117         else
2118                 return tty_do_resize(tty, real_tty, &tmp_ws);
2119 }
2120
2121 /**
2122  *      tioccons        -       allow admin to move logical console
2123  *      @file: the file to become console
2124  *
2125  *      Allow the adminstrator to move the redirected console device
2126  *
2127  *      Locking: uses redirect_lock to guard the redirect information
2128  */
2129
2130 static int tioccons(struct file *file)
2131 {
2132         if (!capable(CAP_SYS_ADMIN))
2133                 return -EPERM;
2134         if (file->f_op->write == redirected_tty_write) {
2135                 struct file *f;
2136                 spin_lock(&redirect_lock);
2137                 f = redirect;
2138                 redirect = NULL;
2139                 spin_unlock(&redirect_lock);
2140                 if (f)
2141                         fput(f);
2142                 return 0;
2143         }
2144         spin_lock(&redirect_lock);
2145         if (redirect) {
2146                 spin_unlock(&redirect_lock);
2147                 return -EBUSY;
2148         }
2149         get_file(file);
2150         redirect = file;
2151         spin_unlock(&redirect_lock);
2152         return 0;
2153 }
2154
2155 /**
2156  *      fionbio         -       non blocking ioctl
2157  *      @file: file to set blocking value
2158  *      @p: user parameter
2159  *
2160  *      Historical tty interfaces had a blocking control ioctl before
2161  *      the generic functionality existed. This piece of history is preserved
2162  *      in the expected tty API of posix OS's.
2163  *
2164  *      Locking: none, the open fle handle ensures it won't go away.
2165  */
2166
2167 static int fionbio(struct file *file, int __user *p)
2168 {
2169         int nonblock;
2170
2171         if (get_user(nonblock, p))
2172                 return -EFAULT;
2173
2174         /* file->f_flags is still BKL protected in the fs layer - vomit */
2175         lock_kernel();
2176         if (nonblock)
2177                 file->f_flags |= O_NONBLOCK;
2178         else
2179                 file->f_flags &= ~O_NONBLOCK;
2180         unlock_kernel();
2181         return 0;
2182 }
2183
2184 /**
2185  *      tiocsctty       -       set controlling tty
2186  *      @tty: tty structure
2187  *      @arg: user argument
2188  *
2189  *      This ioctl is used to manage job control. It permits a session
2190  *      leader to set this tty as the controlling tty for the session.
2191  *
2192  *      Locking:
2193  *              Takes tty_mutex() to protect tty instance
2194  *              Takes tasklist_lock internally to walk sessions
2195  *              Takes ->siglock() when updating signal->tty
2196  */
2197
2198 static int tiocsctty(struct tty_struct *tty, int arg)
2199 {
2200         int ret = 0;
2201         if (current->signal->leader && (task_session(current) == tty->session))
2202                 return ret;
2203
2204         mutex_lock(&tty_mutex);
2205         /*
2206          * The process must be a session leader and
2207          * not have a controlling tty already.
2208          */
2209         if (!current->signal->leader || current->signal->tty) {
2210                 ret = -EPERM;
2211                 goto unlock;
2212         }
2213
2214         if (tty->session) {
2215                 /*
2216                  * This tty is already the controlling
2217                  * tty for another session group!
2218                  */
2219                 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2220                         /*
2221                          * Steal it away
2222                          */
2223                         read_lock(&tasklist_lock);
2224                         session_clear_tty(tty->session);
2225                         read_unlock(&tasklist_lock);
2226                 } else {
2227                         ret = -EPERM;
2228                         goto unlock;
2229                 }
2230         }
2231         proc_set_tty(current, tty);
2232 unlock:
2233         mutex_unlock(&tty_mutex);
2234         return ret;
2235 }
2236
2237 /**
2238  *      tty_get_pgrp    -       return a ref counted pgrp pid
2239  *      @tty: tty to read
2240  *
2241  *      Returns a refcounted instance of the pid struct for the process
2242  *      group controlling the tty.
2243  */
2244
2245 struct pid *tty_get_pgrp(struct tty_struct *tty)
2246 {
2247         unsigned long flags;
2248         struct pid *pgrp;
2249
2250         spin_lock_irqsave(&tty->ctrl_lock, flags);
2251         pgrp = get_pid(tty->pgrp);
2252         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2253
2254         return pgrp;
2255 }
2256 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2257
2258 /**
2259  *      tiocgpgrp               -       get process group
2260  *      @tty: tty passed by user
2261  *      @real_tty: tty side of the tty pased by the user if a pty else the tty
2262  *      @p: returned pid
2263  *
2264  *      Obtain the process group of the tty. If there is no process group
2265  *      return an error.
