1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Edward Sze-Tyan Wang.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
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. 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.
19 *
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
30 * SUCH DAMAGE.
31 *
32 * @(#)read.c 8.1 (Berkeley) 6/6/93
33 * $FreeBSD: src/usr.bin/tail/read.c,v 1.6.8.1 2001/01/24 08:41:14 ru Exp $
34 * $DragonFly: src/usr.bin/tail/read.c,v 1.6 2008/02/05 14:35:43 matthias Exp $
35 */
36
37 #include <sys/types.h>
38 #include <sys/stat.h>
39 #include <fcntl.h>
40 #include <errno.h>
41 #include <unistd.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <err.h>
46 #include "extern.h"
47
48 /*
49 * display_bytes -- read bytes to an offset from the end and display.
50 *
51 * This is the function that reads to a byte offset from the end of the input,
52 * storing the data in a wrap-around buffer which is then displayed. If the
53 * rflag is set, the data is displayed in lines in reverse order, and this
54 * routine has the usual nastiness of trying to find the newlines. Otherwise,
55 * it is displayed from the character closest to the beginning of the input to
56 * the end.
57 */
58 int
display_bytes(FILE * fp,off_t off)59 display_bytes(FILE *fp, off_t off)
60 {
61 int ch, len, tlen;
62 char *ep, *p, *t;
63 int wrap;
64 char *sp;
65
66 if ((sp = p = malloc(off)) == NULL)
67 err(1, "malloc");
68
69 for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) {
70 *p = ch;
71 if (++p == ep) {
72 wrap = 1;
73 p = sp;
74 }
75 }
76 if (ferror(fp)) {
77 ierr();
78 free(sp);
79 return 1;
80 }
81
82 if (rflag) {
83 for (t = p - 1, len = 0; t >= sp; --t, ++len)
84 if (*t == '\n' && len) {
85 WR(t + 1, len);
86 len = 0;
87 }
88 if (wrap) {
89 tlen = len;
90 for (t = ep - 1, len = 0; t >= p; --t, ++len)
91 if (*t == '\n') {
92 if (len) {
93 WR(t + 1, len);
94 len = 0;
95 }
96 if (tlen) {
97 WR(sp, tlen);
98 tlen = 0;
99 }
100 }
101 if (len)
102 WR(t + 1, len);
103 if (tlen)
104 WR(sp, tlen);
105 }
106 } else {
107 if (wrap && (len = ep - p))
108 WR(p, len);
109 if ((len = p - sp) != 0)
110 WR(sp, len);
111 }
112 free(sp);
113 return 0;
114 }
115
116 /*
117 * display_lines -- read lines to an offset from the end and display.
118 *
119 * This is the function that reads to a line offset from the end of the input,
120 * storing the data in an array of buffers which is then displayed. If the
121 * rflag is set, the data is displayed in lines in reverse order, and this
122 * routine has the usual nastiness of trying to find the newlines. Otherwise,
123 * it is displayed from the line closest to the beginning of the input to
124 * the end.
125 */
126 int
display_lines(FILE * fp,off_t off)127 display_lines(FILE *fp, off_t off)
128 {
129 struct {
130 ssize_t blen;
131 ssize_t len;
132 char *l;
133 } *lines;
134 int ch, rc = 0;
135 char *p = NULL;
136 int blen, cnt, recno, wrap;
137 char *sp;
138
139 if ((lines = malloc(off * sizeof(*lines))) == NULL)
140 err(1, "malloc");
141 bzero(lines, off * sizeof(*lines));
142 sp = NULL;
143 blen = cnt = recno = wrap = 0;
144
145 while ((ch = getc(fp)) != EOF) {
146 if (++cnt > blen) {
147 if ((sp = realloc(sp, blen += 1024)) == NULL)
148 err(1, "realloc");
149 p = sp + cnt - 1;
150 }
151 *p++ = ch;
152 if (ch == '\n') {
153 if (lines[recno].blen < cnt) {
154 lines[recno].blen = cnt + 256;
155 if ((lines[recno].l = realloc(lines[recno].l,
156 lines[recno].blen)) == NULL)
157 err(1, "realloc");
158 }
159 bcopy(sp, lines[recno].l, lines[recno].len = cnt);
160 cnt = 0;
161 p = sp;
162 if (++recno == off) {
163 wrap = 1;
164 recno = 0;
165 }
166 }
167 }
168 if (ferror(fp)) {
169 ierr();
170 rc = 1;
171 goto out;
172 }
173 if (cnt) {
174 lines[recno].l = sp;
175 sp = NULL;
176 lines[recno].len = cnt;
177 if (++recno == off) {
178 wrap = 1;
179 recno = 0;
180 }
181 }
182
183 if (rflag) {
184 for (cnt = recno - 1; cnt >= 0; --cnt)
185 WR(lines[cnt].l, lines[cnt].len);
186 if (wrap)
187 for (cnt = off - 1; cnt >= recno; --cnt)
188 WR(lines[cnt].l, lines[cnt].len);
189 } else {
190 if (wrap)
191 for (cnt = recno; cnt < off; ++cnt)
192 WR(lines[cnt].l, lines[cnt].len);
193 for (cnt = 0; cnt < recno; ++cnt)
194 WR(lines[cnt].l, lines[cnt].len);
195 }
196 out:
197 for (cnt = 0; cnt < off; cnt++)
198 free(lines[cnt].l);
199 free(sp);
200 free(lines);
201 return (rc);
202 }
203