a42c466f7092e2f519f8428be2669ab964a56575
[linux-2.6.git] / 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 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
146 #ifdef CONFIG_COMPAT
147 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
148                                 unsigned long arg);
149 #else
150 #define tty_compat_ioctl NULL
151 #endif
152 static int tty_fasync(int fd, struct file *filp, int on);
153 static void release_tty(struct tty_struct *tty, int idx);
154 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
155 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
156
157 /**
158  *      alloc_tty_struct        -       allocate a tty object
159  *
160  *      Return a new empty tty structure. The data fields have not
161  *      been initialized in any way but has been zeroed
162  *
163  *      Locking: none
164  */
165
166 struct tty_struct *alloc_tty_struct(void)
167 {
168         return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
169 }
170
171 /**
172  *      free_tty_struct         -       free a disused tty
173  *      @tty: tty struct to free
174  *
175  *      Free the write buffers, tty queue and tty memory itself.
176  *
177  *      Locking: none. Must be called after tty is definitely unused
178  */
179
180 void free_tty_struct(struct tty_struct *tty)
181 {
182         kfree(tty->write_buf);
183         tty_buffer_free_all(tty);
184         kfree(tty);
185 }
186
187 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
188
189 /**
190  *      tty_name        -       return tty naming
191  *      @tty: tty structure
192  *      @buf: buffer for output
193  *
194  *      Convert a tty structure into a name. The name reflects the kernel
195  *      naming policy and if udev is in use may not reflect user space
196  *
197  *      Locking: none
198  */
199
200 char *tty_name(struct tty_struct *tty, char *buf)
201 {
202         if (!tty) /* Hmm.  NULL pointer.  That's fun. */
203                 strcpy(buf, "NULL tty");
204         else
205                 strcpy(buf, tty->name);
206         return buf;
207 }
208
209 EXPORT_SYMBOL(tty_name);
210
211 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
212                               const char *routine)
213 {
214 #ifdef TTY_PARANOIA_CHECK
215         if (!tty) {
216                 printk(KERN_WARNING
217                         "null TTY for (%d:%d) in %s\n",
218                         imajor(inode), iminor(inode), routine);
219                 return 1;
220         }
221         if (tty->magic != TTY_MAGIC) {
222                 printk(KERN_WARNING
223                         "bad magic number for tty struct (%d:%d) in %s\n",
224                         imajor(inode), iminor(inode), routine);
225                 return 1;
226         }
227 #endif
228         return 0;
229 }
230
231 static int check_tty_count(struct tty_struct *tty, const char *routine)
232 {
233 #ifdef CHECK_TTY_COUNT
234         struct list_head *p;
235         int count = 0;
236
237         file_list_lock();
238         list_for_each(p, &tty->tty_files) {
239                 count++;
240         }
241         file_list_unlock();
242         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
243             tty->driver->subtype == PTY_TYPE_SLAVE &&
244             tty->link && tty->link->count)
245                 count++;
246         if (tty->count != count) {
247                 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
248                                     "!= #fd's(%d) in %s\n",
249                        tty->name, tty->count, count, routine);
250                 return count;
251         }
252 #endif
253         return 0;
254 }
255
256 /**
257  *      get_tty_driver          -       find device of a tty
258  *      @dev_t: device identifier
259  *      @index: returns the index of the tty
260  *
261  *      This routine returns a tty driver structure, given a device number
262  *      and also passes back the index number.
263  *
264  *      Locking: caller must hold tty_mutex
265  */
266
267 static struct tty_driver *get_tty_driver(dev_t device, int *index)
268 {
269         struct tty_driver *p;
270
271         list_for_each_entry(p, &tty_drivers, tty_drivers) {
272                 dev_t base = MKDEV(p->major, p->minor_start);
273                 if (device < base || device >= base + p->num)
274                         continue;
275                 *index = device - base;
276                 return tty_driver_kref_get(p);
277         }
278         return NULL;
279 }
280
281 #ifdef CONFIG_CONSOLE_POLL
282
283 /**
284  *      tty_find_polling_driver -       find device of a polled tty
285  *      @name: name string to match
286  *      @line: pointer to resulting tty line nr
287  *
288  *      This routine returns a tty driver structure, given a name
289  *      and the condition that the tty driver is capable of polled
290  *      operation.
291  */
292 struct tty_driver *tty_find_polling_driver(char *name, int *line)
293 {
294         struct tty_driver *p, *res = NULL;
295         int tty_line = 0;
296         int len;
297         char *str, *stp;
298
299         for (str = name; *str; str++)
300                 if ((*str >= '0' && *str <= '9') || *str == ',')
301                         break;
302         if (!*str)
303                 return NULL;
304
305         len = str - name;
306         tty_line = simple_strtoul(str, &str, 10);
307
308         mutex_lock(&tty_mutex);
309         /* Search through the tty devices to look for a match */
310         list_for_each_entry(p, &tty_drivers, tty_drivers) {
311                 if (strncmp(name, p->name, len) != 0)
312                         continue;
313                 stp = str;
314                 if (*stp == ',')
315                         stp++;
316                 if (*stp == '\0')
317                         stp = 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, stp)) {
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_poll(&tty->write_wait, POLLOUT);
468 }
469
470 EXPORT_SYMBOL_GPL(tty_wakeup);
471
472 /**
473  *      do_tty_hangup           -       actual handler for hangup events
474  *      @work: tty device
475  *
476  *      This can be called by the "eventd" kernel thread.  That is process
477  *      synchronous but doesn't hold any locks, so we need to make sure we
478  *      have the appropriate locks for what we're doing.
479  *
480  *      The hangup event clears any pending redirections onto the hung up
481  *      device. It ensures future writes will error and it does the needed
482  *      line discipline hangup and signal delivery. The tty object itself
483  *      remains intact.
484  *
485  *      Locking:
486  *              BKL
487  *                redirect lock for undoing redirection
488  *                file list lock for manipulating list of ttys
489  *                tty_ldisc_lock from called functions
490  *                termios_mutex resetting termios data
491  *                tasklist_lock to walk task list for hangup event
492  *                  ->siglock to protect ->signal/->sighand
493  */
494 static void do_tty_hangup(struct work_struct *work)
495 {
496         struct tty_struct *tty =
497                 container_of(work, struct tty_struct, hangup_work);
498         struct file *cons_filp = NULL;
499         struct file *filp, *f = NULL;
500         struct task_struct *p;
501         int    closecount = 0, n;
502         unsigned long flags;
503         int refs = 0;
504
505         if (!tty)
506                 return;
507
508
509         spin_lock(&redirect_lock);
510         if (redirect && redirect->private_data == tty) {
511                 f = redirect;
512                 redirect = NULL;
513         }
514         spin_unlock(&redirect_lock);
515
516         /* inuse_filps is protected by the single kernel lock */
517         lock_kernel();
518         check_tty_count(tty, "do_tty_hangup");
519
520         file_list_lock();
521         /* This breaks for file handles being sent over AF_UNIX sockets ? */
522         list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
523                 if (filp->f_op->write == redirected_tty_write)
524                         cons_filp = filp;
525                 if (filp->f_op->write != tty_write)
526                         continue;
527                 closecount++;
528                 tty_fasync(-1, filp, 0);        /* can't block */
529                 filp->f_op = &hung_up_tty_fops;
530         }
531         file_list_unlock();
532
533         tty_ldisc_hangup(tty);
534
535         read_lock(&tasklist_lock);
536         if (tty->session) {
537                 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
538                         spin_lock_irq(&p->sighand->siglock);
539                         if (p->signal->tty == tty) {
540                                 p->signal->tty = NULL;
541                                 /* We defer the dereferences outside fo
542                                    the tasklist lock */
543                                 refs++;
544                         }
545                         if (!p->signal->leader) {
546                                 spin_unlock_irq(&p->sighand->siglock);
547                                 continue;
548                         }
549                         __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
550                         __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
551                         put_pid(p->signal->tty_old_pgrp);  /* A noop */
552                         spin_lock_irqsave(&tty->ctrl_lock, flags);
553                         if (tty->pgrp)
554                                 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
555                         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
556                         spin_unlock_irq(&p->sighand->siglock);
557                 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
558         }
559         read_unlock(&tasklist_lock);
560
561         spin_lock_irqsave(&tty->ctrl_lock, flags);
562         clear_bit(TTY_THROTTLED, &tty->flags);
563         clear_bit(TTY_PUSH, &tty->flags);
564         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
565         put_pid(tty->session);
566         put_pid(tty->pgrp);
567         tty->session = NULL;
568         tty->pgrp = NULL;
569         tty->ctrl_status = 0;
570         set_bit(TTY_HUPPED, &tty->flags);
571         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
572
573         /* Account for the p->signal references we killed */
574         while (refs--)
575                 tty_kref_put(tty);
576
577         /*
578          * If one of the devices matches a console pointer, we
579          * cannot just call hangup() because that will cause
580          * tty->count and state->count to go out of sync.
581          * So we just call close() the right number of times.
582          */
583         if (cons_filp) {
584                 if (tty->ops->close)
585                         for (n = 0; n < closecount; n++)
586                                 tty->ops->close(tty, cons_filp);
587         } else if (tty->ops->hangup)
588                 (tty->ops->hangup)(tty);
589         /*
590          * We don't want to have driver/ldisc interactions beyond
591          * the ones we did here. The driver layer expects no
592          * calls after ->hangup() from the ldisc side. However we
593          * can't yet guarantee all that.
594          */
595         set_bit(TTY_HUPPED, &tty->flags);
596         tty_ldisc_enable(tty);
597         unlock_kernel();
598         if (f)
599                 fput(f);
600 }
601
602 /**
603  *      tty_hangup              -       trigger a hangup event
604  *      @tty: tty to hangup
605  *
606  *      A carrier loss (virtual or otherwise) has occurred on this like
607  *      schedule a hangup sequence to run after this event.
608  */
609
610 void tty_hangup(struct tty_struct *tty)
611 {
612 #ifdef TTY_DEBUG_HANGUP
613         char    buf[64];
614         printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
615 #endif
616         schedule_work(&tty->hangup_work);
617 }
618
619 EXPORT_SYMBOL(tty_hangup);
620
621 /**
622  *      tty_vhangup             -       process vhangup
623  *      @tty: tty to hangup
624  *
625  *      The user has asked via system call for the terminal to be hung up.
626  *      We do this synchronously so that when the syscall returns the process
627  *      is complete. That guarantee is necessary for security reasons.
628  */
629
630 void tty_vhangup(struct tty_struct *tty)
631 {
632 #ifdef TTY_DEBUG_HANGUP
633         char    buf[64];
634
635         printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
636 #endif
637         do_tty_hangup(&tty->hangup_work);
638 }
639
640 EXPORT_SYMBOL(tty_vhangup);
641
642 /**
643  *      tty_vhangup_self        -       process vhangup for own ctty
644  *
645  *      Perform a vhangup on the current controlling tty
646  */
647
648 void tty_vhangup_self(void)
649 {
650         struct tty_struct *tty;
651
652         tty = get_current_tty();
653         if (tty) {
654                 tty_vhangup(tty);
655                 tty_kref_put(tty);
656         }
657 }
658
659 /**
660  *      tty_hung_up_p           -       was tty hung up
661  *      @filp: file pointer of tty
662  *
663  *      Return true if the tty has been subject to a vhangup or a carrier
664  *      loss
665  */
666
667 int tty_hung_up_p(struct file *filp)
668 {
669         return (filp->f_op == &hung_up_tty_fops);
670 }
671
672 EXPORT_SYMBOL(tty_hung_up_p);
673
674 static void session_clear_tty(struct pid *session)
675 {
676         struct task_struct *p;
677         do_each_pid_task(session, PIDTYPE_SID, p) {
678                 proc_clear_tty(p);
679         } while_each_pid_task(session, PIDTYPE_SID, p);
680 }
681
682 /**
683  *      disassociate_ctty       -       disconnect controlling tty
684  *      @on_exit: true if exiting so need to "hang up" the session
685  *
686  *      This function is typically called only by the session leader, when
687  *      it wants to disassociate itself from its controlling tty.
