1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2003 Ian Dowse. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD$
28 */
29
30 /*
31 * Generic message buffer support routines.
32 */
33
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/lock.h>
37 #include <sys/kernel.h>
38 #include <sys/mutex.h>
39 #include <sys/msgbuf.h>
40 #include <sys/sysctl.h>
41
42 /*
43 * Maximum number conversion buffer length: uintmax_t in base 2, plus <>
44 * around the priority, and a terminating NUL.
45 */
46 #define MAXPRIBUF (sizeof(intmax_t) * NBBY + 3)
47
48 /* Read/write sequence numbers are modulo a multiple of the buffer size. */
49 #define SEQMOD(size) ((size) * 16)
50
51 static u_int msgbuf_cksum(struct msgbuf *mbp);
52
53 /*
54 * Timestamps in msgbuf are useful when trying to diagnose when core dumps
55 * or other actions occurred.
56 */
57 static int msgbuf_show_timestamp = 0;
58 SYSCTL_INT(_kern, OID_AUTO, msgbuf_show_timestamp, CTLFLAG_RWTUN,
59 &msgbuf_show_timestamp, 0, "Show timestamp in msgbuf");
60
61 /*
62 * Initialize a message buffer of the specified size at the specified
63 * location. This also zeros the buffer area.
64 */
65 void
66 msgbuf_init(struct msgbuf *mbp, void *ptr, int size)
67 {
68
69 mbp->msg_ptr = ptr;
70 mbp->msg_size = size;
71 mbp->msg_seqmod = SEQMOD(size);
72 mbp->msg_lastpri = -1;
73 mbp->msg_flags = 0;
74 msgbuf_clear(mbp);
75 mbp->msg_magic = MSG_MAGIC;
76 bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
77 mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
78 }
79
80 /*
81 * Reinitialize a message buffer, retaining its previous contents if
82 * the size and checksum are correct. If the old contents cannot be
83 * recovered, the message buffer is cleared.
84 */
85 void
86 msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size)
87 {
88 u_int cksum;
89
90 if (mbp->msg_magic != MSG_MAGIC || mbp->msg_size != size) {
91 msgbuf_init(mbp, ptr, size);
92 return;
93 }
94 mbp->msg_seqmod = SEQMOD(size);
95 mbp->msg_wseq = MSGBUF_SEQNORM(mbp, mbp->msg_wseq);
96 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq);
97 mbp->msg_ptr = ptr;
98 cksum = msgbuf_cksum(mbp);
99 if (cksum != mbp->msg_cksum) {
100 if (bootverbose) {
101 printf("msgbuf cksum mismatch (read %x, calc %x)\n",
102 mbp->msg_cksum, cksum);
103 printf("Old msgbuf not recovered\n");
104 }
105 msgbuf_clear(mbp);
106 }
107
108 mbp->msg_lastpri = -1;
109 /* Assume that the old message buffer didn't end in a newline. */
110 mbp->msg_flags |= MSGBUF_NEEDNL;
111 bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
112 mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
113 }
114
115 /*
116 * Clear the message buffer.
117 */
118 void
119 msgbuf_clear(struct msgbuf *mbp)
120 {
121
122 bzero(mbp->msg_ptr, mbp->msg_size);
123 mbp->msg_wseq = 0;
124 mbp->msg_rseq = 0;
125 mbp->msg_cksum = 0;
126 mbp->msg_flags &= ~MSGBUF_WRAP;
127 }
128
129 /*
130 * Get a count of the number of unread characters in the message buffer.
131 */
132 int
133 msgbuf_getcount(struct msgbuf *mbp)
134 {
135 u_int len;
136
137 len = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_rseq);
138 if (len > mbp->msg_size)
139 len = mbp->msg_size;
140 return (len);
141 }
142
143 /*
144 * Add a character into the message buffer, and update the checksum and
145 * sequence number.
146 *
147 * The caller should hold the message buffer spinlock.
148 */
149 static void
150 msgbuf_do_addchar(struct msgbuf * const mbp, const int c)
151 {
152 u_int pos;
153
154 /* Make sure we properly wrap the sequence number. */
155 pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_wseq);
156 mbp->msg_cksum += (u_int)(u_char)c -
157 (u_int)(u_char)mbp->msg_ptr[pos];
158 mbp->msg_ptr[pos] = c;
159 mbp->msg_wseq = MSGBUF_SEQADD(mbp, mbp->msg_wseq, 1);
160 }
161
162 /*
163 * Append a character to a message buffer.
