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/mutex.h>
36 #include <sys/msgbuf.h>
39 * Maximum number conversion buffer length: uintmax_t in base 2, plus <>
40 * around the priority, and a terminating NUL.
42 #define MAXPRIBUF (sizeof(intmax_t) * NBBY + 3)
44 /* Read/write sequence numbers are modulo a multiple of the buffer size. */
45 #define SEQMOD(size) ((size) * 16)
47 static u_int msgbuf_cksum(struct msgbuf *mbp);
50 * Initialize a message buffer of the specified size at the specified
51 * location. This also zeros the buffer area.
54 msgbuf_init(struct msgbuf *mbp, void *ptr, int size)
59 mbp->msg_seqmod = SEQMOD(size);
61 mbp->msg_magic = MSG_MAGIC;
62 mbp->msg_lastpri = -1;
64 bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
65 mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
69 * Reinitialize a message buffer, retaining its previous contents if
70 * the size and checksum are correct. If the old contents cannot be
71 * recovered, the message buffer is cleared.
74 msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size)
78 if (mbp->msg_magic != MSG_MAGIC || mbp->msg_size != size) {
79 msgbuf_init(mbp, ptr, size);
82 mbp->msg_seqmod = SEQMOD(size);
83 mbp->msg_wseq = MSGBUF_SEQNORM(mbp, mbp->msg_wseq);
84 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq);
86 cksum = msgbuf_cksum(mbp);
87 if (cksum != mbp->msg_cksum) {
89 printf("msgbuf cksum mismatch (read %x, calc %x)\n",
90 mbp->msg_cksum, cksum);
91 printf("Old msgbuf not recovered\n");
96 mbp->msg_lastpri = -1;
97 /* Assume that the old message buffer didn't end in a newline. */
99 bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
100 mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
104 * Clear the message buffer.
107 msgbuf_clear(struct msgbuf *mbp)
110 bzero(mbp->msg_ptr, mbp->msg_size);
117 * Get a count of the number of unread characters in the message buffer.
120 msgbuf_getcount(struct msgbuf *mbp)
124 len = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_rseq);
125 if (len > mbp->msg_size)
131 * Add a character into the message buffer, and update the checksum and
134 * The caller should hold the message buffer spinlock.
137 msgbuf_do_addchar(struct msgbuf *mbp, u_int *seq, int c)
141 /* Make sure we properly wrap the sequence number. */
142 pos = MSGBUF_SEQ_TO_POS(mbp, *seq);
144 mbp->msg_cksum += (u_int)c -
145 (u_int)(u_char)mbp->msg_ptr[pos];
147 mbp->msg_ptr[pos] = c;
149 *seq = MSGBUF_SEQNORM(mbp, *seq + 1);
153 * Append a character to a message buffer.
156 msgbuf_addchar(struct msgbuf *mbp, int c)
158 mtx_lock_spin(&mbp->msg_lock);
160 msgbuf_do_addchar(mbp, &mbp->msg_wseq, c);
162 mtx_unlock_spin(&mbp->msg_lock);
166 * Append a NUL-terminated string with a priority to a message buffer.
167 * Filter carriage returns if the caller requests it.
169 * XXX The carriage return filtering behavior is present in the
170 * msglogchar() API, however testing has shown that we don't seem to send
171 * carriage returns down this path. So do we still need it?
174 msgbuf_addstr(struct msgbuf *mbp, int pri, char *str, int filter_cr)
177 size_t len, prefix_len;
178 char prefix[MAXPRIBUF];
185 /* If we have a zero-length string, no need to do anything. */
189 mtx_lock_spin(&mbp->msg_lock);
192 * If this is true, we may need to insert a new priority sequence,
193 * so prepare the prefix.
196 prefix_len = sprintf(prefix, "<%d>", pri);
199 * Starting write sequence number.
204 * Whenever there is a change in priority, we have to insert a
205 * newline, and a priority prefix if the priority is not -1. Here
206 * we detect whether there was a priority change, and whether we
207 * did not end with a newline. If that is the case, we need to
208 * insert a newline before this string.
210 if (mbp->msg_lastpri != pri && mbp->msg_needsnl != 0) {
212 msgbuf_do_addchar(mbp, &seq, '\n');
213 mbp->msg_needsnl = 0;
216 for (i = 0; i < len; i++) {
218 * If we just had a newline, and the priority is not -1
219 * (and therefore prefix_len != 0), then we need a priority
220 * prefix for this line.
