1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Edward Sze-Tyan Wang. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 37 __FBSDID("$FreeBSD$"); 38 39 #ifndef lint 40 static const char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93"; 41 #endif 42 43 #include <sys/param.h> 44 #include <sys/mount.h> 45 #include <sys/types.h> 46 #include <sys/stat.h> 47 #include <sys/time.h> 48 #include <sys/mman.h> 49 #include <sys/event.h> 50 51 #include <err.h> 52 #include <errno.h> 53 #include <fcntl.h> 54 #include <limits.h> 55 #include <stdio.h> 56 #include <stdlib.h> 57 #include <string.h> 58 #include <unistd.h> 59 60 #include <libcasper.h> 61 #include <casper/cap_fileargs.h> 62 63 #include "extern.h" 64 65 static void rlines(FILE *, const char *fn, off_t, struct stat *); 66 static int show(file_info_t *); 67 static void set_events(file_info_t *files); 68 69 /* defines for inner loop actions */ 70 #define USE_SLEEP 0 71 #define USE_KQUEUE 1 72 #define ADD_EVENTS 2 73 74 static struct kevent *ev; 75 static int action = USE_SLEEP; 76 static int kq; 77 78 static const file_info_t *last; 79 80 /* 81 * forward -- display the file, from an offset, forward. 82 * 83 * There are eight separate cases for this -- regular and non-regular 84 * files, by bytes or lines and from the beginning or end of the file. 85 * 86 * FBYTES byte offset from the beginning of the file 87 * REG seek 88 * NOREG read, counting bytes 89 * 90 * FLINES line offset from the beginning of the file 91 * REG read, counting lines 92 * NOREG read, counting lines 93 * 94 * RBYTES byte offset from the end of the file 95 * REG seek 96 * NOREG cyclically read characters into a wrap-around buffer 97 * 98 * RLINES 99 * REG mmap the file and step back until reach the correct offset. 100 * NOREG cyclically read lines into a wrap-around array of buffers 101 */ 102 void 103 forward(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 104 { 105 int ch; 106 107 switch(style) { 108 case FBYTES: 109 if (off == 0) 110 break; 111 if (S_ISREG(sbp->st_mode)) { 112 if (sbp->st_size < off) 113 off = sbp->st_size; 114 if (fseeko(fp, off, SEEK_SET) == -1) { 115 ierr(fn); 116 return; 117 } 118 } else while (off--) 119 if ((ch = getc(fp)) == EOF) { 120 if (ferror(fp)) { 121 ierr(fn); 122 return; 123 } 124 break; 125 } 126 break; 127 case FLINES: 128 if (off == 0) 129 break; 130 for (;;) { 131 if ((ch = getc(fp)) == EOF) { 132 if (ferror(fp)) { 133 ierr(fn); 134 return; 135 } 136 break; 137 } 138 if (ch == '\n' && !--off) 139 break; 140 } 141 break; 142 case RBYTES: 143 if (S_ISREG(sbp->st_mode)) { 144 if (sbp->st_size >= off && 145 fseeko(fp, -off, SEEK_END) == -1) { 146 ierr(fn); 147 return; 148 } 149 } else if (off == 0) { 150 while (getc(fp) != EOF); 151 if (ferror(fp)) { 152 ierr(fn); 153 return; 154 } 155 } else 156 if (bytes(fp, fn, off)) 157 return; 158 break; 159 case RLINES: 160 if (S_ISREG(sbp->st_mode)) 161 if (!off) { 162 if (fseeko(fp, (off_t)0, SEEK_END) == -1) { 163 ierr(fn); 164 return; 165 } 166 } else 167 rlines(fp, fn, off, sbp); 168 else if (off == 0) { 169 while (getc(fp) != EOF); 170 if (ferror(fp)) { 171 ierr(fn); 172 return; 173 } 174 } else 175 if (lines(fp, fn, off)) 176 return; 177 break; 178 default: 179 break; 180 } 181 182 while ((ch = getc(fp)) != EOF) 183 if (putchar(ch) == EOF) 184 oerr(); 185 if (ferror(fp)) { 186 ierr(fn); 187 return; 188 } 189 (void)fflush(stdout); 190 } 191 192 /* 193 * rlines -- display the last offset lines of the file. 194 */ 195 static void 196 rlines(FILE *fp, const char *fn, off_t off, struct stat *sbp) 197 { 198 struct mapinfo map; 199 off_t curoff, size; 200 int i; 201 202 if (!(size = sbp->st_size)) 203 return; 204 map.start = NULL; 205 map.fd = fileno(fp); 206 map.mapoff = map.maxoff = size; 207 208 /* 209 * Last char is special, ignore whether newline or not. Note that 210 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 211 */ 212 curoff = size - 2; 213 while (curoff >= 0) { 214 if (curoff < map.mapoff && maparound(&map, curoff) != 0) { 215 ierr(fn); 216 return; 217 } 218 for (i = curoff - map.mapoff; i >= 0; i--) 219 if (map.start[i] == '\n' && --off == 0) 220 break; 221 /* `i' is either the map offset of a '\n', or -1. */ 222 curoff = map.mapoff + i; 223 if (i >= 0) 224 break; 225 } 226 curoff++; 227 if (mapprint(&map, curoff, size - curoff) != 0) { 228 ierr(fn); 229 exit(1); 230 } 231 232 /* Set the file