Revert "ARM: tegra: tegratab: dummy change"
[linux-2.6.git] / drivers / tty / tty_io.c
1 /*
2  *  Copyright (C) 1991, 1992  Linus Torvalds
3  */
4
5 /*
6  * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
7  * or rs-channels. It also implements echoing, cooked mode etc.
8  *
9  * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
10  *
11  * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
12  * tty_struct and tty_queue structures.  Previously there was an array
13  * of 256 tty_struct's which was statically allocated, and the
14  * tty_queue structures were allocated at boot time.  Both are now
15  * dynamically allocated only when the tty is open.
16  *
17  * Also restructured routines so that there is more of a separation
18  * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
19  * the low-level tty routines (serial.c, pty.c, console.c).  This
20  * makes for cleaner and more compact code.  -TYT, 9/17/92
21  *
22  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
23  * which can be dynamically activated and de-activated by the line
24  * discipline handling modules (like SLIP).
25  *
26  * NOTE: pay no attention to the line discipline code (yet); its
27  * interface is still subject to change in this version...
28  * -- TYT, 1/31/92
29  *
30  * Added functionality to the OPOST tty handling.  No delays, but all
31  * other bits should be there.
32  *      -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
33  *
34  * Rewrote canonical mode and added more termios flags.
35  *      -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
36  *
37  * Reorganized FASYNC support so mouse code can share it.
38  *      -- ctm@ardi.com, 9Sep95
39  *
40  * New TIOCLINUX variants added.
41  *      -- mj@k332.feld.cvut.cz, 19-Nov-95
42  *
43  * Restrict vt switching via ioctl()
44  *      -- grif@cs.ucr.edu, 5-Dec-95
45  *
46  * Move console and virtual terminal code to more appropriate files,
47  * implement CONFIG_VT and generalize console device interface.
48  *      -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
49  *
50  * Rewrote tty_init_dev and tty_release_dev to eliminate races.
51  *      -- Bill Hawes <whawes@star.net>, June 97
52  *
53  * Added devfs support.
54  *      -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
55  *
56  * Added support for a Unix98-style ptmx device.
57  *      -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
58  *
59  * Reduced memory usage for older ARM systems
60  *      -- Russell King <rmk@arm.linux.org.uk>
61  *
62  * Move do_SAK() into process context.  Less stack use in devfs functions.
63  * alloc_tty_struct() always uses kmalloc()
64  *                       -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
65  */
66
67 #include <linux/types.h>
68 #include <linux/major.h>
69 #include <linux/errno.h>
70 #include <linux/signal.h>
71 #include <linux/fcntl.h>
72 #include <linux/sched.h>
73 #include <linux/interrupt.h>
74 #include <linux/tty.h>
75 #include <linux/tty_driver.h>
76 #include <linux/tty_flip.h>
77 #include <linux/devpts_fs.h>
78 #include <linux/file.h>
79 #include <linux/fdtable.h>
80 #include <linux/console.h>
81 #include <linux/timer.h>
82 #include <linux/ctype.h>
83 #include <linux/kd.h>
84 #include <linux/mm.h>
85 #include <linux/string.h>
86 #include <linux/slab.h>
87 #include <linux/poll.h>
88 #include <linux/proc_fs.h>
89 #include <linux/init.h>
90 #include <linux/module.h>
91 #include <linux/device.h>
92 #include <linux/wait.h>
93 #include <linux/bitops.h>
94 #include <linux/delay.h>
95 #include <linux/seq_file.h>
96 #include <linux/serial.h>
97 #include <linux/ratelimit.h>
98
99 #include <linux/uaccess.h>
100
101 #include <linux/kbd_kern.h>
102 #include <linux/vt_kern.h>
103 #include <linux/selection.h>
104
105 #include <linux/kmod.h>
106 #include <linux/nsproxy.h>
107
108 #undef TTY_DEBUG_HANGUP
109
110 #define TTY_PARANOIA_CHECK 1
111 #define CHECK_TTY_COUNT 1
112
113 struct ktermios tty_std_termios = {     /* for the benefit of tty drivers  */
114         .c_iflag = ICRNL | IXON,
115         .c_oflag = OPOST | ONLCR,
116         .c_cflag = B38400 | CS8 | CREAD | HUPCL,
117         .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
118                    ECHOCTL | ECHOKE | IEXTEN,
119         .c_cc = INIT_C_CC,
120         .c_ispeed = 38400,
121         .c_ospeed = 38400
122 };
123
124 EXPORT_SYMBOL(tty_std_termios);
125
126 /* This list gets poked at by procfs and various bits of boot up code. This
127    could do with some rationalisation such as pulling the tty proc function
128    into this file */
129
130 LIST_HEAD(tty_drivers);                 /* linked list of tty drivers */
131
132 /* Mutex to protect creating and releasing a tty. This is shared with
133    vt.c for deeply disgusting hack reasons */
134 DEFINE_MUTEX(tty_mutex);
135 EXPORT_SYMBOL(tty_mutex);
136
137 /* Spinlock to protect the tty->tty_files list */
138 DEFINE_SPINLOCK(tty_files_lock);
139
140 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
141 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
142 ssize_t redirected_tty_write(struct file *, const char __user *,
143                                                         size_t, loff_t *);
144 static unsigned int tty_poll(struct file *, poll_table *);
145 static int tty_open(struct inode *, struct file *);
146 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
147 #ifdef CONFIG_COMPAT
148 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
149                                 unsigned long arg);
150 #else
151 #define tty_compat_ioctl NULL
152 #endif
153 static int __tty_fasync(int fd, struct file *filp, int on);
154 static int tty_fasync(int fd, struct file *filp, int on);
155 static void release_tty(struct tty_struct *tty, int idx);
156 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
157 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
158
159 /**
160  *      alloc_tty_struct        -       allocate a tty object
161  *
162  *      Return a new empty tty structure. The data fields have not
163  *      been initialized in any way but has been zeroed
164  *
165  *      Locking: none
166  */
167
168 struct tty_struct *alloc_tty_struct(void)
169 {
170         return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
171 }
172
173 /**
174  *      free_tty_struct         -       free a disused tty
175  *      @tty: tty struct to free
176  *
177  *      Free the write buffers, tty queue and tty memory itself.
178  *
179  *      Locking: none. Must be called after tty is definitely unused
180  */
181
182 void free_tty_struct(struct tty_struct *tty)
183 {
184         if (tty->dev)
185                 put_device(tty->dev);
186         kfree(tty->write_buf);
187         tty_buffer_free_all(tty);
188         kfree(tty);
189 }
190
191 static inline struct tty_struct *file_tty(struct file *file)
192 {
193         return ((struct tty_file_private *)file->private_data)->tty;
194 }
195
196 int tty_alloc_file(struct file *file)
197 {
198         struct tty_file_private *priv;
199
200         priv = kmalloc(sizeof(*priv), GFP_KERNEL);
201         if (!priv)
202                 return -ENOMEM;
203
204         file->private_data = priv;
205
206         return 0;
207 }
208
209 /* Associate a new file with the tty structure */
210 void tty_add_file(struct tty_struct *tty, struct file *file)
211 {
212         struct tty_file_private *priv = file->private_data;
213
214         priv->tty = tty;
215         priv->file = file;
216
217         spin_lock(&tty_files_lock);
218         list_add(&priv->list, &tty->tty_files);
219         spin_unlock(&tty_files_lock);
220 }
221
222 /**
223  * tty_free_file - free file->private_data
224  *
225  * This shall be used only for fail path handling when tty_add_file was not
226  * called yet.
227  */
228 void tty_free_file(struct file *file)
229 {
230         struct tty_file_private *priv = file->private_data;
231
232         file->private_data = NULL;
233         kfree(priv);
234 }
235
236 /* Delete file from its tty */
237 void tty_del_file(struct file *file)
238 {
239         struct tty_file_private *priv = file->private_data;
240
241         spin_lock(&tty_files_lock);
242         list_del(&priv->list);
243         spin_unlock(&tty_files_lock);
244         tty_free_file(file);
245 }
246
247
248 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
249
250 /**
251  *      tty_name        -       return tty naming
252  *      @tty: tty structure
253  *      @buf: buffer for output
254  *
255  *      Convert a tty structure into a name. The name reflects the kernel
256  *      naming policy and if udev is in use may not reflect user space
257  *
258  *      Locking: none
259  */
260
261 char *tty_name(struct tty_struct *tty, char *buf)
262 {
263         if (!tty) /* Hmm.  NULL pointer.  That's fun. */
264                 strcpy(buf, "NULL tty");
265         else
266                 strcpy(buf, tty->name);
267         return buf;
268 }
269
270 EXPORT_SYMBOL(tty_name);
271
272 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
273                               const char *routine)
274 {
275 #ifdef TTY_PARANOIA_CHECK
276         if (!tty) {
277                 printk(KERN_WARNING
278                         "null TTY for (%d:%d) in %s\n",
279                         imajor(inode), iminor(inode), routine);
280                 return 1;
281         }
282         if (tty->magic != TTY_MAGIC) {
283                 printk(KERN_WARNING
284                         "bad magic number for tty struct (%d:%d) in %s\n",
285                         imajor(inode), iminor(inode), routine);
286                 return 1;
287         }
288 #endif
289         return 0;
290 }
291
292 static int check_tty_count(struct tty_struct *tty, const char *routine)
293 {
294 #ifdef CHECK_TTY_COUNT
295         struct list_head *p;
296         int count = 0;
297
298         spin_lock(&tty_files_lock);
299         list_for_each(p, &tty->tty_files) {
300                 count++;
301         }
302         spin_unlock(&tty_files_lock);
303         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
304             tty->driver->subtype == PTY_TYPE_SLAVE &&
305             tty->link && tty->link->count)
306                 count++;
307         if (tty->count != count) {
308                 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
309                                     "!= #fd's(%d) in %s\n",
310                        tty->name, tty->count, count, routine);
311                 return count;
312         }
313 #endif
314         return 0;
315 }
316
317 /**
318  *      get_tty_driver          -       find device of a tty
319  *      @dev_t: device identifier
320  *      @index: returns the index of the tty
321  *
322  *      This routine returns a tty driver structure, given a device number
323  *      and also passes back the index number.
324  *
325  *      Locking: caller must hold tty_mutex
326  */
327
328 static struct tty_driver *get_tty_driver(dev_t device, int *index)
329 {
330         struct tty_driver *p;
331
332         list_for_each_entry(p, &tty_drivers, tty_drivers) {
333                 dev_t base = MKDEV(p->major, p->minor_start);
334                 if (device < base || device >= base + p->num)
335                         continue;
336                 *index = device - base;
337                 return tty_driver_kref_get(p);
338         }
339         return NULL;
340 }
341
342 #ifdef CONFIG_CONSOLE_POLL
343
344 /**
345  *      tty_find_polling_driver -       find device of a polled tty
346  *      @name: name string to match
347  *      @line: pointer to resulting tty line nr
348  *
349  *      This routine returns a tty driver structure, given a name
350  *      and the condition that the tty driver is capable of polled
351  *      operation.
352  */
353 struct tty_driver *tty_find_polling_driver(char *name, int *line)
354 {
355         struct tty_driver *p, *res = NULL;
356         int tty_line = 0;
357         int len;
358         char *str, *stp;
359
360         for (str = name; *str; str++)
361                 if ((*str >= '0' && *str <= '9') || *str == ',')
362                         break;
363         if (!*str)
364                 return NULL;
365
366         len = str - name;
367         tty_line = simple_strtoul(str, &str, 10);
368
369         mutex_lock(&tty_mutex);
370         /* Search through the tty devices to look for a match */
371         list_for_each_entry(p, &tty_drivers, tty_drivers) {
372                 if (strncmp(name, p->name, len) != 0)
373                         continue;
374                 stp = str;
375                 if (*stp == ',')
376                         stp++;
377                 if (*stp == '\0')
378                         stp = NULL;
379
380                 if (tty_line >= 0 && tty_line < p->num && p->ops &&
381                     p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
382                         res = tty_driver_kref_get(p);
383                         *line = tty_line;
384                         break;
385                 }
386         }
387         mutex_unlock(&tty_mutex);
388
389         return res;
390 }
391 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
392 #endif
393
394 /**
395  *      tty_check_change        -       check for POSIX terminal changes
396  *      @tty: tty to check
397  *
398  *      If we try to write to, or set the state of, a terminal and we're
399  *      not in the foreground, send a SIGTTOU.  If the signal is blocked or
400  *      ignored, go ahead and perform the operation.  (POSIX 7.2)
401  *
402  *      Locking: ctrl_lock
403  */
404
405 int tty_check_change(struct tty_struct *tty)
406 {
407         unsigned long flags;
408         int ret = 0;
409
410         if (current->signal->tty != tty)
411                 return 0;
412
413         spin_lock_irqsave(&tty->ctrl_lock, flags);
414
415         if (!tty->pgrp) {
416                 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
417                 goto out_unlock;
418         }
419         if (task_pgrp(current) == tty->pgrp)
420                 goto out_unlock;
421         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
422         if (is_ignored(SIGTTOU))
423                 goto out;
424         if (is_current_pgrp_orphaned()) {
425                 ret = -EIO;
426                 goto out;
427         }
428         kill_pgrp(task_pgrp(current), SIGTTOU, 1);
429         set_thread_flag(TIF_SIGPENDING);
430         ret = -ERESTARTSYS;
431 out:
432         return ret;
433 out_unlock:
434         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
435         return ret;
436 }
437
438 EXPORT_SYMBOL(tty_check_change);
439
440 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
441                                 size_t count, loff_t *ppos)
442 {
443         return 0;
444 }
445
446 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
447                                  size_t count, loff_t *ppos)
448 {
449         return -EIO;
450 }
451
452 /* No kernel lock held - none needed ;) */
453 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
454 {
455         return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
456 }
457
458 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
459                 unsigned long arg)
460 {
461         return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
462 }
463
464 static long hung_up_tty_compat_ioctl(struct file *file,
465                                      unsigned int cmd, unsigned long arg)
466 {
467         return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
468 }
469
470 static const struct file_operations tty_fops = {
471         .llseek         = no_llseek,
472         .read           = tty_read,
473         .write          = tty_write,
474         .poll           = tty_poll,
475         .unlocked_ioctl = tty_ioctl,
476         .compat_ioctl   = tty_compat_ioctl,
477         .open           = tty_open,
478         .release        = tty_release,
479         .fasync         = tty_fasync,
480 };
481
482 static const struct file_operations console_fops = {
483         .llseek         = no_llseek,
484         .read           = tty_read,
485         .write          = redirected_tty_write,
486         .poll           = tty_poll,
487         .unlocked_ioctl = tty_ioctl,
488         .compat_ioctl   = tty_compat_ioctl,
489         .open           = tty_open,
490         .release        = tty_release,
491         .fasync         = tty_fasync,
492 };
493
494 static const struct file_operations hung_up_tty_fops = {
495         .llseek         = no_llseek,
496         .read           = hung_up_tty_read,
497         .write          = hung_up_tty_write,
498         .poll           = hung_up_tty_poll,
499         .unlocked_ioctl = hung_up_tty_ioctl,
500         .compat_ioctl   = hung_up_tty_compat_ioctl,
501         .release        = tty_release,
502 };
503
504 static DEFINE_SPINLOCK(redirect_lock);
505 static struct file *redirect;
506
507 /**
508  *      tty_wakeup      -       request more data
509  *      @tty: terminal
510  *
511  *      Internal and external helper for wakeups of tty. This function
512  *      informs the line discipline if present that the driver is ready
513  *      to receive more output data.