2266  *
2267  *      Locking: none. Reference to current->signal->tty is safe.
2268  */
2269
2270 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2271 {
2272         struct pid *pid;
2273         int ret;
2274         /*
2275          * (tty == real_tty) is a cheap way of
2276          * testing if the tty is NOT a master pty.
2277          */
2278         if (tty == real_tty && current->signal->tty != real_tty)
2279                 return -ENOTTY;
2280         pid = tty_get_pgrp(real_tty);
2281         ret =  put_user(pid_vnr(pid), p);
2282         put_pid(pid);
2283         return ret;
2284 }
2285
2286 /**
2287  *      tiocspgrp               -       attempt to set process group
2288  *      @tty: tty passed by user
2289  *      @real_tty: tty side device matching tty passed by user
2290  *      @p: pid pointer
2291  *
2292  *      Set the process group of the tty to the session passed. Only
2293  *      permitted where the tty session is our session.
2294  *
2295  *      Locking: RCU, ctrl lock
2296  */
2297
2298 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2299 {
2300         struct pid *pgrp;
2301         pid_t pgrp_nr;
2302         int retval = tty_check_change(real_tty);
2303         unsigned long flags;
2304
2305         if (retval == -EIO)
2306                 return -ENOTTY;
2307         if (retval)
2308                 return retval;
2309         if (!current->signal->tty ||
2310             (current->signal->tty != real_tty) ||
2311             (real_tty->session != task_session(current)))
2312                 return -ENOTTY;
2313         if (get_user(pgrp_nr, p))
2314                 return -EFAULT;
2315         if (pgrp_nr < 0)
2316                 return -EINVAL;
2317         rcu_read_lock();
2318         pgrp = find_vpid(pgrp_nr);
2319         retval = -ESRCH;
2320         if (!pgrp)
2321                 goto out_unlock;
2322         retval = -EPERM;
2323         if (session_of_pgrp(pgrp) != task_session(current))
2324                 goto out_unlock;
2325         retval = 0;
2326         spin_lock_irqsave(&tty->ctrl_lock, flags);
2327         put_pid(real_tty->pgrp);
2328         real_tty->pgrp = get_pid(pgrp);
2329         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2330 out_unlock:
2331         rcu_read_unlock();
2332         return retval;
2333 }
2334
2335 /**
2336  *      tiocgsid                -       get session id
2337  *      @tty: tty passed by user
2338  *      @real_tty: tty side of the tty pased by the user if a pty else the tty
2339  *      @p: pointer to returned session id
2340  *
2341  *      Obtain the session id of the tty. If there is no session
2342  *      return an error.
2343  *
2344  *      Locking: none. Reference to current->signal->tty is safe.
2345  */
2346
2347 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2348 {
2349         /*
2350          * (tty == real_tty) is a cheap way of
2351          * testing if the tty is NOT a master pty.
2352         */
2353         if (tty == real_tty && current->signal->tty != real_tty)
2354                 return -ENOTTY;
2355         if (!real_tty->session)
2356                 return -ENOTTY;
2357         return put_user(pid_vnr(real_tty->session), p);
2358 }
2359
2360 /**
2361  *      tiocsetd        -       set line discipline
2362  *      @tty: tty device
2363  *      @p: pointer to user data
2364  *
2365  *      Set the line discipline according to user request.
2366  *
2367  *      Locking: see tty_set_ldisc, this function is just a helper
2368  */
2369
2370 static int tiocsetd(struct tty_struct *tty, int __user *p)
2371 {
2372         int ldisc;
2373         int ret;
2374
2375         if (get_user(ldisc, p))
2376                 return -EFAULT;
2377
2378         lock_kernel();
2379         ret = tty_set_ldisc(tty, ldisc);
2380         unlock_kernel();
2381
2382         return ret;
2383 }
2384
2385 /**
2386  *      send_break      -       performed time break
2387  *      @tty: device to break on
2388  *      @duration: timeout in mS
2389  *
2390  *      Perform a timed break on hardware that lacks its own driver level
2391  *      timed break functionality.
