Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/drivers/char/pty.c
Parent Directory
|
Revision Log
Revision 630 -
(show annotations)
(download)
Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 12027 byte(s)
Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 12027 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | |
14 | #include <linux/config.h> |
15 | #include <linux/module.h> /* For EXPORT_SYMBOL */ |
16 | |
17 | #include <linux/errno.h> |
18 | #include <linux/sched.h> |
19 | #include <linux/interrupt.h> |
20 | #include <linux/tty.h> |
21 | #include <linux/tty_flip.h> |
22 | #include <linux/fcntl.h> |
23 | #include <linux/string.h> |
24 | #include <linux/major.h> |
25 | #include <linux/mm.h> |
26 | #include <linux/init.h> |
27 | #include <linux/devfs_fs_kernel.h> |
28 | #include <linux/sysctl.h> |
29 | |
30 | #include <asm/uaccess.h> |
31 | #include <asm/system.h> |
32 | #include <linux/bitops.h> |
33 | #include <linux/devpts_fs.h> |
34 | |
35 | /* These are global because they are accessed in tty_io.c */ |
36 | #ifdef CONFIG_UNIX98_PTYS |
37 | struct tty_driver *ptm_driver; |
38 | static struct tty_driver *pts_driver; |
39 | #endif |
40 | |
41 | static void pty_close(struct tty_struct * tty, struct file * filp) |
42 | { |
43 | if (!tty) |
44 | return; |
45 | if (tty->driver->subtype == PTY_TYPE_MASTER) { |
46 | if (tty->count > 1) |
47 | printk("master pty_close: count = %d!!\n", tty->count); |
48 | } else { |
49 | if (tty->count > 2) |
50 | return; |
51 | } |
52 | wake_up_interruptible(&tty->read_wait); |
53 | wake_up_interruptible(&tty->write_wait); |
54 | tty->packet = 0; |
55 | if (!tty->link) |
56 | return; |
57 | tty->link->packet = 0; |
58 | set_bit(TTY_OTHER_CLOSED, &tty->link->flags); |
59 | wake_up_interruptible(&tty->link->read_wait); |
60 | wake_up_interruptible(&tty->link->write_wait); |
61 | if (tty->driver->subtype == PTY_TYPE_MASTER) { |
62 | set_bit(TTY_OTHER_CLOSED, &tty->flags); |
63 | #ifdef CONFIG_UNIX98_PTYS |
64 | if (tty->driver == ptm_driver) |
65 | devpts_pty_kill(tty->index); |
66 | #endif |
67 | tty_vhangup(tty->link); |
68 | } |
69 | } |
70 | |
71 | /* |
72 | * The unthrottle routine is called by the line discipline to signal |
73 | * that it can receive more characters. For PTY's, the TTY_THROTTLED |
74 | * flag is always set, to force the line discipline to always call the |
75 | * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE |
76 | * characters in the queue. This is necessary since each time this |
77 | * happens, we need to wake up any sleeping processes that could be |
78 | * (1) trying to send data to the pty, or (2) waiting in wait_until_sent() |
79 | * for the pty buffer to be drained. |
80 | */ |
81 | static void pty_unthrottle(struct tty_struct * tty) |
82 | { |
83 | struct tty_struct *o_tty = tty->link; |
84 | |
85 | if (!o_tty) |
86 | return; |
87 | |
88 | tty_wakeup(o_tty); |
89 | set_bit(TTY_THROTTLED, &tty->flags); |
90 | } |
91 | |
92 | /* |
93 | * WSH 05/24/97: modified to |
94 | * (1) use space in tty->flip instead of a shared temp buffer |
95 | * The flip buffers aren't being used for a pty, so there's lots |
96 | * of space available. The buffer is protected by a per-pty |
97 | * semaphore that should almost never come under contention. |
98 | * (2) avoid redundant copying for cases where count >> receive_room |
99 | * N.B. Calls from user space may now return an error code instead of |
100 | * a count. |
101 | * |
102 | * FIXME: Our pty_write method is called with our ldisc lock held but |
