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Commit | Line | Data |
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1 | /* | |
2 | * n_tty.c --- implements the N_TTY line discipline. | |
3 | * | |
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 | |
11 | * to N_TTY if it can not switch to any other line discipline. | |
12 | * | |
13 | * Written by Theodore Ts'o, Copyright 1994. | |
14 | * | |
15 | * This file also contains code originally written by Linus Torvalds, | |
16 | * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994. | |
17 | * | |
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 | * | |
23 | * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of | |
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>. | |
29 | * Also fixed a bug in BLOCKING mode where n_tty_write returns | |
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> | |
48 | #include <linux/audit.h> | |
49 | #include <linux/file.h> | |
50 | #include <linux/uaccess.h> | |
51 | #include <linux/module.h> | |
52 | #include <linux/ratelimit.h> | |
53 | ||
54 | ||
55 | /* number of characters left in xmit buffer before select has we have room */ | |
56 | #define WAKEUP_CHARS 256 | |
57 | ||
58 | /* | |
59 | * This defines the low- and high-watermarks for throttling and | |
60 | * unthrottling the TTY driver. These watermarks are used for | |
61 | * controlling the space in the read buffer. | |
62 | */ | |
63 | #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */ | |
64 | #define TTY_THRESHOLD_UNTHROTTLE 128 | |
65 | ||
66 | /* | |
67 | * Special byte codes used in the echo buffer to represent operations | |
68 | * or special handling of characters. Bytes in the echo buffer that | |
69 | * are not part of such special blocks are treated as normal character | |
70 | * codes. | |
71 | */ | |
72 | #define ECHO_OP_START 0xff | |
73 | #define ECHO_OP_MOVE_BACK_COL 0x80 | |
74 | #define ECHO_OP_SET_CANON_COL 0x81 | |
75 | #define ECHO_OP_ERASE_TAB 0x82 | |
76 | ||
77 | #undef N_TTY_TRACE | |
78 | #ifdef N_TTY_TRACE | |
79 | # define n_tty_trace(f, args...) trace_printk(f, ##args) | |
80 | #else | |
81 | # define n_tty_trace(f, args...) | |
82 | #endif | |
83 | ||
84 | struct n_tty_data { | |
85 | /* producer-published */ | |
86 | size_t read_head; | |
87 | size_t canon_head; | |
88 | DECLARE_BITMAP(process_char_map, 256); | |
89 | ||
90 | /* private to n_tty_receive_overrun (single-threaded) */ | |
91 | unsigned long overrun_time; | |
92 | int num_overrun; | |
93 | ||
94 | /* non-atomic */ | |
95 | bool no_room; | |
96 | ||
97 | /* must hold exclusive termios_rwsem to reset these */ | |
98 | unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1; | |
99 | ||
100 | /* shared by producer and consumer */ | |
101 | char *read_buf; | |
102 | DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE); | |
103 | ||
104 | int minimum_to_wake; | |
105 | ||
106 | /* consumer-published */ | |
107 | size_t read_tail; | |
108 | ||
109 | unsigned char *echo_buf; | |
110 | size_t echo_head; | |
111 | size_t echo_tail; | |
112 | size_t echo_commit; | |
113 | ||
114 | /* protected by output lock */ | |
115 | unsigned int column; | |
116 | unsigned int canon_column; | |
117 | ||
118 | struct mutex atomic_read_lock; | |
119 | struct mutex output_lock; | |
120 | }; | |
121 | ||
122 | static inline size_t read_cnt(struct n_tty_data *ldata) | |
123 | { | |
124 | return ldata->read_head - ldata->read_tail; | |
125 | } | |
126 | ||
127 | static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i) | |
128 | { | |
129 | return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)]; | |
130 | } | |
131 | ||
132 | static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i) | |
133 | { | |
134 | return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)]; | |
135 | } | |
136 | ||
137 | static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i) | |
138 | { | |
139 | return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; | |
140 | } | |
141 | ||
142 | static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i) | |
143 | { | |
144 | return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; | |
145 | } | |
146 | ||
147 | static inline int tty_put_user(struct tty_struct *tty, unsigned char x, | |
148 | unsigned char __user *ptr) | |
149 | { | |
150 | struct n_tty_data *ldata = tty->disc_data; | |
151 | ||
152 | tty_audit_add_data(tty, &x, 1, ldata->icanon); | |
153 | return put_user(x, ptr); | |
154 | } | |
155 | ||
156 | static int receive_room(struct tty_struct *tty) | |
157 | { | |
158 | struct n_tty_data *ldata = tty->disc_data; | |
159 | int left; | |
160 | ||
161 | if (I_PARMRK(tty)) { | |
162 | /* Multiply read_cnt by 3, since each byte might take up to | |
163 | * three times as many spaces when PARMRK is set (depending on | |
164 | * its flags, e.g. parity error). */ | |
165 | left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1; | |
166 | } else | |
167 | left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1; | |
168 | ||
169 | /* | |
170 | * If we are doing input canonicalization, and there are no | |
171 | * pending newlines, let characters through without limit, so | |
172 | * that erase characters will be handled. Other excess | |
173 | * characters will be beeped. | |
174 | */ | |
175 | if (left <= 0) | |
176 | left = ldata->icanon && ldata->canon_head == ldata->read_tail; | |
177 | ||
178 | return left; | |
179 | } | |
180 | ||
181 | /** | |
182 | * n_tty_set_room - receive space | |
183 | * @tty: terminal | |
184 | * | |
185 | * Re-schedules the flip buffer work if space just became available. | |
186 | * | |
187 | * Caller holds exclusive termios_rwsem | |
188 | * or | |
189 | * n_tty_read()/consumer path: | |
190 | * holds non-exclusive termios_rwsem | |
191 | */ | |
192 | ||
193 | static void n_tty_set_room(struct tty_struct *tty) | |
194 | { | |
195 | struct n_tty_data *ldata = tty->disc_data; | |
196 | ||
197 | /* Did this open up the receive buffer? We may need to flip */ | |
198 | if (unlikely(ldata->no_room) && receive_room(tty)) { | |
199 | ldata->no_room = 0; | |
200 | ||
201 | WARN_RATELIMIT(tty->port->itty == NULL, | |
202 | "scheduling with invalid itty\n"); | |
203 | /* see if ldisc has been killed - if so, this means that | |
204 | * even though the ldisc has been halted and ->buf.work | |
205 | * cancelled, ->buf.work is about to be rescheduled | |
206 | */ | |
207 | WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags), | |
208 | "scheduling buffer work for halted ldisc\n"); | |
209 | queue_work(system_unbound_wq, &tty->port->buf.work); | |
210 | } | |
211 | } | |
212 | ||
213 | static ssize_t chars_in_buffer(struct tty_struct *tty) | |
214 | { | |
215 | struct n_tty_data *ldata = tty->disc_data; | |
216 | ssize_t n = 0; | |
217 | ||
218 | if (!ldata->icanon) | |
219 | n = read_cnt(ldata); | |
220 | else | |
221 | n = ldata->canon_head - ldata->read_tail; | |
222 | return n; | |
223 | } | |
224 | ||
225 | /** | |
226 | * n_tty_write_wakeup - asynchronous I/O notifier | |
227 | * @tty: tty device | |
228 | * | |
229 | * Required for the ptys, serial driver etc. since processes | |
230 | * that attach themselves to the master and rely on ASYNC | |
231 | * IO must be woken up | |
232 | */ | |
233 | ||
234 | static void n_tty_write_wakeup(struct tty_struct *tty) | |
235 | { | |
236 | if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) | |
237 | kill_fasync(&tty->fasync, SIGIO, POLL_OUT); | |
238 | } | |
239 | ||
240 | static inline void n_tty_check_throttle(struct tty_struct *tty) | |
241 | { | |
242 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY) | |
243 | return; | |
244 | /* | |
245 | * Check the remaining room for the input canonicalization | |
246 | * mode. We don't want to throttle the driver if we're in | |
247 | * canonical mode and don't have a newline yet! | |
248 | */ | |
249 | while (1) { | |
250 | int throttled; | |
251 | tty_set_flow_change(tty, TTY_THROTTLE_SAFE); | |
252 | if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE) | |
253 | break; | |
254 | throttled = tty_throttle_safe(tty); | |
255 | if (!throttled) | |
256 | break; | |
257 | } | |
258 | __tty_set_flow_change(tty, 0); | |
259 | } | |
260 | ||
261 | static inline void n_tty_check_unthrottle(struct tty_struct *tty) | |
262 | { | |
263 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY && | |
264 | tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) { | |
265 | if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE) | |
266 | return; | |
267 | if (!tty->count) | |
268 | return; | |
269 | n_tty_set_room(tty); | |
270 | n_tty_write_wakeup(tty->link); | |
271 | wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT); | |
272 | return; | |
273 | } | |
274 | ||
275 | /* If there is enough space in the read buffer now, let the | |
276 | * low-level driver know. We use chars_in_buffer() to | |
277 | * check the buffer, as it now knows about canonical mode. | |
278 | * Otherwise, if the driver is throttled and the line is | |
279 | * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode, | |
280 | * we won't get any more characters. | |
281 | */ | |
282 | ||
283 | while (1) { | |
284 | int unthrottled; | |
285 | tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE); | |
286 | if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE) | |
287 | break; | |
288 | if (!tty->count) | |
289 | break; | |
290 | n_tty_set_room(tty); | |
291 | unthrottled = tty_unthrottle_safe(tty); | |
292 | if (!unthrottled) | |
293 | break; | |
294 | } | |
295 | __tty_set_flow_change(tty, 0); | |
296 | } | |
297 | ||
298 | /** | |
299 | * put_tty_queue - add character to tty | |
300 | * @c: character | |
301 | * @ldata: n_tty data | |
