2 * Copyright (c) 2003 Ian Dowse. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * Generic message buffer support routines.
32 #include <sys/param.h>
33 #include <sys/systm.h>
35 #include <sys/kernel.h>
36 #include <sys/mutex.h>
37 #include <sys/msgbuf.h>
38 #include <sys/sysctl.h>
41 * Maximum number conversion buffer length: uintmax_t in base 2, plus <>
42 * around the priority, and a terminating NUL.
44 #define MAXPRIBUF (sizeof(intmax_t) * NBBY + 3)
46 /* Read/write sequence numbers are modulo a multiple of the buffer size. */
47 #define SEQMOD(size) ((size) * 16)
49 static u_int msgbuf_cksum(struct msgbuf *mbp);
52 * Timestamps in msgbuf are useful when trying to diagnose when core dumps
53 * or other actions occured.
55 static int msgbuf_show_timestamp = 0;
56 SYSCTL_INT(_kern, OID_AUTO, msgbuf_show_timestamp, CTLFLAG_RWTUN,
57 &msgbuf_show_timestamp, 0, "Show timestamp in msgbuf");
60 * Initialize a message buffer of the specified size at the specified
61 * location. This also zeros the buffer area.
64 msgbuf_init(struct msgbuf *mbp, void *ptr, int size)
69 mbp->msg_seqmod = SEQMOD(size);
71 mbp->msg_magic = MSG_MAGIC;
72 mbp->msg_lastpri = -1;
74 bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
75 mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
79 * Reinitialize a message buffer, retaining its previous contents if
80 * the size and checksum are correct. If the old contents cannot be
81 * recovered, the message buffer is cleared.
84 msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size)
88 if (mbp->msg_magic != MSG_MAGIC || mbp->msg_size != size) {
89 msgbuf_init(mbp, ptr, size);
92 mbp->msg_seqmod = SEQMOD(size);
93 mbp->msg_wseq = MSGBUF_SEQNORM(mbp, mbp->msg_wseq);
94 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq);
96 cksum = msgbuf_cksum(mbp);
97 if (cksum != mbp->msg_cksum) {
99 printf("msgbuf cksum mismatch (read %x, calc %x)\n",
100 mbp->msg_cksum, cksum);
101 printf("Old msgbuf not recovered\n");
106 mbp->msg_lastpri = -1;
107 /* Assume that the old message buffer didn't end in a newline. */
108 mbp->msg_flags |= MSGBUF_NEEDNL;
109 bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
110 mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
114 * Clear the message buffer.
117 msgbuf_clear(struct msgbuf *mbp)
120 bzero(mbp->msg_ptr, mbp->msg_size);
127 * Get a count of the number of unread characters in the message buffer.
130 msgbuf_getcount(struct msgbuf *mbp)
134 len = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_rseq);
135 if (len > mbp->msg_size)
141 * Add a character into the message buffer, and update the checksum and
144 * The caller should hold the message buffer spinlock.
148 msgbuf_do_addchar(struct msgbuf * const mbp, u_int * const seq, const int c)
152 /* Make sure we properly wrap the sequence number. */
153 pos = MSGBUF_SEQ_TO_POS(mbp, *seq);
154 mbp->msg_cksum += (u_int)(u_char)c -
155 (u_int)(u_char)mbp->msg_ptr[pos];
156 mbp->msg_ptr[pos] = c;
157 *seq = MSGBUF_SEQNORM(mbp, *seq + 1);
161 * Append a character to a message buffer.
164 msgbuf_addchar(struct msgbuf *mbp, int c)
166 mtx_lock_spin(&mbp->msg_lock);
168 msgbuf_do_addchar(mbp, &mbp->msg_wseq, c);
170 mtx_unlock_spin(&mbp->msg_lock);
174 * Append a NUL-terminated string with a priority to a message buffer.
175 * Filter carriage returns if the caller requests it.
177 * XXX The carriage return filtering behavior is present in the
178 * msglogchar() API, however testing has shown that we don't seem to send
179 * carriage returns down this path. So do we still need it?
182 msgbuf_addstr(struct msgbuf *mbp, int pri, char *str, int filter_cr)
185 size_t len, prefix_len;
186 char prefix[MAXPRIBUF];
188 int nl, i, j, needtime;
194 /* If we have a zero-length string, no need to do anything. */
198 mtx_lock_spin(&mbp->msg_lock);
201 * If this is true, we may need to insert a new priority sequence,
202 * so prepare the prefix.
205 prefix_len = sprintf(prefix, "<%d>", pri);
208 * Starting write sequence number.
213 * Whenever there is a change in priority, we have to insert a
214 * newline, and a priority prefix if the priority is not -1. Here
215 * we detect whether there was a priority change, and whether we
216 * did not end with a newline. If that is the case, we need to
217 * insert a newline before this string.