103 | * not our partners. We can't just take the other one blindly without |
104 | * risking deadlocks. There is also the small matter of TTY_DONT_FLIP |
105 | */ |
106 | static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count) |
107 | { |
108 | struct tty_struct *to = tty->link; |
109 | int c; |
110 | |
111 | if (!to || tty->stopped) |
112 | return 0; |
113 | |
114 | c = to->ldisc.receive_room(to); |
115 | if (c > count) |
116 | c = count; |
117 | to->ldisc.receive_buf(to, buf, NULL, c); |
118 | |
119 | return c; |
120 | } |
121 | |
122 | static int pty_write_room(struct tty_struct *tty) |
123 | { |
124 | struct tty_struct *to = tty->link; |
125 | |
126 | if (!to || tty->stopped) |
127 | return 0; |
128 | |
129 | return to->ldisc.receive_room(to); |
130 | } |
131 | |
132 | /* |
133 | * WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior |
134 | * The chars_in_buffer() value is used by the ldisc select() function |
135 | * to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256). |
136 | * The pty driver chars_in_buffer() Master/Slave must behave differently: |
137 | * |
138 | * The Master side needs to allow typed-ahead commands to accumulate |
139 | * while being canonicalized, so we report "our buffer" as empty until |
140 | * some threshold is reached, and then report the count. (Any count > |
141 | * WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock |
142 | * the count returned must be 0 if no canonical data is available to be |
143 | * read. (The N_TTY ldisc.chars_in_buffer now knows this.) |
144 | * |
145 | * The Slave side passes all characters in raw mode to the Master side's |
146 | * buffer where they can be read immediately, so in this case we can |
147 | * return the true count in the buffer. |
148 | */ |
149 | static int pty_chars_in_buffer(struct tty_struct *tty) |
150 | { |
151 | struct tty_struct *to = tty->link; |
152 | ssize_t (*chars_in_buffer)(struct tty_struct *); |
153 | int count; |
154 | |
155 | /* We should get the line discipline lock for "tty->link" */ |
156 | if (!to || !(chars_in_buffer = to->ldisc.chars_in_buffer)) |
157 | return 0; |
158 | |
159 | /* The ldisc must report 0 if no characters available to be read */ |
160 | count = chars_in_buffer(to); |
161 | |
162 | if (tty->driver->subtype == PTY_TYPE_SLAVE) return count; |
163 | |
164 | /* Master side driver ... if the other side's read buffer is less than |
165 | * half full, return 0 to allow writers to proceed; otherwise return |
166 | * the count. This leaves a comfortable margin to avoid overflow, |
167 | * and still allows half a buffer's worth of typed-ahead commands. |
168 | */ |
169 | return ((count < N_TTY_BUF_SIZE/2) ? 0 : count); |
170 | } |
171 | |
172 | /* Set the lock flag on a pty */ |
173 | static int pty_set_lock(struct tty_struct *tty, int __user * arg) |
174 | { |
175 | int val; |
176 | if (get_user(val,arg)) |
177 | return -EFAULT; |
178 | if (val) |
179 | set_bit(TTY_PTY_LOCK, &tty->flags); |
180 | else |
181 | clear_bit(TTY_PTY_LOCK, &tty->flags); |
182 | return 0; |
183 | } |
184 | |
185 | static void pty_flush_buffer(struct tty_struct *tty) |
186 | { |
187 | struct tty_struct *to = tty->link; |
188 | |
189 | if (!to) |
190 | return; |
191 | |
192 | if (to->ldisc.flush_buffer) |
193 | to->ldisc.flush_buffer(to); |
194 | |
195 | if (to->packet) { |
196 | tty->ctrl_status |= TIOCPKT_FLUSHWRITE; |
197 | wake_up_interruptible(&to->read_wait); |
198 | } |
199 | } |
200 | |
201 | static int pty_open(struct tty_struct *tty, struct file * filp) |
202 | { |
203 | int retval = -ENODEV; |
204 | |
