3f48d88cffc046445202cdaece8c346cb272add7
[linux-2.6.git] / drivers / char / tty_io.c
1 /*
2  *  linux/drivers/char/tty_io.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 /*
8  * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
9  * or rs-channels. It also implements echoing, cooked mode etc.
10  *
11  * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
12  *
13  * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
14  * tty_struct and tty_queue structures.  Previously there was an array
15  * of 256 tty_struct's which was statically allocated, and the
16  * tty_queue structures were allocated at boot time.  Both are now
17  * dynamically allocated only when the tty is open.
18  *
19  * Also restructured routines so that there is more of a separation
20  * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
21  * the low-level tty routines (serial.c, pty.c, console.c).  This
22  * makes for cleaner and more compact code.  -TYT, 9/17/92
23  *
24  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
25  * which can be dynamically activated and de-activated by the line
26  * discipline handling modules (like SLIP).
27  *
28  * NOTE: pay no attention to the line discipline code (yet); its
29  * interface is still subject to change in this version...
30  * -- TYT, 1/31/92
31  *
32  * Added functionality to the OPOST tty handling.  No delays, but all
33  * other bits should be there.
34  *      -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
35  *
36  * Rewrote canonical mode and added more termios flags.
37  *      -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
38  *
39  * Reorganized FASYNC support so mouse code can share it.
40  *      -- ctm@ardi.com, 9Sep95
41  *
42  * New TIOCLINUX variants added.
43  *      -- mj@k332.feld.cvut.cz, 19-Nov-95
44  *
45  * Restrict vt switching via ioctl()
46  *      -- grif@cs.ucr.edu, 5-Dec-95
47  *
48  * Move console and virtual terminal code to more appropriate files,
49  * implement CONFIG_VT and generalize console device interface.
50  *      -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
51  *
52  * Rewrote tty_init_dev and tty_release_dev to eliminate races.
53  *      -- Bill Hawes <whawes@star.net>, June 97
54  *
55  * Added devfs support.
56  *      -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
57  *
58  * Added support for a Unix98-style ptmx device.
59  *      -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
60  *
61  * Reduced memory usage for older ARM systems
62  *      -- Russell King <rmk@arm.linux.org.uk>
63  *
64  * Move do_SAK() into process context.  Less stack use in devfs functions.
65  * alloc_tty_struct() always uses kmalloc()
66  *                       -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
67  */
68
69 #include <linux/types.h>
70 #include <linux/major.h>
71 #include <linux/errno.h>
72 #include <linux/signal.h>
73 #include <linux/fcntl.h>
74 #include <linux/sched.h>
75 #include <linux/interrupt.h>
76 #include <linux/tty.h>
77 #include <linux/tty_driver.h>
78 #include <linux/tty_flip.h>
79 #include <linux/devpts_fs.h>
80 #include <linux/file.h>
81 #include <linux/fdtable.h>
82 #include <linux/console.h>
83 #include <linux/timer.h>
84 #include <linux/ctype.h>
85 #include <linux/kd.h>
86 #include <linux/mm.h>
87 #include <linux/string.h>
88 #include <linux/slab.h>
89 #include <linux/poll.h>
90 #include <linux/proc_fs.h>
91 #include <linux/init.h>
92 #include <linux/module.h>
93 #include <linux/smp_lock.h>
94 #include <linux/device.h>
95 #include <linux/wait.h>
96 #include <linux/bitops.h>
97 #include <linux/delay.h>
98 #include <linux/seq_file.h>
99
100 #include <linux/uaccess.h>
101 #include <asm/system.h>
102
103 #include <linux/kbd_kern.h>
104 #include <linux/vt_kern.h>
105 #include <linux/selection.h>
106
107 #include <linux/kmod.h>
108 #include <linux/nsproxy.h>
109
110 #undef TTY_DEBUG_HANGUP
111
112 #define TTY_PARANOIA_CHECK 1
113 #define CHECK_TTY_COUNT 1
114
115 struct ktermios tty_std_termios = {     /* for the benefit of tty drivers  */
116         .c_iflag = ICRNL | IXON,
117         .c_oflag = OPOST | ONLCR,
118         .c_cflag = B38400 | CS8 | CREAD | HUPCL,
119         .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
120                    ECHOCTL | ECHOKE | IEXTEN,
121         .c_cc = INIT_C_CC,
122         .c_ispeed = 38400,
123         .c_ospeed = 38400
124 };
125
126 EXPORT_SYMBOL(tty_std_termios);
127
128 /* This list gets poked at by procfs and various bits of boot up code. This
129    could do with some rationalisation such as pulling the tty proc function
130    into this file */
131
132 LIST_HEAD(tty_drivers);                 /* linked list of tty drivers */
133
134 /* Mutex to protect creating and releasing a tty. This is shared with
135    vt.c for deeply disgusting hack reasons */
136 DEFINE_MUTEX(tty_mutex);
137 EXPORT_SYMBOL(tty_mutex);
138
139 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
140 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
141 ssize_t redirected_tty_write(struct file *, const char __user *,
142                                                         size_t, loff_t *);
143 static unsigned int tty_poll(struct file *, poll_table *);
144 static int tty_open(struct inode *, struct file *);
145 static int tty_release(struct inode *, struct file *);
146 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
147 #ifdef CONFIG_COMPAT
148 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
149                                 unsigned long arg);
150 #else
151 #define tty_compat_ioctl NULL
152 #endif
153 static int tty_fasync(int fd, struct file *filp, int on);
154 static void release_tty(struct tty_struct *tty, int idx);
155 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
156 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
157
158 /**
159  *      alloc_tty_struct        -       allocate a tty object
160  *
161  *      Return a new empty tty structure. The data fields have not
162  *      been initialized in any way but has been zeroed
163  *
164  *      Locking: none
165  */
166
167 struct tty_struct *alloc_tty_struct(void)
168 {
169         return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
170 }
171
172 /**
173  *      free_tty_struct         -       free a disused tty
174  *      @tty: tty struct to free
175  *
176  *      Free the write buffers, tty queue and tty memory itself.
177  *
178  *      Locking: none. Must be called after tty is definitely unused
179  */
180
181 void free_tty_struct(struct tty_struct *tty)
182 {
183         kfree(tty->write_buf);
184         tty_buffer_free_all(tty);
185         kfree(tty);
186 }
187
188 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
189
190 /**
191  *      tty_name        -       return tty naming
192  *      @tty: tty structure
193  *      @buf: buffer for output
194  *
195  *      Convert a tty structure into a name. The name reflects the kernel
196  *      naming policy and if udev is in use may not reflect user space
197  *
198  *      Locking: none
199  */
200
201 char *tty_name(struct tty_struct *tty, char *buf)
202 {
203         if (!tty) /* Hmm.  NULL pointer.  That's fun. */
204                 strcpy(buf, "NULL tty");
205         else
206                 strcpy(buf, tty->name);
207         return buf;
208 }
209
210 EXPORT_SYMBOL(tty_name);
211
212 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
213                               const char *routine)
214 {
215 #ifdef TTY_PARANOIA_CHECK
216         if (!tty) {
217                 printk(KERN_WARNING
218                         "null TTY for (%d:%d) in %s\n",
219                         imajor(inode), iminor(inode), routine);
220                 return 1;
221         }
222         if (tty->magic != TTY_MAGIC) {
223                 printk(KERN_WARNING
224                         "bad magic number for tty struct (%d:%d) in %s\n",
225                         imajor(inode), iminor(inode), routine);
226                 return 1;
227         }
228 #endif
229         return 0;
230 }
231
232 static int check_tty_count(struct tty_struct *tty, const char *routine)
233 {
234 #ifdef CHECK_TTY_COUNT
235         struct list_head *p;
236         int count = 0;
237
238         file_list_lock();
239         list_for_each(p, &tty->tty_files) {
240                 count++;
241         }
242         file_list_unlock();
243         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
244             tty->driver->subtype == PTY_TYPE_SLAVE &&
245             tty->link && tty->link->count)
246                 count++;
247         if (tty->count != count) {
248                 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
249                                     "!= #fd's(%d) in %s\n",
250                        tty->name, tty->count, count, routine);
251                 return count;
252         }
253 #endif
254         return 0;
255 }
256
257 /**
258  *      get_tty_driver          -       find device of a tty
259  *      @dev_t: device identifier
260  *      @index: returns the index of the tty
261  *
262  *      This routine returns a tty driver structure, given a device number
263  *      and also passes back the index number.
264  *
265  *      Locking: caller must hold tty_mutex
266  */
267
268 static struct tty_driver *get_tty_driver(dev_t device, int *index)
269 {
270         struct tty_driver *p;
271
272         list_for_each_entry(p, &tty_drivers, tty_drivers) {
273                 dev_t base = MKDEV(p->major, p->minor_start);
274                 if (device < base || device >= base + p->num)
275                         continue;
276                 *index = device - base;
277                 return tty_driver_kref_get(p);
278         }
279         return NULL;
280 }
281
282 #ifdef CONFIG_CONSOLE_POLL
283
284 /**
285  *      tty_find_polling_driver -       find device of a polled tty
286  *      @name: name string to match
287  *      @line: pointer to resulting tty line nr
288  *
289  *      This routine returns a tty driver structure, given a name
290  *      and the condition that the tty driver is capable of polled
291  *      operation.
292  */
293 struct tty_driver *tty_find_polling_driver(char *name, int *line)
294 {
295         struct tty_driver *p, *res = NULL;
296         int tty_line = 0;
297         int len;
298         char *str;
299
300         for (str = name; *str; str++)
301                 if ((*str >= '0' && *str <= '9') || *str == ',')
302                         break;
303         if (!*str)
304                 return NULL;
305
306         len = str - name;
307         tty_line = simple_strtoul(str, &str, 10);
308
309         mutex_lock(&tty_mutex);
310         /* Search through the tty devices to look for a match */
311         list_for_each_entry(p, &tty_drivers, tty_drivers) {
312                 if (strncmp(name, p->name, len) != 0)
313                         continue;
314                 if (*str == ',')
315                         str++;
316                 if (*str == '\0')
317                         str = NULL;
318
319                 if (tty_line >= 0 && tty_line <= p->num && p->ops &&
320                     p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
321                         res = tty_driver_kref_get(p);
322                         *line = tty_line;
323                         break;
324                 }
325         }
326         mutex_unlock(&tty_mutex);
327
328         return res;
329 }
330 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
331 #endif
332
333 /**
334  *      tty_check_change        -       check for POSIX terminal changes
335  *      @tty: tty to check
336  *
337  *      If we try to write to, or set the state of, a terminal and we're
338  *      not in the foreground, send a SIGTTOU.  If the signal is blocked or
339  *      ignored, go ahead and perform the operation.  (POSIX 7.2)
340  *
341  *      Locking: ctrl_lock
342  */
343
344 int tty_check_change(struct tty_struct *tty)
345 {
346         unsigned long flags;
347         int ret = 0;
348
349         if (current->signal->tty != tty)
350                 return 0;
351
352         spin_lock_irqsave(&tty->ctrl_lock, flags);
353
354         if (!tty->pgrp) {
355                 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
356                 goto out_unlock;
357         }
358         if (task_pgrp(current) == tty->pgrp)
359                 goto out_unlock;
360         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
361         if (is_ignored(SIGTTOU))
362                 goto out;
363         if (is_current_pgrp_orphaned()) {
364                 ret = -EIO;
365                 goto out;
366         }
367         kill_pgrp(task_pgrp(current), SIGTTOU, 1);
368         set_thread_flag(TIF_SIGPENDING);
369         ret = -ERESTARTSYS;
370 out:
371         return ret;
372 out_unlock:
373         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
374         return ret;
375 }
376
377 EXPORT_SYMBOL(tty_check_change);
378
379 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
380                                 size_t count, loff_t *ppos)
381 {
382         return 0;
383 }
384
385 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
386                                  size_t count, loff_t *ppos)
387 {
388         return -EIO;
389 }
390
391 /* No kernel lock held - none needed ;) */
392 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
393 {
394         return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
395 }
396
397 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
398                 unsigned long arg)
399 {
400         return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
401 }
402
403 static long hung_up_tty_compat_ioctl(struct file *file,
404                                      unsigned int cmd, unsigned long arg)
405 {
406         return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
407 }
408
409 static const struct file_operations tty_fops = {
410         .llseek         = no_llseek,
411         .read           = tty_read,
412         .write          = tty_write,
413         .poll           = tty_poll,
414         .unlocked_ioctl = tty_ioctl,
415         .compat_ioctl   = tty_compat_ioctl,
416         .open           = tty_open,
417         .release        = tty_release,
418         .fasync         = tty_fasync,
419 };
420
421 static const struct file_operations console_fops = {
422         .llseek         = no_llseek,
423         .read           = tty_read,
424         .write          = redirected_tty_write,
425         .poll           = tty_poll,
426         .unlocked_ioctl = tty_ioctl,
427         .compat_ioctl   = tty_compat_ioctl,
428         .open           = tty_open,
429         .release        = tty_release,
430         .fasync         = tty_fasync,
431 };
432
433 static const struct file_operations hung_up_tty_fops = {
434         .llseek         = no_llseek,
435         .read           = hung_up_tty_read,
436         .write          = hung_up_tty_write,
437         .poll           = hung_up_tty_poll,
438         .unlocked_ioctl = hung_up_tty_ioctl,
439         .compat_ioctl   = hung_up_tty_compat_ioctl,
440         .release        = tty_release,
441 };
442
443 static DEFINE_SPINLOCK(redirect_lock);
444 static struct file *redirect;
445
446 /**
447  *      tty_wakeup      -       request more data
448  *      @tty: terminal
449  *
450  *      Internal and external helper for wakeups of tty. This function
451  *      informs the line discipline if present that the driver is ready
452  *      to receive more output data.