222 if (mbp->msg_needsnl == 0 && prefix_len != 0) {
225 for (j = 0; j < prefix_len; j++)
226 msgbuf_do_addchar(mbp, &seq, prefix[j]);
230 * Don't copy carriage returns if the caller requested
233 * XXX This matches the behavior of msglogchar(), but is it
234 * necessary? Testing has shown that we don't seem to get
235 * carriage returns here.
237 if ((filter_cr != 0) && (str[i] == '\r'))
241 * Clear this flag if we see a newline. This affects whether
242 * we need to insert a new prefix or insert a newline later.
245 mbp->msg_needsnl = 0;
247 mbp->msg_needsnl = 1;
249 msgbuf_do_addchar(mbp, &seq, str[i]);
252 * Update the write sequence number for the actual number of
253 * characters we put in the message buffer. (Depends on whether
254 * carriage returns are filtered.)
259 * Set the last priority.
261 mbp->msg_lastpri = pri;
263 mtx_unlock_spin(&mbp->msg_lock);
268 * Read and mark as read a character from a message buffer.
269 * Returns the character, or -1 if no characters are available.
272 msgbuf_getchar(struct msgbuf *mbp)
277 mtx_lock_spin(&mbp->msg_lock);
279 wseq = mbp->msg_wseq;
280 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
282 mtx_unlock_spin(&mbp->msg_lock);
285 if (len > mbp->msg_size)
286 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
287 c = (u_char)mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq)];
288 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + 1);
290 mtx_unlock_spin(&mbp->msg_lock);
296 * Read and mark as read a number of characters from a message buffer.
297 * Returns the number of characters that were placed in `buf'.
300 msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen)
302 u_int len, pos, wseq;
304 mtx_lock_spin(&mbp->msg_lock);
306 wseq = mbp->msg_wseq;
307 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
309 mtx_unlock_spin(&mbp->msg_lock);
312 if (len > mbp->msg_size) {
313 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
316 pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq);
317 len = min(len, mbp->msg_size - pos);
318 len = min(len, (u_int)buflen);
320 bcopy(&mbp->msg_ptr[pos], buf, len);
321 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + len);
323 mtx_unlock_spin(&mbp->msg_lock);
329 * Peek at the full contents of a message buffer without marking any
330 * data as read. `seqp' should point to an unsigned integer that
331 * msgbuf_peekbytes() can use to retain state between calls so that
332 * the whole message buffer can be read in multiple short reads.
333 * To initialise this variable to the start of the message buffer,
334 * call msgbuf_peekbytes() with a NULL `buf' parameter.
336 * Returns the number of characters that were placed in `buf'.
339 msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen, u_int *seqp)
341 u_int len, pos, wseq;
343 mtx_lock_spin(&mbp->msg_lock);
346 /* Just initialise *seqp. */
347 *seqp = MSGBUF_SEQNORM(mbp, mbp->msg_wseq - mbp->msg_size);
348 mtx_unlock_spin(&mbp->msg_lock);
352 wseq = mbp->msg_wseq;
353 len = MSGBUF_SEQSUB(mbp, wseq, *seqp);
355 mtx_unlock_spin(&mbp->msg_lock);
358 if (len > mbp->msg_size) {
359 *seqp = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
362 pos = MSGBUF_SEQ_TO_POS(mbp, *seqp);
363 len = min(len, mbp->msg_size - pos);
364 len = min(len, (u_int)buflen);
365 bcopy(&mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, *seqp)], buf, len);
366 *seqp = MSGBUF_SEQNORM(mbp, *seqp + len);
368 mtx_unlock_spin(&mbp->msg_lock);
374 * Compute the checksum for the complete message buffer contents.
377 msgbuf_cksum(struct msgbuf *mbp)
382 for (i = 0; i < mbp->msg_size; i++)
383 sum += (u_char)mbp->msg_ptr[i];
388 * Copy from one message buffer to another.
391 msgbuf_copy(struct msgbuf *src, struct msgbuf *dst)
395 while ((c = msgbuf_getchar(src)) >= 0)
396 msgbuf_addchar(dst, c);