Merge branch 'topic/ca0106' into for-linus
[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 invoked in parallel for each device.
1115  */
1116
1117 static ssize_t tty_write(struct file *file, const char __user *buf,
1118                                                 size_t count, loff_t *ppos)
1119 {
1120         struct tty_struct *tty;
1121         struct inode *inode = file->f_path.dentry->d_inode;
1122         ssize_t ret;
1123         struct tty_ldisc *ld;
1124
1125         tty = (struct tty_struct *)file->private_data;
1126         if (tty_paranoia_check(tty, inode, "tty_write"))
1127                 return -EIO;
1128         if (!tty || !tty->ops->write ||
1129                 (test_bit(TTY_IO_ERROR, &tty->flags)))
1130                         return -EIO;
1131         /* Short term debug to catch buggy drivers */
1132         if (tty->ops->write_room == NULL)
1133                 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1134                         tty->driver->name);
1135         ld = tty_ldisc_ref_wait(tty);
1136         if (!ld->ops->write)
1137                 ret = -EIO;
1138         else
1139                 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1140         tty_ldisc_deref(ld);
1141         return ret;
1142 }
1143
1144 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1145                                                 size_t count, loff_t *ppos)
1146 {
1147         struct file *p = NULL;
1148
1149         spin_lock(&redirect_lock);
1150         if (redirect) {
1151                 get_file(redirect);
1152                 p = redirect;
1153         }
1154         spin_unlock(&redirect_lock);
1155
1156         if (p) {
1157                 ssize_t res;
1158                 res = vfs_write(p, buf, count, &p->f_pos);
1159                 fput(p);
1160                 return res;
1161         }
1162         return tty_write(file, buf, count, ppos);
1163 }
1164
1165 static char ptychar[] = "pqrstuvwxyzabcde";
1166
1167 /**
1168  *      pty_line_name   -       generate name for a pty
1169  *      @driver: the tty driver in use
1170  *      @index: the minor number
1171  *      @p: output buffer of at least 6 bytes
1172  *
1173  *      Generate a name from a driver reference and write it to the output
1174  *      buffer.
1175  *
1176  *      Locking: None
1177  */
1178 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1179 {
1180         int i = index + driver->name_base;
1181         /* ->name is initialized to "ttyp", but "tty" is expected */
1182         sprintf(p, "%s%c%x",
1183                 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1184                 ptychar[i >> 4 & 0xf], i & 0xf);
1185 }
1186
1187 /**
1188  *      tty_line_name   -       generate name for a tty
1189  *      @driver: the tty driver in use
1190  *      @index: the minor number
1191  *      @p: output buffer of at least 7 bytes
1192  *
1193  *      Generate a name from a driver reference and write it to the output
1194  *      buffer.
1195  *
1196  *      Locking: None
1197  */
1198 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1199 {
1200         sprintf(p, "%s%d", driver->name, index + driver->name_base);
1201 }
1202
1203 /**
1204  *      tty_driver_lookup_tty() - find an existing tty, if any
1205  *      @driver: the driver for the tty
1206  *      @idx:    the minor number
1207  *
1208  *      Return the tty, if found or ERR_PTR() otherwise.
1209  *
1210  *      Locking: tty_mutex must be held. If tty is found, the mutex must
1211  *      be held until the 'fast-open' is also done. Will change once we
1212  *      have refcounting in the driver and per driver locking
1213  */
1214 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1215                 struct inode *inode, int idx)
1216 {
1217         struct tty_struct *tty;
1218
1219         if (driver->ops->lookup)
1220                 return driver->ops->lookup(driver, inode, idx);
1221
1222         tty = driver->ttys[idx];
1223         return tty;
1224 }
1225
1226 /**
1227  *      tty_init_termios        -  helper for termios setup
1228  *      @tty: the tty to set up
1229  *
1230  *      Initialise the termios structures for this tty. Thus runs under
1231  *      the tty_mutex currently so we can be relaxed about ordering.
1232  */
1233
1234 int tty_init_termios(struct tty_struct *tty)
1235 {
1236         struct ktermios *tp;
1237         int idx = tty->index;
1238
1239         tp = tty->driver->termios[idx];
1240         if (tp == NULL) {
1241                 tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
1242                 if (tp == NULL)
1243                         return -ENOMEM;
1244                 memcpy(tp, &tty->driver->init_termios,
1245                                                 sizeof(struct ktermios));
1246                 tty->driver->termios[idx] = tp;
1247         }
1248         tty->termios = tp;
1249         tty->termios_locked = tp + 1;
1250
1251         /* Compatibility until drivers always set this */
1252         tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1253         tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1254         return 0;
1255 }
1256
1257 /**
1258  *      tty_driver_install_tty() - install a tty entry in the driver
1259  *      @driver: the driver for the tty
1260  *      @tty: the tty
1261  *
1262  *      Install a tty object into the driver tables. The tty->index field
1263  *      will be set by the time this is called. This method is responsible
1264  *      for ensuring any need additional structures are allocated and
1265  *      configured.
1266  *
1267  *      Locking: tty_mutex for now
1268  */
1269 static int tty_driver_install_tty(struct tty_driver *driver,
1270                                                 struct tty_struct *tty)
1271 {
1272         int idx = tty->index;
1273
1274         if (driver->ops->install)
1275                 return driver->ops->install(driver, tty);
1276
1277         if (tty_init_termios(tty) == 0) {
1278                 tty_driver_kref_get(driver);
1279                 tty->count++;
1280                 driver->ttys[idx] = tty;
1281                 return 0;
1282         }
1283         return -ENOMEM;
1284 }
1285
1286 /**
1287  *      tty_driver_remove_tty() - remove a tty from the driver tables
1288  *      @driver: the driver for the tty
1289  *      @idx:    the minor number
1290  *
1291  *      Remvoe a tty object from the driver tables. The tty->index field
1292  *      will be set by the time this is called.
1293  *
1294  *      Locking: tty_mutex for now
1295  */
1296 static void tty_driver_remove_tty(struct tty_driver *driver,
1297                                                 struct tty_struct *tty)
1298 {
1299         if (driver->ops->remove)
1300                 driver->ops->remove(driver, tty);
1301         else
1302                 driver->ttys[tty->index] = NULL;
1303 }
1304
1305 /*
1306  *      tty_reopen()    - fast re-open of an open tty
1307  *      @tty    - the tty to open
1308  *
1309  *      Return 0 on success, -errno on error.
1310  *
1311  *      Locking: tty_mutex must be held from the time the tty was found
1312  *               till this open completes.
1313  */
1314 static int tty_reopen(struct tty_struct *tty)
1315 {
1316         struct tty_driver *driver = tty->driver;
1317
1318         if (test_bit(TTY_CLOSING, &tty->flags))
1319                 return -EIO;
1320
1321         if (driver->type == TTY_DRIVER_TYPE_PTY &&
1322             driver->subtype == PTY_TYPE_MASTER) {
1323                 /*
1324                  * special case for PTY masters: only one open permitted,
1325                  * and the slave side open count is incremented as well.
1326                  */
1327                 if (tty->count)
1328                         return -EIO;
1329
1330                 tty->link->count++;
1331         }
1332         tty->count++;
1333         tty->driver = driver; /* N.B. why do this every time?? */
1334
1335         WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1336
1337         return 0;
1338 }
1339
1340 /**
1341  *      tty_init_dev            -       initialise a tty device
1342  *      @driver: tty driver we are opening a device on
1343  *      @idx: device index
1344  *      @ret_tty: returned tty structure
1345  *      @first_ok: ok to open a new device (used by ptmx)
1346  *
1347  *      Prepare a tty device. This may not be a "new" clean device but
1348  *      could also be an active device. The pty drivers require special
1349  *      handling because of this.