302 | * | |
303 | * Add a character to the tty read_buf queue. | |
304 | * | |
305 | * n_tty_receive_buf()/producer path: | |
306 | * caller holds non-exclusive termios_rwsem | |
307 | * modifies read_head | |
308 | * | |
309 | * read_head is only considered 'published' if canonical mode is | |
310 | * not active. | |
311 | */ | |
312 | ||
313 | static void put_tty_queue(unsigned char c, struct n_tty_data *ldata) | |
314 | { | |
315 | if (read_cnt(ldata) < N_TTY_BUF_SIZE) { | |
316 | *read_buf_addr(ldata, ldata->read_head) = c; | |
317 | ldata->read_head++; | |
318 | } | |
319 | } | |
320 | ||
321 | /** | |
322 | * reset_buffer_flags - reset buffer state | |
323 | * @tty: terminal to reset | |
324 | * | |
325 | * Reset the read buffer counters and clear the flags. | |
326 | * Called from n_tty_open() and n_tty_flush_buffer(). | |
327 | * | |
328 | * Locking: caller holds exclusive termios_rwsem | |
329 | * (or locking is not required) | |
330 | */ | |
331 | ||
332 | static void reset_buffer_flags(struct n_tty_data *ldata) | |
333 | { | |
334 | ldata->read_head = ldata->canon_head = ldata->read_tail = 0; | |
335 | ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0; | |
336 | ||
337 | ldata->erasing = 0; | |
338 | bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); | |
339 | } | |
340 | ||
341 | static void n_tty_packet_mode_flush(struct tty_struct *tty) | |
342 | { | |
343 | unsigned long flags; | |
344 | ||
345 | spin_lock_irqsave(&tty->ctrl_lock, flags); | |
346 | if (tty->link->packet) { | |
347 | tty->ctrl_status |= TIOCPKT_FLUSHREAD; | |
348 | wake_up_interruptible(&tty->link->read_wait); | |
349 | } | |
350 | spin_unlock_irqrestore(&tty->ctrl_lock, flags); | |
351 | } | |
352 | ||
353 | /** | |
354 | * n_tty_flush_buffer - clean input queue | |
355 | * @tty: terminal device | |
356 | * | |
357 | * Flush the input buffer. Called when the tty layer wants the | |
358 | * buffer flushed (eg at hangup) or when the N_TTY line discipline | |
359 | * internally has to clean the pending queue (for example some signals). | |
360 | * | |
361 | * Holds termios_rwsem to exclude producer/consumer while | |
362 | * buffer indices are reset. | |
363 | * | |
364 | * Locking: ctrl_lock, exclusive termios_rwsem | |
365 | */ | |
366 | ||
367 | static void n_tty_flush_buffer(struct tty_struct *tty) | |
368 | { | |
369 | down_write(&tty->termios_rwsem); | |
370 | reset_buffer_flags(tty->disc_data); | |
371 | n_tty_set_room(tty); | |
372 | ||
373 | if (tty->link) | |
374 | n_tty_packet_mode_flush(tty); | |
375 | up_write(&tty->termios_rwsem); | |
376 | } | |
377 | ||
378 | /** | |
379 | * n_tty_chars_in_buffer - report available bytes | |
380 | * @tty: tty device | |
381 | * | |
382 | * Report the number of characters buffered to be delivered to user | |
383 | * at this instant in time. | |
384 | * | |
385 | * Locking: exclusive termios_rwsem | |
386 | */ | |
387 | ||
388 | static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) | |
389 | { | |
390 | ssize_t n; | |
391 | ||
392 | WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__); | |
393 | ||
394 | down_write(&tty->termios_rwsem); | |
395 | n = chars_in_buffer(tty); | |
396 | up_write(&tty->termios_rwsem); | |
397 | return n; | |
398 | } | |
399 | ||
400 | /** | |
401 | * is_utf8_continuation - utf8 multibyte check | |
402 | * @c: byte to check | |
403 | * | |
404 | * Returns true if the utf8 character 'c' is a multibyte continuation | |
405 | * character. We use this to correctly compute the on screen size | |
406 | * of the character when printing | |
407 | */ | |
408 | ||
409 | static inline int is_utf8_continuation(unsigned char c) | |
410 | { | |
411 | return (c & 0xc0) == 0x80; | |
412 | } | |
413 | ||
414 | /** | |
415 | * is_continuation - multibyte check | |
416 | * @c: byte to check | |
417 | * | |
418 | * Returns true if the utf8 character 'c' is a multibyte continuation | |
419 | * character and the terminal is in unicode mode. | |
420 | */ | |
421 | ||
422 | static inline int is_continuation(unsigned char c, struct tty_struct *tty) | |
423 | { | |
424 | return I_IUTF8(tty) && is_utf8_continuation(c); | |
425 | } | |
426 | ||
427 | /** | |
428 | * do_output_char - output one character | |
429 | * @c: character (or partial unicode symbol) | |
430 | * @tty: terminal device | |
431 | * @space: space available in tty driver write buffer | |
432 | * | |
433 | * This is a helper function that handles one output character | |
434 | * (including special characters like TAB, CR, LF, etc.), | |
435 | * doing OPOST processing and putting the results in the | |
436 | * tty driver's write buffer. | |
437 | * | |
438 | * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY | |
439 | * and NLDLY. They simply aren't relevant in the world today. | |
440 | * If you ever need them, add them here. | |
441 | * | |
442 | * Returns the number of bytes of buffer space used or -1 if | |
443 | * no space left. | |
444 | * | |
445 | * Locking: should be called under the output_lock to protect | |
446 | * the column state and space left in the buffer | |
447 | */ | |
448 | ||
449 | static int do_output_char(unsigned char c, struct tty_struct *tty, int space) | |
450 | { | |
451 | struct n_tty_data *ldata = tty->disc_data; | |
452 | int spaces; | |
453 | ||
454 | if (!space) | |
455 | return -1; | |
456 | ||
457 | switch (c) { | |
458 | case '\n': | |
459 | if (O_ONLRET(tty)) | |
460 | ldata->column = 0; | |
461 | if (O_ONLCR(tty)) { | |
462 | if (space < 2) | |
463 | return -1; | |
464 | ldata->canon_column = ldata->column = 0; | |
465 | tty->ops->write(tty, "\r\n", 2); | |
466 | return 2; | |
467 | } | |
468 | ldata->canon_column = ldata->column; | |
469 | break; | |
470 | case '\r': | |
471 | if (O_ONOCR(tty) && ldata->column == 0) | |
472 | return 0; | |
473 | if (O_OCRNL(tty)) { | |
474 | c = '\n'; | |
475 | if (O_ONLRET(tty)) | |
476 | ldata->canon_column = ldata->column = 0; | |
477 | break; | |
478 | } | |
479 | ldata->canon_column = ldata->column = 0; | |
480 | break; | |
481 | case '\t': | |
482 | spaces = 8 - (ldata->column & 7); | |
483 | if (O_TABDLY(tty) == XTABS) { | |
484 | if (space < spaces) | |
485 | return -1; | |
486 | ldata->column += spaces; | |
487 | tty->ops->write(tty, " ", spaces); | |
488 | return spaces; | |
489 | } | |
490 | ldata->column += spaces; | |
491 | break; | |
492 | case '\b': | |
493 | if (ldata->column > 0) | |
494 | ldata->column--; | |
495 | break; | |
496 | default: | |
497 | if (!iscntrl(c)) { | |
498 | if (O_OLCUC(tty)) | |
499 | c = toupper(c); | |
500 | if (!is_continuation(c, tty)) | |
501 | ldata->column++; | |
502 | } | |
503 | break; | |
504 | } | |
505 | ||
506 | tty_put_char(tty, c); | |
507 | return 1; | |
508 | } | |
509 | ||
510 | /** | |
511 | * process_output - output post processor | |
512 | * @c: character (or partial unicode symbol) | |
513 | * @tty: terminal device | |
514 | * | |
515 | * Output one character with OPOST processing. | |
516 | * Returns -1 when the output device is full and the character | |
517 | * must be retried. | |
518 | * | |
519 | * Locking: output_lock to protect column state and space left | |
520 | * (also, this is called from n_tty_write under the | |
521 | * tty layer write lock) | |
522 | */ | |
523 | ||
524 | static int process_output(unsigned char c, struct tty_struct *tty) | |
525 | { | |
526 | struct n_tty_data *ldata = tty->disc_data; | |
527 | int space, retval; | |
528 | ||
529 | mutex_lock(&ldata->output_lock); | |
530 | ||
531 | space = tty_write_room(tty); | |
532 | retval = do_output_char(c, tty, space); | |
533 | ||
534 | mutex_unlock(&ldata->output_lock); | |
535 | if (retval < 0) | |
536 | return -1; | |
537 | else | |
538 | return 0; | |
539 | } | |
540 | ||
541 | /** | |
542 | * process_output_block - block post processor | |
543 | * @tty: terminal device | |
544 | * @buf: character buffer | |
545 | * @nr: number of bytes to output | |
546 | * | |
547 | * Output a block of characters with OPOST processing. | |
548 | * Returns the number of characters output. | |
549 | * | |
550 | * This path is used to speed up block console writes, among other | |
551 | * things when processing blocks of output data. It handles only | |
552 | * the simple cases normally found and helps to generate blocks of | |
553 | * symbols for the console driver and thus improve performance. | |
554 | * | |
555 | * Locking: output_lock to protect column state and space left | |
556 | * (also, this is called from n_tty_write under the | |
557 | * tty layer write lock) | |
558 | */ | |
559 | ||
560 | static ssize_t process_output_block(struct tty_struct *tty, | |
561 | const unsigned char *buf, unsigned int nr) | |
562 | { | |
563 | struct n_tty_data *ldata = tty->disc_data; | |
564 | int space; | |
565 | int i; | |
566 | const unsigned char *cp; | |
567 | ||
568 | mutex_lock(&ldata->output_lock); | |
569 | ||
570 | space = tty_write_room(tty); | |
571 | if (!space) { | |
572 | mutex_unlock(&ldata->output_lock); | |
573 | return 0; | |
574 | } | |
575 | if (nr > space) | |
576 | nr = space; | |
577 | ||
578 | for (i = 0, cp = buf; i < nr; i++, cp++) { | |
579 | unsigned char c = *cp; | |
580 | ||
581 | switch (c) { | |
582 | case '\n': | |
583 | if (O_ONLRET(tty)) | |
584 | ldata->column = 0; | |
585 | if (O_ONLCR(tty)) | |
586 | goto break_out; | |
587 | ldata->canon_column = ldata->column; | |
588 | break; | |
589 | case '\r': | |
590 | if (O_ONOCR(tty) && ldata->column == 0) | |
591 | goto break_out; | |
592 | if (O_OCRNL(tty)) | |
593 | goto break_out; | |
594 | ldata->canon_column = ldata->column = 0; | |
595 | break; | |
596 | case '\t': | |
597 | goto break_out; | |
598 | case '\b': | |
