1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Edward Sze-Tyan Wang. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)forward.c 8.1 (Berkeley) 6/6/93 33 * $FreeBSD: src/usr.bin/tail/forward.c,v 1.11.6.7 2003/01/07 05:26:22 tjr Exp $ 34 */ 35 36 #include <sys/types.h> 37 #include <sys/stat.h> 38 #include <sys/time.h> 39 #include <sys/mman.h> 40 #ifndef BOOTSTRAPPING 41 #include <sys/event.h> 42 #endif 43 44 #include <limits.h> 45 #include <fcntl.h> 46 #include <errno.h> 47 #include <unistd.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <err.h> 52 #include "extern.h" 53 54 static void rlines(FILE *, off_t, struct stat *); 55 56 /* defines for inner loop actions */ 57 #define USE_SLEEP 0 58 #ifndef BOOTSTRAPPING 59 #define USE_KQUEUE 1 60 #define ADD_EVENTS 2 61 62 struct kevent *ev; 63 #endif 64 int action = USE_SLEEP; 65 int kq; 66 67 /* 68 * forward -- display the file, from an offset, forward. 69 * 70 * There are eight separate cases for this -- regular and non-regular 71 * files, by bytes or lines and from the beginning or end of the file. 72 * 73 * FBYTES byte offset from the beginning of the file 74 * REG seek 75 * NOREG read, counting bytes 76 * 77 * FLINES line offset from the beginning of the file 78 * REG read, counting lines 79 * NOREG read, counting lines 80 * 81 * RBYTES byte offset from the end of the file 82 * REG seek 83 * NOREG cyclically read characters into a wrap-around buffer 84 * 85 * RLINES 86 * REG mmap the file and step back until reach the correct offset. 87 * NOREG cyclically read lines into a wrap-around array of buffers 88 */ 89 void 90 forward(FILE *fp, enum STYLE style, off_t off, struct stat *sbp) 91 { 92 int ch; 93 94 switch(style) { 95 case FBYTES: 96 if (off == 0) 97 break; 98 if (S_ISREG(sbp->st_mode)) { 99 if (sbp->st_size < off) 100 off = sbp->st_size; 101 if (fseeko(fp, off, SEEK_SET) == -1) { 102 ierr(); 103 return; 104 } 105 } else while (off--) 106 if ((ch = getc(fp)) == EOF) { 107 if (ferror(fp)) { 108 ierr(); 109 return; 110 } 111 break; 112 } 113 break; 114 case FLINES: 115 if (off == 0) 116 break; 117 for (;;) { 118 if ((ch = getc(fp)) == EOF) { 119 if (ferror(fp)) { 120 ierr(); 121 return; 122 } 123 break; 124 } 125 if (ch == '\n' && !--off) 126 break; 127 } 128 break; 129 case RBYTES: 130 if (S_ISREG(sbp->st_mode)) { 131 if (sbp->st_size >= off && 132 fseeko(fp, -off, SEEK_END) == -1) { 133 ierr(); 134 return; 135 } 136 } else if (off == 0) { 137 while (getc(fp) != EOF); 138 if (ferror(fp)) { 139 ierr(); 140 return; 141 } 142 } else 143 if (display_bytes(fp, off)) 144 return; 145 break; 146 case RLINES: 147 if (S_ISREG(sbp->st_mode)) 148 if (!off) { 149 if (fseeko(fp, (off_t)0, SEEK_END) == -1) { 150 ierr(); 151 return; 152 } 153 } else 154 rlines(fp, off, sbp); 155 else if (off == 0) { 156 while (getc(fp) != EOF); 157 if (ferror(fp)) { 158 ierr(); 159 return; 160 } 161 } else 162 if (display_lines(fp, off)) 163 return; 164 break; 165 case REVERSE: 166 errx(1, "internal error: forward style cannot be REVERSE"); 167 /* NOTREACHED */ 168 } 169 170 while ((ch = getc(fp)) != EOF) { 171 if (putchar(ch) == EOF) 172 oerr(); 173 } 174 if (ferror(fp)) { 175 ierr(); 176 return; 177 } 178 fflush(stdout); 179 } 180 181 /* 182 * rlines -- display the last offset lines of the file. 183 */ 184 static void 185 rlines(FILE *fp, off_t off, struct stat *sbp) 186 { 187 struct mapinfo map; 188 off_t curoff, size; 189 int i; 190 191 if (!(size = sbp->st_size)) 192 return; 193 map.start = NULL; 194 map.fd = fileno(fp); 195 map.mapoff = map.maxoff = size; 196 197 /* 198 * Last char is special, ignore whether newline or not. Note that 199 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 200 */ 201 curoff = size - 2; 202 while (curoff >= 0) { 203 if (curoff < map.mapoff && maparound(&map, curoff) != 0) { 204 ierr(); 205 return; 206 } 207 for (i = curoff - map.mapoff; i >= 0; i--) 208 if (map.start[i] == '\n' && --off == 0) 209 break; 210 /* `i' is either the map offset of a '\n', or -1. */ 211 curoff = map.mapoff + i; 212 if (i >= 0) 213 break; 214 } 215 curoff++; 216 if (mapprint(&map, curoff, size - curoff) != 0) { 217 ierr(); 218 exit(1); 219 } 220 221 /* Set the file pointer to reflect the length displayed. */ 222 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) { 223 ierr(); 224 return; 225 } 226 if (map.start != NULL && munmap(map.start, map.maplen)) { 227 ierr(); 228 return; 229 } 230 } 231 232 /* 233 * follow -- display the file, from an offset, forward. 