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[/] [test_project/] [trunk/] [linux_sd_driver/] [drivers/] [char/] [pty.c] - Blame information for rev 62

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1 62 marcus.erl
/*
2
 *  linux/drivers/char/pty.c
3
 *
4
 *  Copyright (C) 1991, 1992  Linus Torvalds
5
 *
6
 *  Added support for a Unix98-style ptmx device.
7
 *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
8
 *  Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to
9
 *      waiting writers -- Sapan Bhatia <sapan@corewars.org>
10
 *
11
 *
12
 */
13
 
14
#include <linux/module.h>       /* For EXPORT_SYMBOL */
15
 
16
#include <linux/errno.h>
17
#include <linux/interrupt.h>
18
#include <linux/tty.h>
19
#include <linux/tty_flip.h>
20
#include <linux/fcntl.h>
21
#include <linux/string.h>
22
#include <linux/major.h>
23
#include <linux/mm.h>
24
#include <linux/init.h>
25
#include <linux/sysctl.h>
26
 
27
#include <asm/uaccess.h>
28
#include <asm/system.h>
29
#include <linux/bitops.h>
30
#include <linux/devpts_fs.h>
31
 
32
/* These are global because they are accessed in tty_io.c */
33
#ifdef CONFIG_UNIX98_PTYS
34
struct tty_driver *ptm_driver;
35
static struct tty_driver *pts_driver;
36
#endif
37
 
38
static void pty_close(struct tty_struct * tty, struct file * filp)
39
{
40
        if (!tty)
41
                return;
42
        if (tty->driver->subtype == PTY_TYPE_MASTER) {
43
                if (tty->count > 1)
44
                        printk("master pty_close: count = %d!!\n", tty->count);
45
        } else {
46
                if (tty->count > 2)
47
                        return;
48
        }
49
        wake_up_interruptible(&tty->read_wait);
50
        wake_up_interruptible(&tty->write_wait);
51
        tty->packet = 0;
52
        if (!tty->link)
53
                return;
54
        tty->link->packet = 0;
55
        set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
56
        wake_up_interruptible(&tty->link->read_wait);
57
        wake_up_interruptible(&tty->link->write_wait);
58
        if (tty->driver->subtype == PTY_TYPE_MASTER) {
59
                set_bit(TTY_OTHER_CLOSED, &tty->flags);
60
#ifdef CONFIG_UNIX98_PTYS
61
                if (tty->driver == ptm_driver)
62
                        devpts_pty_kill(tty->index);
63
#endif
64
                tty_vhangup(tty->link);
65
        }
66
}
67
 
68
/*
69
 * The unthrottle routine is called by the line discipline to signal
70
 * that it can receive more characters.  For PTY's, the TTY_THROTTLED
71
 * flag is always set, to force the line discipline to always call the
72
 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
73
 * characters in the queue.  This is necessary since each time this
74
 * happens, we need to wake up any sleeping processes that could be
75
 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
76
 * for the pty buffer to be drained.
77
 */
78
static void pty_unthrottle(struct tty_struct * tty)
79
{
80
        struct tty_struct *o_tty = tty->link;
81
 
82
        if (!o_tty)
83
                return;
84
 
85
        tty_wakeup(o_tty);
86
        set_bit(TTY_THROTTLED, &tty->flags);
87
}
88
 
89
/*
90
 * WSH 05/24/97: modified to
91
 *   (1) use space in tty->flip instead of a shared temp buffer
92
 *       The flip buffers aren't being used for a pty, so there's lots
93
 *       of space available.  The buffer is protected by a per-pty
94
 *       semaphore that should almost never come under contention.
95
 *   (2) avoid redundant copying for cases where count >> receive_room
96
 * N.B. Calls from user space may now return an error code instead of
97
 * a count.
98
 *
99
 * FIXME: Our pty_write method is called with our ldisc lock held but
100
 * not our partners. We can't just take the other one blindly without
101
 * risking deadlocks.
102
 */
103
static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
104
{
105
        struct tty_struct *to = tty->link;
106
        int     c;
107
 