599 | if (ldata->column > 0) | |
600 | ldata->column--; | |
601 | break; | |
602 | default: | |
603 | if (!iscntrl(c)) { | |
604 | if (O_OLCUC(tty)) | |
605 | goto break_out; | |
606 | if (!is_continuation(c, tty)) | |
607 | ldata->column++; | |
608 | } | |
609 | break; | |
610 | } | |
611 | } | |
612 | break_out: | |
613 | i = tty->ops->write(tty, buf, i); | |
614 | ||
615 | mutex_unlock(&ldata->output_lock); | |
616 | return i; | |
617 | } | |
618 | ||
619 | /** | |
620 | * process_echoes - write pending echo characters | |
621 | * @tty: terminal device | |
622 | * | |
623 | * Write previously buffered echo (and other ldisc-generated) | |
624 | * characters to the tty. | |
625 | * | |
626 | * Characters generated by the ldisc (including echoes) need to | |
627 | * be buffered because the driver's write buffer can fill during | |
628 | * heavy program output. Echoing straight to the driver will | |
629 | * often fail under these conditions, causing lost characters and | |
630 | * resulting mismatches of ldisc state information. | |
631 | * | |
632 | * Since the ldisc state must represent the characters actually sent | |
633 | * to the driver at the time of the write, operations like certain | |
634 | * changes in column state are also saved in the buffer and executed | |
635 | * here. | |
636 | * | |
637 | * A circular fifo buffer is used so that the most recent characters | |
638 | * are prioritized. Also, when control characters are echoed with a | |
639 | * prefixed "^", the pair is treated atomically and thus not separated. | |
640 | * | |
641 | * Locking: callers must hold output_lock | |
642 | */ | |
643 | ||
644 | static void __process_echoes(struct tty_struct *tty) | |
645 | { | |
646 | struct n_tty_data *ldata = tty->disc_data; | |
647 | int space, nr; | |
648 | size_t tail; | |
649 | unsigned char c; | |
650 | ||
651 | space = tty_write_room(tty); | |
652 | ||
653 | tail = ldata->echo_tail; | |
654 | nr = ldata->echo_commit - ldata->echo_tail; | |
655 | while (nr > 0) { | |
656 | c = echo_buf(ldata, tail); | |
657 | if (c == ECHO_OP_START) { | |
658 | unsigned char op; | |
659 | int no_space_left = 0; | |
660 | ||
661 | /* | |
662 | * If the buffer byte is the start of a multi-byte | |
663 | * operation, get the next byte, which is either the | |
664 | * op code or a control character value. | |
665 | */ | |
666 | op = echo_buf(ldata, tail + 1); | |
667 | ||
668 | switch (op) { | |
669 | unsigned int num_chars, num_bs; | |
670 | ||
671 | case ECHO_OP_ERASE_TAB: | |
672 | num_chars = echo_buf(ldata, tail + 2); | |
673 | ||
674 | /* | |
675 | * Determine how many columns to go back | |
676 | * in order to erase the tab. | |
677 | * This depends on the number of columns | |
678 | * used by other characters within the tab | |
679 | * area. If this (modulo 8) count is from | |
680 | * the start of input rather than from a | |
681 | * previous tab, we offset by canon column. | |
682 | * Otherwise, tab spacing is normal. | |
683 | */ | |
684 | if (!(num_chars & 0x80)) | |
685 | num_chars += ldata->canon_column; | |
686 | num_bs = 8 - (num_chars & 7); | |
687 | ||
688 | if (num_bs > space) { | |
689 | no_space_left = 1; | |
690 | break; | |
691 | } | |
692 | space -= num_bs; | |
693 | while (num_bs--) { | |
694 | tty_put_char(tty, '\b'); | |
695 | if (ldata->column > 0) | |
696 | ldata->column--; | |
697 | } | |
698 | tail += 3; | |
699 | nr -= 3; | |
700 | break; | |
701 | ||
702 | case ECHO_OP_SET_CANON_COL: | |
703 | ldata->canon_column = ldata->column; | |
704 | tail += 2; | |
705 | nr -= 2; | |
706 | break; | |
707 | ||
708 | case ECHO_OP_MOVE_BACK_COL: | |
709 | if (ldata->column > 0) | |
710 | ldata->column--; | |
711 | tail += 2; | |
712 | nr -= 2; | |
713 | break; | |
714 | ||
715 | case ECHO_OP_START: | |
716 | /* This is an escaped echo op start code */ | |
717 | if (!space) { | |
718 | no_space_left = 1; | |
719 | break; | |
720 | } | |
721 | tty_put_char(tty, ECHO_OP_START); | |
722 | ldata->column++; | |
723 | space--; | |
724 | tail += 2; | |
725 | nr -= 2; | |
726 | break; | |
727 | ||
728 | default: | |
729 | /* | |
730 | * If the op is not a special byte code, | |
731 | * it is a ctrl char tagged to be echoed | |
732 | * as "^X" (where X is the letter | |
733 | * representing the control char). | |
734 | * Note that we must ensure there is | |
735 | * enough space for the whole ctrl pair. | |
736 | * | |
737 | */ | |
738 | if (space < 2) { | |
739 | no_space_left = 1; | |
740 | break; | |
741 | } | |
742 | tty_put_char(tty, '^'); | |
743 | tty_put_char(tty, op ^ 0100); | |
744 | ldata->column += 2; | |
745 | space -= 2; | |
746 | tail += 2; | |
747 | nr -= 2; | |
748 | } | |
749 | ||
750 | if (no_space_left) | |
751 | break; | |
752 | } else { | |
753 | if (O_OPOST(tty)) { | |
754 | int retval = do_output_char(c, tty, space); | |
755 | if (retval < 0) | |
756 | break; | |
757 | space -= retval; | |
758 | } else { | |
759 | if (!space) | |
760 | break; | |
761 | tty_put_char(tty, c); | |
762 | space -= 1; | |
763 | } | |
764 | tail += 1; | |
765 | nr -= 1; | |
766 | } | |
767 | } | |
768 | ||
769 | ldata->echo_tail = tail; | |
770 | } | |
771 | ||
772 | static void commit_echoes(struct tty_struct *tty) | |
773 | { | |
774 | struct n_tty_data *ldata = tty->disc_data; | |
775 | ||
776 | mutex_lock(&ldata->output_lock); | |
777 | ldata->echo_commit = ldata->echo_head; | |
778 | __process_echoes(tty); | |
779 | mutex_unlock(&ldata->output_lock); | |
780 | ||
781 | if (tty->ops->flush_chars) | |
782 | tty->ops->flush_chars(tty); | |
783 | } | |
784 | ||
785 | static void process_echoes(struct tty_struct *tty) | |
786 | { | |
787 | struct n_tty_data *ldata = tty->disc_data; | |
788 | ||
789 | if (!L_ECHO(tty) || ldata->echo_commit == ldata->echo_tail) | |
790 | return; | |
791 | ||
792 | mutex_lock(&ldata->output_lock); | |
793 | __process_echoes(tty); | |
794 | mutex_unlock(&ldata->output_lock); | |
795 | ||
796 | if (tty->ops->flush_chars) | |
797 | tty->ops->flush_chars(tty); | |
798 | } | |
799 | ||
800 | /** | |
801 | * add_echo_byte - add a byte to the echo buffer | |
802 | * @c: unicode byte to echo | |
803 | * @ldata: n_tty data | |
804 | * | |
805 | * Add a character or operation byte to the echo buffer. | |
806 | * | |
807 | * Locks: may claim output_lock to prevent concurrent modify of | |
808 | * echo_tail by process_echoes(). | |
809 | */ | |
810 | ||
811 | static void add_echo_byte(unsigned char c, struct n_tty_data *ldata) | |
812 | { | |
813 | if (ldata->echo_head - ldata->echo_tail == N_TTY_BUF_SIZE) { | |
814 | size_t head = ldata->echo_head; | |
815 | ||
816 | mutex_lock(&ldata->output_lock); | |
817 | /* | |
818 | * Since the buffer start position needs to be advanced, | |
819 | * be sure to step by a whole operation byte group. | |
820 | */ | |
821 | if (echo_buf(ldata, head) == ECHO_OP_START) { | |
822 | if (echo_buf(ldata, head + 1) == ECHO_OP_ERASE_TAB) | |
823 | ldata->echo_tail += 3; | |
824 | else | |
825 | ldata->echo_tail += 2; | |
826 | } else | |
827 | ldata->echo_tail++; | |
828 | mutex_unlock(&ldata->output_lock); | |
829 | } | |
830 | ||
831 | *echo_buf_addr(ldata, ldata->echo_head++) = c; | |
832 | } | |
833 | ||
834 | /** | |
835 | * echo_move_back_col - add operation to move back a column | |
836 | * @ldata: n_tty data | |
837 | * | |
838 | * Add an operation to the echo buffer to move back one column. | |
839 | */ | |
840 | ||
841 | static void echo_move_back_col(struct n_tty_data *ldata) | |
842 | { | |
843 | add_echo_byte(ECHO_OP_START, ldata); | |
844 | add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata); | |
845 | } | |
846 | ||
847 | /** | |
848 | * echo_set_canon_col - add operation to set the canon column | |
849 | * @ldata: n_tty data | |
850 | * | |
851 | * Add an operation to the echo buffer to set the canon column | |
852 | * to the current column. | |
853 | */ | |
854 | ||
855 | static void echo_set_canon_col(struct n_tty_data *ldata) | |
856 | { | |
857 | add_echo_byte(ECHO_OP_START, ldata); | |
858 | add_echo_byte(ECHO_OP_SET_CANON_COL, ldata); | |
859 | } | |
860 | ||
861 | /** | |
862 | * echo_erase_tab - add operation to erase a tab | |
863 | * @num_chars: number of character columns already used | |
864 | * @after_tab: true if num_chars starts after a previous tab | |
865 | * @ldata: n_tty data | |
866 | * | |
867 | * Add an operation to the echo buffer to erase a tab. | |
868 | * | |
869 | * Called by the eraser function, which knows how many character | |
870 | * columns have been used since either a previous tab or the start | |
871 | * of input. This information will be used later, along with | |
872 | * canon column (if applicable), to go back the correct number | |
873 | * of columns. | |
874 | */ | |
875 | ||
876 | static void echo_erase_tab(unsigned int num_chars, int after_tab, | |
877 | struct n_tty_data *ldata) | |
878 | { | |
879 | add_echo_byte(ECHO_OP_START, ldata); | |
880 | add_echo_byte(ECHO_OP_ERASE_TAB, ldata); | |
881 | ||
882 | /* We only need to know this modulo 8 (tab spacing) */ | |
883 | num_chars &= 7; | |
884 | ||
885 | /* Set the high bit as a flag if num_chars is after a previous tab */ | |
886 | if (after_tab) | |
887 | num_chars |= 0x80; | |
888 | ||
889 | add_echo_byte(num_chars, ldata); | |
890 | } | |
891 | ||
892 | /** | |
893 | * echo_char_raw - echo a character raw | |
894 | * @c: unicode byte to echo | |
895 | * @tty: terminal device | |
896 | * | |
897 | * Echo user input back onto the screen. This must be called only when | |
898 | * L_ECHO(tty) is true. Called from the driver receive_buf path. | |
899 | * | |
900 | * This variant does not treat control characters specially. | |
901 | */ | |
902 | ||
