2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Edward Sze-Tyan Wang.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
37 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
42 static const char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93";
45 #include <sys/types.h>
49 #include <sys/event.h>
62 static void rlines(FILE *, off_t, struct stat *);
63 static void show(file_info_t *);
64 static void set_events(file_info_t *files);
66 /* defines for inner loop actions */
72 int action = USE_SLEEP;
76 * forward -- display the file, from an offset, forward.
78 * There are eight separate cases for this -- regular and non-regular
79 * files, by bytes or lines and from the beginning or end of the file.
81 * FBYTES byte offset from the beginning of the file
83 * NOREG read, counting bytes
85 * FLINES line offset from the beginning of the file
86 * REG read, counting lines
87 * NOREG read, counting lines
89 * RBYTES byte offset from the end of the file
91 * NOREG cyclically read characters into a wrap-around buffer
94 * REG mmap the file and step back until reach the correct offset.
95 * NOREG cyclically read lines into a wrap-around array of buffers
98 forward(FILE *fp, enum STYLE style, off_t off, struct stat *sbp)
106 if (S_ISREG(sbp->st_mode)) {
107 if (sbp->st_size < off)
109 if (fseeko(fp, off, SEEK_SET) == -1) {
114 if ((ch = getc(fp)) == EOF) {
126 if ((ch = getc(fp)) == EOF) {
133 if (ch == '\n' && !--off)
138 if (S_ISREG(sbp->st_mode)) {
139 if (sbp->st_size >= off &&
140 fseeko(fp, -off, SEEK_END) == -1) {
144 } else if (off == 0) {
145 while (getc(fp) != EOF);
155 if (S_ISREG(sbp->st_mode))
157 if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
162 rlines(fp, off, sbp);
164 while (getc(fp) != EOF);
177 while ((ch = getc(fp)) != EOF)
178 if (putchar(ch) == EOF)
184 (void)fflush(stdout);
188 * rlines -- display the last offset lines of the file.
200 if (!(size = sbp->st_size))
204 map.mapoff = map.maxoff = size;
207 * Last char is special, ignore whether newline or not. Note that
208 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
211 while (curoff >= 0) {
212 if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
216 for (i = curoff - map.mapoff; i >= 0; i--)
217 if (map.start[i] == '\n' && --off == 0)
219 /* `i' is either the map offset of a '\n', or -1. */
220 curoff = map.mapoff + i;
225 if (mapprint(&map, curoff, size - curoff) != 0) {
230 /* Set the file pointer to reflect the length displayed. */
231 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
235 if (map.start != NULL && munmap(map.start, map.maplen)) {
242 * follow -- display the file, from an offset, forward.
247 show(file_info_t *file)
250 static file_info_t *last;
252 while ((ch = getc(file->fp)) != EOF) {
253 if (last != file && no_files > 1) {
254 (void)printf("\n==> %s <==\n", file->file_name);
257 if (putchar(ch) == EOF)
260 (void)fflush(stdout);
261 if (ferror(file->fp)) {
269 set_events(file_info_t *files)
279 for (i = 0, file = files; i < no_files; i++, file++) {
282 if (Fflag && fileno(file->fp) != STDIN_FILENO) {
283 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE,
284 EV_ADD | EV_ENABLE | EV_CLEAR,
285 NOTE_DELETE | NOTE_RENAME, 0, 0);
288 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ,
289 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0);
293 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) {
299 follow(file_info_t *files, enum STYLE style, off_t off)
301 int active, i, n = -1;
306 /* Position each of the files */
311 for (i = 0; i < no_files; i++, file++) {
316 (void)printf("\n==> %s <==\n", file->file_name);
317 forward(file->fp, style, off, &file->st);
318 if (Fflag && fileno(file->fp) != STDIN_FILENO)
328 ev = malloc(n * sizeof(struct kevent));
330 err(1, "Couldn't allocate memory for kevents.");
334 for (i = 0, file = files; i < no_files; i++, file++) {
337 if (Fflag && file->fp && fileno(file->fp) != STDIN_FILENO) {
338 if (stat(file->file_name, &sb2) != 0) {
339 /* file was rotated, skip it until it reappears */
342 if (sb2.st_ino != file->st.st_ino ||
343 sb2.st_dev != file->st.st_dev ||
345 file->fp = freopen(file->file_name, "r", file->fp);
346 if (file->fp == NULL) {
350 memcpy(&file->st, &sb2, sizeof(struct stat));
363 * In the -F case we set a timeout to ensure that
364 * we re-stat the file at least once every second.
366 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL);
372 } else if (ev->filter == EVFILT_READ && ev->data < 0) {
373 /* file shrank, reposition to end */
374 if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) {
382 (void) usleep(250000);