Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * n_tty.c --- implements the N_TTY line discipline. | |
4edf1827 | 3 | * |
1da177e4 LT |
4 | * This code used to be in tty_io.c, but things are getting hairy |
5 | * enough that it made sense to split things off. (The N_TTY | |
6 | * processing has changed so much that it's hardly recognizable, | |
7 | * anyway...) | |
8 | * | |
9 | * Note that the open routine for N_TTY is guaranteed never to return | |
10 | * an error. This is because Linux will fall back to setting a line | |
4edf1827 | 11 | * to N_TTY if it can not switch to any other line discipline. |
1da177e4 LT |
12 | * |
13 | * Written by Theodore Ts'o, Copyright 1994. | |
4edf1827 | 14 | * |
1da177e4 LT |
15 | * This file also contains code originally written by Linus Torvalds, |
16 | * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994. | |
4edf1827 | 17 | * |
1da177e4 LT |
18 | * This file may be redistributed under the terms of the GNU General Public |
19 | * License. | |
20 | * | |
21 | * Reduced memory usage for older ARM systems - Russell King. | |
22 | * | |
4edf1827 | 23 | * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of |
1da177e4 LT |
24 | * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu> |
25 | * who actually finally proved there really was a race. | |
26 | * | |
27 | * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to | |
28 | * waiting writing processes-Sapan Bhatia <sapan@corewars.org>. | |
11a96d18 | 29 | * Also fixed a bug in BLOCKING mode where n_tty_write returns |
1da177e4 LT |
30 | * EAGAIN |
31 | */ | |
32 | ||
33 | #include <linux/types.h> | |
34 | #include <linux/major.h> | |
35 | #include <linux/errno.h> | |
36 | #include <linux/signal.h> | |
37 | #include <linux/fcntl.h> | |
38 | #include <linux/sched.h> | |
39 | #include <linux/interrupt.h> | |
40 | #include <linux/tty.h> | |
41 | #include <linux/timer.h> | |
42 | #include <linux/ctype.h> | |
43 | #include <linux/mm.h> | |
44 | #include <linux/string.h> | |
45 | #include <linux/slab.h> | |
46 | #include <linux/poll.h> | |
47 | #include <linux/bitops.h> | |
522ed776 MT |
48 | #include <linux/audit.h> |
49 | #include <linux/file.h> | |
300a6204 | 50 | #include <linux/uaccess.h> |
572b9adb | 51 | #include <linux/module.h> |
1da177e4 | 52 | |
1da177e4 LT |
53 | |
54 | /* number of characters left in xmit buffer before select has we have room */ | |
55 | #define WAKEUP_CHARS 256 | |
56 | ||
57 | /* | |
58 | * This defines the low- and high-watermarks for throttling and | |
59 | * unthrottling the TTY driver. These watermarks are used for | |
60 | * controlling the space in the read buffer. | |
61 | */ | |
62 | #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */ | |
bbd20759 | 63 | #define TTY_THRESHOLD_UNTHROTTLE 128 |
1da177e4 | 64 | |
a88a69c9 JP |
65 | /* |
66 | * Special byte codes used in the echo buffer to represent operations | |
67 | * or special handling of characters. Bytes in the echo buffer that | |
68 | * are not part of such special blocks are treated as normal character | |
69 | * codes. | |
70 | */ | |
71 | #define ECHO_OP_START 0xff | |
72 | #define ECHO_OP_MOVE_BACK_COL 0x80 | |
73 | #define ECHO_OP_SET_CANON_COL 0x81 | |
74 | #define ECHO_OP_ERASE_TAB 0x82 | |
75 | ||
522ed776 MT |
76 | static inline int tty_put_user(struct tty_struct *tty, unsigned char x, |
77 | unsigned char __user *ptr) | |
78 | { | |
79 | tty_audit_add_data(tty, &x, 1); | |
80 | return put_user(x, ptr); | |
81 | } | |
82 | ||
55db4c64 LT |
83 | /** |
84 | * n_tty_set__room - receive space | |
85 | * @tty: terminal | |
86 | * | |
87 | * Called by the driver to find out how much data it is | |
88 | * permitted to feed to the line discipline without any being lost | |
89 | * and thus to manage flow control. Not serialized. Answers for the | |
90 | * "instant". | |
91 | */ | |
92 | ||
93 | static void n_tty_set_room(struct tty_struct *tty) | |
94 | { | |
090abf7b | 95 | int left; |
55db4c64 LT |
96 | int old_left; |
97 | ||
090abf7b JA |
98 | /* tty->read_cnt is not read locked ? */ |
99 | if (I_PARMRK(tty)) { | |
100 | /* Multiply read_cnt by 3, since each byte might take up to | |
101 | * three times as many spaces when PARMRK is set (depending on | |
102 | * its flags, e.g. parity error). */ | |
103 | left = N_TTY_BUF_SIZE - tty->read_cnt * 3 - 1; | |
104 | } else | |
105 | left = N_TTY_BUF_SIZE - tty->read_cnt - 1; | |
106 | ||
55db4c64 LT |
107 | /* |
108 | * If we are doing input canonicalization, and there are no | |
109 | * pending newlines, let characters through without limit, so | |
110 | * that erase characters will be handled. Other excess | |
111 | * characters will be beeped. | |
112 | */ | |
113 | if (left <= 0) | |
114 | left = tty->icanon && !tty->canon_data; | |
115 | old_left = tty->receive_room; | |
116 | tty->receive_room = left; | |
117 | ||
118 | /* Did this open up the receive buffer? We may need to flip */ | |
119 | if (left && !old_left) | |
120 | schedule_work(&tty->buf.work); | |
121 | } | |
122 | ||
33f0f88f | 123 | static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty) |
1da177e4 LT |
124 | { |
125 | if (tty->read_cnt < N_TTY_BUF_SIZE) { | |
126 | tty->read_buf[tty->read_head] = c; | |
127 | tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1); | |
128 | tty->read_cnt++; | |
129 | } | |
130 | } | |
131 | ||
17b82060 AC |
132 | /** |
133 | * put_tty_queue - add character to tty | |
134 | * @c: character | |
135 | * @tty: tty device | |
136 | * | |
137 | * Add a character to the tty read_buf queue. This is done under the | |
138 | * read_lock to serialize character addition and also to protect us | |
139 | * against parallel reads or flushes | |
140 | */ | |
141 | ||
33f0f88f | 142 | static void put_tty_queue(unsigned char c, struct tty_struct *tty) |
1da177e4 LT |
143 | { |
144 | unsigned long flags; | |
145 | /* | |
146 | * The problem of stomping on the buffers ends here. | |
147 | * Why didn't anyone see this one coming? --AJK | |
148 | */ | |
149 | spin_lock_irqsave(&tty->read_lock, flags); | |
150 | put_tty_queue_nolock(c, tty); | |
151 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
152 | } | |
153 | ||
154 | /** | |
155 | * check_unthrottle - allow new receive data | |
156 | * @tty; tty device | |
157 | * | |
17b82060 AC |
158 | * Check whether to call the driver unthrottle functions |
159 | * | |
70522e12 | 160 | * Can sleep, may be called under the atomic_read_lock mutex but |
1da177e4 LT |
161 | * this is not guaranteed. |
162 | */ | |
4edf1827 | 163 | static void check_unthrottle(struct tty_struct *tty) |
1da177e4 | 164 | { |
39c2e60f AC |
165 | if (tty->count) |
166 | tty_unthrottle(tty); | |
1da177e4 LT |
167 | } |
168 | ||
169 | /** | |
170 | * reset_buffer_flags - reset buffer state | |
171 | * @tty: terminal to reset | |
172 | * | |
4edf1827 | 173 | * Reset the read buffer counters, clear the flags, |
1da177e4 LT |
174 | * and make sure the driver is unthrottled. Called |
175 | * from n_tty_open() and n_tty_flush_buffer(). | |
17b82060 AC |
176 | * |
177 | * Locking: tty_read_lock for read fields. | |
1da177e4 | 178 | */ |
a88a69c9 | 179 | |
1da177e4 LT |
180 | static void reset_buffer_flags(struct tty_struct *tty) |
181 | { | |
182 | unsigned long flags; | |
183 | ||
184 | spin_lock_irqsave(&tty->read_lock, flags); | |
185 | tty->read_head = tty->read_tail = tty->read_cnt = 0; | |
186 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
a88a69c9 JP |
187 | |
188 | mutex_lock(&tty->echo_lock); | |
189 | tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0; | |
190 | mutex_unlock(&tty->echo_lock); | |
191 | ||
1da177e4 LT |
192 | tty->canon_head = tty->canon_data = tty->erasing = 0; |
193 | memset(&tty->read_flags, 0, sizeof tty->read_flags); | |
55db4c64 | 194 | n_tty_set_room(tty); |
1da177e4 LT |
195 | } |
196 | ||
197 | /** | |
198 | * n_tty_flush_buffer - clean input queue | |
199 | * @tty: terminal device | |
200 | * | |
201 | * Flush the input buffer. Called when the line discipline is | |
202 | * being closed, when the tty layer wants the buffer flushed (eg | |
203 | * at hangup) or when the N_TTY line discipline internally has to | |
204 | * clean the pending queue (for example some signals). | |
205 | * | |
17b82060 | 206 | * Locking: ctrl_lock, read_lock. |
1da177e4 | 207 | */ |
4edf1827 AC |
208 | |
209 | static void n_tty_flush_buffer(struct tty_struct *tty) | |
1da177e4 | 210 | { |
04f378b1 | 211 | unsigned long flags; |
1da177e4 LT |
212 | /* clear everything and unthrottle the driver */ |
213 | reset_buffer_flags(tty); | |
4edf1827 | 214 | |
1da177e4 LT |
215 | if (!tty->link) |
216 | return; | |
217 | ||
04f378b1 | 218 | spin_lock_irqsave(&tty->ctrl_lock, flags); |
1da177e4 LT |
219 | if (tty->link->packet) { |
220 | tty->ctrl_status |= TIOCPKT_FLUSHREAD; | |
221 | wake_up_interruptible(&tty->link->read_wait); | |
222 | } | |
04f378b1 | 223 | spin_unlock_irqrestore(&tty->ctrl_lock, flags); |
1da177e4 LT |
224 | } |
225 | ||
226 | /** | |
227 | * n_tty_chars_in_buffer - report available bytes | |
228 | * @tty: tty device | |
229 | * | |
230 | * Report the number of characters buffered to be delivered to user | |
4edf1827 | 231 | * at this instant in time. |
17b82060 AC |
232 | * |
233 | * Locking: read_lock | |
1da177e4 | 234 | */ |
4edf1827 | 235 | |
1da177e4 LT |
236 | static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) |
237 | { | |
238 | unsigned long flags; | |
239 | ssize_t n = 0; | |
240 | ||
241 | spin_lock_irqsave(&tty->read_lock, flags); | |
242 | if (!tty->icanon) { | |
243 | n = tty->read_cnt; | |
244 | } else if (tty->canon_data) { | |
245 | n = (tty->canon_head > tty->read_tail) ? | |
246 | tty->canon_head - tty->read_tail : | |