903 | static void echo_char_raw(unsigned char c, struct n_tty_data *ldata) | |
904 | { | |
905 | if (c == ECHO_OP_START) { | |
906 | add_echo_byte(ECHO_OP_START, ldata); | |
907 | add_echo_byte(ECHO_OP_START, ldata); | |
908 | } else { | |
909 | add_echo_byte(c, ldata); | |
910 | } | |
911 | } | |
912 | ||
913 | /** | |
914 | * echo_char - echo a character | |
915 | * @c: unicode byte to echo | |
916 | * @tty: terminal device | |
917 | * | |
918 | * Echo user input back onto the screen. This must be called only when | |
919 | * L_ECHO(tty) is true. Called from the driver receive_buf path. | |
920 | * | |
921 | * This variant tags control characters to be echoed as "^X" | |
922 | * (where X is the letter representing the control char). | |
923 | */ | |
924 | ||
925 | static void echo_char(unsigned char c, struct tty_struct *tty) | |
926 | { | |
927 | struct n_tty_data *ldata = tty->disc_data; | |
928 | ||
929 | if (c == ECHO_OP_START) { | |
930 | add_echo_byte(ECHO_OP_START, ldata); | |
931 | add_echo_byte(ECHO_OP_START, ldata); | |
932 | } else { | |
933 | if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') | |
934 | add_echo_byte(ECHO_OP_START, ldata); | |
935 | add_echo_byte(c, ldata); | |
936 | } | |
937 | } | |
938 | ||
939 | /** | |
940 | * finish_erasing - complete erase | |
941 | * @ldata: n_tty data | |
942 | */ | |
943 | ||
944 | static inline void finish_erasing(struct n_tty_data *ldata) | |
945 | { | |
946 | if (ldata->erasing) { | |
947 | echo_char_raw('/', ldata); | |
948 | ldata->erasing = 0; | |
949 | } | |
950 | } | |
951 | ||
952 | /** | |
953 | * eraser - handle erase function | |
954 | * @c: character input | |
955 | * @tty: terminal device | |
956 | * | |
957 | * Perform erase and necessary output when an erase character is | |
958 | * present in the stream from the driver layer. Handles the complexities | |
959 | * of UTF-8 multibyte symbols. | |
960 | * | |
961 | * n_tty_receive_buf()/producer path: | |
962 | * caller holds non-exclusive termios_rwsem | |
963 | * modifies read_head | |
964 | * | |
965 | * Modifying the read_head is not considered a publish in this context | |
966 | * because canonical mode is active -- only canon_head publishes | |
967 | */ | |
968 | ||
969 | static void eraser(unsigned char c, struct tty_struct *tty) | |
970 | { | |
971 | struct n_tty_data *ldata = tty->disc_data; | |
972 | enum { ERASE, WERASE, KILL } kill_type; | |
973 | size_t head; | |
974 | size_t cnt; | |
975 | int seen_alnums; | |
976 | ||
977 | if (ldata->read_head == ldata->canon_head) { | |
978 | /* process_output('\a', tty); */ /* what do you think? */ | |
979 | return; | |
980 | } | |
981 | if (c == ERASE_CHAR(tty)) | |
982 | kill_type = ERASE; | |
983 | else if (c == WERASE_CHAR(tty)) | |
984 | kill_type = WERASE; | |
985 | else { | |
986 | if (!L_ECHO(tty)) { | |
987 | ldata->read_head = ldata->canon_head; | |
988 | return; | |
989 | } | |
990 | if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { | |
991 | ldata->read_head = ldata->canon_head; | |
992 | finish_erasing(ldata); | |
993 | echo_char(KILL_CHAR(tty), tty); | |
994 | /* Add a newline if ECHOK is on and ECHOKE is off. */ | |
995 | if (L_ECHOK(tty)) | |
996 | echo_char_raw('\n', ldata); | |
997 | return; | |
998 | } | |
999 | kill_type = KILL; | |
1000 | } | |
1001 | ||
1002 | seen_alnums = 0; | |
1003 | while (ldata->read_head != ldata->canon_head) { | |
1004 | head = ldata->read_head; | |
1005 | ||
1006 | /* erase a single possibly multibyte character */ | |
1007 | do { | |
1008 | head--; | |
1009 | c = read_buf(ldata, head); | |
1010 | } while (is_continuation(c, tty) && head != ldata->canon_head); | |
1011 | ||
1012 | /* do not partially erase */ | |
1013 | if (is_continuation(c, tty)) | |
1014 | break; | |
1015 | ||
1016 | if (kill_type == WERASE) { | |
1017 | /* Equivalent to BSD's ALTWERASE. */ | |
1018 | if (isalnum(c) || c == '_') | |
1019 | seen_alnums++; | |
1020 | else if (seen_alnums) | |
1021 | break; | |
1022 | } | |
1023 | cnt = ldata->read_head - head; | |
1024 | ldata->read_head = head; | |
1025 | if (L_ECHO(tty)) { | |
1026 | if (L_ECHOPRT(tty)) { | |
1027 | if (!ldata->erasing) { | |
1028 | echo_char_raw('\\', ldata); | |
1029 | ldata->erasing = 1; | |
1030 | } | |
1031 | /* if cnt > 1, output a multi-byte character */ | |
1032 | echo_char(c, tty); | |
1033 | while (--cnt > 0) { | |
1034 | head++; | |
1035 | echo_char_raw(read_buf(ldata, head), ldata); | |
1036 | echo_move_back_col(ldata); | |
1037 | } | |
1038 | } else if (kill_type == ERASE && !L_ECHOE(tty)) { | |
1039 | echo_char(ERASE_CHAR(tty), tty); | |
1040 | } else if (c == '\t') { | |
1041 | unsigned int num_chars = 0; | |
1042 | int after_tab = 0; | |
1043 | size_t tail = ldata->read_head; | |
1044 | ||
1045 | /* | |
1046 | * Count the columns used for characters | |
1047 | * since the start of input or after a | |
1048 | * previous tab. | |
1049 | * This info is used to go back the correct | |
1050 | * number of columns. | |
1051 | */ | |
1052 | while (tail != ldata->canon_head) { | |
1053 | tail--; | |
1054 | c = read_buf(ldata, tail); | |
1055 | if (c == '\t') { | |
1056 | after_tab = 1; | |
1057 | break; | |
1058 | } else if (iscntrl(c)) { | |
1059 | if (L_ECHOCTL(tty)) | |
1060 | num_chars += 2; | |
1061 | } else if (!is_continuation(c, tty)) { | |
1062 | num_chars++; | |
1063 | } | |
1064 | } | |
1065 | echo_erase_tab(num_chars, after_tab, ldata); | |
1066 | } else { | |
1067 | if (iscntrl(c) && L_ECHOCTL(tty)) { | |
1068 | echo_char_raw('\b', ldata); | |
1069 | echo_char_raw(' ', ldata); | |
1070 | echo_char_raw('\b', ldata); | |
1071 | } | |
1072 | if (!iscntrl(c) || L_ECHOCTL(tty)) { | |
1073 | echo_char_raw('\b', ldata); | |
1074 | echo_char_raw(' ', ldata); | |
1075 | echo_char_raw('\b', ldata); | |
1076 | } | |
1077 | } | |
1078 | } | |
1079 | if (kill_type == ERASE) | |
1080 | break; | |
1081 | } | |
1082 | if (ldata->read_head == ldata->canon_head && L_ECHO(tty)) | |
1083 | finish_erasing(ldata); | |
1084 | } | |
1085 | ||
1086 | /** | |
1087 | * isig - handle the ISIG optio | |
1088 | * @sig: signal | |
1089 | * @tty: terminal | |
1090 | * | |
1091 | * Called when a signal is being sent due to terminal input. | |
1092 | * Called from the driver receive_buf path so serialized. | |
1093 | * | |
1094 | * Locking: ctrl_lock | |
1095 | */ | |
1096 | ||
1097 | static inline void isig(int sig, struct tty_struct *tty) | |
1098 | { | |
1099 | struct pid *tty_pgrp = tty_get_pgrp(tty); | |
1100 | if (tty_pgrp) { | |
1101 | kill_pgrp(tty_pgrp, sig, 1); | |
1102 | put_pid(tty_pgrp); | |
1103 | } | |
1104 | } | |
1105 | ||
1106 | /** | |
1107 | * n_tty_receive_break - handle break | |
1108 | * @tty: terminal | |
1109 | * | |
1110 | * An RS232 break event has been hit in the incoming bitstream. This | |
1111 | * can cause a variety of events depending upon the termios settings. | |
1112 | * | |
1113 | * n_tty_receive_buf()/producer path: | |
1114 | * caller holds non-exclusive termios_rwsem | |
1115 | * publishes read_head via put_tty_queue() | |
1116 | * | |
1117 | * Note: may get exclusive termios_rwsem if flushing input buffer | |
1118 | */ | |
1119 | ||
1120 | static inline void n_tty_receive_break(struct tty_struct *tty) | |
1121 | { | |
1122 | struct n_tty_data *ldata = tty->disc_data; | |
1123 | ||
1124 | if (I_IGNBRK(tty)) | |
1125 | return; | |
1126 | if (I_BRKINT(tty)) { | |
1127 | isig(SIGINT, tty); | |
1128 | if (!L_NOFLSH(tty)) { | |
1129 | /* flushing needs exclusive termios_rwsem */ | |
1130 | up_read(&tty->termios_rwsem); | |
1131 | n_tty_flush_buffer(tty); | |
1132 | tty_driver_flush_buffer(tty); | |
1133 | down_read(&tty->termios_rwsem); | |
1134 | } | |
1135 | return; | |
1136 | } | |
1137 | if (I_PARMRK(tty)) { | |
1138 | put_tty_queue('\377', ldata); | |
1139 | put_tty_queue('\0', ldata); | |
1140 | } | |
1141 | put_tty_queue('\0', ldata); | |
1142 | wake_up_interruptible(&tty->read_wait); | |
1143 | } | |
1144 | ||
1145 | /** | |
1146 | * n_tty_receive_overrun - handle overrun reporting | |
1147 | * @tty: terminal | |
1148 | * | |
1149 | * Data arrived faster than we could process it. While the tty | |
1150 | * driver has flagged this the bits that were missed are gone | |
1151 | * forever. | |
1152 | * | |
1153 | * Called from the receive_buf path so single threaded. Does not | |
1154 | * need locking as num_overrun and overrun_time are function | |
1155 | * private. | |
1156 | */ | |
1157 | ||
1158 | static inline void n_tty_receive_overrun(struct tty_struct *tty) | |
1159 | { | |
1160 | struct n_tty_data *ldata = tty->disc_data; | |
1161 | char buf[64]; | |
1162 | ||
1163 | ldata->num_overrun++; | |
1164 | if (time_after(jiffies, ldata->overrun_time + HZ) || | |
1165 | time_after(ldata->overrun_time, jiffies)) { | |
1166 | printk(KERN_WARNING "%s: %d input overrun(s)\n", | |
1167 | tty_name(tty, buf), | |
1168 | ldata->num_overrun); | |
1169 | ldata->overrun_time = jiffies; | |
1170 | ldata->num_overrun = 0; | |
1171 | } | |
1172 | } | |
1173 | ||
1174 | /** | |
1175 | * n_tty_receive_parity_error - error notifier | |
1176 | * @tty: terminal device | |
1177 | * @c: character | |
1178 | * | |
1179 | * Process a parity error and queue the right data to indicate | |
1180 | * the error case if necessary. | |
1181 | * | |
1182 | * n_tty_receive_buf()/producer path: | |
1183 | * caller holds non-exclusive termios_rwsem | |
1184 | * publishes read_head via put_tty_queue() | |
1185 | */ | |
1186 | static inline void n_tty_receive_parity_error(struct tty_struct *tty, | |
1187 | unsigned char c) | |
1188 | { | |
1189 | struct n_tty_data *ldata = tty->disc_data; | |
1190 | ||
1191 | if (I_IGNPAR(tty)) | |
1192 | return; | |
1193 | if (I_PARMRK(tty)) { | |