164 */
165 void
166 msgbuf_addchar(struct msgbuf *mbp, int c)
167 {
168 mtx_lock_spin(&mbp->msg_lock);
169
170 msgbuf_do_addchar(mbp, c);
171 if (mbp->msg_wseq >= mbp->msg_size)
172 mbp->msg_flags |= MSGBUF_WRAP;
173
174 mtx_unlock_spin(&mbp->msg_lock);
175 }
176
177 /*
178 * Append a NUL-terminated string with a priority to a message buffer.
179 * Filter carriage returns if the caller requests it.
180 *
181 * XXX The carriage return filtering behavior is present in the
182 * msglogchar() API, however testing has shown that we don't seem to send
183 * carriage returns down this path. So do we still need it?
184 */
185 void
186 msgbuf_addstr(struct msgbuf *mbp, int pri, const char *str, int filter_cr)
187 {
188 size_t len, prefix_len;
189 char prefix[MAXPRIBUF];
190 char buf[32];
191 int i, j, needtime;
192
193 len = strlen(str);
194 prefix_len = 0;
195
196 /* If we have a zero-length string, no need to do anything. */
197 if (len == 0)
198 return;
199
200 mtx_lock_spin(&mbp->msg_lock);
201
202 /*
203 * If this is true, we may need to insert a new priority sequence,
204 * so prepare the prefix.
205 */
206 if (pri != -1)
207 prefix_len = sprintf(prefix, "<%d>", pri);
208
209 /*
210 * Whenever there is a change in priority, we have to insert a
211 * newline, and a priority prefix if the priority is not -1. Here
212 * we detect whether there was a priority change, and whether we
213 * did not end with a newline. If that is the case, we need to
214 * insert a newline before this string.
215 */
216 if (mbp->msg_lastpri != pri && (mbp->msg_flags & MSGBUF_NEEDNL) != 0) {
217 msgbuf_do_addchar(mbp, '\n');
218 mbp->msg_flags &= ~MSGBUF_NEEDNL;
219 }
220
221 needtime = 1;
222 for (i = 0; i < len; i++) {
223 /*
224 * If we just had a newline, and the priority is not -1
225 * (and therefore prefix_len != 0), then we need a priority
226 * prefix for this line.
227 */
228 if ((mbp->msg_flags & MSGBUF_NEEDNL) == 0 && prefix_len != 0) {
229 int j;
230
231 for (j = 0; j < prefix_len; j++)
232 msgbuf_do_addchar(mbp, prefix[j]);
233 }
234
235 if (msgbuf_show_timestamp && needtime == 1 &&
236 (mbp->msg_flags & MSGBUF_NEEDNL) == 0) {
237 if (msgbuf_show_timestamp == 1) {
238 snprintf(buf, sizeof(buf), "[%jd] ",
239 (intmax_t)time_uptime);
240 } else {
241 struct timeval tv;
242
243 microuptime(&tv);
244 snprintf(buf, sizeof(buf), "[%jd.%06d] ",
245 (intmax_t)tv.tv_sec, (int)tv.tv_usec);
246 }
247 for (j = 0; buf[j] != '\0'; j++)
248 msgbuf_do_addchar(mbp, buf[j]);
249 needtime = 0;
250 }
251
252 /*
253 * Don't copy carriage returns if the caller requested
254 * filtering.
255 *
256 * XXX This matches the behavior of msglogchar(), but is it
257 * necessary? Testing has shown that we don't seem to get
258 * carriage returns here.
259 */
260 if ((filter_cr != 0) && (str[i] == '\r'))
261 continue;
262
263 /*
264 * Clear this flag if we see a newline. This affects whether
265 * we need to insert a new prefix or insert a newline later.
266 */
267 if (str[i] == '\n')
268 mbp->msg_flags &= ~MSGBUF_NEEDNL;
269 else
270 mbp->msg_flags |= MSGBUF_NEEDNL;
271
272 msgbuf_do_addchar(mbp, str[i]);
273 }
274 if (mbp->msg_wseq >= mbp->msg_size)
275 mbp->msg_flags |= MSGBUF_WRAP;
276
277 /*
278 * Set the last priority.
279 */
280 mbp->msg_lastpri = pri;
281
282 mtx_unlock_spin(&mbp->msg_lock);
283
284 }
285
286 /*
287 * Read and mark as read a character from a message buffer.
288 * Returns the character, or -1 if no characters are available.