247 | tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail); | |
248 | } | |
249 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
250 | return n; | |
251 | } | |
252 | ||
253 | /** | |
254 | * is_utf8_continuation - utf8 multibyte check | |
255 | * @c: byte to check | |
256 | * | |
257 | * Returns true if the utf8 character 'c' is a multibyte continuation | |
258 | * character. We use this to correctly compute the on screen size | |
259 | * of the character when printing | |
260 | */ | |
4edf1827 | 261 | |
1da177e4 LT |
262 | static inline int is_utf8_continuation(unsigned char c) |
263 | { | |
264 | return (c & 0xc0) == 0x80; | |
265 | } | |
266 | ||
267 | /** | |
268 | * is_continuation - multibyte check | |
269 | * @c: byte to check | |
270 | * | |
271 | * Returns true if the utf8 character 'c' is a multibyte continuation | |
272 | * character and the terminal is in unicode mode. | |
273 | */ | |
4edf1827 | 274 | |
1da177e4 LT |
275 | static inline int is_continuation(unsigned char c, struct tty_struct *tty) |
276 | { | |
277 | return I_IUTF8(tty) && is_utf8_continuation(c); | |
278 | } | |
279 | ||
280 | /** | |
a88a69c9 | 281 | * do_output_char - output one character |
1da177e4 LT |
282 | * @c: character (or partial unicode symbol) |
283 | * @tty: terminal device | |
a88a69c9 | 284 | * @space: space available in tty driver write buffer |
1da177e4 | 285 | * |
a88a69c9 JP |
286 | * This is a helper function that handles one output character |
287 | * (including special characters like TAB, CR, LF, etc.), | |
ee5aa7b8 JP |
288 | * doing OPOST processing and putting the results in the |
289 | * tty driver's write buffer. | |
a88a69c9 JP |
290 | * |
291 | * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY | |
292 | * and NLDLY. They simply aren't relevant in the world today. | |
293 | * If you ever need them, add them here. | |
1da177e4 | 294 | * |
a88a69c9 JP |
295 | * Returns the number of bytes of buffer space used or -1 if |
296 | * no space left. | |
297 | * | |
298 | * Locking: should be called under the output_lock to protect | |
299 | * the column state and space left in the buffer | |
1da177e4 | 300 | */ |
4edf1827 | 301 | |
a88a69c9 | 302 | static int do_output_char(unsigned char c, struct tty_struct *tty, int space) |
1da177e4 | 303 | { |
a88a69c9 | 304 | int spaces; |
1da177e4 | 305 | |
1da177e4 LT |
306 | if (!space) |
307 | return -1; | |
300a6204 | 308 | |
a88a69c9 JP |
309 | switch (c) { |
310 | case '\n': | |
311 | if (O_ONLRET(tty)) | |
312 | tty->column = 0; | |
313 | if (O_ONLCR(tty)) { | |
314 | if (space < 2) | |
315 | return -1; | |
1da177e4 | 316 | tty->canon_column = tty->column = 0; |
37f81fa1 | 317 | tty->ops->write(tty, "\r\n", 2); |
a88a69c9 JP |
318 | return 2; |
319 | } | |
320 | tty->canon_column = tty->column; | |
321 | break; | |
322 | case '\r': | |
323 | if (O_ONOCR(tty) && tty->column == 0) | |
324 | return 0; | |
325 | if (O_OCRNL(tty)) { | |
326 | c = '\n'; | |
327 | if (O_ONLRET(tty)) | |
328 | tty->canon_column = tty->column = 0; | |
1da177e4 | 329 | break; |
a88a69c9 JP |
330 | } |
331 | tty->canon_column = tty->column = 0; | |
332 | break; | |
333 | case '\t': | |
334 | spaces = 8 - (tty->column & 7); | |
335 | if (O_TABDLY(tty) == XTABS) { | |
336 | if (space < spaces) | |
337 | return -1; | |
1da177e4 | 338 | tty->column += spaces; |
a88a69c9 JP |
339 | tty->ops->write(tty, " ", spaces); |
340 | return spaces; | |
1da177e4 | 341 | } |
a88a69c9 JP |
342 | tty->column += spaces; |
343 | break; | |
344 | case '\b': | |
345 | if (tty->column > 0) | |
346 | tty->column--; | |
347 | break; | |
348 | default: | |
a59c0d6f JP |
349 | if (!iscntrl(c)) { |
350 | if (O_OLCUC(tty)) | |
351 | c = toupper(c); | |
352 | if (!is_continuation(c, tty)) | |
353 | tty->column++; | |
354 | } | |
a88a69c9 | 355 | break; |
1da177e4 | 356 | } |
a88a69c9 | 357 | |
f34d7a5b | 358 | tty_put_char(tty, c); |
a88a69c9 JP |
359 | return 1; |
360 | } | |
361 | ||
362 | /** | |
363 | * process_output - output post processor | |
364 | * @c: character (or partial unicode symbol) | |
365 | * @tty: terminal device | |
366 | * | |
ee5aa7b8 JP |
367 | * Output one character with OPOST processing. |
368 | * Returns -1 when the output device is full and the character | |
369 | * must be retried. | |
a88a69c9 JP |
370 | * |
371 | * Locking: output_lock to protect column state and space left | |
372 | * (also, this is called from n_tty_write under the | |
373 | * tty layer write lock) | |
374 | */ | |
375 | ||
376 | static int process_output(unsigned char c, struct tty_struct *tty) | |
377 | { | |
378 | int space, retval; | |
379 | ||
380 | mutex_lock(&tty->output_lock); | |
381 | ||
382 | space = tty_write_room(tty); | |
383 | retval = do_output_char(c, tty, space); | |
384 | ||
385 | mutex_unlock(&tty->output_lock); | |
386 | if (retval < 0) | |
387 | return -1; | |
388 | else | |
389 | return 0; | |
1da177e4 LT |
390 | } |
391 | ||
392 | /** | |
a88a69c9 | 393 | * process_output_block - block post processor |
1da177e4 | 394 | * @tty: terminal device |
ee5aa7b8 JP |
395 | * @buf: character buffer |
396 | * @nr: number of bytes to output | |
397 | * | |
398 | * Output a block of characters with OPOST processing. | |
399 | * Returns the number of characters output. | |
1da177e4 LT |
400 | * |
401 | * This path is used to speed up block console writes, among other | |
402 | * things when processing blocks of output data. It handles only | |
403 | * the simple cases normally found and helps to generate blocks of | |
404 | * symbols for the console driver and thus improve performance. | |
405 | * | |
a88a69c9 JP |
406 | * Locking: output_lock to protect column state and space left |
407 | * (also, this is called from n_tty_write under the | |
408 | * tty layer write lock) | |
1da177e4 | 409 | */ |
4edf1827 | 410 | |
a88a69c9 JP |
411 | static ssize_t process_output_block(struct tty_struct *tty, |
412 | const unsigned char *buf, unsigned int nr) | |
1da177e4 LT |
413 | { |
414 | int space; | |
bbd20759 | 415 | int i; |
1da177e4 LT |
416 | const unsigned char *cp; |
417 | ||
a88a69c9 JP |
418 | mutex_lock(&tty->output_lock); |
419 | ||
f34d7a5b | 420 | space = tty_write_room(tty); |
300a6204 | 421 | if (!space) { |
a88a69c9 | 422 | mutex_unlock(&tty->output_lock); |
1da177e4 | 423 | return 0; |
a88a69c9 | 424 | } |
1da177e4 LT |
425 | if (nr > space) |
426 | nr = space; | |
427 | ||
428 | for (i = 0, cp = buf; i < nr; i++, cp++) { | |
a59c0d6f JP |
429 | unsigned char c = *cp; |
430 | ||
431 | switch (c) { | |
1da177e4 LT |
432 | case '\n': |
433 | if (O_ONLRET(tty)) | |
434 | tty->column = 0; | |
435 | if (O_ONLCR(tty)) | |
436 | goto break_out; | |
437 | tty->canon_column = tty->column; | |
438 | break; | |
439 | case '\r': | |
440 | if (O_ONOCR(tty) && tty->column == 0) | |
441 | goto break_out; | |
442 | if (O_OCRNL(tty)) | |
443 | goto break_out; | |
444 | tty->canon_column = tty->column = 0; | |
445 | break; | |
446 | case '\t': | |
447 | goto break_out; | |
448 | case '\b': | |
449 | if (tty->column > 0) | |
450 | tty->column--; | |
451 | break; | |
452 | default: | |
a59c0d6f JP |
453 | if (!iscntrl(c)) { |
454 | if (O_OLCUC(tty)) | |
455 | goto break_out; | |
456 | if (!is_continuation(c, tty)) | |
457 | tty->column++; | |
458 | } | |
1da177e4 LT |
459 | break; |
460 | } | |
461 | } | |
462 | break_out: | |
f34d7a5b | 463 | i = tty->ops->write(tty, buf, i); |
a88a69c9 JP |
464 | |
465 | mutex_unlock(&tty->output_lock); | |
1da177e4 LT |
466 | return i; |
467 | } | |
468 | ||
a88a69c9 JP |
469 | /** |
470 | * process_echoes - write pending echo characters | |
471 | * @tty: terminal device | |
472 | * | |
473 | * Write previously buffered echo (and other ldisc-generated) | |
474 | * characters to the tty. | |
475 | * | |
476 | * Characters generated by the ldisc (including echoes) need to | |
477 | * be buffered because the driver's write buffer can fill during | |
478 | * heavy program output. Echoing straight to the driver will | |
479 | * often fail under these conditions, causing lost characters and | |
480 | * resulting mismatches of ldisc state information. | |
481 | * | |
482 | * Since the ldisc state must represent the characters actually sent | |
483 | * to the driver at the time of the write, operations like certain | |
484 | * changes in column state are also saved in the buffer and executed | |
485 | * here. | |
486 | * | |
487 | * A circular fifo buffer is used so that the most recent characters | |
488 | * are prioritized. Also, when control characters are echoed with a | |
489 | * prefixed "^", the pair is treated atomically and thus not separated. | |
490 | * | |
491 | * Locking: output_lock to protect column state and space left, | |
492 | * echo_lock to protect the echo buffer | |
493 | */ | |
494 | ||
495 | static void process_echoes(struct tty_struct *tty) | |
496 | { | |
497 | int space, nr; | |
498 | unsigned char c; | |
499 | unsigned char *cp, *buf_end; | |
500 | ||
501 | if (!tty->echo_cnt) | |
502 | return; | |
503 | ||
504 | mutex_lock(&tty->output_lock); | |
505 | mutex_lock(&tty->echo_lock); | |
506 | ||
507 | space = tty_write_room(tty); | |
508 | ||
509 | buf_end = tty->echo_buf + N_TTY_BUF_SIZE; | |
510 | cp = tty->echo_buf + tty->echo_pos; | |
511 | nr = tty->echo_cnt; | |
512 | while (nr > 0) { | |
513 | c = *cp; | |
514 | if (c == ECHO_OP_START) { | |
515 | unsigned char op; | |
516 | unsigned char *opp; | |
517 | int no_space_left = 0; | |
518 | ||
519 | /* | |
520 | * If the buffer byte is the start of a multi-byte | |
521 | * operation, get the next byte, which is either the | |
522 | * op code or a control character value. | |
523 | */ | |
524 | opp = cp + 1; | |