453  */
454
455 void tty_wakeup(struct tty_struct *tty)
456 {
457         struct tty_ldisc *ld;
458
459         if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
460                 ld = tty_ldisc_ref(tty);
461                 if (ld) {
462                         if (ld->ops->write_wakeup)
463                                 ld->ops->write_wakeup(tty);
464                         tty_ldisc_deref(ld);
465                 }
466         }
467         wake_up_interruptible(&tty->write_wait);
468 }
469
470 EXPORT_SYMBOL_GPL(tty_wakeup);
471
472 /**
473  *      tty_ldisc_flush -       flush line discipline queue
474  *      @tty: tty
475  *
476  *      Flush the line discipline queue (if any) for this tty. If there
477  *      is no line discipline active this is a no-op.
478  */
479
480 void tty_ldisc_flush(struct tty_struct *tty)
481 {
482         struct tty_ldisc *ld = tty_ldisc_ref(tty);
483         if (ld) {
484                 if (ld->ops->flush_buffer)
485                         ld->ops->flush_buffer(tty);
486                 tty_ldisc_deref(ld);
487         }
488         tty_buffer_flush(tty);
489 }
490
491 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
492
493 /**
494  *      tty_reset_termios       -       reset terminal state
495  *      @tty: tty to reset
496  *
497  *      Restore a terminal to the driver default state
498  */
499
500 static void tty_reset_termios(struct tty_struct *tty)
501 {
502         mutex_lock(&tty->termios_mutex);
503         *tty->termios = tty->driver->init_termios;
504         tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
505         tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
506         mutex_unlock(&tty->termios_mutex);
507 }
508
509 /**
510  *      do_tty_hangup           -       actual handler for hangup events
511  *      @work: tty device
512  *
513  *      This can be called by the "eventd" kernel thread.  That is process
514  *      synchronous but doesn't hold any locks, so we need to make sure we
515  *      have the appropriate locks for what we're doing.
516  *
517  *      The hangup event clears any pending redirections onto the hung up
518  *      device. It ensures future writes will error and it does the needed
519  *      line discipline hangup and signal delivery. The tty object itself
520  *      remains intact.
521  *
522  *      Locking:
523  *              BKL
524  *                redirect lock for undoing redirection
525  *                file list lock for manipulating list of ttys
526  *                tty_ldisc_lock from called functions
527  *                termios_mutex resetting termios data
528  *                tasklist_lock to walk task list for hangup event
529  *                  ->siglock to protect ->signal/->sighand
530  */
531 static void do_tty_hangup(struct work_struct *work)
532 {
533         struct tty_struct *tty =
534                 container_of(work, struct tty_struct, hangup_work);
535         struct file *cons_filp = NULL;
536         struct file *filp, *f = NULL;
537         struct task_struct *p;
538         struct tty_ldisc *ld;
539         int    closecount = 0, n;
540         unsigned long flags;
541         int refs = 0;
542
543         if (!tty)
544                 return;
545
546         /* inuse_filps is protected by the single kernel lock */
547         lock_kernel();
548
549         spin_lock(&redirect_lock);
550         if (redirect && redirect->private_data == tty) {
551                 f = redirect;
552                 redirect = NULL;
553         }
554         spin_unlock(&redirect_lock);
555
556         check_tty_count(tty, "do_tty_hangup");
557         file_list_lock();
558         /* This breaks for file handles being sent over AF_UNIX sockets ? */
559         list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
560                 if (filp->f_op->write == redirected_tty_write)
561                         cons_filp = filp;
562                 if (filp->f_op->write != tty_write)
563                         continue;
564                 closecount++;
565                 tty_fasync(-1, filp, 0);        /* can't block */
566                 filp->f_op = &hung_up_tty_fops;
567         }
568         file_list_unlock();
569         /*
570          * FIXME! What are the locking issues here? This may me overdoing
571          * things... This question is especially important now that we've
572          * removed the irqlock.
573          */
574         ld = tty_ldisc_ref(tty);
575         if (ld != NULL) {
576                 /* We may have no line discipline at this point */
577                 if (ld->ops->flush_buffer)
578                         ld->ops->flush_buffer(tty);
579                 tty_driver_flush_buffer(tty);
580                 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
581                     ld->ops->write_wakeup)
582                         ld->ops->write_wakeup(tty);
583                 if (ld->ops->hangup)
584                         ld->ops->hangup(tty);
585         }
586         /*
587          * FIXME: Once we trust the LDISC code better we can wait here for
588          * ldisc completion and fix the driver call race
589          */
590         wake_up_interruptible(&tty->write_wait);
591         wake_up_interruptible(&tty->read_wait);
592         /*
593          * Shutdown the current line discipline, and reset it to
594          * N_TTY.
595          */
596         if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
597                 tty_reset_termios(tty);
598         /* Defer ldisc switch */
599         /* tty_deferred_ldisc_switch(N_TTY);
600
601           This should get done automatically when the port closes and
602           tty_release is called */
603
604         read_lock(&tasklist_lock);
605         if (tty->session) {
606                 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
607                         spin_lock_irq(&p->sighand->siglock);
608                         if (p->signal->tty == tty) {
609                                 p->signal->tty = NULL;
610                                 /* We defer the dereferences outside fo
611                                    the tasklist lock */
612                                 refs++;
613                         }
614                         if (!p->signal->leader) {
615                                 spin_unlock_irq(&p->sighand->siglock);
616                                 continue;
617                         }
618                         __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
619                         __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
620                         put_pid(p->signal->tty_old_pgrp);  /* A noop */
621                         spin_lock_irqsave(&tty->ctrl_lock, flags);
622                         if (tty->pgrp)
623                                 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
624                         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
625                         spin_unlock_irq(&p->sighand->siglock);
626                 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
627         }
628         read_unlock(&tasklist_lock);
629
630         spin_lock_irqsave(&tty->ctrl_lock, flags);
631         tty->flags = 0;
632         put_pid(tty->session);
633         put_pid(tty->pgrp);
634         tty->session = NULL;
635         tty->pgrp = NULL;
636         tty->ctrl_status = 0;
637         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
638
639         /* Account for the p->signal references we killed */
640         while (refs--)
641                 tty_kref_put(tty);
642
643         /*
644          * If one of the devices matches a console pointer, we
645          * cannot just call hangup() because that will cause
646          * tty->count and state->count to go out of sync.
647          * So we just call close() the right number of times.
648          */
649         if (cons_filp) {
650                 if (tty->ops->close)
651                         for (n = 0; n < closecount; n++)
652                                 tty->ops->close(tty, cons_filp);
653         } else if (tty->ops->hangup)
654                 (tty->ops->hangup)(tty);
655         /*
656          * We don't want to have driver/ldisc interactions beyond
657          * the ones we did here. The driver layer expects no
658          * calls after ->hangup() from the ldisc side. However we
659          * can't yet guarantee all that.
660          */
661         set_bit(TTY_HUPPED, &tty->flags);
662         if (ld) {
663                 tty_ldisc_enable(tty);
664                 tty_ldisc_deref(ld);
665         }
666         unlock_kernel();
667         if (f)
668                 fput(f);
669 }
670
671 /**
672  *      tty_hangup              -       trigger a hangup event
673  *      @tty: tty to hangup
674  *
675  *      A carrier loss (virtual or otherwise) has occurred on this like
676  *      schedule a hangup sequence to run after this event.
677  */
678
679 void tty_hangup(struct tty_struct *tty)
680 {
681 #ifdef TTY_DEBUG_HANGUP
682         char    buf[64];
683         printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
684 #endif
685         schedule_work(&tty->hangup_work);
686 }
687
688 EXPORT_SYMBOL(tty_hangup);
689
690 /**
691  *      tty_vhangup             -       process vhangup
692  *      @tty: tty to hangup
693  *
694  *      The user has asked via system call for the terminal to be hung up.
695  *      We do this synchronously so that when the syscall returns the process
696  *      is complete. That guarantee is necessary for security reasons.
697  */
698
699 void tty_vhangup(struct tty_struct *tty)
700 {
701 #ifdef TTY_DEBUG_HANGUP
702         char    buf[64];
703
704         printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
705 #endif
706         do_tty_hangup(&tty->hangup_work);
707 }
708
709 EXPORT_SYMBOL(tty_vhangup);
710
711 /**
712  *      tty_vhangup_self        -       process vhangup for own ctty
713  *
714  *      Perform a vhangup on the current controlling tty
715  */
716
717 void tty_vhangup_self(void)
718 {
719         struct tty_struct *tty;
720
721         tty = get_current_tty();
722         if (tty) {
723                 tty_vhangup(tty);
724                 tty_kref_put(tty);
725         }
726 }
727
728 /**
729  *      tty_hung_up_p           -       was tty hung up
730  *      @filp: file pointer of tty
731  *
732  *      Return true if the tty has been subject to a vhangup or a carrier
733  *      loss
734  */
735
736 int tty_hung_up_p(struct file *filp)
737 {
738         return (filp->f_op == &hung_up_tty_fops);
739 }
740
741 EXPORT_SYMBOL(tty_hung_up_p);
742
743 static void session_clear_tty(struct pid *session)
744 {
745         struct task_struct *p;
746         do_each_pid_task(session, PIDTYPE_SID, p) {
747                 proc_clear_tty(p);
748         } while_each_pid_task(session, PIDTYPE_SID, p);
749 }
750
751 /**
752  *      disassociate_ctty       -       disconnect controlling tty
753  *      @on_exit: true if exiting so need to "hang up" the session
754  *
755  *      This function is typically called only by the session leader, when
756  *      it wants to disassociate itself from its controlling tty.
757  *
758  *      It performs the following functions:
759  *      (1)  Sends a SIGHUP and SIGCONT to the foreground process group
760  *      (2)  Clears the tty from being controlling the session
761  *      (3)  Clears the controlling tty for all processes in the
762  *              session group.
763  *
764  *      The argument on_exit is set to 1 if called when a process is
765  *      exiting; it is 0 if called by the ioctl TIOCNOTTY.
766  *
767  *      Locking:
768  *              BKL is taken for hysterical raisins
769  *                tty_mutex is taken to protect tty
770  *                ->siglock is taken to protect ->signal/->sighand
771  *                tasklist_lock is taken to walk process list for sessions
772  *                  ->siglock is taken to protect ->signal/->sighand
773  */
774
775 void disassociate_ctty(int on_exit)
776 {
777         struct tty_struct *tty;
778         struct pid *tty_pgrp = NULL;
779
780
781         tty = get_current_tty();
782         if (tty) {
783                 tty_pgrp = get_pid(tty->pgrp);
784                 lock_kernel();
785                 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
786                         tty_vhangup(tty);
787                 unlock_kernel();
788                 tty_kref_put(tty);
789         } else if (on_exit) {
790                 struct pid *old_pgrp;
791                 spin_lock_irq(&current->sighand->siglock);
792                 old_pgrp = current->signal->tty_old_pgrp;
793                 current->signal->tty_old_pgrp = NULL;
794                 spin_unlock_irq(&current->sighand->siglock);
795                 if (old_pgrp) {
796                         kill_pgrp(old_pgrp, SIGHUP, on_exit);
797                         kill_pgrp(old_pgrp, SIGCONT, on_exit);
798                         put_pid(old_pgrp);
799                 }
800                 return;
801         }
802         if (tty_pgrp) {
803                 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
804                 if (!on_exit)
805                         kill_pgrp(tty_pgrp, SIGCONT, on_exit);
806                 put_pid(tty_pgrp);
807         }
808
809         spin_lock_irq(&current->sighand->siglock);
810         put_pid(current->signal->tty_old_pgrp);
811         current->signal->tty_old_pgrp = NULL;
812         spin_unlock_irq(&current->sighand->siglock);
813
814         tty = get_current_tty();
815         if (tty) {
816                 unsigned long flags;
817                 spin_lock_irqsave(&tty->ctrl_lock, flags);
818                 put_pid(tty->session);
819                 put_pid(tty->pgrp);
820                 tty->session = NULL;
821                 tty->pgrp = NULL;
822                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
823                 tty_kref_put(tty);
824         } else {
825 #ifdef TTY_DEBUG_HANGUP
826                 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
827                        " = NULL", tty);
828 #endif
829         }
830
831         /* Now clear signal->tty under the lock */
832         read_lock(&tasklist_lock);
833         session_clear_tty(task_session(current));
834         read_unlock(&tasklist_lock);
835 }
836
837 /**
838  *
839  *      no_tty  - Ensure the current process does not have a controlling tty
840  */
841 void no_tty(void)
842 {
843         struct task_struct *tsk = current;
844         lock_kernel();
845         if (tsk->signal->leader)
846                 disassociate_ctty(0);
847         unlock_kernel();
848         proc_clear_tty(tsk);
849 }
850
851
852 /**
853  *      stop_tty        -       propagate flow control
854  *      @tty: tty to stop
855  *
856  *      Perform flow control to the driver. For PTY/TTY pairs we
857  *      must also propagate the TIOCKPKT status. May be called
858  *      on an already stopped device and will not re-call the driver
859  *      method.
