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 #ifndef lint 37 static const char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93"; 38 #endif 39 40 #include <sys/param.h> 41 #include <sys/mount.h> 42 #include <sys/types.h> 43 #include <sys/stat.h> 44 #include <sys/time.h> 45 #include <sys/mman.h> 46 #include <sys/event.h> 47 48 #include <err.h> 49 #include <errno.h> 50 #include <fcntl.h> 51 #include <limits.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 #include <unistd.h> 56 57 #include <libcasper.h> 58 #include <casper/cap_fileargs.h> 59 60 #include "extern.h" 61 62 static void rlines(FILE *, const char *fn, off_t, struct stat *); 63 static int show(file_info_t *); 64 static void set_events(file_info_t *files); 65 66 /* defines for inner loop actions */ 67 #define USE_SLEEP 0 68 #define USE_KQUEUE 1 69 #define ADD_EVENTS 2 70 71 static struct kevent *ev; 72 static int action = USE_SLEEP; 73 static int kq; 74 75 static const file_info_t *last; 76 77 /* 78 * forward -- display the file, from an offset, forward. 79 * 80 * There are eight separate cases for this -- regular and non-regular 81 * files, by bytes or lines and from the beginning or end of the file. 82 * 83 * FBYTES byte offset from the beginning of the file 84 * REG seek 85 * NOREG read, counting bytes 86 * 87 * FLINES line offset from the beginning of the file 88 * REG read, counting lines 89 * NOREG read, counting lines 90 * 91 * RBYTES byte offset from the end of the file 92 * REG seek 93 * NOREG cyclically read characters into a wrap-around buffer 94 * 95 * RLINES 96 * REG mmap the file and step back until reach the correct offset. 97 * NOREG cyclically read lines into a wrap-around array of buffers 98 */ 99 void 100 forward(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 101 { 102 int ch; 103 104 switch(style) { 105 case FBYTES: 106 if (off == 0) 107 break; 108 if (S_ISREG(sbp->st_mode)) { 109 if (sbp->st_size < off) 110 off = sbp->st_size; 111 if (fseeko(fp, off, SEEK_SET) == -1) { 112 ierr(fn); 113 return; 114 } 115 } else while (off--) 116 if ((ch = getc(fp)) == EOF) { 117 if (ferror(fp)) { 118 ierr(fn); 119 return; 120 } 121 break; 122 } 123 break; 124 case FLINES: 125 if (off == 0) 126 break; 127 for (;;) { 128 if ((ch = getc(fp)) == EOF) { 129 if (ferror(fp)) { 130 ierr(fn); 131 return; 132 } 133 break; 134 } 135 if (ch == '\n' && !--off) 136 break; 137 } 138 break; 139 case RBYTES: 140 if (S_ISREG(sbp->st_mode)) { 141 if (sbp->st_size >= off && 142 fseeko(fp, -off, SEEK_END) == -1) { 143 ierr(fn); 144 return; 145 } 146 } else if (off == 0) { 147 while (getc(fp) != EOF); 148 if (ferror(fp)) { 149 ierr(fn); 150 return; 151 } 152 } else 153 if (bytes(fp, fn, off)) 154 return; 155 break; 156 case RLINES: 157 if (S_ISREG(sbp->st_mode)) 158 if (!off) { 159 if (fseeko(fp, (off_t)0, SEEK_END) == -1) { 160 ierr(fn); 161 return; 162 } 163 } else 164 rlines(fp, fn, off, sbp); 165 else if (off == 0) { 166 while (getc(fp) != EOF); 167 if (ferror(fp)) { 168 ierr(fn); 169 return; 170 } 171 } else 172 if (lines(fp, fn, off)) 173 return; 174 break; 175 default: 176 break; 177 } 178 179 while ((ch = getc(fp)) != EOF) 180 if (putchar(ch) == EOF) 181 oerr(); 182 if (ferror(fp)) { 183 ierr(fn); 184 return; 185 } 186 (void)fflush(stdout); 187 } 188 189 /* 190 * rlines -- display the last offset lines of the file. 191 */ 192 static void 193 rlines(FILE *fp, const char *fn, off_t off, struct stat *sbp) 194 { 195 struct mapinfo map; 196 off_t curoff, size; 197 int i; 198 199 if (!(size = sbp->st_size)) 200 return; 201 map.start = NULL; 202 map.fd = fileno(fp); 203 map.mapoff = map.maxoff = size; 204 205 /* 206 * Last char is special, ignore whether newline or not. Note that 207 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 208 */ 209 curoff = size - 2; 210 while (curoff >= 0) { 211 if (curoff < map.mapoff && maparound(&map, curoff) != 0) { 212 ierr(fn); 213 return; 214 } 215 for (i = curoff - map.mapoff; i >= 0; i--) 216 if (map.start[i] == '\n' && --off == 0) 217 break; 218 /* `i' is either the map offset of a '\n', or -1. */ 219 curoff = map.mapoff + i; 220 if (i >= 0) 221 break; 222 } 223 curoff++; 224 if (mapprint(&map, curoff, size - curoff) != 0) { 225 ierr(fn); 226 exit(1); 227 } 228 229 /* Set the file pointer to reflect the length displayed. */ 230 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) { 231 ierr(fn); 232 return; 233 } 234 if (map.start != NULL && munmap(map.start, map.maplen)) { 235 ierr(fn); 236 return; 237 } 238 } 239 240 static int 241 show(file_info_t *file) 242 { 243 int ch; 244 245 while ((ch = getc(file->fp)) != EOF) { 246 if (last != file) { 247 if (vflag || (qflag == 0 && no_files > 1)) 248 printfn(file->file_name, 1); 249 last = file; 250 } 251 if (putchar(ch) == EOF) 252 oerr(); 253 } 254 (void)fflush(stdout); 255 if (ferror(file->fp)) { 256 fclose(file->fp); 257 file->fp = NULL; 258 ierr(file->file_name); 259 return 0; 260 } 261 clearerr(file->fp); 262 return 1; 263 } 264 265 static void 266 set_events(file_info_t *files) 267 { 268 int i, n = 0; 269 file_info_t *file; 270 struct timespec ts; 271 struct statfs sf; 272 273 ts.tv_sec = 0; 274 ts.tv_nsec = 0; 275 276 action = USE_KQUEUE; 277 for (i = 0, file = files; i < no_files; i++, file++) { 278 if (! file->fp) 279 continue; 280 281 if (fstatfs(fileno(file->fp), &sf) == 0 && 282 (sf.f_flags & MNT_LOCAL) == 0) { 283 action = USE_SLEEP; 284 return; 285 } 286 287 if (Fflag && fileno(file->fp) != STDIN_FILENO) { 288 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE, 289 EV_ADD | EV_ENABLE | EV_CLEAR, 290 NOTE_DELETE | NOTE_RENAME, 0, 0); 291 n++; 292 } 293 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ, 294 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0); 295 n++; 296 } 297 298 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) { 299 action = USE_SLEEP; 300 } 301 } 302 303 /* 304 * follow -- display the file, from an offset, forward. 305 * 306 */ 307 void 308 follow(file_info_t *files, enum STYLE style, off_t off) 309 { 310 int active, ev_change, i, n = -1; 311 struct stat sb2; 312 file_info_t *file; 313 FILE *ftmp; 314 struct timespec ts; 315 316 /* Position each of the files */ 317 318 file = files; 319 active = 0; 320 n = 0; 321 for (i = 0; i < no_files; i++, file++) { 322 if (file->fp) { 323 active = 1; 324 n++; 325 if (vflag || (qflag == 0 && no_files > 1)) 326 printfn(file->file_name, 1); 327 forward(file->fp, file->file_name, style, off, &file->st); 328 if (Fflag && fileno(file->fp) != STDIN_FILENO) 329 n++; 330 } 331 } 332 if (!Fflag && !active) 333 return; 334 335 last = --file; 336 337 kq = kqueue(); 338 if (kq < 0) 339 err(1, "kqueue"); 340 ev = malloc(n * sizeof(struct kevent)); 341 if (! ev) 342 err(1, "Couldn't allocate memory for kevents."); 343 set_events(files); 344 345 for (;;) { 346 ev_change = 0; 347 if (Fflag) { 348 for (i = 0, file = files; i < no_files; i++, file++) { 349 if (!file->fp) { 350 file->fp = 351 fileargs_fopen(fa, file->file_name, 352 "r"); 353 if (file->fp != NULL && 354 fstat(fileno(file->fp), &file->st) 355 == -1) { 356 fclose(file->fp); 357 file->fp = NULL; 358 } 359 if (file->fp != NULL) 360 ev_change++; 361 continue; 362 } 363 if (fileno(file->fp) == STDIN_FILENO) 364 continue; 365 ftmp = fileargs_fopen(fa, file->file_name, "r"); 366 if (ftmp == NULL || 367 fstat(fileno(ftmp), &sb2) == -1) { 368 if (errno != ENOENT) 369 ierr(file->file_name); 370 show(file); 371 if (file->fp != NULL) { 372 fclose(file->fp); 373 file->fp = NULL; 374 } 375 if (ftmp != NULL) { 376 fclose(ftmp); 377 } 378 ev_change++; 379 continue; 380 } 381 382 if (sb2.st_ino != file->st.st_ino || 383 sb2.st_dev != file->st.st_dev || 384 sb2.st_nlink == 0) { 385 show(file); 386 fclose(file->fp); 387 file->fp = ftmp; 388 memcpy(&file->st, &sb2, 389 sizeof(struct stat)); 390 ev_change++; 391 } else { 392 fclose(ftmp); 393 } 394 } 395 } 396 397 for (i = 0, file = files; i < no_files; i++, file++) 398 if (file->fp && !show(file)) 399 ev_change++; 400 401 if (ev_change) 402 set_events(files); 403 404 switch (action) { 405 case USE_KQUEUE: 406 ts.tv_sec = 1; 407 ts.tv_nsec = 0; 408 /* 409 * In the -F case we set a timeout to ensure that 410 * we re-stat the file at least once every second. 411 * If we've recieved EINTR, ignore it. Both reasons 412 * for its generation are transient. 413 */ 414 do { 415 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL); 416 if (n < 0 && errno == EINTR) 417 continue; 418 if (n < 0) 419 err(1, "kevent"); 420 } while (n < 0); 421 if (n == 0) { 422 /* timeout */ 423 break; 424 } else if (ev->filter == EVFILT_READ && ev->data < 0) { 425 /* file shrank, reposition to end */ 426 if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) { 427 ierr(file->file_name); 428 continue; 429 } 430 } 431 break; 432 433 case USE_SLEEP: 434 (void) usleep(250000); 435 break; 436 } 437 } 438 } 439