1 /* $NetBSD: read.c,v 1.17 2011/09/03 10:59:10 christos Exp $ */
2
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 #include <sys/cdefs.h>
36 #ifndef lint
37 #if 0
38 static char sccsid[] = "@(#)read.c 8.1 (Berkeley) 6/6/93";
39 #endif
40 __RCSID("$NetBSD: read.c,v 1.17 2011/09/03 10:59:10 christos Exp $");
41 #endif /* not lint */
42
43 #include <sys/types.h>
44 #include <sys/stat.h>
45 #include <fcntl.h>
46 #include <errno.h>
47 #include <unistd.h>
48 #include <stdio.h>
49 #include <stdlib.h>
50 #include <string.h>
51 #include "extern.h"
52
53 /*
54 * displaybytes -- read bytes to an offset from the end and display.
55 *
56 * This is the function that reads to a byte offset from the end of the input,
57 * storing the data in a wrap-around buffer which is then displayed. If the
58 * rflag is set, the data is displayed in lines in reverse order, and this
59 * routine has the usual nastiness of trying to find the newlines. Otherwise,
60 * it is displayed from the character closest to the beginning of the input to
61 * the end.
62 *
63 * Non-zero return means than a (non-fatal) error occurred.
64 */
65 int
displaybytes(FILE * fp,off_t off)66 displaybytes(FILE *fp, off_t off)
67 {
68 int ch, len, tlen;
69 char *ep, *p, *t;
70 int wrap;
71 char *sp;
72
73 if ((sp = p = malloc(off)) == NULL)
74 xerr(1, "malloc");
75
76 for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) {
77 *p = ch;
78 if (++p == ep) {
79 wrap = 1;
80 p = sp;
81 }
82 }
83 if (ferror(fp)) {
84 ierr();
85 return 1;
86 }
87
88 if (rflag) {
89 for (t = p - 1, len = 0; t >= sp; --t, ++len)
90 if (*t == '\n' && len) {
91 WR(t + 1, len);
92 len = 0;
93 }
94 if (wrap) {
95 tlen = len;
96 for (t = ep - 1, len = 0; t >= p; --t, ++len)
97 if (*t == '\n') {
98 if (len) {
99 WR(t + 1, len);
100 len = 0;
101 }
102 if (tlen) {
103 WR(sp, tlen);
104 tlen = 0;
105 }
106 }
107 if (len)
108 WR(t + 1, len);
109 if (tlen)
110 WR(sp, tlen);
111 }
112 } else {
113 if (wrap && (len = ep - p))
114 WR(p, len);
115 if ((len = p - sp) != 0)
116 WR(sp, len);
117 }
118 return 0;
119 }
120
121 /*
122 * displaylines -- read lines to an offset from the end and display.
123 *
124 * This is the function that reads to a line offset from the end of the input,
125 * storing the data in an array of buffers which is then displayed. If the
126 * rflag is set, the data is displayed in lines in reverse order, and this
127 * routine has the usual nastiness of trying to find the newlines. Otherwise,
128 * it is displayed from the line closest to the beginning of the input to
129 * the end.
130 *
131 * Non-zero return means than a (non-fatal) error occurred.
132 */
133 int
displaylines(FILE * fp,off_t off)134 displaylines(FILE *fp, off_t off)
135 {
136 struct {
137 int blen;
138 int len;
139 char *l;
140 } *lines;
141 int ch;
142 char *p;
143 int blen, cnt, recno, wrap;
144 char *sp, *n;
145
146 p = NULL;
147 if ((lines = malloc(off * sizeof(*lines))) == NULL)
148 xerr(1, "malloc");
149
150 memset(lines, 0, sizeof(*lines) * off);
151
152 sp = NULL;
153 blen = cnt = recno = wrap = 0;
154
155 while ((ch = getc(fp)) != EOF) {
156 if (++cnt > blen) {
157 if ((n = realloc(sp, blen + 1024)) == NULL)
158 xerr(1, "realloc");
159 sp = n;
160 blen += 1024;
161 p = sp + cnt - 1;
162 }
163 *p++ = ch;
164 if (ch == '\n') {
165 if (lines[recno].blen < cnt) {
166 if ((n = realloc(lines[recno].l,
167 cnt + 256)) == NULL)
168 xerr(1, "realloc");
169 lines[recno].l = n;
170 lines[recno].blen = cnt + 256;
171 }
172 memmove(lines[recno].l, sp, lines[recno].len = cnt);
173 cnt = 0;
174 p = sp;
175 if (++recno == off) {
176 wrap = 1;
177 recno = 0;
178 }
179 }
180 }
181 if (ferror(fp)) {
182 free(lines);
183 ierr();
184 return 1;
185 }
186 if (cnt) {
187 lines[recno].l = sp;
188 lines[recno].len = cnt;
189 if (++recno == off) {
190 wrap = 1;
191 recno = 0;
192 }
193 }
194
195 if (rflag) {
196 for (cnt = recno - 1; cnt >= 0; --cnt)
197 WR(lines[cnt].l, lines[cnt].len);
198 if (wrap)
199 for (cnt = off - 1; cnt >= recno; --cnt)
200 WR(lines[cnt].l, lines[cnt].len);
201 } else {
202 if (wrap)
203 for (cnt = recno; cnt < off; ++cnt)
204 WR(lines[cnt].l, lines[cnt].len);
205 for (cnt = 0; cnt < recno; ++cnt)
206 WR(lines[cnt].l, lines[cnt].len);
207 }
208 free(lines);
209 return 0;
210 }
211