514  */
515
516 void tty_wakeup(struct tty_struct *tty)
517 {
518         struct tty_ldisc *ld;
519
520         if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
521                 ld = tty_ldisc_ref(tty);
522                 if (ld) {
523                         if (ld->ops->write_wakeup)
524                                 ld->ops->write_wakeup(tty);
525                         tty_ldisc_deref(ld);
526                 }
527         }
528         wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
529 }
530
531 EXPORT_SYMBOL_GPL(tty_wakeup);
532
533 /**
534  *      __tty_hangup            -       actual handler for hangup events
535  *      @work: tty device
536  *
537  *      This can be called by the "eventd" kernel thread.  That is process
538  *      synchronous but doesn't hold any locks, so we need to make sure we
539  *      have the appropriate locks for what we're doing.
540  *
541  *      The hangup event clears any pending redirections onto the hung up
542  *      device. It ensures future writes will error and it does the needed
543  *      line discipline hangup and signal delivery. The tty object itself
544  *      remains intact.
545  *
546  *      Locking:
547  *              BTM
548  *                redirect lock for undoing redirection
549  *                file list lock for manipulating list of ttys
550  *                tty_ldisc_lock from called functions
551  *                termios_mutex resetting termios data
552  *                tasklist_lock to walk task list for hangup event
553  *                  ->siglock to protect ->signal/->sighand
554  */
555 void __tty_hangup(struct tty_struct *tty)
556 {
557         struct file *cons_filp = NULL;
558         struct file *filp, *f = NULL;
559         struct task_struct *p;
560         struct tty_file_private *priv;
561         int    closecount = 0, n;
562         unsigned long flags;
563         int refs = 0;
564
565         if (!tty)
566                 return;
567
568
569         spin_lock(&redirect_lock);
570         if (redirect && file_tty(redirect) == tty) {
571                 f = redirect;
572                 redirect = NULL;
573         }
574         spin_unlock(&redirect_lock);
575
576         tty_lock();
577
578         /* some functions below drop BTM, so we need this bit */
579         set_bit(TTY_HUPPING, &tty->flags);
580
581         /* inuse_filps is protected by the single tty lock,
582            this really needs to change if we want to flush the
583            workqueue with the lock held */
584         check_tty_count(tty, "tty_hangup");
585
586         spin_lock(&tty_files_lock);
587         /* This breaks for file handles being sent over AF_UNIX sockets ? */
588         list_for_each_entry(priv, &tty->tty_files, list) {
589                 filp = priv->file;
590                 if (filp->f_op->write == redirected_tty_write)
591                         cons_filp = filp;
592                 if (filp->f_op->write != tty_write)
593                         continue;
594                 closecount++;
595                 __tty_fasync(-1, filp, 0);      /* can't block */
596                 filp->f_op = &hung_up_tty_fops;
597         }
598         spin_unlock(&tty_files_lock);
599
600         /*
601          * it drops BTM and thus races with reopen
602          * we protect the race by TTY_HUPPING
603          */
604         tty_ldisc_hangup(tty);
605
606         read_lock(&tasklist_lock);
607         if (tty->session) {
608                 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
609                         spin_lock_irq(&p->sighand->siglock);
610                         if (p->signal->tty == tty) {
611                                 p->signal->tty = NULL;
612                                 /* We defer the dereferences outside fo
613                                    the tasklist lock */
614                                 refs++;
615                         }
616                         if (!p->signal->leader) {
617                                 spin_unlock_irq(&p->sighand->siglock);
618                                 continue;
619                         }
620                         __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
621                         __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
622                         put_pid(p->signal->tty_old_pgrp);  /* A noop */
623                         spin_lock_irqsave(&tty->ctrl_lock, flags);
624                         if (tty->pgrp)
625                                 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
626                         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
627                         spin_unlock_irq(&p->sighand->siglock);
628                 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
629         }
630         read_unlock(&tasklist_lock);
631
632         spin_lock_irqsave(&tty->ctrl_lock, flags);
633         clear_bit(TTY_THROTTLED, &tty->flags);
634         clear_bit(TTY_PUSH, &tty->flags);
635         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
636         put_pid(tty->session);
637         put_pid(tty->pgrp);
638         tty->session = NULL;
639         tty->pgrp = NULL;
640         tty->ctrl_status = 0;
641         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
642
643         /* Account for the p->signal references we killed */
644         while (refs--)
645                 tty_kref_put(tty);
646
647         /*
648          * If one of the devices matches a console pointer, we
649          * cannot just call hangup() because that will cause
650          * tty->count and state->count to go out of sync.
651          * So we just call close() the right number of times.
652          */
653         if (cons_filp) {
654                 if (tty->ops->close)
655                         for (n = 0; n < closecount; n++)
656                                 tty->ops->close(tty, cons_filp);
657         } else if (tty->ops->hangup)
658                 (tty->ops->hangup)(tty);
659         /*
660          * We don't want to have driver/ldisc interactions beyond
661          * the ones we did here. The driver layer expects no
662          * calls after ->hangup() from the ldisc side. However we
663          * can't yet guarantee all that.
664          */
665         set_bit(TTY_HUPPED, &tty->flags);
666         clear_bit(TTY_HUPPING, &tty->flags);
667         tty_ldisc_enable(tty);
668
669         tty_unlock();
670
671         if (f)
672                 fput(f);
673 }
674
675 static void do_tty_hangup(struct work_struct *work)
676 {
677         struct tty_struct *tty =
678                 container_of(work, struct tty_struct, hangup_work);
679
680         __tty_hangup(tty);
681 }
682
683 /**
684  *      tty_hangup              -       trigger a hangup event
685  *      @tty: tty to hangup
686  *
687  *      A carrier loss (virtual or otherwise) has occurred on this like
688  *      schedule a hangup sequence to run after this event.
689  */
690
691 void tty_hangup(struct tty_struct *tty)
692 {
693 #ifdef TTY_DEBUG_HANGUP
694         char    buf[64];
695         printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
696 #endif
697         schedule_work(&tty->hangup_work);
698 }
699
700 EXPORT_SYMBOL(tty_hangup);
701
702 /**
703  *      tty_vhangup             -       process vhangup
704  *      @tty: tty to hangup
705  *
706  *      The user has asked via system call for the terminal to be hung up.
707  *      We do this synchronously so that when the syscall returns the process
708  *      is complete. That guarantee is necessary for security reasons.
709  */
710
711 void tty_vhangup(struct tty_struct *tty)
712 {
713 #ifdef TTY_DEBUG_HANGUP
714         char    buf[64];
715
716         printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
717 #endif
718         __tty_hangup(tty);
719 }
720
721 EXPORT_SYMBOL(tty_vhangup);
722
723
724 /**
725  *      tty_vhangup_self        -       process vhangup for own ctty
726  *
727  *      Perform a vhangup on the current controlling tty
728  */
729
730 void tty_vhangup_self(void)
731 {
732         struct tty_struct *tty;
733
734         tty = get_current_tty();
735         if (tty) {
736                 tty_vhangup(tty);
737                 tty_kref_put(tty);
738         }
739 }
740
741 /**
742  *      tty_hung_up_p           -       was tty hung up
743  *      @filp: file pointer of tty
744  *
745  *      Return true if the tty has been subject to a vhangup or a carrier
746  *      loss
747  */
748
749 int tty_hung_up_p(struct file *filp)
750 {
751         return (filp->f_op == &hung_up_tty_fops);
752 }
753
754 EXPORT_SYMBOL(tty_hung_up_p);
755
756 static void session_clear_tty(struct pid *session)
757 {
758         struct task_struct *p;
759         do_each_pid_task(session, PIDTYPE_SID, p) {
760                 proc_clear_tty(p);
761         } while_each_pid_task(session, PIDTYPE_SID, p);
762 }
763
764 /**
765  *      disassociate_ctty       -       disconnect controlling tty
766  *      @on_exit: true if exiting so need to "hang up" the session
767  *
768  *      This function is typically called only by the session leader, when
769  *      it wants to disassociate itself from its controlling tty.
770  *
771  *      It performs the following functions:
772  *      (1)  Sends a SIGHUP and SIGCONT to the foreground process group
773  *      (2)  Clears the tty from being controlling the session
774  *      (3)  Clears the controlling tty for all processes in the
775  *              session group.
776  *
777  *      The argument on_exit is set to 1 if called when a process is
778  *      exiting; it is 0 if called by the ioctl TIOCNOTTY.
779  *
780  *      Locking:
781  *              BTM is taken for hysterical raisins, and held when
782  *                called from no_tty().
783  *                tty_mutex is taken to protect tty
784  *                ->siglock is taken to protect ->signal/->sighand
785  *                tasklist_lock is taken to walk process list for sessions
786  *                  ->siglock is taken to protect ->signal/->sighand
787  */
788
789 void disassociate_ctty(int on_exit)
790 {
791         struct tty_struct *tty;
792
793         if (!current->signal->leader)
794                 return;
795
796         tty = get_current_tty();
797         if (tty) {
798                 struct pid *tty_pgrp = get_pid(tty->pgrp);
799                 if (on_exit) {
800                         if (tty->driver->type != TTY_DRIVER_TYPE_PTY)
801                                 tty_vhangup(tty);
802                 }
803                 tty_kref_put(tty);
804                 if (tty_pgrp) {
805                         kill_pgrp(tty_pgrp, SIGHUP, on_exit);
806                         if (!on_exit)
807                                 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
808                         put_pid(tty_pgrp);
809                 }
810         } else if (on_exit) {
811                 struct pid *old_pgrp;
812                 spin_lock_irq(&current->sighand->siglock);
813                 old_pgrp = current->signal->tty_old_pgrp;
814                 current->signal->tty_old_pgrp = NULL;
815                 spin_unlock_irq(&current->sighand->siglock);
816                 if (old_pgrp) {
817                         kill_pgrp(old_pgrp, SIGHUP, on_exit);
818                         kill_pgrp(old_pgrp, SIGCONT, on_exit);
819                         put_pid(old_pgrp);
820                 }
821                 return;
822         }
823
824         spin_lock_irq(&current->sighand->siglock);
825         put_pid(current->signal->tty_old_pgrp);
826         current->signal->tty_old_pgrp = NULL;
827         spin_unlock_irq(&current->sighand->siglock);
828
829         tty = get_current_tty();
830         if (tty) {
831                 unsigned long flags;
832                 spin_lock_irqsave(&tty->ctrl_lock, flags);
833                 put_pid(tty->session);
834                 put_pid(tty->pgrp);
835                 tty->session = NULL;
836                 tty->pgrp = NULL;
837                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
838                 tty_kref_put(tty);
839         } else {
840 #ifdef TTY_DEBUG_HANGUP
841                 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
842                        " = NULL", tty);
843 #endif
844         }
845
846         /* Now clear signal->tty under the lock */
847         read_lock(&tasklist_lock);
848         session_clear_tty(task_session(current));
849         read_unlock(&tasklist_lock);
850 }
851
852 /**
853  *
854  *      no_tty  - Ensure the current process does not have a controlling tty
855  */
856 void no_tty(void)
857 {
858         struct task_struct *tsk = current;
859         tty_lock();
860         disassociate_ctty(0);
861         tty_unlock();
862         proc_clear_tty(tsk);
863 }
864
865
866 /**
867  *      stop_tty        -       propagate flow control
868  *      @tty: tty to stop
869  *
870  *      Perform flow control to the driver. For PTY/TTY pairs we
871  *      must also propagate the TIOCKPKT status. May be called
872  *      on an already stopped device and will not re-call the driver
873  *      method.
874  *
875  *      This functionality is used by both the line disciplines for
876  *      halting incoming flow and by the driver. It may therefore be
877  *      called from any context, may be under the tty atomic_write_lock
878  *      but not always.
