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 #include <sys/event.h> 41 42 #include <limits.h> 43 #include <fcntl.h> 44 #include <errno.h> 45 #include <unistd.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <err.h> 50 #include "extern.h" 51 52 static void rlines(FILE *, off_t, struct stat *); 53 54 /* defines for inner loop actions */ 55 #define USE_SLEEP 0 56 #define USE_KQUEUE 1 57 #define ADD_EVENTS 2 58 59 struct kevent *ev; 60 int action = USE_SLEEP; 61 int kq; 62 63 /* 64 * forward -- display the file, from an offset, forward. 65 * 66 * There are eight separate cases for this -- regular and non-regular 67 * files, by bytes or lines and from the beginning or end of the file. 68 * 69 * FBYTES byte offset from the beginning of the file 70 * REG seek 71 * NOREG read, counting bytes 72 * 73 * FLINES line offset from the beginning of the file 74 * REG read, counting lines 75 * NOREG read, counting lines 76 * 77 * RBYTES byte offset from the end of the file 78 * REG seek 79 * NOREG cyclically read characters into a wrap-around buffer 80 * 81 * RLINES 82 * REG mmap the file and step back until reach the correct offset. 83 * NOREG cyclically read lines into a wrap-around array of buffers 84 */ 85 void 86 forward(FILE *fp, enum STYLE style, off_t off, struct stat *sbp) 87 { 88 int ch; 89 90 switch(style) { 91 case FBYTES: 92 if (off == 0) 93 break; 94 if (S_ISREG(sbp->st_mode)) { 95 if (sbp->st_size < off) 96 off = sbp->st_size; 97 if (fseeko(fp, off, SEEK_SET) == -1) { 98 ierr(); 99 return; 100 } 101 } else while (off--) 102 if ((ch = getc(fp)) == EOF) { 103 if (ferror(fp)) { 104 ierr(); 105 return; 106 } 107 break; 108 } 109 break; 110 case FLINES: 111 if (off == 0) 112 break; 113 for (;;) { 114 if ((ch = getc(fp)) == EOF) { 115 if (ferror(fp)) { 116 ierr(); 117 return; 118 } 119 break; 120 } 121 if (ch == '\n' && !--off) 122 break; 123 } 124 break; 125 case RBYTES: 126 if (S_ISREG(sbp->st_mode)) { 127 if (sbp->st_size >= off && 128 fseeko(fp, -off, SEEK_END) == -1) { 129 ierr(); 130 return; 131 } 132 } else if (off == 0) { 133 while (getc(fp) != EOF); 134 if (ferror(fp)) { 135 ierr(); 136 return; 137 } 138 } else 139 if (display_bytes(fp, off)) 140 return; 141 break; 142 case RLINES: 143 if (S_ISREG(sbp->st_mode)) 144 if (!off) { 145 if (fseeko(fp, (off_t)0, SEEK_END) == -1) { 146 ierr(); 147 return; 148 } 149 } else 150 rlines(fp, off, sbp); 151 else if (off == 0) { 152 while (getc(fp) != EOF); 153 if (ferror(fp)) { 154 ierr(); 155 return; 156 } 157 } else 158 if (display_lines(fp, off)) 159 return; 160 break; 161 case REVERSE: 162 errx(1, "internal error: forward style cannot be REVERSE"); 163 /* NOTREACHED */ 164 } 165 166 while ((ch = getc(fp)) != EOF) { 167 if (putchar(ch) == EOF) 168 oerr(); 169 } 170 if (ferror(fp)) { 171 ierr(); 172 return; 173 } 174 fflush(stdout); 175 } 176 177 /* 178 * rlines -- display the last offset lines of the file. 179 */ 180 static void 181 rlines(FILE *fp, off_t off, struct stat *sbp) 182 { 183 struct mapinfo map; 184 off_t curoff, size; 185 int i; 186 187 if (!(size = sbp->st_size)) 188 return; 189 map.start = NULL; 190 map.fd = fileno(fp); 191 map.mapoff = map.maxoff = size; 192 193 /* 194 * Last char is special, ignore whether newline or not. Note that 195 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 196 */ 197 curoff = size - 2; 198 while (curoff >= 0) { 199 if (curoff < map.mapoff && maparound(&map, curoff) != 0) { 200 ierr(); 201 return; 202 } 203 for (i = curoff - map.mapoff; i >= 0; i--) 204 if (map.start[i] == '\n' && --off == 0) 205 break; 206 /* `i' is either the map offset of a '\n', or -1. */ 207 curoff = map.mapoff + i; 208 if (i >= 0) 209 break; 210 } 211 curoff++; 212 if (mapprint(&map, curoff, size - curoff) != 0) { 213 ierr(); 214 exit(1); 215 } 216 217 /* Set the file pointer to reflect the length displayed. */ 218 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) { 219 ierr(); 220 return; 221 } 222 if (map.start != NULL && munmap(map.start, map.maplen)) { 223 ierr(); 224 return; 225 } 226 } 227 228 /* 229 * follow -- display the file, from an offset, forward. 