525 | if (opp == buf_end) | |
526 | opp -= N_TTY_BUF_SIZE; | |
527 | op = *opp; | |
300a6204 | 528 | |
a88a69c9 JP |
529 | switch (op) { |
530 | unsigned int num_chars, num_bs; | |
531 | ||
532 | case ECHO_OP_ERASE_TAB: | |
533 | if (++opp == buf_end) | |
534 | opp -= N_TTY_BUF_SIZE; | |
535 | num_chars = *opp; | |
536 | ||
537 | /* | |
538 | * Determine how many columns to go back | |
539 | * in order to erase the tab. | |
540 | * This depends on the number of columns | |
541 | * used by other characters within the tab | |
542 | * area. If this (modulo 8) count is from | |
543 | * the start of input rather than from a | |
544 | * previous tab, we offset by canon column. | |
545 | * Otherwise, tab spacing is normal. | |
546 | */ | |
547 | if (!(num_chars & 0x80)) | |
548 | num_chars += tty->canon_column; | |
549 | num_bs = 8 - (num_chars & 7); | |
550 | ||
551 | if (num_bs > space) { | |
552 | no_space_left = 1; | |
553 | break; | |
554 | } | |
555 | space -= num_bs; | |
556 | while (num_bs--) { | |
557 | tty_put_char(tty, '\b'); | |
558 | if (tty->column > 0) | |
559 | tty->column--; | |
560 | } | |
561 | cp += 3; | |
562 | nr -= 3; | |
563 | break; | |
564 | ||
565 | case ECHO_OP_SET_CANON_COL: | |
566 | tty->canon_column = tty->column; | |
567 | cp += 2; | |
568 | nr -= 2; | |
569 | break; | |
570 | ||
571 | case ECHO_OP_MOVE_BACK_COL: | |
572 | if (tty->column > 0) | |
573 | tty->column--; | |
574 | cp += 2; | |
575 | nr -= 2; | |
576 | break; | |
577 | ||
578 | case ECHO_OP_START: | |
579 | /* This is an escaped echo op start code */ | |
580 | if (!space) { | |
581 | no_space_left = 1; | |
582 | break; | |
583 | } | |
584 | tty_put_char(tty, ECHO_OP_START); | |
585 | tty->column++; | |
586 | space--; | |
587 | cp += 2; | |
588 | nr -= 2; | |
589 | break; | |
590 | ||
591 | default: | |
a88a69c9 | 592 | /* |
62b26358 JP |
593 | * If the op is not a special byte code, |
594 | * it is a ctrl char tagged to be echoed | |
595 | * as "^X" (where X is the letter | |
596 | * representing the control char). | |
597 | * Note that we must ensure there is | |
598 | * enough space for the whole ctrl pair. | |
599 | * | |
a88a69c9 | 600 | */ |
62b26358 JP |
601 | if (space < 2) { |
602 | no_space_left = 1; | |
603 | break; | |
604 | } | |
605 | tty_put_char(tty, '^'); | |
606 | tty_put_char(tty, op ^ 0100); | |
607 | tty->column += 2; | |
608 | space -= 2; | |
a88a69c9 JP |
609 | cp += 2; |
610 | nr -= 2; | |
611 | } | |
612 | ||
613 | if (no_space_left) | |
614 | break; | |
615 | } else { | |
ee5aa7b8 JP |
616 | if (O_OPOST(tty) && |
617 | !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) { | |
618 | int retval = do_output_char(c, tty, space); | |
619 | if (retval < 0) | |
620 | break; | |
621 | space -= retval; | |
622 | } else { | |
623 | if (!space) | |
624 | break; | |
625 | tty_put_char(tty, c); | |
626 | space -= 1; | |
627 | } | |
a88a69c9 JP |
628 | cp += 1; |
629 | nr -= 1; | |
630 | } | |
631 | ||
632 | /* When end of circular buffer reached, wrap around */ | |
633 | if (cp >= buf_end) | |
634 | cp -= N_TTY_BUF_SIZE; | |
635 | } | |
636 | ||
637 | if (nr == 0) { | |
638 | tty->echo_pos = 0; | |
639 | tty->echo_cnt = 0; | |
640 | tty->echo_overrun = 0; | |
641 | } else { | |
642 | int num_processed = tty->echo_cnt - nr; | |
643 | tty->echo_pos += num_processed; | |
644 | tty->echo_pos &= N_TTY_BUF_SIZE - 1; | |
645 | tty->echo_cnt = nr; | |
646 | if (num_processed > 0) | |
647 | tty->echo_overrun = 0; | |
648 | } | |
649 | ||
650 | mutex_unlock(&tty->echo_lock); | |
651 | mutex_unlock(&tty->output_lock); | |
652 | ||
653 | if (tty->ops->flush_chars) | |
654 | tty->ops->flush_chars(tty); | |
655 | } | |
656 | ||
657 | /** | |
658 | * add_echo_byte - add a byte to the echo buffer | |
659 | * @c: unicode byte to echo | |
660 | * @tty: terminal device | |
661 | * | |
662 | * Add a character or operation byte to the echo buffer. | |
663 | * | |
664 | * Should be called under the echo lock to protect the echo buffer. | |
665 | */ | |
666 | ||
667 | static void add_echo_byte(unsigned char c, struct tty_struct *tty) | |
668 | { | |
669 | int new_byte_pos; | |
670 | ||
671 | if (tty->echo_cnt == N_TTY_BUF_SIZE) { | |
672 | /* Circular buffer is already at capacity */ | |
673 | new_byte_pos = tty->echo_pos; | |
674 | ||
675 | /* | |
676 | * Since the buffer start position needs to be advanced, | |
677 | * be sure to step by a whole operation byte group. | |
678 | */ | |
300a6204 | 679 | if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) { |
a88a69c9 JP |
680 | if (tty->echo_buf[(tty->echo_pos + 1) & |
681 | (N_TTY_BUF_SIZE - 1)] == | |
682 | ECHO_OP_ERASE_TAB) { | |
683 | tty->echo_pos += 3; | |
684 | tty->echo_cnt -= 2; | |
685 | } else { | |
686 | tty->echo_pos += 2; | |
687 | tty->echo_cnt -= 1; | |
688 | } | |
689 | } else { | |
690 | tty->echo_pos++; | |
691 | } | |
692 | tty->echo_pos &= N_TTY_BUF_SIZE - 1; | |
693 | ||
694 | tty->echo_overrun = 1; | |
695 | } else { | |
696 | new_byte_pos = tty->echo_pos + tty->echo_cnt; | |
697 | new_byte_pos &= N_TTY_BUF_SIZE - 1; | |
698 | tty->echo_cnt++; | |
699 | } | |
700 | ||
701 | tty->echo_buf[new_byte_pos] = c; | |
702 | } | |
703 | ||
704 | /** | |
705 | * echo_move_back_col - add operation to move back a column | |
706 | * @tty: terminal device | |
707 | * | |
708 | * Add an operation to the echo buffer to move back one column. | |
709 | * | |
710 | * Locking: echo_lock to protect the echo buffer | |
711 | */ | |
712 | ||
713 | static void echo_move_back_col(struct tty_struct *tty) | |
714 | { | |
715 | mutex_lock(&tty->echo_lock); | |
716 | ||
717 | add_echo_byte(ECHO_OP_START, tty); | |
718 | add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty); | |
719 | ||
720 | mutex_unlock(&tty->echo_lock); | |
721 | } | |
722 | ||
723 | /** | |
724 | * echo_set_canon_col - add operation to set the canon column | |
725 | * @tty: terminal device | |
726 | * | |
727 | * Add an operation to the echo buffer to set the canon column | |
728 | * to the current column. | |
729 | * | |
730 | * Locking: echo_lock to protect the echo buffer | |
731 | */ | |
732 | ||
733 | static void echo_set_canon_col(struct tty_struct *tty) | |
734 | { | |
735 | mutex_lock(&tty->echo_lock); | |
736 | ||
737 | add_echo_byte(ECHO_OP_START, tty); | |
738 | add_echo_byte(ECHO_OP_SET_CANON_COL, tty); | |
739 | ||
740 | mutex_unlock(&tty->echo_lock); | |
741 | } | |
742 | ||
743 | /** | |
744 | * echo_erase_tab - add operation to erase a tab | |
745 | * @num_chars: number of character columns already used | |
746 | * @after_tab: true if num_chars starts after a previous tab | |
747 | * @tty: terminal device | |
748 | * | |
749 | * Add an operation to the echo buffer to erase a tab. | |
750 | * | |
751 | * Called by the eraser function, which knows how many character | |
752 | * columns have been used since either a previous tab or the start | |
753 | * of input. This information will be used later, along with | |
754 | * canon column (if applicable), to go back the correct number | |
755 | * of columns. | |
756 | * | |
757 | * Locking: echo_lock to protect the echo buffer | |
758 | */ | |
759 | ||
760 | static void echo_erase_tab(unsigned int num_chars, int after_tab, | |
761 | struct tty_struct *tty) | |
762 | { | |
763 | mutex_lock(&tty->echo_lock); | |
764 | ||
765 | add_echo_byte(ECHO_OP_START, tty); | |
766 | add_echo_byte(ECHO_OP_ERASE_TAB, tty); | |
767 | ||
768 | /* We only need to know this modulo 8 (tab spacing) */ | |
769 | num_chars &= 7; | |
770 | ||
771 | /* Set the high bit as a flag if num_chars is after a previous tab */ | |
772 | if (after_tab) | |
773 | num_chars |= 0x80; | |
300a6204 | 774 | |
a88a69c9 JP |
775 | add_echo_byte(num_chars, tty); |
776 | ||
777 | mutex_unlock(&tty->echo_lock); | |
778 | } | |
779 | ||
780 | /** | |
781 | * echo_char_raw - echo a character raw | |
782 | * @c: unicode byte to echo | |
783 | * @tty: terminal device | |
784 | * | |
785 | * Echo user input back onto the screen. This must be called only when | |
786 | * L_ECHO(tty) is true. Called from the driver receive_buf path. | |
787 | * | |
788 | * This variant does not treat control characters specially. | |
789 | * | |
790 | * Locking: echo_lock to protect the echo buffer | |
791 | */ | |
792 | ||
793 | static void echo_char_raw(unsigned char c, struct tty_struct *tty) | |
794 | { | |
795 | mutex_lock(&tty->echo_lock); | |
796 | ||
797 | if (c == ECHO_OP_START) { | |
798 | add_echo_byte(ECHO_OP_START, tty); | |
799 | add_echo_byte(ECHO_OP_START, tty); | |
800 | } else { | |
801 | add_echo_byte(c, tty); | |
802 | } | |
803 | ||
804 | mutex_unlock(&tty->echo_lock); | |
805 | } | |
1da177e4 | 806 | |
1da177e4 | 807 | /** |
a88a69c9 | 808 | * echo_char - echo a character |
1da177e4 LT |
809 | * @c: unicode byte to echo |
810 | * @tty: terminal device | |
811 | * | |
4edf1827 | 812 | * Echo user input back onto the screen. This must be called only when |
1da177e4 | 813 | * L_ECHO(tty) is true. Called from the driver receive_buf path. |
17b82060 | 814 | * |
62b26358 JP |
815 | * This variant tags control characters to be echoed as "^X" |
816 | * (where X is the letter representing the control char). | |
a88a69c9 JP |
817 | * |
818 | * Locking: echo_lock to protect the echo buffer | |
1da177e4 LT |
819 | */ |
820 | ||
821 | static void echo_char(unsigned char c, struct tty_struct *tty) | |
822 | { | |
a88a69c9 JP |
823 | mutex_lock(&tty->echo_lock); |
824 | ||
825 | if (c == ECHO_OP_START) { | |
826 | add_echo_byte(ECHO_OP_START, tty); | |
827 | add_echo_byte(ECHO_OP_START, tty); | |
828 | } else { | |
62b26358 | 829 | if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') |
a88a69c9 JP |