860  *
861  *      This functionality is used by both the line disciplines for
862  *      halting incoming flow and by the driver. It may therefore be
863  *      called from any context, may be under the tty atomic_write_lock
864  *      but not always.
865  *
866  *      Locking:
867  *              Uses the tty control lock internally
868  */
869
870 void stop_tty(struct tty_struct *tty)
871 {
872         unsigned long flags;
873         spin_lock_irqsave(&tty->ctrl_lock, flags);
874         if (tty->stopped) {
875                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
876                 return;
877         }
878         tty->stopped = 1;
879         if (tty->link && tty->link->packet) {
880                 tty->ctrl_status &= ~TIOCPKT_START;
881                 tty->ctrl_status |= TIOCPKT_STOP;
882                 wake_up_interruptible(&tty->link->read_wait);
883         }
884         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
885         if (tty->ops->stop)
886                 (tty->ops->stop)(tty);
887 }
888
889 EXPORT_SYMBOL(stop_tty);
890
891 /**
892  *      start_tty       -       propagate flow control
893  *      @tty: tty to start
894  *
895  *      Start a tty that has been stopped if at all possible. Perform
896  *      any necessary wakeups and propagate the TIOCPKT status. If this
897  *      is the tty was previous stopped and is being started then the
898  *      driver start method is invoked and the line discipline woken.
899  *
900  *      Locking:
901  *              ctrl_lock
902  */
903
904 void start_tty(struct tty_struct *tty)
905 {
906         unsigned long flags;
907         spin_lock_irqsave(&tty->ctrl_lock, flags);
908         if (!tty->stopped || tty->flow_stopped) {
909                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
910                 return;
911         }
912         tty->stopped = 0;
913         if (tty->link && tty->link->packet) {
914                 tty->ctrl_status &= ~TIOCPKT_STOP;
915                 tty->ctrl_status |= TIOCPKT_START;
916                 wake_up_interruptible(&tty->link->read_wait);
917         }
918         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
919         if (tty->ops->start)
920                 (tty->ops->start)(tty);
921         /* If we have a running line discipline it may need kicking */
922         tty_wakeup(tty);
923 }
924
925 EXPORT_SYMBOL(start_tty);
926
927 /**
928  *      tty_read        -       read method for tty device files
929  *      @file: pointer to tty file
930  *      @buf: user buffer
931  *      @count: size of user buffer
932  *      @ppos: unused
933  *
934  *      Perform the read system call function on this terminal device. Checks
935  *      for hung up devices before calling the line discipline method.
936  *
937  *      Locking:
938  *              Locks the line discipline internally while needed. Multiple
939  *      read calls may be outstanding in parallel.
940  */
941
942 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
943                         loff_t *ppos)
944 {
945         int i;
946         struct tty_struct *tty;
947         struct inode *inode;
948         struct tty_ldisc *ld;
949
950         tty = (struct tty_struct *)file->private_data;
951         inode = file->f_path.dentry->d_inode;
952         if (tty_paranoia_check(tty, inode, "tty_read"))
953                 return -EIO;
954         if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
955                 return -EIO;
956
957         /* We want to wait for the line discipline to sort out in this
958            situation */
959         ld = tty_ldisc_ref_wait(tty);
960         if (ld->ops->read)
961                 i = (ld->ops->read)(tty, file, buf, count);
962         else
963                 i = -EIO;
964         tty_ldisc_deref(ld);
965         if (i > 0)
966                 inode->i_atime = current_fs_time(inode->i_sb);
967         return i;
968 }
969
970 void tty_write_unlock(struct tty_struct *tty)
971 {
972         mutex_unlock(&tty->atomic_write_lock);
973         wake_up_interruptible(&tty->write_wait);
974 }
975
976 int tty_write_lock(struct tty_struct *tty, int ndelay)
977 {
978         if (!mutex_trylock(&tty->atomic_write_lock)) {
979                 if (ndelay)
980                         return -EAGAIN;
981                 if (mutex_lock_interruptible(&tty->atomic_write_lock))
982                         return -ERESTARTSYS;
983         }
984         return 0;
985 }
986
987 /*
988  * Split writes up in sane blocksizes to avoid
989  * denial-of-service type attacks
990  */
991 static inline ssize_t do_tty_write(
992         ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
993         struct tty_struct *tty,
994         struct file *file,
995         const char __user *buf,
996         size_t count)
997 {
998         ssize_t ret, written = 0;
999         unsigned int chunk;
1000
1001         ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1002         if (ret < 0)
1003                 return ret;
1004
1005         /*
1006          * We chunk up writes into a temporary buffer. This
1007          * simplifies low-level drivers immensely, since they
1008          * don't have locking issues and user mode accesses.
1009          *
1010          * But if TTY_NO_WRITE_SPLIT is set, we should use a
1011          * big chunk-size..
1012          *
1013          * The default chunk-size is 2kB, because the NTTY
1014          * layer has problems with bigger chunks. It will
1015          * claim to be able to handle more characters than
1016          * it actually does.
1017          *
1018          * FIXME: This can probably go away now except that 64K chunks
1019          * are too likely to fail unless switched to vmalloc...
1020          */
1021         chunk = 2048;
1022         if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1023                 chunk = 65536;
1024         if (count < chunk)
1025                 chunk = count;
1026
1027         /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1028         if (tty->write_cnt < chunk) {
1029                 unsigned char *buf_chunk;
1030
1031                 if (chunk < 1024)
1032                         chunk = 1024;
1033
1034                 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1035                 if (!buf_chunk) {
1036                         ret = -ENOMEM;
1037                         goto out;
1038                 }
1039                 kfree(tty->write_buf);
1040                 tty->write_cnt = chunk;
1041                 tty->write_buf = buf_chunk;
1042         }
1043
1044         /* Do the write .. */
1045         for (;;) {
1046                 size_t size = count;
1047                 if (size > chunk)
1048                         size = chunk;
1049                 ret = -EFAULT;
1050                 if (copy_from_user(tty->write_buf, buf, size))
1051                         break;
1052                 ret = write(tty, file, tty->write_buf, size);
1053                 if (ret <= 0)
1054                         break;
1055                 written += ret;
1056                 buf += ret;
1057                 count -= ret;
1058                 if (!count)
1059                         break;
1060                 ret = -ERESTARTSYS;
1061                 if (signal_pending(current))
1062                         break;
1063                 cond_resched();
1064         }
1065         if (written) {
1066                 struct inode *inode = file->f_path.dentry->d_inode;
1067                 inode->i_mtime = current_fs_time(inode->i_sb);
1068                 ret = written;
1069         }
1070 out:
1071         tty_write_unlock(tty);
1072         return ret;
1073 }
1074
1075 /**
1076  * tty_write_message - write a message to a certain tty, not just the console.
1077  * @tty: the destination tty_struct
1078  * @msg: the message to write
1079  *
1080  * This is used for messages that need to be redirected to a specific tty.
1081  * We don't put it into the syslog queue right now maybe in the future if
1082  * really needed.
1083  *
1084  * We must still hold the BKL and test the CLOSING flag for the moment.
1085  */
1086
1087 void tty_write_message(struct tty_struct *tty, char *msg)
1088 {
1089         lock_kernel();
1090         if (tty) {
1091                 mutex_lock(&tty->atomic_write_lock);
1092                 if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags))
1093                         tty->ops->write(tty, msg, strlen(msg));
1094                 tty_write_unlock(tty);
1095         }
1096         unlock_kernel();
1097         return;
1098 }
1099
1100
1101 /**
1102  *      tty_write               -       write method for tty device file
1103  *      @file: tty file pointer
1104  *      @buf: user data to write
1105  *      @count: bytes to write
1106  *      @ppos: unused
1107  *
1108  *      Write data to a tty device via the line discipline.
1109  *
1110  *      Locking:
1111  *              Locks the line discipline as required
1112  *              Writes to the tty driver are serialized by the atomic_write_lock
1113  *      and are then processed in chunks to the device. The line discipline
1114  *      write method will not be involked in parallel for each device
1115  *              The line discipline write method is called under the big
1116  *      kernel lock for historical reasons. New code should not rely on this.
1117  */
1118
1119 static ssize_t tty_write(struct file *file, const char __user *buf,
1120                                                 size_t count, loff_t *ppos)
1121 {
1122         struct tty_struct *tty;
1123         struct inode *inode = file->f_path.dentry->d_inode;
1124         ssize_t ret;
1125         struct tty_ldisc *ld;
1126
1127         tty = (struct tty_struct *)file->private_data;
1128         if (tty_paranoia_check(tty, inode, "tty_write"))
1129                 return -EIO;
1130         if (!tty || !tty->ops->write ||
1131                 (test_bit(TTY_IO_ERROR, &tty->flags)))
1132                         return -EIO;
1133         /* Short term debug to catch buggy drivers */
1134         if (tty->ops->write_room == NULL)
1135                 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1136                         tty->driver->name);
1137         ld = tty_ldisc_ref_wait(tty);
1138         if (!ld->ops->write)
1139                 ret = -EIO;
1140         else
1141                 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1142         tty_ldisc_deref(ld);
1143         return ret;
1144 }
1145
1146 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1147                                                 size_t count, loff_t *ppos)
1148 {
1149         struct file *p = NULL;
1150
1151         spin_lock(&redirect_lock);
1152         if (redirect) {
1153                 get_file(redirect);
1154                 p = redirect;
1155         }
1156         spin_unlock(&redirect_lock);
1157
1158         if (p) {
1159                 ssize_t res;
1160                 res = vfs_write(p, buf, count, &p->f_pos);
1161                 fput(p);
1162                 return res;
1163         }
1164         return tty_write(file, buf, count, ppos);
1165 }
1166
1167 static char ptychar[] = "pqrstuvwxyzabcde";
1168
1169 /**
1170  *      pty_line_name   -       generate name for a pty
1171  *      @driver: the tty driver in use
1172  *      @index: the minor number
1173  *      @p: output buffer of at least 6 bytes
1174  *
1175  *      Generate a name from a driver reference and write it to the output
1176  *      buffer.
1177  *
1178  *      Locking: None
1179  */
1180 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1181 {
1182         int i = index + driver->name_base;
1183         /* ->name is initialized to "ttyp", but "tty" is expected */
1184         sprintf(p, "%s%c%x",
1185                 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1186                 ptychar[i >> 4 & 0xf], i & 0xf);
1187 }
1188
1189 /**
1190  *      tty_line_name   -       generate name for a tty
1191  *      @driver: the tty driver in use
1192  *      @index: the minor number
1193  *      @p: output buffer of at least 7 bytes
1194  *
1195  *      Generate a name from a driver reference and write it to the output
1196  *      buffer.
1197  *
1198  *      Locking: None
1199  */
1200 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1201 {
1202         sprintf(p, "%s%d", driver->name, index + driver->name_base);
1203 }
1204
1205 /**
1206  *      tty_driver_lookup_tty() - find an existing tty, if any
1207  *      @driver: the driver for the tty
1208  *      @idx:    the minor number
1209  *
1210  *      Return the tty, if found or ERR_PTR() otherwise.
1211  *
1212  *      Locking: tty_mutex must be held. If tty is found, the mutex must
1213  *      be held until the 'fast-open' is also done. Will change once we
1214  *      have refcounting in the driver and per driver locking
1215  */
1216 struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1217                 struct inode *inode, int idx)
1218 {
1219         struct tty_struct *tty;
1220
1221         if (driver->ops->lookup)
1222                 return driver->ops->lookup(driver, inode, idx);
1223
1224         tty = driver->ttys[idx];
1225         return tty;
1226 }
1227
1228 /**
1229  *      tty_init_termios        -  helper for termios setup
1230  *      @tty: the tty to set up
1231  *
1232  *      Initialise the termios structures for this tty. Thus runs under
1233  *      the tty_mutex currently so we can be relaxed about ordering.