289 */
290 int
291 msgbuf_getchar(struct msgbuf *mbp)
292 {
293 u_int len, wseq;
294 int c;
295
296 mtx_lock_spin(&mbp->msg_lock);
297
298 wseq = mbp->msg_wseq;
299 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
300 if (len == 0) {
301 mtx_unlock_spin(&mbp->msg_lock);
302 return (-1);
303 }
304 if (len > mbp->msg_size)
305 mbp->msg_rseq = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size);
306 c = (u_char)mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq)];
307 mbp->msg_rseq = MSGBUF_SEQADD(mbp, mbp->msg_rseq, 1);
308
309 mtx_unlock_spin(&mbp->msg_lock);
310
311 return (c);
312 }
313
314 /*
315 * Read and mark as read a number of characters from a message buffer.
316 * Returns the number of characters that were placed in `buf'.
317 */
318 int
319 msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen)
320 {
321 u_int len, pos, wseq;
322
323 mtx_lock_spin(&mbp->msg_lock);
324
325 wseq = mbp->msg_wseq;
326 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
327 if (len == 0) {
328 mtx_unlock_spin(&mbp->msg_lock);
329 return (0);
330 }
331 if (len > mbp->msg_size) {
332 mbp->msg_rseq = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size);
333 len = mbp->msg_size;
334 }
335 pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq);
336 len = min(len, mbp->msg_size - pos);
337 len = min(len, (u_int)buflen);
338
339 bcopy(&mbp->msg_ptr[pos], buf, len);
340 mbp->msg_rseq = MSGBUF_SEQADD(mbp, mbp->msg_rseq, len);
341
342 mtx_unlock_spin(&mbp->msg_lock);
343
344 return (len);
345 }
346
347 /*
348 * Peek at the full contents of a message buffer without marking any
349 * data as read. `seqp' should point to an unsigned integer that
350 * msgbuf_peekbytes() can use to retain state between calls so that
351 * the whole message buffer can be read in multiple short reads.
352 * To initialise this variable to the start of the message buffer,
353 * call msgbuf_peekbytes() with a NULL `buf' parameter.
354 *
355 * Returns the number of characters that were placed in `buf'.
356 */
357 int
358 msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen, u_int *seqp)
359 {
360 u_int len, pos, wseq;
361
362 mtx_lock_spin(&mbp->msg_lock);
363
364 if (buf == NULL) {
365 /* Just initialise *seqp. */
366 if (mbp->msg_flags & MSGBUF_WRAP)
367 *seqp = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_size);
368 else
369 *seqp = 0;
370 mtx_unlock_spin(&mbp->msg_lock);
371 return (0);
372 }
373
374 wseq = mbp->msg_wseq;
375 len = MSGBUF_SEQSUB(mbp, wseq, *seqp);
376 if (len == 0) {
377 mtx_unlock_spin(&mbp->msg_lock);
378 return (0);
379 }
380 if (len > mbp->msg_size) {
381 *seqp = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size);
382 len = mbp->msg_size;
383 }
384 pos = MSGBUF_SEQ_TO_POS(mbp, *seqp);
385 len = min(len, mbp->msg_size - pos);
386 len = min(len, (u_int)buflen);
387 bcopy(&mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, *seqp)], buf, len);
388 *seqp = MSGBUF_SEQADD(mbp, *seqp, len);
389
390 mtx_unlock_spin(&mbp->msg_lock);
391
392 return (len);
393 }
394
395 /*
396 * Compute the checksum for the complete message buffer contents.
397 */
398 static u_int
399 msgbuf_cksum(struct msgbuf *mbp)
400 {
401 u_int i, sum;
402
403 sum = 0;
404 for (i = 0; i < mbp->msg_size; i++)
405 sum += (u_char)mbp->msg_ptr[i];
406 return (sum);
407 }
408
409 /*
410 * Copy from one message buffer to another.
411 */
412 void
413 msgbuf_copy(struct msgbuf *src, struct msgbuf *dst)
414 {
415 int c;
416
417 while ((c = msgbuf_getchar(src)) >= 0)
418 msgbuf_addchar(dst, c);
419 }
420
421 /*
422 * Get a snapshot of the message buffer, without modifying its internal state
423 * (i.e. don't mark any new characters as read).
424 */
425 void
426 msgbuf_duplicate(struct msgbuf *src, struct msgbuf *dst, char *dst_msgptr)
427 {
428
429 mtx_lock_spin(&src->msg_lock);
430 bcopy(src, dst, sizeof(struct msgbuf));
431 dst->msg_ptr = dst_msgptr;
432 bcopy(src->msg_ptr, dst->msg_ptr, src->msg_size);
433 mtx_unlock_spin(&src->msg_lock);
434 }
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