pointer to reflect the length displayed. */ 233 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) { 234 ierr(fn); 235 return; 236 } 237 if (map.start != NULL && munmap(map.start, map.maplen)) { 238 ierr(fn); 239 return; 240 } 241 } 242 243 static int 244 show(file_info_t *file) 245 { 246 int ch; 247 248 while ((ch = getc(file->fp)) != EOF) { 249 if (last != file && no_files > 1) { 250 if (!qflag) 251 printfn(file->file_name, 1); 252 last = file; 253 } 254 if (putchar(ch) == EOF) 255 oerr(); 256 } 257 (void)fflush(stdout); 258 if (ferror(file->fp)) { 259 fclose(file->fp); 260 file->fp = NULL; 261 ierr(file->file_name); 262 return 0; 263 } 264 clearerr(file->fp); 265 return 1; 266 } 267 268 static void 269 set_events(file_info_t *files) 270 { 271 int i, n = 0; 272 file_info_t *file; 273 struct timespec ts; 274 struct statfs sf; 275 276 ts.tv_sec = 0; 277 ts.tv_nsec = 0; 278 279 action = USE_KQUEUE; 280 for (i = 0, file = files; i < no_files; i++, file++) { 281 if (! file->fp) 282 continue; 283 284 if (fstatfs(fileno(file->fp), &sf) == 0 && 285 (sf.f_flags & MNT_LOCAL) == 0) { 286 action = USE_SLEEP; 287 return; 288 } 289 290 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 291 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE, 292 EV_ADD | EV_ENABLE | EV_CLEAR, 293 NOTE_DELETE | NOTE_RENAME, 0, 0); 294 n++; 295 } 296 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ, 297 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0); 298 n++; 299 } 300 301 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) { 302 action = USE_SLEEP; 303 } 304 } 305 306 /* 307 * follow -- display the file, from an offset, forward. 308 * 309 */ 310 void 311 follow(file_info_t *files, enum STYLE style, off_t off) 312 { 313 int active, ev_change, i, n = -1; 314 struct stat sb2; 315 file_info_t *file; 316 FILE *ftmp; 317 struct timespec ts; 318 319 /* Position each of the files */ 320 321 file = files; 322 active = 0; 323 n = 0; 324 for (i = 0; i < no_files; i++, file++) { 325 if (file->fp) { 326 active = 1; 327 n++; 328 if (no_files > 1 && !qflag) 329 printfn(file->file_name, 1); 330 forward(file->fp, file->file_name, style, off, &file->st); 331 if (Fflag && fileno(file->fp) != STDIN_FILENO) 332 n++; 333 } 334 } 335 if (!Fflag && !active) 336 return; 337 338 last = --file; 339 340 kq = kqueue(); 341 if (kq < 0) 342 err(1, "kqueue"); 343 ev = malloc(n * sizeof(struct kevent)); 344 if (! ev) 345 err(1, "Couldn't allocate memory for kevents."); 346 set_events(files); 347 348 for (;;) { 349 ev_change = 0; 350 if (Fflag) { 351 for (i = 0, file = files; i < no_files; i++, file++) { 352 if (!file->fp) { 353 file->fp = 354 fileargs_fopen(fa, file->file_name, 355 "r"); 356 if (file->fp != NULL && 357 fstat(fileno(file->fp), &file->st) 358 == -1) { 359 fclose(file->fp); 360 file->fp = NULL; 361 } 362 if (file->fp != NULL) 363 ev_change++; 364 continue; 365 } 366 if (fileno(file->fp) == STDIN_FILENO) 367 continue; 368 ftmp = fileargs_fopen(fa, file->file_name, "r"); 369 if (ftmp == NULL || 370 fstat(fileno(file->fp), &sb2) == -1) { 371 if (errno != ENOENT) 372 ierr(file->file_name); 373 show(file); 374 if (file->fp != NULL) { 375 fclose(file->fp); 376 file->fp = NULL; 377 } 378 if (ftmp != NULL) { 379 fclose(ftmp); 380 } 381 ev_change++; 382 continue; 383 } 384 385 if (sb2.st_ino != file->st.st_ino || 386 sb2.st_dev != file->st.st_dev || 387 sb2.st_nlink == 0) { 388 show(file); 389 fclose(file->fp); 390 file->fp = ftmp; 391 memcpy(&file->st, &sb2, 392 sizeof(struct stat)); 393 ev_change++; 394 } else { 395 fclose(ftmp); 396 } 397 } 398 } 399 400 for (i = 0, file = files; i < no_files; i++, file++) 401 if (file->fp && !show(file)) 402 ev_change++; 403 404 if (ev_change) 405 set_events(files); 406 407 switch (action) { 408 case USE_KQUEUE: 409 ts.tv_sec = 1; 410 ts.tv_nsec = 0; 411 /* 412 * In the -F case we set a timeout to ensure that 413 * we re-stat the file at least once every second. 414 */ 415 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL); 416 if (n < 0) 417 err(1, "kevent"); 418 if (n == 0) { 419 /* timeout */ 420 break; 421 } else if (ev->filter == EVFILT_READ && ev->data < 0) { 422 /* file shrank, reposition to end */ 423 if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) { 424 ierr(file->file_name); 425 continue; 426 } 427 } 428 break; 429 430 case USE_SLEEP: 431 (void) usleep(250000); 432 break; 433 } 434 } 435 } 436