read.c revision 17341 
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. 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.
23 *
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
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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
34 * SUCH DAMAGE.
35 */
36
37#ifndef lint
38static char sccsid[] = "@(#)read.c	8.1 (Berkeley) 6/6/93";
39#endif /* not lint */
40
41#include <sys/types.h>
42#include <sys/stat.h>
43#include <fcntl.h>
44#include <errno.h>
45#include <unistd.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include <string.h>
49#include "extern.h"
50
51/*
52 * bytes -- read bytes to an offset from the end and display.
53 *
54 * This is the function that reads to a byte offset from the end of the input,
55 * storing the data in a wrap-around buffer which is then displayed.  If the
56 * rflag is set, the data is displayed in lines in reverse order, and this
57 * routine has the usual nastiness of trying to find the newlines.  Otherwise,
58 * it is displayed from the character closest to the beginning of the input to
59 * the end.
60 */
61int
62bytes(fp, off)
63	register FILE *fp;
64	off_t off;
65{
66	register int ch, len, tlen;
67	register char *ep, *p, *t;
68	int wrap;
69	char *sp;
70
71	if ((sp = p = malloc(off)) == NULL)
72		err(1, "%s", strerror(errno));
73
74	for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) {
75		*p = ch;
76		if (++p == ep) {
77			wrap = 1;
78			p = sp;
79		}
80	}
81	if (ferror(fp)) {
82		ierr();
83		return 1;
84	}
85
86	if (rflag) {
87		for (t = p - 1, len = 0; t >= sp; --t, ++len)
88			if (*t == '\n' && len) {
89				WR(t + 1, len);
90				len = 0;
91		}
92		if (wrap) {
93			tlen = len;
94			for (t = ep - 1, len = 0; t >= p; --t, ++len)
95				if (*t == '\n') {
96					if (len) {
97						WR(t + 1, len);
98						len = 0;
99					}
100					if (tlen) {
101						WR(sp, tlen);
102						tlen = 0;
103					}
104				}
105			if (len)
106				WR(t + 1, len);
107			if (tlen)
108				WR(sp, tlen);
109		}
110	} else {
111		if (wrap && (len = ep - p))
112			WR(p, len);
113		if (len = p - sp)
114			WR(sp, len);
115	}
116	return 0;
117}
118
119/*
120 * lines -- read lines to an offset from the end and display.
121 *
122 * This is the function that reads to a line offset from the end of the input,
123 * storing the data in an array of buffers which is then displayed.  If the
124 * rflag is set, the data is displayed in lines in reverse order, and this
125 * routine has the usual nastiness of trying to find the newlines.  Otherwise,
126 * it is displayed from the line closest to the beginning of the input to
127 * the end.
128 */
129int
130lines(fp, off)
131	register FILE *fp;
132	off_t off;
133{
134	struct {
135		u_int blen;
136		u_int len;
137		char *l;
138	} *lines;
139	register int ch;
140	register char *p;
141	int blen, cnt, recno, wrap;
142	char *sp;
143
144	if ((lines = malloc(off * sizeof(*lines))) == NULL)
145		err(1, "%s", strerror(errno));
146	bzero(lines, off * sizeof(*lines));
147	sp = NULL;
148	blen = cnt = recno = wrap = 0;
149
150	while ((ch = getc(fp)) != EOF) {
151		if (++cnt > blen) {
152			if ((sp = realloc(sp, blen += 1024)) == NULL)
153				err(1, "%s", strerror(errno));
154			p = sp + cnt - 1;
155		}
156		*p++ = ch;
157		if (ch == '\n') {
158			if (lines[recno].blen < cnt) {
159				lines[recno].blen = cnt + 256;
160				if ((lines[recno].l = realloc(lines[recno].l,
161				    lines[recno].blen)) == NULL)
162					err(1, "%s", strerror(errno));
163			}
164			bcopy(sp, lines[recno].l, lines[recno].len = cnt);
165			cnt = 0;
166			p = sp;
167			if (++recno == off) {
168				wrap = 1;
169				recno = 0;
170			}
171		}
172	}
173	if (ferror(fp)) {
174		ierr();
175		return 1;
176	}
177	if (cnt) {
178		lines[recno].l = sp;
179		lines[recno].len = cnt;
180		if (++recno == off) {
181			wrap = 1;
182			recno = 0;
183		}
184	}
185
186	if (rflag) {
187		for (cnt = recno - 1; cnt >= 0; --cnt)
188			WR(lines[cnt].l, lines[cnt].len);
189		if (wrap)
190			for (cnt = off - 1; cnt >= recno; --cnt)
191				WR(lines[cnt].l, lines[cnt].len);
192	} else {
193		if (wrap)
194			for (cnt = recno; cnt < off; ++cnt)
195				WR(lines[cnt].l, lines[cnt].len);
196		for (cnt = 0; cnt < recno; ++cnt)
197			WR(lines[cnt].l, lines[cnt].len);
198	}
199	return 0;
200}
201