830 | add_echo_byte(ECHO_OP_START, tty); |
831 | add_echo_byte(c, tty); | |
832 | } | |
833 | ||
834 | mutex_unlock(&tty->echo_lock); | |
1da177e4 LT |
835 | } |
836 | ||
17b82060 | 837 | /** |
a88a69c9 | 838 | * finish_erasing - complete erase |
17b82060 | 839 | * @tty: tty doing the erase |
17b82060 | 840 | */ |
a88a69c9 | 841 | |
1da177e4 LT |
842 | static inline void finish_erasing(struct tty_struct *tty) |
843 | { | |
844 | if (tty->erasing) { | |
a88a69c9 | 845 | echo_char_raw('/', tty); |
1da177e4 LT |
846 | tty->erasing = 0; |
847 | } | |
848 | } | |
849 | ||
850 | /** | |
851 | * eraser - handle erase function | |
852 | * @c: character input | |
853 | * @tty: terminal device | |
854 | * | |
3a4fa0a2 | 855 | * Perform erase and necessary output when an erase character is |
1da177e4 LT |
856 | * present in the stream from the driver layer. Handles the complexities |
857 | * of UTF-8 multibyte symbols. | |
17b82060 | 858 | * |
a88a69c9 | 859 | * Locking: read_lock for tty buffers |
1da177e4 | 860 | */ |
4edf1827 | 861 | |
1da177e4 LT |
862 | static void eraser(unsigned char c, struct tty_struct *tty) |
863 | { | |
864 | enum { ERASE, WERASE, KILL } kill_type; | |
865 | int head, seen_alnums, cnt; | |
866 | unsigned long flags; | |
867 | ||
17b82060 | 868 | /* FIXME: locking needed ? */ |
1da177e4 | 869 | if (tty->read_head == tty->canon_head) { |
7e94b1d9 | 870 | /* process_output('\a', tty); */ /* what do you think? */ |
1da177e4 LT |
871 | return; |
872 | } | |
873 | if (c == ERASE_CHAR(tty)) | |
874 | kill_type = ERASE; | |
875 | else if (c == WERASE_CHAR(tty)) | |
876 | kill_type = WERASE; | |
877 | else { | |
878 | if (!L_ECHO(tty)) { | |
879 | spin_lock_irqsave(&tty->read_lock, flags); | |
880 | tty->read_cnt -= ((tty->read_head - tty->canon_head) & | |
881 | (N_TTY_BUF_SIZE - 1)); | |
882 | tty->read_head = tty->canon_head; | |
883 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
884 | return; | |
885 | } | |
886 | if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { | |
887 | spin_lock_irqsave(&tty->read_lock, flags); | |
888 | tty->read_cnt -= ((tty->read_head - tty->canon_head) & | |
889 | (N_TTY_BUF_SIZE - 1)); | |
890 | tty->read_head = tty->canon_head; | |
891 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
892 | finish_erasing(tty); | |
893 | echo_char(KILL_CHAR(tty), tty); | |
894 | /* Add a newline if ECHOK is on and ECHOKE is off. */ | |
895 | if (L_ECHOK(tty)) | |
a88a69c9 | 896 | echo_char_raw('\n', tty); |
1da177e4 LT |
897 | return; |
898 | } | |
899 | kill_type = KILL; | |
900 | } | |
901 | ||
902 | seen_alnums = 0; | |
17b82060 | 903 | /* FIXME: Locking ?? */ |
1da177e4 LT |
904 | while (tty->read_head != tty->canon_head) { |
905 | head = tty->read_head; | |
906 | ||
907 | /* erase a single possibly multibyte character */ | |
908 | do { | |
909 | head = (head - 1) & (N_TTY_BUF_SIZE-1); | |
910 | c = tty->read_buf[head]; | |
911 | } while (is_continuation(c, tty) && head != tty->canon_head); | |
912 | ||
913 | /* do not partially erase */ | |
914 | if (is_continuation(c, tty)) | |
915 | break; | |
916 | ||
917 | if (kill_type == WERASE) { | |
918 | /* Equivalent to BSD's ALTWERASE. */ | |
919 | if (isalnum(c) || c == '_') | |
920 | seen_alnums++; | |
921 | else if (seen_alnums) | |
922 | break; | |
923 | } | |
924 | cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1); | |
925 | spin_lock_irqsave(&tty->read_lock, flags); | |
926 | tty->read_head = head; | |
927 | tty->read_cnt -= cnt; | |
928 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
929 | if (L_ECHO(tty)) { | |
930 | if (L_ECHOPRT(tty)) { | |
931 | if (!tty->erasing) { | |
a88a69c9 | 932 | echo_char_raw('\\', tty); |
1da177e4 LT |
933 | tty->erasing = 1; |
934 | } | |
935 | /* if cnt > 1, output a multi-byte character */ | |
936 | echo_char(c, tty); | |
937 | while (--cnt > 0) { | |
938 | head = (head+1) & (N_TTY_BUF_SIZE-1); | |
a88a69c9 JP |
939 | echo_char_raw(tty->read_buf[head], tty); |
940 | echo_move_back_col(tty); | |
1da177e4 LT |
941 | } |
942 | } else if (kill_type == ERASE && !L_ECHOE(tty)) { | |
943 | echo_char(ERASE_CHAR(tty), tty); | |
944 | } else if (c == '\t') { | |
a88a69c9 JP |
945 | unsigned int num_chars = 0; |
946 | int after_tab = 0; | |
947 | unsigned long tail = tty->read_head; | |
948 | ||
949 | /* | |
950 | * Count the columns used for characters | |
951 | * since the start of input or after a | |
952 | * previous tab. | |
953 | * This info is used to go back the correct | |
954 | * number of columns. | |
955 | */ | |
956 | while (tail != tty->canon_head) { | |
957 | tail = (tail-1) & (N_TTY_BUF_SIZE-1); | |
1da177e4 | 958 | c = tty->read_buf[tail]; |
a88a69c9 JP |
959 | if (c == '\t') { |
960 | after_tab = 1; | |
961 | break; | |
300a6204 | 962 | } else if (iscntrl(c)) { |
1da177e4 | 963 | if (L_ECHOCTL(tty)) |
a88a69c9 JP |
964 | num_chars += 2; |
965 | } else if (!is_continuation(c, tty)) { | |
966 | num_chars++; | |
967 | } | |
1da177e4 | 968 | } |
a88a69c9 | 969 | echo_erase_tab(num_chars, after_tab, tty); |
1da177e4 LT |
970 | } else { |
971 | if (iscntrl(c) && L_ECHOCTL(tty)) { | |
a88a69c9 JP |
972 | echo_char_raw('\b', tty); |
973 | echo_char_raw(' ', tty); | |
974 | echo_char_raw('\b', tty); | |
1da177e4 LT |
975 | } |
976 | if (!iscntrl(c) || L_ECHOCTL(tty)) { | |
a88a69c9 JP |
977 | echo_char_raw('\b', tty); |
978 | echo_char_raw(' ', tty); | |
979 | echo_char_raw('\b', tty); | |
1da177e4 LT |
980 | } |
981 | } | |
982 | } | |
983 | if (kill_type == ERASE) | |
984 | break; | |
985 | } | |
a88a69c9 | 986 | if (tty->read_head == tty->canon_head && L_ECHO(tty)) |
1da177e4 LT |
987 | finish_erasing(tty); |
988 | } | |
989 | ||
990 | /** | |
991 | * isig - handle the ISIG optio | |
992 | * @sig: signal | |
993 | * @tty: terminal | |
994 | * @flush: force flush | |
995 | * | |
996 | * Called when a signal is being sent due to terminal input. This | |
997 | * may caus terminal flushing to take place according to the termios | |
998 | * settings and character used. Called from the driver receive_buf | |
999 | * path so serialized. | |
17b82060 AC |
1000 | * |
1001 | * Locking: ctrl_lock, read_lock (both via flush buffer) | |
1da177e4 | 1002 | */ |
4edf1827 | 1003 | |
1da177e4 LT |
1004 | static inline void isig(int sig, struct tty_struct *tty, int flush) |
1005 | { | |
ab521dc0 EB |
1006 | if (tty->pgrp) |
1007 | kill_pgrp(tty->pgrp, sig, 1); | |
1da177e4 LT |
1008 | if (flush || !L_NOFLSH(tty)) { |
1009 | n_tty_flush_buffer(tty); | |
f34d7a5b | 1010 | tty_driver_flush_buffer(tty); |
1da177e4 LT |
1011 | } |
1012 | } | |
1013 | ||
1014 | /** | |
1015 | * n_tty_receive_break - handle break | |
1016 | * @tty: terminal | |
1017 | * | |
1018 | * An RS232 break event has been hit in the incoming bitstream. This | |
1019 | * can cause a variety of events depending upon the termios settings. | |
1020 | * | |
1021 | * Called from the receive_buf path so single threaded. | |
1022 | */ | |
4edf1827 | 1023 | |
1da177e4 LT |
1024 | static inline void n_tty_receive_break(struct tty_struct *tty) |
1025 | { | |
1026 | if (I_IGNBRK(tty)) | |
1027 | return; | |
1028 | if (I_BRKINT(tty)) { | |
1029 | isig(SIGINT, tty, 1); | |
1030 | return; | |
1031 | } | |
1032 | if (I_PARMRK(tty)) { | |
1033 | put_tty_queue('\377', tty); | |
1034 | put_tty_queue('\0', tty); | |
1035 | } | |
1036 | put_tty_queue('\0', tty); | |
1037 | wake_up_interruptible(&tty->read_wait); | |
1038 | } | |
1039 | ||
1040 | /** | |
1041 | * n_tty_receive_overrun - handle overrun reporting | |
1042 | * @tty: terminal | |
1043 | * | |
1044 | * Data arrived faster than we could process it. While the tty | |
1045 | * driver has flagged this the bits that were missed are gone | |
1046 | * forever. | |
1047 | * | |
1048 | * Called from the receive_buf path so single threaded. Does not | |
1049 | * need locking as num_overrun and overrun_time are function | |
1050 | * private. | |
1051 | */ | |
4edf1827 | 1052 | |
1da177e4 LT |
1053 | static inline void n_tty_receive_overrun(struct tty_struct *tty) |
1054 | { | |
1055 | char buf[64]; | |
1056 | ||
1057 | tty->num_overrun++; | |
1058 | if (time_before(tty->overrun_time, jiffies - HZ) || | |
1059 | time_after(tty->overrun_time, jiffies)) { | |
1060 | printk(KERN_WARNING "%s: %d input overrun(s)\n", | |
1061 | tty_name(tty, buf), | |
1062 | tty->num_overrun); | |
1063 | tty->overrun_time = jiffies; | |
1064 | tty->num_overrun = 0; | |
1065 | } | |
1066 | } | |
1067 | ||
1068 | /** | |
1069 | * n_tty_receive_parity_error - error notifier | |
1070 | * @tty: terminal device | |
1071 | * @c: character | |
1072 | * | |
1073 | * Process a parity error and queue the right data to indicate | |
3a4fa0a2 | 1074 | * the error case if necessary. Locking as per n_tty_receive_buf. |
1da177e4 LT |
1075 | */ |
1076 | static inline void n_tty_receive_parity_error(struct tty_struct *tty, | |
1077 | unsigned char c) | |
1078 | { | |
4edf1827 | 1079 | if (I_IGNPAR(tty)) |
1da177e4 | 1080 | return; |
1da177e4 LT |
1081 | if (I_PARMRK(tty)) { |
1082 | put_tty_queue('\377', tty); | |
1083 | put_tty_queue('\0', tty); | |
1084 | put_tty_queue(c, tty); | |
1085 | } else if (I_INPCK(tty)) | |
1086 | put_tty_queue('\0', tty); | |
1087 | else | |
1088 | put_tty_queue(c, tty); | |
1089 | wake_up_interruptible(&tty->read_wait); | |
1090 | } | |
1091 | ||
1092 | /** | |
1093 | * n_tty_receive_char - perform processing | |
1094 | * @tty: terminal device | |
1095 | * @c: character | |
1096 | * | |
1097 | * Process an individual character of input received from the driver. | |
4edf1827 | 1098 | * This is serialized with respect to itself by the rules for the |
1da177e4 LT |
1099 | * driver above. |
1100 | */ | |
1101 | ||
