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 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
38 static const char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93";
41 #include <sys/param.h>
42 #include <sys/mount.h>
43 #include <sys/types.h>
47 #include <sys/event.h>
60 static void rlines(FILE *, const char *fn, off_t, struct stat *);
61 static int show(file_info_t *);
62 static void set_events(file_info_t *files);
64 /* defines for inner loop actions */
70 int action = USE_SLEEP;
73 static const file_info_t *last;
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, const char *fn, 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);
151 if (bytes(fp, fn, off))
155 if (S_ISREG(sbp->st_mode))
157 if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
162 rlines(fp, fn, off, sbp);
164 while (getc(fp) != EOF);
170 if (lines(fp, fn, off))
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.
191 rlines(FILE *fp, const char *fn, off_t off, struct stat *sbp)
197 if (!(size = sbp->st_size))
201 map.mapoff = map.maxoff = size;
204 * Last char is special, ignore whether newline or not. Note that
205 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
208 while (curoff >= 0) {
209 if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
213 for (i = curoff - map.mapoff; i >= 0; i--)
214 if (map.start[i] == '\n' && --off == 0)
216 /* `i' is either the map offset of a '\n', or -1. */
217 curoff = map.mapoff + i;
222 if (mapprint(&map, curoff, size - curoff) != 0) {
227 /* Set the file pointer to reflect the length displayed. */
228 if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
232 if (map.start != NULL && munmap(map.start, map.maplen)) {
239 show(file_info_t *file)
243 while ((ch = getc(file->fp)) != EOF) {
244 if (last != file && no_files > 1) {
246 (void)printf("\n==> %s <==\n", file->file_name);
249 if (putchar(ch) == EOF)
252 (void)fflush(stdout);
253 if (ferror(file->fp)) {
256 ierr(file->file_name);
264 set_events(file_info_t *files)
275 for (i = 0, file = files; i < no_files; i++, file++) {
279 if (fstatfs(fileno(file->fp), &sf) == 0 &&
280 (sf.f_flags & MNT_LOCAL) == 0) {
285 if (Fflag && fileno(file->fp) != STDIN_FILENO) {
286 EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE,
287 EV_ADD | EV_ENABLE | EV_CLEAR,
288 NOTE_DELETE | NOTE_RENAME, 0, 0);
291 EV_SET(&ev[n], fileno(file->fp), EVFILT_READ,
292 EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0);
296 if (kevent(kq, ev, n, NULL, 0, &ts) < 0) {
302 * follow -- display the file, from an offset, forward.
306 follow(file_info_t *files, enum STYLE style, off_t off)
308 int active, ev_change, i, n = -1;
313 /* Position each of the files */
318 for (i = 0; i < no_files; i++, file++) {
322 if (no_files > 1 && !qflag)
323 (void)printf("\n==> %s <==\n", file->file_name);
324 forward(file->fp, file->file_name, style, off, &file->st);
325 if (Fflag && fileno(file->fp) != STDIN_FILENO)
329 if (!Fflag && !active)
337 ev = malloc(n * sizeof(struct kevent));
339 err(1, "Couldn't allocate memory for kevents.");
345 for (i = 0, file = files; i < no_files; i++, file++) {
347 file->fp = fopen(file->file_name, "r");
348 if (file->fp != NULL &&
349 fstat(fileno(file->fp), &file->st)
354 if (file->fp != NULL)
358 if (fileno(file->fp) == STDIN_FILENO)
360 if (stat(file->file_name, &sb2) == -1) {
362 ierr(file->file_name);
364 if (file->fp != NULL) {
372 if (sb2.st_ino != file->st.st_ino ||
373 sb2.st_dev != file->st.st_dev ||
376 file->fp = freopen(file->file_name, "r",
378 if (file->fp != NULL)
379 memcpy(&file->st, &sb2,
380 sizeof(struct stat));
381 else if (errno != ENOENT)
382 ierr(file->file_name);
388 for (i = 0, file = files; i < no_files; i++, file++)
389 if (file->fp && !show(file))
400 * In the -F case we set a timeout to ensure that
401 * we re-stat the file at least once every second.
403 n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL);
409 } else if (ev->filter == EVFILT_READ && ev->data < 0) {
410 /* file shrank, reposition to end */
411 if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) {
412 ierr(file->file_name);
419 (void) usleep(250000);