688  *
689  *      It performs the following functions:
690  *      (1)  Sends a SIGHUP and SIGCONT to the foreground process group
691  *      (2)  Clears the tty from being controlling the session
692  *      (3)  Clears the controlling tty for all processes in the
693  *              session group.
694  *
695  *      The argument on_exit is set to 1 if called when a process is
696  *      exiting; it is 0 if called by the ioctl TIOCNOTTY.
697  *
698  *      Locking:
699  *              BKL is taken for hysterical raisins
700  *                tty_mutex is taken to protect tty
701  *                ->siglock is taken to protect ->signal/->sighand
702  *                tasklist_lock is taken to walk process list for sessions
703  *                  ->siglock is taken to protect ->signal/->sighand
704  */
705
706 void disassociate_ctty(int on_exit)
707 {
708         struct tty_struct *tty;
709         struct pid *tty_pgrp = NULL;
710
711         if (!current->signal->leader)
712                 return;
713
714         tty = get_current_tty();
715         if (tty) {
716                 tty_pgrp = get_pid(tty->pgrp);
717                 lock_kernel();
718                 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
719                         tty_vhangup(tty);
720                 unlock_kernel();
721                 tty_kref_put(tty);
722         } else if (on_exit) {
723                 struct pid *old_pgrp;
724                 spin_lock_irq(&current->sighand->siglock);
725                 old_pgrp = current->signal->tty_old_pgrp;
726                 current->signal->tty_old_pgrp = NULL;
727                 spin_unlock_irq(&current->sighand->siglock);
728                 if (old_pgrp) {
729                         kill_pgrp(old_pgrp, SIGHUP, on_exit);
730                         kill_pgrp(old_pgrp, SIGCONT, on_exit);
731                         put_pid(old_pgrp);
732                 }
733                 return;
734         }
735         if (tty_pgrp) {
736                 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
737                 if (!on_exit)
738                         kill_pgrp(tty_pgrp, SIGCONT, on_exit);
739                 put_pid(tty_pgrp);
740         }
741
742         spin_lock_irq(&current->sighand->siglock);
743         put_pid(current->signal->tty_old_pgrp);
744         current->signal->tty_old_pgrp = NULL;
745         spin_unlock_irq(&current->sighand->siglock);
746
747         tty = get_current_tty();
748         if (tty) {
749                 unsigned long flags;
750                 spin_lock_irqsave(&tty->ctrl_lock, flags);
751                 put_pid(tty->session);
752                 put_pid(tty->pgrp);
753                 tty->session = NULL;
754                 tty->pgrp = NULL;
755                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
756                 tty_kref_put(tty);
757         } else {
758 #ifdef TTY_DEBUG_HANGUP
759                 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
760                        " = NULL", tty);
761 #endif
762         }
763
764         /* Now clear signal->tty under the lock */
765         read_lock(&tasklist_lock);
766         session_clear_tty(task_session(current));
767         read_unlock(&tasklist_lock);
768 }
769
770 /**
771  *
772  *      no_tty  - Ensure the current process does not have a controlling tty
773  */
774 void no_tty(void)
775 {
776         struct task_struct *tsk = current;
777         lock_kernel();
778         disassociate_ctty(0);
779         unlock_kernel();
780         proc_clear_tty(tsk);
781 }
782
783
784 /**
785  *      stop_tty        -       propagate flow control
786  *      @tty: tty to stop
787  *
788  *      Perform flow control to the driver. For PTY/TTY pairs we
789  *      must also propagate the TIOCKPKT status. May be called
790  *      on an already stopped device and will not re-call the driver
791  *      method.
792  *
793  *      This functionality is used by both the line disciplines for
794  *      halting incoming flow and by the driver. It may therefore be
795  *      called from any context, may be under the tty atomic_write_lock
796  *      but not always.
797  *
798  *      Locking:
799  *              Uses the tty control lock internally
800  */
801
802 void stop_tty(struct tty_struct *tty)
803 {
804         unsigned long flags;
805         spin_lock_irqsave(&tty->ctrl_lock, flags);
806         if (tty->stopped) {
807                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
808                 return;
809         }
810         tty->stopped = 1;
811         if (tty->link && tty->link->packet) {
812                 tty->ctrl_status &= ~TIOCPKT_START;
813                 tty->ctrl_status |= TIOCPKT_STOP;
814                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
815         }
816         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
817         if (tty->ops->stop)
818                 (tty->ops->stop)(tty);
819 }
820
821 EXPORT_SYMBOL(stop_tty);
822
823 /**
824  *      start_tty       -       propagate flow control
825  *      @tty: tty to start
826  *
827  *      Start a tty that has been stopped if at all possible. Perform
828  *      any necessary wakeups and propagate the TIOCPKT status. If this
829  *      is the tty was previous stopped and is being started then the
830  *      driver start method is invoked and the line discipline woken.
831  *
832  *      Locking:
833  *              ctrl_lock
834  */
835
836 void start_tty(struct tty_struct *tty)
837 {
838         unsigned long flags;
839         spin_lock_irqsave(&tty->ctrl_lock, flags);
840         if (!tty->stopped || tty->flow_stopped) {
841                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
842                 return;
843         }
844         tty->stopped = 0;
845         if (tty->link && tty->link->packet) {
846                 tty->ctrl_status &= ~TIOCPKT_STOP;
847                 tty->ctrl_status |= TIOCPKT_START;
848                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
849         }
850         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
851         if (tty->ops->start)
852                 (tty->ops->start)(tty);
853         /* If we have a running line discipline it may need kicking */
854         tty_wakeup(tty);
855 }
856
857 EXPORT_SYMBOL(start_tty);
858
859 /**
860  *      tty_read        -       read method for tty device files
861  *      @file: pointer to tty file
862  *      @buf: user buffer
863  *      @count: size of user buffer
864  *      @ppos: unused
865  *
866  *      Perform the read system call function on this terminal device. Checks
867  *      for hung up devices before calling the line discipline method.
868  *
869  *      Locking:
870  *              Locks the line discipline internally while needed. Multiple
871  *      read calls may be outstanding in parallel.
872  */
873
874 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
875                         loff_t *ppos)
876 {
877         int i;
878         struct tty_struct *tty;
879         struct inode *inode;
880         struct tty_ldisc *ld;
881
882         tty = (struct tty_struct *)file->private_data;
883         inode = file->f_path.dentry->d_inode;
884         if (tty_paranoia_check(tty, inode, "tty_read"))
885                 return -EIO;
886         if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
887                 return -EIO;
888
889         /* We want to wait for the line discipline to sort out in this
890            situation */
891         ld = tty_ldisc_ref_wait(tty);
892         if (ld->ops->read)
893                 i = (ld->ops->read)(tty, file, buf, count);
894         else
895                 i = -EIO;
896         tty_ldisc_deref(ld);
897         if (i > 0)
898                 inode->i_atime = current_fs_time(inode->i_sb);
899         return i;
900 }
901
902 void tty_write_unlock(struct tty_struct *tty)
903 {
904         mutex_unlock(&tty->atomic_write_lock);
905         wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
906 }
907
908 int tty_write_lock(struct tty_struct *tty, int ndelay)
909 {
910         if (!mutex_trylock(&tty->atomic_write_lock)) {
911                 if (ndelay)
912                         return -EAGAIN;
913                 if (mutex_lock_interruptible(&tty->atomic_write_lock))
914                         return -ERESTARTSYS;
915         }
916         return 0;
917 }
918
919 /*
920  * Split writes up in sane blocksizes to avoid
921  * denial-of-service type attacks
922  */
923 static inline ssize_t do_tty_write(
924         ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
925         struct tty_struct *tty,
926         struct file *file,
927         const char __user *buf,
928         size_t count)
929 {
930         ssize_t ret, written = 0;
931         unsigned int chunk;
932
933         ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
934         if (ret < 0)
935                 return ret;
936
937         /*
938          * We chunk up writes into a temporary buffer. This
939          * simplifies low-level drivers immensely, since they
940          * don't have locking issues and user mode accesses.
941          *
942          * But if TTY_NO_WRITE_SPLIT is set, we should use a
943          * big chunk-size..
944          *
945          * The default chunk-size is 2kB, because the NTTY
946          * layer has problems with bigger chunks. It will
947          * claim to be able to handle more characters than
948          * it actually does.
949          *
950          * FIXME: This can probably go away now except that 64K chunks
951          * are too likely to fail unless switched to vmalloc...
952          */
953         chunk = 2048;
954         if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
955                 chunk = 65536;
956         if (count < chunk)
957                 chunk = count;
958
959         /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
960         if (tty->write_cnt < chunk) {
961                 unsigned char *buf_chunk;
962
963                 if (chunk < 1024)
964                         chunk = 1024;
965
966                 buf_chunk = kmalloc(chunk, GFP_KERNEL);
967                 if (!buf_chunk) {
968                         ret = -ENOMEM;
969                         goto out;
970                 }
971                 kfree(tty->write_buf);
972                 tty->write_cnt = chunk;
973                 tty->write_buf = buf_chunk;
974         }
975
976         /* Do the write .. */
977         for (;;) {
978                 size_t size = count;
979                 if (size > chunk)
980                         size = chunk;
981                 ret = -EFAULT;
982                 if (copy_from_user(tty->write_buf, buf, size))
983                         break;
984                 ret = write(tty, file, tty->write_buf, size);
985                 if (ret <= 0)
986                         break;
987                 written += ret;
988                 buf += ret;
989                 count -= ret;
990                 if (!count)
991                         break;
992                 ret = -ERESTARTSYS;
993                 if (signal_pending(current))
994                         break;
995                 cond_resched();
996         }
997         if (written) {
998                 struct inode *inode = file->f_path.dentry->d_inode;
999                 inode->i_mtime = current_fs_time(inode->i_sb);
1000                 ret = written;
1001         }
1002 out:
1003         tty_write_unlock(tty);
1004         return ret;
1005 }
1006
1007 /**
1008  * tty_write_message - write a message to a certain tty, not just the console.
1009  * @tty: the destination tty_struct
1010  * @msg: the message to write
1011  *
1012  * This is used for messages that need to be redirected to a specific tty.
1013  * We don't put it into the syslog queue right now maybe in the future if
1014  * really needed.
1015  *
1016  * We must still hold the BKL and test the CLOSING flag for the moment.
1017  */
1018
1019 void tty_write_message(struct tty_struct *tty, char *msg)
1020 {
1021         if (tty) {
1022                 mutex_lock(&tty->atomic_write_lock);
1023                 lock_kernel();
1024                 if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
1025                         unlock_kernel();
1026                         tty->ops->write(tty, msg, strlen(msg));
1027                 } else
1028                         unlock_kernel();
1029                 tty_write_unlock(tty);
1030         }
1031         return;
1032 }
1033
1034
1035 /**
1036  *      tty_write               -       write method for tty device file
1037  *      @file: tty file pointer
1038  *      @buf: user data to write
1039  *      @count: bytes to write
1040  *      @ppos: unused
1041  *
1042  *      Write data to a tty device via the line discipline.