1102 | static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) | |
1103 | { | |
1104 | unsigned long flags; | |
acc71bba | 1105 | int parmrk; |
1da177e4 LT |
1106 | |
1107 | if (tty->raw) { | |
1108 | put_tty_queue(c, tty); | |
1109 | return; | |
1110 | } | |
4edf1827 | 1111 | |
1da177e4 LT |
1112 | if (I_ISTRIP(tty)) |
1113 | c &= 0x7f; | |
1114 | if (I_IUCLC(tty) && L_IEXTEN(tty)) | |
300a6204 | 1115 | c = tolower(c); |
1da177e4 | 1116 | |
26df6d13 | 1117 | if (L_EXTPROC(tty)) { |
1118 | put_tty_queue(c, tty); | |
1119 | return; | |
1120 | } | |
1121 | ||
54d2a37e | 1122 | if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && |
a88a69c9 JP |
1123 | I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) && |
1124 | c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) { | |
54d2a37e | 1125 | start_tty(tty); |
a88a69c9 JP |
1126 | process_echoes(tty); |
1127 | } | |
54d2a37e | 1128 | |
1da177e4 LT |
1129 | if (tty->closing) { |
1130 | if (I_IXON(tty)) { | |
a88a69c9 | 1131 | if (c == START_CHAR(tty)) { |
1da177e4 | 1132 | start_tty(tty); |
a88a69c9 | 1133 | process_echoes(tty); |
300a6204 | 1134 | } else if (c == STOP_CHAR(tty)) |
1da177e4 LT |
1135 | stop_tty(tty); |
1136 | } | |
1137 | return; | |
1138 | } | |
1139 | ||
1140 | /* | |
1141 | * If the previous character was LNEXT, or we know that this | |
1142 | * character is not one of the characters that we'll have to | |
1143 | * handle specially, do shortcut processing to speed things | |
1144 | * up. | |
1145 | */ | |
1146 | if (!test_bit(c, tty->process_char_map) || tty->lnext) { | |
1da177e4 | 1147 | tty->lnext = 0; |
acc71bba JP |
1148 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; |
1149 | if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) { | |
1150 | /* beep if no space */ | |
7e94b1d9 JP |
1151 | if (L_ECHO(tty)) |
1152 | process_output('\a', tty); | |
acc71bba JP |
1153 | return; |
1154 | } | |
1155 | if (L_ECHO(tty)) { | |
1156 | finish_erasing(tty); | |
1da177e4 LT |
1157 | /* Record the column of first canon char. */ |
1158 | if (tty->canon_head == tty->read_head) | |
a88a69c9 | 1159 | echo_set_canon_col(tty); |
1da177e4 | 1160 | echo_char(c, tty); |
a88a69c9 | 1161 | process_echoes(tty); |
1da177e4 | 1162 | } |
acc71bba | 1163 | if (parmrk) |
1da177e4 LT |
1164 | put_tty_queue(c, tty); |
1165 | put_tty_queue(c, tty); | |
1166 | return; | |
1167 | } | |
4edf1827 | 1168 | |
1da177e4 LT |
1169 | if (I_IXON(tty)) { |
1170 | if (c == START_CHAR(tty)) { | |
1171 | start_tty(tty); | |
a88a69c9 | 1172 | process_echoes(tty); |
1da177e4 LT |
1173 | return; |
1174 | } | |
1175 | if (c == STOP_CHAR(tty)) { | |
1176 | stop_tty(tty); | |
1177 | return; | |
1178 | } | |
1179 | } | |
575537b3 | 1180 | |
1da177e4 LT |
1181 | if (L_ISIG(tty)) { |
1182 | int signal; | |
1183 | signal = SIGINT; | |
1184 | if (c == INTR_CHAR(tty)) | |
1185 | goto send_signal; | |
1186 | signal = SIGQUIT; | |
1187 | if (c == QUIT_CHAR(tty)) | |
1188 | goto send_signal; | |
1189 | signal = SIGTSTP; | |
1190 | if (c == SUSP_CHAR(tty)) { | |
1191 | send_signal: | |
ec5b1157 | 1192 | /* |
ec5b1157 JP |
1193 | * Note that we do not use isig() here because we want |
1194 | * the order to be: | |
1195 | * 1) flush, 2) echo, 3) signal | |
1196 | */ | |
1197 | if (!L_NOFLSH(tty)) { | |
1198 | n_tty_flush_buffer(tty); | |
f34d7a5b | 1199 | tty_driver_flush_buffer(tty); |
ec5b1157 | 1200 | } |
a88a69c9 JP |
1201 | if (I_IXON(tty)) |
1202 | start_tty(tty); | |
1203 | if (L_ECHO(tty)) { | |
ec5b1157 | 1204 | echo_char(c, tty); |
a88a69c9 JP |
1205 | process_echoes(tty); |
1206 | } | |
ec5b1157 JP |
1207 | if (tty->pgrp) |
1208 | kill_pgrp(tty->pgrp, signal, 1); | |
1da177e4 LT |
1209 | return; |
1210 | } | |
1211 | } | |
575537b3 JP |
1212 | |
1213 | if (c == '\r') { | |
1214 | if (I_IGNCR(tty)) | |
1215 | return; | |
1216 | if (I_ICRNL(tty)) | |
1217 | c = '\n'; | |
1218 | } else if (c == '\n' && I_INLCR(tty)) | |
1219 | c = '\r'; | |
1220 | ||
1da177e4 LT |
1221 | if (tty->icanon) { |
1222 | if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || | |
1223 | (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { | |
1224 | eraser(c, tty); | |
a88a69c9 | 1225 | process_echoes(tty); |
1da177e4 LT |
1226 | return; |
1227 | } | |
1228 | if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { | |
1229 | tty->lnext = 1; | |
1230 | if (L_ECHO(tty)) { | |
1231 | finish_erasing(tty); | |
1232 | if (L_ECHOCTL(tty)) { | |
a88a69c9 JP |
1233 | echo_char_raw('^', tty); |
1234 | echo_char_raw('\b', tty); | |
1235 | process_echoes(tty); | |
1da177e4 LT |
1236 | } |
1237 | } | |
1238 | return; | |
1239 | } | |
1240 | if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && | |
1241 | L_IEXTEN(tty)) { | |
1242 | unsigned long tail = tty->canon_head; | |
1243 | ||
1244 | finish_erasing(tty); | |
1245 | echo_char(c, tty); | |
a88a69c9 | 1246 | echo_char_raw('\n', tty); |
1da177e4 LT |
1247 | while (tail != tty->read_head) { |
1248 | echo_char(tty->read_buf[tail], tty); | |
1249 | tail = (tail+1) & (N_TTY_BUF_SIZE-1); | |
1250 | } | |
a88a69c9 | 1251 | process_echoes(tty); |
1da177e4 LT |
1252 | return; |
1253 | } | |
1254 | if (c == '\n') { | |
acc71bba | 1255 | if (tty->read_cnt >= N_TTY_BUF_SIZE) { |
7e94b1d9 JP |
1256 | if (L_ECHO(tty)) |
1257 | process_output('\a', tty); | |
acc71bba JP |
1258 | return; |
1259 | } | |
1260 | if (L_ECHO(tty) || L_ECHONL(tty)) { | |
a88a69c9 JP |
1261 | echo_char_raw('\n', tty); |
1262 | process_echoes(tty); | |
1da177e4 LT |
1263 | } |
1264 | goto handle_newline; | |
1265 | } | |
1266 | if (c == EOF_CHAR(tty)) { | |
acc71bba JP |
1267 | if (tty->read_cnt >= N_TTY_BUF_SIZE) |
1268 | return; | |
4edf1827 AC |
1269 | if (tty->canon_head != tty->read_head) |
1270 | set_bit(TTY_PUSH, &tty->flags); | |
1da177e4 LT |
1271 | c = __DISABLED_CHAR; |
1272 | goto handle_newline; | |
1273 | } | |
1274 | if ((c == EOL_CHAR(tty)) || | |
1275 | (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) { | |
acc71bba JP |
1276 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) |
1277 | ? 1 : 0; | |
1278 | if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) { | |
7e94b1d9 JP |
1279 | if (L_ECHO(tty)) |
1280 | process_output('\a', tty); | |
acc71bba JP |
1281 | return; |
1282 | } | |
1da177e4 LT |
1283 | /* |
1284 | * XXX are EOL_CHAR and EOL2_CHAR echoed?!? | |
1285 | */ | |
1286 | if (L_ECHO(tty)) { | |
1da177e4 LT |
1287 | /* Record the column of first canon char. */ |
1288 | if (tty->canon_head == tty->read_head) | |
a88a69c9 | 1289 | echo_set_canon_col(tty); |
1da177e4 | 1290 | echo_char(c, tty); |
a88a69c9 | 1291 | process_echoes(tty); |
1da177e4 LT |
1292 | } |
1293 | /* | |
1294 | * XXX does PARMRK doubling happen for | |
1295 | * EOL_CHAR and EOL2_CHAR? | |
1296 | */ | |
acc71bba | 1297 | if (parmrk) |
1da177e4 LT |
1298 | put_tty_queue(c, tty); |
1299 | ||
4edf1827 | 1300 | handle_newline: |
1da177e4 LT |
1301 | spin_lock_irqsave(&tty->read_lock, flags); |
1302 | set_bit(tty->read_head, tty->read_flags); | |
1303 | put_tty_queue_nolock(c, tty); | |
1304 | tty->canon_head = tty->read_head; | |
1305 | tty->canon_data++; | |
1306 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
1307 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); | |
1308 | if (waitqueue_active(&tty->read_wait)) | |
1309 | wake_up_interruptible(&tty->read_wait); | |
1310 | return; | |
1311 | } | |
1312 | } | |
4edf1827 | 1313 | |
acc71bba JP |
1314 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; |
1315 | if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) { | |
1316 | /* beep if no space */ | |
7e94b1d9 JP |
1317 | if (L_ECHO(tty)) |
1318 | process_output('\a', tty); | |
acc71bba JP |
1319 | return; |
1320 | } | |
1321 | if (L_ECHO(tty)) { | |
1322 | finish_erasing(tty); | |
1da177e4 | 1323 | if (c == '\n') |
a88a69c9 | 1324 | echo_char_raw('\n', tty); |
1da177e4 LT |
1325 | else { |
1326 | /* Record the column of first canon char. */ | |
1327 | if (tty->canon_head == tty->read_head) | |
a88a69c9 | 1328 | echo_set_canon_col(tty); |
1da177e4 LT |
1329 | echo_char(c, tty); |
1330 | } | |
a88a69c9 | 1331 | process_echoes(tty); |
1da177e4 LT |
1332 | } |
1333 | ||
acc71bba | 1334 | if (parmrk) |
1da177e4 LT |
1335 | put_tty_queue(c, tty); |
1336 | ||
1337 | put_tty_queue(c, tty); | |
4edf1827 | 1338 | } |
1da177e4 | 1339 | |
1da177e4 LT |
1340 | |
1341 | /** | |
1342 | * n_tty_write_wakeup - asynchronous I/O notifier | |
1343 | * @tty: tty device | |
1344 | * | |
1345 | * Required for the ptys, serial driver etc. since processes | |
1346 | * that attach themselves to the master and rely on ASYNC | |
1347 | * IO must be woken up | |
1348 | */ | |
1349 | ||
1350 | static void n_tty_write_wakeup(struct tty_struct *tty) | |
1351 | { | |
ff8cb0fd | 1352 | if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) |
1da177e4 | 1353 | kill_fasync(&tty->fasync, SIGIO, POLL_OUT); |
1da177e4 LT |
1354 | } |
1355 | ||
1356 | /** | |
1357 | * n_tty_receive_buf - data receive | |
1358 | * @tty: terminal device | |
1359 | * @cp: buffer | |
1360 | * @fp: flag buffer | |
1361 | * @count: characters | |
1362 | * | |
1363 | * Called by the terminal driver when a block of characters has | |
1364 | * been received. This function must be called from soft contexts | |
1365 | * not from interrupt context. The driver is responsible for making | |
1366 | * calls one at a time and in order (or using flush_to_ldisc) | |
1367 | */ | |
4edf1827 | 1368 | |
55db4c64 LT |
1369 | static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, |
1370 | char *fp, int count) | |
1da177e4 LT |
1371 | { |
1372 | const unsigned char *p; | |
1373 | char *f, flags = TTY_NORMAL; | |
1374 | int i; | |
1375 | char buf[64]; | |