1234  */
1235
1236 int tty_init_termios(struct tty_struct *tty)
1237 {
1238         struct ktermios *tp;
1239         int idx = tty->index;
1240
1241         tp = tty->driver->termios[idx];
1242         if (tp == NULL) {
1243                 tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
1244                 if (tp == NULL)
1245                         return -ENOMEM;
1246                 memcpy(tp, &tty->driver->init_termios,
1247                                                 sizeof(struct ktermios));
1248                 tty->driver->termios[idx] = tp;
1249         }
1250         tty->termios = tp;
1251         tty->termios_locked = tp + 1;
1252
1253         /* Compatibility until drivers always set this */
1254         tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1255         tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1256         return 0;
1257 }
1258
1259 /**
1260  *      tty_driver_install_tty() - install a tty entry in the driver
1261  *      @driver: the driver for the tty
1262  *      @tty: the tty
1263  *
1264  *      Install a tty object into the driver tables. The tty->index field
1265  *      will be set by the time this is called. This method is responsible
1266  *      for ensuring any need additional structures are allocated and
1267  *      configured.
1268  *
1269  *      Locking: tty_mutex for now
1270  */
1271 static int tty_driver_install_tty(struct tty_driver *driver,
1272                                                 struct tty_struct *tty)
1273 {
1274         int idx = tty->index;
1275
1276         if (driver->ops->install)
1277                 return driver->ops->install(driver, tty);
1278
1279         if (tty_init_termios(tty) == 0) {
1280                 tty_driver_kref_get(driver);
1281                 tty->count++;
1282                 driver->ttys[idx] = tty;
1283                 return 0;
1284         }
1285         return -ENOMEM;
1286 }
1287
1288 /**
1289  *      tty_driver_remove_tty() - remove a tty from the driver tables
1290  *      @driver: the driver for the tty
1291  *      @idx:    the minor number
1292  *
1293  *      Remvoe a tty object from the driver tables. The tty->index field
1294  *      will be set by the time this is called.
1295  *
1296  *      Locking: tty_mutex for now
1297  */
1298 static void tty_driver_remove_tty(struct tty_driver *driver,
1299                                                 struct tty_struct *tty)
1300 {
1301         if (driver->ops->remove)
1302                 driver->ops->remove(driver, tty);
1303         else
1304                 driver->ttys[tty->index] = NULL;
1305 }
1306
1307 /*
1308  *      tty_reopen()    - fast re-open of an open tty
1309  *      @tty    - the tty to open
1310  *
1311  *      Return 0 on success, -errno on error.
1312  *
1313  *      Locking: tty_mutex must be held from the time the tty was found
1314  *               till this open completes.
1315  */
1316 static int tty_reopen(struct tty_struct *tty)
1317 {
1318         struct tty_driver *driver = tty->driver;
1319
1320         if (test_bit(TTY_CLOSING, &tty->flags))
1321                 return -EIO;
1322
1323         if (driver->type == TTY_DRIVER_TYPE_PTY &&
1324             driver->subtype == PTY_TYPE_MASTER) {
1325                 /*
1326                  * special case for PTY masters: only one open permitted,
1327                  * and the slave side open count is incremented as well.
1328                  */
1329                 if (tty->count)
1330                         return -EIO;
1331
1332                 tty->link->count++;
1333         }
1334         tty->count++;
1335         tty->driver = driver; /* N.B. why do this every time?? */
1336
1337         WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1338
1339         return 0;
1340 }
1341
1342 /**
1343  *      tty_init_dev            -       initialise a tty device
1344  *      @driver: tty driver we are opening a device on
1345  *      @idx: device index
1346  *      @ret_tty: returned tty structure
1347  *      @first_ok: ok to open a new device (used by ptmx)
1348  *
1349  *      Prepare a tty device. This may not be a "new" clean device but
1350  *      could also be an active device. The pty drivers require special
1351  *      handling because of this.
1352  *
1353  *      Locking:
1354  *              The function is called under the tty_mutex, which
1355  *      protects us from the tty struct or driver itself going away.
1356  *
1357  *      On exit the tty device has the line discipline attached and
1358  *      a reference count of 1. If a pair was created for pty/tty use
1359  *      and the other was a pty master then it too has a reference count of 1.
1360  *
1361  * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1362  * failed open.  The new code protects the open with a mutex, so it's
1363  * really quite straightforward.  The mutex locking can probably be
1364  * relaxed for the (most common) case of reopening a tty.
1365  */
1366
1367 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
1368                                                                 int first_ok)
1369 {
1370         struct tty_struct *tty;
1371         int retval;
1372
1373         /* Check if pty master is being opened multiple times */
1374         if (driver->subtype == PTY_TYPE_MASTER &&
1375                 (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok)
1376                 return ERR_PTR(-EIO);
1377
1378         /*
1379          * First time open is complex, especially for PTY devices.
1380          * This code guarantees that either everything succeeds and the
1381          * TTY is ready for operation, or else the table slots are vacated
1382          * and the allocated memory released.  (Except that the termios
1383          * and locked termios may be retained.)
1384          */
1385
1386         if (!try_module_get(driver->owner))
1387                 return ERR_PTR(-ENODEV);
1388
1389         tty = alloc_tty_struct();
1390         if (!tty)
1391                 goto fail_no_mem;
1392         initialize_tty_struct(tty, driver, idx);
1393
1394         retval = tty_driver_install_tty(driver, tty);
1395         if (retval < 0) {
1396                 free_tty_struct(tty);
1397                 module_put(driver->owner);
1398                 return ERR_PTR(retval);
1399         }
1400
1401         /*
1402          * Structures all installed ... call the ldisc open routines.
1403          * If we fail here just call release_tty to clean up.  No need
1404          * to decrement the use counts, as release_tty doesn't care.
1405          */
1406
1407         retval = tty_ldisc_setup(tty, tty->link);
1408         if (retval)
1409                 goto release_mem_out;
1410         return tty;
1411
1412 fail_no_mem:
1413         module_put(driver->owner);
1414         return ERR_PTR(-ENOMEM);
1415
1416         /* call the tty release_tty routine to clean out this slot */
1417 release_mem_out:
1418         if (printk_ratelimit())
1419                 printk(KERN_INFO "tty_init_dev: ldisc open failed, "
1420                                  "clearing slot %d\n", idx);
1421         release_tty(tty, idx);
1422         return ERR_PTR(retval);
1423 }
1424
1425 void tty_free_termios(struct tty_struct *tty)
1426 {
1427         struct ktermios *tp;
1428         int idx = tty->index;
1429         /* Kill this flag and push into drivers for locking etc */
1430         if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
1431                 /* FIXME: Locking on ->termios array */
1432                 tp = tty->termios;
1433                 tty->driver->termios[idx] = NULL;
1434                 kfree(tp);
1435         }
1436 }
1437 EXPORT_SYMBOL(tty_free_termios);
1438
1439 void tty_shutdown(struct tty_struct *tty)
1440 {
1441         tty_driver_remove_tty(tty->driver, tty);
1442         tty_free_termios(tty);
1443 }
1444 EXPORT_SYMBOL(tty_shutdown);
1445
1446 /**
1447  *      release_one_tty         -       release tty structure memory
1448  *      @kref: kref of tty we are obliterating
1449  *
1450  *      Releases memory associated with a tty structure, and clears out the
1451  *      driver table slots. This function is called when a device is no longer
1452  *      in use. It also gets called when setup of a device fails.
1453  *
1454  *      Locking:
1455  *              tty_mutex - sometimes only
1456  *              takes the file list lock internally when working on the list
1457  *      of ttys that the driver keeps.
1458  */
1459 static void release_one_tty(struct kref *kref)
1460 {
1461         struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1462         struct tty_driver *driver = tty->driver;
1463
1464         if (tty->ops->shutdown)
1465                 tty->ops->shutdown(tty);
1466         else
1467                 tty_shutdown(tty);
1468         tty->magic = 0;
1469         tty_driver_kref_put(driver);
1470         module_put(driver->owner);
1471
1472         file_list_lock();
1473         list_del_init(&tty->tty_files);
1474         file_list_unlock();
1475
1476         free_tty_struct(tty);
1477 }
1478
1479 /**
1480  *      tty_kref_put            -       release a tty kref
1481  *      @tty: tty device
1482  *
1483  *      Release a reference to a tty device and if need be let the kref
1484  *      layer destruct the object for us
1485  */
1486
1487 void tty_kref_put(struct tty_struct *tty)
1488 {
1489         if (tty)
1490                 kref_put(&tty->kref, release_one_tty);
1491 }
1492 EXPORT_SYMBOL(tty_kref_put);
1493
1494 /**
1495  *      release_tty             -       release tty structure memory
1496  *
1497  *      Release both @tty and a possible linked partner (think pty pair),
1498  *      and decrement the refcount of the backing module.
1499  *
1500  *      Locking:
1501  *              tty_mutex - sometimes only
1502  *              takes the file list lock internally when working on the list
1503  *      of ttys that the driver keeps.
1504  *              FIXME: should we require tty_mutex is held here ??
1505  *
1506  */
1507 static void release_tty(struct tty_struct *tty, int idx)
1508 {
1509         /* This should always be true but check for the moment */
1510         WARN_ON(tty->index != idx);
1511
1512         if (tty->link)
1513                 tty_kref_put(tty->link);
1514         tty_kref_put(tty);
1515 }
1516
1517 /*
1518  * Even releasing the tty structures is a tricky business.. We have
1519  * to be very careful that the structures are all released at the
1520  * same time, as interrupts might otherwise get the wrong pointers.
1521  *
1522  * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1523  * lead to double frees or releasing memory still in use.
1524  */
1525 void tty_release_dev(struct file *filp)
1526 {
1527         struct tty_struct *tty, *o_tty;
1528         int     pty_master, tty_closing, o_tty_closing, do_sleep;
1529         int     devpts;
1530         int     idx;
1531         char    buf[64];
1532         struct  inode *inode;
1533
1534         inode = filp->f_path.dentry->d_inode;
1535         tty = (struct tty_struct *)filp->private_data;
1536         if (tty_paranoia_check(tty, inode, "tty_release_dev"))
1537                 return;
1538
1539         check_tty_count(tty, "tty_release_dev");
1540
1541         tty_fasync(-1, filp, 0);
1542
1543         idx = tty->index;
1544         pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1545                       tty->driver->subtype == PTY_TYPE_MASTER);
1546         devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1547         o_tty = tty->link;
1548
1549 #ifdef TTY_PARANOIA_CHECK
1550         if (idx < 0 || idx >= tty->driver->num) {
1551                 printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
1552                                   "free (%s)\n", tty->name);
1553                 return;
1554         }
1555         if (!devpts) {
1556                 if (tty != tty->driver->ttys[idx]) {
1557                         printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
1558                                "for (%s)\n", idx, tty->name);
1559                         return;
1560                 }
1561                 if (tty->termios != tty->driver->termios[idx]) {
1562                         printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
1563                                "for (%s)\n",
1564                                idx, tty->name);
1565                         return;
1566                 }
1567         }
1568 #endif
1569
1570 #ifdef TTY_DEBUG_HANGUP
1571         printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
1572                tty_name(tty, buf), tty->count);
1573 #endif
1574
1575 #ifdef TTY_PARANOIA_CHECK
1576         if (tty->driver->other &&
1577              !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
1578                 if (o_tty != tty->driver->other->ttys[idx]) {
1579                         printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
1580                                           "not o_tty for (%s)\n",
1581                                idx, tty->name);
1582                         return;
1583                 }
1584                 if (o_tty->termios != tty->driver->other->termios[idx]) {
1585                         printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
1586                                           "not o_termios for (%s)\n",
1587                                idx, tty->name);
1588                         return;
1589                 }
1590                 if (o_tty->link != tty) {
1591                         printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
1592                         return;
1593                 }
1594         }
1595 #endif
1596         if (tty->ops->close)
1597                 tty->ops->close(tty, filp);
1598
1599         /*
1600          * Sanity check: if tty->count is going to zero, there shouldn't be
1601          * any waiters on tty->read_wait or tty->write_wait.  We test the
1602          * wait queues and kick everyone out _before_ actually starting to
1603          * close.  This ensures that we won't block while releasing the tty
1604          * structure.
1605          *
1606          * The test for the o_tty closing is necessary, since the master and
1607          * slave sides may close in any order.  If the slave side closes out
1608          * first, its count will be one, since the master side holds an open.