1194 | put_tty_queue('\377', ldata); | |
1195 | put_tty_queue('\0', ldata); | |
1196 | put_tty_queue(c, ldata); | |
1197 | } else if (I_INPCK(tty)) | |
1198 | put_tty_queue('\0', ldata); | |
1199 | else | |
1200 | put_tty_queue(c, ldata); | |
1201 | wake_up_interruptible(&tty->read_wait); | |
1202 | } | |
1203 | ||
1204 | /** | |
1205 | * n_tty_receive_char - perform processing | |
1206 | * @tty: terminal device | |
1207 | * @c: character | |
1208 | * | |
1209 | * Process an individual character of input received from the driver. | |
1210 | * This is serialized with respect to itself by the rules for the | |
1211 | * driver above. | |
1212 | * | |
1213 | * n_tty_receive_buf()/producer path: | |
1214 | * caller holds non-exclusive termios_rwsem | |
1215 | * publishes canon_head if canonical mode is active | |
1216 | * otherwise, publishes read_head via put_tty_queue() | |
1217 | */ | |
1218 | ||
1219 | static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) | |
1220 | { | |
1221 | struct n_tty_data *ldata = tty->disc_data; | |
1222 | int parmrk; | |
1223 | ||
1224 | if (ldata->raw) { | |
1225 | put_tty_queue(c, ldata); | |
1226 | return; | |
1227 | } | |
1228 | ||
1229 | if (I_ISTRIP(tty)) | |
1230 | c &= 0x7f; | |
1231 | if (I_IUCLC(tty) && L_IEXTEN(tty)) | |
1232 | c = tolower(c); | |
1233 | ||
1234 | if (L_EXTPROC(tty)) { | |
1235 | put_tty_queue(c, ldata); | |
1236 | return; | |
1237 | } | |
1238 | ||
1239 | if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && | |
1240 | I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) && | |
1241 | c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) { | |
1242 | start_tty(tty); | |
1243 | process_echoes(tty); | |
1244 | } | |
1245 | ||
1246 | if (tty->closing) { | |
1247 | if (I_IXON(tty)) { | |
1248 | if (c == START_CHAR(tty)) { | |
1249 | start_tty(tty); | |
1250 | process_echoes(tty); | |
1251 | } else if (c == STOP_CHAR(tty)) | |
1252 | stop_tty(tty); | |
1253 | } | |
1254 | return; | |
1255 | } | |
1256 | ||
1257 | /* | |
1258 | * If the previous character was LNEXT, or we know that this | |
1259 | * character is not one of the characters that we'll have to | |
1260 | * handle specially, do shortcut processing to speed things | |
1261 | * up. | |
1262 | */ | |
1263 | if (!test_bit(c, ldata->process_char_map) || ldata->lnext) { | |
1264 | ldata->lnext = 0; | |
1265 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; | |
1266 | if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) { | |
1267 | /* beep if no space */ | |
1268 | if (L_ECHO(tty)) | |
1269 | process_output('\a', tty); | |
1270 | return; | |
1271 | } | |
1272 | if (L_ECHO(tty)) { | |
1273 | finish_erasing(ldata); | |
1274 | /* Record the column of first canon char. */ | |
1275 | if (ldata->canon_head == ldata->read_head) | |
1276 | echo_set_canon_col(ldata); | |
1277 | echo_char(c, tty); | |
1278 | commit_echoes(tty); | |
1279 | } | |
1280 | if (parmrk) | |
1281 | put_tty_queue(c, ldata); | |
1282 | put_tty_queue(c, ldata); | |
1283 | return; | |
1284 | } | |
1285 | ||
1286 | if (I_IXON(tty)) { | |
1287 | if (c == START_CHAR(tty)) { | |
1288 | start_tty(tty); | |
1289 | commit_echoes(tty); | |
1290 | return; | |
1291 | } | |
1292 | if (c == STOP_CHAR(tty)) { | |
1293 | stop_tty(tty); | |
1294 | return; | |
1295 | } | |
1296 | } | |
1297 | ||
1298 | if (L_ISIG(tty)) { | |
1299 | int signal; | |
1300 | signal = SIGINT; | |
1301 | if (c == INTR_CHAR(tty)) | |
1302 | goto send_signal; | |
1303 | signal = SIGQUIT; | |
1304 | if (c == QUIT_CHAR(tty)) | |
1305 | goto send_signal; | |
1306 | signal = SIGTSTP; | |
1307 | if (c == SUSP_CHAR(tty)) { | |
1308 | send_signal: | |
1309 | if (!L_NOFLSH(tty)) { | |
1310 | /* flushing needs exclusive termios_rwsem */ | |
1311 | up_read(&tty->termios_rwsem); | |
1312 | n_tty_flush_buffer(tty); | |
1313 | tty_driver_flush_buffer(tty); | |
1314 | down_read(&tty->termios_rwsem); | |
1315 | } | |
1316 | if (I_IXON(tty)) | |
1317 | start_tty(tty); | |
1318 | if (L_ECHO(tty)) { | |
1319 | echo_char(c, tty); | |
1320 | commit_echoes(tty); | |
1321 | } | |
1322 | isig(signal, tty); | |
1323 | return; | |
1324 | } | |
1325 | } | |
1326 | ||
1327 | if (c == '\r') { | |
1328 | if (I_IGNCR(tty)) | |
1329 | return; | |
1330 | if (I_ICRNL(tty)) | |
1331 | c = '\n'; | |
1332 | } else if (c == '\n' && I_INLCR(tty)) | |
1333 | c = '\r'; | |
1334 | ||
1335 | if (ldata->icanon) { | |
1336 | if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || | |
1337 | (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { | |
1338 | eraser(c, tty); | |
1339 | commit_echoes(tty); | |
1340 | return; | |
1341 | } | |
1342 | if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { | |
1343 | ldata->lnext = 1; | |
1344 | if (L_ECHO(tty)) { | |
1345 | finish_erasing(ldata); | |
1346 | if (L_ECHOCTL(tty)) { | |
1347 | echo_char_raw('^', ldata); | |
1348 | echo_char_raw('\b', ldata); | |
1349 | commit_echoes(tty); | |
1350 | } | |
1351 | } | |
1352 | return; | |
1353 | } | |
1354 | if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && | |
1355 | L_IEXTEN(tty)) { | |
1356 | size_t tail = ldata->canon_head; | |
1357 | ||
1358 | finish_erasing(ldata); | |
1359 | echo_char(c, tty); | |
1360 | echo_char_raw('\n', ldata); | |
1361 | while (tail != ldata->read_head) { | |
1362 | echo_char(read_buf(ldata, tail), tty); | |
1363 | tail++; | |
1364 | } | |
1365 | commit_echoes(tty); | |
1366 | return; | |
1367 | } | |
1368 | if (c == '\n') { | |
1369 | if (read_cnt(ldata) >= N_TTY_BUF_SIZE) { | |
1370 | if (L_ECHO(tty)) | |
1371 | process_output('\a', tty); | |
1372 | return; | |
1373 | } | |
1374 | if (L_ECHO(tty) || L_ECHONL(tty)) { | |
1375 | echo_char_raw('\n', ldata); | |
1376 | commit_echoes(tty); | |
1377 | } | |
1378 | goto handle_newline; | |
1379 | } | |
1380 | if (c == EOF_CHAR(tty)) { | |
1381 | if (read_cnt(ldata) >= N_TTY_BUF_SIZE) | |
1382 | return; | |
1383 | if (ldata->canon_head != ldata->read_head) | |
1384 | set_bit(TTY_PUSH, &tty->flags); | |
1385 | c = __DISABLED_CHAR; | |
1386 | goto handle_newline; | |
1387 | } | |
1388 | if ((c == EOL_CHAR(tty)) || | |
1389 | (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) { | |
1390 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) | |
1391 | ? 1 : 0; | |
1392 | if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk)) { | |
1393 | if (L_ECHO(tty)) | |
1394 | process_output('\a', tty); | |
1395 | return; | |
1396 | } | |
1397 | /* | |
1398 | * XXX are EOL_CHAR and EOL2_CHAR echoed?!? | |
1399 | */ | |
1400 | if (L_ECHO(tty)) { | |
1401 | /* Record the column of first canon char. */ | |
1402 | if (ldata->canon_head == ldata->read_head) | |
1403 | echo_set_canon_col(ldata); | |
1404 | echo_char(c, tty); | |
1405 | commit_echoes(tty); | |
1406 | } | |
1407 | /* | |
1408 | * XXX does PARMRK doubling happen for | |
1409 | * EOL_CHAR and EOL2_CHAR? | |
1410 | */ | |
1411 | if (parmrk) | |
1412 | put_tty_queue(c, ldata); | |
1413 | ||
1414 | handle_newline: | |
1415 | set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags); | |
1416 | put_tty_queue(c, ldata); | |
1417 | ldata->canon_head = ldata->read_head; | |
1418 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); | |
1419 | if (waitqueue_active(&tty->read_wait)) | |
1420 | wake_up_interruptible(&tty->read_wait); | |
1421 | return; | |
1422 | } | |
1423 | } | |
1424 | ||
1425 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; | |
1426 | if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) { | |
1427 | /* beep if no space */ | |
1428 | if (L_ECHO(tty)) | |
1429 | process_output('\a', tty); | |
1430 | return; | |
1431 | } | |
1432 | if (L_ECHO(tty)) { | |
1433 | finish_erasing(ldata); | |
1434 | if (c == '\n') | |
1435 | echo_char_raw('\n', ldata); | |
1436 | else { | |
1437 | /* Record the column of first canon char. */ | |
1438 | if (ldata->canon_head == ldata->read_head) | |
1439 | echo_set_canon_col(ldata); | |
1440 | echo_char(c, tty); | |
1441 | } | |
1442 | commit_echoes(tty); | |
1443 | } | |
1444 | ||
1445 | if (parmrk) | |
1446 | put_tty_queue(c, ldata); | |
1447 | ||
1448 | put_tty_queue(c, ldata); | |
1449 | } | |
1450 | ||
1451 | /** | |
1452 | * n_tty_receive_buf - data receive | |
1453 | * @tty: terminal device | |
1454 | * @cp: buffer | |
1455 | * @fp: flag buffer | |
1456 | * @count: characters | |
1457 | * | |
1458 | * Called by the terminal driver when a block of characters has | |
1459 | * been received. This function must be called from soft contexts | |
1460 | * not from interrupt context. The driver is responsible for making | |
1461 | * calls one at a time and in order (or using flush_to_ldisc) | |
1462 | * | |
1463 | * n_tty_receive_buf()/producer path: | |
1464 | * claims non-exclusive termios_rwsem | |
1465 | * publishes read_head and canon_head | |
1466 | */ | |
1467 | ||
1468 | static void __receive_buf(struct tty_struct *tty, const unsigned char *cp, | |
1469 | char *fp, int count) | |
1470 | { | |
1471 | struct n_tty_data *ldata = tty->disc_data; | |
1472 | const unsigned char *p; | |
1473 | char *f, flags = TTY_NORMAL; | |
1474 | char buf[64]; | |
1475 | ||
1476 | if (ldata->real_raw) { | |
1477 | size_t n, head; | |
1478 | ||
1479 | head = ldata->read_head & (N_TTY_BUF_SIZE - 1); | |
1480 | n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head); | |
1481 | n = min_t(size_t, count, n); | |
1482 | memcpy(read_buf_addr(ldata, head), cp, n); | |
1483 | ldata->read_head += n; | |
1484 | cp += n; | |
1485 | count -= n; | |
1486 | ||
1487 | head = ldata->read_head & (N_TTY_BUF_SIZE - 1); | |
1488 | n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head); | |
1489 | n = min_t(size_t, count, n); | |
1490 | memcpy(read_buf_addr(ldata, head), cp, n); | |
