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
39 static char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93";
41 static const char rcsid[] =
42 "$FreeBSD: src/usr.bin/tail/forward.c,v 1.11.6.7 2003/01/07 05:26:22 tjr Exp $";
45 #include <sys/types.h>
49 #include <sys/event.h>
61 static void rlines __P((FILE *, off_t, struct stat *));
63 /* defines for inner loop actions */
69 * forward -- display the file, from an offset, forward.
71 * There are eight separate cases for this -- regular and non-regular
72 * files, by bytes or lines and from the beginning or end of the file.
74 * FBYTES byte offset from the beginning of the file
76 * NOREG read, counting bytes
78 * FLINES line offset from the beginning of the file
79 * REG read, counting lines
80 * NOREG read, counting lines
82 * RBYTES byte offset from the end of the file
84 * NOREG cyclically read characters into a wrap-around buffer
87 * REG mmap the file and step back until reach the correct offset.
88 * NOREG cyclically read lines into a wrap-around array of buffers
91 forward(fp, style, off, sbp)
98 int action = USE_SLEEP;
107 if (S_ISREG(sbp->st_mode)) {
108 if (sbp->st_size < off)
110 if (fseeko(fp, off, SEEK_SET) == -1) {
115 if ((ch = getc(fp)) == EOF) {
127 if ((ch = getc(fp)) == EOF) {
134 if (ch == '\n' && !--off)
139 if (S_ISREG(sbp->st_mode)) {
140 if (sbp->st_size >= off &&
141 fseeko(fp, -off, SEEK_END) == -1) {
145 } else if (off == 0) {
146 while (getc(fp) != EOF);
156 if (S_ISREG(sbp->st_mode))
158 if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
163 rlines(fp, off, sbp);
165 while (getc(fp) != EOF);
184 while ((ch = getc(fp)) != EOF)
185 if (putchar(ch) == EOF)
191 (void)fflush(stdout);
202 if (Fflag && fileno(fp) != STDIN_FILENO) {
203 EV_SET(&ev[n], fileno(fp), EVFILT_VNODE,
204 EV_ADD | EV_ENABLE | EV_CLEAR,
205 NOTE_DELETE | NOTE_RENAME, 0, 0);
208 EV_SET(&ev[n], fileno(fp), EVFILT_READ,
209 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0);
212 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) {
223 * In the -F case we set a timeout to ensure that
224 * we re-stat the file at least once every second.
226 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL);
232 } else if (ev->filter == EVFILT_READ && ev->data < 0) {
233 /* file shrank, reposition to end */
234 if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
242 (void) usleep(250000);
247 if (Fflag && fileno(fp) != STDIN_FILENO) {
248 while (stat(fname, &sb2) != 0)
249 /* file was rotated, wait until it reappears */
251 if (sb2.st_ino != sbp->st_ino ||
252 sb2.st_dev != sbp->st_dev ||
253 sb2.st_rdev != sbp->st_rdev ||
255 fp = freopen(fname, "r", fp);
269 * rlines -- display the last offset lines of the file.
281 if (!(size = sbp->st_size))
285 map.mapoff = map.maxoff = size;
288 * Last char is special, ignore whether newline or not. Note that
289 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
292 while (curoff >= 0) {
293 if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
297 for (i = curoff - map.mapoff; i >= 0; i--)
298 if (map.start[i] == '\n' && --off == 0)
300 /* `i' is either the map offset of a '\n', or -1. */
301 curoff = map.mapoff + i;
306 if (mapprint(&map, curoff, size - curoff) != 0) {
311 /* Set the file pointer to reflect the length displayed. */
312 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
316 if (map.start != NULL && munmap(map.start, map.maplen)) {