FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_inq.c
1 /*-
2 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Portions of this software were developed under sponsorship from Snow
6 * B.V., the Netherlands.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD: releng/11.2/sys/kern/tty_inq.c 314538 2017-03-02 04:23:53Z ian $");
32
33 #include <sys/param.h>
34 #include <sys/kernel.h>
35 #include <sys/lock.h>
36 #include <sys/queue.h>
37 #include <sys/sysctl.h>
38 #include <sys/systm.h>
39 #include <sys/tty.h>
40 #include <sys/uio.h>
41
42 #include <vm/uma.h>
43
44 /*
45 * TTY input queue buffering.
46 *
47 * Unlike the output queue, the input queue has more features that are
48 * needed to properly implement various features offered by the TTY
49 * interface:
50 *
51 * - Data can be removed from the tail of the queue, which is used to
52 * implement backspace.
53 * - Once in a while, input has to be `canonicalized'. When ICANON is
54 * turned on, this will be done after a CR has been inserted.
55 * Otherwise, it should be done after any character has been inserted.
56 * - The input queue can store one bit per byte, called the quoting bit.
57 * This bit is used by TTYDISC to make backspace work on quoted
58 * characters.
59 *
60 * In most cases, there is probably less input than output, so unlike
61 * the outq, we'll stick to 128 byte blocks here.
62 */
63
64 static int ttyinq_flush_secure = 1;
65 SYSCTL_INT(_kern, OID_AUTO, tty_inq_flush_secure, CTLFLAG_RW,
66 &ttyinq_flush_secure, 0, "Zero buffers while flushing");
67
68 #define TTYINQ_QUOTESIZE (TTYINQ_DATASIZE / BMSIZE)
69 #define BMSIZE 32
70 #define GETBIT(tib,boff) \
71 ((tib)->tib_quotes[(boff) / BMSIZE] & (1 << ((boff) % BMSIZE)))
72 #define SETBIT(tib,boff) \
73 ((tib)->tib_quotes[(boff) / BMSIZE] |= (1 << ((boff) % BMSIZE)))
74 #define CLRBIT(tib,boff) \
75 ((tib)->tib_quotes[(boff) / BMSIZE] &= ~(1 << ((boff) % BMSIZE)))
76
77 struct ttyinq_block {
78 struct ttyinq_block *tib_prev;
79 struct ttyinq_block *tib_next;
80 uint32_t tib_quotes[TTYINQ_QUOTESIZE];
81 char tib_data[TTYINQ_DATASIZE];
82 };
83
84 static uma_zone_t ttyinq_zone;
85
86 #define TTYINQ_INSERT_TAIL(ti, tib) do { \
87 if (ti->ti_end == 0) { \
88 tib->tib_prev = NULL; \
89 tib->tib_next = ti->ti_firstblock; \
90 ti->ti_firstblock = tib; \
91 } else { \
92 tib->tib_prev = ti->ti_lastblock; \
93 tib->tib_next = ti->ti_lastblock->tib_next; \
94 ti->ti_lastblock->tib_next = tib; \
95 } \
96 if (tib->tib_next != NULL) \
97 tib->tib_next->tib_prev = tib; \
98 ti->ti_nblocks++; \
99 } while (0)
100
101 #define TTYINQ_REMOVE_HEAD(ti) do { \
102 ti->ti_firstblock = ti->ti_firstblock->tib_next; \
103 if (ti->ti_firstblock != NULL) \
104 ti->ti_firstblock->tib_prev = NULL; \
105 ti->ti_nblocks--; \
106 } while (0)
107
108 #define TTYINQ_RECYCLE(ti, tib) do { \
109 if (ti->ti_quota <= ti->ti_nblocks) \
110 uma_zfree(ttyinq_zone, tib); \
111 else \
112 TTYINQ_INSERT_TAIL(ti, tib); \
113 } while (0)
114
115 int
116 ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t size)
117 {
118 struct ttyinq_block *tib;
119
120 ti->ti_quota = howmany(size, TTYINQ_DATASIZE);
121
122 while (ti->ti_quota > ti->ti_nblocks) {
123 /*
124 * List is getting bigger.