108
        if (!to || tty->stopped)
109
                return 0;
110
 
111
        c = to->receive_room;
112
        if (c > count)
113
                c = count;
114
        to->ldisc.receive_buf(to, buf, NULL, c);
115
 
116
        return c;
117
}
118
 
119
static int pty_write_room(struct tty_struct *tty)
120
{
121
        struct tty_struct *to = tty->link;
122
 
123
        if (!to || tty->stopped)
124
                return 0;
125
 
126
        return to->receive_room;
127
}
128
 
129
/*
130
 *      WSH 05/24/97:  Modified for asymmetric MASTER/SLAVE behavior
131
 *      The chars_in_buffer() value is used by the ldisc select() function
132
 *      to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
133
 *      The pty driver chars_in_buffer() Master/Slave must behave differently:
134
 *
135
 *      The Master side needs to allow typed-ahead commands to accumulate
136
 *      while being canonicalized, so we report "our buffer" as empty until
137
 *      some threshold is reached, and then report the count. (Any count >
138
 *      WAKEUP_CHARS is regarded by select() as "full".)  To avoid deadlock
139
 *      the count returned must be 0 if no canonical data is available to be
140
 *      read. (The N_TTY ldisc.chars_in_buffer now knows this.)
141
 *
142
 *      The Slave side passes all characters in raw mode to the Master side's
143
 *      buffer where they can be read immediately, so in this case we can
144
 *      return the true count in the buffer.
145
 */
146
static int pty_chars_in_buffer(struct tty_struct *tty)
147
{
148
        struct tty_struct *to = tty->link;
149
        int count;
150
 
151
        /* We should get the line discipline lock for "tty->link" */
152
        if (!to || !to->ldisc.chars_in_buffer)
153
                return 0;
154
 
155
        /* The ldisc must report 0 if no characters available to be read */
156
        count = to->ldisc.chars_in_buffer(to);
157
 
158
        if (tty->driver->subtype == PTY_TYPE_SLAVE) return count;
159
 
160
        /* Master side driver ... if the other side's read buffer is less than
161
         * half full, return 0 to allow writers to proceed; otherwise return
162
         * the count.  This leaves a comfortable margin to avoid overflow,
163
         * and still allows half a buffer's worth of typed-ahead commands.
164
         */
165
        return ((count < N_TTY_BUF_SIZE/2) ? 0 : count);
166
}
167
 
168
/* Set the lock flag on a pty */
169
static int pty_set_lock(struct tty_struct *tty, int __user * arg)
170
{
171
        int val;
172
        if (get_user(val,arg))
173
                return -EFAULT;
174
        if (val)
175
                set_bit(TTY_PTY_LOCK, &tty->flags);
176
        else
177
                clear_bit(TTY_PTY_LOCK, &tty->flags);
178
        return 0;
179
}
180
 
181
static void pty_flush_buffer(struct tty_struct *tty)
182
{
183
        struct tty_struct *to = tty->link;
184
 
185
        if (!to)
186
                return;
187
 
188
        if (to->ldisc.flush_buffer)
189
                to->ldisc.flush_buffer(to);
190
 
191
        if (to->packet) {
192
                tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
193
                wake_up_interruptible(&to->read_wait);
194
        }
195
}
196
 
197
static int pty_open(struct tty_struct *tty, struct file * filp)
198
{
199
        int     retval = -ENODEV;
200
 
201
        if (!tty || !tty->link)
202
                goto out;
203
 
204
        retval = -EIO;
205
        if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
206
                goto out;
207
        if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
208
                goto out;
209
        if (tty->link->count != 1)
210
                goto out;
211
 
212
        clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
213
        set_bit(TTY_THROTTLED, &tty->flags);
214
        set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
215
        retval = 0;
216
out:
217
        return retval;
218
}
219
 
220
static void pty_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
221
{
222
        tty->termios->c_cflag &= ~(CSIZE | PARENB);
223
        tty->termios->c_cflag |= (CS8 | CREAD);
224
}
225
 
