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 } 435