205 | if (!tty || !tty->link) |
206 | goto out; |
207 | |
208 | retval = -EIO; |
209 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) |
210 | goto out; |
211 | if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) |
212 | goto out; |
213 | if (tty->link->count != 1) |
214 | goto out; |
215 | |
216 | clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); |
217 | set_bit(TTY_THROTTLED, &tty->flags); |
218 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
219 | retval = 0; |
220 | out: |
221 | return retval; |
222 | } |
223 | |
224 | static void pty_set_termios(struct tty_struct *tty, struct termios *old_termios) |
225 | { |
226 | tty->termios->c_cflag &= ~(CSIZE | PARENB); |
227 | tty->termios->c_cflag |= (CS8 | CREAD); |
228 | } |
229 | |
230 | static struct tty_operations pty_ops = { |
231 | .open = pty_open, |
232 | .close = pty_close, |
233 | .write = pty_write, |
234 | .write_room = pty_write_room, |
235 | .flush_buffer = pty_flush_buffer, |
236 | .chars_in_buffer = pty_chars_in_buffer, |
237 | .unthrottle = pty_unthrottle, |
238 | .set_termios = pty_set_termios, |
239 | }; |
240 | |
241 | /* Traditional BSD devices */ |
242 | #ifdef CONFIG_LEGACY_PTYS |
243 | static struct tty_driver *pty_driver, *pty_slave_driver; |
244 | |
245 | static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file, |
246 | unsigned int cmd, unsigned long arg) |
247 | { |
248 | switch (cmd) { |
249 | case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ |
250 | return pty_set_lock(tty, (int __user *) arg); |
251 | } |
252 | return -ENOIOCTLCMD; |
253 | } |
254 | |
255 | static void __init legacy_pty_init(void) |
256 | { |
257 | |
258 | pty_driver = alloc_tty_driver(NR_PTYS); |
259 | if (!pty_driver) |
260 | panic("Couldn't allocate pty driver"); |
261 | |
262 | pty_slave_driver = alloc_tty_driver(NR_PTYS); |
263 | if (!pty_slave_driver) |
264 | panic("Couldn't allocate pty slave driver"); |
265 | |
266 | pty_driver->owner = THIS_MODULE; |
267 | pty_driver->driver_name = "pty_master"; |
268 | pty_driver->name = "pty"; |
269 | pty_driver->devfs_name = "pty/m"; |
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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW; |
280 | pty_driver->other = pty_slave_driver; |
281 | tty_set_operations(pty_driver, &pty_ops); |
282 | pty_driver->ioctl = pty_bsd_ioctl; |
283 | |
284 | pty_slave_driver->owner = THIS_MODULE; |
285 | pty_slave_driver->driver_name = "pty_slave"; |
286 | pty_slave_driver->name = "ttyp"; |
287 | pty_slave_driver->devfs_name = "pty/s"; |
288 | pty_slave_driver->major = PTY_SLAVE_MAJOR; |
289 | pty_slave_driver->minor_start = 0; |
290 | pty_slave_driver->type = TTY_DRIVER_TYPE_PTY; |
291 | pty_slave_driver->subtype = PTY_TYPE_SLAVE; |
292 | pty_slave_driver->init_termios = tty_std_termios; |
293 | pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; |
294 | pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS | |
295 | TTY_DRIVER_REAL_RAW; |
296 | pty_slave_driver->other = pty_driver; |
297 | tty_set_operations(pty_slave_driver, &pty_ops); |
298 | |
299 | if (tty_register_driver(pty_driver)) |
300 | panic("Couldn't register pty driver"); |
301 | if (tty_register_driver(pty_slave_driver)) |
302 | panic("Couldn't register pty slave driver"); |
303 | } |
304 | #else |
305 | static inline void legacy_pty_init(void) { } |
306 | #endif |
307 | |
308 | /* Unix98 devices */ |
309 | #ifdef CONFIG_UNIX98_PTYS |
310 | /* |
311 | * sysctl support for setting limits on the number of Unix98 ptys allocated. |