1350  *
1351  *      Locking:
1352  *              The function is called under the tty_mutex, which
1353  *      protects us from the tty struct or driver itself going away.
1354  *
1355  *      On exit the tty device has the line discipline attached and
1356  *      a reference count of 1. If a pair was created for pty/tty use
1357  *      and the other was a pty master then it too has a reference count of 1.
1358  *
1359  * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1360  * failed open.  The new code protects the open with a mutex, so it's
1361  * really quite straightforward.  The mutex locking can probably be
1362  * relaxed for the (most common) case of reopening a tty.
1363  */
1364
1365 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
1366                                                                 int first_ok)
1367 {
1368         struct tty_struct *tty;
1369         int retval;
1370
1371         /* Check if pty master is being opened multiple times */
1372         if (driver->subtype == PTY_TYPE_MASTER &&
1373                 (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok)
1374                 return ERR_PTR(-EIO);
1375
1376         /*
1377          * First time open is complex, especially for PTY devices.
1378          * This code guarantees that either everything succeeds and the
1379          * TTY is ready for operation, or else the table slots are vacated
1380          * and the allocated memory released.  (Except that the termios
1381          * and locked termios may be retained.)
1382          */
1383
1384         if (!try_module_get(driver->owner))
1385                 return ERR_PTR(-ENODEV);
1386
1387         tty = alloc_tty_struct();
1388         if (!tty)
1389                 goto fail_no_mem;
1390         initialize_tty_struct(tty, driver, idx);
1391
1392         retval = tty_driver_install_tty(driver, tty);
1393         if (retval < 0) {
1394                 free_tty_struct(tty);
1395                 module_put(driver->owner);
1396                 return ERR_PTR(retval);
1397         }
1398
1399         /*
1400          * Structures all installed ... call the ldisc open routines.
1401          * If we fail here just call release_tty to clean up.  No need
1402          * to decrement the use counts, as release_tty doesn't care.
1403          */
1404
1405         retval = tty_ldisc_setup(tty, tty->link);
1406         if (retval)
1407                 goto release_mem_out;
1408         return tty;
1409
1410 fail_no_mem:
1411         module_put(driver->owner);
1412         return ERR_PTR(-ENOMEM);
1413
1414         /* call the tty release_tty routine to clean out this slot */
1415 release_mem_out:
1416         if (printk_ratelimit())
1417                 printk(KERN_INFO "tty_init_dev: ldisc open failed, "
1418                                  "clearing slot %d\n", idx);
1419         release_tty(tty, idx);
1420         return ERR_PTR(retval);
1421 }
1422
1423 void tty_free_termios(struct tty_struct *tty)
1424 {
1425         struct ktermios *tp;
1426         int idx = tty->index;
1427         /* Kill this flag and push into drivers for locking etc */
1428         if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
1429                 /* FIXME: Locking on ->termios array */
1430                 tp = tty->termios;
1431                 tty->driver->termios[idx] = NULL;
1432                 kfree(tp);
1433         }
1434 }
1435 EXPORT_SYMBOL(tty_free_termios);
1436
1437 void tty_shutdown(struct tty_struct *tty)
1438 {
1439         tty_driver_remove_tty(tty->driver, tty);
1440         tty_free_termios(tty);
1441 }
1442 EXPORT_SYMBOL(tty_shutdown);
1443
1444 /**
1445  *      release_one_tty         -       release tty structure memory
1446  *      @kref: kref of tty we are obliterating
1447  *
1448  *      Releases memory associated with a tty structure, and clears out the
1449  *      driver table slots. This function is called when a device is no longer
1450  *      in use. It also gets called when setup of a device fails.
1451  *
1452  *      Locking:
1453  *              tty_mutex - sometimes only
1454  *              takes the file list lock internally when working on the list
1455  *      of ttys that the driver keeps.
1456  */
1457 static void release_one_tty(struct kref *kref)
1458 {
1459         struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1460         struct tty_driver *driver = tty->driver;
1461
1462         if (tty->ops->shutdown)
1463                 tty->ops->shutdown(tty);
1464         else
1465                 tty_shutdown(tty);
1466         tty->magic = 0;
1467         tty_driver_kref_put(driver);
1468         module_put(driver->owner);
1469
1470         file_list_lock();
1471         list_del_init(&tty->tty_files);
1472         file_list_unlock();
1473
1474         free_tty_struct(tty);
1475 }
1476
1477 /**
1478  *      tty_kref_put            -       release a tty kref
1479  *      @tty: tty device
1480  *
1481  *      Release a reference to a tty device and if need be let the kref
1482  *      layer destruct the object for us
1483  */
1484
1485 void tty_kref_put(struct tty_struct *tty)
1486 {
1487         if (tty)
1488                 kref_put(&tty->kref, release_one_tty);
1489 }
1490 EXPORT_SYMBOL(tty_kref_put);
1491
1492 /**
1493  *      release_tty             -       release tty structure memory
1494  *
1495  *      Release both @tty and a possible linked partner (think pty pair),
1496  *      and decrement the refcount of the backing module.
1497  *
1498  *      Locking:
1499  *              tty_mutex - sometimes only
1500  *              takes the file list lock internally when working on the list
1501  *      of ttys that the driver keeps.
1502  *              FIXME: should we require tty_mutex is held here ??
1503  *
1504  */
1505 static void release_tty(struct tty_struct *tty, int idx)
1506 {
1507         /* This should always be true but check for the moment */
1508         WARN_ON(tty->index != idx);
1509
1510         if (tty->link)
1511                 tty_kref_put(tty->link);
1512         tty_kref_put(tty);
1513 }
1514
1515 /*
1516  * Even releasing the tty structures is a tricky business.. We have
1517  * to be very careful that the structures are all released at the
1518  * same time, as interrupts might otherwise get the wrong pointers.
1519  *
1520  * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1521  * lead to double frees or releasing memory still in use.
1522  */
1523 void tty_release_dev(struct file *filp)
1524 {
1525         struct tty_struct *tty, *o_tty;
1526         int     pty_master, tty_closing, o_tty_closing, do_sleep;
1527         int     devpts;
1528         int     idx;
1529         char    buf[64];
1530         struct  inode *inode;
1531
1532         inode = filp->f_path.dentry->d_inode;
1533         tty = (struct tty_struct *)filp->private_data;
1534         if (tty_paranoia_check(tty, inode, "tty_release_dev"))
1535                 return;
1536
1537         check_tty_count(tty, "tty_release_dev");
1538
1539         tty_fasync(-1, filp, 0);
1540
1541         idx = tty->index;
1542         pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1543                       tty->driver->subtype == PTY_TYPE_MASTER);
1544         devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1545         o_tty = tty->link;
1546
1547 #ifdef TTY_PARANOIA_CHECK
1548         if (idx < 0 || idx >= tty->driver->num) {
1549                 printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
1550                                   "free (%s)\n", tty->name);
1551                 return;
1552         }
1553         if (!devpts) {
1554                 if (tty != tty->driver->ttys[idx]) {
1555                         printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
1556                                "for (%s)\n", idx, tty->name);
1557                         return;
1558                 }
1559                 if (tty->termios != tty->driver->termios[idx]) {
1560                         printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
1561                                "for (%s)\n",
1562                                idx, tty->name);
1563                         return;
1564                 }
1565         }
1566 #endif
1567
1568 #ifdef TTY_DEBUG_HANGUP
1569         printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
1570                tty_name(tty, buf), tty->count);
1571 #endif
1572
1573 #ifdef TTY_PARANOIA_CHECK
1574         if (tty->driver->other &&
1575              !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
1576                 if (o_tty != tty->driver->other->ttys[idx]) {
1577                         printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
1578                                           "not o_tty for (%s)\n",
1579                                idx, tty->name);
1580                         return;
1581                 }
1582                 if (o_tty->termios != tty->driver->other->termios[idx]) {
1583                         printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
1584                                           "not o_termios for (%s)\n",
1585                                idx, tty->name);
1586                         return;
1587                 }
1588                 if (o_tty->link != tty) {
1589                         printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
1590                         return;
1591                 }
1592         }
1593 #endif
1594         if (tty->ops->close)
1595                 tty->ops->close(tty, filp);
1596
1597         /*
1598          * Sanity check: if tty->count is going to zero, there shouldn't be
1599          * any waiters on tty->read_wait or tty->write_wait.  We test the
1600          * wait queues and kick everyone out _before_ actually starting to
1601          * close.  This ensures that we won't block while releasing the tty
1602          * structure.
