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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)forward.c 8.1 (Berkeley) 6/6/93 37 * $FreeBSD: src/usr.bin/tail/forward.c,v 1.11.6.7 2003/01/07 05:26:22 tjr Exp $ 38 */ 39 40 #include <sys/types.h> 41 #include <sys/stat.h> 42 #include <sys/time.h> 43 #include <sys/mman.h> 44 #include <sys/event.h> 45 46 #include <limits.h> 47 #include <fcntl.h> 48 #include <errno.h> 49 #include <unistd.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <err.h> 54 #include "extern.h" 55 56 static void rlines(FILE *, off_t, struct stat *); 57 58 /* defines for inner loop actions */ 59 #define USE_SLEEP 0 60 #define USE_KQUEUE 1 61 #define ADD_EVENTS 2 62 63 struct kevent *ev; 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 */ 235 236 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 } 258 259 void 260 showfilename(int at_index, const char *filename) 261 { 262 static int last_index = -1; 263 static int continuing = 0; 264 265 if (last_index == at_index) 266 return; 267 if (continuing) 268 printf("\n"); 269 printf("==> %s <==\n", filename); 270 continuing = 1; 271 last_index = at_index; 272 } 273 274 static void 275 set_events(file_info_t *files) 276 { 277 int i, n; 278 file_info_t *file; 279 struct timespec ts; 280 281 ts.tv_sec = 0; 282 ts.tv_nsec = 0; 283 284 n = 0; 285 action = USE_KQUEUE; 286 for (i = 0, file = files; i < no_files; i++, file++) { 287 if (file->fp == NULL) 288 continue; 289 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 290 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE, 291 EV_ADD | EV_ENABLE | EV_CLEAR, 292 NOTE_DELETE | NOTE_RENAME, 0, 0); 293 n++; 294 } 295 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ, 296 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0); 297 n++; 298 } 299 300 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) 301 action = USE_SLEEP; 302 } 303 304 void 305 follow(file_info_t *files, enum STYLE style, off_t off) 306 { 307 int active, i, n; 308 file_info_t *file; 309 struct stat sb2; 310 struct timespec ts; 311 312 /* Position each of the files */ 313 file = files; 314 active = 0; 315 n = 0; 316 for (i = 0; i < no_files; i++, file++) { 317 if (file->fp) { 318 active = 1; 319 n++; 320 if (no_files > 1) 321 showfilename(i, file->file_name); 322 forward(file->fp, style, off, &file->st); 323 if (Fflag && fileno(file->fp) != STDIN_FILENO) 324 n++; 325 } 326 } 327 328 if (!active) 329 return; 330 331 kq = kqueue(); 332 if (kq == -1) 333 err(1, "kqueue"); 334 ev = malloc(n * sizeof(struct kevent)); 335 if (ev == NULL) 336 err(1, "Couldn't allocate memory for kevents."); 337 set_events(files); 338 339 for (;;) { 340 for (i = 0, file = files; i < no_files; i++, file++) { 341 if (file->fp == NULL) 342 continue; 343 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 344 if (stat(file->file_name, &sb2) == -1) { 345 /* 346 * file was rotated, skip it until it 347 * reappears. 348 */ 349 continue; 350 } 351 if (sb2.st_ino != file->st.st_ino || 352 sb2.st_dev != file->st.st_dev || 353 sb2.st_nlink == 0) { 354 file->fp = freopen(file->file_name, "r", 355 file->fp); 356 if (file->fp == NULL) { 357 ierr(); 358 continue; 359 } else { 360 memcpy(&file->st, &sb2, 361 sizeof(struct stat)); 362 set_events(files); 363 } 364 } 365 } 366 show(file, i); 367 } 368 369 switch (action) { 370 case USE_KQUEUE: 371 ts.tv_sec = 1; 372 ts.tv_nsec = 0; 373 /* 374 * In the -F case, we set a timeout to ensure that 375 * we re-stat the file at least once every second. 376 */ 377 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL); 378 if (n == -1) 379 err(1, "kevent"); 380 if (n == 0) { 381 /* timeout */ 382 break; 383 } else if (ev->filter == EVFILT_READ && ev->data < 0) { 384 /* file shrank, reposition to end */ 385 if (lseek(ev->ident, 0, SEEK_END) == -1) { 386 ierr(); 387 continue; 388 } 389 } 390 break; 391 392 case USE_SLEEP: 393 usleep(250000); 394 break; 395 } 396 } 397 } 398