2392  *
2393  *      Locking:
2394  *              atomic_write_lock serializes
2395  *
2396  */
2397
2398 static int send_break(struct tty_struct *tty, unsigned int duration)
2399 {
2400         int retval;
2401
2402         if (tty->ops->break_ctl == NULL)
2403                 return 0;
2404
2405         if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2406                 retval = tty->ops->break_ctl(tty, duration);
2407         else {
2408                 /* Do the work ourselves */
2409                 if (tty_write_lock(tty, 0) < 0)
2410                         return -EINTR;
2411                 retval = tty->ops->break_ctl(tty, -1);
2412                 if (retval)
2413                         goto out;
2414                 if (!signal_pending(current))
2415                         msleep_interruptible(duration);
2416                 retval = tty->ops->break_ctl(tty, 0);
2417 out:
2418                 tty_write_unlock(tty);
2419                 if (signal_pending(current))
2420                         retval = -EINTR;
2421         }
2422         return retval;
2423 }
2424
2425 /**
2426  *      tty_tiocmget            -       get modem status
2427  *      @tty: tty device
2428  *      @file: user file pointer
2429  *      @p: pointer to result
2430  *
2431  *      Obtain the modem status bits from the tty driver if the feature
2432  *      is supported. Return -EINVAL if it is not available.
2433  *
2434  *      Locking: none (up to the driver)
2435  */
2436
2437 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
2438 {
2439         int retval = -EINVAL;
2440
2441         if (tty->ops->tiocmget) {
2442                 retval = tty->ops->tiocmget(tty, file);
2443
2444                 if (retval >= 0)
2445                         retval = put_user(retval, p);
2446         }
2447         return retval;
2448 }
2449
2450 /**
2451  *      tty_tiocmset            -       set modem status
2452  *      @tty: tty device
2453  *      @file: user file pointer
2454  *      @cmd: command - clear bits, set bits or set all
2455  *      @p: pointer to desired bits
2456  *
2457  *      Set the modem status bits from the tty driver if the feature
2458  *      is supported. Return -EINVAL if it is not available.
2459  *
2460  *      Locking: none (up to the driver)
2461  */
2462
2463 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
2464              unsigned __user *p)
2465 {
2466         int retval;
2467         unsigned int set, clear, val;
2468
2469         if (tty->ops->tiocmset == NULL)
2470                 return -EINVAL;
2471
2472         retval = get_user(val, p);
2473         if (retval)
2474                 return retval;
2475         set = clear = 0;
2476         switch (cmd) {
2477         case TIOCMBIS:
2478                 set = val;
2479                 break;
2480         case TIOCMBIC:
2481                 clear = val;
2482                 break;
2483         case TIOCMSET:
2484                 set = val;
2485                 clear = ~val;
2486                 break;
2487         }
2488         set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2489         clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2490         return tty->ops->tiocmset(tty, file, set, clear);
2491 }
2492
2493 /*
2494  * Split this up, as gcc can choke on it otherwise..
2495  */
2496 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2497 {
2498         struct tty_struct *tty, *real_tty;
2499         void __user *p = (void __user *)arg;
2500         int retval;
2501         struct tty_ldisc *ld;
2502         struct inode *inode = file->f_dentry->d_inode;
2503
2504         tty = (struct tty_struct *)file->private_data;
2505         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2506                 return -EINVAL;
2507
2508         real_tty = tty;
2509         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2510             tty->driver->subtype == PTY_TYPE_MASTER)
2511                 real_tty = tty->link;
2512
2513
2514         /*
2515          * Factor out some common prep work
2516          */
2517         switch (cmd) {
2518         case TIOCSETD:
2519         case TIOCSBRK:
2520         case TIOCCBRK:
2521         case TCSBRK:
2522         case TCSBRKP:
2523                 retval = tty_check_change(tty);
2524                 if (retval)
2525                         return retval;
2526                 if (cmd != TIOCCBRK) {
2527                         tty_wait_until_sent(tty, 0);
2528                         if (signal_pending(current))
2529                                 return -EINTR;
2530                 }
2531                 break;
2532         }
2533
2534         /*
2535          *      Now do the stuff.