1603          *
1604          * The test for the o_tty closing is necessary, since the master and
1605          * slave sides may close in any order.  If the slave side closes out
1606          * first, its count will be one, since the master side holds an open.
1607          * Thus this test wouldn't be triggered at the time the slave closes,
1608          * so we do it now.
1609          *
1610          * Note that it's possible for the tty to be opened again while we're
1611          * flushing out waiters.  By recalculating the closing flags before
1612          * each iteration we avoid any problems.
1613          */
1614         while (1) {
1615                 /* Guard against races with tty->count changes elsewhere and
1616                    opens on /dev/tty */
1617
1618                 mutex_lock(&tty_mutex);
1619                 tty_closing = tty->count <= 1;
1620                 o_tty_closing = o_tty &&
1621                         (o_tty->count <= (pty_master ? 1 : 0));
1622                 do_sleep = 0;
1623
1624                 if (tty_closing) {
1625                         if (waitqueue_active(&tty->read_wait)) {
1626                                 wake_up(&tty->read_wait);
1627                                 do_sleep++;
1628                         }
1629                         if (waitqueue_active(&tty->write_wait)) {
1630                                 wake_up(&tty->write_wait);
1631                                 do_sleep++;
1632                         }
1633                 }
1634                 if (o_tty_closing) {
1635                         if (waitqueue_active(&o_tty->read_wait)) {
1636                                 wake_up(&o_tty->read_wait);
1637                                 do_sleep++;
1638                         }
1639                         if (waitqueue_active(&o_tty->write_wait)) {
1640                                 wake_up(&o_tty->write_wait);
1641                                 do_sleep++;
1642                         }
1643                 }
1644                 if (!do_sleep)
1645                         break;
1646
1647                 printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
1648                                     "active!\n", tty_name(tty, buf));
1649                 mutex_unlock(&tty_mutex);
1650                 schedule();
1651         }
1652
1653         /*
1654          * The closing flags are now consistent with the open counts on
1655          * both sides, and we've completed the last operation that could
1656          * block, so it's safe to proceed with closing.
1657          */
1658         if (pty_master) {
1659                 if (--o_tty->count < 0) {
1660                         printk(KERN_WARNING "tty_release_dev: bad pty slave count "
1661                                             "(%d) for %s\n",
1662                                o_tty->count, tty_name(o_tty, buf));
1663                         o_tty->count = 0;
1664                 }
1665         }
1666         if (--tty->count < 0) {
1667                 printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
1668                        tty->count, tty_name(tty, buf));
1669                 tty->count = 0;
1670         }
1671
1672         /*
1673          * We've decremented tty->count, so we need to remove this file
1674          * descriptor off the tty->tty_files list; this serves two
1675          * purposes:
1676          *  - check_tty_count sees the correct number of file descriptors
1677          *    associated with this tty.
1678          *  - do_tty_hangup no longer sees this file descriptor as
1679          *    something that needs to be handled for hangups.
1680          */
1681         file_kill(filp);
1682         filp->private_data = NULL;
1683
1684         /*
1685          * Perform some housekeeping before deciding whether to return.
1686          *
1687          * Set the TTY_CLOSING flag if this was the last open.  In the
1688          * case of a pty we may have to wait around for the other side
1689          * to close, and TTY_CLOSING makes sure we can't be reopened.
1690          */
1691         if (tty_closing)
1692                 set_bit(TTY_CLOSING, &tty->flags);
1693         if (o_tty_closing)
1694                 set_bit(TTY_CLOSING, &o_tty->flags);
1695
1696         /*
1697          * If _either_ side is closing, make sure there aren't any
1698          * processes that still think tty or o_tty is their controlling
1699          * tty.
1700          */
1701         if (tty_closing || o_tty_closing) {
1702                 read_lock(&tasklist_lock);
1703                 session_clear_tty(tty->session);
1704                 if (o_tty)
1705                         session_clear_tty(o_tty->session);
1706                 read_unlock(&tasklist_lock);
1707         }
1708
1709         mutex_unlock(&tty_mutex);
1710
1711         /* check whether both sides are closing ... */
1712         if (!tty_closing || (o_tty && !o_tty_closing))
1713                 return;
1714
1715 #ifdef TTY_DEBUG_HANGUP
1716         printk(KERN_DEBUG "freeing tty structure...");
1717 #endif
1718         /*
1719          * Ask the line discipline code to release its structures
1720          */
1721         tty_ldisc_release(tty, o_tty);
1722         /*
1723          * The release_tty function takes care of the details of clearing
1724          * the slots and preserving the termios structure.
1725          */
1726         release_tty(tty, idx);
1727
1728         /* Make this pty number available for reallocation */
1729         if (devpts)
1730                 devpts_kill_index(inode, idx);
1731 }
1732
1733 /**
1734  *      __tty_open              -       open a tty device
1735  *      @inode: inode of device file
1736  *      @filp: file pointer to tty
1737  *
1738  *      tty_open and tty_release keep up the tty count that contains the
1739  *      number of opens done on a tty. We cannot use the inode-count, as
1740  *      different inodes might point to the same tty.
1741  *
1742  *      Open-counting is needed for pty masters, as well as for keeping
1743  *      track of serial lines: DTR is dropped when the last close happens.
1744  *      (This is not done solely through tty->count, now.  - Ted 1/27/92)
1745  *
1746  *      The termios state of a pty is reset on first open so that
1747  *      settings don't persist across reuse.
1748  *
1749  *      Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
1750  *               tty->count should protect the rest.
