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 36 37 #include <sys/param.h> 38 #include <sys/mount.h> 39 #include <sys/types.h> 40 #include <sys/stat.h> 41 #include <sys/time.h> 42 #include <sys/mman.h> 43 #include <sys/event.h> 44 45 #include <err.h> 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <limits.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <unistd.h> 53 54 #include <libcasper.h> 55 #include <casper/cap_fileargs.h> 56 57 #include "extern.h" 58 59 static void rlines(FILE *, const char *fn, off_t, struct stat *); 60 static int show(file_info_t *); 61 static void set_events(file_info_t *files); 62 63 /* defines for inner loop actions */ 64 #define USE_SLEEP 0 65 #define USE_KQUEUE 1 66 #define ADD_EVENTS 2 67 68 static struct kevent *ev; 69 static int action = USE_SLEEP; 70 static int kq; 71 72 static const file_info_t *last; 73 74 /* 75 * forward -- display the file, from an offset, forward. 76 * 77 * There are eight separate cases for this -- regular and non-regular 78 * files, by bytes or lines and from the beginning or end of the file. 79 * 80 * FBYTES byte offset from the beginning of the file 81 * REG seek 82 * NOREG read, counting bytes 83 * 84 * FLINES line offset from the beginning of the file 85 * REG read, counting lines 86 * NOREG read, counting lines 87 * 88 * RBYTES byte offset from the end of the file 89 * REG seek 90 * NOREG cyclically read characters into a wrap-around buffer 91 * 92 * RLINES 93 * REG mmap the file and step back until reach the correct offset. 94 * NOREG cyclically read lines into a wrap-around array of buffers 95 */ 96 void 97 forward(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 98 { 99 int ch; 100 101 switch(style) { 102 case FBYTES: 103 if (off == 0) 104 break; 105 if (S_ISREG(sbp->st_mode) && sbp->st_size > 0) { 106 if (sbp->st_size < off) 107 off = sbp->st_size; 108 if (fseeko(fp, off, SEEK_SET) == -1) { 109 ierr(fn); 110 return; 111 } 112 } else while (off--) 113 if ((ch = getc(fp)) == EOF) { 114 if (ferror(fp)) { 115 ierr(fn); 116 return; 117 } 118 break; 119 } 120 break; 121 case FLINES: 122 if (off == 0) 123 break; 124 for (;;) { 125 if ((ch = getc(fp)) == EOF) { 126 if (ferror(fp)) { 127 ierr(fn); 128 return; 129 } 130 break; 131 } 132 if (ch == '\n' && !--off) 133 break; 134 } 135 break; 136 case RBYTES: 137 if (S_ISREG(sbp->st_mode) && sbp->st_size > 0) { 138 if (sbp->st_size >= off && 139 fseeko(fp, -off, SEEK_END) == -1) { 140 ierr(fn); 141 return; 142 } 143 } else if (off == 0) { 144 while (getc(fp) != EOF); 145 if (ferror(fp)) { 146 ierr(fn); 147 return; 148 } 149 } else 150 if (bytes(fp, fn, off)) 151 return; 152 break; 153 case RLINES: 154 if (S_ISREG(sbp->st_mode) && sbp->st_size > 0) 155 if (!off) { 156 if (fseeko(fp, (off_t)0, SEEK_END) == -1) { 157 ierr(fn); 158 return; 159 } 160 } else 161 rlines(fp, fn, off, sbp); 162 else if (off == 0) { 163 while (getc(fp) != EOF); 164 if (ferror(fp)) { 165 ierr(fn); 166 return; 167 } 168 } else 169 if (lines(fp, fn, off)) 170 return; 171 break; 172 default: 173 break; 174 } 175 176 while ((ch = getc(fp)) != EOF) 177 if (putchar(ch) == EOF) 178 oerr(); 179 if (ferror(fp)) { 180 ierr(fn); 181 return; 182 } 183 (void)fflush(stdout); 184 } 185 186 /* 187 * rlines -- display the last offset lines of the file. 188 */ 189 static void 190 rlines(FILE *fp, const char *fn, off_t off, struct stat *sbp) 191 { 192 struct mapinfo map; 193 off_t curoff, size; 194 int i; 195 196 if (!(size = sbp->st_size)) 197 return; 198 map.start = NULL; 199 map.fd = fileno(fp); 200 map.mapoff = map.maxoff = size; 201 202 /* 203 * Last char is special, ignore whether newline or not. Note that 204 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 205 */ 206 curoff = size - 2; 207 while (curoff >= 0) { 208 if (curoff < map.mapoff && maparound(&map, curoff) != 0) { 209 ierr(fn); 210 return; 211 } 212 for (i = curoff - map.mapoff; i >= 0; i--) 213 if (map.start[i] == '\n' && --off == 0) 214 break; 215 /* `i' is either the map offset of a '\n', or -1. */ 216 curoff = map.mapoff + i; 217 if (i >= 0) 218 break; 219 } 220 curoff++; 221 if (mapprint(&map, curoff, size - curoff) != 0) { 222 ierr(fn); 223 exit(1); 224 } 225 226 /* Set the file pointer to reflect the length displayed. */ 227 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) { 228 ierr(fn); 229 return; 230 } 231 if (map.start != NULL && munmap(map.start, map.maplen)) { 232 ierr(fn); 233 return; 234 } 235 } 236 237 static int 238 