2536          */
2537         switch (cmd) {
2538         case TIOCSTI:
2539                 return tiocsti(tty, p);
2540         case TIOCGWINSZ:
2541                 return tiocgwinsz(real_tty, p);
2542         case TIOCSWINSZ:
2543                 return tiocswinsz(tty, real_tty, p);
2544         case TIOCCONS:
2545                 return real_tty != tty ? -EINVAL : tioccons(file);
2546         case FIONBIO:
2547                 return fionbio(file, p);
2548         case TIOCEXCL:
2549                 set_bit(TTY_EXCLUSIVE, &tty->flags);
2550                 return 0;
2551         case TIOCNXCL:
2552                 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2553                 return 0;
2554         case TIOCNOTTY:
2555                 if (current->signal->tty != tty)
2556                         return -ENOTTY;
2557                 no_tty();
2558                 return 0;
2559         case TIOCSCTTY:
2560                 return tiocsctty(tty, arg);
2561         case TIOCGPGRP:
2562                 return tiocgpgrp(tty, real_tty, p);
2563         case TIOCSPGRP:
2564                 return tiocspgrp(tty, real_tty, p);
2565         case TIOCGSID:
2566                 return tiocgsid(tty, real_tty, p);
2567         case TIOCGETD:
2568                 return put_user(tty->ldisc.ops->num, (int __user *)p);
2569         case TIOCSETD:
2570                 return tiocsetd(tty, p);
2571         /*
2572          * Break handling
2573          */
2574         case TIOCSBRK:  /* Turn break on, unconditionally */
2575                 if (tty->ops->break_ctl)
2576                         return tty->ops->break_ctl(tty, -1);
2577                 return 0;
2578         case TIOCCBRK:  /* Turn break off, unconditionally */
2579                 if (tty->ops->break_ctl)
2580                         return tty->ops->break_ctl(tty, 0);
2581                 return 0;
2582         case TCSBRK:   /* SVID version: non-zero arg --> no break */
2583                 /* non-zero arg means wait for all output data
2584                  * to be sent (performed above) but don't send break.
2585                  * This is used by the tcdrain() termios function.
2586                  */
2587                 if (!arg)
2588                         return send_break(tty, 250);
2589                 return 0;
2590         case TCSBRKP:   /* support for POSIX tcsendbreak() */
2591                 return send_break(tty, arg ? arg*100 : 250);
2592
2593         case TIOCMGET:
2594                 return tty_tiocmget(tty, file, p);
2595         case TIOCMSET:
2596         case TIOCMBIC:
2597         case TIOCMBIS:
2598                 return tty_tiocmset(tty, file, cmd, p);
2599         case TCFLSH:
2600                 switch (arg) {
2601                 case TCIFLUSH:
2602                 case TCIOFLUSH:
2603                 /* flush tty buffer and allow ldisc to process ioctl */
2604                         tty_buffer_flush(tty);
2605                         break;
2606                 }
2607                 break;
2608         }
2609         if (tty->ops->ioctl) {
2610                 retval = (tty->ops->ioctl)(tty, file, cmd, arg);
2611                 if (retval != -ENOIOCTLCMD)
2612                         return retval;
2613         }
2614         ld = tty_ldisc_ref_wait(tty);
2615         retval = -EINVAL;
2616         if (ld->ops->ioctl) {
2617                 retval = ld->ops->ioctl(tty, file, cmd, arg);
2618                 if (retval == -ENOIOCTLCMD)
2619                         retval = -EINVAL;
2620         }
2621         tty_ldisc_deref(ld);
2622         return retval;
2623 }
2624
2625 #ifdef CONFIG_COMPAT
2626 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2627                                 unsigned long arg)
2628 {
2629         struct inode *inode = file->f_dentry->d_inode;
2630         struct tty_struct *tty = file->private_data;
2631         struct tty_ldisc *ld;
2632         int retval = -ENOIOCTLCMD;
2633
2634         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2635                 return -EINVAL;
2636
2637         if (tty->ops->compat_ioctl) {
2638                 retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
2639                 if (retval != -ENOIOCTLCMD)
2640                         return retval;
2641         }
2642
2643         ld = tty_ldisc_ref_wait(tty);
2644         if (ld->ops->compat_ioctl)
2645                 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2646         tty_ldisc_deref(ld);
2647
2648         return retval;
2649 }
2650 #endif
2651
2652 /*
2653  * This implements the "Secure Attention Key" ---  the idea is to
2654  * prevent trojan horses by killing all processes associated with this
2655  * tty when the user hits the "Secure Attention Key".  Required for
2656  * super-paranoid applications --- see the Orange Book for more details.
