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
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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 * @(#)read.c 8.1 (Berkeley) 6/6/93
37 * $FreeBSD: src/usr.bin/tail/read.c,v 1.6.8.1 2001/01/24 08:41:14 ru Exp $
38 * $DragonFly: src/usr.bin/tail/read.c,v 1.6 2008/02/05 14:35:43 matthias Exp $
41 #include <sys/types.h>
53 * display_bytes -- read bytes to an offset from the end and display.
55 * This is the function that reads to a byte offset from the end of the input,
56 * storing the data in a wrap-around buffer which is then displayed. If the
57 * rflag is set, the data is displayed in lines in reverse order, and this
58 * routine has the usual nastiness of trying to find the newlines. Otherwise,
59 * it is displayed from the character closest to the beginning of the input to
63 display_bytes(FILE *fp, off_t off)
70 if ((sp = p = malloc(off)) == NULL)
73 for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) {
87 for (t = p - 1, len = 0; t >= sp; --t, ++len)
88 if (*t == '\n' && len) {
94 for (t = ep - 1, len = 0; t >= p; --t, ++len)
111 if (wrap && (len = ep - p))
113 if ((len = p - sp) != 0)
121 * display_lines -- read lines to an offset from the end and display.
123 * This is the function that reads to a line offset from the end of the input,
124 * storing the data in an array of buffers which is then displayed. If the
125 * rflag is set, the data is displayed in lines in reverse order, and this
126 * routine has the usual nastiness of trying to find the newlines. Otherwise,
127 * it is displayed from the line closest to the beginning of the input to
131 display_lines(FILE *fp, off_t off)
140 int blen, cnt, recno, wrap;
143 if ((lines = malloc(off * sizeof(*lines))) == NULL)
145 bzero(lines, off * sizeof(*lines));
147 blen = cnt = recno = wrap = 0;
149 while ((ch = getc(fp)) != EOF) {
151 if ((sp = realloc(sp, blen += 1024)) == NULL)
157 if (lines[recno].blen < cnt) {
158 lines[recno].blen = cnt + 256;
159 if ((lines[recno].l = realloc(lines[recno].l,
160 lines[recno].blen)) == NULL)
163 bcopy(sp, lines[recno].l, lines[recno].len = cnt);
166 if (++recno == off) {
180 lines[recno].len = cnt;
181 if (++recno == off) {
188 for (cnt = recno - 1; cnt >= 0; --cnt)
189 WR(lines[cnt].l, lines[cnt].len);
191 for (cnt = off - 1; cnt >= recno; --cnt)
192 WR(lines[cnt].l, lines[cnt].len);
195 for (cnt = recno; cnt < off; ++cnt)
196 WR(lines[cnt].l, lines[cnt].len);
197 for (cnt = 0; cnt < recno; ++cnt)
198 WR(lines[cnt].l, lines[cnt].len);
201 for (cnt = 0; cnt < off; cnt++)