1491 | ldata->read_head += n; | |
1492 | } else { | |
1493 | int i; | |
1494 | ||
1495 | for (i = count, p = cp, f = fp; i; i--, p++) { | |
1496 | if (f) | |
1497 | flags = *f++; | |
1498 | switch (flags) { | |
1499 | case TTY_NORMAL: | |
1500 | n_tty_receive_char(tty, *p); | |
1501 | break; | |
1502 | case TTY_BREAK: | |
1503 | n_tty_receive_break(tty); | |
1504 | break; | |
1505 | case TTY_PARITY: | |
1506 | case TTY_FRAME: | |
1507 | n_tty_receive_parity_error(tty, *p); | |
1508 | break; | |
1509 | case TTY_OVERRUN: | |
1510 | n_tty_receive_overrun(tty); | |
1511 | break; | |
1512 | default: | |
1513 | printk(KERN_ERR "%s: unknown flag %d\n", | |
1514 | tty_name(tty, buf), flags); | |
1515 | break; | |
1516 | } | |
1517 | } | |
1518 | if (tty->ops->flush_chars) | |
1519 | tty->ops->flush_chars(tty); | |
1520 | } | |
1521 | ||
1522 | if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) || | |
1523 | L_EXTPROC(tty)) { | |
1524 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); | |
1525 | if (waitqueue_active(&tty->read_wait)) | |
1526 | wake_up_interruptible(&tty->read_wait); | |
1527 | } | |
1528 | ||
1529 | n_tty_check_throttle(tty); | |
1530 | } | |
1531 | ||
1532 | static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, | |
1533 | char *fp, int count) | |
1534 | { | |
1535 | down_read(&tty->termios_rwsem); | |
1536 | __receive_buf(tty, cp, fp, count); | |
1537 | up_read(&tty->termios_rwsem); | |
1538 | } | |
1539 | ||
1540 | static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp, | |
1541 | char *fp, int count) | |
1542 | { | |
1543 | struct n_tty_data *ldata = tty->disc_data; | |
1544 | int room; | |
1545 | ||
1546 | down_read(&tty->termios_rwsem); | |
1547 | ||
1548 | tty->receive_room = room = receive_room(tty); | |
1549 | if (!room) | |
1550 | ldata->no_room = 1; | |
1551 | count = min(count, room); | |
1552 | if (count) | |
1553 | __receive_buf(tty, cp, fp, count); | |
1554 | ||
1555 | up_read(&tty->termios_rwsem); | |
1556 | ||
1557 | return count; | |
1558 | } | |
1559 | ||
1560 | int is_ignored(int sig) | |
1561 | { | |
1562 | return (sigismember(¤t->blocked, sig) || | |
1563 | current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); | |
1564 | } | |
1565 | ||
1566 | /** | |
1567 | * n_tty_set_termios - termios data changed | |
1568 | * @tty: terminal | |
1569 | * @old: previous data | |
1570 | * | |
1571 | * Called by the tty layer when the user changes termios flags so | |
1572 | * that the line discipline can plan ahead. This function cannot sleep | |
1573 | * and is protected from re-entry by the tty layer. The user is | |
1574 | * guaranteed that this function will not be re-entered or in progress | |
1575 | * when the ldisc is closed. | |
1576 | * | |
1577 | * Locking: Caller holds tty->termios_rwsem | |
1578 | */ | |
1579 | ||
1580 | static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) | |
1581 | { | |
1582 | struct n_tty_data *ldata = tty->disc_data; | |
1583 | int canon_change = 1; | |
1584 | ||
1585 | if (old) | |
1586 | canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON; | |
1587 | if (canon_change) { | |
1588 | bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); | |
1589 | ldata->canon_head = ldata->read_tail; | |
1590 | ldata->erasing = 0; | |
1591 | ldata->lnext = 0; | |
1592 | } | |
1593 | ||
1594 | if (canon_change && !L_ICANON(tty) && read_cnt(ldata)) | |
1595 | wake_up_interruptible(&tty->read_wait); | |
1596 | ||
1597 | ldata->icanon = (L_ICANON(tty) != 0); | |
1598 | ||
1599 | if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) || | |
1600 | I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) || | |
1601 | I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) || | |
1602 | I_PARMRK(tty)) { | |
1603 | bitmap_zero(ldata->process_char_map, 256); | |
1604 | ||
1605 | if (I_IGNCR(tty) || I_ICRNL(tty)) | |
1606 | set_bit('\r', ldata->process_char_map); | |
1607 | if (I_INLCR(tty)) | |
1608 | set_bit('\n', ldata->process_char_map); | |
1609 | ||
1610 | if (L_ICANON(tty)) { | |
1611 | set_bit(ERASE_CHAR(tty), ldata->process_char_map); | |
1612 | set_bit(KILL_CHAR(tty), ldata->process_char_map); | |
1613 | set_bit(EOF_CHAR(tty), ldata->process_char_map); | |
1614 | set_bit('\n', ldata->process_char_map); | |
1615 | set_bit(EOL_CHAR(tty), ldata->process_char_map); | |
1616 | if (L_IEXTEN(tty)) { | |
1617 | set_bit(WERASE_CHAR(tty), | |
1618 | ldata->process_char_map); | |
1619 | set_bit(LNEXT_CHAR(tty), | |
1620 | ldata->process_char_map); | |
1621 | set_bit(EOL2_CHAR(tty), | |
1622 | ldata->process_char_map); | |
1623 | if (L_ECHO(tty)) | |
1624 | set_bit(REPRINT_CHAR(tty), | |
1625 | ldata->process_char_map); | |
1626 | } | |
1627 | } | |
1628 | if (I_IXON(tty)) { | |
1629 | set_bit(START_CHAR(tty), ldata->process_char_map); | |
1630 | set_bit(STOP_CHAR(tty), ldata->process_char_map); | |
1631 | } | |
1632 | if (L_ISIG(tty)) { | |
1633 | set_bit(INTR_CHAR(tty), ldata->process_char_map); | |
1634 | set_bit(QUIT_CHAR(tty), ldata->process_char_map); | |
1635 | set_bit(SUSP_CHAR(tty), ldata->process_char_map); | |
1636 | } | |
1637 | clear_bit(__DISABLED_CHAR, ldata->process_char_map); | |
1638 | ldata->raw = 0; | |
1639 | ldata->real_raw = 0; | |
1640 | } else { | |
1641 | ldata->raw = 1; | |
1642 | if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) && | |
1643 | (I_IGNPAR(tty) || !I_INPCK(tty)) && | |
1644 | (tty->driver->flags & TTY_DRIVER_REAL_RAW)) | |
1645 | ldata->real_raw = 1; | |
1646 | else | |
1647 | ldata->real_raw = 0; | |
1648 | } | |
1649 | n_tty_set_room(tty); | |
1650 | /* | |
1651 | * Fix tty hang when I_IXON(tty) is cleared, but the tty | |
1652 | * been stopped by STOP_CHAR(tty) before it. | |
1653 | */ | |
1654 | if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) { | |
1655 | start_tty(tty); | |
1656 | } | |
1657 | ||
1658 | /* The termios change make the tty ready for I/O */ | |
1659 | wake_up_interruptible(&tty->write_wait); | |
1660 | wake_up_interruptible(&tty->read_wait); | |
1661 | } | |
1662 | ||
1663 | /** | |
1664 | * n_tty_close - close the ldisc for this tty | |
1665 | * @tty: device | |
1666 | * | |
1667 | * Called from the terminal layer when this line discipline is | |
1668 | * being shut down, either because of a close or becsuse of a | |
1669 | * discipline change. The function will not be called while other | |
1670 | * ldisc methods are in progress. | |
1671 | */ | |
1672 | ||
1673 | static void n_tty_close(struct tty_struct *tty) | |
1674 | { | |
1675 | struct n_tty_data *ldata = tty->disc_data; | |
1676 | ||
1677 | if (tty->link) | |
1678 | n_tty_packet_mode_flush(tty); | |
1679 | ||
1680 | kfree(ldata->read_buf); | |
1681 | kfree(ldata->echo_buf); | |
1682 | kfree(ldata); | |
1683 | tty->disc_data = NULL; | |
1684 | } | |
1685 | ||
1686 | /** | |
1687 | * n_tty_open - open an ldisc | |
1688 | * @tty: terminal to open | |
1689 | * | |
1690 | * Called when this line discipline is being attached to the | |
1691 | * terminal device. Can sleep. Called serialized so that no | |
1692 | * other events will occur in parallel. No further open will occur | |
1693 | * until a close. | |
1694 | */ | |
1695 | ||
1696 | static int n_tty_open(struct tty_struct *tty) | |
1697 | { | |
1698 | struct n_tty_data *ldata; | |
1699 | ||
1700 | ldata = kzalloc(sizeof(*ldata), GFP_KERNEL); | |
1701 | if (!ldata) | |
1702 | goto err; | |
1703 | ||
1704 | ldata->overrun_time = jiffies; | |
1705 | mutex_init(&ldata->atomic_read_lock); | |
1706 | mutex_init(&ldata->output_lock); | |
1707 | ||
1708 | /* These are ugly. Currently a malloc failure here can panic */ | |
1709 | ldata->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); | |
1710 | ldata->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); | |
1711 | if (!ldata->read_buf || !ldata->echo_buf) | |
1712 | goto err_free_bufs; | |
1713 | ||
1714 | tty->disc_data = ldata; | |
1715 | reset_buffer_flags(tty->disc_data); | |
1716 | ldata->column = 0; | |
1717 | ldata->minimum_to_wake = 1; | |
1718 | tty->closing = 0; | |
1719 | /* indicate buffer work may resume */ | |
1720 | clear_bit(TTY_LDISC_HALTED, &tty->flags); | |
1721 | n_tty_set_termios(tty, NULL); | |
1722 | tty_unthrottle(tty); | |
1723 | ||
1724 | return 0; | |
1725 | err_free_bufs: | |
1726 | kfree(ldata->read_buf); | |
1727 | kfree(ldata->echo_buf); | |
1728 | kfree(ldata); | |
1729 | err: | |
1730 | return -ENOMEM; | |
1731 | } | |
1732 | ||
1733 | static inline int input_available_p(struct tty_struct *tty, int amt) | |
1734 | { | |
1735 | struct n_tty_data *ldata = tty->disc_data; | |
1736 | ||
1737 | if (ldata->icanon && !L_EXTPROC(tty)) { | |
1738 | if (ldata->canon_head != ldata->read_tail) | |
1739 | return 1; | |
1740 | } else if (read_cnt(ldata) >= (amt ? amt : 1)) | |
1741 | return 1; | |
1742 | ||
1743 | return 0; | |
1744 | } | |
1745 | ||
1746 | /** | |
1747 | * copy_from_read_buf - copy read data directly | |
1748 | * @tty: terminal device | |
1749 | * @b: user data | |
1750 | * @nr: size of data | |
1751 | * | |
1752 | * Helper function to speed up n_tty_read. It is only called when | |
1753 | * ICANON is off; it copies characters straight from the tty queue to | |
1754 | * user space directly. It can be profitably called twice; once to | |
1755 | * drain the space from the tail pointer to the (physical) end of the | |
1756 | * buffer, and once to drain the space from the (physical) beginning of | |
1757 | * the buffer to head pointer. | |
1758 | * | |
1759 | * Called under the ldata->atomic_read_lock sem | |
1760 | * | |
1761 | * n_tty_read()/consumer path: | |
1762 | * caller holds non-exclusive termios_rwsem | |
1763 | * read_tail published | |
1764 | */ | |
1765 | ||