1609          * Thus this test wouldn't be triggered at the time the slave closes,
1610          * so we do it now.
1611          *
1612          * Note that it's possible for the tty to be opened again while we're
1613          * flushing out waiters.  By recalculating the closing flags before
1614          * each iteration we avoid any problems.
1615          */
1616         while (1) {
1617                 /* Guard against races with tty->count changes elsewhere and
1618                    opens on /dev/tty */
1619
1620                 mutex_lock(&tty_mutex);
1621                 tty_closing = tty->count <= 1;
1622                 o_tty_closing = o_tty &&
1623                         (o_tty->count <= (pty_master ? 1 : 0));
1624                 do_sleep = 0;
1625
1626                 if (tty_closing) {
1627                         if (waitqueue_active(&tty->read_wait)) {
1628                                 wake_up(&tty->read_wait);
1629                                 do_sleep++;
1630                         }
1631                         if (waitqueue_active(&tty->write_wait)) {
1632                                 wake_up(&tty->write_wait);
1633                                 do_sleep++;
1634                         }
1635                 }
1636                 if (o_tty_closing) {
1637                         if (waitqueue_active(&o_tty->read_wait)) {
1638                                 wake_up(&o_tty->read_wait);
1639                                 do_sleep++;
1640                         }
1641                         if (waitqueue_active(&o_tty->write_wait)) {
1642                                 wake_up(&o_tty->write_wait);
1643                                 do_sleep++;
1644                         }
1645                 }
1646                 if (!do_sleep)
1647                         break;
1648
1649                 printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
1650                                     "active!\n", tty_name(tty, buf));
1651                 mutex_unlock(&tty_mutex);
1652                 schedule();
1653         }
1654
1655         /*
1656          * The closing flags are now consistent with the open counts on
1657          * both sides, and we've completed the last operation that could
1658          * block, so it's safe to proceed with closing.
1659          */
1660         if (pty_master) {
1661                 if (--o_tty->count < 0) {
1662                         printk(KERN_WARNING "tty_release_dev: bad pty slave count "
1663                                             "(%d) for %s\n",
1664                                o_tty->count, tty_name(o_tty, buf));
1665                         o_tty->count = 0;
1666                 }
1667         }
1668         if (--tty->count < 0) {
1669                 printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
1670                        tty->count, tty_name(tty, buf));
1671                 tty->count = 0;
1672         }
1673
1674         /*
1675          * We've decremented tty->count, so we need to remove this file
1676          * descriptor off the tty->tty_files list; this serves two
1677          * purposes:
1678          *  - check_tty_count sees the correct number of file descriptors
1679          *    associated with this tty.
1680          *  - do_tty_hangup no longer sees this file descriptor as
1681          *    something that needs to be handled for hangups.
1682          */
1683         file_kill(filp);
1684         filp->private_data = NULL;
1685
1686         /*
1687          * Perform some housekeeping before deciding whether to return.
1688          *
1689          * Set the TTY_CLOSING flag if this was the last open.  In the
1690          * case of a pty we may have to wait around for the other side
1691          * to close, and TTY_CLOSING makes sure we can't be reopened.
1692          */
1693         if (tty_closing)
1694                 set_bit(TTY_CLOSING, &tty->flags);
1695         if (o_tty_closing)
1696                 set_bit(TTY_CLOSING, &o_tty->flags);
1697
1698         /*
1699          * If _either_ side is closing, make sure there aren't any
1700          * processes that still think tty or o_tty is their controlling
1701          * tty.
1702          */
1703         if (tty_closing || o_tty_closing) {
1704                 read_lock(&tasklist_lock);
1705                 session_clear_tty(tty->session);
1706                 if (o_tty)
1707                         session_clear_tty(o_tty->session);
1708                 read_unlock(&tasklist_lock);
1709         }
1710
1711         mutex_unlock(&tty_mutex);
1712
1713         /* check whether both sides are closing ... */
1714         if (!tty_closing || (o_tty && !o_tty_closing))
1715                 return;
1716
1717 #ifdef TTY_DEBUG_HANGUP
1718         printk(KERN_DEBUG "freeing tty structure...");
1719 #endif
1720         /*
1721          * Ask the line discipline code to release its structures
1722          */
1723         tty_ldisc_release(tty, o_tty);
1724         /*
1725          * The release_tty function takes care of the details of clearing
1726          * the slots and preserving the termios structure.
1727          */
1728         release_tty(tty, idx);
1729
1730         /* Make this pty number available for reallocation */
1731         if (devpts)
1732                 devpts_kill_index(inode, idx);
1733 }
1734
1735 /**
1736  *      __tty_open              -       open a tty device
1737  *      @inode: inode of device file
1738  *      @filp: file pointer to tty
1739  *
1740  *      tty_open and tty_release keep up the tty count that contains the
1741  *      number of opens done on a tty. We cannot use the inode-count, as
1742  *      different inodes might point to the same tty.
1743  *
1744  *      Open-counting is needed for pty masters, as well as for keeping
1745  *      track of serial lines: DTR is dropped when the last close happens.
1746  *      (This is not done solely through tty->count, now.  - Ted 1/27/92)
1747  *
1748  *      The termios state of a pty is reset on first open so that
1749  *      settings don't persist across reuse.
1750  *
1751  *      Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
1752  *               tty->count should protect the rest.
1753  *               ->siglock protects ->signal/->sighand
1754  */
1755
1756 static int __tty_open(struct inode *inode, struct file *filp)
1757 {
1758         struct tty_struct *tty = NULL;
1759         int noctty, retval;
1760         struct tty_driver *driver;
1761         int index;
1762         dev_t device = inode->i_rdev;
1763         unsigned short saved_flags = filp->f_flags;
1764
1765         nonseekable_open(inode, filp);
1766
1767 retry_open:
1768         noctty = filp->f_flags & O_NOCTTY;
1769         index  = -1;
1770         retval = 0;
1771
1772         mutex_lock(&tty_mutex);
1773
1774         if (device == MKDEV(TTYAUX_MAJOR, 0)) {
1775                 tty = get_current_tty();
1776                 if (!tty) {
1777                         mutex_unlock(&tty_mutex);
1778                         return -ENXIO;
1779                 }
1780                 driver = tty_driver_kref_get(tty->driver);
1781                 index = tty->index;
1782                 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1783                 /* noctty = 1; */
1784                 /* FIXME: Should we take a driver reference ? */
1785                 tty_kref_put(tty);
1786                 goto got_driver;
1787         }
1788 #ifdef CONFIG_VT
1789         if (device == MKDEV(TTY_MAJOR, 0)) {
1790                 extern struct tty_driver *console_driver;
1791                 driver = tty_driver_kref_get(console_driver);
1792                 index = fg_console;
1793                 noctty = 1;
1794                 goto got_driver;
1795         }
1796 #endif
1797         if (device == MKDEV(TTYAUX_MAJOR, 1)) {
1798                 driver = tty_driver_kref_get(console_device(&index));
1799                 if (driver) {
1800                         /* Don't let /dev/console block */
1801                         filp->f_flags |= O_NONBLOCK;
1802                         noctty = 1;
1803                         goto got_driver;
1804                 }
1805                 mutex_unlock(&tty_mutex);
1806                 return -ENODEV;
1807         }
1808
1809         driver = get_tty_driver(device, &index);
1810         if (!driver) {
1811                 mutex_unlock(&tty_mutex);
1812                 return -ENODEV;
1813         }
1814 got_driver:
1815         if (!tty) {
1816                 /* check whether we're reopening an existing tty */
1817                 tty = tty_driver_lookup_tty(driver, inode, index);
1818
1819                 if (IS_ERR(tty))
1820                         return PTR_ERR(tty);
1821         }
1822
1823         if (tty) {
1824                 retval = tty_reopen(tty);
1825                 if (retval)
1826                         tty = ERR_PTR(retval);
1827         } else
1828                 tty = tty_init_dev(driver, index, 0);
1829
1830         mutex_unlock(&tty_mutex);
1831         tty_driver_kref_put(driver);
1832         if (IS_ERR(tty))
1833                 return PTR_ERR(tty);
1834
1835         filp->private_data = tty;
1836         file_move(filp, &tty->tty_files);
1837         check_tty_count(tty, "tty_open");
1838         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1839             tty->driver->subtype == PTY_TYPE_MASTER)
1840                 noctty = 1;
1841 #ifdef TTY_DEBUG_HANGUP
1842         printk(KERN_DEBUG "opening %s...", tty->name);
1843 #endif
1844         if (!retval) {
1845                 if (tty->ops->open)
1846                         retval = tty->ops->open(tty, filp);
1847                 else
1848                         retval = -ENODEV;
1849         }
1850         filp->f_flags = saved_flags;
1851
1852         if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
1853                                                 !capable(CAP_SYS_ADMIN))
1854                 retval = -EBUSY;
1855
1856         if (retval) {
1857 #ifdef TTY_DEBUG_HANGUP
1858                 printk(KERN_DEBUG "error %d in opening %s...", retval,
1859                        tty->name);
1860 #endif
1861                 tty_release_dev(filp);
1862                 if (retval != -ERESTARTSYS)
1863                         return retval;
1864                 if (signal_pending(current))
1865                         return retval;
1866                 schedule();
1867                 /*
1868                  * Need to reset f_op in case a hangup happened.
1869                  */
1870                 if (filp->f_op == &hung_up_tty_fops)
1871                         filp->f_op = &tty_fops;
1872                 goto retry_open;
1873         }
1874
1875         mutex_lock(&tty_mutex);
1876         spin_lock_irq(&current->sighand->siglock);
1877         if (!noctty &&
1878             current->signal->leader &&
1879             !current->signal->tty &&
1880             tty->session == NULL)
1881                 __proc_set_tty(current, tty);
1882         spin_unlock_irq(&current->sighand->siglock);
1883         mutex_unlock(&tty_mutex);
1884         return 0;
1885 }
1886
1887 /* BKL pushdown: scary code avoidance wrapper */
1888 static int tty_open(struct inode *inode, struct file *filp)
1889 {
1890         int ret;
1891
1892         lock_kernel();
1893         ret = __tty_open(inode, filp);
1894         unlock_kernel();
1895         return ret;
1896 }
1897
1898
1899
1900
1901 /**
1902  *      tty_release             -       vfs callback for close
1903  *      @inode: inode of tty
1904  *      @filp: file pointer for handle to tty
1905  *
1906  *      Called the last time each file handle is closed that references
1907  *      this tty. There may however be several such references.
1908  *
1909  *      Locking:
1910  *              Takes bkl. See tty_release_dev
1911  */
1912
1913 static int tty_release(struct inode *inode, struct file *filp)
1914 {
1915         lock_kernel();
1916         tty_release_dev(filp);
1917         unlock_kernel();
1918         return 0;
1919 }
1920
1921 /**
1922  *      tty_poll        -       check tty status
1923  *      @filp: file being polled
1924  *      @wait: poll wait structures to update
1925  *
1926  *      Call the line discipline polling method to obtain the poll
1927  *      status of the device.
1928  *
1929  *      Locking: locks called line discipline but ldisc poll method
1930  *      may be re-entered freely by other callers.
1931  */
1932
1933 static unsigned int tty_poll(struct file *filp, poll_table *wait)
1934 {
1935         struct tty_struct *tty;
1936         struct tty_ldisc *ld;
1937         int ret = 0;
1938
1939         tty = (struct tty_struct *)filp->private_data;
1940         if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
1941                 return 0;
1942
1943         ld = tty_ldisc_ref_wait(tty);
1944         if (ld->ops->poll)
1945                 ret = (ld->ops->poll)(tty, filp, wait);
1946         tty_ldisc_deref(ld);
1947         return ret;
1948 }
1949
1950 static int tty_fasync(int fd, struct file *filp, int on)
1951 {
1952         struct tty_struct *tty;
1953         unsigned long flags;
1954         int retval = 0;
1955
1956         lock_kernel();
1957         tty = (struct tty_struct *)filp->private_data;
1958         if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
1959                 goto out;
1960
1961         retval = fasync_helper(fd, filp, on, &tty->fasync);
1962         if (retval <= 0)
1963                 goto out;
1964
1965         if (on) {
1966                 enum pid_type type;
1967                 struct pid *pid;
1968                 if (!waitqueue_active(&tty->read_wait))
1969                         tty->minimum_to_wake = 1;
1970                 spin_lock_irqsave(&tty->ctrl_lock, flags);
1971                 if (tty->pgrp) {
1972                         pid = tty->pgrp;
1973                         type = PIDTYPE_PGID;
1974                 } else {
1975                         pid = task_pid(current);
1976                         type = PIDTYPE_PID;
1977                 }
1978                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1979                 retval = __f_setown(filp, pid, type, 0);
1980                 if (retval)
1981                         goto out;
1982         } else {
1983                 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
1984                         tty->minimum_to_wake = N_TTY_BUF_SIZE;
1985         }
1986         retval = 0;
1987 out:
1988         unlock_kernel();
1989         return retval;
1990 }
1991
1992 /**
1993  *      tiocsti                 -       fake input character
1994  *      @tty: tty to fake input into
1995  *      @p: pointer to character
1996  *
1997  *      Fake input to a tty device. Does the necessary locking and
1998  *      input management.