2657  *
2658  * This code could be nicer; ideally it should send a HUP, wait a few
2659  * seconds, then send a INT, and then a KILL signal.  But you then
2660  * have to coordinate with the init process, since all processes associated
2661  * with the current tty must be dead before the new getty is allowed
2662  * to spawn.
2663  *
2664  * Now, if it would be correct ;-/ The current code has a nasty hole -
2665  * it doesn't catch files in flight. We may send the descriptor to ourselves
2666  * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2667  *
2668  * Nasty bug: do_SAK is being called in interrupt context.  This can
2669  * deadlock.  We punt it up to process context.  AKPM - 16Mar2001
2670  */
2671 void __do_SAK(struct tty_struct *tty)
2672 {
2673 #ifdef TTY_SOFT_SAK
2674         tty_hangup(tty);
2675 #else
2676         struct task_struct *g, *p;
2677         struct pid *session;
2678         int             i;
2679         struct file     *filp;
2680         struct fdtable *fdt;
2681
2682         if (!tty)
2683                 return;
2684         session = tty->session;
2685
2686         tty_ldisc_flush(tty);
2687
2688         tty_driver_flush_buffer(tty);
2689
2690         read_lock(&tasklist_lock);
2691         /* Kill the entire session */
2692         do_each_pid_task(session, PIDTYPE_SID, p) {
2693                 printk(KERN_NOTICE "SAK: killed process %d"
2694                         " (%s): task_session_nr(p)==tty->session\n",
2695                         task_pid_nr(p), p->comm);
2696                 send_sig(SIGKILL, p, 1);
2697         } while_each_pid_task(session, PIDTYPE_SID, p);
2698         /* Now kill any processes that happen to have the
2699          * tty open.
2700          */
2701         do_each_thread(g, p) {
2702                 if (p->signal->tty == tty) {
2703                         printk(KERN_NOTICE "SAK: killed process %d"
2704                             " (%s): task_session_nr(p)==tty->session\n",
2705                             task_pid_nr(p), p->comm);
2706                         send_sig(SIGKILL, p, 1);
2707                         continue;
2708                 }
2709                 task_lock(p);
2710                 if (p->files) {
2711                         /*
2712                          * We don't take a ref to the file, so we must
2713                          * hold ->file_lock instead.
2714                          */
2715                         spin_lock(&p->files->file_lock);
2716                         fdt = files_fdtable(p->files);
2717                         for (i = 0; i < fdt->max_fds; i++) {
2718                                 filp = fcheck_files(p->files, i);
2719                                 if (!filp)
2720                                         continue;
2721                                 if (filp->f_op->read == tty_read &&
2722                                     filp->private_data == tty) {
2723                                         printk(KERN_NOTICE "SAK: killed process %d"
2724                                             " (%s): fd#%d opened to the tty\n",
2725                                             task_pid_nr(p), p->comm, i);
2726                                         force_sig(SIGKILL, p);
2727                                         break;
2728                                 }
2729                         }
2730                         spin_unlock(&p->files->file_lock);
2731                 }
2732                 task_unlock(p);
2733         } while_each_thread(g, p);
2734         read_unlock(&tasklist_lock);
2735 #endif
2736 }
2737
2738 static void do_SAK_work(struct work_struct *work)
2739 {
2740         struct tty_struct *tty =
2741                 container_of(work, struct tty_struct, SAK_work);
2742         __do_SAK(tty);
2743 }
2744
2745 /*
2746  * The tq handling here is a little racy - tty->SAK_work may already be queued.
2747  * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2748  * the values which we write to it will be identical to the values which it
2749  * already has. --akpm
2750  */
2751 void do_SAK(struct tty_struct *tty)
2752 {
2753         if (!tty)
2754                 return;
2755         schedule_work(&tty->SAK_work);
2756 }
2757
2758 EXPORT_SYMBOL(do_SAK);
2759
2760 /**
2761  *      initialize_tty_struct
2762  *      @tty: tty to initialize
2763  *
2764  *      This subroutine initializes a tty structure that has been newly
2765  *      allocated.