1043  *
1044  *      Locking:
1045  *              Locks the line discipline as required
1046  *              Writes to the tty driver are serialized by the atomic_write_lock
1047  *      and are then processed in chunks to the device. The line discipline
1048  *      write method will not be invoked in parallel for each device.
1049  */
1050
1051 static ssize_t tty_write(struct file *file, const char __user *buf,
1052                                                 size_t count, loff_t *ppos)
1053 {
1054         struct tty_struct *tty;
1055         struct inode *inode = file->f_path.dentry->d_inode;
1056         ssize_t ret;
1057         struct tty_ldisc *ld;
1058
1059         tty = (struct tty_struct *)file->private_data;
1060         if (tty_paranoia_check(tty, inode, "tty_write"))
1061                 return -EIO;
1062         if (!tty || !tty->ops->write ||
1063                 (test_bit(TTY_IO_ERROR, &tty->flags)))
1064                         return -EIO;
1065         /* Short term debug to catch buggy drivers */
1066         if (tty->ops->write_room == NULL)
1067                 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1068                         tty->driver->name);
1069         ld = tty_ldisc_ref_wait(tty);
1070         if (!ld->ops->write)
1071                 ret = -EIO;
1072         else
1073                 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1074         tty_ldisc_deref(ld);
1075         return ret;
1076 }
1077
1078 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1079                                                 size_t count, loff_t *ppos)
1080 {
1081         struct file *p = NULL;
1082
1083         spin_lock(&redirect_lock);
1084         if (redirect) {
1085                 get_file(redirect);
1086                 p = redirect;
1087         }
1088         spin_unlock(&redirect_lock);
1089
1090         if (p) {
1091                 ssize_t res;
1092                 res = vfs_write(p, buf, count, &p->f_pos);
1093                 fput(p);
1094                 return res;
1095         }
1096         return tty_write(file, buf, count, ppos);
1097 }
1098
1099 static char ptychar[] = "pqrstuvwxyzabcde";
1100
1101 /**
1102  *      pty_line_name   -       generate name for a pty
1103  *      @driver: the tty driver in use
1104  *      @index: the minor number
1105  *      @p: output buffer of at least 6 bytes
1106  *
1107  *      Generate a name from a driver reference and write it to the output
1108  *      buffer.
1109  *
1110  *      Locking: None
1111  */
1112 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1113 {
1114         int i = index + driver->name_base;
1115         /* ->name is initialized to "ttyp", but "tty" is expected */
1116         sprintf(p, "%s%c%x",
1117                 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1118                 ptychar[i >> 4 & 0xf], i & 0xf);
1119 }
1120
1121 /**
1122  *      tty_line_name   -       generate name for a tty
1123  *      @driver: the tty driver in use
1124  *      @index: the minor number
1125  *      @p: output buffer of at least 7 bytes
1126  *
1127  *      Generate a name from a driver reference and write it to the output
1128  *      buffer.
1129  *
1130  *      Locking: None
1131  */
1132 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1133 {
1134         sprintf(p, "%s%d", driver->name, index + driver->name_base);
1135 }
1136
1137 /**
1138  *      tty_driver_lookup_tty() - find an existing tty, if any
1139  *      @driver: the driver for the tty
1140  *      @idx:    the minor number
1141  *
1142  *      Return the tty, if found or ERR_PTR() otherwise.
1143  *
1144  *      Locking: tty_mutex must be held. If tty is found, the mutex must
1145  *      be held until the 'fast-open' is also done. Will change once we
1146  *      have refcounting in the driver and per driver locking
1147  */
1148 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1149                 struct inode *inode, int idx)
1150 {
1151         struct tty_struct *tty;
1152
1153         if (driver->ops->lookup)
1154                 return driver->ops->lookup(driver, inode, idx);
1155
1156         tty = driver->ttys[idx];
1157         return tty;
1158 }
1159
1160 /**
1161  *      tty_init_termios        -  helper for termios setup
1162  *      @tty: the tty to set up
1163  *
1164  *      Initialise the termios structures for this tty. Thus runs under
1165  *      the tty_mutex currently so we can be relaxed about ordering.
1166  */
1167
1168 int tty_init_termios(struct tty_struct *tty)
1169 {
1170         struct ktermios *tp;
1171         int idx = tty->index;
1172
1173         tp = tty->driver->termios[idx];
1174         if (tp == NULL) {
1175                 tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
1176                 if (tp == NULL)
1177                         return -ENOMEM;
1178                 memcpy(tp, &tty->driver->init_termios,
1179                                                 sizeof(struct ktermios));
1180                 tty->driver->termios[idx] = tp;
1181         }
1182         tty->termios = tp;
1183         tty->termios_locked = tp + 1;
1184
1185         /* Compatibility until drivers always set this */
1186         tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1187         tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1188         return 0;
1189 }
1190 EXPORT_SYMBOL_GPL(tty_init_termios);
1191
1192 /**
1193  *      tty_driver_install_tty() - install a tty entry in the driver
1194  *      @driver: the driver for the tty
1195  *      @tty: the tty
1196  *
1197  *      Install a tty object into the driver tables. The tty->index field
1198  *      will be set by the time this is called. This method is responsible
1199  *      for ensuring any need additional structures are allocated and
1200  *      configured.
1201  *
1202  *      Locking: tty_mutex for now
1203  */
1204 static int tty_driver_install_tty(struct tty_driver *driver,
1205                                                 struct tty_struct *tty)
1206 {
1207         int idx = tty->index;
1208         int ret;
1209
1210         if (driver->ops->install) {
1211                 lock_kernel();
1212                 ret = driver->ops->install(driver, tty);
1213                 unlock_kernel();
1214                 return ret;
1215         }
1216
1217         if (tty_init_termios(tty) == 0) {
1218                 lock_kernel();
1219                 tty_driver_kref_get(driver);
1220                 tty->count++;
1221                 driver->ttys[idx] = tty;
1222                 unlock_kernel();
1223                 return 0;
1224         }
1225         return -ENOMEM;
1226 }
1227
1228 /**
1229  *      tty_driver_remove_tty() - remove a tty from the driver tables
1230  *      @driver: the driver for the tty
1231  *      @idx:    the minor number
1232  *
1233  *      Remvoe a tty object from the driver tables. The tty->index field
1234  *      will be set by the time this is called.
1235  *
1236  *      Locking: tty_mutex for now
1237  */
1238 static void tty_driver_remove_tty(struct tty_driver *driver,
1239                                                 struct tty_struct *tty)
1240 {
1241         if (driver->ops->remove)
1242                 driver->ops->remove(driver, tty);
1243         else
1244                 driver->ttys[tty->index] = NULL;
1245 }
1246
1247 /*
1248  *      tty_reopen()    - fast re-open of an open tty
1249  *      @tty    - the tty to open
1250  *
1251  *      Return 0 on success, -errno on error.
1252  *
1253  *      Locking: tty_mutex must be held from the time the tty was found
1254  *               till this open completes.
1255  */
1256 static int tty_reopen(struct tty_struct *tty)
1257 {
1258         struct tty_driver *driver = tty->driver;
1259
1260         if (test_bit(TTY_CLOSING, &tty->flags))
1261                 return -EIO;
1262
1263         if (driver->type == TTY_DRIVER_TYPE_PTY &&
1264             driver->subtype == PTY_TYPE_MASTER) {
1265                 /*
1266                  * special case for PTY masters: only one open permitted,
1267                  * and the slave side open count is incremented as well.
1268                  */
1269                 if (tty->count)
1270                         return -EIO;
1271
1272                 tty->link->count++;
1273         }
1274         tty->count++;
1275         tty->driver = driver; /* N.B. why do this every time?? */
1276
1277         mutex_lock(&tty->ldisc_mutex);
1278         WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1279         mutex_unlock(&tty->ldisc_mutex);
1280
1281         return 0;
1282 }
1283
1284 /**
1285  *      tty_init_dev            -       initialise a tty device
1286  *      @driver: tty driver we are opening a device on
1287  *      @idx: device index
1288  *      @ret_tty: returned tty structure
1289  *      @first_ok: ok to open a new device (used by ptmx)
1290  *
1291  *      Prepare a tty device. This may not be a "new" clean device but
1292  *      could also be an active device. The pty drivers require special
1293  *      handling because of this.
1294  *
1295  *      Locking:
1296  *              The function is called under the tty_mutex, which
1297  *      protects us from the tty struct or driver itself going away.
1298  *
1299  *      On exit the tty device has the line discipline attached and
1300  *      a reference count of 1. If a pair was created for pty/tty use
1301  *      and the other was a pty master then it too has a reference count of 1.
1302  *
1303  * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1304  * failed open.  The new code protects the open with a mutex, so it's
1305  * really quite straightforward.  The mutex locking can probably be
1306  * relaxed for the (most common) case of reopening a tty.
1307  */
1308
1309 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
1310                                                                 int first_ok)
1311 {
1312         struct tty_struct *tty;
1313         int retval;
1314
1315         lock_kernel();
1316         /* Check if pty master is being opened multiple times */
1317         if (driver->subtype == PTY_TYPE_MASTER &&
1318                 (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
1319                 unlock_kernel();
1320                 return ERR_PTR(-EIO);
1321         }
1322         unlock_kernel();
1323
1324         /*
1325          * First time open is complex, especially for PTY devices.
1326          * This code guarantees that either everything succeeds and the
1327          * TTY is ready for operation, or else the table slots are vacated
1328          * and the allocated memory released.  (Except that the termios
1329          * and locked termios may be retained.)
1330          */
1331
1332         if (!try_module_get(driver->owner))
1333                 return ERR_PTR(-ENODEV);
1334
1335         tty = alloc_tty_struct();
1336         if (!tty)
1337                 goto fail_no_mem;
1338         initialize_tty_struct(tty, driver, idx);
1339
1340         retval = tty_driver_install_tty(driver, tty);
1341         if (retval < 0) {
1342                 free_tty_struct(tty);
1343                 module_put(driver->owner);
1344                 return ERR_PTR(retval);
1345         }
1346
1347         /*
1348          * Structures all installed ... call the ldisc open routines.
1349          * If we fail here just call release_tty to clean up.  No need
1350          * to decrement the use counts, as release_tty doesn't care.
1351          */
1352         retval = tty_ldisc_setup(tty, tty->link);
1353         if (retval)
1354                 goto release_mem_out;
1355         return tty;
1356
1357 fail_no_mem:
1358         module_put(driver->owner);
1359         return ERR_PTR(-ENOMEM);
1360
1361         /* call the tty release_tty routine to clean out this slot */
1362 release_mem_out:
1363         if (printk_ratelimit())
1364                 printk(KERN_INFO "tty_init_dev: ldisc open failed, "
1365                                  "clearing slot %d\n", idx);
1366         lock_kernel();
1367         release_tty(tty, idx);
1368         unlock_kernel();
1369         return ERR_PTR(retval);
1370 }
1371
1372 void tty_free_termios(struct tty_struct *tty)
1373 {
1374         struct ktermios *tp;
1375         int idx = tty->index;
1376         /* Kill this flag and push into drivers for locking etc */
1377         if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
1378                 /* FIXME: Locking on ->termios array */
1379                 tp = tty->termios;
1380                 tty->driver->termios[idx] = NULL;
1381                 kfree(tp);
1382         }
1383 }
1384 EXPORT_SYMBOL(tty_free_termios);
1385
1386 void tty_shutdown(struct tty_struct *tty)
1387 {
1388         tty_driver_remove_tty(tty->driver, tty);
1389         tty_free_termios(tty);
1390 }
1391 EXPORT_SYMBOL(tty_shutdown);
1392
1393 /**
1394  *      release_one_tty         -       release tty structure memory
1395  *      @kref: kref of tty we are obliterating
1396  *
1397  *      Releases memory associated with a tty structure, and clears out the
1398  *      driver table slots. This function is called when a device is no longer
1399  *      in use. It also gets called when setup of a device fails.