234 */ 235 #ifndef BOOTSTRAPPING 236 static void 237 show(file_info_t *file, int at_index) 238 { 239 int ch, first; 240 241 first = 1; 242 while ((ch = getc(file->fp)) != EOF) { 243 if (first && no_files > 1) { 244 showfilename(at_index, file->file_name); 245 first = 0; 246 } 247 if (putchar(ch) == EOF) 248 oerr(); 249 } 250 fflush(stdout); 251 if (ferror(file->fp)) { 252 file->fp = NULL; 253 ierr(); 254 } else { 255 clearerr(file->fp); 256 } 257 } 258 #endif 259 260 void 261 showfilename(int at_index, const char *filename) 262 { 263 static int last_index = -1; 264 static int continuing = 0; 265 266 if (last_index == at_index) 267 return; 268 if (!qflag) { 269 if (continuing) 270 printf("\n"); 271 printf("==> %s <==\n", filename); 272 } 273 continuing = 1; 274 last_index = at_index; 275 } 276 277 #ifndef BOOTSTRAPPING 278 static void 279 set_events(file_info_t *files) 280 { 281 int i, n; 282 file_info_t *file; 283 struct timespec ts; 284 285 ts.tv_sec = 0; 286 ts.tv_nsec = 0; 287 288 n = 0; 289 action = USE_KQUEUE; 290 for (i = 0, file = files; i < no_files; i++, file++) { 291 if (file->fp == NULL) 292 continue; 293 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 294 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE, 295 EV_ADD | EV_ENABLE | EV_CLEAR, 296 NOTE_DELETE | NOTE_RENAME, 0, 0); 297 n++; 298 } 299 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ, 300 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0); 301 n++; 302 } 303 304 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) 305 action = USE_SLEEP; 306 } 307 308 void 309 follow(file_info_t *files, enum STYLE style, off_t off) 310 { 311 int active, i, n; 312 file_info_t *file; 313 struct stat sb2; 314 struct timespec ts; 315 316 /* Position each of the files */ 317 file = files; 318 active = 0; 319 n = 0; 320 for (i = 0; i < no_files; i++, file++) { 321 if (file->fp) { 322 active = 1; 323 n++; 324 if (no_files > 1) 325 showfilename(i, file->file_name); 326 forward(file->fp, style, off, &file->st); 327 if (Fflag && fileno(file->fp) != STDIN_FILENO) 328 n++; 329 } 330 } 331 332 if (!active) 333 return; 334 335 kq = kqueue(); 336 if (kq == -1) 337 err(1, "kqueue"); 338 ev = malloc(n * sizeof(struct kevent)); 339 if (ev == NULL) 340 err(1, "Couldn't allocate memory for kevents."); 341 set_events(files); 342 343 for (;;) { 344 for (i = 0, file = files; i < no_files; i++, file++) { 345 if (file->fp == NULL) 346 continue; 347 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 348 if (stat(file->file_name, &sb2) == -1) { 349 /* 350 * file was rotated, skip it until it 351 * reappears. 352 */ 353 continue; 354 } 355 if (sb2.st_ino != file->st.st_ino || 356 sb2.st_dev != file->st.st_dev || 357 sb2.st_nlink == 0) { 358 file->fp = freopen(file->file_name, "r", 359 file->fp); 360 if (file->fp == NULL) { 361 ierr(); 362 continue; 363 } else { 364 memcpy(&file->st, &sb2, 365 sizeof(struct stat)); 366 set_events(files); 367 } 368 } 369 } 370 show(file, i); 371 } 372 373 switch (action) { 374 case USE_KQUEUE: 375 ts.tv_sec = 1; 376 ts.tv_nsec = 0; 377 /* 378 * In the -F case, we set a timeout to ensure that 379 * we re-stat the file at least once every second. 380 */ 381 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL); 382 if (n == -1) 383 err(1, "kevent"); 384 if (n == 0) { 385 /* timeout */ 386 break; 387 } else if (ev->filter == EVFILT_READ && ev->data < 0) { 388 /* file shrank, reposition to end */ 389 if (lseek(ev->ident, 0, SEEK_END) == -1) { 390 ierr(); 391 continue; 392 } 393 } 394 break; 395 396 case USE_SLEEP: 397 usleep(250000); 398 break; 399 } 400 } 401 } 402 #endif 403