1376 | unsigned long cpuflags; | |
1377 | ||
1378 | if (!tty->read_buf) | |
55db4c64 | 1379 | return; |
1da177e4 LT |
1380 | |
1381 | if (tty->real_raw) { | |
1382 | spin_lock_irqsave(&tty->read_lock, cpuflags); | |
1383 | i = min(N_TTY_BUF_SIZE - tty->read_cnt, | |
1384 | N_TTY_BUF_SIZE - tty->read_head); | |
1385 | i = min(count, i); | |
1386 | memcpy(tty->read_buf + tty->read_head, cp, i); | |
1387 | tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); | |
1388 | tty->read_cnt += i; | |
1389 | cp += i; | |
1390 | count -= i; | |
1391 | ||
1392 | i = min(N_TTY_BUF_SIZE - tty->read_cnt, | |
1393 | N_TTY_BUF_SIZE - tty->read_head); | |
1394 | i = min(count, i); | |
1395 | memcpy(tty->read_buf + tty->read_head, cp, i); | |
1396 | tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); | |
1397 | tty->read_cnt += i; | |
1398 | spin_unlock_irqrestore(&tty->read_lock, cpuflags); | |
1399 | } else { | |
4edf1827 | 1400 | for (i = count, p = cp, f = fp; i; i--, p++) { |
1da177e4 LT |
1401 | if (f) |
1402 | flags = *f++; | |
1403 | switch (flags) { | |
1404 | case TTY_NORMAL: | |
1405 | n_tty_receive_char(tty, *p); | |
1406 | break; | |
1407 | case TTY_BREAK: | |
1408 | n_tty_receive_break(tty); | |
1409 | break; | |
1410 | case TTY_PARITY: | |
1411 | case TTY_FRAME: | |
1412 | n_tty_receive_parity_error(tty, *p); | |
1413 | break; | |
1414 | case TTY_OVERRUN: | |
1415 | n_tty_receive_overrun(tty); | |
1416 | break; | |
1417 | default: | |
4edf1827 | 1418 | printk(KERN_ERR "%s: unknown flag %d\n", |
1da177e4 LT |
1419 | tty_name(tty, buf), flags); |
1420 | break; | |
1421 | } | |
1422 | } | |
f34d7a5b AC |
1423 | if (tty->ops->flush_chars) |
1424 | tty->ops->flush_chars(tty); | |
1da177e4 LT |
1425 | } |
1426 | ||
55db4c64 LT |
1427 | n_tty_set_room(tty); |
1428 | ||
26df6d13 | 1429 | if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) || |
1430 | L_EXTPROC(tty)) { | |
1da177e4 LT |
1431 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); |
1432 | if (waitqueue_active(&tty->read_wait)) | |
1433 | wake_up_interruptible(&tty->read_wait); | |
1434 | } | |
1435 | ||
1436 | /* | |
1437 | * Check the remaining room for the input canonicalization | |
1438 | * mode. We don't want to throttle the driver if we're in | |
1439 | * canonical mode and don't have a newline yet! | |
1440 | */ | |
55db4c64 | 1441 | if (tty->receive_room < TTY_THRESHOLD_THROTTLE) |
39c2e60f | 1442 | tty_throttle(tty); |
0a44ab41 AC |
1443 | |
1444 | /* FIXME: there is a tiny race here if the receive room check runs | |
1445 | before the other work executes and empties the buffer (upping | |
1446 | the receiving room and unthrottling. We then throttle and get | |
1447 | stuck. This has been observed and traced down by Vincent Pillet/ | |
1448 | We need to address this when we sort out out the rx path locking */ | |
1da177e4 LT |
1449 | } |
1450 | ||
1451 | int is_ignored(int sig) | |
1452 | { | |
1453 | return (sigismember(¤t->blocked, sig) || | |
4edf1827 | 1454 | current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); |
1da177e4 LT |
1455 | } |
1456 | ||
1457 | /** | |
1458 | * n_tty_set_termios - termios data changed | |
1459 | * @tty: terminal | |
1460 | * @old: previous data | |
1461 | * | |
1462 | * Called by the tty layer when the user changes termios flags so | |
1463 | * that the line discipline can plan ahead. This function cannot sleep | |
4edf1827 | 1464 | * and is protected from re-entry by the tty layer. The user is |
1da177e4 LT |
1465 | * guaranteed that this function will not be re-entered or in progress |
1466 | * when the ldisc is closed. | |
17b82060 AC |
1467 | * |
1468 | * Locking: Caller holds tty->termios_mutex | |
1da177e4 | 1469 | */ |
4edf1827 AC |
1470 | |
1471 | static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) | |
1da177e4 | 1472 | { |
47afa7a5 AC |
1473 | int canon_change = 1; |
1474 | BUG_ON(!tty); | |
1475 | ||
1476 | if (old) | |
adc8d746 | 1477 | canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON; |
47afa7a5 AC |
1478 | if (canon_change) { |
1479 | memset(&tty->read_flags, 0, sizeof tty->read_flags); | |
1480 | tty->canon_head = tty->read_tail; | |
1481 | tty->canon_data = 0; | |
1482 | tty->erasing = 0; | |
1483 | } | |
1484 | ||
1485 | if (canon_change && !L_ICANON(tty) && tty->read_cnt) | |
1486 | wake_up_interruptible(&tty->read_wait); | |
4edf1827 | 1487 | |
1da177e4 LT |
1488 | tty->icanon = (L_ICANON(tty) != 0); |
1489 | if (test_bit(TTY_HW_COOK_IN, &tty->flags)) { | |
1490 | tty->raw = 1; | |
1491 | tty->real_raw = 1; | |
55db4c64 | 1492 | n_tty_set_room(tty); |
1da177e4 LT |
1493 | return; |
1494 | } | |
1495 | if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) || | |
1496 | I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) || | |
1497 | I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) || | |
1498 | I_PARMRK(tty)) { | |
1499 | memset(tty->process_char_map, 0, 256/8); | |
1500 | ||
1501 | if (I_IGNCR(tty) || I_ICRNL(tty)) | |
1502 | set_bit('\r', tty->process_char_map); | |
1503 | if (I_INLCR(tty)) | |
1504 | set_bit('\n', tty->process_char_map); | |
1505 | ||
1506 | if (L_ICANON(tty)) { | |
1507 | set_bit(ERASE_CHAR(tty), tty->process_char_map); | |
1508 | set_bit(KILL_CHAR(tty), tty->process_char_map); | |
1509 | set_bit(EOF_CHAR(tty), tty->process_char_map); | |
1510 | set_bit('\n', tty->process_char_map); | |
1511 | set_bit(EOL_CHAR(tty), tty->process_char_map); | |
1512 | if (L_IEXTEN(tty)) { | |
1513 | set_bit(WERASE_CHAR(tty), | |
1514 | tty->process_char_map); | |
1515 | set_bit(LNEXT_CHAR(tty), | |
1516 | tty->process_char_map); | |
1517 | set_bit(EOL2_CHAR(tty), | |
1518 | tty->process_char_map); | |
1519 | if (L_ECHO(tty)) | |
1520 | set_bit(REPRINT_CHAR(tty), | |
1521 | tty->process_char_map); | |
1522 | } | |
1523 | } | |
1524 | if (I_IXON(tty)) { | |
1525 | set_bit(START_CHAR(tty), tty->process_char_map); | |
1526 | set_bit(STOP_CHAR(tty), tty->process_char_map); | |
1527 | } | |
1528 | if (L_ISIG(tty)) { | |
1529 | set_bit(INTR_CHAR(tty), tty->process_char_map); | |
1530 | set_bit(QUIT_CHAR(tty), tty->process_char_map); | |
1531 | set_bit(SUSP_CHAR(tty), tty->process_char_map); | |
1532 | } | |
1533 | clear_bit(__DISABLED_CHAR, tty->process_char_map); | |
1534 | tty->raw = 0; | |
1535 | tty->real_raw = 0; | |
1536 | } else { | |
1537 | tty->raw = 1; | |
1538 | if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) && | |
1539 | (I_IGNPAR(tty) || !I_INPCK(tty)) && | |
1540 | (tty->driver->flags & TTY_DRIVER_REAL_RAW)) | |
1541 | tty->real_raw = 1; | |
1542 | else | |
1543 | tty->real_raw = 0; | |
1544 | } | |
55db4c64 | 1545 | n_tty_set_room(tty); |
f34d7a5b AC |
1546 | /* The termios change make the tty ready for I/O */ |
1547 | wake_up_interruptible(&tty->write_wait); | |
1548 | wake_up_interruptible(&tty->read_wait); | |
1da177e4 LT |
1549 | } |
1550 | ||
1551 | /** | |
1552 | * n_tty_close - close the ldisc for this tty | |
1553 | * @tty: device | |
1554 | * | |
4edf1827 AC |
1555 | * Called from the terminal layer when this line discipline is |
1556 | * being shut down, either because of a close or becsuse of a | |
1da177e4 LT |
1557 | * discipline change. The function will not be called while other |
1558 | * ldisc methods are in progress. | |
1559 | */ | |
4edf1827 | 1560 | |
1da177e4 LT |
1561 | static void n_tty_close(struct tty_struct *tty) |
1562 | { | |
1563 | n_tty_flush_buffer(tty); | |
1564 | if (tty->read_buf) { | |
0b4068a1 | 1565 | kfree(tty->read_buf); |
1da177e4 LT |
1566 | tty->read_buf = NULL; |
1567 | } | |
a88a69c9 | 1568 | if (tty->echo_buf) { |
0b4068a1 | 1569 | kfree(tty->echo_buf); |
a88a69c9 JP |
1570 | tty->echo_buf = NULL; |
1571 | } | |
1da177e4 LT |
1572 | } |
1573 | ||
1574 | /** | |
1575 | * n_tty_open - open an ldisc | |
1576 | * @tty: terminal to open | |
1577 | * | |
4edf1827 | 1578 | * Called when this line discipline is being attached to the |
1da177e4 LT |
1579 | * terminal device. Can sleep. Called serialized so that no |
1580 | * other events will occur in parallel. No further open will occur | |
1581 | * until a close. | |
1582 | */ | |
1583 | ||
1584 | static int n_tty_open(struct tty_struct *tty) | |
1585 | { | |
1586 | if (!tty) | |
1587 | return -EINVAL; | |
1588 | ||
a88a69c9 | 1589 | /* These are ugly. Currently a malloc failure here can panic */ |
1da177e4 | 1590 | if (!tty->read_buf) { |
0b4068a1 | 1591 | tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
1da177e4 LT |
1592 | if (!tty->read_buf) |
1593 | return -ENOMEM; | |
1594 | } | |
a88a69c9 | 1595 | if (!tty->echo_buf) { |
0b4068a1 AC |
1596 | tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
1597 | ||
a88a69c9 JP |
1598 | if (!tty->echo_buf) |
1599 | return -ENOMEM; | |
1600 | } | |
1da177e4 | 1601 | reset_buffer_flags(tty); |
7b292b4b | 1602 | tty_unthrottle(tty); |
1da177e4 LT |
1603 | tty->column = 0; |
1604 | n_tty_set_termios(tty, NULL); | |
1605 | tty->minimum_to_wake = 1; | |
1606 | tty->closing = 0; | |
1607 | return 0; | |
1608 | } | |
1609 | ||
1610 | static inline int input_available_p(struct tty_struct *tty, int amt) | |
1611 | { | |
e043e42b | 1612 | tty_flush_to_ldisc(tty); |
26df6d13 | 1613 | if (tty->icanon && !L_EXTPROC(tty)) { |
1da177e4 LT |
1614 | if (tty->canon_data) |
1615 | return 1; | |
1616 | } else if (tty->read_cnt >= (amt ? amt : 1)) | |
1617 | return 1; | |
1618 | ||
1619 | return 0; | |
1620 | } | |
1621 | ||
1622 | /** | |
bbd20759 | 1623 | * copy_from_read_buf - copy read data directly |
1da177e4 LT |
1624 | * @tty: terminal device |
1625 | * @b: user data | |
1626 | * @nr: size of data | |
1627 | * | |
11a96d18 | 1628 | * Helper function to speed up n_tty_read. It is only called when |
1da177e4 LT |