125 * Add new blocks to the tail of the list.
126 *
127 * We must unlock the TTY temporarily, because we need
128 * to allocate memory. This won't be a problem, because
129 * in the worst case, another thread ends up here, which
130 * may cause us to allocate too many blocks, but this
131 * will be caught by the loop below.
132 */
133 tty_unlock(tp);
134 tib = uma_zalloc(ttyinq_zone, M_WAITOK);
135 tty_lock(tp);
136
137 if (tty_gone(tp)) {
138 uma_zfree(ttyinq_zone, tib);
139 return (ENXIO);
140 }
141
142 TTYINQ_INSERT_TAIL(ti, tib);
143 }
144 return (0);
145 }
146
147 void
148 ttyinq_free(struct ttyinq *ti)
149 {
150 struct ttyinq_block *tib;
151
152 ttyinq_flush(ti);
153 ti->ti_quota = 0;
154
155 while ((tib = ti->ti_firstblock) != NULL) {
156 TTYINQ_REMOVE_HEAD(ti);
157 uma_zfree(ttyinq_zone, tib);
158 }
159
160 MPASS(ti->ti_nblocks == 0);
161 }
162
163 int
164 ttyinq_read_uio(struct ttyinq *ti, struct tty *tp, struct uio *uio,
165 size_t rlen, size_t flen)
166 {
167
168 MPASS(rlen <= uio->uio_resid);
169
170 while (rlen > 0) {
171 int error;
172 struct ttyinq_block *tib;
173 size_t cbegin, cend, clen;
174
175 /* See if there still is data. */
176 if (ti->ti_begin == ti->ti_linestart)
177 return (0);
178 tib = ti->ti_firstblock;
179 if (tib == NULL)
180 return (0);
181
182 /*
183 * The end address should be the lowest of these three:
184 * - The write pointer
185 * - The blocksize - we can't read beyond the block
186 * - The end address if we could perform the full read
187 */
188 cbegin = ti->ti_begin;
189 cend = MIN(MIN(ti->ti_linestart, ti->ti_begin + rlen),
190 TTYINQ_DATASIZE);
191 clen = cend - cbegin;
192 MPASS(clen >= flen);
193 rlen -= clen;
194
195 /*
196 * We can prevent buffering in some cases:
197 * - We need to read the block until the end.
198 * - We don't need to read the block until the end, but
199 * there is no data beyond it, which allows us to move
200 * the write pointer to a new block.
201 */
202 if (cend == TTYINQ_DATASIZE || cend == ti->ti_end) {
203 /*
204 * Fast path: zero copy. Remove the first block,
205 * so we can unlock the TTY temporarily.
206 */
207 TTYINQ_REMOVE_HEAD(ti);
208 ti->ti_begin = 0;
209
210 /*
211 * Because we remove the first block, we must
212 * fix up the block offsets.
213 */
214 #define CORRECT_BLOCK(t) do { \
215 if (t <= TTYINQ_DATASIZE) \
216 t = 0; \
217 else \
218 t -= TTYINQ_DATASIZE; \
219 } while (0)
220 CORRECT_BLOCK(ti->ti_linestart);
221 CORRECT_BLOCK(ti->ti_reprint);
222 CORRECT_BLOCK(ti->ti_end);
223 #undef CORRECT_BLOCK
224
225 /*
226 * Temporary unlock and copy the data to
227 * userspace. We may need to flush trailing
228 * bytes, like EOF characters.
229 */
230 tty_unlock(tp);
231 error = uiomove(tib->tib_data + cbegin,
232 clen - flen, uio);
233 tty_lock(tp);
234
235 /* Block can now be readded to the list. */
236 TTYINQ_RECYCLE(ti, tib);
237 } else {
238 char ob[TTYINQ_DATASIZE - 1];
239
240 /*
241 * Slow path: store data in a temporary buffer.