1751  *               ->siglock protects ->signal/->sighand
1752  */
1753
1754 static int __tty_open(struct inode *inode, struct file *filp)
1755 {
1756         struct tty_struct *tty = NULL;
1757         int noctty, retval;
1758         struct tty_driver *driver;
1759         int index;
1760         dev_t device = inode->i_rdev;
1761         unsigned short saved_flags = filp->f_flags;
1762
1763         nonseekable_open(inode, filp);
1764
1765 retry_open:
1766         noctty = filp->f_flags & O_NOCTTY;
1767         index  = -1;
1768         retval = 0;
1769
1770         mutex_lock(&tty_mutex);
1771
1772         if (device == MKDEV(TTYAUX_MAJOR, 0)) {
1773                 tty = get_current_tty();
1774                 if (!tty) {
1775                         mutex_unlock(&tty_mutex);
1776                         return -ENXIO;
1777                 }
1778                 driver = tty_driver_kref_get(tty->driver);
1779                 index = tty->index;
1780                 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1781                 /* noctty = 1; */
1782                 /* FIXME: Should we take a driver reference ? */
1783                 tty_kref_put(tty);
1784                 goto got_driver;
1785         }
1786 #ifdef CONFIG_VT
1787         if (device == MKDEV(TTY_MAJOR, 0)) {
1788                 extern struct tty_driver *console_driver;
1789                 driver = tty_driver_kref_get(console_driver);
1790                 index = fg_console;
1791                 noctty = 1;
1792                 goto got_driver;
1793         }
1794 #endif
1795         if (device == MKDEV(TTYAUX_MAJOR, 1)) {
1796                 struct tty_driver *console_driver = console_device(&index);
1797                 if (console_driver) {
1798                         driver = tty_driver_kref_get(console_driver);
1799                         if (driver) {
1800                                 /* Don't let /dev/console block */
1801                                 filp->f_flags |= O_NONBLOCK;
1802                                 noctty = 1;
1803                                 goto got_driver;
1804                         }
1805                 }
1806                 mutex_unlock(&tty_mutex);
1807                 return -ENODEV;
1808         }
1809
1810         driver = get_tty_driver(device, &index);
1811         if (!driver) {
1812                 mutex_unlock(&tty_mutex);
1813                 return -ENODEV;
1814         }
1815 got_driver:
1816         if (!tty) {
1817                 /* check whether we're reopening an existing tty */
1818                 tty = tty_driver_lookup_tty(driver, inode, index);
1819
1820                 if (IS_ERR(tty)) {
1821                         mutex_unlock(&tty_mutex);
1822                         return PTR_ERR(tty);
1823                 }
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  *      @rows: rows (character)
2054  *      @cols: cols (character)
2055  *
2056  *      Update the termios variables and send the neccessary signals to
2057  *      peform a terminal resize correctly
2058  */
2059
2060 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2061 {
2062         struct pid *pgrp;
2063         unsigned long flags;
2064
2065         /* Lock the tty */
2066         mutex_lock(&tty->termios_mutex);
2067         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2068                 goto done;
2069         /* Get the PID values and reference them so we can
2070            avoid holding the tty ctrl lock while sending signals */
2071         spin_lock_irqsave(&tty->ctrl_lock, flags);
2072         pgrp = get_pid(tty->pgrp);
2073         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2074
2075         if (pgrp)
2076                 kill_pgrp(pgrp, SIGWINCH, 1);
2077         put_pid(pgrp);
2078
2079         tty->winsize = *ws;
2080 done:
2081         mutex_unlock(&tty->termios_mutex);
2082         return 0;
2083 }
2084
2085 /**
2086  *      tiocswinsz              -       implement window size set ioctl
2087  *      @tty; tty side of tty
2088  *      @arg: user buffer for result
2089  *
2090  *      Copies the user idea of the window size to the kernel. Traditionally
2091  *      this is just advisory information but for the Linux console it
2092  *      actually has driver level meaning and triggers a VC resize.
2093  *
2094  *      Locking:
2095  *              Driver dependant. The default do_resize method takes the
2096  *      tty termios mutex and ctrl_lock. The console takes its own lock
2097  *      then calls into the default method.
2098  */
2099
2100 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2101 {
2102         struct winsize tmp_ws;
2103         if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2104                 return -EFAULT;
2105
2106         if (tty->ops->resize)
2107                 return tty->ops->resize(tty, &tmp_ws);
2108         else
2109                 return tty_do_resize(tty, &tmp_ws);
2110 }
2111
2112 /**
2113  *      tioccons        -       allow admin to move logical console
2114  *      @file: the file to become console
2115  *
2116  *      Allow the adminstrator to move the redirected console device
2117  *
2118  *      Locking: uses redirect_lock to guard the redirect information
2119  */
2120
2121 static int tioccons(struct file *file)
2122 {
2123         if (!capable(CAP_SYS_ADMIN))
2124                 return -EPERM;
2125         if (file->f_op->write == redirected_tty_write) {
2126                 struct file *f;
2127                 spin_lock(&redirect_lock);
2128                 f = redirect;
2129                 redirect = NULL;
2130                 spin_unlock(&redirect_lock);
2131                 if (f)
2132                         fput(f);
2133                 return 0;
2134         }
2135         spin_lock(&redirect_lock);
2136         if (redirect) {
2137                 spin_unlock(&redirect_lock);
2138                 return -EBUSY;
2139         }
2140         get_file(file);
2141         redirect = file;
2142         spin_unlock(&redirect_lock);
2143         return 0;
2144 }
2145
2146 /**
2147  *      fionbio         -       non blocking ioctl
2148  *      @file: file to set blocking value
2149  *      @p: user parameter
2150  *
2151  *      Historical tty interfaces had a blocking control ioctl before
2152  *      the generic functionality existed. This piece of history is preserved
2153  *      in the expected tty API of posix OS's.
2154  *
2155  *      Locking: none, the open fle handle ensures it won't go away.
2156  */
2157
2158 static int fionbio(struct file *file, int __user *p)
2159 {
2160         int nonblock;
2161
2162         if (get_user(nonblock, p))
2163                 return -EFAULT;
2164
2165         /* file->f_flags is still BKL protected in the fs layer - vomit */
2166         lock_kernel();
2167         if (nonblock)
2168                 file->f_flags |= O_NONBLOCK;
2169         else
2170                 file->f_flags &= ~O_NONBLOCK;
2171         unlock_kernel();
2172         return 0;
2173 }
2174
2175 /**
2176  *      tiocsctty       -       set controlling tty
2177  *      @tty: tty structure
2178  *      @arg: user argument
2179  *
2180  *      This ioctl is used to manage job control. It permits a session
2181  *      leader to set this tty as the controlling tty for the session.
2182  *
2183  *      Locking:
2184  *              Takes tty_mutex() to protect tty instance
2185  *              Takes tasklist_lock internally to walk sessions
2186  *              Takes ->siglock() when updating signal->tty
2187  */
2188
2189 static int tiocsctty(struct tty_struct *tty, int arg)
2190 {
2191         int ret = 0;
2192         if (current->signal->leader && (task_session(current) == tty->session))
2193                 return ret;
2194
2195         mutex_lock(&tty_mutex);
2196         /*
2197          * The process must be a session leader and
2198          * not have a controlling tty already.
2199          */
2200         if (!current->signal->leader || current->signal->tty) {
2201                 ret = -EPERM;
2202                 goto unlock;
2203         }
2204
2205         if (tty->session) {
2206                 /*
2207                  * This tty is already the controlling
2208                  * tty for another session group!
2209                  */
2210                 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2211                         /*
2212                          * Steal it away
2213                          */
2214                         read_lock(&tasklist_lock);
2215                         session_clear_tty(tty->session);
2216                         read_unlock(&tasklist_lock);
2217                 } else {
2218                         ret = -EPERM;
2219                         goto unlock;
2220                 }
2221         }
2222         proc_set_tty(current, tty);
2223 unlock:
2224         mutex_unlock(&tty_mutex);
2225         return ret;
2226 }
2227
2228 /**
2229  *      tty_get_pgrp    -       return a ref counted pgrp pid
2230  *      @tty: tty to read
2231  *
2232  *      Returns a refcounted instance of the pid struct for the process
2233  *      group controlling the tty.
