1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
|
/* $OpenBSD: forward.c,v 1.20 2004/03/12 19:40:05 otto Exp $ */
/* $NetBSD: forward.c,v 1.7 1996/02/13 16:49:10 ghudson Exp $ */
/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Edward Sze-Tyan Wang.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93";
#endif
static char rcsid[] = "$OpenBSD: forward.c,v 1.20 2004/03/12 19:40:05 otto Exp $";
#endif /* not lint */
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/event.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
static int rlines(FILE *, off_t, struct stat *);
/*
* forward -- display the file, from an offset, forward.
*
* There are eight separate cases for this -- regular and non-regular
* files, by bytes or lines and from the beginning or end of the file.
*
* FBYTES byte offset from the beginning of the file
* REG seek
* NOREG read, counting bytes
*
* FLINES line offset from the beginning of the file
* REG read, counting lines
* NOREG read, counting lines
*
* RBYTES byte offset from the end of the file
* REG seek
* NOREG cyclically read characters into a wrap-around buffer
*
* RLINES
* REG step back until the correct offset is reached.
* NOREG cyclically read lines into a wrap-around array of buffers
*/
void
forward(fp, style, off, sbp)
FILE *fp;
enum STYLE style;
off_t off;
struct stat *sbp;
{
int ch;
struct stat nsb;
int kq, queue;
struct kevent ke;
switch(style) {
case FBYTES:
if (off == 0)
break;
if (S_ISREG(sbp->st_mode)) {
if (sbp->st_size < off)
off = sbp->st_size;
if (fseeko(fp, off, SEEK_SET) == -1) {
ierr();
return;
}
} else while (off--)
if ((ch = getc(fp)) == EOF) {
if (ferror(fp)) {
ierr();
return;
}
break;
}
break;
case FLINES:
if (off == 0)
break;
for (;;) {
if ((ch = getc(fp)) == EOF) {
if (ferror(fp)) {
ierr();
return;
}
break;
}
if (ch == '\n' && !--off)
break;
}
break;
case RBYTES:
if (S_ISREG(sbp->st_mode)) {
if (sbp->st_size >= off &&
fseeko(fp, -off, SEEK_END) == -1) {
ierr();
return;
}
} else if (off == 0) {
while (getc(fp) != EOF)
;
if (ferror(fp)) {
ierr();
return;
}
} else {
if (bytes(fp, off))
return;
}
break;
case RLINES:
if (S_ISREG(sbp->st_mode)) {
if (!off) {
if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
ierr();
return;
}
} else if (rlines(fp, off, sbp) != 0)
lines(fp, off);
} else if (off == 0) {
while (getc(fp) != EOF)
;
if (ferror(fp)) {
ierr();
return;
}
} else {
if (lines(fp, off))
return;
}
break;
}
kq = -1;
kq_retry:
if (fflag && ((kq = kqueue()) >= 0)) {
ke.ident = fileno(fp);
ke.flags = EV_ENABLE|EV_ADD|EV_CLEAR;
ke.filter = EVFILT_READ;
ke.fflags = ke.data = 0;
ke.udata = NULL;
if (kevent(kq, &ke, 1, NULL, 0, NULL) < 0) {
close(kq);
kq = -1;
} else if (S_ISREG(sbp->st_mode)) {
ke.ident = fileno(fp);
ke.flags = EV_ENABLE|EV_ADD|EV_CLEAR;
ke.filter = EVFILT_VNODE;
ke.fflags = NOTE_DELETE | NOTE_RENAME | NOTE_TRUNCATE;
if (kevent(kq, &ke, 1, NULL, 0, NULL) < 0) {
close(kq);
kq = -1;
}
}
}
for (;;) {
while (!feof(fp) && (ch = getc(fp)) != EOF)
if (putchar(ch) == EOF)
oerr();
if (ferror(fp)) {
ierr();
if (kq != -1)
close(kq);
return;
}
(void)fflush(stdout);
if (!fflag)
break;
clearerr(fp);
queue = 1;
if (kq < 0 || kevent(kq, NULL, 0, &ke, 1, NULL) <= 0) {
queue = 0;
sleep(1);
} else if (ke.filter == EVFILT_READ) {
continue;
} else if ((ke.fflags & NOTE_TRUNCATE) == 0) {
/*
* File was renamed or deleted.
*
* Continue to look at it until a new file reappears
* with the same name.
* Fall back to the old algorithm for that.
*/
close(kq);
kq = -1;
}
if (is_stdin || stat(fname, &nsb) != 0)
continue;
/* Reopen file if the inode changes or file was truncated */
if (nsb.st_ino != sbp->st_ino) {
warnx("%s has been replaced, reopening.", fname);
if ((fp = freopen(fname, "r", fp)) == NULL) {
ierr();
if (kq >= 0)
close(kq);
return;
}
(void)memcpy(sbp, &nsb, sizeof(nsb));
goto kq_retry;
} else if ((queue && (ke.fflags & NOTE_TRUNCATE)) ||
(!queue && nsb.st_size < sbp->st_size)) {
warnx("%s has been truncated, resetting.", fname);
fpurge(fp);
rewind(fp);
}
(void)memcpy(sbp, &nsb, sizeof(nsb));
}
if (kq >= 0)
close(kq);
}
/*
* rlines -- display the last offset lines of the file.
*/
static int
rlines(FILE *fp, off_t off, struct stat *sbp)
{
off_t pos;
int ch;
pos = sbp->st_size;
if (pos == 0)
return (0);
/*
* Position before char.
* Last char is special, ignore it whether newline or not.
*/
pos -= 2;
ch = EOF;
for (; off > 0 && pos >= 0; pos--) {
/* A seek per char isn't a problem with a smart stdio */
if (fseeko(fp, pos, SEEK_SET) == -1) {
ierr();
return (1);
}
if ((ch = getc(fp)) == '\n')
off--;
else if (ch == EOF) {
if (ferror(fp)) {
ierr();
return (1);
}
break;
}
}
/* If we read until start of file, put back last read char */
if (pos < 0 && off > 0 && ch != EOF && ungetc(ch, fp) == EOF) {
ierr();
return (1);
}
while (!feof(fp) && (ch = getc(fp)) != EOF)
if (putchar(ch) == EOF)
oerr();
if (ferror(fp)) {
ierr();
return (1);
}
return (0);
}
|