1629 | * ICANON is off; it copies characters straight from the tty queue to |
1630 | * user space directly. It can be profitably called twice; once to | |
1631 | * drain the space from the tail pointer to the (physical) end of the | |
1632 | * buffer, and once to drain the space from the (physical) beginning of | |
1633 | * the buffer to head pointer. | |
1634 | * | |
817d6d3b | 1635 | * Called under the tty->atomic_read_lock sem |
1da177e4 LT |
1636 | * |
1637 | */ | |
4edf1827 | 1638 | |
33f0f88f | 1639 | static int copy_from_read_buf(struct tty_struct *tty, |
1da177e4 LT |
1640 | unsigned char __user **b, |
1641 | size_t *nr) | |
1642 | ||
1643 | { | |
1644 | int retval; | |
1645 | size_t n; | |
1646 | unsigned long flags; | |
3fa10cc8 | 1647 | bool is_eof; |
1da177e4 LT |
1648 | |
1649 | retval = 0; | |
1650 | spin_lock_irqsave(&tty->read_lock, flags); | |
1651 | n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail); | |
1652 | n = min(*nr, n); | |
1653 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
1654 | if (n) { | |
1da177e4 LT |
1655 | retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n); |
1656 | n -= retval; | |
3fa10cc8 JS |
1657 | is_eof = n == 1 && |
1658 | tty->read_buf[tty->read_tail] == EOF_CHAR(tty); | |
522ed776 | 1659 | tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n); |
1da177e4 LT |
1660 | spin_lock_irqsave(&tty->read_lock, flags); |
1661 | tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1); | |
1662 | tty->read_cnt -= n; | |
26df6d13 | 1663 | /* Turn single EOF into zero-length read */ |
3fa10cc8 JS |
1664 | if (L_EXTPROC(tty) && tty->icanon && is_eof && !tty->read_cnt) |
1665 | n = 0; | |
1da177e4 LT |
1666 | spin_unlock_irqrestore(&tty->read_lock, flags); |
1667 | *b += n; | |
1668 | *nr -= n; | |
1669 | } | |
1670 | return retval; | |
1671 | } | |
1672 | ||
cc4191dc | 1673 | extern ssize_t redirected_tty_write(struct file *, const char __user *, |
4edf1827 | 1674 | size_t, loff_t *); |
1da177e4 LT |
1675 | |
1676 | /** | |
1677 | * job_control - check job control | |
1678 | * @tty: tty | |
1679 | * @file: file handle | |
1680 | * | |
1681 | * Perform job control management checks on this file/tty descriptor | |
4edf1827 | 1682 | * and if appropriate send any needed signals and return a negative |
1da177e4 | 1683 | * error code if action should be taken. |
04f378b1 AC |
1684 | * |
1685 | * FIXME: | |
1686 | * Locking: None - redirected write test is safe, testing | |
1687 | * current->signal should possibly lock current->sighand | |
1688 | * pgrp locking ? | |
1da177e4 | 1689 | */ |
4edf1827 | 1690 | |
1da177e4 LT |
1691 | static int job_control(struct tty_struct *tty, struct file *file) |
1692 | { | |
1693 | /* Job control check -- must be done at start and after | |
1694 | every sleep (POSIX.1 7.1.1.4). */ | |
1695 | /* NOTE: not yet done after every sleep pending a thorough | |
1696 | check of the logic of this change. -- jlc */ | |
1697 | /* don't stop on /dev/console */ | |
1698 | if (file->f_op->write != redirected_tty_write && | |
1699 | current->signal->tty == tty) { | |
ab521dc0 | 1700 | if (!tty->pgrp) |
11a96d18 | 1701 | printk(KERN_ERR "n_tty_read: no tty->pgrp!\n"); |
ab521dc0 | 1702 | else if (task_pgrp(current) != tty->pgrp) { |
1da177e4 | 1703 | if (is_ignored(SIGTTIN) || |
3e7cd6c4 | 1704 | is_current_pgrp_orphaned()) |
1da177e4 | 1705 | return -EIO; |
ab521dc0 | 1706 | kill_pgrp(task_pgrp(current), SIGTTIN, 1); |
040b6362 | 1707 | set_thread_flag(TIF_SIGPENDING); |
1da177e4 LT |
1708 | return -ERESTARTSYS; |
1709 | } | |
1710 | } | |
1711 | return 0; | |
1712 | } | |
4edf1827 | 1713 | |
1da177e4 LT |
1714 | |
1715 | /** | |
11a96d18 | 1716 | * n_tty_read - read function for tty |
1da177e4 LT |
1717 | * @tty: tty device |
1718 | * @file: file object | |
1719 | * @buf: userspace buffer pointer | |
1720 | * @nr: size of I/O | |
1721 | * | |
1722 | * Perform reads for the line discipline. We are guaranteed that the | |
1723 | * line discipline will not be closed under us but we may get multiple | |
1724 | * parallel readers and must handle this ourselves. We may also get | |
1725 | * a hangup. Always called in user context, may sleep. | |
1726 | * | |
1727 | * This code must be sure never to sleep through a hangup. | |
1728 | */ | |
4edf1827 | 1729 | |
11a96d18 | 1730 | static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, |
1da177e4 LT |
1731 | unsigned char __user *buf, size_t nr) |
1732 | { | |
1733 | unsigned char __user *b = buf; | |
1734 | DECLARE_WAITQUEUE(wait, current); | |
1735 | int c; | |
1736 | int minimum, time; | |
1737 | ssize_t retval = 0; | |
1738 | ssize_t size; | |
1739 | long timeout; | |
1740 | unsigned long flags; | |
04f378b1 | 1741 | int packet; |
1da177e4 LT |
1742 | |
1743 | do_it_again: | |
1744 | ||
e9490e93 SK |
1745 | if (WARN_ON(!tty->read_buf)) |
1746 | return -EAGAIN; | |
1da177e4 LT |
1747 | |
1748 | c = job_control(tty, file); | |
4edf1827 | 1749 | if (c < 0) |
1da177e4 | 1750 | return c; |
4edf1827 | 1751 | |
1da177e4 LT |
1752 | minimum = time = 0; |
1753 | timeout = MAX_SCHEDULE_TIMEOUT; | |
1754 | if (!tty->icanon) { | |
1755 | time = (HZ / 10) * TIME_CHAR(tty); | |
1756 | minimum = MIN_CHAR(tty); | |
1757 | if (minimum) { | |
1758 | if (time) | |
1759 | tty->minimum_to_wake = 1; | |
1760 | else if (!waitqueue_active(&tty->read_wait) || | |
1761 | (tty->minimum_to_wake > minimum)) | |
1762 | tty->minimum_to_wake = minimum; | |
1763 | } else { | |
1764 | timeout = 0; | |
1765 | if (time) { | |
1766 | timeout = time; | |
1767 | time = 0; | |
1768 | } | |
1769 | tty->minimum_to_wake = minimum = 1; | |
1770 | } | |
1771 | } | |
1772 | ||
1773 | /* | |
1774 | * Internal serialization of reads. | |
1775 | */ | |
1776 | if (file->f_flags & O_NONBLOCK) { | |
70522e12 | 1777 | if (!mutex_trylock(&tty->atomic_read_lock)) |
1da177e4 | 1778 | return -EAGAIN; |
4edf1827 | 1779 | } else { |
70522e12 | 1780 | if (mutex_lock_interruptible(&tty->atomic_read_lock)) |
1da177e4 LT |
1781 | return -ERESTARTSYS; |
1782 | } | |
04f378b1 | 1783 | packet = tty->packet; |
1da177e4 LT |
1784 | |
1785 | add_wait_queue(&tty->read_wait, &wait); | |
1da177e4 LT |
1786 | while (nr) { |
1787 | /* First test for status change. */ | |
04f378b1 | 1788 | if (packet && tty->link->ctrl_status) { |
1da177e4 LT |
1789 | unsigned char cs; |
1790 | if (b != buf) | |
1791 | break; | |
04f378b1 | 1792 | spin_lock_irqsave(&tty->link->ctrl_lock, flags); |
1da177e4 LT |
1793 | cs = tty->link->ctrl_status; |
1794 | tty->link->ctrl_status = 0; | |
04f378b1 | 1795 | spin_unlock_irqrestore(&tty->link->ctrl_lock, flags); |
522ed776 | 1796 | if (tty_put_user(tty, cs, b++)) { |
1da177e4 LT |
1797 | retval = -EFAULT; |
1798 | b--; | |
1799 | break; | |
1800 | } | |
1801 | nr--; | |
1802 | break; | |
1803 | } | |
1804 | /* This statement must be first before checking for input | |
1805 | so that any interrupt will set the state back to | |
1806 | TASK_RUNNING. */ | |
1807 | set_current_state(TASK_INTERRUPTIBLE); | |
4edf1827 | 1808 | |
1da177e4 LT |
1809 | if (((minimum - (b - buf)) < tty->minimum_to_wake) && |
1810 | ((minimum - (b - buf)) >= 1)) | |
1811 | tty->minimum_to_wake = (minimum - (b - buf)); | |
4edf1827 | 1812 | |
1da177e4 LT |
1813 | if (!input_available_p(tty, 0)) { |
1814 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { | |
1815 | retval = -EIO; | |
1816 | break; | |
1817 | } | |
1818 | if (tty_hung_up_p(file)) | |
1819 | break; | |
1820 | if (!timeout) | |
1821 | break; | |
1822 | if (file->f_flags & O_NONBLOCK) { | |
1823 | retval = -EAGAIN; | |
1824 | break; | |
1825 | } | |
1826 | if (signal_pending(current)) { | |
1827 | retval = -ERESTARTSYS; | |
1828 | break; | |
1829 | } | |
55db4c64 LT |
1830 | /* FIXME: does n_tty_set_room need locking ? */ |
1831 | n_tty_set_room(tty); | |
1da177e4 | 1832 | timeout = schedule_timeout(timeout); |
28726286 | 1833 | BUG_ON(!tty->read_buf); |
1da177e4 LT |
1834 | continue; |
1835 | } | |
1836 | __set_current_state(TASK_RUNNING); | |
1837 | ||
1838 | /* Deal with packet mode. */ | |
04f378b1 | 1839 | if (packet && b == buf) { |
522ed776 | 1840 | if (tty_put_user(tty, TIOCPKT_DATA, b++)) { |
1da177e4 LT |
1841 | retval = -EFAULT; |
1842 | b--; | |
1843 | break; | |
1844 | } | |
1845 | nr--; | |
1846 | } | |
1847 | ||
26df6d13 | 1848 | if (tty->icanon && !L_EXTPROC(tty)) { |
1da177e4 | 1849 | /* N.B. avoid overrun if nr == 0 */ |
00aaae03 | 1850 | spin_lock_irqsave(&tty->read_lock, flags); |
1da177e4 | 1851 | while (nr && tty->read_cnt) { |
4edf1827 | 1852 | int eol; |
1da177e4 LT |
1853 | |
1854 | eol = test_and_clear_bit(tty->read_tail, | |
1855 | tty->read_flags); | |
1856 | c = tty->read_buf[tty->read_tail]; | |
1da177e4 LT |
1857 | tty->read_tail = ((tty->read_tail+1) & |
1858 | (N_TTY_BUF_SIZE-1)); | |
1859 | tty->read_cnt--; | |
1860 | if (eol) { | |
1861 | /* this test should be redundant: | |
1862 | * we shouldn't be reading data if | |
1863 | * canon_data is 0 | |
1864 | */ | |
1865 | if (--tty->canon_data < 0) | |
1866 | tty->canon_data = 0; | |
1867 | } | |
1868 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
1869 | ||
1870 | if (!eol || (c != __DISABLED_CHAR)) { | |
522ed776 | 1871 | if (tty_put_user(tty, c, b++)) { |
1da177e4 LT |
1872 | retval = -EFAULT; |
1873 | b--; | |
00aaae03 | 1874 | spin_lock_irqsave(&tty->read_lock, flags); |
1da177e4 LT |
1875 | break; |
1876 | } | |
1877 | nr--; | |
1878 | } | |
522ed776 MT |
1879 | if (eol) { |
1880 | tty_audit_push(tty); | |
00aaae03 | 1881 | spin_lock_irqsave(&tty->read_lock, flags); |
1da177e4 | 1882 | break; |
522ed776 | 1883 | } |
00aaae03 | 1884 | spin_lock_irqsave(&tty->read_lock, flags); |
1da177e4 | 1885 | } |