2766  *
2767  *      Locking: none - tty in question must not be exposed at this point
2768  */
2769
2770 void initialize_tty_struct(struct tty_struct *tty,
2771                 struct tty_driver *driver, int idx)
2772 {
2773         memset(tty, 0, sizeof(struct tty_struct));
2774         kref_init(&tty->kref);
2775         tty->magic = TTY_MAGIC;
2776         tty_ldisc_init(tty);
2777         tty->session = NULL;
2778         tty->pgrp = NULL;
2779         tty->overrun_time = jiffies;
2780         tty->buf.head = tty->buf.tail = NULL;
2781         tty_buffer_init(tty);
2782         mutex_init(&tty->termios_mutex);
2783         init_waitqueue_head(&tty->write_wait);
2784         init_waitqueue_head(&tty->read_wait);
2785         INIT_WORK(&tty->hangup_work, do_tty_hangup);
2786         mutex_init(&tty->atomic_read_lock);
2787         mutex_init(&tty->atomic_write_lock);
2788         spin_lock_init(&tty->read_lock);
2789         spin_lock_init(&tty->ctrl_lock);
2790         INIT_LIST_HEAD(&tty->tty_files);
2791         INIT_WORK(&tty->SAK_work, do_SAK_work);
2792
2793         tty->driver = driver;
2794         tty->ops = driver->ops;
2795         tty->index = idx;
2796         tty_line_name(driver, idx, tty->name);
2797 }
2798
2799 /**
2800  *      tty_put_char    -       write one character to a tty
2801  *      @tty: tty
2802  *      @ch: character
2803  *
2804  *      Write one byte to the tty using the provided put_char method
2805  *      if present. Returns the number of characters successfully output.
2806  *
2807  *      Note: the specific put_char operation in the driver layer may go
2808  *      away soon. Don't call it directly, use this method
2809  */
2810
2811 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2812 {
2813         if (tty->ops->put_char)
2814                 return tty->ops->put_char(tty, ch);
2815         return tty->ops->write(tty, &ch, 1);
2816 }
2817 EXPORT_SYMBOL_GPL(tty_put_char);
2818
2819 struct class *tty_class;
2820
2821 /**
2822  *      tty_register_device - register a tty device
2823  *      @driver: the tty driver that describes the tty device
2824  *      @index: the index in the tty driver for this tty device
2825  *      @device: a struct device that is associated with this tty device.
2826  *              This field is optional, if there is no known struct device
2827  *              for this tty device it can be set to NULL safely.
2828  *
2829  *      Returns a pointer to the struct device for this tty device
2830  *      (or ERR_PTR(-EFOO) on error).
2831  *
2832  *      This call is required to be made to register an individual tty device
2833  *      if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set.  If
2834  *      that bit is not set, this function should not be called by a tty
2835  *      driver.
2836  *
2837  *      Locking: ??
2838  */
2839
2840 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2841                                    struct device *device)
2842 {
2843         char name[64];
2844         dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
2845
2846         if (index >= driver->num) {
2847                 printk(KERN_ERR "Attempt to register invalid tty line number "
2848                        " (%d).\n", index);
2849                 return ERR_PTR(-EINVAL);
2850         }
2851
2852         if (driver->type == TTY_DRIVER_TYPE_PTY)
2853                 pty_line_name(driver, index, name);
2854         else
2855                 tty_line_name(driver, index, name);
2856
2857         return device_create(tty_class, device, dev, NULL, name);
2858 }
2859 EXPORT_SYMBOL(tty_register_device);
2860
2861 /**
2862  *      tty_unregister_device - unregister a tty device
2863  *      @driver: the tty driver that describes the tty device
2864  *      @index: the index in the tty driver for this tty device
2865  *
2866  *      If a tty device is registered with a call to tty_register_device() then
2867  *      this function must be called when the tty device is gone.
2868  *
2869  *      Locking: ??
2870  */
2871
2872 void tty_unregister_device(struct tty_driver *driver, unsigned index)
2873 {
2874         device_destroy(tty_class,
2875                 MKDEV(driver->major, driver->minor_start) + index);
2876 }
2877 EXPORT_SYMBOL(tty_unregister_device);
2878
2879 struct tty_driver *alloc_tty_driver(int lines)
2880 {
2881         struct tty_driver *driver;
2882
2883         driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
2884         if (driver) {
2885                 kref_init(&driver->kref);
2886                 driver->magic = TTY_DRIVER_MAGIC;
2887                 driver->num = lines;
2888                 /* later we'll move allocation of tables here */
2889         }
2890         return driver;
2891 }
2892 EXPORT_SYMBOL(alloc_tty_driver);
2893
2894 static void destruct_tty_driver(struct kref *kref)
2895 {
2896         struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
2897         int i;
2898         struct ktermios *tp;
2899         void *p;
2900
2901         if (driver->flags & TTY_DRIVER_INSTALLED) {
2902                 /*
2903                  * Free the termios and termios_locked structures because
2904                  * we don't want to get memory leaks when modular tty
2905                  * drivers are removed from the kernel.