1400  *
1401  *      Locking:
1402  *              tty_mutex - sometimes only
1403  *              takes the file list lock internally when working on the list
1404  *      of ttys that the driver keeps.
1405  *
1406  *      This method gets called from a work queue so that the driver private
1407  *      cleanup ops can sleep (needed for USB at least)
1408  */
1409 static void release_one_tty(struct work_struct *work)
1410 {
1411         struct tty_struct *tty =
1412                 container_of(work, struct tty_struct, hangup_work);
1413         struct tty_driver *driver = tty->driver;
1414
1415         if (tty->ops->cleanup)
1416                 tty->ops->cleanup(tty);
1417
1418         tty->magic = 0;
1419         tty_driver_kref_put(driver);
1420         module_put(driver->owner);
1421
1422         file_list_lock();
1423         list_del_init(&tty->tty_files);
1424         file_list_unlock();
1425
1426         free_tty_struct(tty);
1427 }
1428
1429 static void queue_release_one_tty(struct kref *kref)
1430 {
1431         struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1432
1433         if (tty->ops->shutdown)
1434                 tty->ops->shutdown(tty);
1435         else
1436                 tty_shutdown(tty);
1437
1438         /* The hangup queue is now free so we can reuse it rather than
1439            waste a chunk of memory for each port */
1440         INIT_WORK(&tty->hangup_work, release_one_tty);
1441         schedule_work(&tty->hangup_work);
1442 }
1443
1444 /**
1445  *      tty_kref_put            -       release a tty kref
1446  *      @tty: tty device
1447  *
1448  *      Release a reference to a tty device and if need be let the kref
1449  *      layer destruct the object for us
1450  */
1451
1452 void tty_kref_put(struct tty_struct *tty)
1453 {
1454         if (tty)
1455                 kref_put(&tty->kref, queue_release_one_tty);
1456 }
1457 EXPORT_SYMBOL(tty_kref_put);
1458
1459 /**
1460  *      release_tty             -       release tty structure memory
1461  *
1462  *      Release both @tty and a possible linked partner (think pty pair),
1463  *      and decrement the refcount of the backing module.
1464  *
1465  *      Locking:
1466  *              tty_mutex - sometimes only
1467  *              takes the file list lock internally when working on the list
1468  *      of ttys that the driver keeps.
1469  *              FIXME: should we require tty_mutex is held here ??
1470  *
1471  */
1472 static void release_tty(struct tty_struct *tty, int idx)
1473 {
1474         /* This should always be true but check for the moment */
1475         WARN_ON(tty->index != idx);
1476
1477         if (tty->link)
1478                 tty_kref_put(tty->link);
1479         tty_kref_put(tty);
1480 }
1481
1482 /**
1483  *      tty_release             -       vfs callback for close
1484  *      @inode: inode of tty
1485  *      @filp: file pointer for handle to tty
1486  *
1487  *      Called the last time each file handle is closed that references
1488  *      this tty. There may however be several such references.
1489  *
1490  *      Locking:
1491  *              Takes bkl. See tty_release_dev
1492  *
1493  * Even releasing the tty structures is a tricky business.. We have
1494  * to be very careful that the structures are all released at the
1495  * same time, as interrupts might otherwise get the wrong pointers.
1496  *
1497  * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1498  * lead to double frees or releasing memory still in use.
1499  */
1500
1501 int tty_release(struct inode *inode, struct file *filp)
1502 {
1503         struct tty_struct *tty, *o_tty;
1504         int     pty_master, tty_closing, o_tty_closing, do_sleep;
1505         int     devpts;
1506         int     idx;
1507         char    buf[64];
1508
1509         tty = (struct tty_struct *)filp->private_data;
1510         if (tty_paranoia_check(tty, inode, "tty_release_dev"))
1511                 return 0;
1512
1513         lock_kernel();
1514         check_tty_count(tty, "tty_release_dev");
1515
1516         tty_fasync(-1, filp, 0);
1517
1518         idx = tty->index;
1519         pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1520                       tty->driver->subtype == PTY_TYPE_MASTER);
1521         devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1522         o_tty = tty->link;
1523
1524 #ifdef TTY_PARANOIA_CHECK
1525         if (idx < 0 || idx >= tty->driver->num) {
1526                 printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
1527                                   "free (%s)\n", tty->name);
1528                 unlock_kernel();
1529                 return 0;
1530         }
1531         if (!devpts) {
1532                 if (tty != tty->driver->ttys[idx]) {
1533                         unlock_kernel();
1534                         printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
1535                                "for (%s)\n", idx, tty->name);
1536                         return 0;
1537                 }
1538                 if (tty->termios != tty->driver->termios[idx]) {
1539                         unlock_kernel();
1540                         printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
1541                                "for (%s)\n",
1542                                idx, tty->name);
1543                         return 0;
1544                 }
1545         }
1546 #endif
1547
1548 #ifdef TTY_DEBUG_HANGUP
1549         printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
1550                tty_name(tty, buf), tty->count);
1551 #endif
1552
1553 #ifdef TTY_PARANOIA_CHECK
1554         if (tty->driver->other &&
1555              !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
1556                 if (o_tty != tty->driver->other->ttys[idx]) {
1557                         unlock_kernel();
1558                         printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
1559                                           "not o_tty for (%s)\n",
1560                                idx, tty->name);
1561                         return 0 ;
1562                 }
1563                 if (o_tty->termios != tty->driver->other->termios[idx]) {
1564                         unlock_kernel();
1565                         printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
1566                                           "not o_termios for (%s)\n",
1567                                idx, tty->name);
1568                         return 0;
1569                 }
1570                 if (o_tty->link != tty) {
1571                         unlock_kernel();
1572                         printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
1573                         return 0;
1574                 }
1575         }
1576 #endif
1577         if (tty->ops->close)
1578                 tty->ops->close(tty, filp);
1579
1580         unlock_kernel();
1581         /*
1582          * Sanity check: if tty->count is going to zero, there shouldn't be
1583          * any waiters on tty->read_wait or tty->write_wait.  We test the
1584          * wait queues and kick everyone out _before_ actually starting to
1585          * close.  This ensures that we won't block while releasing the tty
1586          * structure.
1587          *
1588          * The test for the o_tty closing is necessary, since the master and
1589          * slave sides may close in any order.  If the slave side closes out
1590          * first, its count will be one, since the master side holds an open.
1591          * Thus this test wouldn't be triggered at the time the slave closes,
1592          * so we do it now.
1593          *
1594          * Note that it's possible for the tty to be opened again while we're
1595          * flushing out waiters.  By recalculating the closing flags before
1596          * each iteration we avoid any problems.
1597          */
1598         while (1) {
1599                 /* Guard against races with tty->count changes elsewhere and
1600                    opens on /dev/tty */
1601
1602                 mutex_lock(&tty_mutex);
1603                 lock_kernel();
1604                 tty_closing = tty->count <= 1;
1605                 o_tty_closing = o_tty &&
1606                         (o_tty->count <= (pty_master ? 1 : 0));
1607                 do_sleep = 0;
1608
1609                 if (tty_closing) {
1610                         if (waitqueue_active(&tty->read_wait)) {
1611                                 wake_up_poll(&tty->read_wait, POLLIN);
1612                                 do_sleep++;
1613                         }
1614                         if (waitqueue_active(&tty->write_wait)) {
1615                                 wake_up_poll(&tty->write_wait, POLLOUT);
1616                                 do_sleep++;
1617                         }
1618                 }
1619                 if (o_tty_closing) {
1620                         if (waitqueue_active(&o_tty->read_wait)) {
1621                                 wake_up_poll(&o_tty->read_wait, POLLIN);
1622                                 do_sleep++;
1623                         }
1624                         if (waitqueue_active(&o_tty->write_wait)) {
1625                                 wake_up_poll(&o_tty->write_wait, POLLOUT);
1626                                 do_sleep++;
1627                         }
1628                 }
1629                 if (!do_sleep)
1630                         break;
1631
1632                 printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
1633                                     "active!\n", tty_name(tty, buf));
1634                 unlock_kernel();
1635                 mutex_unlock(&tty_mutex);
1636                 schedule();
1637         }
1638
1639         /*
1640          * The closing flags are now consistent with the open counts on
1641          * both sides, and we've completed the last operation that could
1642          * block, so it's safe to proceed with closing.
1643          */
1644         if (pty_master) {
1645                 if (--o_tty->count < 0) {
1646                         printk(KERN_WARNING "tty_release_dev: bad pty slave count "
1647                                             "(%d) for %s\n",
1648                                o_tty->count, tty_name(o_tty, buf));
1649                         o_tty->count = 0;
1650                 }
1651         }
1652         if (--tty->count < 0) {
1653                 printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
1654                        tty->count, tty_name(tty, buf));
1655                 tty->count = 0;
1656         }
1657
1658         /*
1659          * We've decremented tty->count, so we need to remove this file
1660          * descriptor off the tty->tty_files list; this serves two
1661          * purposes:
1662          *  - check_tty_count sees the correct number of file descriptors
1663          *    associated with this tty.
1664          *  - do_tty_hangup no longer sees this file descriptor as
1665          *    something that needs to be handled for hangups.
1666          */
1667         file_kill(filp);
1668         filp->private_data = NULL;
1669
1670         /*
1671          * Perform some housekeeping before deciding whether to return.
1672          *
1673          * Set the TTY_CLOSING flag if this was the last open.  In the
1674          * case of a pty we may have to wait around for the other side
1675          * to close, and TTY_CLOSING makes sure we can't be reopened.
1676          */
1677         if (tty_closing)
1678                 set_bit(TTY_CLOSING, &tty->flags);
1679         if (o_tty_closing)
1680                 set_bit(TTY_CLOSING, &o_tty->flags);
1681
1682         /*
1683          * If _either_ side is closing, make sure there aren't any
1684          * processes that still think tty or o_tty is their controlling
1685          * tty.
1686          */
1687         if (tty_closing || o_tty_closing) {
1688                 read_lock(&tasklist_lock);
1689                 session_clear_tty(tty->session);
1690                 if (o_tty)
1691                         session_clear_tty(o_tty->session);
1692                 read_unlock(&tasklist_lock);
1693         }
1694
1695         mutex_unlock(&tty_mutex);
1696
1697         /* check whether both sides are closing ... */
1698         if (!tty_closing || (o_tty && !o_tty_closing)) {
1699                 unlock_kernel();
1700                 return 0;
1701         }
1702
1703 #ifdef TTY_DEBUG_HANGUP
1704         printk(KERN_DEBUG "freeing tty structure...");
1705 #endif
1706         /*
1707          * Ask the line discipline code to release its structures
1708          */
1709         tty_ldisc_release(tty, o_tty);
1710         /*
1711          * The release_tty function takes care of the details of clearing
1712          * the slots and preserving the termios structure.
1713          */
1714         release_tty(tty, idx);
1715
1716         /* Make this pty number available for reallocation */
1717         if (devpts)
1718                 devpts_kill_index(inode, idx);
1719         unlock_kernel();
1720         return 0;
1721 }
1722
1723 /**
1724  *      tty_open                -       open a tty device
1725  *      @inode: inode of device file
1726  *      @filp: file pointer to tty
1727  *
1728  *      tty_open and tty_release keep up the tty count that contains the
1729  *      number of opens done on a tty. We cannot use the inode-count, as
1730  *      different inodes might point to the same tty.
