Commit | Line | Data |
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1da177e4 LT |
1 | /* |
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 | ||
1da177e4 LT |
14 | #include <linux/module.h> /* For EXPORT_SYMBOL */ |
15 | ||
16 | #include <linux/errno.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/interrupt.h> | |
19 | #include <linux/tty.h> | |
20 | #include <linux/tty_flip.h> | |
21 | #include <linux/fcntl.h> | |
22 | #include <linux/string.h> | |
23 | #include <linux/major.h> | |
24 | #include <linux/mm.h> | |
25 | #include <linux/init.h> | |
1da177e4 LT |
26 | #include <linux/sysctl.h> |
27 | ||
28 | #include <asm/uaccess.h> | |
29 | #include <asm/system.h> | |
30 | #include <linux/bitops.h> | |
31 | #include <linux/devpts_fs.h> | |
32 | ||
33 | /* These are global because they are accessed in tty_io.c */ | |
34 | #ifdef CONFIG_UNIX98_PTYS | |
35 | struct tty_driver *ptm_driver; | |
36 | static struct tty_driver *pts_driver; | |
37 | #endif | |
38 | ||
39 | static void pty_close(struct tty_struct * tty, struct file * filp) | |
40 | { | |
41 | if (!tty) | |
42 | return; | |
43 | if (tty->driver->subtype == PTY_TYPE_MASTER) { | |
44 | if (tty->count > 1) | |
45 | printk("master pty_close: count = %d!!\n", tty->count); | |
46 | } else { | |
47 | if (tty->count > 2) | |
48 | return; | |
49 | } | |
50 | wake_up_interruptible(&tty->read_wait); | |
51 | wake_up_interruptible(&tty->write_wait); | |
52 | tty->packet = 0; | |
53 | if (!tty->link) | |
54 | return; | |
55 | tty->link->packet = 0; | |
56 | set_bit(TTY_OTHER_CLOSED, &tty->link->flags); | |
57 | wake_up_interruptible(&tty->link->read_wait); | |
58 | wake_up_interruptible(&tty->link->write_wait); | |
59 | if (tty->driver->subtype == PTY_TYPE_MASTER) { | |
60 | set_bit(TTY_OTHER_CLOSED, &tty->flags); | |
61 | #ifdef CONFIG_UNIX98_PTYS | |
62 | if (tty->driver == ptm_driver) | |
63 | devpts_pty_kill(tty->index); | |
64 | #endif | |
65 | tty_vhangup(tty->link); | |
66 | } | |
67 | } | |
68 | ||
69 | /* | |
70 | * The unthrottle routine is called by the line discipline to signal | |
71 | * that it can receive more characters. For PTY's, the TTY_THROTTLED | |
72 | * flag is always set, to force the line discipline to always call the | |
73 | * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE | |
74 | * characters in the queue. This is necessary since each time this | |
75 | * happens, we need to wake up any sleeping processes that could be | |
76 | * (1) trying to send data to the pty, or (2) waiting in wait_until_sent() | |
77 | * for the pty buffer to be drained. | |
78 | */ | |
79 | static void pty_unthrottle(struct tty_struct * tty) | |
80 | { | |
81 | struct tty_struct *o_tty = tty->link; | |
82 | ||
83 | if (!o_tty) | |
84 | return; | |
85 | ||
86 | tty_wakeup(o_tty); | |
87 | set_bit(TTY_THROTTLED, &tty->flags); | |
88 | } | |
89 | ||
90 | /* | |
91 | * WSH 05/24/97: modified to | |
92 | * (1) use space in tty->flip instead of a shared temp buffer | |
93 | * The flip buffers aren't being used for a pty, so there's lots | |
94 | * of space available. The buffer is protected by a per-pty | |
95 | * semaphore that should almost never come under contention. | |
96 | * (2) avoid redundant copying for cases where count >> receive_room | |
97 | * N.B. Calls from user space may now return an error code instead of | |
98 | * a count. | |
99 | * | |
100 | * FIXME: Our pty_write method is called with our ldisc lock held but | |
101 | * not our partners. We can't just take the other one blindly without | |
817d6d3b | 102 | * risking deadlocks. |
1da177e4 LT |
103 | */ |
104 | static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count) | |
105 | { | |
106 | struct tty_struct *to = tty->link; | |
107 | int c; | |
108 | ||