879  *
880  *      Locking:
881  *              Uses the tty control lock internally
882  */
883
884 void stop_tty(struct tty_struct *tty)
885 {
886         unsigned long flags;
887         spin_lock_irqsave(&tty->ctrl_lock, flags);
888         if (tty->stopped) {
889                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
890                 return;
891         }
892         tty->stopped = 1;
893         if (tty->link && tty->link->packet) {
894                 tty->ctrl_status &= ~TIOCPKT_START;
895                 tty->ctrl_status |= TIOCPKT_STOP;
896                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
897         }
898         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
899         if (tty->ops->stop)
900                 (tty->ops->stop)(tty);
901 }
902
903 EXPORT_SYMBOL(stop_tty);
904
905 /**
906  *      start_tty       -       propagate flow control
907  *      @tty: tty to start
908  *
909  *      Start a tty that has been stopped if at all possible. Perform
910  *      any necessary wakeups and propagate the TIOCPKT status. If this
911  *      is the tty was previous stopped and is being started then the
912  *      driver start method is invoked and the line discipline woken.
913  *
914  *      Locking:
915  *              ctrl_lock
916  */
917
918 void start_tty(struct tty_struct *tty)
919 {
920         unsigned long flags;
921         spin_lock_irqsave(&tty->ctrl_lock, flags);
922         if (!tty->stopped || tty->flow_stopped) {
923                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
924                 return;
925         }
926         tty->stopped = 0;
927         if (tty->link && tty->link->packet) {
928                 tty->ctrl_status &= ~TIOCPKT_STOP;
929                 tty->ctrl_status |= TIOCPKT_START;
930                 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
931         }
932         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
933         if (tty->ops->start)
934                 (tty->ops->start)(tty);
935         /* If we have a running line discipline it may need kicking */
936         tty_wakeup(tty);
937 }
938
939 EXPORT_SYMBOL(start_tty);
940
941 /* We limit tty time update visibility to every 8 seconds or so. */
942 static void tty_update_time(struct timespec *time)
943 {
944         unsigned long sec = get_seconds() & ~7;
945         if ((long)(sec - time->tv_sec) > 0)
946                 time->tv_sec = sec;
947 }
948
949 /**
950  *      tty_read        -       read method for tty device files
951  *      @file: pointer to tty file
952  *      @buf: user buffer
953  *      @count: size of user buffer
954  *      @ppos: unused
955  *
956  *      Perform the read system call function on this terminal device. Checks
957  *      for hung up devices before calling the line discipline method.
958  *
959  *      Locking:
960  *              Locks the line discipline internally while needed. Multiple
961  *      read calls may be outstanding in parallel.
962  */
963
964 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
965                         loff_t *ppos)
966 {
967         int i;
968         struct inode *inode = file->f_path.dentry->d_inode;
969         struct tty_struct *tty = file_tty(file);
970         struct tty_ldisc *ld;
971
972         if (tty_paranoia_check(tty, inode, "tty_read"))
973                 return -EIO;
974         if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
975                 return -EIO;
976
977         /* We want to wait for the line discipline to sort out in this
978            situation */
979         ld = tty_ldisc_ref_wait(tty);
980         if (ld->ops->read)
981                 i = (ld->ops->read)(tty, file, buf, count);
982         else
983                 i = -EIO;
984         tty_ldisc_deref(ld);
985
986         if (i > 0)
987                 tty_update_time(&inode->i_atime);
988
989         return i;
990 }
991
992 void tty_write_unlock(struct tty_struct *tty)
993         __releases(&tty->atomic_write_lock)
994 {
995         mutex_unlock(&tty->atomic_write_lock);
996         wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
997 }
998
999 int tty_write_lock(struct tty_struct *tty, int ndelay)
1000         __acquires(&tty->atomic_write_lock)
1001 {
1002         if (!mutex_trylock(&tty->atomic_write_lock)) {
1003                 if (ndelay)
1004                         return -EAGAIN;
1005                 if (mutex_lock_interruptible(&tty->atomic_write_lock))
1006                         return -ERESTARTSYS;
1007         }
1008         return 0;
1009 }
1010
1011 /*
1012  * Split writes up in sane blocksizes to avoid
1013  * denial-of-service type attacks
1014  */
1015 static inline ssize_t do_tty_write(
1016         ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1017         struct tty_struct *tty,
1018         struct file *file,
1019         const char __user *buf,
1020         size_t count)
1021 {
1022         ssize_t ret, written = 0;
1023         unsigned int chunk;
1024
1025         ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1026         if (ret < 0)
1027                 return ret;
1028
1029         /*
1030          * We chunk up writes into a temporary buffer. This
1031          * simplifies low-level drivers immensely, since they
1032          * don't have locking issues and user mode accesses.
1033          *
1034          * But if TTY_NO_WRITE_SPLIT is set, we should use a
1035          * big chunk-size..
1036          *
1037          * The default chunk-size is 2kB, because the NTTY
1038          * layer has problems with bigger chunks. It will
1039          * claim to be able to handle more characters than
1040          * it actually does.
1041          *
1042          * FIXME: This can probably go away now except that 64K chunks
1043          * are too likely to fail unless switched to vmalloc...
1044          */
1045         chunk = 2048;
1046         if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1047                 chunk = 65536;
1048         if (count < chunk)
1049                 chunk = count;
1050
1051         /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1052         if (tty->write_cnt < chunk) {
1053                 unsigned char *buf_chunk;
1054
1055                 if (chunk < 1024)
1056                         chunk = 1024;
1057
1058                 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1059                 if (!buf_chunk) {
1060                         ret = -ENOMEM;
1061                         goto out;
1062                 }
1063                 kfree(tty->write_buf);
1064                 tty->write_cnt = chunk;
1065                 tty->write_buf = buf_chunk;
1066         }
1067
1068         /* Do the write .. */
1069         for (;;) {
1070                 size_t size = count;
1071                 if (size > chunk)
1072                         size = chunk;
1073                 ret = -EFAULT;
1074                 if (copy_from_user(tty->write_buf, buf, size))
1075                         break;
1076                 ret = write(tty, file, tty->write_buf, size);
1077                 if (ret <= 0)
1078                         break;
1079                 written += ret;
1080                 buf += ret;
1081                 count -= ret;
1082                 if (!count)
1083                         break;
1084                 ret = -ERESTARTSYS;
1085                 if (signal_pending(current))
1086                         break;
1087                 cond_resched();
1088         }
1089         if (written) {
1090                 struct inode *inode = file->f_path.dentry->d_inode;
1091                 tty_update_time(&inode->i_mtime);
1092                 ret = written;
1093         }
1094 out:
1095         tty_write_unlock(tty);
1096         return ret;
1097 }
1098
1099 /**
1100  * tty_write_message - write a message to a certain tty, not just the console.
1101  * @tty: the destination tty_struct
1102  * @msg: the message to write
1103  *
1104  * This is used for messages that need to be redirected to a specific tty.
1105  * We don't put it into the syslog queue right now maybe in the future if
1106  * really needed.
1107  *
1108  * We must still hold the BTM and test the CLOSING flag for the moment.
1109  */
1110
1111 void tty_write_message(struct tty_struct *tty, char *msg)
1112 {
1113         if (tty) {
1114                 mutex_lock(&tty->atomic_write_lock);
1115                 tty_lock();
1116                 if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
1117                         tty_unlock();
1118                         tty->ops->write(tty, msg, strlen(msg));
1119                 } else
1120                         tty_unlock();
1121                 tty_write_unlock(tty);
1122         }
1123         return;
1124 }
1125
1126
1127 /**
1128  *      tty_write               -       write method for tty device file
1129  *      @file: tty file pointer
1130  *      @buf: user data to write
1131  *      @count: bytes to write
1132  *      @ppos: unused
1133  *
1134  *      Write data to a tty device via the line discipline.
1135  *
1136  *      Locking:
1137  *              Locks the line discipline as required
1138  *              Writes to the tty driver are serialized by the atomic_write_lock
1139  *      and are then processed in chunks to the device. The line discipline
1140  *      write method will not be invoked in parallel for each device.
1141  */
1142
1143 static ssize_t tty_write(struct file *file, const char __user *buf,
1144                                                 size_t count, loff_t *ppos)
1145 {
1146         struct inode *inode = file->f_path.dentry->d_inode;
1147         struct tty_struct *tty = file_tty(file);
1148         struct tty_ldisc *ld;
1149         ssize_t ret;
1150
1151         if (tty_paranoia_check(tty, inode, "tty_write"))
1152                 return -EIO;
1153         if (!tty || !tty->ops->write ||
1154                 (test_bit(TTY_IO_ERROR, &tty->flags)))
1155                         return -EIO;
1156         /* Short term debug to catch buggy drivers */
1157         if (tty->ops->write_room == NULL)
1158                 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1159                         tty->driver->name);
1160         ld = tty_ldisc_ref_wait(tty);
1161         if (!ld->ops->write)
1162                 ret = -EIO;
1163         else
1164                 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1165         tty_ldisc_deref(ld);
1166         return ret;
1167 }
1168
1169 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1170                                                 size_t count, loff_t *ppos)
1171 {
1172         struct file *p = NULL;
1173
1174         spin_lock(&redirect_lock);
1175         if (redirect) {
1176                 get_file(redirect);
1177                 p = redirect;
1178         }
1179         spin_unlock(&redirect_lock);
1180
1181         if (p) {
1182                 ssize_t res;
1183                 res = vfs_write(p, buf, count, &p->f_pos);
1184                 fput(p);
1185                 return res;
1186         }
1187         return tty_write(file, buf, count, ppos);
1188 }
1189
1190 static char ptychar[] = "pqrstuvwxyzabcde";
1191
1192 /**
1193  *      pty_line_name   -       generate name for a pty
1194  *      @driver: the tty driver in use
1195  *      @index: the minor number
1196  *      @p: output buffer of at least 6 bytes
1197  *
1198  *      Generate a name from a driver reference and write it to the output
1199  *      buffer.
1200  *
1201  *      Locking: None
1202  */
1203 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1204 {
1205         int i = index + driver->name_base;
1206         /* ->name is initialized to "ttyp", but "tty" is expected */
1207         sprintf(p, "%s%c%x",
1208                 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1209                 ptychar[i >> 4 & 0xf], i & 0xf);
1210 }
1211
1212 /**
1213  *      tty_line_name   -       generate name for a tty
1214  *      @driver: the tty driver in use
1215  *      @index: the minor number
1216  *      @p: output buffer of at least 7 bytes
1217  *
1218  *      Generate a name from a driver reference and write it to the output
1219  *      buffer.
1220  *
1221  *      Locking: None
1222  */
1223 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1224 {
1225         sprintf(p, "%s%d", driver->name, index + driver->name_base);
1226 }
1227
1228 /**
1229  *      tty_driver_lookup_tty() - find an existing tty, if any
1230  *      @driver: the driver for the tty
1231  *      @idx:    the minor number
1232  *
1233  *      Return the tty, if found or ERR_PTR() otherwise.
1234  *
1235  *      Locking: tty_mutex must be held. If tty is found, the mutex must
1236  *      be held until the 'fast-open' is also done. Will change once we
1237  *      have refcounting in the driver and per driver locking
1238  */
1239 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1240                 struct inode *inode, int idx)
1241 {
1242         if (driver->ops->lookup)
1243                 return driver->ops->lookup(driver, inode, idx);
1244
1245         return driver->ttys[idx];
1246 }
1247
1248 /**
1249  *      tty_init_termios        -  helper for termios setup
1250  *      @tty: the tty to set up
1251  *
1252  *      Initialise the termios structures for this tty. Thus runs under
1253  *      the tty_mutex currently so we can be relaxed about ordering.
1254  */
1255
1256 int tty_init_termios(struct tty_struct *tty)
1257 {
1258         struct ktermios *tp;
1259         int idx = tty->index;
1260
1261         tp = tty->driver->termios[idx];
1262         if (tp == NULL) {
1263                 tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
1264                 if (tp == NULL)
1265                         return -ENOMEM;
1266                 memcpy(tp, &tty->driver->init_termios,
1267                                                 sizeof(struct ktermios));
1268                 tty->driver->termios[idx] = tp;
1269         }
1270         tty->termios = tp;
1271         tty->termios_locked = tp + 1;
1272
1273         /* Compatibility until drivers always set this */
1274         tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1275         tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1276         return 0;
1277 }
1278 EXPORT_SYMBOL_GPL(tty_init_termios);
1279
1280 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1281 {
1282         int ret = tty_init_termios(tty);
1283         if (ret)
1284                 return ret;
1285
1286         tty_driver_kref_get(driver);
1287         tty->count++;
1288         driver->ttys[tty->index] = tty;
1289         return 0;
1290 }
1291 EXPORT_SYMBOL_GPL(tty_standard_install);
1292
1293 /**
1294  *      tty_driver_install_tty() - install a tty entry in the driver
1295  *      @driver: the driver for the tty
1296  *      @tty: the tty
1297  *
1298  *      Install a tty object into the driver tables. The tty->index field
1299  *      will be set by the time this is called. This method is responsible
1300  *      for ensuring any need additional structures are allocated and
1301  *      configured.
1302  *
1303  *      Locking: tty_mutex for now
1304  */
1305 static int tty_driver_install_tty(struct tty_driver *driver,
1306                                                 struct tty_struct *tty)
1307 {
1308         return driver->ops->install ? driver->ops->install(driver, tty) :
1309                 tty_standard_install(driver, tty);
1310 }
1311
1312 /**
1313  *      tty_driver_remove_tty() - remove a tty from the driver tables
1314  *      @driver: the driver for the tty
1315  *      @idx:    the minor number
1316  *
1317  *      Remvoe a tty object from the driver tables. The tty->index field
1318  *      will be set by the time this is called.
