1 /*- 2 * Copyright (c) 2003 Ian Dowse. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 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. 12 * 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 23 * SUCH DAMAGE. 24 * 25 * $FreeBSD$ 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 msgbuf_clear(mbp); 71 mbp->msg_magic = MSG_MAGIC; 72 mbp->msg_lastpri = -1; 73 mbp->msg_flags = 0; 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 } 125 126 /* 127 * Get a count of the number of unread characters in the message buffer. 128 */ 129 int 130 msgbuf_getcount(struct msgbuf *mbp) 131 { 132 u_int len; 133 134 len = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_rseq); 135 if (len > mbp->msg_size) 136 len = mbp->msg_size; 137 return (len); 138 } 139 140 /* 141 * Add a character into the message buffer, and update the checksum and 142 * sequence number. 143 * 144 * The caller should hold the message buffer spinlock. 145 */ 146 147 static void 148 msgbuf_do_addchar(struct msgbuf * const mbp, u_int * const seq, 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, *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); 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, &mbp->msg_wseq, c); 169 170 mtx_unlock_spin(&mbp->msg_lock); 171 } 172 173 /* 174 * Append a NUL-terminated string with a priority to a message buffer. 175 * Filter carriage returns if the caller requests it. 176 * 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? 180 */ 181 void 182 msgbuf_addstr(struct msgbuf *mbp, int pri, char *str, int filter_cr) 183 { 184 u_int seq; 185 size_t len, prefix_len; 186 char prefix[MAXPRIBUF]; 187 char buf[32]; 188 int nl, i, j, needtime; 189 190 len = strlen(str); 191 prefix_len = 0; 192 nl = 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 * Starting write sequence number. 209 */ 210 seq = mbp->msg_wseq; 211 212 /* 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. 218 */ 219 if (mbp->msg_lastpri != pri && (mbp->msg_flags & MSGBUF_NEEDNL) != 0) { 220 221 msgbuf_do_addchar(mbp, &seq, '\n'); 222 mbp->msg_flags &= ~MSGBUF_NEEDNL; 223 } 224 225 needtime = 1; 226 for (i = 0; i < len; i++) { 227 /* 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. 231 */ 232 if ((mbp->msg_flags & MSGBUF_NEEDNL) == 0 && prefix_len != 0) { 233 int j; 234 235 for (j = 0; j < prefix_len; j++) 236 msgbuf_do_addchar(mbp, &seq, prefix[j]); 237 } 238 239 if (msgbuf_show_timestamp && needtime == 1 && 240 (mbp->msg_flags & MSGBUF_NEEDNL) == 0) { 241 242 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]); 246 needtime = 0; 247 } 248 249 /* 250 * Don't copy carriage returns if the caller requested 251 * filtering. 252 * 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. 256 */ 257 if ((filter_cr != 0) && (str[i] == '\r')) 258 continue; 259 260 /* 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. 263 */ 264 if (str[i] == '\n') 265 mbp->msg_flags &= ~MSGBUF_NEEDNL; 266 else 267 mbp->msg_flags |= MSGBUF_NEEDNL; 268 269 msgbuf_do_addchar(mbp, &seq, str[i]); 270 } 271 /* 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.) 275 */ 276 mbp->msg_wseq = seq; 277 278 /* 279 * Set the last priority. 280 */ 281 mbp->msg_lastpri = pri; 282 283 mtx_unlock_spin(&mbp->msg_lock); 284 285 } 286 287 /* 288 * Read and mark as read a character from a message buffer. 289 * Returns the character, or -1 if no characters are available. 290 */ 291 int 292 msgbuf_getchar(struct msgbuf *mbp) 293 { 294 u_int len, wseq; 295 int c; 296 297 mtx_lock_spin(&mbp->msg_lock); 298 299 wseq = mbp->msg_wseq; 300 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq); 301 if (len == 0) { 302 mtx_unlock_spin(&mbp->msg_lock); 303 return (-1); 304 } 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); 309 310 mtx_unlock_spin(&mbp->msg_lock); 311 312 return (c); 313 } 314 315 /* 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'. 318 */ 319 int 320 msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen) 321 { 322 u_int len, pos, wseq; 323 324 mtx_lock_spin(&mbp->msg_lock); 325 326 wseq = mbp->msg_wseq; 327 len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq); 328 if (len == 0) { 329 mtx_unlock_spin(&mbp->msg_lock); 330 return (0); 331 } 332 if (len > mbp->msg_size) { 333 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size); 334 len = mbp->msg_size; 335 } 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); 339 340 bcopy(&mbp->msg_ptr[pos], buf, len); 341 mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + len); 342 343 mtx_unlock_spin(&mbp->msg_lock); 344 345 return (len); 346 } 347 348 /* 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. 355 * 356 * Returns the number of characters that were placed in `buf'. 357 */ 358 int 359 msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen, u_int *seqp) 360 { 361 u_int len, pos, wseq; 362 363 mtx_lock_spin(&mbp->msg_lock); 364 365 if (buf == NULL) { 366 /* Just initialise *seqp. */ 367 *seqp = MSGBUF_SEQNORM(mbp, mbp->msg_wseq - mbp->msg_size); 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_SEQNORM(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_SEQNORM(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