1999  *
2000  *      FIXME: does not honour flow control ??
2001  *
2002  *      Locking:
2003  *              Called functions take tty_ldisc_lock
2004  *              current->signal->tty check is safe without locks
2005  *
2006  *      FIXME: may race normal receive processing
2007  */
2008
2009 static int tiocsti(struct tty_struct *tty, char __user *p)
2010 {
2011         char ch, mbz = 0;
2012         struct tty_ldisc *ld;
2013
2014         if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2015                 return -EPERM;
2016         if (get_user(ch, p))
2017                 return -EFAULT;
2018         ld = tty_ldisc_ref_wait(tty);
2019         ld->ops->receive_buf(tty, &ch, &mbz, 1);
2020         tty_ldisc_deref(ld);
2021         return 0;
2022 }
2023
2024 /**
2025  *      tiocgwinsz              -       implement window query ioctl
2026  *      @tty; tty
2027  *      @arg: user buffer for result
2028  *
2029  *      Copies the kernel idea of the window size into the user buffer.
2030  *
2031  *      Locking: tty->termios_mutex is taken to ensure the winsize data
2032  *              is consistent.
2033  */
2034
2035 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2036 {
2037         int err;
2038
2039         mutex_lock(&tty->termios_mutex);
2040         err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2041         mutex_unlock(&tty->termios_mutex);
2042
2043         return err ? -EFAULT: 0;
2044 }
2045
2046 /**
2047  *      tty_do_resize           -       resize event
2048  *      @tty: tty being resized
2049  *      @real_tty: real tty (not the same as tty if using a pty/tty pair)
2050  *      @rows: rows (character)
2051  *      @cols: cols (character)
2052  *
2053  *      Update the termios variables and send the neccessary signals to
2054  *      peform a terminal resize correctly
2055  */
2056
2057 int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
2058                                         struct winsize *ws)
2059 {
2060         struct pid *pgrp, *rpgrp;
2061         unsigned long flags;
2062
2063         /* For a PTY we need to lock the tty side */
2064         mutex_lock(&real_tty->termios_mutex);
2065         if (!memcmp(ws, &real_tty->winsize, sizeof(*ws)))
2066                 goto done;
2067         /* Get the PID values and reference them so we can
2068            avoid holding the tty ctrl lock while sending signals */
2069         spin_lock_irqsave(&tty->ctrl_lock, flags);
2070         pgrp = get_pid(tty->pgrp);
2071         rpgrp = get_pid(real_tty->pgrp);
2072         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2073
2074         if (pgrp)
2075                 kill_pgrp(pgrp, SIGWINCH, 1);
2076         if (rpgrp != pgrp && rpgrp)
2077                 kill_pgrp(rpgrp, SIGWINCH, 1);
2078
2079         put_pid(pgrp);
2080         put_pid(rpgrp);
2081
2082         tty->winsize = *ws;
2083         real_tty->winsize = *ws;
2084 done:
2085         mutex_unlock(&real_tty->termios_mutex);
2086         return 0;
2087 }
2088
2089 /**
2090  *      tiocswinsz              -       implement window size set ioctl
2091  *      @tty; tty
2092  *      @arg: user buffer for result
2093  *
2094  *      Copies the user idea of the window size to the kernel. Traditionally
2095  *      this is just advisory information but for the Linux console it
2096  *      actually has driver level meaning and triggers a VC resize.
2097  *
2098  *      Locking:
2099  *              Driver dependant. The default do_resize method takes the
2100  *      tty termios mutex and ctrl_lock. The console takes its own lock
2101  *      then calls into the default method.
2102  */
2103
2104 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
2105         struct winsize __user *arg)
2106 {
2107         struct winsize tmp_ws;
2108         if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2109                 return -EFAULT;
2110
2111         if (tty->ops->resize)
2112                 return tty->ops->resize(tty, real_tty, &tmp_ws);
2113         else
2114                 return tty_do_resize(tty, real_tty, &tmp_ws);
2115 }
2116
2117 /**
2118  *      tioccons        -       allow admin to move logical console
2119  *      @file: the file to become console
2120  *
2121  *      Allow the adminstrator to move the redirected console device
2122  *
2123  *      Locking: uses redirect_lock to guard the redirect information
2124  */
2125
2126 static int tioccons(struct file *file)
2127 {
2128         if (!capable(CAP_SYS_ADMIN))
2129                 return -EPERM;
2130         if (file->f_op->write == redirected_tty_write) {
2131                 struct file *f;
2132                 spin_lock(&redirect_lock);
2133                 f = redirect;
2134                 redirect = NULL;
2135                 spin_unlock(&redirect_lock);
2136                 if (f)
2137                         fput(f);
2138                 return 0;
2139         }
2140         spin_lock(&redirect_lock);
2141         if (redirect) {
2142                 spin_unlock(&redirect_lock);
2143                 return -EBUSY;
2144         }
2145         get_file(file);
2146         redirect = file;
2147         spin_unlock(&redirect_lock);
2148         return 0;
2149 }
2150
2151 /**
2152  *      fionbio         -       non blocking ioctl
2153  *      @file: file to set blocking value
2154  *      @p: user parameter
2155  *
2156  *      Historical tty interfaces had a blocking control ioctl before
2157  *      the generic functionality existed. This piece of history is preserved
2158  *      in the expected tty API of posix OS's.
2159  *
2160  *      Locking: none, the open fle handle ensures it won't go away.
2161  */
2162
2163 static int fionbio(struct file *file, int __user *p)
2164 {
2165         int nonblock;
2166
2167         if (get_user(nonblock, p))
2168                 return -EFAULT;
2169
2170         /* file->f_flags is still BKL protected in the fs layer - vomit */
2171         lock_kernel();
2172         if (nonblock)
2173                 file->f_flags |= O_NONBLOCK;
2174         else
2175                 file->f_flags &= ~O_NONBLOCK;
2176         unlock_kernel();
2177         return 0;
2178 }
2179
2180 /**
2181  *      tiocsctty       -       set controlling tty
2182  *      @tty: tty structure
2183  *      @arg: user argument
2184  *
2185  *      This ioctl is used to manage job control. It permits a session
2186  *      leader to set this tty as the controlling tty for the session.
2187  *
2188  *      Locking:
2189  *              Takes tty_mutex() to protect tty instance
2190  *              Takes tasklist_lock internally to walk sessions
2191  *              Takes ->siglock() when updating signal->tty
2192  */
2193
2194 static int tiocsctty(struct tty_struct *tty, int arg)
2195 {
2196         int ret = 0;
2197         if (current->signal->leader && (task_session(current) == tty->session))
2198                 return ret;
2199
2200         mutex_lock(&tty_mutex);
2201         /*
2202          * The process must be a session leader and
2203          * not have a controlling tty already.
2204          */
2205         if (!current->signal->leader || current->signal->tty) {
2206                 ret = -EPERM;
2207                 goto unlock;
2208         }
2209
2210         if (tty->session) {
2211                 /*
2212                  * This tty is already the controlling
2213                  * tty for another session group!
2214                  */
2215                 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2216                         /*
2217                          * Steal it away
2218                          */
2219                         read_lock(&tasklist_lock);
2220                         session_clear_tty(tty->session);
2221                         read_unlock(&tasklist_lock);
2222                 } else {
2223                         ret = -EPERM;
2224                         goto unlock;
2225                 }
2226         }
2227         proc_set_tty(current, tty);
2228 unlock:
2229         mutex_unlock(&tty_mutex);
2230         return ret;
2231 }
2232
2233 /**
2234  *      tty_get_pgrp    -       return a ref counted pgrp pid
2235  *      @tty: tty to read
2236  *
2237  *      Returns a refcounted instance of the pid struct for the process
2238  *      group controlling the tty.
2239  */
2240
2241 struct pid *tty_get_pgrp(struct tty_struct *tty)
2242 {
2243         unsigned long flags;
2244         struct pid *pgrp;
2245
2246         spin_lock_irqsave(&tty->ctrl_lock, flags);
2247         pgrp = get_pid(tty->pgrp);
2248         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2249
2250         return pgrp;
2251 }
2252 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2253
2254 /**
2255  *      tiocgpgrp               -       get process group
2256  *      @tty: tty passed by user
2257  *      @real_tty: tty side of the tty pased by the user if a pty else the tty
2258  *      @p: returned pid
2259  *
2260  *      Obtain the process group of the tty. If there is no process group
2261  *      return an error.
2262  *
2263  *      Locking: none. Reference to current->signal->tty is safe.
2264  */
2265
2266 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2267 {
2268         struct pid *pid;
2269         int ret;
2270         /*
2271          * (tty == real_tty) is a cheap way of
2272          * testing if the tty is NOT a master pty.
2273          */
2274         if (tty == real_tty && current->signal->tty != real_tty)
2275                 return -ENOTTY;
2276         pid = tty_get_pgrp(real_tty);
2277         ret =  put_user(pid_vnr(pid), p);
2278         put_pid(pid);
2279         return ret;
2280 }
2281
2282 /**
2283  *      tiocspgrp               -       attempt to set process group
2284  *      @tty: tty passed by user
2285  *      @real_tty: tty side device matching tty passed by user
2286  *      @p: pid pointer
2287  *
2288  *      Set the process group of the tty to the session passed. Only
2289  *      permitted where the tty session is our session.
2290  *
2291  *      Locking: RCU, ctrl lock
2292  */
2293
2294 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2295 {
2296         struct pid *pgrp;
2297         pid_t pgrp_nr;
2298         int retval = tty_check_change(real_tty);
2299         unsigned long flags;
2300
2301         if (retval == -EIO)
2302                 return -ENOTTY;
2303         if (retval)
2304                 return retval;
2305         if (!current->signal->tty ||
2306             (current->signal->tty != real_tty) ||
2307             (real_tty->session != task_session(current)))
2308                 return -ENOTTY;
2309         if (get_user(pgrp_nr, p))
2310                 return -EFAULT;
2311         if (pgrp_nr < 0)
2312                 return -EINVAL;
2313         rcu_read_lock();
2314         pgrp = find_vpid(pgrp_nr);
2315         retval = -ESRCH;
2316         if (!pgrp)
2317                 goto out_unlock;
2318         retval = -EPERM;
2319         if (session_of_pgrp(pgrp) != task_session(current))
2320                 goto out_unlock;
2321         retval = 0;
2322         spin_lock_irqsave(&tty->ctrl_lock, flags);
2323         put_pid(real_tty->pgrp);
2324         real_tty->pgrp = get_pid(pgrp);
2325         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2326 out_unlock:
2327         rcu_read_unlock();
2328         return retval;
2329 }
2330
2331 /**
2332  *      tiocgsid                -       get session id
2333  *      @tty: tty passed by user
2334  *      @real_tty: tty side of the tty pased by the user if a pty else the tty
2335  *      @p: pointer to returned session id
2336  *
2337  *      Obtain the session id of the tty. If there is no session
2338  *      return an error.
2339  *
2340  *      Locking: none. Reference to current->signal->tty is safe.
2341  */
2342
2343 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2344 {
2345         /*
2346          * (tty == real_tty) is a cheap way of
2347          * testing if the tty is NOT a master pty.
2348         */
2349         if (tty == real_tty && current->signal->tty != real_tty)
2350                 return -ENOTTY;
2351         if (!real_tty->session)
2352                 return -ENOTTY;
2353         return put_user(pid_vnr(real_tty->session), p);
2354 }
2355
2356 /**
2357  *      tiocsetd        -       set line discipline
2358  *      @tty: tty device
2359  *      @p: pointer to user data
2360  *
2361  *      Set the line discipline according to user request.
2362  *
2363  *      Locking: see tty_set_ldisc, this function is just a helper
2364  */
2365
2366 static int tiocsetd(struct tty_struct *tty, int __user *p)
2367 {
2368         int ldisc;
2369         int ret;
2370
2371         if (get_user(ldisc, p))
2372                 return -EFAULT;
2373
2374         lock_kernel();
2375         ret = tty_set_ldisc(tty, ldisc);
2376         unlock_kernel();
2377
2378         return ret;
2379 }
2380
2381 /**
2382  *      send_break      -       performed time break
2383  *      @tty: device to break on
2384  *      @duration: timeout in mS
2385  *
2386  *      Perform a timed break on hardware that lacks its own driver level
2387  *      timed break functionality.