242 */
243 memcpy(ob, tib->tib_data + cbegin, clen - flen);
244 ti->ti_begin += clen;
245 MPASS(ti->ti_begin < TTYINQ_DATASIZE);
246
247 /* Temporary unlock and copy the data to userspace. */
248 tty_unlock(tp);
249 error = uiomove(ob, clen - flen, uio);
250 tty_lock(tp);
251 }
252
253 if (error != 0)
254 return (error);
255 if (tty_gone(tp))
256 return (ENXIO);
257 }
258
259 return (0);
260 }
261
262 static __inline void
263 ttyinq_set_quotes(struct ttyinq_block *tib, size_t offset,
264 size_t length, int value)
265 {
266
267 if (value) {
268 /* Set the bits. */
269 for (; length > 0; length--, offset++)
270 SETBIT(tib, offset);
271 } else {
272 /* Unset the bits. */
273 for (; length > 0; length--, offset++)
274 CLRBIT(tib, offset);
275 }
276 }
277
278 size_t
279 ttyinq_write(struct ttyinq *ti, const void *buf, size_t nbytes, int quote)
280 {
281 const char *cbuf = buf;
282 struct ttyinq_block *tib;
283 unsigned int boff;
284 size_t l;
285
286 while (nbytes > 0) {
287 boff = ti->ti_end % TTYINQ_DATASIZE;
288
289 if (ti->ti_end == 0) {
290 /* First time we're being used or drained. */
291 MPASS(ti->ti_begin == 0);
292 tib = ti->ti_firstblock;
293 if (tib == NULL) {
294 /* Queue has no blocks. */
295 break;
296 }
297 ti->ti_lastblock = tib;
298 } else if (boff == 0) {
299 /* We reached the end of this block on last write. */
300 tib = ti->ti_lastblock->tib_next;
301 if (tib == NULL) {
302 /* We've reached the watermark. */
303 break;
304 }
305 ti->ti_lastblock = tib;
306 } else {
307 tib = ti->ti_lastblock;
308 }
309
310 /* Don't copy more than was requested. */
311 l = MIN(nbytes, TTYINQ_DATASIZE - boff);
312 MPASS(l > 0);
313 memcpy(tib->tib_data + boff, cbuf, l);
314
315 /* Set the quoting bits for the proper region. */
316 ttyinq_set_quotes(tib, boff, l, quote);
317
318 cbuf += l;
319 nbytes -= l;
320 ti->ti_end += l;
321 }
322
323 return (cbuf - (const char *)buf);
324 }
325
326 int
327 ttyinq_write_nofrag(struct ttyinq *ti, const void *buf, size_t nbytes, int quote)
328 {
329 size_t ret;
330
331 if (ttyinq_bytesleft(ti) < nbytes)
332 return (-1);
333
334 /* We should always be able to write it back. */
335 ret = ttyinq_write(ti, buf, nbytes, quote);
336 MPASS(ret == nbytes);
337
338 return (0);
339 }
340
341 void
342 ttyinq_canonicalize(struct ttyinq *ti)
343 {
344
345 ti->ti_linestart = ti->ti_reprint = ti->ti_end;
346 ti->ti_startblock = ti->ti_reprintblock = ti->ti_lastblock;
347 }
348
349 size_t
350 ttyinq_findchar(struct ttyinq *ti, const char *breakc, size_t maxlen,
351 char *lastc)
352 {
353 struct ttyinq_block *tib = ti->ti_firstblock;
354 unsigned int boff = ti->ti_begin;
355 unsigned int bend = MIN(MIN(TTYINQ_DATASIZE, ti->ti_linestart),
356 ti->ti_begin + maxlen);
357
358 MPASS(maxlen > 0);
359
360 if (tib == NULL)
361 return (0);
362
363 while (boff < bend) {
364 if (strchr(breakc, tib->tib_data[boff]) && !GETBIT(tib, boff)) {
365 *lastc = tib->tib_data[boff];
366 return (boff - ti->ti_begin + 1);
367 }
368 boff++;
369 }
370
371 /* Not found - just process the entire block. */
372 return (bend - ti->ti_begin);