2906                  */
2907                 for (i = 0; i < driver->num; i++) {
2908                         tp = driver->termios[i];
2909                         if (tp) {
2910                                 driver->termios[i] = NULL;
2911                                 kfree(tp);
2912                         }
2913                         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
2914                                 tty_unregister_device(driver, i);
2915                 }
2916                 p = driver->ttys;
2917                 proc_tty_unregister_driver(driver);
2918                 driver->ttys = NULL;
2919                 driver->termios = NULL;
2920                 kfree(p);
2921                 cdev_del(&driver->cdev);
2922         }
2923         kfree(driver);
2924 }
2925
2926 void tty_driver_kref_put(struct tty_driver *driver)
2927 {
2928         kref_put(&driver->kref, destruct_tty_driver);
2929 }
2930 EXPORT_SYMBOL(tty_driver_kref_put);
2931
2932 void tty_set_operations(struct tty_driver *driver,
2933                         const struct tty_operations *op)
2934 {
2935         driver->ops = op;
2936 };
2937 EXPORT_SYMBOL(tty_set_operations);
2938
2939 void put_tty_driver(struct tty_driver *d)
2940 {
2941         tty_driver_kref_put(d);
2942 }
2943 EXPORT_SYMBOL(put_tty_driver);
2944
2945 /*
2946  * Called by a tty driver to register itself.
2947  */
2948 int tty_register_driver(struct tty_driver *driver)
2949 {
2950         int error;
2951         int i;
2952         dev_t dev;
2953         void **p = NULL;
2954
2955         if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
2956                 p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
2957                 if (!p)
2958                         return -ENOMEM;
2959         }
2960
2961         if (!driver->major) {
2962                 error = alloc_chrdev_region(&dev, driver->minor_start,
2963                                                 driver->num, driver->name);
2964                 if (!error) {
2965                         driver->major = MAJOR(dev);
2966                         driver->minor_start = MINOR(dev);
2967                 }
2968         } else {
2969                 dev = MKDEV(driver->major, driver->minor_start);
2970                 error = register_chrdev_region(dev, driver->num, driver->name);
2971         }
2972         if (error < 0) {
2973                 kfree(p);
2974                 return error;
2975         }
2976
2977         if (p) {
2978                 driver->ttys = (struct tty_struct **)p;
2979                 driver->termios = (struct ktermios **)(p + driver->num);
2980         } else {
2981                 driver->ttys = NULL;
2982                 driver->termios = NULL;
2983         }
2984
2985         cdev_init(&driver->cdev, &tty_fops);
2986         driver->cdev.owner = driver->owner;
2987         error = cdev_add(&driver->cdev, dev, driver->num);
2988         if (error) {
2989                 unregister_chrdev_region(dev, driver->num);
2990                 driver->ttys = NULL;
2991                 driver->termios = NULL;
2992                 kfree(p);
2993                 return error;
2994         }
2995
2996         mutex_lock(&tty_mutex);
2997         list_add(&driver->tty_drivers, &tty_drivers);
2998         mutex_unlock(&tty_mutex);
2999
3000         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3001                 for (i = 0; i < driver->num; i++)
3002                     tty_register_device(driver, i, NULL);
3003         }
3004         proc_tty_register_driver(driver);
3005         driver->flags |= TTY_DRIVER_INSTALLED;
3006         return 0;
3007 }
3008
3009 EXPORT_SYMBOL(tty_register_driver);
3010
3011 /*
3012  * Called by a tty driver to unregister itself.
