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
forward(FILE * fp,const char * fn,enum STYLE style,off_t off,struct stat * sbp)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
rlines(FILE * fp,const char * fn,off_t off,struct stat * sbp)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
show(file_info_t * file)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
set_events(file_info_t * files)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
follow(file_info_t * files,enum STYLE style,off_t off)308 follow(file_info_t *files, enum STYLE style, off_t off)
309 {
310 int active, ev_change, i, n;
311 struct stat sb2;
312 file_info_t *file;
313 FILE *ftmp;
314 struct timespec ts;
315
316 /* Position each of the files */
317 active = 0;
318 for (i = 0, file = files; i < no_files; i++, file++) {
319 if (!file->fp)
320 continue;
321 active = 1;
322 if (vflag || (qflag == 0 && no_files > 1))
323 printfn(file->file_name, 1);
324 forward(file->fp, file->file_name, style, off, &file->st);
325 }
326 if (!Fflag && !active)
327 return;
328
329 last = --file;
330
331 kq = kqueue();
332 if (kq < 0)
333 err(1, "kqueue");
334 /*
335 * The number of kqueue events we track may vary over time and may
336 * even grow past its initial value in the -F case, but it will
337 * never exceed two per file, so just preallocate that.
338 */
339 ev = malloc(no_files * 2 * sizeof(struct kevent));
340 if (ev == NULL)
341 err(1, "failed to allocate memory for kevents");
342 set_events(files);
343
344 for (;;) {
345 ev_change = 0;
346 if (Fflag) {
347 for (i = 0, file = files; i < no_files; i++, file++) {
348 if (!file->fp) {
349 file->fp =
350 fileargs_fopen(fa, file->file_name,
351 "r");
352 if (file->fp != NULL &&
353 fstat(fileno(file->fp), &file->st)
354 == -1) {
355 fclose(file->fp);
356 file->fp = NULL;
357 }
358 if (file->fp != NULL)
359 ev_change++;
360 continue;
361 }
362 if (fileno(file->fp) == STDIN_FILENO)
363 continue;
364 ftmp = fileargs_fopen(fa, file->file_name, "r");
365 if (ftmp == NULL ||
366 fstat(fileno(ftmp), &sb2) == -1) {
367 if (errno != ENOENT)
368 ierr(file->file_name);
369 show(file);
370 if (file->fp != NULL) {
371 fclose(file->fp);
372 file->fp = NULL;
373 }
374 if (ftmp != NULL) {
375 fclose(ftmp);
376 }
377 ev_change++;
378 continue;
379 }
380
381 if (sb2.st_ino != file->st.st_ino ||
382 sb2.st_dev != file->st.st_dev ||
383 sb2.st_nlink == 0) {
384 show(file);
385 if (file->fp != NULL)
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 received 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 err(1, "kevent");
418 } while (n < 0);
419 if (n == 0) {
420 /* timeout */
421 break;
422 } else if (ev->filter == EVFILT_READ && ev->data < 0) {
423 /* file shrank, reposition to end */
424 if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) {
425 ierr(file->file_name);
426 continue;
427 }
428 }
429 break;
430
431 case USE_SLEEP:
432 (void) usleep(250000);
433 break;
434 }
435 }
436 }
437