1731  *
1732  *      Open-counting is needed for pty masters, as well as for keeping
1733  *      track of serial lines: DTR is dropped when the last close happens.
1734  *      (This is not done solely through tty->count, now.  - Ted 1/27/92)
1735  *
1736  *      The termios state of a pty is reset on first open so that
1737  *      settings don't persist across reuse.
1738  *
1739  *      Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
1740  *               tty->count should protect the rest.
1741  *               ->siglock protects ->signal/->sighand
1742  */
1743
1744 static int tty_open(struct inode *inode, struct file *filp)
1745 {
1746         struct tty_struct *tty = NULL;
1747         int noctty, retval;
1748         struct tty_driver *driver;
1749         int index;
1750         dev_t device = inode->i_rdev;
1751         unsigned saved_flags = filp->f_flags;
1752
1753         nonseekable_open(inode, filp);
1754
1755 retry_open:
1756         noctty = filp->f_flags & O_NOCTTY;
1757         index  = -1;
1758         retval = 0;
1759
1760         mutex_lock(&tty_mutex);
1761         lock_kernel();
1762
1763         if (device == MKDEV(TTYAUX_MAJOR, 0)) {
1764                 tty = get_current_tty();
1765                 if (!tty) {
1766                         unlock_kernel();
1767                         mutex_unlock(&tty_mutex);
1768                         return -ENXIO;
1769                 }
1770                 driver = tty_driver_kref_get(tty->driver);
1771                 index = tty->index;
1772                 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1773                 /* noctty = 1; */
1774                 /* FIXME: Should we take a driver reference ? */
1775                 tty_kref_put(tty);
1776                 goto got_driver;
1777         }
1778 #ifdef CONFIG_VT
1779         if (device == MKDEV(TTY_MAJOR, 0)) {
1780                 extern struct tty_driver *console_driver;
1781                 driver = tty_driver_kref_get(console_driver);
1782                 index = fg_console;
1783                 noctty = 1;
1784                 goto got_driver;
1785         }
1786 #endif
1787         if (device == MKDEV(TTYAUX_MAJOR, 1)) {
1788                 struct tty_driver *console_driver = console_device(&index);
1789                 if (console_driver) {
1790                         driver = tty_driver_kref_get(console_driver);
1791                         if (driver) {
1792                                 /* Don't let /dev/console block */
1793                                 filp->f_flags |= O_NONBLOCK;
1794                                 noctty = 1;
1795                                 goto got_driver;
1796                         }
1797                 }
1798                 unlock_kernel();
1799                 mutex_unlock(&tty_mutex);
1800                 return -ENODEV;
1801         }
1802
1803         driver = get_tty_driver(device, &index);
1804         if (!driver) {
1805                 unlock_kernel();
1806                 mutex_unlock(&tty_mutex);
1807                 return -ENODEV;
1808         }
1809 got_driver:
1810         if (!tty) {
1811                 /* check whether we're reopening an existing tty */
1812                 tty = tty_driver_lookup_tty(driver, inode, index);
1813
1814                 if (IS_ERR(tty)) {
1815                         unlock_kernel();
1816                         mutex_unlock(&tty_mutex);
1817                         return PTR_ERR(tty);
1818                 }
1819         }
1820
1821         if (tty) {
1822                 retval = tty_reopen(tty);
1823                 if (retval)
1824                         tty = ERR_PTR(retval);
1825         } else
1826                 tty = tty_init_dev(driver, index, 0);
1827
1828         mutex_unlock(&tty_mutex);
1829         tty_driver_kref_put(driver);
1830         if (IS_ERR(tty)) {
1831                 unlock_kernel();
1832                 return PTR_ERR(tty);
1833         }
1834
1835         filp->private_data = tty;
1836         file_move(filp, &tty->tty_files);
1837         check_tty_count(tty, "tty_open");
1838         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1839             tty->driver->subtype == PTY_TYPE_MASTER)
1840                 noctty = 1;
1841 #ifdef TTY_DEBUG_HANGUP
1842         printk(KERN_DEBUG "opening %s...", tty->name);
1843 #endif
1844         if (!retval) {
1845                 if (tty->ops->open)
1846                         retval = tty->ops->open(tty, filp);
1847                 else
1848                         retval = -ENODEV;
1849         }
1850         filp->f_flags = saved_flags;
1851
1852         if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
1853                                                 !capable(CAP_SYS_ADMIN))
1854                 retval = -EBUSY;
1855
1856         if (retval) {
1857 #ifdef TTY_DEBUG_HANGUP
1858                 printk(KERN_DEBUG "error %d in opening %s...", retval,
1859                        tty->name);
1860 #endif
1861                 tty_release(inode, filp);
1862                 if (retval != -ERESTARTSYS) {
1863                         unlock_kernel();
1864                         return retval;
1865                 }
1866                 if (signal_pending(current)) {
1867                         unlock_kernel();
1868                         return retval;
1869                 }
1870                 schedule();
1871                 /*
1872                  * Need to reset f_op in case a hangup happened.
1873                  */
1874                 if (filp->f_op == &hung_up_tty_fops)
1875                         filp->f_op = &tty_fops;
1876                 goto retry_open;
1877         }
1878         unlock_kernel();
1879
1880
1881         mutex_lock(&tty_mutex);
1882         lock_kernel();
1883         spin_lock_irq(&current->sighand->siglock);
1884         if (!noctty &&
1885             current->signal->leader &&
1886             !current->signal->tty &&
1887             tty->session == NULL)
1888                 __proc_set_tty(current, tty);
1889         spin_unlock_irq(&current->sighand->siglock);
1890         unlock_kernel();
1891         mutex_unlock(&tty_mutex);
1892         return 0;
1893 }
1894
1895
1896
1897 /**
1898  *      tty_poll        -       check tty status
1899  *      @filp: file being polled
1900  *      @wait: poll wait structures to update
1901  *
1902  *      Call the line discipline polling method to obtain the poll
1903  *      status of the device.
1904  *
1905  *      Locking: locks called line discipline but ldisc poll method
1906  *      may be re-entered freely by other callers.
1907  */
1908
1909 static unsigned int tty_poll(struct file *filp, poll_table *wait)
1910 {
1911         struct tty_struct *tty;
1912         struct tty_ldisc *ld;
1913         int ret = 0;
1914
1915         tty = (struct tty_struct *)filp->private_data;
1916         if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
1917                 return 0;
1918
1919         ld = tty_ldisc_ref_wait(tty);
1920         if (ld->ops->poll)
1921                 ret = (ld->ops->poll)(tty, filp, wait);
1922         tty_ldisc_deref(ld);
1923         return ret;
1924 }
1925
1926 static int tty_fasync(int fd, struct file *filp, int on)
1927 {
1928         struct tty_struct *tty;
1929         unsigned long flags;
1930         int retval = 0;
1931
1932         lock_kernel();
1933         tty = (struct tty_struct *)filp->private_data;
1934         if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
1935                 goto out;
1936
1937         retval = fasync_helper(fd, filp, on, &tty->fasync);
1938         if (retval <= 0)
1939                 goto out;
1940
1941         if (on) {
1942                 enum pid_type type;
1943                 struct pid *pid;
1944                 if (!waitqueue_active(&tty->read_wait))
1945                         tty->minimum_to_wake = 1;
1946                 spin_lock_irqsave(&tty->ctrl_lock, flags);
1947                 if (tty->pgrp) {
1948                         pid = tty->pgrp;
1949                         type = PIDTYPE_PGID;
1950                 } else {
1951                         pid = task_pid(current);
1952                         type = PIDTYPE_PID;
1953                 }
1954                 get_pid(pid);
1955                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1956                 retval = __f_setown(filp, pid, type, 0);
1957                 put_pid(pid);
1958                 if (retval)
1959                         goto out;
1960         } else {
1961                 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
1962                         tty->minimum_to_wake = N_TTY_BUF_SIZE;
1963         }
1964         retval = 0;
1965 out:
1966         unlock_kernel();
1967         return retval;
1968 }
1969
1970 /**
1971  *      tiocsti                 -       fake input character
1972  *      @tty: tty to fake input into
1973  *      @p: pointer to character
1974  *
1975  *      Fake input to a tty device. Does the necessary locking and
1976  *      input management.
1977  *
1978  *      FIXME: does not honour flow control ??
1979  *
1980  *      Locking:
1981  *              Called functions take tty_ldisc_lock
1982  *              current->signal->tty check is safe without locks
1983  *
1984  *      FIXME: may race normal receive processing
1985  */
1986
1987 static int tiocsti(struct tty_struct *tty, char __user *p)
1988 {
1989         char ch, mbz = 0;
1990         struct tty_ldisc *ld;
1991
1992         if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
1993                 return -EPERM;
1994         if (get_user(ch, p))
1995                 return -EFAULT;
1996         tty_audit_tiocsti(tty, ch);
1997         ld = tty_ldisc_ref_wait(tty);
1998         ld->ops->receive_buf(tty, &ch, &mbz, 1);
1999         tty_ldisc_deref(ld);
2000         return 0;
2001 }
2002
2003 /**
2004  *      tiocgwinsz              -       implement window query ioctl
2005  *      @tty; tty
2006  *      @arg: user buffer for result
2007  *
2008  *      Copies the kernel idea of the window size into the user buffer.
2009  *
2010  *      Locking: tty->termios_mutex is taken to ensure the winsize data
2011  *              is consistent.
2012  */
2013
2014 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2015 {
2016         int err;
2017
2018         mutex_lock(&tty->termios_mutex);
2019         err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2020         mutex_unlock(&tty->termios_mutex);
2021
2022         return err ? -EFAULT: 0;
2023 }
2024
2025 /**
2026  *      tty_do_resize           -       resize event
2027  *      @tty: tty being resized
2028  *      @rows: rows (character)
2029  *      @cols: cols (character)
2030  *
2031  *      Update the termios variables and send the necessary signals to
2032  *      peform a terminal resize correctly
2033  */
2034
2035 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2036 {
2037         struct pid *pgrp;
2038         unsigned long flags;
2039
2040         /* Lock the tty */
2041         mutex_lock(&tty->termios_mutex);
2042         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2043                 goto done;
2044         /* Get the PID values and reference them so we can
2045            avoid holding the tty ctrl lock while sending signals */
2046         spin_lock_irqsave(&tty->ctrl_lock, flags);
2047         pgrp = get_pid(tty->pgrp);
2048         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2049
2050         if (pgrp)
2051                 kill_pgrp(pgrp, SIGWINCH, 1);
2052         put_pid(pgrp);
2053
2054         tty->winsize = *ws;
2055 done:
2056         mutex_unlock(&tty->termios_mutex);
2057         return 0;
2058 }
2059
2060 /**
2061  *      tiocswinsz              -       implement window size set ioctl
2062  *      @tty; tty side of tty
2063  *      @arg: user buffer for result
2064  *
2065  *      Copies the user idea of the window size to the kernel. Traditionally
2066  *      this is just advisory information but for the Linux console it
2067  *      actually has driver level meaning and triggers a VC resize.
2068  *
2069  *      Locking:
2070  *              Driver dependant. The default do_resize method takes the
2071  *      tty termios mutex and ctrl_lock. The console takes its own lock
2072  *      then calls into the default method.