3013  */
3014 int tty_unregister_driver(struct tty_driver *driver)
3015 {
3016 #if 0
3017         /* FIXME */
3018         if (driver->refcount)
3019                 return -EBUSY;
3020 #endif
3021         unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3022                                 driver->num);
3023         mutex_lock(&tty_mutex);
3024         list_del(&driver->tty_drivers);
3025         mutex_unlock(&tty_mutex);
3026         return 0;
3027 }
3028
3029 EXPORT_SYMBOL(tty_unregister_driver);
3030
3031 dev_t tty_devnum(struct tty_struct *tty)
3032 {
3033         return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3034 }
3035 EXPORT_SYMBOL(tty_devnum);
3036
3037 void proc_clear_tty(struct task_struct *p)
3038 {
3039         unsigned long flags;
3040         struct tty_struct *tty;
3041         spin_lock_irqsave(&p->sighand->siglock, flags);
3042         tty = p->signal->tty;
3043         p->signal->tty = NULL;
3044         spin_unlock_irqrestore(&p->sighand->siglock, flags);
3045         tty_kref_put(tty);
3046 }
3047
3048 /* Called under the sighand lock */
3049
3050 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3051 {
3052         if (tty) {
3053                 unsigned long flags;
3054                 /* We should not have a session or pgrp to put here but.... */
3055                 spin_lock_irqsave(&tty->ctrl_lock, flags);
3056                 put_pid(tty->session);
3057                 put_pid(tty->pgrp);
3058                 tty->pgrp = get_pid(task_pgrp(tsk));
3059                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3060                 tty->session = get_pid(task_session(tsk));
3061                 if (tsk->signal->tty) {
3062                         printk(KERN_DEBUG "tty not NULL!!\n");
3063                         tty_kref_put(tsk->signal->tty);
3064                 }
3065         }
3066         put_pid(tsk->signal->tty_old_pgrp);
3067         tsk->signal->tty = tty_kref_get(tty);
3068         tsk->signal->tty_old_pgrp = NULL;
3069 }
3070
3071 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3072 {
3073         spin_lock_irq(&tsk->sighand->siglock);
3074         __proc_set_tty(tsk, tty);
3075         spin_unlock_irq(&tsk->sighand->siglock);
3076 }
3077
3078 struct tty_struct *get_current_tty(void)
3079 {
3080         struct tty_struct *tty;
3081         unsigned long flags;
3082
3083         spin_lock_irqsave(&current->sighand->siglock, flags);
3084         tty = tty_kref_get(current->signal->tty);
3085         spin_unlock_irqrestore(&current->sighand->siglock, flags);
3086         return tty;
3087 }
3088 EXPORT_SYMBOL_GPL(get_current_tty);
3089
3090 void tty_default_fops(struct file_operations *fops)
3091 {
3092         *fops = tty_fops;
3093 }
3094
3095 /*
3096  * Initialize the console device. This is called *early*, so
3097  * we can't necessarily depend on lots of kernel help here.
3098  * Just do some early initializations, and do the complex setup
3099  * later.
3100  */
3101 void __init console_init(void)
3102 {
3103         initcall_t *call;
3104
3105         /* Setup the default TTY line discipline. */
3106         tty_ldisc_begin();
3107
3108         /*
3109          * set up the console device so that later boot sequences can
3110          * inform about problems etc..
3111          */
3112         call = __con_initcall_start;
3113         while (call < __con_initcall_end) {
3114                 (*call)();
3115                 call++;
3116         }
3117 }
3118
3119 static int __init tty_class_init(void)
3120 {
3121         tty_class = class_create(THIS_MODULE, "tty");
3122         if (IS_ERR(tty_class))
3123                 return PTR_ERR(tty_class);
3124         return 0;
3125 }
3126
3127 postcore_initcall(tty_class_init);
3128
3129 /* 3/2004 jmc: why do these devices exist? */
3130
3131 static struct cdev tty_cdev, console_cdev;
3132
3133 /*
3134  * Ok, now we can initialize the rest of the tty devices and can count
3135  * on memory allocations, interrupts etc..
3136  */
3137 static int __init tty_init(void)
3138 {
3139         cdev_init(&tty_cdev, &tty_fops);
3140         if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3141             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3142                 panic("Couldn't register /dev/tty driver\n");
3143         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
3144                               "tty");
3145
3146         cdev_init(&console_cdev, &console_fops);
3147         if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3148             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3149                 panic("Couldn't register /dev/console driver\n");
3150         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3151                               "console");
3152
3153 #ifdef CONFIG_VT
3154         vty_init(&console_fops);
3155 #endif
3156         return 0;
3157 }
3158 module_init(tty_init);