2234  */
2235
2236 struct pid *tty_get_pgrp(struct tty_struct *tty)
2237 {
2238         unsigned long flags;
2239         struct pid *pgrp;
2240
2241         spin_lock_irqsave(&tty->ctrl_lock, flags);
2242         pgrp = get_pid(tty->pgrp);
2243         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2244
2245         return pgrp;
2246 }
2247 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2248
2249 /**
2250  *      tiocgpgrp               -       get process group
2251  *      @tty: tty passed by user
2252  *      @real_tty: tty side of the tty pased by the user if a pty else the tty
2253  *      @p: returned pid
2254  *
2255  *      Obtain the process group of the tty. If there is no process group
2256  *      return an error.
2257  *
2258  *      Locking: none. Reference to current->signal->tty is safe.
2259  */
2260
2261 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2262 {
2263         struct pid *pid;
2264         int ret;
2265         /*
2266          * (tty == real_tty) is a cheap way of
2267          * testing if the tty is NOT a master pty.
2268          */
2269         if (tty == real_tty && current->signal->tty != real_tty)
2270                 return -ENOTTY;
2271         pid = tty_get_pgrp(real_tty);
2272         ret =  put_user(pid_vnr(pid), p);
2273         put_pid(pid);
2274         return ret;
2275 }
2276
2277 /**
2278  *      tiocspgrp               -       attempt to set process group
2279  *      @tty: tty passed by user
2280  *      @real_tty: tty side device matching tty passed by user
2281  *      @p: pid pointer
2282  *
2283  *      Set the process group of the tty to the session passed. Only
2284  *      permitted where the tty session is our session.
2285  *
2286  *      Locking: RCU, ctrl lock
2287  */
2288
2289 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2290 {
2291         struct pid *pgrp;
2292         pid_t pgrp_nr;
2293         int retval = tty_check_change(real_tty);
2294         unsigned long flags;
2295
2296         if (retval == -EIO)
2297                 return -ENOTTY;
2298         if (retval)
2299                 return retval;
2300         if (!current->signal->tty ||
2301             (current->signal->tty != real_tty) ||
2302             (real_tty->session != task_session(current)))
2303                 return -ENOTTY;
2304         if (get_user(pgrp_nr, p))
2305                 return -EFAULT;
2306         if (pgrp_nr < 0)
2307                 return -EINVAL;
2308         rcu_read_lock();
2309         pgrp = find_vpid(pgrp_nr);
2310         retval = -ESRCH;
2311         if (!pgrp)
2312                 goto out_unlock;
2313         retval = -EPERM;
2314         if (session_of_pgrp(pgrp) != task_session(current))
2315                 goto out_unlock;
2316         retval = 0;
2317         spin_lock_irqsave(&tty->ctrl_lock, flags);
2318         put_pid(real_tty->pgrp);
2319         real_tty->pgrp = get_pid(pgrp);
2320         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2321 out_unlock:
2322         rcu_read_unlock();
2323         return retval;
2324 }
2325
2326 /**
2327  *      tiocgsid                -       get session id
2328  *      @tty: tty passed by user
2329  *      @real_tty: tty side of the tty pased by the user if a pty else the tty
2330  *      @p: pointer to returned session id
2331  *
2332  *      Obtain the session id of the tty. If there is no session
2333  *      return an error.
2334  *
2335  *      Locking: none. Reference to current->signal->tty is safe.
2336  */
2337
2338 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2339 {
2340         /*
2341          * (tty == real_tty) is a cheap way of
2342          * testing if the tty is NOT a master pty.
2343         */
2344         if (tty == real_tty && current->signal->tty != real_tty)
2345                 return -ENOTTY;
2346         if (!real_tty->session)
2347                 return -ENOTTY;
2348         return put_user(pid_vnr(real_tty->session), p);
2349 }
2350
2351 /**
2352  *      tiocsetd        -       set line discipline
2353  *      @tty: tty device
2354  *      @p: pointer to user data
2355  *
2356  *      Set the line discipline according to user request.
2357  *
2358  *      Locking: see tty_set_ldisc, this function is just a helper
2359  */
2360
2361 static int tiocsetd(struct tty_struct *tty, int __user *p)
2362 {
2363         int ldisc;
2364         int ret;
2365
2366         if (get_user(ldisc, p))
2367                 return -EFAULT;
2368
2369         lock_kernel();
2370         ret = tty_set_ldisc(tty, ldisc);
2371         unlock_kernel();
2372
2373         return ret;
2374 }
2375
2376 /**
2377  *      send_break      -       performed time break
2378  *      @tty: device to break on
2379  *      @duration: timeout in mS
2380  *
2381  *      Perform a timed break on hardware that lacks its own driver level
2382  *      timed break functionality.
2383  *
2384  *      Locking:
2385  *              atomic_write_lock serializes
2386  *
2387  */
2388
2389 static int send_break(struct tty_struct *tty, unsigned int duration)
2390 {
2391         int retval;
2392
2393         if (tty->ops->break_ctl == NULL)
2394                 return 0;
2395
2396         if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2397                 retval = tty->ops->break_ctl(tty, duration);
2398         else {
2399                 /* Do the work ourselves */
2400                 if (tty_write_lock(tty, 0) < 0)
2401                         return -EINTR;
2402                 retval = tty->ops->break_ctl(tty, -1);
2403                 if (retval)
2404                         goto out;
2405                 if (!signal_pending(current))
2406                         msleep_interruptible(duration);
2407                 retval = tty->ops->break_ctl(tty, 0);
2408 out:
2409                 tty_write_unlock(tty);
2410                 if (signal_pending(current))
2411                         retval = -EINTR;
2412         }
2413         return retval;
2414 }
2415
2416 /**
2417  *      tty_tiocmget            -       get modem status
2418  *      @tty: tty device
2419  *      @file: user file pointer
2420  *      @p: pointer to result
2421  *
2422  *      Obtain the modem status bits from the tty driver if the feature
2423  *      is supported. Return -EINVAL if it is not available.
2424  *
2425  *      Locking: none (up to the driver)
2426  */
2427
2428 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
2429 {
2430         int retval = -EINVAL;
2431
2432         if (tty->ops->tiocmget) {
2433                 retval = tty->ops->tiocmget(tty, file);
2434
2435                 if (retval >= 0)
2436                         retval = put_user(retval, p);
2437         }
2438         return retval;
2439 }
2440
2441 /**
2442  *      tty_tiocmset            -       set modem status
2443  *      @tty: tty device
2444  *      @file: user file pointer
2445  *      @cmd: command - clear bits, set bits or set all
2446  *      @p: pointer to desired bits
2447  *
2448  *      Set the modem status bits from the tty driver if the feature
2449  *      is supported. Return -EINVAL if it is not available.
2450  *
2451  *      Locking: none (up to the driver)
2452  */
2453
2454 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
2455              unsigned __user *p)
2456 {
2457         int retval;
2458         unsigned int set, clear, val;
2459
2460         if (tty->ops->tiocmset == NULL)
2461                 return -EINVAL;
2462
2463         retval = get_user(val, p);
2464         if (retval)
2465                 return retval;
2466         set = clear = 0;
2467         switch (cmd) {
2468         case TIOCMBIS:
2469                 set = val;
2470                 break;
2471         case TIOCMBIC:
2472                 clear = val;
2473                 break;
2474         case TIOCMSET:
2475                 set = val;
2476                 clear = ~val;
2477                 break;
2478         }
2479         set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2480         clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2481         return tty->ops->tiocmset(tty, file, set, clear);
2482 }
2483
2484 /*
2485  * Split this up, as gcc can choke on it otherwise..