226
static const struct tty_operations pty_ops = {
227
        .open = pty_open,
228
        .close = pty_close,
229
        .write = pty_write,
230
        .write_room = pty_write_room,
231
        .flush_buffer = pty_flush_buffer,
232
        .chars_in_buffer = pty_chars_in_buffer,
233
        .unthrottle = pty_unthrottle,
234
        .set_termios = pty_set_termios,
235
};
236
 
237
/* Traditional BSD devices */
238
#ifdef CONFIG_LEGACY_PTYS
239
static struct tty_driver *pty_driver, *pty_slave_driver;
240
 
241
static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
242
                         unsigned int cmd, unsigned long arg)
243
{
244
        switch (cmd) {
245
        case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
246
                return pty_set_lock(tty, (int __user *) arg);
247
        }
248
        return -ENOIOCTLCMD;
249
}
250
 
251
static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
252
module_param(legacy_count, int, 0);
253
 
254
static void __init legacy_pty_init(void)
255
{
256
        if (legacy_count <= 0)
257
                return;
258
 
259
        pty_driver = alloc_tty_driver(legacy_count);
260
        if (!pty_driver)
261
                panic("Couldn't allocate pty driver");
262
 
263
        pty_slave_driver = alloc_tty_driver(legacy_count);
264
        if (!pty_slave_driver)
265
                panic("Couldn't allocate pty slave driver");
266
 
267
        pty_driver->owner = THIS_MODULE;
268
        pty_driver->driver_name = "pty_master";
269
        pty_driver->name = "pty";
270
        pty_driver->major = PTY_MASTER_MAJOR;
271
        pty_driver->minor_start = 0;
272
        pty_driver->type = TTY_DRIVER_TYPE_PTY;
273
        pty_driver->subtype = PTY_TYPE_MASTER;
274
        pty_driver->init_termios = tty_std_termios;
275
        pty_driver->init_termios.c_iflag = 0;
276
        pty_driver->init_termios.c_oflag = 0;
277
        pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
278
        pty_driver->init_termios.c_lflag = 0;
279
        pty_driver->init_termios.c_ispeed = 38400;
280
        pty_driver->init_termios.c_ospeed = 38400;
281
        pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
282
        pty_driver->other = pty_slave_driver;
283
        tty_set_operations(pty_driver, &pty_ops);
284
        pty_driver->ioctl = pty_bsd_ioctl;
285
 
286
        pty_slave_driver->owner = THIS_MODULE;
287
        pty_slave_driver->driver_name = "pty_slave";
288
        pty_slave_driver->name = "ttyp";
289
        pty_slave_driver->major = PTY_SLAVE_MAJOR;
290
        pty_slave_driver->minor_start = 0;
291
        pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
292
        pty_slave_driver->subtype = PTY_TYPE_SLAVE;
293
        pty_slave_driver->init_termios = tty_std_termios;
294
        pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
295
        pty_slave_driver->init_termios.c_ispeed = 38400;
296
        pty_slave_driver->init_termios.c_ospeed = 38400;
297
        pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
298
                                        TTY_DRIVER_REAL_RAW;
299
        pty_slave_driver->other = pty_driver;
300
        tty_set_operations(pty_slave_driver, &pty_ops);
301
 
302
        if (tty_register_driver(pty_driver))
303
                panic("Couldn't register pty driver");
304
        if (tty_register_driver(pty_slave_driver))
305
                panic("Couldn't register pty slave driver");
306
}
307
#else
308
static inline void legacy_pty_init(void) { }
309
#endif
310
 
311
/* Unix98 devices */
312
#ifdef CONFIG_UNIX98_PTYS
313
/*
314
 * sysctl support for setting limits on the number of Unix98 ptys allocated.
315
 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
316
 */
317
int pty_limit = NR_UNIX98_PTY_DEFAULT;
318
static int pty_limit_min = 0;
319
static int pty_limit_max = NR_UNIX98_PTY_MAX;
320
 