219 if (mbp->msg_lastpri != pri && (mbp->msg_flags & MSGBUF_NEEDNL) != 0) {
221 msgbuf_do_addchar(mbp, &seq, '\n');
222 mbp->msg_flags &= ~MSGBUF_NEEDNL;
226 for (i = 0; i < len; i++) {
228 * If we just had a newline, and the priority is not -1
229 * (and therefore prefix_len != 0), then we need a priority
230 * prefix for this line.
232 if ((mbp->msg_flags & MSGBUF_NEEDNL) == 0 && prefix_len != 0) {
235 for (j = 0; j < prefix_len; j++)
236 msgbuf_do_addchar(mbp, &seq, prefix[j]);
239 if (msgbuf_show_timestamp && needtime == 1 &&
240 (mbp->msg_flags & MSGBUF_NEEDNL) == 0) {
242 snprintf(buf, sizeof(buf), "[%jd] ",
243 (intmax_t)time_uptime);
244 for (j = 0; buf[j] != '\0'; j++)
245 msgbuf_do_addchar(mbp, &seq, buf[j]);
250 * Don't copy carriage returns if the caller requested
253 * XXX This matches the behavior of msglogchar(), but is it
254 * necessary? Testing has shown that we don't seem to get
255 * carriage returns here.
257 if ((filter_cr != 0) && (str[i] == '\r'))
261 * Clear this flag if we see a newline. This affects whether
262 * we need to insert a new prefix or insert a newline later.
265 mbp->msg_flags &= ~MSGBUF_NEEDNL;
267 mbp->msg_flags |= MSGBUF_NEEDNL;
269 msgbuf_do_addchar(mbp, &seq, str[i]);
272 * Update the write sequence number for the actual number of
273 * characters we put in the message buffer. (Depends on whether
274 * carriage returns are filtered.)
279 * Set the last priority.
281 mbp->msg_lastpri = pri;
283 mtx_unlock_spin(&mbp->msg_lock);
288 * Read and mark as read a character from a message buffer.
289 * Returns the character, or -1 if no characters are available.
292 msgbuf_getchar(struct msgbuf *mbp)
297 mtx_lock_spin(&mbp->msg_lock);
299 wseq = mbp->msg_wseq;
300 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
302 mtx_unlock_spin(&mbp->msg_lock);
305 if (len > mbp->msg_size)
306 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
307 c = (u_char)mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq)];
308 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + 1);
310 mtx_unlock_spin(&mbp->msg_lock);
316 * Read and mark as read a number of characters from a message buffer.
317 * Returns the number of characters that were placed in `buf'.
320 msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen)
322 u_int len, pos, wseq;
324 mtx_lock_spin(&mbp->msg_lock);
326 wseq = mbp->msg_wseq;
327 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
329 mtx_unlock_spin(&mbp->msg_lock);
332 if (len > mbp->msg_size) {
333 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
336 pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq);
337 len = min(len, mbp->msg_size - pos);
338 len = min(len, (u_int)buflen);
340 bcopy(&mbp->msg_ptr[pos], buf, len);
341 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + len);
343 mtx_unlock_spin(&mbp->msg_lock);
349 * Peek at the full contents of a message buffer without marking any
350 * data as read. `seqp' should point to an unsigned integer that
351 * msgbuf_peekbytes() can use to retain state between calls so that
352 * the whole message buffer can be read in multiple short reads.
353 * To initialise this variable to the start of the message buffer,
354 * call msgbuf_peekbytes() with a NULL `buf' parameter.
356 * Returns the number of characters that were placed in `buf'.
359 msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen, u_int *seqp)
361 u_int len, pos, wseq;
363 mtx_lock_spin(&mbp->msg_lock);
366 /* Just initialise *seqp. */
367 *seqp = MSGBUF_SEQNORM(mbp, mbp->msg_wseq - mbp->msg_size);
368 mtx_unlock_spin(&mbp->msg_lock);
372 wseq = mbp->msg_wseq;
373 len = MSGBUF_SEQSUB(mbp, wseq, *seqp);
375 mtx_unlock_spin(&mbp->msg_lock);
378 if (len > mbp->msg_size) {
379 *seqp = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
382 pos = MSGBUF_SEQ_TO_POS(mbp, *seqp);
383 len = min(len, mbp->msg_size - pos);
384 len = min(len, (u_int)buflen);
385 bcopy(&mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, *seqp)], buf, len);
386 *seqp = MSGBUF_SEQNORM(mbp, *seqp + len);
388 mtx_unlock_spin(&mbp->msg_lock);
394 * Compute the checksum for the complete message buffer contents.
397 msgbuf_cksum(struct msgbuf *mbp)
402 for (i = 0; i < mbp->msg_size; i++)
403 sum += (u_char)mbp->msg_ptr[i];
408 * Copy from one message buffer to another.
411 msgbuf_copy(struct msgbuf *src, struct msgbuf *dst)
415 while ((c = msgbuf_getchar(src)) >= 0)
416 msgbuf_addchar(dst, c);