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
36 * @(#)forward.c 8.1 (Berkeley) 6/6/93
37 * $FreeBSD: src/usr.bin/tail/forward.c,v 1.11.6.7 2003/01/07 05:26:22 tjr Exp $
38 * $DragonFly: src/usr.bin/tail/forward.c,v 1.6 2005/03/01 21:37:33 cpressey Exp $
41 #include <sys/types.h>
45 #include <sys/event.h>
57 static void rlines(FILE *, off_t, struct stat *);
59 /* defines for inner loop actions */
65 int action = USE_SLEEP;
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(FILE *fp, enum STYLE style, off_t off, struct stat *sbp)
99 if (S_ISREG(sbp->st_mode)) {
100 if (sbp->st_size < off)
102 if (fseeko(fp, off, SEEK_SET) == -1) {
107 if ((ch = getc(fp)) == EOF) {
119 if ((ch = getc(fp)) == EOF) {
126 if (ch == '\n' && !--off)
131 if (S_ISREG(sbp->st_mode)) {
132 if (sbp->st_size >= off &&
133 fseeko(fp, -off, SEEK_END) == -1) {
137 } else if (off == 0) {
138 while (getc(fp) != EOF);
144 if (display_bytes(fp, off))
148 if (S_ISREG(sbp->st_mode))
150 if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
155 rlines(fp, off, sbp);
157 while (getc(fp) != EOF);
163 if (display_lines(fp, off))
167 errx(1, "internal error: forward style cannot be REVERSE");
171 while ((ch = getc(fp)) != EOF) {
172 if (putchar(ch) == EOF)
183 * rlines -- display the last offset lines of the file.
186 rlines(FILE *fp, off_t off, struct stat *sbp)
192 if (!(size = sbp->st_size))
196 map.mapoff = map.maxoff = size;
199 * Last char is special, ignore whether newline or not. Note that
200 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
203 while (curoff >= 0) {
204 if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
208 for (i = curoff - map.mapoff; i >= 0; i--)
209 if (map.start[i] == '\n' && --off == 0)
211 /* `i' is either the map offset of a '\n', or -1. */
212 curoff = map.mapoff + i;
217 if (mapprint(&map, curoff, size - curoff) != 0) {
222 /* Set the file pointer to reflect the length displayed. */
223 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
227 if (map.start != NULL && munmap(map.start, map.maplen)) {
234 * follow -- display the file, from an offset, forward.
238 show(file_info_t *file, int at_index)
243 while ((ch = getc(file->fp)) != EOF) {
244 if (first && no_files > 1) {
245 showfilename(at_index, file->file_name);
248 if (putchar(ch) == EOF)
252 if (ferror(file->fp)) {
261 showfilename(int at_index, const char *filename)
263 static int last_index = -1;
264 static int continuing = 0;
266 if (last_index == at_index)
270 printf("==> %s <==\n", filename);
272 last_index = at_index;
276 set_events(file_info_t *files)
287 for (i = 0, file = files; i < no_files; i++, file++) {
288 if (file->fp == NULL)
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);
296 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ,
297 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0);
301 if (kevent(kq, ev, n, NULL, 0, &ts) < 0)
306 follow(file_info_t *files, enum STYLE style, off_t off)
316 /* Position each of the files */
320 for (i = 0; i < no_files; i++, file++) {
325 showfilename(i, file->file_name);
326 forward(file->fp, style, off, &file->st);
327 if (Fflag && fileno(file->fp) != STDIN_FILENO)
338 ev = malloc(n * sizeof(struct kevent));
340 err(1, "Couldn't allocate memory for kevents.");
344 for (i = 0, file = files; i < no_files; i++, file++) {
345 if (file->fp == NULL)
347 if (Fflag && fileno(file->fp) != STDIN_FILENO) {
348 if (stat(file->file_name, &sb2) == -1) {
350 * file was rotated, skip it until it
355 if (sb2.st_ino != file->st.st_ino ||
356 sb2.st_dev != file->st.st_dev ||
358 file->fp = freopen(file->file_name, "r",
360 if (file->fp == NULL) {
364 memcpy(&file->st, &sb2,
365 sizeof(struct stat));
378 * In the -F case, we set a timeout to ensure that
379 * we re-stat the file at least once every second.
381 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL);
387 } else if (ev->filter == EVFILT_READ && ev->data < 0) {
388 /* file shrank, reposition to end */
389 if (lseek(ev->ident, 0, SEEK_END) == -1) {