312 | * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly. |
313 | */ |
314 | int pty_limit = NR_UNIX98_PTY_DEFAULT; |
315 | static int pty_limit_min = 0; |
316 | static int pty_limit_max = NR_UNIX98_PTY_MAX; |
317 | |
318 | ctl_table pty_table[] = { |
319 | { |
320 | .ctl_name = PTY_MAX, |
321 | .procname = "max", |
322 | .maxlen = sizeof(int), |
323 | .mode = 0644, |
324 | .data = &pty_limit, |
325 | .proc_handler = &proc_dointvec_minmax, |
326 | .strategy = &sysctl_intvec, |
327 | .extra1 = &pty_limit_min, |
328 | .extra2 = &pty_limit_max, |
329 | }, { |
330 | .ctl_name = PTY_NR, |
331 | .procname = "nr", |
332 | .maxlen = sizeof(int), |
333 | .mode = 0444, |
334 | .proc_handler = &proc_dointvec, |
335 | }, { |
336 | .ctl_name = 0 |
337 | } |
338 | }; |
339 | |
340 | static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file, |
341 | unsigned int cmd, unsigned long arg) |
342 | { |
343 | switch (cmd) { |
344 | case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ |
345 | return pty_set_lock(tty, (int __user *)arg); |
346 | case TIOCGPTN: /* Get PT Number */ |
347 | return put_user(tty->index, (unsigned int __user *)arg); |
348 | } |
349 | |
350 | return -ENOIOCTLCMD; |
351 | } |
352 | |
353 | static void __init unix98_pty_init(void) |
354 | { |
355 | devfs_mk_dir("pts"); |
356 | ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX); |
357 | if (!ptm_driver) |
358 | panic("Couldn't allocate Unix98 ptm driver"); |
359 | pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX); |
360 | if (!pts_driver) |
361 | panic("Couldn't allocate Unix98 pts driver"); |
362 | |
363 | ptm_driver->owner = THIS_MODULE; |
364 | ptm_driver->driver_name = "pty_master"; |
365 | ptm_driver->name = "ptm"; |
366 | ptm_driver->major = UNIX98_PTY_MASTER_MAJOR; |
367 | ptm_driver->minor_start = 0; |
368 | ptm_driver->type = TTY_DRIVER_TYPE_PTY; |
369 | ptm_driver->subtype = PTY_TYPE_MASTER; |
370 | ptm_driver->init_termios = tty_std_termios; |
371 | ptm_driver->init_termios.c_iflag = 0; |
372 | ptm_driver->init_termios.c_oflag = 0; |
373 | ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; |
374 | ptm_driver->init_termios.c_lflag = 0; |
375 | ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | |
376 | TTY_DRIVER_NO_DEVFS | TTY_DRIVER_DEVPTS_MEM; |
377 | ptm_driver->other = pts_driver; |
378 | tty_set_operations(ptm_driver, &pty_ops); |
379 | ptm_driver->ioctl = pty_unix98_ioctl; |
380 | |
381 | pts_driver->owner = THIS_MODULE; |
382 | pts_driver->driver_name = "pty_slave"; |
383 | pts_driver->name = "pts"; |
384 | pts_driver->major = UNIX98_PTY_SLAVE_MAJOR; |
385 | pts_driver->minor_start = 0; |
386 | pts_driver->type = TTY_DRIVER_TYPE_PTY; |
387 | pts_driver->subtype = PTY_TYPE_SLAVE; |
388 | pts_driver->init_termios = tty_std_termios; |
389 | pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; |
390 | pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | |
391 | TTY_DRIVER_NO_DEVFS | TTY_DRIVER_DEVPTS_MEM; |
392 | pts_driver->other = ptm_driver; |
393 | tty_set_operations(pts_driver, &pty_ops); |
394 | |
395 | if (tty_register_driver(ptm_driver)) |
396 | panic("Couldn't register Unix98 ptm driver"); |
397 | if (tty_register_driver(pts_driver)) |
398 | panic("Couldn't register Unix98 pts driver"); |
399 | |
400 | pty_table[1].data = &ptm_driver->refcount; |
401 | } |
402 | #else |
403 | static inline void unix98_pty_init(void) { } |
404 | #endif |
405 | |
406 | static int __init pty_init(void) |
407 | { |
408 | legacy_pty_init(); |
409 | unix98_pty_init(); |
410 | return 0; |
411 | } |
412 | module_init(pty_init); |