321
static struct ctl_table pty_table[] = {
322
        {
323
                .ctl_name       = PTY_MAX,
324
                .procname       = "max",
325
                .maxlen         = sizeof(int),
326
                .mode           = 0644,
327
                .data           = &pty_limit,
328
                .proc_handler   = &proc_dointvec_minmax,
329
                .strategy       = &sysctl_intvec,
330
                .extra1         = &pty_limit_min,
331
                .extra2         = &pty_limit_max,
332
        }, {
333
                .ctl_name       = PTY_NR,
334
                .procname       = "nr",
335
                .maxlen         = sizeof(int),
336
                .mode           = 0444,
337
                .proc_handler   = &proc_dointvec,
338
        }, {
339
                .ctl_name       = 0
340
        }
341
};
342
 
343
static struct ctl_table pty_kern_table[] = {
344
        {
345
                .ctl_name       = KERN_PTY,
346
                .procname       = "pty",
347
                .mode           = 0555,
348
                .child          = pty_table,
349
        },
350
        {}
351
};
352
 
353
static struct ctl_table pty_root_table[] = {
354
        {
355
                .ctl_name       = CTL_KERN,
356
                .procname       = "kernel",
357
                .mode           = 0555,
358
                .child          = pty_kern_table,
359
        },
360
        {}
361
};
362
 
363
 
364
static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
365
                            unsigned int cmd, unsigned long arg)
366
{
367
        switch (cmd) {
368
        case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
369
                return pty_set_lock(tty, (int __user *)arg);
370
        case TIOCGPTN: /* Get PT Number */
371
                return put_user(tty->index, (unsigned int __user *)arg);
372
        }
373
 
374
        return -ENOIOCTLCMD;
375
}
376
 
377
static void __init unix98_pty_init(void)
378
{
379
        ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
380
        if (!ptm_driver)
381
                panic("Couldn't allocate Unix98 ptm driver");
382
        pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
383
        if (!pts_driver)
384
                panic("Couldn't allocate Unix98 pts driver");
385
 
386
        ptm_driver->owner = THIS_MODULE;
387
        ptm_driver->driver_name = "pty_master";
388
        ptm_driver->name = "ptm";
389
        ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
390
        ptm_driver->minor_start = 0;
391
        ptm_driver->type = TTY_DRIVER_TYPE_PTY;
392
        ptm_driver->subtype = PTY_TYPE_MASTER;
393
        ptm_driver->init_termios = tty_std_termios;
394
        ptm_driver->init_termios.c_iflag = 0;
395
        ptm_driver->init_termios.c_oflag = 0;
396
        ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
397
        ptm_driver->init_termios.c_lflag = 0;
398
        ptm_driver->init_termios.c_ispeed = 38400;
399
        ptm_driver->init_termios.c_ospeed = 38400;
400
        ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
401
                TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
402
        ptm_driver->other = pts_driver;
403
        tty_set_operations(ptm_driver, &pty_ops);
404
        ptm_driver->ioctl = pty_unix98_ioctl;
405
 
406
        pts_driver->owner = THIS_MODULE;
407
        pts_driver->driver_name = "pty_slave";
408
        pts_driver->name = "pts";
409
        pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
410
        pts_driver->minor_start = 0;
411
        pts_driver->type = TTY_DRIVER_TYPE_PTY;
412
        pts_driver->subtype = PTY_TYPE_SLAVE;
413
        pts_driver->init_termios = tty_std_termios;
414
        pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
415
        pts_driver->init_termios.c_ispeed = 38400;
416
        pts_driver->init_termios.c_ospeed = 38400;
417
        pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
418
                TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
419
        pts_driver->other = ptm_driver;
420
        tty_set_operations(pts_driver, &pty_ops);
421
 
422
        if (tty_register_driver(ptm_driver))
423
                panic("Couldn't register Unix98 ptm driver");
424
        if (tty_register_driver(pts_driver))
425
                panic("Couldn't register Unix98 pts driver");
426
 
427
        pty_table[1].data = &ptm_driver->refcount;
428
        register_sysctl_table(pty_root_table);
429
}
430
#else
431
static inline void unix98_pty_init(void) { }
432
#endif
433
 
434
static int __init pty_init(void)
435
{
436
        legacy_pty_init();
437
        unix98_pty_init();
438
        return 0;
439
}
440
module_init(pty_init);

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