2486  */
2487 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2488 {
2489         struct tty_struct *tty, *real_tty;
2490         void __user *p = (void __user *)arg;
2491         int retval;
2492         struct tty_ldisc *ld;
2493         struct inode *inode = file->f_dentry->d_inode;
2494
2495         tty = (struct tty_struct *)file->private_data;
2496         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2497                 return -EINVAL;
2498
2499         real_tty = tty;
2500         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2501             tty->driver->subtype == PTY_TYPE_MASTER)
2502                 real_tty = tty->link;
2503
2504
2505         /*
2506          * Factor out some common prep work
2507          */
2508         switch (cmd) {
2509         case TIOCSETD:
2510         case TIOCSBRK:
2511         case TIOCCBRK:
2512         case TCSBRK:
2513         case TCSBRKP:
2514                 retval = tty_check_change(tty);
2515                 if (retval)
2516                         return retval;
2517                 if (cmd != TIOCCBRK) {
2518                         tty_wait_until_sent(tty, 0);
2519                         if (signal_pending(current))
2520                                 return -EINTR;
2521                 }
2522                 break;
2523         }
2524
2525         /*
2526          *      Now do the stuff.
2527          */
2528         switch (cmd) {
2529         case TIOCSTI:
2530                 return tiocsti(tty, p);
2531         case TIOCGWINSZ:
2532                 return tiocgwinsz(real_tty, p);
2533         case TIOCSWINSZ:
2534                 return tiocswinsz(real_tty, p);
2535         case TIOCCONS:
2536                 return real_tty != tty ? -EINVAL : tioccons(file);
2537         case FIONBIO:
2538                 return fionbio(file, p);
2539         case TIOCEXCL:
2540                 set_bit(TTY_EXCLUSIVE, &tty->flags);
2541                 return 0;
2542         case TIOCNXCL:
2543                 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2544                 return 0;
2545         case TIOCNOTTY:
2546                 if (current->signal->tty != tty)
2547                         return -ENOTTY;
2548                 no_tty();
2549                 return 0;
2550         case TIOCSCTTY:
2551                 return tiocsctty(tty, arg);
2552         case TIOCGPGRP:
2553                 return tiocgpgrp(tty, real_tty, p);
2554         case TIOCSPGRP:
2555                 return tiocspgrp(tty, real_tty, p);
2556         case TIOCGSID:
2557                 return tiocgsid(tty, real_tty, p);
2558         case TIOCGETD:
2559                 return put_user(tty->ldisc.ops->num, (int __user *)p);
2560         case TIOCSETD:
2561                 return tiocsetd(tty, p);
2562         /*
2563          * Break handling
2564          */
2565         case TIOCSBRK:  /* Turn break on, unconditionally */
2566                 if (tty->ops->break_ctl)
2567                         return tty->ops->break_ctl(tty, -1);
2568                 return 0;
2569         case TIOCCBRK:  /* Turn break off, unconditionally */
2570                 if (tty->ops->break_ctl)
2571                         return tty->ops->break_ctl(tty, 0);
2572                 return 0;
2573         case TCSBRK:   /* SVID version: non-zero arg --> no break */
2574                 /* non-zero arg means wait for all output data
2575                  * to be sent (performed above) but don't send break.
2576                  * This is used by the tcdrain() termios function.
2577                  */
2578                 if (!arg)
2579                         return send_break(tty, 250);
2580                 return 0;
2581         case TCSBRKP:   /* support for POSIX tcsendbreak() */
2582                 return send_break(tty, arg ? arg*100 : 250);
2583
2584         case TIOCMGET:
2585                 return tty_tiocmget(tty, file, p);
2586         case TIOCMSET:
2587         case TIOCMBIC:
2588         case TIOCMBIS:
2589                 return tty_tiocmset(tty, file, cmd, p);
2590         case TCFLSH:
2591                 switch (arg) {
2592                 case TCIFLUSH:
2593                 case TCIOFLUSH:
2594                 /* flush tty buffer and allow ldisc to process ioctl */
2595                         tty_buffer_flush(tty);
2596                         break;
2597                 }
2598                 break;
2599         }
2600         if (tty->ops->ioctl) {
2601                 retval = (tty->ops->ioctl)(tty, file, cmd, arg);
2602                 if (retval != -ENOIOCTLCMD)
2603                         return retval;
2604         }
2605         ld = tty_ldisc_ref_wait(tty);
2606         retval = -EINVAL;
2607         if (ld->ops->ioctl) {
2608                 retval = ld->ops->ioctl(tty, file, cmd, arg);
2609                 if (retval == -ENOIOCTLCMD)
2610                         retval = -EINVAL;
2611         }
2612         tty_ldisc_deref(ld);
2613         return retval;
2614 }
2615
2616 #ifdef CONFIG_COMPAT
2617 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2618                                 unsigned long arg)
2619 {
2620         struct inode *inode = file->f_dentry->d_inode;
2621         struct tty_struct *tty = file->private_data;
2622         struct tty_ldisc *ld;
2623         int retval = -ENOIOCTLCMD;
2624
2625         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2626                 return -EINVAL;
2627
2628         if (tty->ops->compat_ioctl) {
2629                 retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
2630                 if (retval != -ENOIOCTLCMD)
2631                         return retval;
2632         }
2633
2634         ld = tty_ldisc_ref_wait(tty);
2635         if (ld->ops->compat_ioctl)
2636                 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2637         tty_ldisc_deref(ld);
2638
2639         return retval;
2640 }
2641 #endif
2642
2643 /*
2644  * This implements the "Secure Attention Key" ---  the idea is to
2645  * prevent trojan horses by killing all processes associated with this
2646  * tty when the user hits the "Secure Attention Key".  Required for
2647  * super-paranoid applications --- see the Orange Book for more details.
2648  *
2649  * This code could be nicer; ideally it should send a HUP, wait a few
2650  * seconds, then send a INT, and then a KILL signal.  But you then
2651  * have to coordinate with the init process, since all processes associated
2652  * with the current tty must be dead before the new getty is allowed
2653  * to spawn.
2654  *
2655  * Now, if it would be correct ;-/ The current code has a nasty hole -
2656  * it doesn't catch files in flight. We may send the descriptor to ourselves
2657  * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2658  *
2659  * Nasty bug: do_SAK is being called in interrupt context.  This can
2660  * deadlock.  We punt it up to process context.  AKPM - 16Mar2001
2661  */
2662 void __do_SAK(struct tty_struct *tty)
2663 {
2664 #ifdef TTY_SOFT_SAK
2665         tty_hangup(tty);
2666 #else
2667         struct task_struct *g, *p;
2668         struct pid *session;
2669         int             i;
2670         struct file     *filp;
2671         struct fdtable *fdt;
2672
2673         if (!tty)
2674                 return;
2675         session = tty->session;
2676
2677         tty_ldisc_flush(tty);
2678
2679         tty_driver_flush_buffer(tty);
2680
2681         read_lock(&tasklist_lock);
2682         /* Kill the entire session */
2683         do_each_pid_task(session, PIDTYPE_SID, p) {
2684                 printk(KERN_NOTICE "SAK: killed process %d"
2685                         " (%s): task_session_nr(p)==tty->session\n",
2686                         task_pid_nr(p), p->comm);
2687                 send_sig(SIGKILL, p, 1);
2688         } while_each_pid_task(session, PIDTYPE_SID, p);
2689         /* Now kill any processes that happen to have the
2690          * tty open.
2691          */
2692         do_each_thread(g, p) {
2693                 if (p->signal->tty == tty) {
2694                         printk(KERN_NOTICE "SAK: killed process %d"
2695                             " (%s): task_session_nr(p)==tty->session\n",
2696                             task_pid_nr(p), p->comm);
2697                         send_sig(SIGKILL, p, 1);
2698                         continue;
2699                 }
2700                 task_lock(p);
2701                 if (p->files) {
2702                         /*
2703                          * We don't take a ref to the file, so we must
2704                          * hold ->file_lock instead.