1319  *
1320  *      Locking: tty_mutex for now
1321  */
1322 void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1323 {
1324         if (driver->ops->remove)
1325                 driver->ops->remove(driver, tty);
1326         else
1327                 driver->ttys[tty->index] = NULL;
1328 }
1329
1330 /*
1331  *      tty_reopen()    - fast re-open of an open tty
1332  *      @tty    - the tty to open
1333  *
1334  *      Return 0 on success, -errno on error.
1335  *
1336  *      Locking: tty_mutex must be held from the time the tty was found
1337  *               till this open completes.
1338  */
1339 static int tty_reopen(struct tty_struct *tty)
1340 {
1341         struct tty_driver *driver = tty->driver;
1342
1343         if (test_bit(TTY_CLOSING, &tty->flags) ||
1344                         test_bit(TTY_HUPPING, &tty->flags) ||
1345                         test_bit(TTY_LDISC_CHANGING, &tty->flags))
1346                 return -EIO;
1347
1348         if (driver->type == TTY_DRIVER_TYPE_PTY &&
1349             driver->subtype == PTY_TYPE_MASTER) {
1350                 /*
1351                  * special case for PTY masters: only one open permitted,
1352                  * and the slave side open count is incremented as well.
1353                  */
1354                 if (tty->count)
1355                         return -EIO;
1356
1357                 tty->link->count++;
1358         }
1359         tty->count++;
1360
1361         mutex_lock(&tty->ldisc_mutex);
1362         WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1363         mutex_unlock(&tty->ldisc_mutex);
1364
1365         return 0;
1366 }
1367
1368 /**
1369  *      tty_init_dev            -       initialise a tty device
1370  *      @driver: tty driver we are opening a device on
1371  *      @idx: device index
1372  *      @ret_tty: returned tty structure
1373  *
1374  *      Prepare a tty device. This may not be a "new" clean device but
1375  *      could also be an active device. The pty drivers require special
1376  *      handling because of this.
1377  *
1378  *      Locking:
1379  *              The function is called under the tty_mutex, which
1380  *      protects us from the tty struct or driver itself going away.
1381  *
1382  *      On exit the tty device has the line discipline attached and
1383  *      a reference count of 1. If a pair was created for pty/tty use
1384  *      and the other was a pty master then it too has a reference count of 1.
1385  *
1386  * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1387  * failed open.  The new code protects the open with a mutex, so it's
1388  * really quite straightforward.  The mutex locking can probably be
1389  * relaxed for the (most common) case of reopening a tty.
1390  */
1391
1392 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1393 {
1394         struct tty_struct *tty;
1395         int retval;
1396
1397         /*
1398          * First time open is complex, especially for PTY devices.
1399          * This code guarantees that either everything succeeds and the
1400          * TTY is ready for operation, or else the table slots are vacated
1401          * and the allocated memory released.  (Except that the termios
1402          * and locked termios may be retained.)
1403          */
1404
1405         if (!try_module_get(driver->owner))
1406                 return ERR_PTR(-ENODEV);
1407
1408         tty = alloc_tty_struct();
1409         if (!tty) {
1410                 retval = -ENOMEM;
1411                 goto err_module_put;
1412         }
1413         initialize_tty_struct(tty, driver, idx);
1414
1415         retval = tty_driver_install_tty(driver, tty);
1416         if (retval < 0)
1417                 goto err_deinit_tty;
1418
1419         /*
1420          * Structures all installed ... call the ldisc open routines.
1421          * If we fail here just call release_tty to clean up.  No need
1422          * to decrement the use counts, as release_tty doesn't care.
1423          */
1424         retval = tty_ldisc_setup(tty, tty->link);
1425         if (retval)
1426                 goto err_release_tty;
1427         return tty;
1428
1429 err_deinit_tty:
1430         deinitialize_tty_struct(tty);
1431         free_tty_struct(tty);
1432 err_module_put:
1433         module_put(driver->owner);
1434         return ERR_PTR(retval);
1435
1436         /* call the tty release_tty routine to clean out this slot */
1437 err_release_tty:
1438         printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, "
1439                                  "clearing slot %d\n", idx);
1440         release_tty(tty, idx);
1441         return ERR_PTR(retval);
1442 }
1443
1444 void tty_free_termios(struct tty_struct *tty)
1445 {
1446         struct ktermios *tp;
1447         int idx = tty->index;
1448         /* Kill this flag and push into drivers for locking etc */
1449         if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
1450                 /* FIXME: Locking on ->termios array */
1451                 tp = tty->termios;
1452                 tty->driver->termios[idx] = NULL;
1453                 kfree(tp);
1454         }
1455 }
1456 EXPORT_SYMBOL(tty_free_termios);
1457
1458 void tty_shutdown(struct tty_struct *tty)
1459 {
1460         tty_driver_remove_tty(tty->driver, tty);
1461         tty_free_termios(tty);
1462 }
1463 EXPORT_SYMBOL(tty_shutdown);
1464
1465 /**
1466  *      release_one_tty         -       release tty structure memory
1467  *      @kref: kref of tty we are obliterating
1468  *
1469  *      Releases memory associated with a tty structure, and clears out the
1470  *      driver table slots. This function is called when a device is no longer
1471  *      in use. It also gets called when setup of a device fails.
1472  *
1473  *      Locking:
1474  *              tty_mutex - sometimes only
1475  *              takes the file list lock internally when working on the list
1476  *      of ttys that the driver keeps.
1477  *
1478  *      This method gets called from a work queue so that the driver private
1479  *      cleanup ops can sleep (needed for USB at least)
1480  */
1481 static void release_one_tty(struct work_struct *work)
1482 {
1483         struct tty_struct *tty =
1484                 container_of(work, struct tty_struct, hangup_work);
1485         struct tty_driver *driver = tty->driver;
1486
1487         if (tty->ops->cleanup)
1488                 tty->ops->cleanup(tty);
1489
1490         tty->magic = 0;
1491         tty_driver_kref_put(driver);
1492         module_put(driver->owner);
1493
1494         spin_lock(&tty_files_lock);
1495         list_del_init(&tty->tty_files);
1496         spin_unlock(&tty_files_lock);
1497
1498         put_pid(tty->pgrp);
1499         put_pid(tty->session);
1500         free_tty_struct(tty);
1501 }
1502
1503 static void queue_release_one_tty(struct kref *kref)
1504 {
1505         struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1506
1507         if (tty->ops->shutdown)
1508                 tty->ops->shutdown(tty);
1509         else
1510                 tty_shutdown(tty);
1511
1512         /* The hangup queue is now free so we can reuse it rather than
1513            waste a chunk of memory for each port */
1514         INIT_WORK(&tty->hangup_work, release_one_tty);
1515         schedule_work(&tty->hangup_work);
1516 }
1517
1518 /**
1519  *      tty_kref_put            -       release a tty kref
1520  *      @tty: tty device
1521  *
1522  *      Release a reference to a tty device and if need be let the kref
1523  *      layer destruct the object for us
1524  */
1525
1526 void tty_kref_put(struct tty_struct *tty)
1527 {
1528         if (tty)
1529                 kref_put(&tty->kref, queue_release_one_tty);
1530 }
1531 EXPORT_SYMBOL(tty_kref_put);
1532
1533 /**
1534  *      release_tty             -       release tty structure memory
1535  *
1536  *      Release both @tty and a possible linked partner (think pty pair),
1537  *      and decrement the refcount of the backing module.
1538  *
1539  *      Locking:
1540  *              tty_mutex - sometimes only
1541  *              takes the file list lock internally when working on the list
1542  *      of ttys that the driver keeps.
1543  *              FIXME: should we require tty_mutex is held here ??
1544  *
1545  */
1546 static void release_tty(struct tty_struct *tty, int idx)
1547 {
1548         /* This should always be true but check for the moment */
1549         WARN_ON(tty->index != idx);
1550
1551         if (tty->link)
1552                 tty_kref_put(tty->link);
1553         tty_kref_put(tty);
1554 }
1555
1556 /**
1557  *      tty_release_checks - check a tty before real release
1558  *      @tty: tty to check
1559  *      @o_tty: link of @tty (if any)
1560  *      @idx: index of the tty
1561  *
1562  *      Performs some paranoid checking before true release of the @tty.
1563  *      This is a no-op unless TTY_PARANOIA_CHECK is defined.
1564  */
1565 static int tty_release_checks(struct tty_struct *tty, struct tty_struct *o_tty,
1566                 int idx)
1567 {
1568 #ifdef TTY_PARANOIA_CHECK
1569         if (idx < 0 || idx >= tty->driver->num) {
1570                 printk(KERN_DEBUG "%s: bad idx when trying to free (%s)\n",
1571                                 __func__, tty->name);
1572                 return -1;
1573         }
1574
1575         /* not much to check for devpts */
1576         if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1577                 return 0;
1578
1579         if (tty != tty->driver->ttys[idx]) {
1580                 printk(KERN_DEBUG "%s: driver.table[%d] not tty for (%s)\n",
1581                                 __func__, idx, tty->name);
1582                 return -1;
1583         }
1584         if (tty->termios != tty->driver->termios[idx]) {
1585                 printk(KERN_DEBUG "%s: driver.termios[%d] not termios for (%s)\n",
1586                                 __func__, idx, tty->name);
1587                 return -1;
1588         }
1589         if (tty->driver->other) {
1590                 if (o_tty != tty->driver->other->ttys[idx]) {
1591                         printk(KERN_DEBUG "%s: other->table[%d] not o_tty for (%s)\n",
1592                                         __func__, idx, tty->name);
1593                         return -1;
1594                 }
1595                 if (o_tty->termios != tty->driver->other->termios[idx]) {
1596                         printk(KERN_DEBUG "%s: other->termios[%d] not o_termios for (%s)\n",
1597                                         __func__, idx, tty->name);
1598                         return -1;
1599                 }
1600                 if (o_tty->link != tty) {
1601                         printk(KERN_DEBUG "%s: bad pty pointers\n", __func__);
1602                         return -1;
1603                 }
1604         }
1605 #endif
1606         return 0;
1607 }
1608
1609 /**
1610  *      tty_release             -       vfs callback for close
1611  *      @inode: inode of tty
1612  *      @filp: file pointer for handle to tty
1613  *
1614  *      Called the last time each file handle is closed that references
1615  *      this tty. There may however be several such references.
1616  *
1617  *      Locking:
1618  *              Takes bkl. See tty_release_dev
1619  *
1620  * Even releasing the tty structures is a tricky business.. We have
1621  * to be very careful that the structures are all released at the
1622  * same time, as interrupts might otherwise get the wrong pointers.
1623  *
1624  * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1625  * lead to double frees or releasing memory still in use.
1626  */
1627
1628 int tty_release(struct inode *inode, struct file *filp)
1629 {
1630         struct tty_struct *tty = file_tty(filp);
1631         struct tty_struct *o_tty;
1632         int     pty_master, tty_closing, o_tty_closing, do_sleep;
1633         int     devpts;
1634         int     idx;
1635         char    buf[64];
1636
1637         if (tty_paranoia_check(tty, inode, __func__))
1638                 return 0;
1639
1640         tty_lock();
1641         check_tty_count(tty, __func__);
1642
1643         __tty_fasync(-1, filp, 0);
1644
1645         idx = tty->index;
1646         pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1647                       tty->driver->subtype == PTY_TYPE_MASTER);
1648         devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1649         o_tty = tty->link;
1650
1651         if (tty_release_checks(tty, o_tty, idx)) {
1652                 tty_unlock();
1653                 return 0;
1654         }
1655
1656 #ifdef TTY_DEBUG_HANGUP
1657         printk(KERN_DEBUG "%s: %s (tty count=%d)...\n", __func__,
1658                         tty_name(tty, buf), tty->count);
1659 #endif
1660
1661         if (tty->ops->close)
1662                 tty->ops->close(tty, filp);
1663
1664         tty_unlock();
1665         /*
1666          * Sanity check: if tty->count is going to zero, there shouldn't be
1667          * any waiters on tty->read_wait or tty->write_wait.  We test the
1668          * wait queues and kick everyone out _before_ actually starting to
1669          * close.  This ensures that we won't block while releasing the tty
1670          * structure.
1671          *
1672          * The test for the o_tty closing is necessary, since the master and
1673          * slave sides may close in any order.  If the slave side closes out
1674          * first, its count will be one, since the master side holds an open.
1675          * Thus this test wouldn't be triggered at the time the slave closes,
1676          * so we do it now.
1677          *
1678          * Note that it's possible for the tty to be opened again while we're
1679          * flushing out waiters.  By recalculating the closing flags before
1680          * each iteration we avoid any problems.
1681          */
1682         while (1) {
1683                 /* Guard against races with tty->count changes elsewhere and
1684                    opens on /dev/tty */
1685
1686                 mutex_lock(&tty_mutex);
1687                 tty_lock();
1688                 tty_closing = tty->count <= 1;
1689                 o_tty_closing = o_tty &&
1690                         (o_tty->count <= (pty_master ? 1 : 0));
1691                 do_sleep = 0;
1692
1693                 if (tty_closing) {
1694                         if (waitqueue_active(&tty->read_wait)) {
1695                                 wake_up_poll(&tty->read_wait, POLLIN);
1696                                 do_sleep++;
1697                         }
1698                         if (waitqueue_active(&tty->write_wait)) {
1699                                 wake_up_poll(&tty->write_wait, POLLOUT);
1700                                 do_sleep++;
1701                         }
1702                 }
1703                 if (o_tty_closing) {
1704                         if (waitqueue_active(&o_tty->read_wait)) {
1705                                 wake_up_poll(&o_tty->read_wait, POLLIN);
1706                                 do_sleep++;
1707                         }
1708                         if (waitqueue_active(&o_tty->write_wait)) {
1709                                 wake_up_poll(&o_tty->write_wait, POLLOUT);
1710                                 do_sleep++;
1711                         }
1712                 }
1713                 if (!do_sleep)
1714                         break;
1715
1716                 printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",
1717                                 __func__, tty_name(tty, buf));
1718                 tty_unlock();
1719                 mutex_unlock(&tty_mutex);
1720                 schedule();
1721         }
1722
1723         /*
1724          * The closing flags are now consistent with the open counts on
1725          * both sides, and we've completed the last operation that could
1726          * block, so it's safe to proceed with closing.