2388  *
2389  *      Locking:
2390  *              atomic_write_lock serializes
2391  *
2392  */
2393
2394 static int send_break(struct tty_struct *tty, unsigned int duration)
2395 {
2396         int retval;
2397
2398         if (tty->ops->break_ctl == NULL)
2399                 return 0;
2400
2401         if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2402                 retval = tty->ops->break_ctl(tty, duration);
2403         else {
2404                 /* Do the work ourselves */
2405                 if (tty_write_lock(tty, 0) < 0)
2406                         return -EINTR;
2407                 retval = tty->ops->break_ctl(tty, -1);
2408                 if (retval)
2409                         goto out;
2410                 if (!signal_pending(current))
2411                         msleep_interruptible(duration);
2412                 retval = tty->ops->break_ctl(tty, 0);
2413 out:
2414                 tty_write_unlock(tty);
2415                 if (signal_pending(current))
2416                         retval = -EINTR;
2417         }
2418         return retval;
2419 }
2420
2421 /**
2422  *      tty_tiocmget            -       get modem status
2423  *      @tty: tty device
2424  *      @file: user file pointer
2425  *      @p: pointer to result
2426  *
2427  *      Obtain the modem status bits from the tty driver if the feature
2428  *      is supported. Return -EINVAL if it is not available.
2429  *
2430  *      Locking: none (up to the driver)
2431  */
2432
2433 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
2434 {
2435         int retval = -EINVAL;
2436
2437         if (tty->ops->tiocmget) {
2438                 retval = tty->ops->tiocmget(tty, file);
2439
2440                 if (retval >= 0)
2441                         retval = put_user(retval, p);
2442         }
2443         return retval;
2444 }
2445
2446 /**
2447  *      tty_tiocmset            -       set modem status
2448  *      @tty: tty device
2449  *      @file: user file pointer
2450  *      @cmd: command - clear bits, set bits or set all
2451  *      @p: pointer to desired bits
2452  *
2453  *      Set the modem status bits from the tty driver if the feature
2454  *      is supported. Return -EINVAL if it is not available.
2455  *
2456  *      Locking: none (up to the driver)
2457  */
2458
2459 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
2460              unsigned __user *p)
2461 {
2462         int retval;
2463         unsigned int set, clear, val;
2464
2465         if (tty->ops->tiocmset == NULL)
2466                 return -EINVAL;
2467
2468         retval = get_user(val, p);
2469         if (retval)
2470                 return retval;
2471         set = clear = 0;
2472         switch (cmd) {
2473         case TIOCMBIS:
2474                 set = val;
2475                 break;
2476         case TIOCMBIC:
2477                 clear = val;
2478                 break;
2479         case TIOCMSET:
2480                 set = val;
2481                 clear = ~val;
2482                 break;
2483         }
2484         set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2485         clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2486         return tty->ops->tiocmset(tty, file, set, clear);
2487 }
2488
2489 /*
2490  * Split this up, as gcc can choke on it otherwise..
2491  */
2492 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2493 {
2494         struct tty_struct *tty, *real_tty;
2495         void __user *p = (void __user *)arg;
2496         int retval;
2497         struct tty_ldisc *ld;
2498         struct inode *inode = file->f_dentry->d_inode;
2499
2500         tty = (struct tty_struct *)file->private_data;
2501         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2502                 return -EINVAL;
2503
2504         real_tty = tty;
2505         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2506             tty->driver->subtype == PTY_TYPE_MASTER)
2507                 real_tty = tty->link;
2508
2509
2510         /*
2511          * Factor out some common prep work
2512          */
2513         switch (cmd) {
2514         case TIOCSETD:
2515         case TIOCSBRK:
2516         case TIOCCBRK:
2517         case TCSBRK:
2518         case TCSBRKP:
2519                 retval = tty_check_change(tty);
2520                 if (retval)
2521                         return retval;
2522                 if (cmd != TIOCCBRK) {
2523                         tty_wait_until_sent(tty, 0);
2524                         if (signal_pending(current))
2525                                 return -EINTR;
2526                 }
2527                 break;
2528         }
2529
2530         /*
2531          *      Now do the stuff.
2532          */
2533         switch (cmd) {
2534         case TIOCSTI:
2535                 return tiocsti(tty, p);
2536         case TIOCGWINSZ:
2537                 return tiocgwinsz(real_tty, p);
2538         case TIOCSWINSZ:
2539                 return tiocswinsz(tty, real_tty, p);
2540         case TIOCCONS:
2541                 return real_tty != tty ? -EINVAL : tioccons(file);
2542         case FIONBIO:
2543                 return fionbio(file, p);
2544         case TIOCEXCL:
2545                 set_bit(TTY_EXCLUSIVE, &tty->flags);
2546                 return 0;
2547         case TIOCNXCL:
2548                 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2549                 return 0;
2550         case TIOCNOTTY:
2551                 if (current->signal->tty != tty)
2552                         return -ENOTTY;
2553                 no_tty();
2554                 return 0;
2555         case TIOCSCTTY:
2556                 return tiocsctty(tty, arg);
2557         case TIOCGPGRP:
2558                 return tiocgpgrp(tty, real_tty, p);
2559         case TIOCSPGRP:
2560                 return tiocspgrp(tty, real_tty, p);
2561         case TIOCGSID:
2562                 return tiocgsid(tty, real_tty, p);
2563         case TIOCGETD:
2564                 return put_user(tty->ldisc.ops->num, (int __user *)p);
2565         case TIOCSETD:
2566                 return tiocsetd(tty, p);
2567         /*
2568          * Break handling
2569          */
2570         case TIOCSBRK:  /* Turn break on, unconditionally */
2571                 if (tty->ops->break_ctl)
2572                         return tty->ops->break_ctl(tty, -1);
2573                 return 0;
2574         case TIOCCBRK:  /* Turn break off, unconditionally */
2575                 if (tty->ops->break_ctl)
2576                         return tty->ops->break_ctl(tty, 0);
2577                 return 0;
2578         case TCSBRK:   /* SVID version: non-zero arg --> no break */
2579                 /* non-zero arg means wait for all output data
2580                  * to be sent (performed above) but don't send break.
2581                  * This is used by the tcdrain() termios function.
2582                  */
2583                 if (!arg)
2584                         return send_break(tty, 250);
2585                 return 0;
2586         case TCSBRKP:   /* support for POSIX tcsendbreak() */
2587                 return send_break(tty, arg ? arg*100 : 250);
2588
2589         case TIOCMGET:
2590                 return tty_tiocmget(tty, file, p);
2591         case TIOCMSET:
2592         case TIOCMBIC:
2593         case TIOCMBIS:
2594                 return tty_tiocmset(tty, file, cmd, p);
2595         case TCFLSH:
2596                 switch (arg) {
2597                 case TCIFLUSH:
2598                 case TCIOFLUSH:
2599                 /* flush tty buffer and allow ldisc to process ioctl */
2600                         tty_buffer_flush(tty);
2601                         break;
2602                 }
2603                 break;
2604         }
2605         if (tty->ops->ioctl) {
2606                 retval = (tty->ops->ioctl)(tty, file, cmd, arg);
2607                 if (retval != -ENOIOCTLCMD)
2608                         return retval;
2609         }
2610         ld = tty_ldisc_ref_wait(tty);
2611         retval = -EINVAL;
2612         if (ld->ops->ioctl) {
2613                 retval = ld->ops->ioctl(tty, file, cmd, arg);
2614                 if (retval == -ENOIOCTLCMD)
2615                         retval = -EINVAL;
2616         }
2617         tty_ldisc_deref(ld);
2618         return retval;
2619 }
2620
2621 #ifdef CONFIG_COMPAT
2622 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2623                                 unsigned long arg)
2624 {
2625         struct inode *inode = file->f_dentry->d_inode;
2626         struct tty_struct *tty = file->private_data;
2627         struct tty_ldisc *ld;
2628         int retval = -ENOIOCTLCMD;
2629
2630         if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2631                 return -EINVAL;
2632
2633         if (tty->ops->compat_ioctl) {
2634                 retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
2635                 if (retval != -ENOIOCTLCMD)
2636                         return retval;
2637         }
2638
2639         ld = tty_ldisc_ref_wait(tty);
2640         if (ld->ops->compat_ioctl)
2641                 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2642         tty_ldisc_deref(ld);
2643
2644         return retval;
2645 }
2646 #endif
2647
2648 /*
2649  * This implements the "Secure Attention Key" ---  the idea is to
2650  * prevent trojan horses by killing all processes associated with this
2651  * tty when the user hits the "Secure Attention Key".  Required for
2652  * super-paranoid applications --- see the Orange Book for more details.
2653  *
2654  * This code could be nicer; ideally it should send a HUP, wait a few
2655  * seconds, then send a INT, and then a KILL signal.  But you then
2656  * have to coordinate with the init process, since all processes associated
2657  * with the current tty must be dead before the new getty is allowed
2658  * to spawn.
2659  *
2660  * Now, if it would be correct ;-/ The current code has a nasty hole -
2661  * it doesn't catch files in flight. We may send the descriptor to ourselves
2662  * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2663  *
2664  * Nasty bug: do_SAK is being called in interrupt context.  This can
2665  * deadlock.  We punt it up to process context.  AKPM - 16Mar2001
2666  */
2667 void __do_SAK(struct tty_struct *tty)
2668 {
2669 #ifdef TTY_SOFT_SAK
2670         tty_hangup(tty);
2671 #else
2672         struct task_struct *g, *p;
2673         struct pid *session;
2674         int             i;
2675         struct file     *filp;
2676         struct fdtable *fdt;
2677
2678         if (!tty)
2679                 return;
2680         session = tty->session;
2681
2682         tty_ldisc_flush(tty);
2683
2684         tty_driver_flush_buffer(tty);
2685
2686         read_lock(&tasklist_lock);
2687         /* Kill the entire session */
2688         do_each_pid_task(session, PIDTYPE_SID, p) {
2689                 printk(KERN_NOTICE "SAK: killed process %d"
2690                         " (%s): task_session_nr(p)==tty->session\n",
2691                         task_pid_nr(p), p->comm);
2692                 send_sig(SIGKILL, p, 1);
2693         } while_each_pid_task(session, PIDTYPE_SID, p);
2694         /* Now kill any processes that happen to have the
2695          * tty open.
2696          */
2697         do_each_thread(g, p) {
2698                 if (p->signal->tty == tty) {
2699                         printk(KERN_NOTICE "SAK: killed process %d"
2700                             " (%s): task_session_nr(p)==tty->session\n",
2701                             task_pid_nr(p), p->comm);
2702                         send_sig(SIGKILL, p, 1);
2703                         continue;
2704                 }
2705                 task_lock(p);
2706                 if (p->files) {
2707                         /*
2708                          * We don't take a ref to the file, so we must
2709                          * hold ->file_lock instead.
2710                          */
2711                         spin_lock(&p->files->file_lock);
2712                         fdt = files_fdtable(p->files);
2713                         for (i = 0; i < fdt->max_fds; i++) {
2714                                 filp = fcheck_files(p->files, i);
2715                                 if (!filp)
2716                                         continue;
2717                                 if (filp->f_op->read == tty_read &&
2718                                     filp->private_data == tty) {
2719                                         printk(KERN_NOTICE "SAK: killed process %d"
2720                                             " (%s): fd#%d opened to the tty\n",
2721                                             task_pid_nr(p), p->comm, i);
2722                                         force_sig(SIGKILL, p);
2723                                         break;
2724                                 }
2725                         }
2726                         spin_unlock(&p->files->file_lock);
2727                 }
2728                 task_unlock(p);
2729         } while_each_thread(g, p);
2730         read_unlock(&tasklist_lock);
2731 #endif
2732 }
2733
2734 static void do_SAK_work(struct work_struct *work)
2735 {
2736         struct tty_struct *tty =
2737                 container_of(work, struct tty_struct, SAK_work);
2738         __do_SAK(tty);
2739 }
2740
2741 /*
2742  * The tq handling here is a little racy - tty->SAK_work may already be queued.
2743  * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2744  * the values which we write to it will be identical to the values which it
2745  * already has. --akpm
2746  */
2747 void do_SAK(struct tty_struct *tty)
2748 {
2749         if (!tty)
2750                 return;
2751         schedule_work(&tty->SAK_work);
2752 }
2753
2754 EXPORT_SYMBOL(do_SAK);
2755
2756 /**
2757  *      initialize_tty_struct
2758  *      @tty: tty to initialize
2759  *
2760  *      This subroutine initializes a tty structure that has been newly
2761  *      allocated.
