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