109 | if (!to || tty->stopped) | |
110 | return 0; | |
111 | ||
33f0f88f | 112 | c = to->receive_room; |
1da177e4 LT |
113 | if (c > count) |
114 | c = count; | |
115 | to->ldisc.receive_buf(to, buf, NULL, c); | |
116 | ||
117 | return c; | |
118 | } | |
119 | ||
120 | static int pty_write_room(struct tty_struct *tty) | |
121 | { | |
122 | struct tty_struct *to = tty->link; | |
123 | ||
124 | if (!to || tty->stopped) | |
125 | return 0; | |
126 | ||
33f0f88f | 127 | return to->receive_room; |
1da177e4 LT |
128 | } |
129 | ||
130 | /* | |
131 | * WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior | |
132 | * The chars_in_buffer() value is used by the ldisc select() function | |
133 | * to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256). | |
134 | * The pty driver chars_in_buffer() Master/Slave must behave differently: | |
135 | * | |
136 | * The Master side needs to allow typed-ahead commands to accumulate | |
137 | * while being canonicalized, so we report "our buffer" as empty until | |
138 | * some threshold is reached, and then report the count. (Any count > | |
139 | * WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock | |
140 | * the count returned must be 0 if no canonical data is available to be | |
141 | * read. (The N_TTY ldisc.chars_in_buffer now knows this.) | |
142 | * | |
143 | * The Slave side passes all characters in raw mode to the Master side's | |
144 | * buffer where they can be read immediately, so in this case we can | |
145 | * return the true count in the buffer. | |
146 | */ | |
147 | static int pty_chars_in_buffer(struct tty_struct *tty) | |
148 | { | |
149 | struct tty_struct *to = tty->link; | |
1da177e4 LT |
150 | int count; |
151 | ||
152 | /* We should get the line discipline lock for "tty->link" */ | |
ff55fe20 | 153 | if (!to || !to->ldisc.chars_in_buffer) |
1da177e4 LT |
154 | return 0; |
155 | ||
156 | /* The ldisc must report 0 if no characters available to be read */ | |
ff55fe20 | 157 | count = to->ldisc.chars_in_buffer(to); |
1da177e4 LT |
158 | |
159 | if (tty->driver->subtype == PTY_TYPE_SLAVE) return count; | |
160 | ||
161 | /* Master side driver ... if the other side's read buffer is less than | |
162 | * half full, return 0 to allow writers to proceed; otherwise return | |
163 | * the count. This leaves a comfortable margin to avoid overflow, | |
164 | * and still allows half a buffer's worth of typed-ahead commands. | |
165 | */ | |
166 | return ((count < N_TTY_BUF_SIZE/2) ? 0 : count); | |
167 | } | |
168 | ||
169 | /* Set the lock flag on a pty */ | |
170 | static int pty_set_lock(struct tty_struct *tty, int __user * arg) | |
171 | { | |
172 | int val; | |
173 | if (get_user(val,arg)) | |
174 | return -EFAULT; | |
175 | if (val) | |
176 | set_bit(TTY_PTY_LOCK, &tty->flags); | |
177 | else | |
178 | clear_bit(TTY_PTY_LOCK, &tty->flags); | |
179 | return 0; | |
180 | } | |
181 | ||
182 | static void pty_flush_buffer(struct tty_struct *tty) | |
183 | { | |
184 | struct tty_struct *to = tty->link; | |
185 | ||
186 | if (!to) | |
187 | return; | |
188 | ||
189 | if (to->ldisc.flush_buffer) | |
190 | to->ldisc.flush_buffer(to); | |
191 | ||
192 | if (to->packet) { | |
193 | tty->ctrl_status |= TIOCPKT_FLUSHWRITE; | |
194 | wake_up_interruptible(&to->read_wait); | |
195 | } | |
196 | } | |
197 | ||
198 | static int pty_open(struct tty_struct *tty, struct file * filp) | |
199 | { | |
200 | int retval = -ENODEV; | |
201 | ||
202 | if (!tty || !tty->link) | |
203 | goto out; | |
204 | ||
205 | retval = -EIO; | |
206 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
207 | goto out; | |
208 | if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) | |
209 | goto out; | |
210 | if (tty->link->count != 1) | |
211 | goto out; | |
212 | ||