2762  *
2763  *      Locking: none - tty in question must not be exposed at this point
2764  */
2765
2766 void initialize_tty_struct(struct tty_struct *tty,
2767                 struct tty_driver *driver, int idx)
2768 {
2769         memset(tty, 0, sizeof(struct tty_struct));
2770         kref_init(&tty->kref);
2771         tty->magic = TTY_MAGIC;
2772         tty_ldisc_init(tty);
2773         tty->session = NULL;
2774         tty->pgrp = NULL;
2775         tty->overrun_time = jiffies;
2776         tty->buf.head = tty->buf.tail = NULL;
2777         tty_buffer_init(tty);
2778         mutex_init(&tty->termios_mutex);
2779         init_waitqueue_head(&tty->write_wait);
2780         init_waitqueue_head(&tty->read_wait);
2781         INIT_WORK(&tty->hangup_work, do_tty_hangup);
2782         mutex_init(&tty->atomic_read_lock);
2783         mutex_init(&tty->atomic_write_lock);
2784         spin_lock_init(&tty->read_lock);
2785         spin_lock_init(&tty->ctrl_lock);
2786         INIT_LIST_HEAD(&tty->tty_files);
2787         INIT_WORK(&tty->SAK_work, do_SAK_work);
2788
2789         tty->driver = driver;
2790         tty->ops = driver->ops;
2791         tty->index = idx;
2792         tty_line_name(driver, idx, tty->name);
2793 }
2794
2795 /**
2796  *      tty_put_char    -       write one character to a tty
2797  *      @tty: tty
2798  *      @ch: character
2799  *
2800  *      Write one byte to the tty using the provided put_char method
2801  *      if present. Returns the number of characters successfully output.
2802  *
2803  *      Note: the specific put_char operation in the driver layer may go
2804  *      away soon. Don't call it directly, use this method
2805  */
2806
2807 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2808 {
2809         if (tty->ops->put_char)
2810                 return tty->ops->put_char(tty, ch);
2811         return tty->ops->write(tty, &ch, 1);
2812 }
2813 EXPORT_SYMBOL_GPL(tty_put_char);
2814
2815 struct class *tty_class;
2816
2817 /**
2818  *      tty_register_device - register a tty device
2819  *      @driver: the tty driver that describes the tty device
2820  *      @index: the index in the tty driver for this tty device
2821  *      @device: a struct device that is associated with this tty device.
2822  *              This field is optional, if there is no known struct device
2823  *              for this tty device it can be set to NULL safely.
2824  *
2825  *      Returns a pointer to the struct device for this tty device
2826  *      (or ERR_PTR(-EFOO) on error).
2827  *
2828  *      This call is required to be made to register an individual tty device
2829  *      if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set.  If
2830  *      that bit is not set, this function should not be called by a tty
2831  *      driver.
2832  *
2833  *      Locking: ??
2834  */
2835
2836 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2837                                    struct device *device)
2838 {
2839         char name[64];
2840         dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
2841
2842         if (index >= driver->num) {
2843                 printk(KERN_ERR "Attempt to register invalid tty line number "
2844                        " (%d).\n", index);
2845                 return ERR_PTR(-EINVAL);
2846         }
2847
2848         if (driver->type == TTY_DRIVER_TYPE_PTY)
2849                 pty_line_name(driver, index, name);
2850         else
2851                 tty_line_name(driver, index, name);
2852
2853         return device_create_drvdata(tty_class, device, dev, NULL, name);
2854 }
2855 EXPORT_SYMBOL(tty_register_device);
2856
2857 /**
2858  *      tty_unregister_device - unregister a tty device
2859  *      @driver: the tty driver that describes the tty device
2860  *      @index: the index in the tty driver for this tty device
2861  *
2862  *      If a tty device is registered with a call to tty_register_device() then
2863  *      this function must be called when the tty device is gone.
2864  *
2865  *      Locking: ??
2866  */
2867
2868 void tty_unregister_device(struct tty_driver *driver, unsigned index)
2869 {
2870         device_destroy(tty_class,
2871                 MKDEV(driver->major, driver->minor_start) + index);
2872 }
2873 EXPORT_SYMBOL(tty_unregister_device);
2874
2875 struct tty_driver *alloc_tty_driver(int lines)
2876 {
2877         struct tty_driver *driver;
2878
2879         driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
2880         if (driver) {
2881                 kref_init(&driver->kref);
2882                 driver->magic = TTY_DRIVER_MAGIC;
2883                 driver->num = lines;
2884                 /* later we'll move allocation of tables here */
2885         }
2886         return driver;
2887 }
2888 EXPORT_SYMBOL(alloc_tty_driver);
2889
2890 static void destruct_tty_driver(struct kref *kref)
2891 {
2892         struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
2893         int i;
2894         struct ktermios *tp;
2895         void *p;
2896
2897         if (driver->flags & TTY_DRIVER_INSTALLED) {
2898                 /*
2899                  * Free the termios and termios_locked structures because
2900                  * we don't want to get memory leaks when modular tty
2901                  * drivers are removed from the kernel.
2902                  */
2903                 for (i = 0; i < driver->num; i++) {
2904                         tp = driver->termios[i];
2905                         if (tp) {
2906                                 driver->termios[i] = NULL;
2907                                 kfree(tp);
2908                         }
2909                         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
2910                                 tty_unregister_device(driver, i);
2911                 }
2912                 p = driver->ttys;
2913                 proc_tty_unregister_driver(driver);
2914                 driver->ttys = NULL;
2915                 driver->termios = NULL;
2916                 kfree(p);
2917                 cdev_del(&driver->cdev);
2918         }
2919         kfree(driver);
2920 }
2921
2922 void tty_driver_kref_put(struct tty_driver *driver)
2923 {
2924         kref_put(&driver->kref, destruct_tty_driver);
2925 }
2926 EXPORT_SYMBOL(tty_driver_kref_put);
2927
2928 void tty_set_operations(struct tty_driver *driver,
2929                         const struct tty_operations *op)
2930 {
2931         driver->ops = op;
2932 };
2933 EXPORT_SYMBOL(tty_set_operations);
2934
2935 void put_tty_driver(struct tty_driver *d)
2936 {
2937         tty_driver_kref_put(d);
2938 }
2939 EXPORT_SYMBOL(put_tty_driver);
2940
2941 /*
2942  * Called by a tty driver to register itself.
2943  */
2944 int tty_register_driver(struct tty_driver *driver)
2945 {
2946         int error;
2947         int i;
2948         dev_t dev;
2949         void **p = NULL;
2950
2951         if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
2952                 p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
2953                 if (!p)
2954                         return -ENOMEM;
2955         }
2956
2957         if (!driver->major) {
2958                 error = alloc_chrdev_region(&dev, driver->minor_start,
2959                                                 driver->num, driver->name);
2960                 if (!error) {
2961                         driver->major = MAJOR(dev);
2962                         driver->minor_start = MINOR(dev);
2963                 }
2964         } else {
2965                 dev = MKDEV(driver->major, driver->minor_start);
2966                 error = register_chrdev_region(dev, driver->num, driver->name);
2967         }
2968         if (error < 0) {
2969                 kfree(p);
2970                 return error;
2971         }
2972
2973         if (p) {
2974                 driver->ttys = (struct tty_struct **)p;
2975                 driver->termios = (struct ktermios **)(p + driver->num);
2976         } else {
2977                 driver->ttys = NULL;
2978                 driver->termios = NULL;
2979         }
2980
2981         cdev_init(&driver->cdev, &tty_fops);
2982         driver->cdev.owner = driver->owner;
2983         error = cdev_add(&driver->cdev, dev, driver->num);
2984         if (error) {
2985                 unregister_chrdev_region(dev, driver->num);
2986                 driver->ttys = NULL;
2987                 driver->termios = NULL;
2988                 kfree(p);
2989                 return error;
2990         }
2991
2992         mutex_lock(&tty_mutex);
2993         list_add(&driver->tty_drivers, &tty_drivers);
2994         mutex_unlock(&tty_mutex);
2995
2996         if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
2997                 for (i = 0; i < driver->num; i++)
2998                     tty_register_device(driver, i, NULL);
2999         }
3000         proc_tty_register_driver(driver);
3001         driver->flags |= TTY_DRIVER_INSTALLED;
3002         return 0;
3003 }
3004
3005 EXPORT_SYMBOL(tty_register_driver);
3006
3007 /*
3008  * Called by a tty driver to unregister itself.
3009  */
3010 int tty_unregister_driver(struct tty_driver *driver)
3011 {
3012 #if 0
3013         /* FIXME */
3014         if (driver->refcount)
3015                 return -EBUSY;
3016 #endif
3017         unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3018                                 driver->num);
3019         mutex_lock(&tty_mutex);
3020         list_del(&driver->tty_drivers);
3021         mutex_unlock(&tty_mutex);
3022         return 0;
3023 }
3024
3025 EXPORT_SYMBOL(tty_unregister_driver);
3026
3027 dev_t tty_devnum(struct tty_struct *tty)
3028 {
3029         return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3030 }
3031 EXPORT_SYMBOL(tty_devnum);
3032
3033 void proc_clear_tty(struct task_struct *p)
3034 {
3035         unsigned long flags;
3036         struct tty_struct *tty;
3037         spin_lock_irqsave(&p->sighand->siglock, flags);
3038         tty = p->signal->tty;
3039         p->signal->tty = NULL;
3040         spin_unlock_irqrestore(&p->sighand->siglock, flags);
3041         tty_kref_put(tty);
3042 }
3043
3044 /* Called under the sighand lock */
3045
3046 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3047 {
3048         if (tty) {
3049                 unsigned long flags;
3050                 /* We should not have a session or pgrp to put here but.... */
3051                 spin_lock_irqsave(&tty->ctrl_lock, flags);
3052                 put_pid(tty->session);
3053                 put_pid(tty->pgrp);
3054                 tty->pgrp = get_pid(task_pgrp(tsk));
3055                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3056                 tty->session = get_pid(task_session(tsk));
3057                 if (tsk->signal->tty) {
3058                         printk(KERN_DEBUG "tty not NULL!!\n");
3059                         tty_kref_put(tsk->signal->tty);
3060                 }
3061         }
3062         put_pid(tsk->signal->tty_old_pgrp);
3063         tsk->signal->tty = tty_kref_get(tty);
3064         tsk->signal->tty_old_pgrp = NULL;
3065 }
3066
3067 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3068 {
3069         spin_lock_irq(&tsk->sighand->siglock);
3070         __proc_set_tty(tsk, tty);
3071         spin_unlock_irq(&tsk->sighand->siglock);
3072 }
3073
3074 struct tty_struct *get_current_tty(void)
3075 {
3076         struct tty_struct *tty;
3077         unsigned long flags;
3078
3079         spin_lock_irqsave(&current->sighand->siglock, flags);
3080         tty = tty_kref_get(current->signal->tty);
3081         spin_unlock_irqrestore(&current->sighand->siglock, flags);
3082         return tty;
3083 }
3084 EXPORT_SYMBOL_GPL(get_current_tty);
3085
3086 void tty_default_fops(struct file_operations *fops)
3087 {
3088         *fops = tty_fops;
3089 }
3090
3091 /*
3092  * Initialize the console device. This is called *early*, so
3093  * we can't necessarily depend on lots of kernel help here.
3094  * Just do some early initializations, and do the complex setup
3095  * later.
3096  */
3097 void __init console_init(void)
3098 {
3099         initcall_t *call;
3100
3101         /* Setup the default TTY line discipline. */
3102         tty_ldisc_begin();
3103
3104         /*
3105          * set up the console device so that later boot sequences can
3106          * inform about problems etc..
3107          */
3108         call = __con_initcall_start;
3109         while (call < __con_initcall_end) {
3110                 (*call)();
3111                 call++;
3112         }
3113 }
3114
3115 static int __init tty_class_init(void)
3116 {
3117         tty_class = class_create(THIS_MODULE, "tty");
3118         if (IS_ERR(tty_class))
3119                 return PTR_ERR(tty_class);
3120         return 0;
3121 }
3122
3123 postcore_initcall(tty_class_init);
3124
3125 /* 3/2004 jmc: why do these devices exist? */
3126
3127 static struct cdev tty_cdev, console_cdev;
3128
3129 /*
3130  * Ok, now we can initialize the rest of the tty devices and can count
3131  * on memory allocations, interrupts etc..
3132  */
3133 static int __init tty_init(void)
3134 {
3135         cdev_init(&tty_cdev, &tty_fops);
3136         if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3137             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3138                 panic("Couldn't register /dev/tty driver\n");
3139         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
3140                               "tty");
3141
3142         cdev_init(&console_cdev, &console_fops);
3143         if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3144             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3145                 panic("Couldn't register /dev/console driver\n");
3146         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3147                               "console");
3148
3149 #ifdef CONFIG_VT
3150         vty_init(&console_fops);
3151 #endif
3152         return 0;
3153 }
3154 module_init(tty_init);