1727          */
1728         if (pty_master) {
1729                 if (--o_tty->count < 0) {
1730                         printk(KERN_WARNING "%s: bad pty slave count (%d) for %s\n",
1731                                 __func__, o_tty->count, tty_name(o_tty, buf));
1732                         o_tty->count = 0;
1733                 }
1734         }
1735         if (--tty->count < 0) {
1736                 printk(KERN_WARNING "%s: bad tty->count (%d) for %s\n",
1737                                 __func__, tty->count, tty_name(tty, buf));
1738                 tty->count = 0;
1739         }
1740
1741         /*
1742          * We've decremented tty->count, so we need to remove this file
1743          * descriptor off the tty->tty_files list; this serves two
1744          * purposes:
1745          *  - check_tty_count sees the correct number of file descriptors
1746          *    associated with this tty.
1747          *  - do_tty_hangup no longer sees this file descriptor as
1748          *    something that needs to be handled for hangups.
1749          */
1750         tty_del_file(filp);
1751
1752         /*
1753          * Perform some housekeeping before deciding whether to return.
1754          *
1755          * Set the TTY_CLOSING flag if this was the last open.  In the
1756          * case of a pty we may have to wait around for the other side
1757          * to close, and TTY_CLOSING makes sure we can't be reopened.
1758          */
1759         if (tty_closing)
1760                 set_bit(TTY_CLOSING, &tty->flags);
1761         if (o_tty_closing)
1762                 set_bit(TTY_CLOSING, &o_tty->flags);
1763
1764         /*
1765          * If _either_ side is closing, make sure there aren't any
1766          * processes that still think tty or o_tty is their controlling
1767          * tty.
1768          */
1769         if (tty_closing || o_tty_closing) {
1770                 read_lock(&tasklist_lock);
1771                 session_clear_tty(tty->session);
1772                 if (o_tty)
1773                         session_clear_tty(o_tty->session);
1774                 read_unlock(&tasklist_lock);
1775         }
1776
1777         mutex_unlock(&tty_mutex);
1778
1779         /* check whether both sides are closing ... */
1780         if (!tty_closing || (o_tty && !o_tty_closing)) {
1781                 tty_unlock();
1782                 return 0;
1783         }
1784
1785 #ifdef TTY_DEBUG_HANGUP
1786         printk(KERN_DEBUG "%s: freeing tty structure...\n", __func__);
1787 #endif
1788         /*
1789          * Ask the line discipline code to release its structures
1790          */
1791         tty_ldisc_release(tty, o_tty);
1792         /*
1793          * The release_tty function takes care of the details of clearing
1794          * the slots and preserving the termios structure.
1795          */
1796         release_tty(tty, idx);
1797
1798         /* Make this pty number available for reallocation */
1799         if (devpts)
1800                 devpts_kill_index(inode, idx);
1801         tty_unlock();
1802         return 0;
1803 }
1804
1805 /**
1806  *      tty_open_current_tty - get tty of current task for open
1807  *      @device: device number
1808  *      @filp: file pointer to tty
1809  *      @return: tty of the current task iff @device is /dev/tty
1810  *
1811  *      We cannot return driver and index like for the other nodes because
1812  *      devpts will not work then. It expects inodes to be from devpts FS.
1813  */
1814 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1815 {
1816         struct tty_struct *tty;
1817
1818         if (device != MKDEV(TTYAUX_MAJOR, 0))
1819                 return NULL;
1820
1821         tty = get_current_tty();
1822         if (!tty)
1823                 return ERR_PTR(-ENXIO);
1824
1825         filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1826         /* noctty = 1; */
1827         tty_kref_put(tty);
1828         /* FIXME: we put a reference and return a TTY! */
1829         return tty;
1830 }
1831
1832 /**
1833  *      tty_lookup_driver - lookup a tty driver for a given device file
1834  *      @device: device number
1835  *      @filp: file pointer to tty
1836  *      @noctty: set if the device should not become a controlling tty
1837  *      @index: index for the device in the @return driver
1838  *      @return: driver for this inode (with increased refcount)
1839  *
1840  *      If @return is not erroneous, the caller is responsible to decrement the
1841  *      refcount by tty_driver_kref_put.
1842  *
1843  *      Locking: tty_mutex protects get_tty_driver
1844  */
1845 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1846                 int *noctty, int *index)
1847 {
1848         struct tty_driver *driver;
1849
1850         switch (device) {
1851 #ifdef CONFIG_VT
1852         case MKDEV(TTY_MAJOR, 0): {
1853                 extern struct tty_driver *console_driver;
1854                 driver = tty_driver_kref_get(console_driver);
1855                 *index = fg_console;
1856                 *noctty = 1;
1857                 break;
1858         }
1859 #endif
1860         case MKDEV(TTYAUX_MAJOR, 1): {
1861                 struct tty_driver *console_driver = console_device(index);
1862                 if (console_driver) {
1863                         driver = tty_driver_kref_get(console_driver);
1864                         if (driver) {
1865                                 /* Don't let /dev/console block */
1866                                 filp->f_flags |= O_NONBLOCK;
1867                                 *noctty = 1;
1868                                 break;
1869                         }
1870                 }
1871                 return ERR_PTR(-ENODEV);
1872         }
1873         default:
1874                 driver = get_tty_driver(device, index);
1875                 if (!driver)
1876                         return ERR_PTR(-ENODEV);
1877                 break;
1878         }
1879         return driver;
1880 }
1881
1882 /**
1883  *      tty_open                -       open a tty device
1884  *      @inode: inode of device file
1885  *      @filp: file pointer to tty
1886  *
1887  *      tty_open and tty_release keep up the tty count that contains the
1888  *      number of opens done on a tty. We cannot use the inode-count, as
1889  *      different inodes might point to the same tty.
1890  *
1891  *      Open-counting is needed for pty masters, as well as for keeping
1892  *      track of serial lines: DTR is dropped when the last close happens.
1893  *      (This is not done solely through tty->count, now.  - Ted 1/27/92)
1894  *
1895  *      The termios state of a pty is reset on first open so that
1896  *      settings don't persist across reuse.
1897  *
1898  *      Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
1899  *               tty->count should protect the rest.
1900  *               ->siglock protects ->signal/->sighand
1901  */
1902
1903 static int tty_open(struct inode *inode, struct file *filp)
1904 {
1905         struct tty_struct *tty;
1906         int noctty, retval;
1907         struct tty_driver *driver = NULL;
1908         int index;
1909         dev_t device = inode->i_rdev;
1910         unsigned saved_flags = filp->f_flags;
1911
1912         nonseekable_open(inode, filp);
1913
1914 retry_open:
1915         retval = tty_alloc_file(filp);
1916         if (retval)
1917                 return -ENOMEM;
1918
1919         noctty = filp->f_flags & O_NOCTTY;
1920         index  = -1;
1921         retval = 0;
1922
1923         mutex_lock(&tty_mutex);
1924         tty_lock();
1925
1926         tty = tty_open_current_tty(device, filp);
1927         if (IS_ERR(tty)) {
1928                 retval = PTR_ERR(tty);
1929                 goto err_unlock;
1930         } else if (!tty) {
1931                 driver = tty_lookup_driver(device, filp, &noctty, &index);
1932                 if (IS_ERR(driver)) {
1933                         retval = PTR_ERR(driver);
1934                         goto err_unlock;
1935                 }
1936
1937                 /* check whether we're reopening an existing tty */
1938                 tty = tty_driver_lookup_tty(driver, inode, index);
1939                 if (IS_ERR(tty)) {
1940                         retval = PTR_ERR(tty);
1941                         goto err_unlock;
1942                 }
1943         }
1944
1945         if (tty) {
1946                 retval = tty_reopen(tty);
1947                 if (retval)
1948                         tty = ERR_PTR(retval);
1949         } else
1950                 tty = tty_init_dev(driver, index);
1951
1952         mutex_unlock(&tty_mutex);
1953         if (driver)
1954                 tty_driver_kref_put(driver);
1955         if (IS_ERR(tty)) {
1956                 tty_unlock();
1957                 retval = PTR_ERR(tty);
1958                 goto err_file;
1959         }
1960
1961         tty_add_file(tty, filp);
1962
1963         check_tty_count(tty, __func__);
1964         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1965             tty->driver->subtype == PTY_TYPE_MASTER)
1966                 noctty = 1;
1967 #ifdef TTY_DEBUG_HANGUP
1968         printk(KERN_DEBUG "%s: opening %s...\n", __func__, tty->name);
1969 #endif
1970         if (tty->ops->open)
1971                 retval = tty->ops->open(tty, filp);
1972         else
1973                 retval = -ENODEV;
1974         filp->f_flags = saved_flags;
1975
1976         if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
1977                                                 !capable(CAP_SYS_ADMIN))
1978                 retval = -EBUSY;
1979
1980         if (retval) {
1981 #ifdef TTY_DEBUG_HANGUP
1982                 printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,
1983                                 retval, tty->name);
1984 #endif
1985                 tty_unlock(); /* need to call tty_release without BTM */
1986                 tty_release(inode, filp);
1987                 if (retval != -ERESTARTSYS)
1988                         return retval;
1989
1990                 if (signal_pending(current))
1991                         return retval;
1992
1993                 schedule();
1994                 /*
1995                  * Need to reset f_op in case a hangup happened.
1996                  */
1997                 tty_lock();
1998                 if (filp->f_op == &hung_up_tty_fops)
1999                         filp->f_op = &tty_fops;
2000                 tty_unlock();
2001                 goto retry_open;
2002         }
2003         tty_unlock();
2004
2005
2006         mutex_lock(&tty_mutex);
2007         tty_lock();
2008         spin_lock_irq(&current->sighand->siglock);
2009         if (!noctty &&
2010             current->signal->leader &&
2011             !current->signal->tty &&
2012             tty->session == NULL)
2013                 __proc_set_tty(current, tty);
2014         spin_unlock_irq(&current->sighand->siglock);
2015         tty_unlock();
2016         mutex_unlock(&tty_mutex);
2017         return 0;
2018 err_unlock:
2019         tty_unlock();
2020         mutex_unlock(&tty_mutex);
2021         /* after locks to avoid deadlock */
2022         if (!IS_ERR_OR_NULL(driver))
2023                 tty_driver_kref_put(driver);
2024 err_file:
2025         tty_free_file(filp);
2026         return retval;
2027 }
2028
2029
2030
2031 /**
2032  *      tty_poll        -       check tty status
2033  *      @filp: file being polled
2034  *      @wait: poll wait structures to update
2035  *
2036  *      Call the line discipline polling method to obtain the poll
2037  *      status of the device.
2038  *
2039  *      Locking: locks called line discipline but ldisc poll method
2040  *      may be re-entered freely by other callers.
2041  */
2042
2043 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2044 {
2045         struct tty_struct *tty = file_tty(filp);
2046         struct tty_ldisc *ld;
2047         int ret = 0;
2048
2049         if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2050                 return 0;
2051
2052         ld = tty_ldisc_ref_wait(tty);
2053         if (ld->ops->poll)
2054                 ret = (ld->ops->poll)(tty, filp, wait);
2055         tty_ldisc_deref(ld);
2056         return ret;
2057 }
2058
2059 static int __tty_fasync(int fd, struct file *filp, int on)
2060 {
2061         struct tty_struct *tty = file_tty(filp);
2062         unsigned long flags;
2063         int retval = 0;
2064
2065         if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2066                 goto out;
2067
2068         retval = fasync_helper(fd, filp, on, &tty->fasync);
2069         if (retval <= 0)
2070                 goto out;
2071
2072         if (on) {
2073                 enum pid_type type;
2074                 struct pid *pid;
2075                 if (!waitqueue_active(&tty->read_wait))
2076                         tty->minimum_to_wake = 1;
2077                 spin_lock_irqsave(&tty->ctrl_lock, flags);
2078                 if (tty->pgrp) {
2079                         pid = tty->pgrp;
2080                         type = PIDTYPE_PGID;
2081                 } else {
2082                         pid = task_pid(current);
2083                         type = PIDTYPE_PID;
2084                 }
2085                 get_pid(pid);
2086                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2087                 retval = __f_setown(filp, pid, type, 0);
2088                 put_pid(pid);
2089                 if (retval)
2090                         goto out;
2091         } else {
2092                 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2093                         tty->minimum_to_wake = N_TTY_BUF_SIZE;
2094         }
2095         retval = 0;
2096 out:
2097         return retval;
2098 }
2099
2100 static int tty_fasync(int fd, struct file *filp, int on)
2101 {
2102         int retval;
2103         tty_lock();
2104         retval = __tty_fasync(fd, filp, on);
2105         tty_unlock();
2106         return retval;
2107 }
2108
2109 /**
2110  *      tiocsti                 -       fake input character
2111  *      @tty: tty to fake input into
2112  *      @p: pointer to character
2113  *
2114  *      Fake input to a tty device. Does the necessary locking and
2115  *      input management.
2116  *
2117  *      FIXME: does not honour flow control ??