show(file_info_t *file) 239 { 240 int ch; 241 242 while ((ch = getc(file->fp)) != EOF) { 243 if (last != file) { 244 if (vflag || (qflag == 0 && no_files > 1)) 245 printfn(file->file_name, 1); 246 last = file; 247 } 248 if (putchar(ch) == EOF) 249 oerr(); 250 } 251 (void)fflush(stdout); 252 if (ferror(file->fp)) { 253 fclose(file->fp); 254 file->fp = NULL; 255 ierr(file->file_name); 256 return 0; 257 } 258 clearerr(file->fp); 259 return 1; 260 } 261 262 static void 263 set_events(file_info_t *files) 264 { 265 int i, n = 0; 266 file_info_t *file; 267 struct timespec ts; 268 struct statfs sf; 269 270 ts.tv_sec = 0; 271 ts.tv_nsec = 0; 272 273 action = USE_KQUEUE; 274 for (i = 0, file = files; i < no_files; i++, file++) { 275 if (!file->fp) 276 continue; 277 278 if (fstatfs(fileno(file->fp), &sf) == 0 && 279 (sf.f_flags & MNT_LOCAL) == 0) { 280 action = USE_SLEEP; 281 return; 282 } 283 284 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 285 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE, 286 EV_ADD | EV_ENABLE | EV_CLEAR, 287 NOTE_DELETE | NOTE_RENAME, 0, 0); 288 n++; 289 } 290 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ, 291 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0); 292 n++; 293 } 294 295 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) { 296 action = USE_SLEEP; 297 } 298 } 299 300 /* 301 * follow -- display the file, from an offset, forward. 302 * 303 */ 304 void 305 follow(file_info_t *files, enum STYLE style, off_t off) 306 { 307 int active, ev_change, i, n; 308 struct stat sb2; 309 file_info_t *file; 310 FILE *ftmp; 311 struct timespec ts; 312 313 /* Position each of the files */ 314 active = 0; 315 for (i = 0, file = files; i < no_files; i++, file++) { 316 if (!file->fp) 317 continue; 318 active = 1; 319 if (vflag || (qflag == 0 && no_files > 1)) 320 printfn(file->file_name, 1); 321 forward(file->fp, file->file_name, style, off, &file->st); 322 } 323 if (!Fflag && !active) 324 return; 325 326 last = --file; 327 328 kq = kqueue(); 329 if (kq < 0) 330 err(1, "kqueue"); 331 /* 332 * The number of kqueue events we track may vary over time and may 333 * even grow past its initial value in the -F case, but it will 334 * never exceed two per file, so just preallocate that. 335 */ 336 ev = malloc(no_files * 2 * sizeof(struct kevent)); 337 if (ev == NULL) 338 err(1, "failed to allocate memory for kevents"); 339 set_events(files); 340 341 for (;;) { 342 ev_change = 0; 343 if (Fflag) { 344 for (i = 0, file = files; i < no_files; i++, file++) { 345 if (!file->fp) { 346 file->fp = 347 fileargs_fopen(fa, file->file_name, 348 "r"); 349 if (file->fp != NULL && 350 fstat(fileno(file->fp), &file->st) 351 == -1) { 352 fclose(file->fp); 353 file->fp = NULL; 354 } 355 if (file->fp != NULL) 356 ev_change++; 357 continue; 358 } 359 if (fileno(file->fp) == STDIN_FILENO) 360 continue; 361 ftmp = fileargs_fopen(fa, file->file_name, "r"); 362 if (ftmp == NULL || 363 fstat(fileno(ftmp), &sb2) == -1) { 364 if (errno != ENOENT) 365 ierr(file->file_name); 366 show(file); 367 if (file->fp != NULL) { 368 fclose(file->fp); 369 file->fp = NULL; 370 } 371 if (ftmp != NULL) { 372 fclose(ftmp); 373 } 374 ev_change++; 375 continue; 376 } 377 378 if (sb2.st_ino != file->st.st_ino || 379 sb2.st_dev != file->st.st_dev || 380 sb2.st_nlink == 0) { 381 show(file); 382 if (file->fp != NULL) 383 fclose(file->fp); 384 file->fp = ftmp; 385 memcpy(&file->st, &sb2, 386 sizeof(struct stat)); 387 ev_change++; 388 } else { 389 fclose(ftmp); 390 } 391 } 392 } 393 394 for (i = 0, file = files; i < no_files; i++, file++) 395 if (file->fp && !show(file)) 396 ev_change++; 397 398 if (ev_change) 399 set_events(files); 400 401 switch (action) { 402 case USE_KQUEUE: 403 ts.tv_sec = 1; 404 ts.tv_nsec = 0; 405 /* 406 * In the -F case we set a timeout to ensure that 407 * we re-stat the file at least once every second. 408 * If we've received EINTR, ignore it. Both reasons 409 * for its generation are transient. 410 */ 411 do { 412 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL); 413 if (n < 0 && errno != EINTR) 414 err(1, "kevent"); 415 } while (n < 0); 416 if (n == 0) { 417 /* timeout */ 418 break; 419 } else if (ev->filter == EVFILT_READ && ev->data < 0) { 420 /* file shrank, reposition to end */ 421 if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) { 422 ierr(file->file_name); 423 continue; 424 } 425 } 426 break; 427 428 case USE_SLEEP: 429 (void) usleep(250000); 430 break; 431 } 432 } 433 } 434