2073  */
2074
2075 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2076 {
2077         struct winsize tmp_ws;
2078         if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2079                 return -EFAULT;
2080
2081         if (tty->ops->resize)
2082                 return tty->ops->resize(tty, &tmp_ws);
2083         else
2084                 return tty_do_resize(tty, &tmp_ws);
2085 }
2086
2087 /**
2088  *      tioccons        -       allow admin to move logical console
2089  *      @file: the file to become console
2090  *
2091  *      Allow the adminstrator to move the redirected console device
2092  *
2093  *      Locking: uses redirect_lock to guard the redirect information
2094  */
2095
2096 static int tioccons(struct file *file)
2097 {
2098         if (!capable(CAP_SYS_ADMIN))
2099                 return -EPERM;
2100         if (file->f_op->write == redirected_tty_write) {
2101                 struct file *f;
2102                 spin_lock(&redirect_lock);
2103                 f = redirect;
2104                 redirect = NULL;
2105                 spin_unlock(&redirect_lock);
2106                 if (f)
2107                         fput(f);
2108                 return 0;
2109         }
2110         spin_lock(&redirect_lock);
2111         if (redirect) {
2112                 spin_unlock(&redirect_lock);
2113                 return -EBUSY;
2114         }
2115         get_file(file);
2116         redirect = file;
2117         spin_unlock(&redirect_lock);
2118         return 0;
2119 }
2120
2121 /**
2122  *      fionbio         -       non blocking ioctl
2123  *      @file: file to set blocking value
2124  *      @p: user parameter
2125  *
2126  *      Historical tty interfaces had a blocking control ioctl before
2127  *      the generic functionality existed. This piece of history is preserved
2128  *      in the expected tty API of posix OS's.
2129  *
2130  *      Locking: none, the open file handle ensures it won't go away.
2131  */
2132
2133 static int fionbio(struct file *file, int __user *p)
2134 {
2135         int nonblock;
2136
2137         if (get_user(nonblock, p))
2138                 return -EFAULT;
2139
2140         spin_lock(&file->f_lock);
2141         if (nonblock)
2142                 file->f_flags |= O_NONBLOCK;
2143         else
2144                 file->f_flags &= ~O_NONBLOCK;
2145         spin_unlock(&file->f_lock);
2146         return 0;
2147 }
2148
2149 /**
2150  *      tiocsctty       -       set controlling tty
2151  *      @tty: tty structure
2152  *      @arg: user argument
2153  *
2154  *      This ioctl is used to manage job control. It permits a session
2155  *      leader to set this tty as the controlling tty for the session.
2156  *
2157  *      Locking:
2158  *              Takes tty_mutex() to protect tty instance
2159  *              Takes tasklist_lock internally to walk sessions
2160  *              Takes ->siglock() when updating signal->tty
2161  */
2162
2163 static int tiocsctty(struct tty_struct *tty, int arg)
2164 {
2165         int ret = 0;
2166         if (current->signal->leader && (task_session(current) == tty->session))
2167                 return ret;
2168
2169         mutex_lock(&tty_mutex);
2170         /*
2171          * The process must be a session leader and
2172          * not have a controlling tty already.
2173          */
2174         if (!current->signal->leader || current->signal->tty) {
2175                 ret = -EPERM;
2176                 goto unlock;
2177         }
2178
2179         if (tty->session) {
2180                 /*
2181                  * This tty is already the controlling
2182                  * tty for another session group!
2183                  */
2184                 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2185                         /*
2186                          * Steal it away
2187                          */
2188                         read_lock(&tasklist_lock);
2189                         session_clear_tty(tty->session);
2190                         read_unlock(&tasklist_lock);
2191                 } else {
2192                         ret = -EPERM;
2193                         goto unlock;
2194                 }
2195         }
2196         proc_set_tty(current, tty);
2197 unlock:
2198         mutex_unlock(&tty_mutex);
2199         return ret;
2200 }
2201
2202 /**
2203  *      tty_get_pgrp    -       return a ref counted pgrp pid
2204  *      @tty: tty to read
2205  *
2206  *      Returns a refcounted instance of the pid struct for the process
2207  *      group controlling the tty.
2208  */
2209
2210 struct pid *tty_get_pgrp(struct tty_struct *tty)
2211 {
2212         unsigned long flags;
2213         struct pid *pgrp;
2214
2215         spin_lock_irqsave(&tty->ctrl_lock, flags);
2216         pgrp = get_pid(tty->pgrp);
2217         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2218
2219         return pgrp;
2220 }
2221 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2222
2223 /**
2224  *      tiocgpgrp               -       get process group
2225  *      @tty: tty passed by user
2226  *      @real_tty: tty side of the tty pased by the user if a pty else the tty
2227  *      @p: returned pid
2228  *
2229  *      Obtain the process group of the tty. If there is no process group
2230  *      return an error.
2231  *
2232  *      Locking: none. Reference to current->signal->tty is safe.
2233  */
2234
2235 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2236 {
2237         struct pid *pid;
2238         int ret;
2239         /*
2240          * (tty == real_tty) is a cheap way of
2241          * testing if the tty is NOT a master pty.
2242          */
2243         if (tty == real_tty && current->signal->tty != real_tty)
2244                 return -ENOTTY;
2245         pid = tty_get_pgrp(real_tty);
2246         ret =  put_user(pid_vnr(pid), p);
2247         put_pid(pid);
2248         return ret;
2249 }
2250
2251 /**
2252  *      tiocspgrp               -       attempt to set process group
2253  *      @tty: tty passed by user
2254  *      @real_tty: tty side device matching tty passed by user
2255  *      @p: pid pointer
2256  *
2257  *      Set the process group of the tty to the session passed. Only
2258  *      permitted where the tty session is our session.
2259  *
2260  *      Locking: RCU, ctrl lock
2261  */
2262
2263 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2264 {
2265         struct pid *pgrp;
2266         pid_t pgrp_nr;
2267         int retval = tty_check_change(real_tty);
2268         unsigned long flags;
2269
2270         if (retval == -EIO)
2271                 return -ENOTTY;
2272         if (retval)
2273                 return retval;
2274         if (!current->signal->tty ||
2275             (current->signal->tty != real_tty) ||
2276             (real_tty->session != task_session(current)))
2277                 return -ENOTTY;
2278         if (get_user(pgrp_nr, p))
2279                 return -EFAULT;
2280         if (pgrp_nr < 0)
2281                 return -EINVAL;
2282         rcu_read_lock();
2283         pgrp = find_vpid(pgrp_nr);
2284         retval = -ESRCH;
2285         if (!pgrp)
2286                 goto out_unlock;
2287         retval = -EPERM;
2288         if (session_of_pgrp(pgrp) != task_session(current))
2289                 goto out_unlock;
2290         retval = 0;
2291         spin_lock_irqsave(&tty->ctrl_lock, flags);
2292         put_pid(real_tty->pgrp);
2293         real_tty->pgrp = get_pid(pgrp);
2294         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2295 out_unlock:
2296         rcu_read_unlock();
2297         return retval;
2298 }
2299
2300 /**
2301  *      tiocgsid                -       get session id
2302  *      @tty: tty passed by user
2303  *      @real_tty: tty side of the tty pased by the user if a pty else the tty
2304  *      @p: pointer to returned session id
2305  *
2306  *      Obtain the session id of the tty. If there is no session
2307  *      return an error.
2308  *
2309  *      Locking: none. Reference to current->signal->tty is safe.
2310  */
2311
2312 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2313 {
2314         /*
2315          * (tty == real_tty) is a cheap way of
2316          * testing if the tty is NOT a master pty.
2317         */
2318         if (tty == real_tty && current->signal->tty != real_tty)
2319                 return -ENOTTY;
2320         if (!real_tty->session)
2321                 return -ENOTTY;
2322         return put_user(pid_vnr(real_tty->session), p);
2323 }
2324
2325 /**
2326  *      tiocsetd        -       set line discipline
2327  *      @tty: tty device
2328  *      @p: pointer to user data
2329  *
2330  *      Set the line discipline according to user request.
2331  *
2332  *      Locking: see tty_set_ldisc, this function is just a helper
2333  */
2334
2335 static int tiocsetd(struct tty_struct *tty, int __user *p)
2336 {
2337         int ldisc;
2338         int ret;
2339
2340         if (get_user(ldisc, p))
2341                 return -EFAULT;
2342
2343         ret = tty_set_ldisc(tty, ldisc);
2344
2345         return ret;
2346 }
2347
2348 /**
2349  *      send_break      -       performed time break
2350  *      @tty: device to break on
2351  *      @duration: timeout in mS
2352  *
2353  *      Perform a timed break on hardware that lacks its own driver level
2354  *      timed break functionality.
2355  *
2356  *      Locking:
2357  *              atomic_write_lock serializes
2358  *
2359  */
2360
2361 static int send_break(struct tty_struct *tty, unsigned int duration)
2362 {
2363         int retval;
2364
2365         if (tty->ops->break_ctl == NULL)
2366                 return 0;
2367
2368         if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2369                 retval = tty->ops->break_ctl(tty, duration);
2370         else {
2371                 /* Do the work ourselves */
2372                 if (tty_write_lock(tty, 0) < 0)
2373                         return -EINTR;
2374                 retval = tty->ops->break_ctl(tty, -1);
2375                 if (retval)
2376                         goto out;
2377                 if (!signal_pending(current))
2378                         msleep_interruptible(duration);
2379                 retval = tty->ops->break_ctl(tty, 0);
2380 out:
2381                 tty_write_unlock(tty);
2382                 if (signal_pending(current))
2383                         retval = -EINTR;
2384         }
2385         return retval;
2386 }
2387
2388 /**
2389  *      tty_tiocmget            -       get modem status
2390  *      @tty: tty device
2391  *      @file: user file pointer
2392  *      @p: pointer to result
2393  *
2394  *      Obtain the modem status bits from the tty driver if the feature
2395  *      is supported. Return -EINVAL if it is not available.
2396  *
2397  *      Locking: none (up to the driver)
2398  */
2399
2400 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
2401 {
2402         int retval = -EINVAL;
2403
2404         if (tty->ops->tiocmget) {
2405                 retval = tty->ops->tiocmget(tty, file);
2406
2407                 if (retval >= 0)
2408                         retval = put_user(retval, p);
2409         }
2410         return retval;
2411 }
2412
2413 /**
2414  *      tty_tiocmset            -       set modem status
2415  *      @tty: tty device
2416  *      @file: user file pointer
2417  *      @cmd: command - clear bits, set bits or set all
2418  *      @p: pointer to desired bits
2419  *
2420  *      Set the modem status bits from the tty driver if the feature
2421  *      is supported. Return -EINVAL if it is not available.
2422  *
2423  *      Locking: none (up to the driver)
2424  */
2425
2426 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
2427              unsigned __user *p)
2428 {
2429         int retval;
2430         unsigned int set, clear, val;
2431
2432         if (tty->ops->tiocmset == NULL)
2433                 return -EINVAL;
2434
2435         retval = get_user(val, p);
2436         if (retval)
2437                 return retval;
2438         set = clear = 0;
2439         switch (cmd) {
2440         case TIOCMBIS:
2441                 set = val;
2442                 break;
2443         case TIOCMBIC:
2444                 clear = val;
2445                 break;
2446         case TIOCMSET:
2447                 set = val;
2448                 clear = ~val;
2449                 break;
2450         }
2451         set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2452         clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2453         return tty->ops->tiocmset(tty, file, set, clear);
2454 }
2455
2456 struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2457 {
2458         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2459             tty->driver->subtype == PTY_TYPE_MASTER)
2460                 tty = tty->link;
2461         return tty;
2462 }
2463 EXPORT_SYMBOL(tty_pair_get_tty);
2464
2465 struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)
2466 {
2467         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2468             tty->driver->subtype == PTY_TYPE_MASTER)
2469             return tty;
2470         return tty->link;
2471 }
2472 EXPORT_SYMBOL(tty_pair_get_pty);
2473
2474 /*
2475  * Split this up, as gcc can choke on it otherwise..