00aaae03 | 1886 | spin_unlock_irqrestore(&tty->read_lock, flags); |
1da177e4 LT |
1887 | if (retval) |
1888 | break; | |
1889 | } else { | |
1890 | int uncopied; | |
04f378b1 AC |
1891 | /* The copy function takes the read lock and handles |
1892 | locking internally for this case */ | |
1da177e4 LT |
1893 | uncopied = copy_from_read_buf(tty, &b, &nr); |
1894 | uncopied += copy_from_read_buf(tty, &b, &nr); | |
1895 | if (uncopied) { | |
1896 | retval = -EFAULT; | |
1897 | break; | |
1898 | } | |
1899 | } | |
1900 | ||
1901 | /* If there is enough space in the read buffer now, let the | |
1902 | * low-level driver know. We use n_tty_chars_in_buffer() to | |
1903 | * check the buffer, as it now knows about canonical mode. | |
1904 | * Otherwise, if the driver is throttled and the line is | |
1905 | * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode, | |
1906 | * we won't get any more characters. | |
1907 | */ | |
55db4c64 LT |
1908 | if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) { |
1909 | n_tty_set_room(tty); | |
1da177e4 | 1910 | check_unthrottle(tty); |
55db4c64 | 1911 | } |
1da177e4 LT |
1912 | |
1913 | if (b - buf >= minimum) | |
1914 | break; | |
1915 | if (time) | |
1916 | timeout = time; | |
1917 | } | |
70522e12 | 1918 | mutex_unlock(&tty->atomic_read_lock); |
1da177e4 LT |
1919 | remove_wait_queue(&tty->read_wait, &wait); |
1920 | ||
1921 | if (!waitqueue_active(&tty->read_wait)) | |
1922 | tty->minimum_to_wake = minimum; | |
1923 | ||
1924 | __set_current_state(TASK_RUNNING); | |
1925 | size = b - buf; | |
1926 | if (size) { | |
1927 | retval = size; | |
1928 | if (nr) | |
4edf1827 | 1929 | clear_bit(TTY_PUSH, &tty->flags); |
1da177e4 | 1930 | } else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) |
bbd20759 | 1931 | goto do_it_again; |
1da177e4 | 1932 | |
55db4c64 | 1933 | n_tty_set_room(tty); |
1da177e4 LT |
1934 | return retval; |
1935 | } | |
1936 | ||
1937 | /** | |
11a96d18 | 1938 | * n_tty_write - write function for tty |
1da177e4 LT |
1939 | * @tty: tty device |
1940 | * @file: file object | |
1941 | * @buf: userspace buffer pointer | |
1942 | * @nr: size of I/O | |
1943 | * | |
a88a69c9 | 1944 | * Write function of the terminal device. This is serialized with |
1da177e4 | 1945 | * respect to other write callers but not to termios changes, reads |
a88a69c9 JP |
1946 | * and other such events. Since the receive code will echo characters, |
1947 | * thus calling driver write methods, the output_lock is used in | |
1948 | * the output processing functions called here as well as in the | |
1949 | * echo processing function to protect the column state and space | |
1950 | * left in the buffer. | |
1da177e4 LT |
1951 | * |
1952 | * This code must be sure never to sleep through a hangup. | |
a88a69c9 JP |
1953 | * |
1954 | * Locking: output_lock to protect column state and space left | |
1955 | * (note that the process_output*() functions take this | |
1956 | * lock themselves) | |
1da177e4 | 1957 | */ |
4edf1827 | 1958 | |
11a96d18 | 1959 | static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, |
a88a69c9 | 1960 | const unsigned char *buf, size_t nr) |
1da177e4 LT |
1961 | { |
1962 | const unsigned char *b = buf; | |
1963 | DECLARE_WAITQUEUE(wait, current); | |
1964 | int c; | |
1965 | ssize_t retval = 0; | |
1966 | ||
1967 | /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ | |
1968 | if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) { | |
1969 | retval = tty_check_change(tty); | |
1970 | if (retval) | |
1971 | return retval; | |
1972 | } | |
1973 | ||
a88a69c9 JP |
1974 | /* Write out any echoed characters that are still pending */ |
1975 | process_echoes(tty); | |
300a6204 | 1976 | |
1da177e4 LT |
1977 | add_wait_queue(&tty->write_wait, &wait); |
1978 | while (1) { | |
1979 | set_current_state(TASK_INTERRUPTIBLE); | |
1980 | if (signal_pending(current)) { | |
1981 | retval = -ERESTARTSYS; | |
1982 | break; | |
1983 | } | |
1984 | if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { | |
1985 | retval = -EIO; | |
1986 | break; | |
1987 | } | |
1988 | if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) { | |
1989 | while (nr > 0) { | |
a88a69c9 | 1990 | ssize_t num = process_output_block(tty, b, nr); |
1da177e4 LT |
1991 | if (num < 0) { |
1992 | if (num == -EAGAIN) | |
1993 | break; | |
1994 | retval = num; | |
1995 | goto break_out; | |
1996 | } | |
1997 | b += num; | |
1998 | nr -= num; | |
1999 | if (nr == 0) | |
2000 | break; | |
2001 | c = *b; | |
a88a69c9 | 2002 | if (process_output(c, tty) < 0) |
1da177e4 LT |
2003 | break; |
2004 | b++; nr--; | |
2005 | } | |
f34d7a5b AC |
2006 | if (tty->ops->flush_chars) |
2007 | tty->ops->flush_chars(tty); | |
1da177e4 | 2008 | } else { |
d6afe27b | 2009 | while (nr > 0) { |
f34d7a5b | 2010 | c = tty->ops->write(tty, b, nr); |
d6afe27b RZ |
2011 | if (c < 0) { |
2012 | retval = c; | |
2013 | goto break_out; | |
2014 | } | |
2015 | if (!c) | |
2016 | break; | |
2017 | b += c; | |
2018 | nr -= c; | |
1da177e4 | 2019 | } |
1da177e4 LT |
2020 | } |
2021 | if (!nr) | |
2022 | break; | |
2023 | if (file->f_flags & O_NONBLOCK) { | |
2024 | retval = -EAGAIN; | |
2025 | break; | |
2026 | } | |
2027 | schedule(); | |
2028 | } | |
2029 | break_out: | |
2030 | __set_current_state(TASK_RUNNING); | |
2031 | remove_wait_queue(&tty->write_wait, &wait); | |
ff8cb0fd TP |
2032 | if (b - buf != nr && tty->fasync) |
2033 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); | |
1da177e4 LT |
2034 | return (b - buf) ? b - buf : retval; |
2035 | } | |
2036 | ||
2037 | /** | |
11a96d18 | 2038 | * n_tty_poll - poll method for N_TTY |
1da177e4 LT |
2039 | * @tty: terminal device |
2040 | * @file: file accessing it | |
2041 | * @wait: poll table | |
2042 | * | |
2043 | * Called when the line discipline is asked to poll() for data or | |
2044 | * for special events. This code is not serialized with respect to | |
2045 | * other events save open/close. | |
2046 | * | |
2047 | * This code must be sure never to sleep through a hangup. | |
2048 | * Called without the kernel lock held - fine | |
1da177e4 | 2049 | */ |
4edf1827 | 2050 | |
11a96d18 | 2051 | static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file, |
4edf1827 | 2052 | poll_table *wait) |
1da177e4 LT |
2053 | { |
2054 | unsigned int mask = 0; | |
2055 | ||
2056 | poll_wait(file, &tty->read_wait, wait); | |
2057 | poll_wait(file, &tty->write_wait, wait); | |
2058 | if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty))) | |
2059 | mask |= POLLIN | POLLRDNORM; | |
2060 | if (tty->packet && tty->link->ctrl_status) | |
2061 | mask |= POLLPRI | POLLIN | POLLRDNORM; | |
2062 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
2063 | mask |= POLLHUP; | |
2064 | if (tty_hung_up_p(file)) | |
2065 | mask |= POLLHUP; | |
2066 | if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) { | |
2067 | if (MIN_CHAR(tty) && !TIME_CHAR(tty)) | |
2068 | tty->minimum_to_wake = MIN_CHAR(tty); | |
2069 | else | |
2070 | tty->minimum_to_wake = 1; | |
2071 | } | |
f34d7a5b AC |
2072 | if (tty->ops->write && !tty_is_writelocked(tty) && |
2073 | tty_chars_in_buffer(tty) < WAKEUP_CHARS && | |
2074 | tty_write_room(tty) > 0) | |
1da177e4 LT |
2075 | mask |= POLLOUT | POLLWRNORM; |
2076 | return mask; | |
2077 | } | |
2078 | ||
47afa7a5 AC |
2079 | static unsigned long inq_canon(struct tty_struct *tty) |
2080 | { | |
2081 | int nr, head, tail; | |
2082 | ||
17b82060 | 2083 | if (!tty->canon_data) |
47afa7a5 AC |
2084 | return 0; |
2085 | head = tty->canon_head; | |
2086 | tail = tty->read_tail; | |
2087 | nr = (head - tail) & (N_TTY_BUF_SIZE-1); | |
2088 | /* Skip EOF-chars.. */ | |
2089 | while (head != tail) { | |
2090 | if (test_bit(tail, tty->read_flags) && | |
2091 | tty->read_buf[tail] == __DISABLED_CHAR) | |
2092 | nr--; | |
2093 | tail = (tail+1) & (N_TTY_BUF_SIZE-1); | |
2094 | } | |
2095 | return nr; | |
2096 | } | |
2097 | ||
2098 | static int n_tty_ioctl(struct tty_struct *tty, struct file *file, | |
2099 | unsigned int cmd, unsigned long arg) | |
2100 | { | |
2101 | int retval; | |
2102 | ||
2103 | switch (cmd) { | |
2104 | case TIOCOUTQ: | |
2105 | return put_user(tty_chars_in_buffer(tty), (int __user *) arg); | |
2106 | case TIOCINQ: | |
17b82060 | 2107 | /* FIXME: Locking */ |
47afa7a5 AC |
2108 | retval = tty->read_cnt; |
2109 | if (L_ICANON(tty)) | |
2110 | retval = inq_canon(tty); | |
2111 | return put_user(retval, (unsigned int __user *) arg); | |
2112 | default: | |
2113 | return n_tty_ioctl_helper(tty, file, cmd, arg); | |
2114 | } | |
2115 | } | |
2116 | ||
a352def2 | 2117 | struct tty_ldisc_ops tty_ldisc_N_TTY = { |
e10cc1df PF |
2118 | .magic = TTY_LDISC_MAGIC, |
2119 | .name = "n_tty", | |
2120 | .open = n_tty_open, | |
2121 | .close = n_tty_close, | |
2122 | .flush_buffer = n_tty_flush_buffer, | |
2123 | .chars_in_buffer = n_tty_chars_in_buffer, | |
11a96d18 AC |
2124 | .read = n_tty_read, |
2125 | .write = n_tty_write, | |
e10cc1df PF |
2126 | .ioctl = n_tty_ioctl, |
2127 | .set_termios = n_tty_set_termios, | |
11a96d18 | 2128 | .poll = n_tty_poll, |
e10cc1df PF |
2129 | .receive_buf = n_tty_receive_buf, |
2130 | .write_wakeup = n_tty_write_wakeup | |
1da177e4 | 2131 | }; |
572b9adb RG |
2132 | |
2133 | /** | |
2134 | * n_tty_inherit_ops - inherit N_TTY methods | |
2135 | * @ops: struct tty_ldisc_ops where to save N_TTY methods | |
2136 | * | |
2137 | * Used by a generic struct tty_ldisc_ops to easily inherit N_TTY | |
2138 | * methods. | |
2139 | */ | |
2140 | ||
2141 | void n_tty_inherit_ops(struct tty_ldisc_ops *ops) | |
2142 | { | |
2143 | *ops = tty_ldisc_N_TTY; | |
2144 | ops->owner = NULL; | |
2145 | ops->refcount = ops->flags = 0; | |
2146 | } | |
2147 | EXPORT_SYMBOL_GPL(n_tty_inherit_ops); |