2118  *
2119  *      Locking:
2120  *              Called functions take tty_ldisc_lock
2121  *              current->signal->tty check is safe without locks
2122  *
2123  *      FIXME: may race normal receive processing
2124  */
2125
2126 static int tiocsti(struct tty_struct *tty, char __user *p)
2127 {
2128         char ch, mbz = 0;
2129         struct tty_ldisc *ld;
2130
2131         if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2132                 return -EPERM;
2133         if (get_user(ch, p))
2134                 return -EFAULT;
2135         tty_audit_tiocsti(tty, ch);
2136         ld = tty_ldisc_ref_wait(tty);
2137         ld->ops->receive_buf(tty, &ch, &mbz, 1);
2138         tty_ldisc_deref(ld);
2139         return 0;
2140 }
2141
2142 /**
2143  *      tiocgwinsz              -       implement window query ioctl
2144  *      @tty; tty
2145  *      @arg: user buffer for result
2146  *
2147  *      Copies the kernel idea of the window size into the user buffer.
2148  *
2149  *      Locking: tty->termios_mutex is taken to ensure the winsize data
2150  *              is consistent.
2151  */
2152
2153 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2154 {
2155         int err;
2156
2157         mutex_lock(&tty->termios_mutex);
2158         err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2159         mutex_unlock(&tty->termios_mutex);
2160
2161         return err ? -EFAULT: 0;
2162 }
2163
2164 /**
2165  *      tty_do_resize           -       resize event
2166  *      @tty: tty being resized
2167  *      @rows: rows (character)
2168  *      @cols: cols (character)
2169  *
2170  *      Update the termios variables and send the necessary signals to
2171  *      peform a terminal resize correctly
2172  */
2173
2174 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2175 {
2176         struct pid *pgrp;
2177         unsigned long flags;
2178
2179         /* Lock the tty */
2180         mutex_lock(&tty->termios_mutex);
2181         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2182                 goto done;
2183         /* Get the PID values and reference them so we can
2184            avoid holding the tty ctrl lock while sending signals */
2185         spin_lock_irqsave(&tty->ctrl_lock, flags);
2186         pgrp = get_pid(tty->pgrp);
2187         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2188
2189         if (pgrp)
2190                 kill_pgrp(pgrp, SIGWINCH, 1);
2191         put_pid(pgrp);
2192
2193         tty->winsize = *ws;
2194 done:
2195         mutex_unlock(&tty->termios_mutex);
2196         return 0;
2197 }
2198
2199 /**
2200  *      tiocswinsz              -       implement window size set ioctl
2201  *      @tty; tty side of tty
2202  *      @arg: user buffer for result
2203  *
2204  *      Copies the user idea of the window size to the kernel. Traditionally
2205  *      this is just advisory information but for the Linux console it
2206  *      actually has driver level meaning and triggers a VC resize.
2207  *
2208  *      Locking:
2209  *              Driver dependent. The default do_resize method takes the
2210  *      tty termios mutex and ctrl_lock. The console takes its own lock
2211  *      then calls into the default method.
2212  */
2213
2214 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2215 {
2216         struct winsize tmp_ws;
2217         if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2218                 return -EFAULT;
2219
2220         if (tty->ops->resize)
2221                 return tty->ops->resize(tty, &tmp_ws);
2222         else
2223                 return tty_do_resize(tty, &tmp_ws);
2224 }
2225
2226 /**
2227  *      tioccons        -       allow admin to move logical console
2228  *      @file: the file to become console
2229  *
2230  *      Allow the administrator to move the redirected console device
2231  *
2232  *      Locking: uses redirect_lock to guard the redirect information
2233  */
2234
2235 static int tioccons(struct file *file)
2236 {
2237         if (!capable(CAP_SYS_ADMIN))
2238                 return -EPERM;
2239         if (file->f_op->write == redirected_tty_write) {
2240                 struct file *f;
2241                 spin_lock(&redirect_lock);
2242                 f = redirect;
2243                 redirect = NULL;
2244                 spin_unlock(&redirect_lock);
2245                 if (f)
2246                         fput(f);
2247                 return 0;
2248         }
2249         spin_lock(&redirect_lock);
2250         if (redirect) {
2251                 spin_unlock(&redirect_lock);
2252                 return -EBUSY;
2253         }
2254         get_file(file);
2255         redirect = file;
2256         spin_unlock(&redirect_lock);
2257         return 0;
2258 }
2259
2260 /**
2261  *      fionbio         -       non blocking ioctl
2262  *      @file: file to set blocking value
2263  *      @p: user parameter
2264  *
2265  *      Historical tty interfaces had a blocking control ioctl before
2266  *      the generic functionality existed. This piece of history is preserved
2267  *      in the expected tty API of posix OS's.
2268  *
2269  *      Locking: none, the open file handle ensures it won't go away.
2270  */
2271
2272 static int fionbio(struct file *file, int __user *p)
2273 {
2274         int nonblock;
2275
2276         if (get_user(nonblock, p))
2277                 return -EFAULT;
2278
2279         spin_lock(&file->f_lock);
2280         if (nonblock)
2281                 file->f_flags |= O_NONBLOCK;
2282         else
2283                 file->f_flags &= ~O_NONBLOCK;
2284         spin_unlock(&file->f_lock);
2285         return 0;
2286 }
2287
2288 /**
2289  *      tiocsctty       -       set controlling tty
2290  *      @tty: tty structure
2291  *      @arg: user argument
2292  *
2293  *      This ioctl is used to manage job control. It permits a session
2294  *      leader to set this tty as the controlling tty for the session.
2295  *
2296  *      Locking:
2297  *              Takes tty_mutex() to protect tty instance
2298  *              Takes tasklist_lock internally to walk sessions
2299  *              Takes ->siglock() when updating signal->tty
2300  */
2301
2302 static int tiocsctty(struct tty_struct *tty, int arg)
2303 {
2304         int ret = 0;
2305         if (current->signal->leader && (task_session(current) == tty->session))
2306                 return ret;
2307
2308         mutex_lock(&tty_mutex);
2309         /*
2310          * The process must be a session leader and
2311          * not have a controlling tty already.
2312          */
2313         if (!current->signal->leader || current->signal->tty) {
2314                 ret = -EPERM;
2315                 goto unlock;
2316         }
2317
2318         if (tty->session) {
2319                 /*
2320                  * This tty is already the controlling
2321                  * tty for another session group!
2322                  */
2323                 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2324                         /*
2325                          * Steal it away
2326                          */
2327                         read_lock(&tasklist_lock);
2328                         session_clear_tty(tty->session);
2329                         read_unlock(&tasklist_lock);
2330                 } else {
2331                         ret = -EPERM;
2332                         goto unlock;
2333                 }
2334         }
2335         proc_set_tty(current, tty);
2336 unlock:
2337         mutex_unlock(&tty_mutex);
2338         return ret;
2339 }
2340
2341 /**
2342  *      tty_get_pgrp    -       return a ref counted pgrp pid
2343  *      @tty: tty to read
2344  *
2345  *      Returns a refcounted instance of the pid struct for the process
2346  *      group controlling the tty.
2347  */
2348
2349 struct pid *tty_get_pgrp(struct tty_struct *tty)
2350 {
2351         unsigned long flags;
2352         struct pid *pgrp;
2353
2354         spin_lock_irqsave(&tty->ctrl_lock, flags);
2355         pgrp = get_pid(tty->pgrp);
2356         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2357
2358         return pgrp;
2359 }
2360 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2361
2362 /**
2363  *      tiocgpgrp               -       get process group
2364  *      @tty: tty passed by user
2365  *      @real_tty: tty side of the tty passed by the user if a pty else the tty
2366  *      @p: returned pid
2367  *
2368  *      Obtain the process group of the tty. If there is no process group
2369  *      return an error.
2370  *
2371  *      Locking: none. Reference to current->signal->tty is safe.
2372  */
2373
2374 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2375 {
2376         struct pid *pid;
2377         int ret;
2378         /*
2379          * (tty == real_tty) is a cheap way of
2380          * testing if the tty is NOT a master pty.
2381          */
2382         if (tty == real_tty && current->signal->tty != real_tty)
2383                 return -ENOTTY;
2384         pid = tty_get_pgrp(real_tty);
2385         ret =  put_user(pid_vnr(pid), p);
2386         put_pid(pid);
2387         return ret;
2388 }
2389
2390 /**
2391  *      tiocspgrp               -       attempt to set process group
2392  *      @tty: tty passed by user
2393  *      @real_tty: tty side device matching tty passed by user
2394  *      @p: pid pointer
2395  *
2396  *      Set the process group of the tty to the session passed. Only
2397  *      permitted where the tty session is our session.
2398  *
2399  *      Locking: RCU, ctrl lock
2400  */
2401
2402 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2403 {
2404         struct pid *pgrp;
2405         pid_t pgrp_nr;
2406         int retval = tty_check_change(real_tty);
2407         unsigned long flags;
2408
2409         if (retval == -EIO)
2410                 return -ENOTTY;
2411         if (retval)
2412                 return retval;
2413         if (!current->signal->tty ||
2414             (current->signal->tty != real_tty) ||
2415             (real_tty->session != task_session(current)))
2416                 return -ENOTTY;
2417         if (get_user(pgrp_nr, p))
2418                 return -EFAULT;
2419         if (pgrp_nr < 0)
2420                 return -EINVAL;
2421         rcu_read_lock();
2422         pgrp = find_vpid(pgrp_nr);
2423         retval = -ESRCH;
2424         if (!pgrp)
2425                 goto out_unlock;
2426         retval = -EPERM;
2427         if (session_of_pgrp(pgrp) != task_session(current))
2428                 goto out_unlock;
2429         retval = 0;
2430         spin_lock_irqsave(&tty->ctrl_lock, flags);
2431         put_pid(real_tty->pgrp);
2432         real_tty->pgrp = get_pid(pgrp);
2433         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2434 out_unlock:
2435         rcu_read_unlock();
2436         return retval;
2437 }
2438
2439 /**
2440  *      tiocgsid                -       get session id
2441  *      @tty: tty passed by user
2442  *      @real_tty: tty side of the tty passed by the user if a pty else the tty
2443  *      @p: pointer to returned session id
2444  *
2445  *      Obtain the session id of the tty. If there is no session
2446  *      return an error.
2447  *
2448  *      Locking: none. Reference to current->signal->tty is safe.
2449  */
2450
2451 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2452 {
2453         /*
2454          * (tty == real_tty) is a cheap way of
2455          * testing if the tty is NOT a master pty.
2456         */
2457         if (tty == real_tty && current->signal->tty != real_tty)
2458                 return -ENOTTY;
2459         if (!real_tty->session)
2460                 return -ENOTTY;
2461         return put_user(pid_vnr(real_tty->session), p);
2462 }
2463
2464 /**
2465  *      tiocsetd        -       set line discipline
2466  *      @tty: tty device
2467  *      @p: pointer to user data
2468  *
2469  *      Set the line discipline according to user request.
2470  *
2471  *      Locking: see tty_set_ldisc, this function is just a helper
2472  */
2473
2474 static int tiocsetd(struct tty_struct *tty, int __user *p)
2475 {
2476         int ldisc;
2477         int ret;
2478
2479         if (get_user(ldisc, p))
2480                 return -EFAULT;
2481
2482         ret = tty_set_ldisc(tty, ldisc);
2483
2484         return ret;
2485 }
2486
2487 /**
2488  *      send_break      -       performed time break
2489  *      @tty: device to break on
2490  *      @duration: timeout in mS
2491  *
2492  *      Perform a timed break on hardware that lacks its own driver level
2493  *      timed break functionality.
2494  *
2495  *      Locking:
2496  *              atomic_write_lock serializes
2497  *
2498  */
2499
2500 static int send_break(struct tty_struct *tty, unsigned int duration)
2501 {
2502         int retval;
2503
2504         if (tty->ops->break_ctl == NULL)
2505                 return 0;
2506
2507         if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2508                 retval = tty->ops->break_ctl(tty, duration);
2509         else {
2510                 /* Do the work ourselves */
2511                 if (tty_write_lock(tty, 0) < 0)
2512                         return -EINTR;
2513                 retval = tty->ops->break_ctl(tty, -1);
2514                 if (retval)
2515                         goto out;
2516                 if (!signal_pending(current))
2517                         msleep_interruptible(duration);
2518                 retval = tty->ops->break_ctl(tty, 0);
2519 out:
2520                 tty_write_unlock(tty);
2521                 if (signal_pending(current))
2522                         retval = -EINTR;
2523         }
2524         return retval;
2525 }
2526
2527 /**
2528  *      tty_tiocmget            -       get modem status
2529  *      @tty: tty device
2530  *      @file: user file pointer
2531  *      @p: pointer to result
2532  *
2533  *      Obtain the modem status bits from the tty driver if the feature
2534  *      is supported. Return -EINVAL if it is not available.
2535  *
2536  *      Locking: none (up to the driver)
2537  */
2538
2539 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2540 {
2541         int retval = -EINVAL;
2542
2543         if (tty->ops->tiocmget) {
2544                 retval = tty->ops->tiocmget(tty);
2545
2546                 if (retval >= 0)
2547                         retval = put_user(retval, p);
2548         }
2549         return retval;
2550 }
2551
2552 /**
2553  *      tty_tiocmset            -       set modem status
2554  *      @tty: tty device
2555  *      @cmd: command - clear bits, set bits or set all
2556  *      @p: pointer to desired bits
2557  *
2558  *      Set the modem status bits from the tty driver if the feature
2559  *      is supported. Return -EINVAL if it is not available.