2476  */
2477 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2478 {
2479         struct tty_struct *tty, *real_tty;
2480         void __user *p = (void __user *)arg;
2481         int retval;
2482         struct tty_ldisc *ld;
2483         struct inode *inode = file->f_dentry->d_inode;
2484
2485         tty = (struct tty_struct *)file->private_data;
2486         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2487                 return -EINVAL;
2488
2489         real_tty = tty_pair_get_tty(tty);
2490
2491         /*
2492          * Factor out some common prep work
2493          */
2494         switch (cmd) {
2495         case TIOCSETD:
2496         case TIOCSBRK:
2497         case TIOCCBRK:
2498         case TCSBRK:
2499         case TCSBRKP:
2500                 retval = tty_check_change(tty);
2501                 if (retval)
2502                         return retval;
2503                 if (cmd != TIOCCBRK) {
2504                         tty_wait_until_sent(tty, 0);
2505                         if (signal_pending(current))
2506                                 return -EINTR;
2507                 }
2508                 break;
2509         }
2510
2511         /*
2512          *      Now do the stuff.
2513          */
2514         switch (cmd) {
2515         case TIOCSTI:
2516                 return tiocsti(tty, p);
2517         case TIOCGWINSZ:
2518                 return tiocgwinsz(real_tty, p);
2519         case TIOCSWINSZ:
2520                 return tiocswinsz(real_tty, p);
2521         case TIOCCONS:
2522                 return real_tty != tty ? -EINVAL : tioccons(file);
2523         case FIONBIO:
2524                 return fionbio(file, p);
2525         case TIOCEXCL:
2526                 set_bit(TTY_EXCLUSIVE, &tty->flags);
2527                 return 0;
2528         case TIOCNXCL:
2529                 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2530                 return 0;
2531         case TIOCNOTTY:
2532                 if (current->signal->tty != tty)
2533                         return -ENOTTY;
2534                 no_tty();
2535                 return 0;
2536         case TIOCSCTTY:
2537                 return tiocsctty(tty, arg);
2538         case TIOCGPGRP:
2539                 return tiocgpgrp(tty, real_tty, p);
2540         case TIOCSPGRP:
2541                 return tiocspgrp(tty, real_tty, p);
2542         case TIOCGSID:
2543                 return tiocgsid(tty, real_tty, p);
2544         case TIOCGETD:
2545                 return put_user(tty->ldisc->ops->num, (int __user *)p);
2546         case TIOCSETD:
2547                 return tiocsetd(tty, p);
2548         /*
2549          * Break handling
2550          */
2551         case TIOCSBRK:  /* Turn break on, unconditionally */
2552                 if (tty->ops->break_ctl)
2553                         return tty->ops->break_ctl(tty, -1);
2554                 return 0;
2555         case TIOCCBRK:  /* Turn break off, unconditionally */
2556                 if (tty->ops->break_ctl)
2557                         return tty->ops->break_ctl(tty, 0);
2558                 return 0;
2559         case TCSBRK:   /* SVID version: non-zero arg --> no break */
2560                 /* non-zero arg means wait for all output data
2561                  * to be sent (performed above) but don't send break.
2562                  * This is used by the tcdrain() termios function.
2563                  */
2564                 if (!arg)
2565                         return send_break(tty, 250);
2566                 return 0;
2567         case TCSBRKP:   /* support for POSIX tcsendbreak() */
2568                 return send_break(tty, arg ? arg*100 : 250);
2569
2570         case TIOCMGET:
2571                 return tty_tiocmget(tty, file, p);
2572         case TIOCMSET:
2573         case TIOCMBIC:
2574         case TIOCMBIS:
2575                 return tty_tiocmset(tty, file, cmd, p);
2576         case TCFLSH:
2577                 switch (arg) {
2578                 case TCIFLUSH:
2579                 case TCIOFLUSH:
2580                 /* flush tty buffer and allow ldisc to process ioctl */
2581                         tty_buffer_flush(tty);
2582                         break;
2583                 }
2584                 break;
2585         }
2586         if (tty->ops->ioctl) {
2587                 retval = (tty->ops->ioctl)(tty, file, cmd, arg);
2588                 if (retval != -ENOIOCTLCMD)
2589                         return retval;
2590         }
2591         ld = tty_ldisc_ref_wait(tty);
2592         retval = -EINVAL;
2593         if (ld->ops->ioctl) {
2594                 retval = ld->ops->ioctl(tty, file, cmd, arg);
2595                 if (retval == -ENOIOCTLCMD)
2596                         retval = -EINVAL;
2597         }
2598         tty_ldisc_deref(ld);
2599         return retval;
2600 }
2601
2602 #ifdef CONFIG_COMPAT
2603 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2604                                 unsigned long arg)
2605 {
2606         struct inode *inode = file->f_dentry->d_inode;
2607         struct tty_struct *tty = file->private_data;
2608         struct tty_ldisc *ld;
2609         int retval = -ENOIOCTLCMD;
2610
2611         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2612                 return -EINVAL;
2613
2614         if (tty->ops->compat_ioctl) {
2615                 retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
2616                 if (retval != -ENOIOCTLCMD)
2617                         return retval;
2618         }
2619
2620         ld = tty_ldisc_ref_wait(tty);
2621         if (ld->ops->compat_ioctl)
2622                 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2623         tty_ldisc_deref(ld);
2624
2625         return retval;
2626 }
2627 #endif
2628
2629 /*
2630  * This implements the "Secure Attention Key" ---  the idea is to
2631  * prevent trojan horses by killing all processes associated with this
2632  * tty when the user hits the "Secure Attention Key".  Required for
2633  * super-paranoid applications --- see the Orange Book for more details.
2634  *
2635  * This code could be nicer; ideally it should send a HUP, wait a few
2636  * seconds, then send a INT, and then a KILL signal.  But you then
2637  * have to coordinate with the init process, since all processes associated
2638  * with the current tty must be dead before the new getty is allowed
2639  * to spawn.
2640  *
2641  * Now, if it would be correct ;-/ The current code has a nasty hole -
2642  * it doesn't catch files in flight. We may send the descriptor to ourselves
2643  * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2644  *
2645  * Nasty bug: do_SAK is being called in interrupt context.  This can
2646  * deadlock.  We punt it up to process context.  AKPM - 16Mar2001
2647  */
2648 void __do_SAK(struct tty_struct *tty)
2649 {
2650 #ifdef TTY_SOFT_SAK
2651         tty_hangup(tty);
2652 #else
2653         struct task_struct *g, *p;
2654         struct pid *session;
2655         int             i;
2656         struct file     *filp;
2657         struct fdtable *fdt;
2658
2659         if (!tty)
2660                 return;
2661         session = tty->session;
2662
2663         tty_ldisc_flush(tty);
2664
2665         tty_driver_flush_buffer(tty);
2666
2667         read_lock(&tasklist_lock);
2668         /* Kill the entire session */
2669         do_each_pid_task(session, PIDTYPE_SID, p) {
2670                 printk(KERN_NOTICE "SAK: killed process %d"
2671                         " (%s): task_session(p)==tty->session\n",
2672                         task_pid_nr(p), p->comm);
2673                 send_sig(SIGKILL, p, 1);
2674         } while_each_pid_task(session, PIDTYPE_SID, p);
2675         /* Now kill any processes that happen to have the
2676          * tty open.
2677          */
2678         do_each_thread(g, p) {
2679                 if (p->signal->tty == tty) {
2680                         printk(KERN_NOTICE "SAK: killed process %d"
2681                             " (%s): task_session(p)==tty->session\n",
2682                             task_pid_nr(p), p->comm);
2683                         send_sig(SIGKILL, p, 1);
2684                         continue;
2685                 }
2686                 task_lock(p);
2687                 if (p->files) {
2688                         /*
2689                          * We don't take a ref to the file, so we must
2690                          * hold ->file_lock instead.
2691                          */
2692                         spin_lock(&p->files->file_lock);
2693                         fdt = files_fdtable(p->files);
2694                         for (i = 0; i < fdt->max_fds; i++) {
2695                                 filp = fcheck_files(p->files, i);
2696                                 if (!filp)
2697                                         continue;
2698                                 if (filp->f_op->read == tty_read &&
2699                                     filp->private_data == tty) {
2700                                         printk(KERN_NOTICE "SAK: killed process %d"
2701                                             " (%s): fd#%d opened to the tty\n",
2702                                             task_pid_nr(p), p->comm, i);
2703                                         force_sig(SIGKILL, p);
2704                                         break;
2705                                 }
2706                         }
2707                         spin_unlock(&p->files->file_lock);
2708                 }
2709                 task_unlock(p);
2710         } while_each_thread(g, p);
2711         read_unlock(&tasklist_lock);
2712 #endif
2713 }
2714
2715 static void do_SAK_work(struct work_struct *work)
2716 {
2717         struct tty_struct *tty =
2718                 container_of(work, struct tty_struct, SAK_work);
2719         __do_SAK(tty);
2720 }
2721
2722 /*
2723  * The tq handling here is a little racy - tty->SAK_work may already be queued.
2724  * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2725  * the values which we write to it will be identical to the values which it
2726  * already has. --akpm
2727  */
2728 void do_SAK(struct tty_struct *tty)
2729 {
2730         if (!tty)
2731                 return;
2732         schedule_work(&tty->SAK_work);
2733 }
2734
2735 EXPORT_SYMBOL(do_SAK);
2736
2737 /**
2738  *      initialize_tty_struct
2739  *      @tty: tty to initialize
2740  *
2741  *      This subroutine initializes a tty structure that has been newly
2742  *      allocated.
2743  *
2744  *      Locking: none - tty in question must not be exposed at this point
2745  */
2746
2747 void initialize_tty_struct(struct tty_struct *tty,
2748                 struct tty_driver *driver, int idx)
2749 {
2750         memset(tty, 0, sizeof(struct tty_struct));
2751         kref_init(&tty->kref);
2752         tty->magic = TTY_MAGIC;
2753         tty_ldisc_init(tty);
2754         tty->session = NULL;
2755         tty->pgrp = NULL;
2756         tty->overrun_time = jiffies;
2757         tty->buf.head = tty->buf.tail = NULL;
2758         tty_buffer_init(tty);
2759         mutex_init(&tty->termios_mutex);
2760         mutex_init(&tty->ldisc_mutex);
2761         init_waitqueue_head(&tty->write_wait);
2762         init_waitqueue_head(&tty->read_wait);
2763         INIT_WORK(&tty->hangup_work, do_tty_hangup);
2764         mutex_init(&tty->atomic_read_lock);
2765         mutex_init(&tty->atomic_write_lock);
2766         mutex_init(&tty->output_lock);
2767         mutex_init(&tty->echo_lock);
2768         spin_lock_init(&tty->read_lock);
2769         spin_lock_init(&tty->ctrl_lock);
2770         INIT_LIST_HEAD(&tty->tty_files);
2771         INIT_WORK(&tty->SAK_work, do_SAK_work);
2772
2773         tty->driver = driver;
2774         tty->ops = driver->ops;
2775         tty->index = idx;
2776         tty_line_name(driver, idx, tty->name);
2777 }
2778
2779 /**
2780  *      tty_put_char    -       write one character to a tty
2781  *      @tty: tty
2782  *      @ch: character
2783  *
2784  *      Write one byte to the tty using the provided put_char method
2785  *      if present. Returns the number of characters successfully output.