2705                          */
2706                         spin_lock(&p->files->file_lock);
2707                         fdt = files_fdtable(p->files);
2708                         for (i = 0; i < fdt->max_fds; i++) {
2709                                 filp = fcheck_files(p->files, i);
2710                                 if (!filp)
2711                                         continue;
2712                                 if (filp->f_op->read == tty_read &&
2713                                     filp->private_data == tty) {
2714                                         printk(KERN_NOTICE "SAK: killed process %d"
2715                                             " (%s): fd#%d opened to the tty\n",
2716                                             task_pid_nr(p), p->comm, i);
2717                                         force_sig(SIGKILL, p);
2718                                         break;
2719                                 }
2720                         }
2721                         spin_unlock(&p->files->file_lock);
2722                 }
2723                 task_unlock(p);
2724         } while_each_thread(g, p);
2725         read_unlock(&tasklist_lock);
2726 #endif
2727 }
2728
2729 static void do_SAK_work(struct work_struct *work)
2730 {
2731         struct tty_struct *tty =
2732                 container_of(work, struct tty_struct, SAK_work);
2733         __do_SAK(tty);
2734 }
2735
2736 /*
2737  * The tq handling here is a little racy - tty->SAK_work may already be queued.
2738  * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2739  * the values which we write to it will be identical to the values which it
2740  * already has. --akpm
2741  */
2742 void do_SAK(struct tty_struct *tty)
2743 {
2744         if (!tty)
2745                 return;
2746         schedule_work(&tty->SAK_work);
2747 }
2748
2749 EXPORT_SYMBOL(do_SAK);
2750
2751 /**
2752  *      initialize_tty_struct
2753  *      @tty: tty to initialize
2754  *
2755  *      This subroutine initializes a tty structure that has been newly
2756  *      allocated.
2757  *
2758  *      Locking: none - tty in question must not be exposed at this point
2759  */
2760
2761 void initialize_tty_struct(struct tty_struct *tty,
2762                 struct tty_driver *driver, int idx)
2763 {
2764         memset(tty, 0, sizeof(struct tty_struct));
2765         kref_init(&tty->kref);
2766         tty->magic = TTY_MAGIC;
2767         tty_ldisc_init(tty);
2768         tty->session = NULL;
2769         tty->pgrp = NULL;
2770         tty->overrun_time = jiffies;
2771         tty->buf.head = tty->buf.tail = NULL;
2772         tty_buffer_init(tty);
2773         mutex_init(&tty->termios_mutex);
2774         init_waitqueue_head(&tty->write_wait);
2775         init_waitqueue_head(&tty->read_wait);
2776         INIT_WORK(&tty->hangup_work, do_tty_hangup);
2777         mutex_init(&tty->atomic_read_lock);
2778         mutex_init(&tty->atomic_write_lock);
2779         mutex_init(&tty->output_lock);
2780         mutex_init(&tty->echo_lock);
2781         spin_lock_init(&tty->read_lock);
2782         spin_lock_init(&tty->ctrl_lock);
2783         INIT_LIST_HEAD(&tty->tty_files);
2784         INIT_WORK(&tty->SAK_work, do_SAK_work);
2785
2786         tty->driver = driver;
2787         tty->ops = driver->ops;
2788         tty->index = idx;
2789         tty_line_name(driver, idx, tty->name);
2790 }
2791
2792 /**
2793  *      tty_put_char    -       write one character to a tty
2794  *      @tty: tty
2795  *      @ch: character
2796  *
2797  *      Write one byte to the tty using the provided put_char method
2798  *      if present. Returns the number of characters successfully output.
2799  *
2800  *      Note: the specific put_char operation in the driver layer may go
2801  *      away soon. Don't call it directly, use this method
2802  */
2803
2804 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2805 {
2806         if (tty->ops->put_char)
2807                 return tty->ops->put_char(tty, ch);
2808         return tty->ops->write(tty, &ch, 1);
2809 }
2810 EXPORT_SYMBOL_GPL(tty_put_char);
2811
2812 struct class *tty_class;
2813
2814 /**
2815  *      tty_register_device - register a tty device
2816  *      @driver: the tty driver that describes the tty device
2817  *      @index: the index in the tty driver for this tty device
2818  *      @device: a struct device that is associated with this tty device.
2819  *              This field is optional, if there is no known struct device
2820  *              for this tty device it can be set to NULL safely.
2821  *
2822  *      Returns a pointer to the struct device for this tty device
2823  *      (or ERR_PTR(-EFOO) on error).
2824  *
2825  *      This call is required to be made to register an individual tty device
2826  *      if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set.  If
2827  *      that bit is not set, this function should not be called by a tty
2828  *      driver.
2829  *
2830  *      Locking: ??
2831  */
2832
2833 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2834                                    struct device *device)
2835 {
2836         char name[64];
2837         dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
2838
2839         if (index >= driver->num) {
2840                 printk(KERN_ERR "Attempt to register invalid tty line number "
2841                        " (%d).\n", index);
2842                 return ERR_PTR(-EINVAL);
2843         }
2844
2845         if (driver->type == TTY_DRIVER_TYPE_PTY)
2846                 pty_line_name(driver, index, name);
2847         else
2848                 tty_line_name(driver, index, name);
2849
2850         return device_create(tty_class, device, dev, NULL, name);
2851 }
2852 EXPORT_SYMBOL(tty_register_device);
2853
2854 /**
2855  *      tty_unregister_device - unregister a tty device
2856  *      @driver: the tty driver that describes the tty device
2857  *      @index: the index in the tty driver for this tty device
2858  *
2859  *      If a tty device is registered with a call to tty_register_device() then
2860  *      this function must be called when the tty device is gone.
2861  *
2862  *      Locking: ??
2863  */
2864
2865 void tty_unregister_device(struct tty_driver *driver, unsigned index)
2866 {
2867         device_destroy(tty_class,
2868                 MKDEV(driver->major, driver->minor_start) + index);
2869 }
2870 EXPORT_SYMBOL(tty_unregister_device);
2871
2872 struct tty_driver *alloc_tty_driver(int lines)
2873 {
2874         struct tty_driver *driver;
2875
2876         driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
2877         if (driver) {
2878                 kref_init(&driver->kref);
2879                 driver->magic = TTY_DRIVER_MAGIC;
2880                 driver->num = lines;
2881                 /* later we'll move allocation of tables here */
2882         }
2883         return driver;
2884 }
2885 EXPORT_SYMBOL(alloc_tty_driver);
2886
2887 static void destruct_tty_driver(struct kref *kref)
2888 {
2889         struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
2890         int i;
2891         struct ktermios *tp;
2892         void *p;
2893
2894         if (driver->flags & TTY_DRIVER_INSTALLED) {
2895                 /*
2896                  * Free the termios and termios_locked structures because
2897                  * we don't want to get memory leaks when modular tty
2898                  * drivers are removed from the kernel.
