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 snprintf(buf, sizeof(buf), "[%jd] ", 238 (intmax_t)time_uptime); 239 for (j = 0; buf[j] != '\0'; j++) 240 msgbuf_do_addchar(mbp, buf[j]); 241 needtime = 0; 242 } 243 244 /* 245 * Don't copy carriage returns if the caller requested 246 * filtering. 247 * 248 * XXX This matches the behavior of msglogchar(), but is it 249 * necessary? Testing has shown that we don't seem to get 250 * carriage returns here. 251 */ 252 if ((filter_cr != 0) && (str[i] == '\r')) 253 continue; 254 255 /* 256 * Clear this flag if we see a newline. This affects whether 257 * we need to insert a new prefix or insert a newline later. 258 */ 259 if (str[i] == '\n') 260 mbp->msg_flags &= ~MSGBUF_NEEDNL; 261 else 262 mbp->msg_flags |= MSGBUF_NEEDNL; 263 264 msgbuf_do_addchar(mbp, str[i]); 265 } 266 if (mbp->msg_wseq >= mbp->msg_size) 267 mbp->msg_flags |= MSGBUF_WRAP; 268 269 /* 270 * Set the last priority. 271 */ 272 mbp->msg_lastpri = pri; 273 274 mtx_unlock_spin(&mbp->msg_lock); 275 276 } 277 278 /* 279 * Read and mark as read a character from a message buffer. 280 * Returns the character, or -1 if no characters are available. 281 */ 282 int 283 msgbuf_getchar(struct msgbuf *mbp) 284 { 285 u_int len, wseq; 286 int c; 287 288 mtx_lock_spin(&mbp->msg_lock); 289 290 wseq = mbp->msg_wseq; 291 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq); 292 if (len == 0) { 293 mtx_unlock_spin(&mbp->msg_lock); 294 return (-1); 295 } 296 if (len > mbp->msg_size) 297 mbp->msg_rseq = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size); 298 c = (u_char)mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq)]; 299 mbp->msg_rseq = MSGBUF_SEQADD(mbp, mbp->msg_rseq, 1); 300 301 mtx_unlock_spin(&mbp->msg_lock); 302 303 return (c); 304 } 305 306 /* 307 * Read and mark as read a number of characters from a message buffer. 308 * Returns the number of characters that were placed in `buf'. 309 */ 310 int 311 msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen) 312 { 313 u_int len, pos, wseq; 314 315 mtx_lock_spin(&mbp->msg_lock); 316 317 wseq = mbp->msg_wseq; 318 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq); 319 if (len == 0) { 320 mtx_unlock_spin(&mbp->msg_lock); 321 return (0); 322 } 323 if (len > mbp->msg_size) { 324 mbp->msg_rseq = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size); 325 len = mbp->msg_size; 326 } 327 pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq); 328 len = min(len, mbp->msg_size - pos); 329 len = min(len, (u_int)buflen); 330 331 bcopy(&mbp->msg_ptr[pos], buf, len); 332 mbp->msg_rseq = MSGBUF_SEQADD(mbp, mbp->msg_rseq, len); 333 334 mtx_unlock_spin(&mbp->msg_lock); 335 336 return (len); 337 } 338 339 /* 340 * Peek at the full contents of a message buffer without marking any 341 * data as read. `seqp' should point to an unsigned integer that 342 * msgbuf_peekbytes() can use to retain state between calls so that 343 * the whole message buffer can be read in multiple short reads. 344 * To initialise this variable to the start of the message buffer, 345 * call msgbuf_peekbytes() with a NULL `buf' parameter. 346 * 347 * Returns the number of characters that were placed in `buf'. 348 */ 349 int 350 msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen, u_int *seqp) 351 { 352 u_int len, pos, wseq; 353 354 mtx_lock_spin(&mbp->msg_lock); 355 356 if (buf == NULL) { 357 /* Just initialise *seqp. */ 358 if (mbp->msg_flags & MSGBUF_WRAP) 359 *seqp = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_size); 360 else 361 *seqp = 0; 362 mtx_unlock_spin(&mbp->msg_lock); 363 return (0); 364 } 365 366 wseq = mbp->msg_wseq; 367 len = MSGBUF_SEQSUB(mbp, wseq, *seqp); 368 if (len == 0) { 369 mtx_unlock_spin(&mbp->msg_lock); 370 return (0); 371 } 372 if (len > mbp->msg_size) { 373 *seqp = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size); 374 len = mbp->msg_size; 375 } 376 pos = MSGBUF_SEQ_TO_POS(mbp, *seqp); 377 len = min(len, mbp->msg_size - pos); 378 len = min(len, (u_int)buflen); 379 bcopy(&mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, *seqp)], buf, len); 380 *seqp = MSGBUF_SEQADD(mbp, *seqp, len); 381 382 mtx_unlock_spin(&mbp->msg_lock); 383 384 return (len); 385 } 386 387 /* 388 * Compute the checksum for the complete message buffer contents. 389 */ 390 static u_int 391 msgbuf_cksum(struct msgbuf *mbp) 392 { 393 u_int i, sum; 394 395 sum = 0; 396 for (i = 0; i < mbp->msg_size; i++) 397 sum += (u_char)mbp->msg_ptr[i]; 398 return (sum); 399 } 400 401 /* 402 * Copy from one message buffer to another. 403 */ 404 void 405 msgbuf_copy(struct msgbuf *src, struct msgbuf *dst) 406 { 407 int c; 408 409 while ((c = msgbuf_getchar(src)) >= 0) 410 msgbuf_addchar(dst, c); 411 } 412 413 /* 414 * Get a snapshot of the message buffer, without modifying its internal state 415 * (i.e. don't mark any new characters as read). 416 */ 417 void 418 msgbuf_duplicate(struct msgbuf *src, struct msgbuf *dst, char *dst_msgptr) 419 { 420 421 mtx_lock_spin(&src->msg_lock); 422 bcopy(src, dst, sizeof(struct msgbuf)); 423 dst->msg_ptr = dst_msgptr; 424 bcopy(src->msg_ptr, dst->msg_ptr, src->msg_size); 425 mtx_unlock_spin(&src->msg_lock); 426 } 427