1766 | static int copy_from_read_buf(struct tty_struct *tty, | |
1767 | unsigned char __user **b, | |
1768 | size_t *nr) | |
1769 | ||
1770 | { | |
1771 | struct n_tty_data *ldata = tty->disc_data; | |
1772 | int retval; | |
1773 | size_t n; | |
1774 | bool is_eof; | |
1775 | size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1); | |
1776 | ||
1777 | retval = 0; | |
1778 | n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail); | |
1779 | n = min(*nr, n); | |
1780 | if (n) { | |
1781 | retval = copy_to_user(*b, read_buf_addr(ldata, tail), n); | |
1782 | n -= retval; | |
1783 | is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty); | |
1784 | tty_audit_add_data(tty, read_buf_addr(ldata, tail), n, | |
1785 | ldata->icanon); | |
1786 | ldata->read_tail += n; | |
1787 | /* Turn single EOF into zero-length read */ | |
1788 | if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata)) | |
1789 | n = 0; | |
1790 | *b += n; | |
1791 | *nr -= n; | |
1792 | } | |
1793 | return retval; | |
1794 | } | |
1795 | ||
1796 | /** | |
1797 | * canon_copy_from_read_buf - copy read data in canonical mode | |
1798 | * @tty: terminal device | |
1799 | * @b: user data | |
1800 | * @nr: size of data | |
1801 | * | |
1802 | * Helper function for n_tty_read. It is only called when ICANON is on; | |
1803 | * it copies one line of input up to and including the line-delimiting | |
1804 | * character into the user-space buffer. | |
1805 | * | |
1806 | * Called under the atomic_read_lock mutex | |
1807 | * | |
1808 | * n_tty_read()/consumer path: | |
1809 | * caller holds non-exclusive termios_rwsem | |
1810 | * read_tail published | |
1811 | */ | |
1812 | ||
1813 | static int canon_copy_from_read_buf(struct tty_struct *tty, | |
1814 | unsigned char __user **b, | |
1815 | size_t *nr) | |
1816 | { | |
1817 | struct n_tty_data *ldata = tty->disc_data; | |
1818 | size_t n, size, more, c; | |
1819 | size_t eol; | |
1820 | size_t tail; | |
1821 | int ret, found = 0; | |
1822 | ||
1823 | /* N.B. avoid overrun if nr == 0 */ | |
1824 | n = min(*nr, read_cnt(ldata)); | |
1825 | if (!n) | |
1826 | return 0; | |
1827 | ||
1828 | tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1); | |
1829 | size = min_t(size_t, tail + n, N_TTY_BUF_SIZE); | |
1830 | ||
1831 | n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n", | |
1832 | __func__, *nr, tail, n, size); | |
1833 | ||
1834 | eol = find_next_bit(ldata->read_flags, size, tail); | |
1835 | more = n - (size - tail); | |
1836 | if (eol == N_TTY_BUF_SIZE && more) { | |
1837 | /* scan wrapped without finding set bit */ | |
1838 | eol = find_next_bit(ldata->read_flags, more, 0); | |
1839 | if (eol != more) | |
1840 | found = 1; | |
1841 | } else if (eol != size) | |
1842 | found = 1; | |
1843 | ||
1844 | size = N_TTY_BUF_SIZE - tail; | |
1845 | n = (found + eol + size) & (N_TTY_BUF_SIZE - 1); | |
1846 | c = n; | |
1847 | ||
1848 | if (found && read_buf(ldata, eol) == __DISABLED_CHAR) | |
1849 | n--; | |
1850 | ||
1851 | n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n", | |
1852 | __func__, eol, found, n, c, size, more); | |
1853 | ||
1854 | if (n > size) { | |
1855 | ret = copy_to_user(*b, read_buf_addr(ldata, tail), size); | |
1856 | if (ret) | |
1857 | return -EFAULT; | |
1858 | ret = copy_to_user(*b + size, ldata->read_buf, n - size); | |
1859 | } else | |
1860 | ret = copy_to_user(*b, read_buf_addr(ldata, tail), n); | |
1861 | ||
1862 | if (ret) | |
1863 | return -EFAULT; | |
1864 | *b += n; | |
1865 | *nr -= n; | |
1866 | ||
1867 | if (found) | |
1868 | clear_bit(eol, ldata->read_flags); | |
1869 | smp_mb__after_clear_bit(); | |
1870 | ldata->read_tail += c; | |
1871 | ||
1872 | if (found) | |
1873 | tty_audit_push(tty); | |
1874 | return 0; | |
1875 | } | |
1876 | ||
1877 | extern ssize_t redirected_tty_write(struct file *, const char __user *, | |
1878 | size_t, loff_t *); | |
1879 | ||
1880 | /** | |
1881 | * job_control - check job control | |
1882 | * @tty: tty | |
1883 | * @file: file handle | |
1884 | * | |
1885 | * Perform job control management checks on this file/tty descriptor | |
1886 | * and if appropriate send any needed signals and return a negative | |
1887 | * error code if action should be taken. | |
1888 | * | |
1889 | * Locking: redirected write test is safe | |
1890 | * current->signal->tty check is safe | |
1891 | * ctrl_lock to safely reference tty->pgrp | |
1892 | */ | |
1893 | ||
1894 | static int job_control(struct tty_struct *tty, struct file *file) | |
1895 | { | |
1896 | /* Job control check -- must be done at start and after | |
1897 | every sleep (POSIX.1 7.1.1.4). */ | |
1898 | /* NOTE: not yet done after every sleep pending a thorough | |
1899 | check of the logic of this change. -- jlc */ | |
1900 | /* don't stop on /dev/console */ | |
1901 | if (file->f_op->write == redirected_tty_write || | |
1902 | current->signal->tty != tty) | |
1903 | return 0; | |
1904 | ||
1905 | spin_lock_irq(&tty->ctrl_lock); | |
1906 | if (!tty->pgrp) | |
1907 | printk(KERN_ERR "n_tty_read: no tty->pgrp!\n"); | |
1908 | else if (task_pgrp(current) != tty->pgrp) { | |
1909 | spin_unlock_irq(&tty->ctrl_lock); | |
1910 | if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned()) | |
1911 | return -EIO; | |
1912 | kill_pgrp(task_pgrp(current), SIGTTIN, 1); | |
1913 | set_thread_flag(TIF_SIGPENDING); | |
1914 | return -ERESTARTSYS; | |
1915 | } | |
1916 | spin_unlock_irq(&tty->ctrl_lock); | |
1917 | return 0; | |
1918 | } | |
1919 | ||
1920 | ||
1921 | /** | |
1922 | * n_tty_read - read function for tty | |
1923 | * @tty: tty device | |
1924 | * @file: file object | |
1925 | * @buf: userspace buffer pointer | |
1926 | * @nr: size of I/O | |
1927 | * | |
1928 | * Perform reads for the line discipline. We are guaranteed that the | |
1929 | * line discipline will not be closed under us but we may get multiple | |
1930 | * parallel readers and must handle this ourselves. We may also get | |
1931 | * a hangup. Always called in user context, may sleep. | |
1932 | * | |
1933 | * This code must be sure never to sleep through a hangup. | |
1934 | * | |
1935 | * n_tty_read()/consumer path: | |
1936 | * claims non-exclusive termios_rwsem | |
1937 | * publishes read_tail | |
1938 | */ | |
1939 | ||
1940 | static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, | |
1941 | unsigned char __user *buf, size_t nr) | |
1942 | { | |
1943 | struct n_tty_data *ldata = tty->disc_data; | |
1944 | unsigned char __user *b = buf; | |
1945 | DECLARE_WAITQUEUE(wait, current); | |
1946 | int c; | |
1947 | int minimum, time; | |
1948 | ssize_t retval = 0; | |
1949 | ssize_t size; | |
1950 | long timeout; | |
1951 | unsigned long flags; | |
1952 | int packet; | |
1953 | ||
1954 | do_it_again: | |
1955 | c = job_control(tty, file); | |
1956 | if (c < 0) | |
1957 | return c; | |
1958 | ||
1959 | down_read(&tty->termios_rwsem); | |
1960 | ||
1961 | minimum = time = 0; | |
1962 | timeout = MAX_SCHEDULE_TIMEOUT; | |
1963 | if (!ldata->icanon) { | |
1964 | minimum = MIN_CHAR(tty); | |
1965 | if (minimum) { | |
1966 | time = (HZ / 10) * TIME_CHAR(tty); | |
1967 | if (time) | |
1968 | ldata->minimum_to_wake = 1; | |
1969 | else if (!waitqueue_active(&tty->read_wait) || | |
1970 | (ldata->minimum_to_wake > minimum)) | |
1971 | ldata->minimum_to_wake = minimum; | |
1972 | } else { | |
1973 | timeout = (HZ / 10) * TIME_CHAR(tty); | |
1974 | ldata->minimum_to_wake = minimum = 1; | |
1975 | } | |
1976 | } | |
1977 | ||
1978 | /* | |
1979 | * Internal serialization of reads. | |
1980 | */ | |
1981 | if (file->f_flags & O_NONBLOCK) { | |
1982 | if (!mutex_trylock(&ldata->atomic_read_lock)) { | |
1983 | up_read(&tty->termios_rwsem); | |
1984 | return -EAGAIN; | |
1985 | } | |
1986 | } else { | |
1987 | if (mutex_lock_interruptible(&ldata->atomic_read_lock)) { | |
1988 | up_read(&tty->termios_rwsem); | |
1989 | return -ERESTARTSYS; | |
1990 | } | |
1991 | } | |
1992 | packet = tty->packet; | |
1993 | ||
1994 | add_wait_queue(&tty->read_wait, &wait); | |
1995 | while (nr) { | |
1996 | /* First test for status change. */ | |
1997 | if (packet && tty->link->ctrl_status) { | |
1998 | unsigned char cs; | |
1999 | if (b != buf) | |
2000 | break; | |
2001 | spin_lock_irqsave(&tty->link->ctrl_lock, flags); | |
2002 | cs = tty->link->ctrl_status; | |
2003 | tty->link->ctrl_status = 0; | |
2004 | spin_unlock_irqrestore(&tty->link->ctrl_lock, flags); | |
2005 | if (tty_put_user(tty, cs, b++)) { | |
2006 | retval = -EFAULT; | |
2007 | b--; | |
2008 | break; | |
2009 | } | |
2010 | nr--; | |
2011 | break; | |
2012 | } | |
2013 | /* This statement must be first before checking for input | |
2014 | so that any interrupt will set the state back to | |
2015 | TASK_RUNNING. */ | |
2016 | set_current_state(TASK_INTERRUPTIBLE); | |
2017 | ||
2018 | if (((minimum - (b - buf)) < ldata->minimum_to_wake) && | |
2019 | ((minimum - (b - buf)) >= 1)) | |
2020 | ldata->minimum_to_wake = (minimum - (b - buf)); | |
2021 | ||
2022 | if (!input_available_p(tty, 0)) { | |
2023 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { | |
2024 | retval = -EIO; | |
2025 | break; | |
2026 | } | |
2027 | if (tty_hung_up_p(file)) | |
2028 | break; | |
2029 | if (!timeout) | |
2030 | break; | |
2031 | if (file->f_flags & O_NONBLOCK) { | |
2032 | retval = -EAGAIN; | |
2033 | break; | |
2034 | } | |
2035 | if (signal_pending(current)) { | |
2036 | retval = -ERESTARTSYS; | |
2037 | break; | |
2038 | } | |
2039 | n_tty_set_room(tty); | |
2040 | up_read(&tty->termios_rwsem); | |
2041 | ||
2042 | timeout = schedule_timeout(timeout); | |
2043 | ||
2044 | down_read(&tty->termios_rwsem); | |
2045 | continue; | |
2046 | } | |
2047 | __set_current_state(TASK_RUNNING); | |
2048 | ||