2899                  */
2900                 for (i = 0; i < driver->num; i++) {
2901                         tp = driver->termios[i];
2902                         if (tp) {
2903                                 driver->termios[i] = NULL;
2904                                 kfree(tp);
2905                         }
2906                         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
2907                                 tty_unregister_device(driver, i);
2908                 }
2909                 p = driver->ttys;
2910                 proc_tty_unregister_driver(driver);
2911                 driver->ttys = NULL;
2912                 driver->termios = NULL;
2913                 kfree(p);
2914                 cdev_del(&driver->cdev);
2915         }
2916         kfree(driver);
2917 }
2918
2919 void tty_driver_kref_put(struct tty_driver *driver)
2920 {
2921         kref_put(&driver->kref, destruct_tty_driver);
2922 }
2923 EXPORT_SYMBOL(tty_driver_kref_put);
2924
2925 void tty_set_operations(struct tty_driver *driver,
2926                         const struct tty_operations *op)
2927 {
2928         driver->ops = op;
2929 };
2930 EXPORT_SYMBOL(tty_set_operations);
2931
2932 void put_tty_driver(struct tty_driver *d)
2933 {
2934         tty_driver_kref_put(d);
2935 }
2936 EXPORT_SYMBOL(put_tty_driver);
2937
2938 /*
2939  * Called by a tty driver to register itself.
2940  */
2941 int tty_register_driver(struct tty_driver *driver)
2942 {
2943         int error;
2944         int i;
2945         dev_t dev;
2946         void **p = NULL;
2947
2948         if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
2949                 p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
2950                 if (!p)
2951                         return -ENOMEM;
2952         }
2953
2954         if (!driver->major) {
2955                 error = alloc_chrdev_region(&dev, driver->minor_start,
2956                                                 driver->num, driver->name);
2957                 if (!error) {
2958                         driver->major = MAJOR(dev);
2959                         driver->minor_start = MINOR(dev);
2960                 }
2961         } else {
2962                 dev = MKDEV(driver->major, driver->minor_start);
2963                 error = register_chrdev_region(dev, driver->num, driver->name);
2964         }
2965         if (error < 0) {
2966                 kfree(p);
2967                 return error;
2968         }
2969
2970         if (p) {
2971                 driver->ttys = (struct tty_struct **)p;
2972                 driver->termios = (struct ktermios **)(p + driver->num);
2973         } else {
2974                 driver->ttys = NULL;
2975                 driver->termios = NULL;
2976         }
2977
2978         cdev_init(&driver->cdev, &tty_fops);
2979         driver->cdev.owner = driver->owner;
2980         error = cdev_add(&driver->cdev, dev, driver->num);
2981         if (error) {
2982                 unregister_chrdev_region(dev, driver->num);
2983                 driver->ttys = NULL;
2984                 driver->termios = NULL;
2985                 kfree(p);
2986                 return error;
2987         }
2988
2989         mutex_lock(&tty_mutex);
2990         list_add(&driver->tty_drivers, &tty_drivers);
2991         mutex_unlock(&tty_mutex);
2992
2993         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
2994                 for (i = 0; i < driver->num; i++)
2995                     tty_register_device(driver, i, NULL);
2996         }
2997         proc_tty_register_driver(driver);
2998         driver->flags |= TTY_DRIVER_INSTALLED;
2999         return 0;
3000 }
3001
3002 EXPORT_SYMBOL(tty_register_driver);
3003
3004 /*
3005  * Called by a tty driver to unregister itself.
3006  */
3007 int tty_unregister_driver(struct tty_driver *driver)
3008 {
3009 #if 0
3010         /* FIXME */
3011         if (driver->refcount)
3012                 return -EBUSY;
3013 #endif
3014         unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3015                                 driver->num);
3016         mutex_lock(&tty_mutex);
3017         list_del(&driver->tty_drivers);
3018         mutex_unlock(&tty_mutex);
3019         return 0;
3020 }
3021
3022 EXPORT_SYMBOL(tty_unregister_driver);
3023
3024 dev_t tty_devnum(struct tty_struct *tty)
3025 {
3026         return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3027 }
3028 EXPORT_SYMBOL(tty_devnum);
3029
3030 void proc_clear_tty(struct task_struct *p)
3031 {
3032         unsigned long flags;
3033         struct tty_struct *tty;
3034         spin_lock_irqsave(&p->sighand->siglock, flags);
3035         tty = p->signal->tty;
3036         p->signal->tty = NULL;
3037         spin_unlock_irqrestore(&p->sighand->siglock, flags);
3038         tty_kref_put(tty);
3039 }
3040
3041 /* Called under the sighand lock */
3042
3043 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3044 {
3045         if (tty) {
3046                 unsigned long flags;
3047                 /* We should not have a session or pgrp to put here but.... */
3048                 spin_lock_irqsave(&tty->ctrl_lock, flags);
3049                 put_pid(tty->session);
3050                 put_pid(tty->pgrp);
3051                 tty->pgrp = get_pid(task_pgrp(tsk));
3052                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3053                 tty->session = get_pid(task_session(tsk));
3054                 if (tsk->signal->tty) {
3055                         printk(KERN_DEBUG "tty not NULL!!\n");
3056                         tty_kref_put(tsk->signal->tty);
3057                 }
3058         }
3059         put_pid(tsk->signal->tty_old_pgrp);
3060         tsk->signal->tty = tty_kref_get(tty);
3061         tsk->signal->tty_old_pgrp = NULL;
3062 }
3063
3064 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3065 {
3066         spin_lock_irq(&tsk->sighand->siglock);
3067         __proc_set_tty(tsk, tty);
3068         spin_unlock_irq(&tsk->sighand->siglock);
3069 }
3070
3071 struct tty_struct *get_current_tty(void)
3072 {
3073         struct tty_struct *tty;
3074         unsigned long flags;
3075
3076         spin_lock_irqsave(&current->sighand->siglock, flags);
3077         tty = tty_kref_get(current->signal->tty);
3078         spin_unlock_irqrestore(&current->sighand->siglock, flags);
3079         return tty;
3080 }
3081 EXPORT_SYMBOL_GPL(get_current_tty);
3082
3083 void tty_default_fops(struct file_operations *fops)
3084 {
3085         *fops = tty_fops;
3086 }
3087
3088 /*
3089  * Initialize the console device. This is called *early*, so
3090  * we can't necessarily depend on lots of kernel help here.
3091  * Just do some early initializations, and do the complex setup
3092  * later.
3093  */
3094 void __init console_init(void)
3095 {
3096         initcall_t *call;
3097
3098         /* Setup the default TTY line discipline. */
3099         tty_ldisc_begin();
3100
3101         /*
3102          * set up the console device so that later boot sequences can
3103          * inform about problems etc..
3104          */
3105         call = __con_initcall_start;
3106         while (call < __con_initcall_end) {
3107                 (*call)();
3108                 call++;
3109         }
3110 }
3111
3112 static int __init tty_class_init(void)
3113 {
3114         tty_class = class_create(THIS_MODULE, "tty");
3115         if (IS_ERR(tty_class))
3116                 return PTR_ERR(tty_class);
3117         return 0;
3118 }
3119
3120 postcore_initcall(tty_class_init);
3121
3122 /* 3/2004 jmc: why do these devices exist? */
3123
3124 static struct cdev tty_cdev, console_cdev;
3125
3126 /*
3127  * Ok, now we can initialize the rest of the tty devices and can count
3128  * on memory allocations, interrupts etc..
3129  */
3130 static int __init tty_init(void)
3131 {
3132         cdev_init(&tty_cdev, &tty_fops);
3133         if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3134             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3135                 panic("Couldn't register /dev/tty driver\n");
3136         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
3137                               "tty");
3138
3139         cdev_init(&console_cdev, &console_fops);
3140         if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3141             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3142                 panic("Couldn't register /dev/console driver\n");
3143         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3144                               "console");
3145
3146 #ifdef CONFIG_VT
3147         vty_init(&console_fops);
3148 #endif
3149         return 0;
3150 }
3151 module_init(tty_init);