373 }
374
375 void
376 ttyinq_flush(struct ttyinq *ti)
377 {
378 struct ttyinq_block *tib;
379
380 ti->ti_begin = 0;
381 ti->ti_linestart = 0;
382 ti->ti_reprint = 0;
383 ti->ti_end = 0;
384
385 /* Zero all data in the input queue to get rid of passwords. */
386 if (ttyinq_flush_secure) {
387 for (tib = ti->ti_firstblock; tib != NULL; tib = tib->tib_next)
388 bzero(&tib->tib_data, sizeof tib->tib_data);
389 }
390 }
391
392 int
393 ttyinq_peekchar(struct ttyinq *ti, char *c, int *quote)
394 {
395 unsigned int boff;
396 struct ttyinq_block *tib = ti->ti_lastblock;
397
398 if (ti->ti_linestart == ti->ti_end)
399 return (-1);
400
401 MPASS(ti->ti_end > 0);
402 boff = (ti->ti_end - 1) % TTYINQ_DATASIZE;
403
404 *c = tib->tib_data[boff];
405 *quote = GETBIT(tib, boff);
406
407 return (0);
408 }
409
410 void
411 ttyinq_unputchar(struct ttyinq *ti)
412 {
413
414 MPASS(ti->ti_linestart < ti->ti_end);
415
416 if (--ti->ti_end % TTYINQ_DATASIZE == 0) {
417 /* Roll back to the previous block. */
418 ti->ti_lastblock = ti->ti_lastblock->tib_prev;
419 /*
420 * This can only fail if we are unputchar()'ing the
421 * first character in the queue.
422 */
423 MPASS((ti->ti_lastblock == NULL) == (ti->ti_end == 0));
424 }
425 }
426
427 void
428 ttyinq_reprintpos_set(struct ttyinq *ti)
429 {
430
431 ti->ti_reprint = ti->ti_end;
432 ti->ti_reprintblock = ti->ti_lastblock;
433 }
434
435 void
436 ttyinq_reprintpos_reset(struct ttyinq *ti)
437 {
438
439 ti->ti_reprint = ti->ti_linestart;
440 ti->ti_reprintblock = ti->ti_startblock;
441 }
442
443 static void
444 ttyinq_line_iterate(struct ttyinq *ti,
445 ttyinq_line_iterator_t *iterator, void *data,
446 unsigned int offset, struct ttyinq_block *tib)
447 {
448 unsigned int boff;
449
450 /* Use the proper block when we're at the queue head. */
451 if (offset == 0)
452 tib = ti->ti_firstblock;
453
454 /* Iterate all characters and call the iterator function. */
455 for (; offset < ti->ti_end; offset++) {
456 boff = offset % TTYINQ_DATASIZE;
457 MPASS(tib != NULL);
458
459 /* Call back the iterator function. */
460 iterator(data, tib->tib_data[boff], GETBIT(tib, boff));
461
462 /* Last byte iterated - go to the next block. */
463 if (boff == TTYINQ_DATASIZE - 1)
464 tib = tib->tib_next;
465 MPASS(tib != NULL);
466 }
467 }
468
469 void
470 ttyinq_line_iterate_from_linestart(struct ttyinq *ti,
471 ttyinq_line_iterator_t *iterator, void *data)
472 {
473
474 ttyinq_line_iterate(ti, iterator, data,
475 ti->ti_linestart, ti->ti_startblock);
476 }
477
478 void
479 ttyinq_line_iterate_from_reprintpos(struct ttyinq *ti,
480 ttyinq_line_iterator_t *iterator, void *data)
481 {
482
483 ttyinq_line_iterate(ti, iterator, data,
484 ti->ti_reprint, ti->ti_reprintblock);
485 }
486
487 static void
488 ttyinq_startup(void *dummy)
489 {
490
491 ttyinq_zone = uma_zcreate("ttyinq", sizeof(struct ttyinq_block),
492 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
493 }
494
495 SYSINIT(ttyinq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyinq_startup, NULL);
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