1 /*
2 * Copyright (c) 2006-2023, RT-Thread Development Team
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 *
6 * Change Logs:
7 * Date Author Notes
8 * 2023-11-13 Shell init ver.
9 */
10
11 #include "../bsd_porting.h"
12 #include "../terminal.h"
13
14 /*-
15 * SPDX-License-Identifier: BSD-2-Clause
16 *
17 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
18 * All rights reserved.
19 *
20 * Portions of this software were developed under sponsorship from Snow
21 * B.V., the Netherlands.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the above copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 *
32 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
42 * SUCH DAMAGE.
43 */
44
45 /*
46 * TTY output queue buffering.
47 *
48 * The previous design of the TTY layer offered the so-called clists.
49 * These clists were used for both the input queues and the output
50 * queue. We don't use certain features on the output side, like quoting
51 * bits for parity marking and such. This mechanism is similar to the
52 * old clists, but only contains the features we need to buffer the
53 * output.
54 */
55
56 struct ttyoutq_block
57 {
58 struct ttyoutq_block *tob_next;
59 char tob_data[TTYOUTQ_DATASIZE];
60 };
61
62 static uma_zone_t ttyoutq_zone;
63
64 #define TTYOUTQ_INSERT_TAIL(to, tob) \
65 do \
66 { \
67 if (to->to_end == 0) \
68 { \
69 tob->tob_next = to->to_firstblock; \
70 to->to_firstblock = tob; \
71 } \
72 else \
73 { \
74 tob->tob_next = to->to_lastblock->tob_next; \
75 to->to_lastblock->tob_next = tob; \
76 } \
77 to->to_nblocks++; \
78 } while (0)
79
80 #define TTYOUTQ_REMOVE_HEAD(to) \
81 do \
82 { \
83 to->to_firstblock = to->to_firstblock->tob_next; \
84 to->to_nblocks--; \
85 } while (0)
86
87 #define TTYOUTQ_RECYCLE(to, tob) \
88 do \
89 { \
90 if (to->to_quota <= to->to_nblocks) \
91 uma_zfree(ttyoutq_zone, tob); \
92 else \
93 TTYOUTQ_INSERT_TAIL(to, tob); \
94 } while (0)
95
ttyoutq_flush(struct ttyoutq * to)96 void ttyoutq_flush(struct ttyoutq *to)
97 {
98 to->to_begin = 0;
99 to->to_end = 0;
100 }
101
ttyoutq_setsize(struct ttyoutq * to,struct lwp_tty * tp,size_t size)102 int ttyoutq_setsize(struct ttyoutq *to, struct lwp_tty *tp, size_t size)
103 {
104 struct ttyoutq_block *tob;
105
106 to->to_quota = howmany(size, TTYOUTQ_DATASIZE);
107
108 while (to->to_quota > to->to_nblocks)
109 {
110 /*
111 * List is getting bigger.
112 * Add new blocks to the tail of the list.
113 *
114 * We must unlock the TTY temporarily, because we need
115 * to allocate memory. This won't be a problem, because
116 * in the worst case, another thread ends up here, which
117 * may cause us to allocate too many blocks, but this
118 * will be caught by the loop below.
119 */
120 tty_unlock(tp);
121 tob = uma_zalloc(ttyoutq_zone, M_WAITOK);
122 tty_lock(tp);
123
124 if (tty_gone(tp))
125 {
126 uma_zfree(ttyoutq_zone, tob);
127 return -ENXIO;
128 }
129
130 TTYOUTQ_INSERT_TAIL(to, tob);
131 }
132 return 0;
133 }
134
ttyoutq_free(struct ttyoutq * to)135 void ttyoutq_free(struct ttyoutq *to)
136 {
137 struct ttyoutq_block *tob;
138
139 ttyoutq_flush(to);
140 to->to_quota = 0;
141
142 while ((tob = to->to_firstblock) != NULL)
143 {
144 TTYOUTQ_REMOVE_HEAD(to);
145 uma_zfree(ttyoutq_zone, tob);
146 }
147
148 MPASS(to->to_nblocks == 0);
149 }
150
ttyoutq_read(struct ttyoutq * to,void * buf,size_t len)151 size_t ttyoutq_read(struct ttyoutq *to, void *buf, size_t len)
152 {
153 char *cbuf = buf;
154
155 while (len > 0)
156 {
157 struct ttyoutq_block *tob;
158 size_t cbegin, cend, clen;
159
160 /* See if there still is data. */
161 if (to->to_begin == to->to_end)
162 break;
163 tob = to->to_firstblock;
164 if (tob == NULL)
165 break;
166
167 /*
168 * The end address should be the lowest of these three:
169 * - The write pointer
170 * - The blocksize - we can't read beyond the block
171 * - The end address if we could perform the full read
172 */
173 cbegin = to->to_begin;
174 cend = MIN(MIN(to->to_end, to->to_begin + len), TTYOUTQ_DATASIZE);
175 clen = cend - cbegin;
176
177 /* Copy the data out of the buffers. */
178 memcpy(cbuf, tob->tob_data + cbegin, clen);
179 cbuf += clen;
180 len -= clen;
181
182 if (cend == to->to_end)
183 {
184 /* Read the complete queue. */
185 to->to_begin = 0;
186 to->to_end = 0;
187 }
188 else if (cend == TTYOUTQ_DATASIZE)
189 {
190 /* Read the block until the end. */
191 TTYOUTQ_REMOVE_HEAD(to);
192 to->to_begin = 0;
193 to->to_end -= TTYOUTQ_DATASIZE;
194 TTYOUTQ_RECYCLE(to, tob);
195 }
196 else
197 {
198 /* Read the block partially. */
199 to->to_begin += clen;
200 }
201 }
202
203 return cbuf - (char *)buf;
204 }
205
206 /*
207 * An optimized version of ttyoutq_read() which can be used in pseudo
208 * TTY drivers to directly copy data from the outq to userspace, instead
209 * of buffering it.