213 | clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); | |
214 | set_bit(TTY_THROTTLED, &tty->flags); | |
215 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); | |
216 | retval = 0; | |
217 | out: | |
218 | return retval; | |
219 | } | |
220 | ||
221 | static void pty_set_termios(struct tty_struct *tty, struct termios *old_termios) | |
222 | { | |
223 | tty->termios->c_cflag &= ~(CSIZE | PARENB); | |
224 | tty->termios->c_cflag |= (CS8 | CREAD); | |
225 | } | |
226 | ||
227 | static struct tty_operations pty_ops = { | |
228 | .open = pty_open, | |
229 | .close = pty_close, | |
230 | .write = pty_write, | |
231 | .write_room = pty_write_room, | |
232 | .flush_buffer = pty_flush_buffer, | |
233 | .chars_in_buffer = pty_chars_in_buffer, | |
234 | .unthrottle = pty_unthrottle, | |
235 | .set_termios = pty_set_termios, | |
236 | }; | |
237 | ||
238 | /* Traditional BSD devices */ | |
239 | #ifdef CONFIG_LEGACY_PTYS | |
240 | static struct tty_driver *pty_driver, *pty_slave_driver; | |
241 | ||
242 | static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file, | |
243 | unsigned int cmd, unsigned long arg) | |
244 | { | |
245 | switch (cmd) { | |
246 | case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ | |
247 | return pty_set_lock(tty, (int __user *) arg); | |
248 | } | |
249 | return -ENOIOCTLCMD; | |
250 | } | |
251 | ||
252 | static void __init legacy_pty_init(void) | |
253 | { | |
254 | ||
255 | pty_driver = alloc_tty_driver(NR_PTYS); | |
256 | if (!pty_driver) | |
257 | panic("Couldn't allocate pty driver"); | |
258 | ||
259 | pty_slave_driver = alloc_tty_driver(NR_PTYS); | |
260 | if (!pty_slave_driver) | |
261 | panic("Couldn't allocate pty slave driver"); | |
262 | ||
263 | pty_driver->owner = THIS_MODULE; | |
264 | pty_driver->driver_name = "pty_master"; | |
265 | pty_driver->name = "pty"; | |
1da177e4 LT |
266 | pty_driver->major = PTY_MASTER_MAJOR; |
267 | pty_driver->minor_start = 0; | |
268 | pty_driver->type = TTY_DRIVER_TYPE_PTY; | |
269 | pty_driver->subtype = PTY_TYPE_MASTER; | |
270 | pty_driver->init_termios = tty_std_termios; | |
271 | pty_driver->init_termios.c_iflag = 0; | |
272 | pty_driver->init_termios.c_oflag = 0; | |
273 | pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; | |
274 | pty_driver->init_termios.c_lflag = 0; | |
275 | pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW; | |
276 | pty_driver->other = pty_slave_driver; | |
277 | tty_set_operations(pty_driver, &pty_ops); | |
278 | pty_driver->ioctl = pty_bsd_ioctl; | |
279 | ||
280 | pty_slave_driver->owner = THIS_MODULE; | |
281 | pty_slave_driver->driver_name = "pty_slave"; | |
282 | pty_slave_driver->name = "ttyp"; | |
1da177e4 LT |
283 | pty_slave_driver->major = PTY_SLAVE_MAJOR; |
284 | pty_slave_driver->minor_start = 0; | |
285 | pty_slave_driver->type = TTY_DRIVER_TYPE_PTY; | |
286 | pty_slave_driver->subtype = PTY_TYPE_SLAVE; | |
287 | pty_slave_driver->init_termios = tty_std_termios; | |
288 | pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; | |
289 | pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS | | |
290 | TTY_DRIVER_REAL_RAW; | |
291 | pty_slave_driver->other = pty_driver; | |
292 | tty_set_operations(pty_slave_driver, &pty_ops); | |
293 | ||
294 | if (tty_register_driver(pty_driver)) | |
295 | panic("Couldn't register pty driver"); | |
296 | if (tty_register_driver(pty_slave_driver)) | |
297 | panic("Couldn't register pty slave driver"); | |
298 | } | |
299 | #else | |
300 | static inline void legacy_pty_init(void) { } | |
301 | #endif | |
302 | ||
303 | /* Unix98 devices */ | |
304 | #ifdef CONFIG_UNIX98_PTYS | |
305 | /* | |
306 | * sysctl support for setting limits on the number of Unix98 ptys allocated. | |
307 | * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. | |