230 */ 231 232 static void 233 show(file_info_t *file, int at_index) 234 { 235 int ch, first; 236 237 first = 1; 238 while ((ch = getc(file->fp)) != EOF) { 239 if (first && no_files > 1) { 240 showfilename(at_index, file->file_name); 241 first = 0; 242 } 243 if (putchar(ch) == EOF) 244 oerr(); 245 } 246 fflush(stdout); 247 if (ferror(file->fp)) { 248 file->fp = NULL; 249 ierr(); 250 } else { 251 clearerr(file->fp); 252 } 253 } 254 255 void 256 showfilename(int at_index, const char *filename) 257 { 258 static int last_index = -1; 259 static int continuing = 0; 260 261 if (last_index == at_index) 262 return; 263 if (continuing) 264 printf("\n"); 265 printf("==> %s <==\n", filename); 266 continuing = 1; 267 last_index = at_index; 268 } 269 270 static void 271 set_events(file_info_t *files) 272 { 273 int i, n; 274 file_info_t *file; 275 struct timespec ts; 276 277 ts.tv_sec = 0; 278 ts.tv_nsec = 0; 279 280 n = 0; 281 action = USE_KQUEUE; 282 for (i = 0, file = files; i < no_files; i++, file++) { 283 if (file->fp == NULL) 284 continue; 285 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 286 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE, 287 EV_ADD | EV_ENABLE | EV_CLEAR, 288 NOTE_DELETE | NOTE_RENAME, 0, 0); 289 n++; 290 } 291 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ, 292 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0); 293 n++; 294 } 295 296 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) 297 action = USE_SLEEP; 298 } 299 300 void 301 follow(file_info_t *files, enum STYLE style, off_t off) 302 { 303 int active, i, n; 304 file_info_t *file; 305 struct stat sb2; 306 struct timespec ts; 307 308 /* Position each of the files */ 309 file = files; 310 active = 0; 311 n = 0; 312 for (i = 0; i < no_files; i++, file++) { 313 if (file->fp) { 314 active = 1; 315 n++; 316 if (no_files > 1) 317 showfilename(i, file->file_name); 318 forward(file->fp, style, off, &file->st); 319 if (Fflag && fileno(file->fp) != STDIN_FILENO) 320 n++; 321 } 322 } 323 324 if (!active) 325 return; 326 327 kq = kqueue(); 328 if (kq == -1) 329 err(1, "kqueue"); 330 ev = malloc(n * sizeof(struct kevent)); 331 if (ev == NULL) 332 err(1, "Couldn't allocate memory for kevents."); 333 set_events(files); 334 335 for (;;) { 336 for (i = 0, file = files; i < no_files; i++, file++) { 337 if (file->fp == NULL) 338 continue; 339 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 340 if (stat(file->file_name, &sb2) == -1) { 341 /* 342 * file was rotated, skip it until it 343 * reappears. 344 */ 345 continue; 346 } 347 if (sb2.st_ino != file->st.st_ino || 348 sb2.st_dev != file->st.st_dev || 349 sb2.st_nlink == 0) { 350 file->fp = freopen(file->file_name, "r", 351 file->fp); 352 if (file->fp == NULL) { 353 ierr(); 354 continue; 355 } else { 356 memcpy(&file->st, &sb2, 357 sizeof(struct stat)); 358 set_events(files); 359 } 360 } 361 } 362 show(file, i); 363 } 364 365 switch (action) { 366 case USE_KQUEUE: 367 ts.tv_sec = 1; 368 ts.tv_nsec = 0; 369 /* 370 * In the -F case, we set a timeout to ensure that 371 * we re-stat the file at least once every second. 372 */ 373 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL); 374 if (n == -1) 375 err(1, "kevent"); 376 if (n == 0) { 377 /* timeout */ 378 break; 379 } else if (ev->filter == EVFILT_READ && ev->data < 0) { 380 /* file shrank, reposition to end */ 381 if (lseek(ev->ident, 0, SEEK_END) == -1) { 382 ierr(); 383 continue; 384 } 385 } 386 break; 387 388 case USE_SLEEP: 389 usleep(250000); 390 break; 391 } 392 } 393 } 394