210 *
211 * We can only copy data directly if we need to read the entire block
212 * back to the user, because we temporarily remove the block from the
213 * queue. Otherwise we need to copy it to a temporary buffer first, to
214 * make sure data remains in the correct order.
215 */
ttyoutq_read_uio(struct ttyoutq * to,struct lwp_tty * tp,struct uio * uio)216 int ttyoutq_read_uio(struct ttyoutq *to, struct lwp_tty *tp, struct uio *uio)
217 {
218 while (uio->uio_resid > 0)
219 {
220 int error;
221 struct ttyoutq_block *tob;
222 size_t cbegin, cend, clen;
223
224 /* See if there still is data. */
225 if (to->to_begin == to->to_end)
226 return 0;
227 tob = to->to_firstblock;
228 if (tob == NULL)
229 return 0;
230
231 /*
232 * The end address should be the lowest of these three:
233 * - The write pointer
234 * - The blocksize - we can't read beyond the block
235 * - The end address if we could perform the full read
236 */
237 cbegin = to->to_begin;
238 cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid),
239 TTYOUTQ_DATASIZE);
240 clen = cend - cbegin;
241
242 /*
243 * We can prevent buffering in some cases:
244 * - We need to read the block until the end.
245 * - We don't need to read the block until the end, but
246 * there is no data beyond it, which allows us to move
247 * the write pointer to a new block.
248 */
249 if (cend == TTYOUTQ_DATASIZE || cend == to->to_end)
250 {
251 /*
252 * Fast path: zero copy. Remove the first block,
253 * so we can unlock the TTY temporarily.
254 */
255 TTYOUTQ_REMOVE_HEAD(to);
256 to->to_begin = 0;
257 if (to->to_end <= TTYOUTQ_DATASIZE)
258 to->to_end = 0;
259 else
260 to->to_end -= TTYOUTQ_DATASIZE;
261
262 /* Temporary unlock and copy the data to userspace. */
263 tty_unlock(tp);
264 error = uiomove(tob->tob_data + cbegin, clen, uio);
265 tty_lock(tp);
266
267 /* Block can now be readded to the list. */
268 TTYOUTQ_RECYCLE(to, tob);
269 }
270 else
271 {
272 char ob[TTYOUTQ_DATASIZE - 1];
273
274 /*
275 * Slow path: store data in a temporary buffer.
276 */
277 memcpy(ob, tob->tob_data + cbegin, clen);
278 to->to_begin += clen;
279 MPASS(to->to_begin < TTYOUTQ_DATASIZE);
280
281 /* Temporary unlock and copy the data to userspace. */
282 tty_unlock(tp);
283 error = uiomove(ob, clen, uio);
284 tty_lock(tp);
285 }
286
287 if (error != 0)
288 return error;
289 }
290
291 return 0;
292 }
293
ttyoutq_write(struct ttyoutq * to,const void * buf,size_t nbytes)294 size_t ttyoutq_write(struct ttyoutq *to, const void *buf, size_t nbytes)
295 {
296 const char *cbuf = buf;
297 struct ttyoutq_block *tob;
298 unsigned int boff;
299 size_t l;
300
301 while (nbytes > 0)
302 {
303 boff = to->to_end % TTYOUTQ_DATASIZE;
304
305 if (to->to_end == 0)
306 {
307 /* First time we're being used or drained. */
308 MPASS(to->to_begin == 0);
309 tob = to->to_firstblock;
310 if (tob == NULL)
311 {
312 /* Queue has no blocks. */
313 break;
314 }
315 to->to_lastblock = tob;
316 }
317 else if (boff == 0)
318 {
319 /* We reached the end of this block on last write. */
320 tob = to->to_lastblock->tob_next;
321 if (tob == NULL)
322 {
323 /* We've reached the watermark. */
324 break;
325 }
326 to->to_lastblock = tob;
327 }
328 else
329 {
330 tob = to->to_lastblock;
331 }
332
333 /* Don't copy more than was requested. */
334 l = MIN(nbytes, TTYOUTQ_DATASIZE - boff);
335 MPASS(l > 0);
336 memcpy(tob->tob_data + boff, cbuf, l);
337
338 cbuf += l;
339 nbytes -= l;
340 to->to_end += l;
341 }
342
343 return (cbuf - (const char *)buf);
344 }
345
ttyoutq_write_nofrag(struct ttyoutq * to,const void * buf,size_t nbytes)346 int ttyoutq_write_nofrag(struct ttyoutq *to, const void *buf, size_t nbytes)
347 {
348 size_t ret __unused;
349
350 if (ttyoutq_bytesleft(to) < nbytes)
351 return -1;
352
353 /* We should always be able to write it back. */
354 ret = ttyoutq_write(to, buf, nbytes);
355 MPASS(ret == nbytes);
356
357 return 0;
358 }
359
ttyoutq_startup(void)360 static int ttyoutq_startup(void)
361 {
362 ttyoutq_zone = uma_zcreate("ttyoutq", sizeof(struct ttyoutq_block), NULL,
363 NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
364 return 0;
365 }
366 INIT_PREV_EXPORT(ttyoutq_startup);
367
368 #if 0
369 SYSINIT(ttyoutq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyoutq_startup, NULL);
370 #endif
371