2049 | /* Deal with packet mode. */ | |
2050 | if (packet && b == buf) { | |
2051 | if (tty_put_user(tty, TIOCPKT_DATA, b++)) { | |
2052 | retval = -EFAULT; | |
2053 | b--; | |
2054 | break; | |
2055 | } | |
2056 | nr--; | |
2057 | } | |
2058 | ||
2059 | if (ldata->icanon && !L_EXTPROC(tty)) { | |
2060 | retval = canon_copy_from_read_buf(tty, &b, &nr); | |
2061 | if (retval) | |
2062 | break; | |
2063 | } else { | |
2064 | int uncopied; | |
2065 | /* The copy function takes the read lock and handles | |
2066 | locking internally for this case */ | |
2067 | uncopied = copy_from_read_buf(tty, &b, &nr); | |
2068 | uncopied += copy_from_read_buf(tty, &b, &nr); | |
2069 | if (uncopied) { | |
2070 | retval = -EFAULT; | |
2071 | break; | |
2072 | } | |
2073 | } | |
2074 | ||
2075 | n_tty_check_unthrottle(tty); | |
2076 | ||
2077 | if (b - buf >= minimum) | |
2078 | break; | |
2079 | if (time) | |
2080 | timeout = time; | |
2081 | } | |
2082 | mutex_unlock(&ldata->atomic_read_lock); | |
2083 | remove_wait_queue(&tty->read_wait, &wait); | |
2084 | ||
2085 | if (!waitqueue_active(&tty->read_wait)) | |
2086 | ldata->minimum_to_wake = minimum; | |
2087 | ||
2088 | __set_current_state(TASK_RUNNING); | |
2089 | size = b - buf; | |
2090 | if (size) { | |
2091 | retval = size; | |
2092 | if (nr) | |
2093 | clear_bit(TTY_PUSH, &tty->flags); | |
2094 | } else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) { | |
2095 | up_read(&tty->termios_rwsem); | |
2096 | goto do_it_again; | |
2097 | } | |
2098 | ||
2099 | n_tty_set_room(tty); | |
2100 | up_read(&tty->termios_rwsem); | |
2101 | return retval; | |
2102 | } | |
2103 | ||
2104 | /** | |
2105 | * n_tty_write - write function for tty | |
2106 | * @tty: tty device | |
2107 | * @file: file object | |
2108 | * @buf: userspace buffer pointer | |
2109 | * @nr: size of I/O | |
2110 | * | |
2111 | * Write function of the terminal device. This is serialized with | |
2112 | * respect to other write callers but not to termios changes, reads | |
2113 | * and other such events. Since the receive code will echo characters, | |
2114 | * thus calling driver write methods, the output_lock is used in | |
2115 | * the output processing functions called here as well as in the | |
2116 | * echo processing function to protect the column state and space | |
2117 | * left in the buffer. | |
2118 | * | |
2119 | * This code must be sure never to sleep through a hangup. | |
2120 | * | |
2121 | * Locking: output_lock to protect column state and space left | |
2122 | * (note that the process_output*() functions take this | |
2123 | * lock themselves) | |
2124 | */ | |
2125 | ||
2126 | static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, | |
2127 | const unsigned char *buf, size_t nr) | |
2128 | { | |
2129 | const unsigned char *b = buf; | |
2130 | DECLARE_WAITQUEUE(wait, current); | |
2131 | int c; | |
2132 | ssize_t retval = 0; | |
2133 | ||
2134 | /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ | |
2135 | if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) { | |
2136 | retval = tty_check_change(tty); | |
2137 | if (retval) | |
2138 | return retval; | |
2139 | } | |
2140 | ||
2141 | down_read(&tty->termios_rwsem); | |
2142 | ||
2143 | /* Write out any echoed characters that are still pending */ | |
2144 | process_echoes(tty); | |
2145 | ||
2146 | add_wait_queue(&tty->write_wait, &wait); | |
2147 | while (1) { | |
2148 | set_current_state(TASK_INTERRUPTIBLE); | |
2149 | if (signal_pending(current)) { | |
2150 | retval = -ERESTARTSYS; | |
2151 | break; | |
2152 | } | |
2153 | if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { | |
2154 | retval = -EIO; | |
2155 | break; | |
2156 | } | |
2157 | if (O_OPOST(tty)) { | |
2158 | while (nr > 0) { | |
2159 | ssize_t num = process_output_block(tty, b, nr); | |
2160 | if (num < 0) { | |
2161 | if (num == -EAGAIN) | |
2162 | break; | |
2163 | retval = num; | |
2164 | goto break_out; | |
2165 | } | |
2166 | b += num; | |
2167 | nr -= num; | |
2168 | if (nr == 0) | |
2169 | break; | |
2170 | c = *b; | |
2171 | if (process_output(c, tty) < 0) | |
2172 | break; | |
2173 | b++; nr--; | |
2174 | } | |
2175 | if (tty->ops->flush_chars) | |
2176 | tty->ops->flush_chars(tty); | |
2177 | } else { | |
2178 | while (nr > 0) { | |
2179 | c = tty->ops->write(tty, b, nr); | |
2180 | if (c < 0) { | |
2181 | retval = c; | |
2182 | goto break_out; | |
2183 | } | |
2184 | if (!c) | |
2185 | break; | |
2186 | b += c; | |
2187 | nr -= c; | |
2188 | } | |
2189 | } | |
2190 | if (!nr) | |
2191 | break; | |
2192 | if (file->f_flags & O_NONBLOCK) { | |
2193 | retval = -EAGAIN; | |
2194 | break; | |
2195 | } | |
2196 | up_read(&tty->termios_rwsem); | |
2197 | ||
2198 | schedule(); | |
2199 | ||
2200 | down_read(&tty->termios_rwsem); | |
2201 | } | |
2202 | break_out: | |
2203 | __set_current_state(TASK_RUNNING); | |
2204 | remove_wait_queue(&tty->write_wait, &wait); | |
2205 | if (b - buf != nr && tty->fasync) | |
2206 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); | |
2207 | up_read(&tty->termios_rwsem); | |
2208 | return (b - buf) ? b - buf : retval; | |
2209 | } | |
2210 | ||
2211 | /** | |
2212 | * n_tty_poll - poll method for N_TTY | |
2213 | * @tty: terminal device | |
2214 | * @file: file accessing it | |
2215 | * @wait: poll table | |
2216 | * | |
2217 | * Called when the line discipline is asked to poll() for data or | |
2218 | * for special events. This code is not serialized with respect to | |
2219 | * other events save open/close. | |
2220 | * | |
2221 | * This code must be sure never to sleep through a hangup. | |
2222 | * Called without the kernel lock held - fine | |
2223 | */ | |
2224 | ||
2225 | static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file, | |
2226 | poll_table *wait) | |
2227 | { | |
2228 | struct n_tty_data *ldata = tty->disc_data; | |
2229 | unsigned int mask = 0; | |
2230 | ||
2231 | poll_wait(file, &tty->read_wait, wait); | |
2232 | poll_wait(file, &tty->write_wait, wait); | |
2233 | if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty))) | |
2234 | mask |= POLLIN | POLLRDNORM; | |
2235 | if (tty->packet && tty->link->ctrl_status) | |
2236 | mask |= POLLPRI | POLLIN | POLLRDNORM; | |
2237 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
2238 | mask |= POLLHUP; | |
2239 | if (tty_hung_up_p(file)) | |
2240 | mask |= POLLHUP; | |
2241 | if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) { | |
2242 | if (MIN_CHAR(tty) && !TIME_CHAR(tty)) | |
2243 | ldata->minimum_to_wake = MIN_CHAR(tty); | |
2244 | else | |
2245 | ldata->minimum_to_wake = 1; | |
2246 | } | |
2247 | if (tty->ops->write && !tty_is_writelocked(tty) && | |
2248 | tty_chars_in_buffer(tty) < WAKEUP_CHARS && | |
2249 | tty_write_room(tty) > 0) | |
2250 | mask |= POLLOUT | POLLWRNORM; | |
2251 | return mask; | |
2252 | } | |
2253 | ||
2254 | static unsigned long inq_canon(struct n_tty_data *ldata) | |
2255 | { | |
2256 | size_t nr, head, tail; | |
2257 | ||
2258 | if (ldata->canon_head == ldata->read_tail) | |
2259 | return 0; | |
2260 | head = ldata->canon_head; | |
2261 | tail = ldata->read_tail; | |
2262 | nr = head - tail; | |
2263 | /* Skip EOF-chars.. */ | |
2264 | while (head != tail) { | |
2265 | if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) && | |
2266 | read_buf(ldata, tail) == __DISABLED_CHAR) | |
2267 | nr--; | |
2268 | tail++; | |
2269 | } | |
2270 | return nr; | |
2271 | } | |
2272 | ||
2273 | static int n_tty_ioctl(struct tty_struct *tty, struct file *file, | |
2274 | unsigned int cmd, unsigned long arg) | |
2275 | { | |
2276 | struct n_tty_data *ldata = tty->disc_data; | |
2277 | int retval; | |
2278 | ||
2279 | switch (cmd) { | |
2280 | case TIOCOUTQ: | |
2281 | return put_user(tty_chars_in_buffer(tty), (int __user *) arg); | |
2282 | case TIOCINQ: | |
2283 | down_write(&tty->termios_rwsem); | |
2284 | if (L_ICANON(tty)) | |
2285 | retval = inq_canon(ldata); | |
2286 | else | |
2287 | retval = read_cnt(ldata); | |
2288 | up_write(&tty->termios_rwsem); | |
2289 | return put_user(retval, (unsigned int __user *) arg); | |
2290 | default: | |
2291 | return n_tty_ioctl_helper(tty, file, cmd, arg); | |
2292 | } | |
2293 | } | |
2294 | ||
2295 | static void n_tty_fasync(struct tty_struct *tty, int on) | |
2296 | { | |
2297 | struct n_tty_data *ldata = tty->disc_data; | |
2298 | ||
2299 | if (!waitqueue_active(&tty->read_wait)) { | |
2300 | if (on) | |
2301 | ldata->minimum_to_wake = 1; | |
2302 | else if (!tty->fasync) | |
2303 | ldata->minimum_to_wake = N_TTY_BUF_SIZE; | |
2304 | } | |
2305 | } | |
2306 | ||
2307 | struct tty_ldisc_ops tty_ldisc_N_TTY = { | |
2308 | .magic = TTY_LDISC_MAGIC, | |
2309 | .name = "n_tty", | |
2310 | .open = n_tty_open, | |
2311 | .close = n_tty_close, | |
2312 | .flush_buffer = n_tty_flush_buffer, | |
2313 | .chars_in_buffer = n_tty_chars_in_buffer, | |
2314 | .read = n_tty_read, | |
2315 | .write = n_tty_write, | |
2316 | .ioctl = n_tty_ioctl, | |
2317 | .set_termios = n_tty_set_termios, | |
2318 | .poll = n_tty_poll, | |
2319 | .receive_buf = n_tty_receive_buf, | |
2320 | .write_wakeup = n_tty_write_wakeup, | |
2321 | .fasync = n_tty_fasync, | |
2322 | .receive_buf2 = n_tty_receive_buf2, | |
2323 | }; | |
2324 | ||
2325 | /** | |
2326 | * n_tty_inherit_ops - inherit N_TTY methods | |
2327 | * @ops: struct tty_ldisc_ops where to save N_TTY methods | |
2328 | * | |
2329 | * Enables a 'subclass' line discipline to 'inherit' N_TTY | |
2330 | * methods. | |
2331 | */ | |
2332 | ||
2333 | void n_tty_inherit_ops(struct tty_ldisc_ops *ops) | |
2334 | { | |
2335 | *ops = tty_ldisc_N_TTY; | |
2336 | ops->owner = NULL; | |
2337 | ops->refcount = ops->flags = 0; | |
2338 | } | |
2339 | EXPORT_SYMBOL_GPL(n_tty_inherit_ops); |