2560  *
2561  *      Locking: none (up to the driver)
2562  */
2563
2564 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2565              unsigned __user *p)
2566 {
2567         int retval;
2568         unsigned int set, clear, val;
2569
2570         if (tty->ops->tiocmset == NULL)
2571                 return -EINVAL;
2572
2573         retval = get_user(val, p);
2574         if (retval)
2575                 return retval;
2576         set = clear = 0;
2577         switch (cmd) {
2578         case TIOCMBIS:
2579                 set = val;
2580                 break;
2581         case TIOCMBIC:
2582                 clear = val;
2583                 break;
2584         case TIOCMSET:
2585                 set = val;
2586                 clear = ~val;
2587                 break;
2588         }
2589         set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2590         clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2591         return tty->ops->tiocmset(tty, set, clear);
2592 }
2593
2594 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2595 {
2596         int retval = -EINVAL;
2597         struct serial_icounter_struct icount;
2598         memset(&icount, 0, sizeof(icount));
2599         if (tty->ops->get_icount)
2600                 retval = tty->ops->get_icount(tty, &icount);
2601         if (retval != 0)
2602                 return retval;
2603         if (copy_to_user(arg, &icount, sizeof(icount)))
2604                 return -EFAULT;
2605         return 0;
2606 }
2607
2608 struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2609 {
2610         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2611             tty->driver->subtype == PTY_TYPE_MASTER)
2612                 tty = tty->link;
2613         return tty;
2614 }
2615 EXPORT_SYMBOL(tty_pair_get_tty);
2616
2617 struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)
2618 {
2619         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2620             tty->driver->subtype == PTY_TYPE_MASTER)
2621             return tty;
2622         return tty->link;
2623 }
2624 EXPORT_SYMBOL(tty_pair_get_pty);
2625
2626 /*
2627  * Split this up, as gcc can choke on it otherwise..
2628  */
2629 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2630 {
2631         struct tty_struct *tty = file_tty(file);
2632         struct tty_struct *real_tty;
2633         void __user *p = (void __user *)arg;
2634         int retval;
2635         struct tty_ldisc *ld;
2636         struct inode *inode = file->f_dentry->d_inode;
2637
2638         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2639                 return -EINVAL;
2640
2641         real_tty = tty_pair_get_tty(tty);
2642
2643         /*
2644          * Factor out some common prep work
2645          */
2646         switch (cmd) {
2647         case TIOCSETD:
2648         case TIOCSBRK:
2649         case TIOCCBRK:
2650         case TCSBRK:
2651         case TCSBRKP:
2652                 retval = tty_check_change(tty);
2653                 if (retval)
2654                         return retval;
2655                 if (cmd != TIOCCBRK) {
2656                         tty_wait_until_sent(tty, 0);
2657                         if (signal_pending(current))
2658                                 return -EINTR;
2659                 }
2660                 break;
2661         }
2662
2663         /*
2664          *      Now do the stuff.
2665          */
2666         switch (cmd) {
2667         case TIOCSTI:
2668                 return tiocsti(tty, p);
2669         case TIOCGWINSZ:
2670                 return tiocgwinsz(real_tty, p);
2671         case TIOCSWINSZ:
2672                 return tiocswinsz(real_tty, p);
2673         case TIOCCONS:
2674                 return real_tty != tty ? -EINVAL : tioccons(file);
2675         case FIONBIO:
2676                 return fionbio(file, p);
2677         case TIOCEXCL:
2678                 set_bit(TTY_EXCLUSIVE, &tty->flags);
2679                 return 0;
2680         case TIOCNXCL:
2681                 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2682                 return 0;
2683         case TIOCNOTTY:
2684                 if (current->signal->tty != tty)
2685                         return -ENOTTY;
2686                 no_tty();
2687                 return 0;
2688         case TIOCSCTTY:
2689                 return tiocsctty(tty, arg);
2690         case TIOCGPGRP:
2691                 return tiocgpgrp(tty, real_tty, p);
2692         case TIOCSPGRP:
2693                 return tiocspgrp(tty, real_tty, p);
2694         case TIOCGSID:
2695                 return tiocgsid(tty, real_tty, p);
2696         case TIOCGETD:
2697                 return put_user(tty->ldisc->ops->num, (int __user *)p);
2698         case TIOCSETD:
2699                 return tiocsetd(tty, p);
2700         case TIOCVHANGUP:
2701                 if (!capable(CAP_SYS_ADMIN))
2702                         return -EPERM;
2703                 tty_vhangup(tty);
2704                 return 0;
2705         case TIOCGDEV:
2706         {
2707                 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2708                 return put_user(ret, (unsigned int __user *)p);
2709         }
2710         /*
2711          * Break handling
2712          */
2713         case TIOCSBRK:  /* Turn break on, unconditionally */
2714                 if (tty->ops->break_ctl)
2715                         return tty->ops->break_ctl(tty, -1);
2716                 return 0;
2717         case TIOCCBRK:  /* Turn break off, unconditionally */
2718                 if (tty->ops->break_ctl)
2719                         return tty->ops->break_ctl(tty, 0);
2720                 return 0;
2721         case TCSBRK:   /* SVID version: non-zero arg --> no break */
2722                 /* non-zero arg means wait for all output data
2723                  * to be sent (performed above) but don't send break.
2724                  * This is used by the tcdrain() termios function.
2725                  */
2726                 if (!arg)
2727                         return send_break(tty, 250);
2728                 return 0;
2729         case TCSBRKP:   /* support for POSIX tcsendbreak() */
2730                 return send_break(tty, arg ? arg*100 : 250);
2731
2732         case TIOCMGET:
2733                 return tty_tiocmget(tty, p);
2734         case TIOCMSET:
2735         case TIOCMBIC:
2736         case TIOCMBIS:
2737                 return tty_tiocmset(tty, cmd, p);
2738         case TIOCGICOUNT:
2739                 retval = tty_tiocgicount(tty, p);
2740                 /* For the moment allow fall through to the old method */
2741                 if (retval != -EINVAL)
2742                         return retval;
2743                 break;
2744         case TCFLSH:
2745                 switch (arg) {
2746                 case TCIFLUSH:
2747                 case TCIOFLUSH:
2748                 /* flush tty buffer and allow ldisc to process ioctl */
2749                         tty_buffer_flush(tty);
2750                         break;
2751                 }
2752                 break;
2753         }
2754         if (tty->ops->ioctl) {
2755                 retval = (tty->ops->ioctl)(tty, cmd, arg);
2756                 if (retval != -ENOIOCTLCMD)
2757                         return retval;
2758         }
2759         ld = tty_ldisc_ref_wait(tty);
2760         retval = -EINVAL;
2761         if (ld->ops->ioctl) {
2762                 retval = ld->ops->ioctl(tty, file, cmd, arg);
2763                 if (retval == -ENOIOCTLCMD)
2764                         retval = -EINVAL;
2765         }
2766         tty_ldisc_deref(ld);
2767         return retval;
2768 }
2769
2770 #ifdef CONFIG_COMPAT
2771 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2772                                 unsigned long arg)
2773 {
2774         struct inode *inode = file->f_dentry->d_inode;
2775         struct tty_struct *tty = file_tty(file);
2776         struct tty_ldisc *ld;
2777         int retval = -ENOIOCTLCMD;
2778
2779         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2780                 return -EINVAL;
2781
2782         if (tty->ops->compat_ioctl) {
2783                 retval = (tty->ops->compat_ioctl)(tty, cmd, arg);
2784                 if (retval != -ENOIOCTLCMD)
2785                         return retval;
2786         }
2787
2788         ld = tty_ldisc_ref_wait(tty);
2789         if (ld->ops->compat_ioctl)
2790                 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2791         else
2792                 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
2793         tty_ldisc_deref(ld);
2794
2795         return retval;
2796 }
2797 #endif
2798
2799 /*
2800  * This implements the "Secure Attention Key" ---  the idea is to
2801  * prevent trojan horses by killing all processes associated with this
2802  * tty when the user hits the "Secure Attention Key".  Required for
2803  * super-paranoid applications --- see the Orange Book for more details.
2804  *
2805  * This code could be nicer; ideally it should send a HUP, wait a few
2806  * seconds, then send a INT, and then a KILL signal.  But you then
2807  * have to coordinate with the init process, since all processes associated
2808  * with the current tty must be dead before the new getty is allowed
2809  * to spawn.
2810  *
2811  * Now, if it would be correct ;-/ The current code has a nasty hole -
2812  * it doesn't catch files in flight. We may send the descriptor to ourselves
2813  * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2814  *
2815  * Nasty bug: do_SAK is being called in interrupt context.  This can
2816  * deadlock.  We punt it up to process context.  AKPM - 16Mar2001
2817  */
2818 void __do_SAK(struct tty_struct *tty)
2819 {
2820 #ifdef TTY_SOFT_SAK
2821         tty_hangup(tty);
2822 #else
2823         struct task_struct *g, *p;
2824         struct pid *session;
2825         int             i;
2826         struct file     *filp;
2827         struct fdtable *fdt;
2828
2829         if (!tty)
2830                 return;
2831         session = tty->session;
2832
2833         tty_ldisc_flush(tty);
2834
2835         tty_driver_flush_buffer(tty);
2836
2837         read_lock(&tasklist_lock);
2838         /* Kill the entire session */
2839         do_each_pid_task(session, PIDTYPE_SID, p) {
2840                 printk(KERN_NOTICE "SAK: killed process %d"
2841                         " (%s): task_session(p)==tty->session\n",
2842                         task_pid_nr(p), p->comm);
2843                 send_sig(SIGKILL, p, 1);
2844         } while_each_pid_task(session, PIDTYPE_SID, p);
2845         /* Now kill any processes that happen to have the
2846          * tty open.
2847          */
2848         do_each_thread(g, p) {
2849                 if (p->signal->tty == tty) {
2850                         printk(KERN_NOTICE "SAK: killed process %d"
2851                             " (%s): task_session(p)==tty->session\n",
2852                             task_pid_nr(p), p->comm);
2853                         send_sig(SIGKILL, p, 1);
2854                         continue;
2855                 }
2856                 task_lock(p);
2857                 if (p->files) {
2858                         /*
2859                          * We don't take a ref to the file, so we must
2860                          * hold ->file_lock instead.
2861                          */
2862                         spin_lock(&p->files->file_lock);
2863                         fdt = files_fdtable(p->files);
2864                         for (i = 0; i < fdt->max_fds; i++) {
2865                                 filp = fcheck_files(p->files, i);
2866                                 if (!filp)
2867                                         continue;
2868                                 if (filp->f_op->read == tty_read &&
2869                                     file_tty(filp) == tty) {
2870                                         printk(KERN_NOTICE "SAK: killed process %d"
2871                                             " (%s): fd#%d opened to the tty\n",
2872                                             task_pid_nr(p), p->comm, i);
2873                                         force_sig(SIGKILL, p);
2874                                         break;
2875                                 }
2876                         }
2877                         spin_unlock(&p->files->file_lock);
2878                 }
2879                 task_unlock(p);
2880         } while_each_thread(g, p);
2881         read_unlock(&tasklist_lock);
2882 #endif
2883 }
2884
2885 static void do_SAK_work(struct work_struct *work)
2886 {
2887         struct tty_struct *tty =
2888                 container_of(work, struct tty_struct, SAK_work);
2889         __do_SAK(tty);
2890 }
2891
2892 /*
2893  * The tq handling here is a little racy - tty->SAK_work may already be queued.
2894  * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2895  * the values which we write to it will be identical to the values which it
2896  * already has. --akpm
2897  */
2898 void do_SAK(struct tty_struct *tty)
2899 {
2900         if (!tty)
2901                 return;
2902         schedule_work(&tty->SAK_work);
2903 }
2904
2905 EXPORT_SYMBOL(do_SAK);
2906
2907 static int dev_match_devt(struct device *dev, void *data)
2908 {
2909         dev_t *devt = data;
2910         return dev->devt == *devt;
2911 }
2912
2913 /* Must put_device() after it's unused! */
2914 static struct device *tty_get_device(struct tty_struct *tty)
2915 {
2916         dev_t devt = tty_devnum(tty);
2917         return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2918 }
2919
2920
2921 /**
2922  *      initialize_tty_struct
2923  *      @tty: tty to initialize
2924  *
2925  *      This subroutine initializes a tty structure that has been newly
2926  *      allocated.
2927  *
2928  *      Locking: none - tty in question must not be exposed at this point
2929  */
2930
2931 void initialize_tty_struct(struct tty_struct *tty,
2932                 struct tty_driver *driver, int idx)
2933 {
2934         memset(tty, 0, sizeof(struct tty_struct));
2935         kref_init(&tty->kref);
2936         tty->magic = TTY_MAGIC;
2937         tty_ldisc_init(tty);
2938         tty->session = NULL;
2939         tty->pgrp = NULL;
2940         tty->overrun_time = jiffies;
2941         tty_buffer_init(tty);
2942         mutex_init(&tty->termios_mutex);
2943         mutex_init(&tty->ldisc_mutex);
2944         init_waitqueue_head(&tty->write_wait);
2945         init_waitqueue_head(&tty->read_wait);
2946         INIT_WORK(&tty->hangup_work, do_tty_hangup);
2947         mutex_init(&tty->atomic_read_lock);
2948         mutex_init(&tty->atomic_write_lock);
2949         mutex_init(&tty->output_lock);
2950         mutex_init(&tty->echo_lock);
2951         spin_lock_init(&tty->read_lock);
2952         spin_lock_init(&tty->ctrl_lock);
2953         INIT_LIST_HEAD(&tty->tty_files);
2954         INIT_WORK(&tty->SAK_work, do_SAK_work);
2955
2956         tty->driver = driver;
2957         tty->ops = driver->ops;
2958         tty->index = idx;
2959         tty_line_name(driver, idx, tty->name);
2960         tty->dev = tty_get_device(tty);
2961 }
2962
2963 /**
2964  *      deinitialize_tty_struct
2965  *      @tty: tty to deinitialize
2966  *
2967  *      This subroutine deinitializes a tty structure that has been newly
2968  *      allocated but tty_release cannot be called on that yet.