308 | */ | |
309 | int pty_limit = NR_UNIX98_PTY_DEFAULT; | |
310 | static int pty_limit_min = 0; | |
311 | static int pty_limit_max = NR_UNIX98_PTY_MAX; | |
312 | ||
313 | ctl_table pty_table[] = { | |
314 | { | |
315 | .ctl_name = PTY_MAX, | |
316 | .procname = "max", | |
317 | .maxlen = sizeof(int), | |
318 | .mode = 0644, | |
319 | .data = &pty_limit, | |
320 | .proc_handler = &proc_dointvec_minmax, | |
321 | .strategy = &sysctl_intvec, | |
322 | .extra1 = &pty_limit_min, | |
323 | .extra2 = &pty_limit_max, | |
324 | }, { | |
325 | .ctl_name = PTY_NR, | |
326 | .procname = "nr", | |
327 | .maxlen = sizeof(int), | |
328 | .mode = 0444, | |
329 | .proc_handler = &proc_dointvec, | |
330 | }, { | |
331 | .ctl_name = 0 | |
332 | } | |
333 | }; | |
334 | ||
335 | static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file, | |
336 | unsigned int cmd, unsigned long arg) | |
337 | { | |
338 | switch (cmd) { | |
339 | case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ | |
340 | return pty_set_lock(tty, (int __user *)arg); | |
341 | case TIOCGPTN: /* Get PT Number */ | |
342 | return put_user(tty->index, (unsigned int __user *)arg); | |
343 | } | |
344 | ||
345 | return -ENOIOCTLCMD; | |
346 | } | |
347 | ||
348 | static void __init unix98_pty_init(void) | |
349 | { | |
1da177e4 LT |
350 | ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX); |
351 | if (!ptm_driver) | |
352 | panic("Couldn't allocate Unix98 ptm driver"); | |
353 | pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX); | |
354 | if (!pts_driver) | |
355 | panic("Couldn't allocate Unix98 pts driver"); | |
356 | ||
357 | ptm_driver->owner = THIS_MODULE; | |
358 | ptm_driver->driver_name = "pty_master"; | |
359 | ptm_driver->name = "ptm"; | |
360 | ptm_driver->major = UNIX98_PTY_MASTER_MAJOR; | |
361 | ptm_driver->minor_start = 0; | |
362 | ptm_driver->type = TTY_DRIVER_TYPE_PTY; | |
363 | ptm_driver->subtype = PTY_TYPE_MASTER; | |
364 | ptm_driver->init_termios = tty_std_termios; | |
365 | ptm_driver->init_termios.c_iflag = 0; | |
366 | ptm_driver->init_termios.c_oflag = 0; | |
367 | ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; | |
368 | ptm_driver->init_termios.c_lflag = 0; | |
369 | ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | | |
331b8319 | 370 | TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM; |
1da177e4 LT |
371 | ptm_driver->other = pts_driver; |
372 | tty_set_operations(ptm_driver, &pty_ops); | |
373 | ptm_driver->ioctl = pty_unix98_ioctl; | |
374 | ||
375 | pts_driver->owner = THIS_MODULE; | |
376 | pts_driver->driver_name = "pty_slave"; | |
377 | pts_driver->name = "pts"; | |
378 | pts_driver->major = UNIX98_PTY_SLAVE_MAJOR; | |
379 | pts_driver->minor_start = 0; | |
380 | pts_driver->type = TTY_DRIVER_TYPE_PTY; | |
381 | pts_driver->subtype = PTY_TYPE_SLAVE; | |
382 | pts_driver->init_termios = tty_std_termios; | |
383 | pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; | |
384 | pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | | |
331b8319 | 385 | TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM; |
1da177e4 LT |
386 | pts_driver->other = ptm_driver; |
387 | tty_set_operations(pts_driver, &pty_ops); | |
388 | ||
389 | if (tty_register_driver(ptm_driver)) | |
390 | panic("Couldn't register Unix98 ptm driver"); | |
391 | if (tty_register_driver(pts_driver)) | |
392 | panic("Couldn't register Unix98 pts driver"); | |
393 | ||
394 | pty_table[1].data = &ptm_driver->refcount; | |
395 | } | |
396 | #else | |
397 | static inline void unix98_pty_init(void) { } | |
398 | #endif | |
399 | ||
400 | static int __init pty_init(void) | |
401 | { | |
402 | legacy_pty_init(); | |
403 | unix98_pty_init(); | |
404 | return 0; | |
405 | } | |
406 | module_init(pty_init); |