2786  *
2787  *      Note: the specific put_char operation in the driver layer may go
2788  *      away soon. Don't call it directly, use this method
2789  */
2790
2791 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2792 {
2793         if (tty->ops->put_char)
2794                 return tty->ops->put_char(tty, ch);
2795         return tty->ops->write(tty, &ch, 1);
2796 }
2797 EXPORT_SYMBOL_GPL(tty_put_char);
2798
2799 struct class *tty_class;
2800
2801 /**
2802  *      tty_register_device - register a tty device
2803  *      @driver: the tty driver that describes the tty device
2804  *      @index: the index in the tty driver for this tty device
2805  *      @device: a struct device that is associated with this tty device.
2806  *              This field is optional, if there is no known struct device
2807  *              for this tty device it can be set to NULL safely.
2808  *
2809  *      Returns a pointer to the struct device for this tty device
2810  *      (or ERR_PTR(-EFOO) on error).
2811  *
2812  *      This call is required to be made to register an individual tty device
2813  *      if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set.  If
2814  *      that bit is not set, this function should not be called by a tty
2815  *      driver.
2816  *
2817  *      Locking: ??
2818  */
2819
2820 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2821                                    struct device *device)
2822 {
2823         char name[64];
2824         dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
2825
2826         if (index >= driver->num) {
2827                 printk(KERN_ERR "Attempt to register invalid tty line number "
2828                        " (%d).\n", index);
2829                 return ERR_PTR(-EINVAL);
2830         }
2831
2832         if (driver->type == TTY_DRIVER_TYPE_PTY)
2833                 pty_line_name(driver, index, name);
2834         else
2835                 tty_line_name(driver, index, name);
2836
2837         return device_create(tty_class, device, dev, NULL, name);
2838 }
2839 EXPORT_SYMBOL(tty_register_device);
2840
2841 /**
2842  *      tty_unregister_device - unregister a tty device
2843  *      @driver: the tty driver that describes the tty device
2844  *      @index: the index in the tty driver for this tty device
2845  *
2846  *      If a tty device is registered with a call to tty_register_device() then
2847  *      this function must be called when the tty device is gone.
2848  *
2849  *      Locking: ??
2850  */
2851
2852 void tty_unregister_device(struct tty_driver *driver, unsigned index)
2853 {
2854         device_destroy(tty_class,
2855                 MKDEV(driver->major, driver->minor_start) + index);
2856 }
2857 EXPORT_SYMBOL(tty_unregister_device);
2858
2859 struct tty_driver *alloc_tty_driver(int lines)
2860 {
2861         struct tty_driver *driver;
2862
2863         driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
2864         if (driver) {
2865                 kref_init(&driver->kref);
2866                 driver->magic = TTY_DRIVER_MAGIC;
2867                 driver->num = lines;
2868                 /* later we'll move allocation of tables here */
2869         }
2870         return driver;
2871 }
2872 EXPORT_SYMBOL(alloc_tty_driver);
2873
2874 static void destruct_tty_driver(struct kref *kref)
2875 {
2876         struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
2877         int i;
2878         struct ktermios *tp;
2879         void *p;
2880
2881         if (driver->flags & TTY_DRIVER_INSTALLED) {
2882                 /*
2883                  * Free the termios and termios_locked structures because
2884                  * we don't want to get memory leaks when modular tty
2885                  * drivers are removed from the kernel.
2886                  */
2887                 for (i = 0; i < driver->num; i++) {
2888                         tp = driver->termios[i];
2889                         if (tp) {
2890                                 driver->termios[i] = NULL;
2891                                 kfree(tp);
2892                         }
2893                         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
2894                                 tty_unregister_device(driver, i);
2895                 }
2896                 p = driver->ttys;
2897                 proc_tty_unregister_driver(driver);
2898                 driver->ttys = NULL;
2899                 driver->termios = NULL;
2900                 kfree(p);
2901                 cdev_del(&driver->cdev);
2902         }
2903         kfree(driver);
2904 }
2905
2906 void tty_driver_kref_put(struct tty_driver *driver)
2907 {
2908         kref_put(&driver->kref, destruct_tty_driver);
2909 }
2910 EXPORT_SYMBOL(tty_driver_kref_put);
2911
2912 void tty_set_operations(struct tty_driver *driver,
2913                         const struct tty_operations *op)
2914 {
2915         driver->ops = op;
2916 };
2917 EXPORT_SYMBOL(tty_set_operations);
2918
2919 void put_tty_driver(struct tty_driver *d)
2920 {
2921         tty_driver_kref_put(d);
2922 }
2923 EXPORT_SYMBOL(put_tty_driver);
2924
2925 /*
2926  * Called by a tty driver to register itself.
2927  */
2928 int tty_register_driver(struct tty_driver *driver)
2929 {
2930         int error;
2931         int i;
2932         dev_t dev;
2933         void **p = NULL;
2934
2935         if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
2936                 p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
2937                 if (!p)
2938                         return -ENOMEM;
2939         }
2940
2941         if (!driver->major) {
2942                 error = alloc_chrdev_region(&dev, driver->minor_start,
2943                                                 driver->num, driver->name);
2944                 if (!error) {
2945                         driver->major = MAJOR(dev);
2946                         driver->minor_start = MINOR(dev);
2947                 }
2948         } else {
2949                 dev = MKDEV(driver->major, driver->minor_start);
2950                 error = register_chrdev_region(dev, driver->num, driver->name);
2951         }
2952         if (error < 0) {
2953                 kfree(p);
2954                 return error;
2955         }
2956
2957         if (p) {
2958                 driver->ttys = (struct tty_struct **)p;
2959                 driver->termios = (struct ktermios **)(p + driver->num);
2960         } else {
2961                 driver->ttys = NULL;
2962                 driver->termios = NULL;
2963         }
2964
2965         cdev_init(&driver->cdev, &tty_fops);
2966         driver->cdev.owner = driver->owner;
2967         error = cdev_add(&driver->cdev, dev, driver->num);
2968         if (error) {
2969                 unregister_chrdev_region(dev, driver->num);
2970                 driver->ttys = NULL;
2971                 driver->termios = NULL;
2972                 kfree(p);
2973                 return error;
2974         }
2975
2976         mutex_lock(&tty_mutex);
2977         list_add(&driver->tty_drivers, &tty_drivers);
2978         mutex_unlock(&tty_mutex);
2979
2980         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
2981                 for (i = 0; i < driver->num; i++)
2982                     tty_register_device(driver, i, NULL);
2983         }
2984         proc_tty_register_driver(driver);
2985         driver->flags |= TTY_DRIVER_INSTALLED;
2986         return 0;
2987 }
2988
2989 EXPORT_SYMBOL(tty_register_driver);
2990
2991 /*
2992  * Called by a tty driver to unregister itself.
2993  */
2994 int tty_unregister_driver(struct tty_driver *driver)
2995 {
2996 #if 0
2997         /* FIXME */
2998         if (driver->refcount)
2999                 return -EBUSY;
3000 #endif
3001         unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3002                                 driver->num);
3003         mutex_lock(&tty_mutex);
3004         list_del(&driver->tty_drivers);
3005         mutex_unlock(&tty_mutex);
3006         return 0;
3007 }
3008
3009 EXPORT_SYMBOL(tty_unregister_driver);
3010
3011 dev_t tty_devnum(struct tty_struct *tty)
3012 {
3013         return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3014 }
3015 EXPORT_SYMBOL(tty_devnum);
3016
3017 void proc_clear_tty(struct task_struct *p)
3018 {
3019         unsigned long flags;
3020         struct tty_struct *tty;
3021         spin_lock_irqsave(&p->sighand->siglock, flags);
3022         tty = p->signal->tty;
3023         p->signal->tty = NULL;
3024         spin_unlock_irqrestore(&p->sighand->siglock, flags);
3025         tty_kref_put(tty);
3026 }
3027
3028 /* Called under the sighand lock */
3029
3030 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3031 {
3032         if (tty) {
3033                 unsigned long flags;
3034                 /* We should not have a session or pgrp to put here but.... */
3035                 spin_lock_irqsave(&tty->ctrl_lock, flags);
3036                 put_pid(tty->session);
3037                 put_pid(tty->pgrp);
3038                 tty->pgrp = get_pid(task_pgrp(tsk));
3039                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3040                 tty->session = get_pid(task_session(tsk));
3041                 if (tsk->signal->tty) {
3042                         printk(KERN_DEBUG "tty not NULL!!\n");
3043                         tty_kref_put(tsk->signal->tty);
3044                 }
3045         }
3046         put_pid(tsk->signal->tty_old_pgrp);
3047         tsk->signal->tty = tty_kref_get(tty);
3048         tsk->signal->tty_old_pgrp = NULL;
3049 }
3050
3051 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3052 {
3053         spin_lock_irq(&tsk->sighand->siglock);
3054         __proc_set_tty(tsk, tty);
3055         spin_unlock_irq(&tsk->sighand->siglock);
3056 }
3057
3058 struct tty_struct *get_current_tty(void)
3059 {
3060         struct tty_struct *tty;
3061         unsigned long flags;
3062
3063         spin_lock_irqsave(&current->sighand->siglock, flags);
3064         tty = tty_kref_get(current->signal->tty);
3065         spin_unlock_irqrestore(&current->sighand->siglock, flags);
3066         return tty;
3067 }
3068 EXPORT_SYMBOL_GPL(get_current_tty);
3069
3070 void tty_default_fops(struct file_operations *fops)
3071 {
3072         *fops = tty_fops;
3073 }
3074
3075 /*
3076  * Initialize the console device. This is called *early*, so
3077  * we can't necessarily depend on lots of kernel help here.
3078  * Just do some early initializations, and do the complex setup
3079  * later.
3080  */
3081 void __init console_init(void)
3082 {
3083         initcall_t *call;
3084
3085         /* Setup the default TTY line discipline. */
3086         tty_ldisc_begin();
3087
3088         /*
3089          * set up the console device so that later boot sequences can
3090          * inform about problems etc..
3091          */
3092         call = __con_initcall_start;
3093         while (call < __con_initcall_end) {
3094                 (*call)();
3095                 call++;
3096         }
3097 }
3098
3099 static char *tty_devnode(struct device *dev, mode_t *mode)
3100 {
3101         if (!mode)
3102                 return NULL;
3103         if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3104             dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3105                 *mode = 0666;
3106         return NULL;
3107 }
3108
3109 static int __init tty_class_init(void)
3110 {
3111         tty_class = class_create(THIS_MODULE, "tty");
3112         if (IS_ERR(tty_class))
3113                 return PTR_ERR(tty_class);
3114         tty_class->devnode = tty_devnode;
3115         return 0;
3116 }
3117
3118 postcore_initcall(tty_class_init);
3119
3120 /* 3/2004 jmc: why do these devices exist? */
3121
3122 static struct cdev tty_cdev, console_cdev;
3123
3124 /*
3125  * Ok, now we can initialize the rest of the tty devices and can count
3126  * on memory allocations, interrupts etc..
3127  */
3128 static int __init tty_init(void)
3129 {
3130         cdev_init(&tty_cdev, &tty_fops);
3131         if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3132             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3133                 panic("Couldn't register /dev/tty driver\n");
3134         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
3135                               "tty");
3136
3137         cdev_init(&console_cdev, &console_fops);
3138         if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3139             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3140                 panic("Couldn't register /dev/console driver\n");
3141         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3142                               "console");
3143
3144 #ifdef CONFIG_VT
3145         vty_init(&console_fops);
3146 #endif
3147         return 0;
3148 }
3149 module_init(tty_init);