2969  *
2970  *      Locking: none - tty in question must not be exposed at this point
2971  */
2972 void deinitialize_tty_struct(struct tty_struct *tty)
2973 {
2974         tty_ldisc_deinit(tty);
2975 }
2976
2977 /**
2978  *      tty_put_char    -       write one character to a tty
2979  *      @tty: tty
2980  *      @ch: character
2981  *
2982  *      Write one byte to the tty using the provided put_char method
2983  *      if present. Returns the number of characters successfully output.
2984  *
2985  *      Note: the specific put_char operation in the driver layer may go
2986  *      away soon. Don't call it directly, use this method
2987  */
2988
2989 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2990 {
2991         if (tty->ops->put_char)
2992                 return tty->ops->put_char(tty, ch);
2993         return tty->ops->write(tty, &ch, 1);
2994 }
2995 EXPORT_SYMBOL_GPL(tty_put_char);
2996
2997 struct class *tty_class;
2998
2999 /**
3000  *      tty_register_device - register a tty device
3001  *      @driver: the tty driver that describes the tty device
3002  *      @index: the index in the tty driver for this tty device
3003  *      @device: a struct device that is associated with this tty device.
3004  *              This field is optional, if there is no known struct device
3005  *              for this tty device it can be set to NULL safely.
3006  *
3007  *      Returns a pointer to the struct device for this tty device
3008  *      (or ERR_PTR(-EFOO) on error).
3009  *
3010  *      This call is required to be made to register an individual tty device
3011  *      if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set.  If
3012  *      that bit is not set, this function should not be called by a tty
3013  *      driver.
3014  *
3015  *      Locking: ??
3016  */
3017
3018 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3019                                    struct device *device)
3020 {
3021         char name[64];
3022         dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
3023
3024         if (index >= driver->num) {
3025                 printk(KERN_ERR "Attempt to register invalid tty line number "
3026                        " (%d).\n", index);
3027                 return ERR_PTR(-EINVAL);
3028         }
3029
3030         if (driver->type == TTY_DRIVER_TYPE_PTY)
3031                 pty_line_name(driver, index, name);
3032         else
3033                 tty_line_name(driver, index, name);
3034
3035         return device_create(tty_class, device, dev, NULL, name);
3036 }
3037 EXPORT_SYMBOL(tty_register_device);
3038
3039 /**
3040  *      tty_unregister_device - unregister a tty device
3041  *      @driver: the tty driver that describes the tty device
3042  *      @index: the index in the tty driver for this tty device
3043  *
3044  *      If a tty device is registered with a call to tty_register_device() then
3045  *      this function must be called when the tty device is gone.
3046  *
3047  *      Locking: ??
3048  */
3049
3050 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3051 {
3052         device_destroy(tty_class,
3053                 MKDEV(driver->major, driver->minor_start) + index);
3054 }
3055 EXPORT_SYMBOL(tty_unregister_device);
3056
3057 struct tty_driver *__alloc_tty_driver(int lines, struct module *owner)
3058 {
3059         struct tty_driver *driver;
3060
3061         driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3062         if (driver) {
3063                 kref_init(&driver->kref);
3064                 driver->magic = TTY_DRIVER_MAGIC;
3065                 driver->num = lines;
3066                 driver->owner = owner;
3067                 /* later we'll move allocation of tables here */
3068         }
3069         return driver;
3070 }
3071 EXPORT_SYMBOL(__alloc_tty_driver);
3072
3073 static void destruct_tty_driver(struct kref *kref)
3074 {
3075         struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3076         int i;
3077         struct ktermios *tp;
3078         void *p;
3079
3080         if (driver->flags & TTY_DRIVER_INSTALLED) {
3081                 /*
3082                  * Free the termios and termios_locked structures because
3083                  * we don't want to get memory leaks when modular tty
3084                  * drivers are removed from the kernel.
3085                  */
3086                 for (i = 0; i < driver->num; i++) {
3087                         tp = driver->termios[i];
3088                         if (tp) {
3089                                 driver->termios[i] = NULL;
3090                                 kfree(tp);
3091                         }
3092                         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3093                                 tty_unregister_device(driver, i);
3094                 }
3095                 p = driver->ttys;
3096                 proc_tty_unregister_driver(driver);
3097                 driver->ttys = NULL;
3098                 driver->termios = NULL;
3099                 kfree(p);
3100                 cdev_del(&driver->cdev);
3101         }
3102         kfree(driver);
3103 }
3104
3105 void tty_driver_kref_put(struct tty_driver *driver)
3106 {
3107         kref_put(&driver->kref, destruct_tty_driver);
3108 }
3109 EXPORT_SYMBOL(tty_driver_kref_put);
3110
3111 void tty_set_operations(struct tty_driver *driver,
3112                         const struct tty_operations *op)
3113 {
3114         driver->ops = op;
3115 };
3116 EXPORT_SYMBOL(tty_set_operations);
3117
3118 void put_tty_driver(struct tty_driver *d)
3119 {
3120         tty_driver_kref_put(d);
3121 }
3122 EXPORT_SYMBOL(put_tty_driver);
3123
3124 /*
3125  * Called by a tty driver to register itself.
3126  */
3127 int tty_register_driver(struct tty_driver *driver)
3128 {
3129         int error;
3130         int i;
3131         dev_t dev;
3132         void **p = NULL;
3133         struct device *d;
3134
3135         if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
3136                 p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
3137                 if (!p)
3138                         return -ENOMEM;
3139         }
3140
3141         if (!driver->major) {
3142                 error = alloc_chrdev_region(&dev, driver->minor_start,
3143                                                 driver->num, driver->name);
3144                 if (!error) {
3145                         driver->major = MAJOR(dev);
3146                         driver->minor_start = MINOR(dev);
3147                 }
3148         } else {
3149                 dev = MKDEV(driver->major, driver->minor_start);
3150                 error = register_chrdev_region(dev, driver->num, driver->name);
3151         }
3152         if (error < 0) {
3153                 kfree(p);
3154                 return error;
3155         }
3156
3157         if (p) {
3158                 driver->ttys = (struct tty_struct **)p;
3159                 driver->termios = (struct ktermios **)(p + driver->num);
3160         } else {
3161                 driver->ttys = NULL;
3162                 driver->termios = NULL;
3163         }
3164
3165         cdev_init(&driver->cdev, &tty_fops);
3166         driver->cdev.owner = driver->owner;
3167         error = cdev_add(&driver->cdev, dev, driver->num);
3168         if (error) {
3169                 unregister_chrdev_region(dev, driver->num);
3170                 driver->ttys = NULL;
3171                 driver->termios = NULL;
3172                 kfree(p);
3173                 return error;
3174         }
3175
3176         mutex_lock(&tty_mutex);
3177         list_add(&driver->tty_drivers, &tty_drivers);
3178         mutex_unlock(&tty_mutex);
3179
3180         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3181                 for (i = 0; i < driver->num; i++) {
3182                         d = tty_register_device(driver, i, NULL);
3183                         if (IS_ERR(d)) {
3184                                 error = PTR_ERR(d);
3185                                 goto err;
3186                         }
3187                 }
3188         }
3189         proc_tty_register_driver(driver);
3190         driver->flags |= TTY_DRIVER_INSTALLED;
3191         return 0;
3192
3193 err:
3194         for (i--; i >= 0; i--)
3195                 tty_unregister_device(driver, i);
3196
3197         mutex_lock(&tty_mutex);
3198         list_del(&driver->tty_drivers);
3199         mutex_unlock(&tty_mutex);
3200
3201         unregister_chrdev_region(dev, driver->num);
3202         driver->ttys = NULL;
3203         driver->termios = NULL;
3204         kfree(p);
3205         return error;
3206 }
3207
3208 EXPORT_SYMBOL(tty_register_driver);
3209
3210 /*
3211  * Called by a tty driver to unregister itself.
3212  */
3213 int tty_unregister_driver(struct tty_driver *driver)
3214 {
3215 #if 0
3216         /* FIXME */
3217         if (driver->refcount)
3218                 return -EBUSY;
3219 #endif
3220         unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3221                                 driver->num);
3222         mutex_lock(&tty_mutex);
3223         list_del(&driver->tty_drivers);
3224         mutex_unlock(&tty_mutex);
3225         return 0;
3226 }
3227
3228 EXPORT_SYMBOL(tty_unregister_driver);
3229
3230 dev_t tty_devnum(struct tty_struct *tty)
3231 {
3232         return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3233 }
3234 EXPORT_SYMBOL(tty_devnum);
3235
3236 void proc_clear_tty(struct task_struct *p)
3237 {
3238         unsigned long flags;
3239         struct tty_struct *tty;
3240         spin_lock_irqsave(&p->sighand->siglock, flags);
3241         tty = p->signal->tty;
3242         p->signal->tty = NULL;
3243         spin_unlock_irqrestore(&p->sighand->siglock, flags);
3244         tty_kref_put(tty);
3245 }
3246
3247 /* Called under the sighand lock */
3248
3249 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3250 {
3251         if (tty) {
3252                 unsigned long flags;
3253                 /* We should not have a session or pgrp to put here but.... */
3254                 spin_lock_irqsave(&tty->ctrl_lock, flags);
3255                 put_pid(tty->session);
3256                 put_pid(tty->pgrp);
3257                 tty->pgrp = get_pid(task_pgrp(tsk));
3258                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3259                 tty->session = get_pid(task_session(tsk));
3260                 if (tsk->signal->tty) {
3261                         printk(KERN_DEBUG "tty not NULL!!\n");
3262                         tty_kref_put(tsk->signal->tty);
3263                 }
3264         }
3265         put_pid(tsk->signal->tty_old_pgrp);
3266         tsk->signal->tty = tty_kref_get(tty);
3267         tsk->signal->tty_old_pgrp = NULL;
3268 }
3269
3270 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3271 {
3272         spin_lock_irq(&tsk->sighand->siglock);
3273         __proc_set_tty(tsk, tty);
3274         spin_unlock_irq(&tsk->sighand->siglock);
3275 }
3276
3277 struct tty_struct *get_current_tty(void)
3278 {
3279         struct tty_struct *tty;
3280         unsigned long flags;
3281
3282         spin_lock_irqsave(&current->sighand->siglock, flags);
3283         tty = tty_kref_get(current->signal->tty);
3284         spin_unlock_irqrestore(&current->sighand->siglock, flags);
3285         return tty;
3286 }
3287 EXPORT_SYMBOL_GPL(get_current_tty);
3288
3289 void tty_default_fops(struct file_operations *fops)
3290 {
3291         *fops = tty_fops;
3292 }
3293
3294 /*
3295  * Initialize the console device. This is called *early*, so
3296  * we can't necessarily depend on lots of kernel help here.
3297  * Just do some early initializations, and do the complex setup
3298  * later.
3299  */
3300 void __init console_init(void)
3301 {
3302         initcall_t *call;
3303
3304         /* Setup the default TTY line discipline. */
3305         tty_ldisc_begin();
3306
3307         /*
3308          * set up the console device so that later boot sequences can
3309          * inform about problems etc..
3310          */
3311         call = __con_initcall_start;
3312         while (call < __con_initcall_end) {
3313                 (*call)();
3314                 call++;
3315         }
3316 }
3317
3318 static char *tty_devnode(struct device *dev, umode_t *mode)
3319 {
3320         if (!mode)
3321                 return NULL;
3322         if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3323             dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3324                 *mode = 0666;
3325         return NULL;
3326 }
3327
3328 static int __init tty_class_init(void)
3329 {
3330         tty_class = class_create(THIS_MODULE, "tty");
3331         if (IS_ERR(tty_class))
3332                 return PTR_ERR(tty_class);
3333         tty_class->devnode = tty_devnode;
3334         return 0;
3335 }
3336
3337 postcore_initcall(tty_class_init);
3338
3339 /* 3/2004 jmc: why do these devices exist? */
3340 static struct cdev tty_cdev, console_cdev;
3341
3342 static ssize_t show_cons_active(struct device *dev,
3343                                 struct device_attribute *attr, char *buf)
3344 {
3345         struct console *cs[16];
3346         int i = 0;
3347         struct console *c;
3348         ssize_t count = 0;
3349
3350         console_lock();
3351         for_each_console(c) {
3352                 if (!c->device)
3353                         continue;
3354                 if (!c->write)
3355                         continue;
3356                 if ((c->flags & CON_ENABLED) == 0)
3357                         continue;
3358                 cs[i++] = c;
3359                 if (i >= ARRAY_SIZE(cs))
3360                         break;
3361         }
3362         while (i--)
3363                 count += sprintf(buf + count, "%s%d%c",
3364                                  cs[i]->name, cs[i]->index, i ? ' ':'\n');
3365         console_unlock();
3366
3367         return count;
3368 }
3369 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3370
3371 static struct device *consdev;
3372
3373 void console_sysfs_notify(void)
3374 {
3375         if (consdev)
3376                 sysfs_notify(&consdev->kobj, NULL, "active");
3377 }
3378
3379 /*
3380  * Ok, now we can initialize the rest of the tty devices and can count
3381  * on memory allocations, interrupts etc..
3382  */
3383 int __init tty_init(void)
3384 {
3385         cdev_init(&tty_cdev, &tty_fops);
3386         if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3387             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3388                 panic("Couldn't register /dev/tty driver\n");
3389         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3390
3391         cdev_init(&console_cdev, &console_fops);
3392         if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3393             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3394                 panic("Couldn't register /dev/console driver\n");
3395         consdev = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3396                               "console");
3397         if (IS_ERR(consdev))
3398                 consdev = NULL;
3399         else
3400                 WARN_ON(device_create_file(consdev, &dev_attr_active) < 0);
3401
3402 #ifdef CONFIG_VT
3403         vty_init(&console_fops);
3404 #endif
3405         return 0;
3406 }
3407