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 * 4. 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
33#include <sys/cdefs.h>
34
35__FBSDID("$FreeBSD$");
36
37#ifndef lint
38static const char sccsid[] = "@(#)read.c	8.1 (Berkeley) 6/6/93";
39#endif
40
41#include <sys/types.h>
42#include <sys/stat.h>
43
44#include <err.h>
45#include <errno.h>
46#include <fcntl.h>
47#include <stdio.h>
48#include <stdlib.h>
49#include <string.h>
50#include <unistd.h>
51
52#include "extern.h"
53
54/*
55 * bytes -- read bytes to an offset from the end and display.
56 *
57 * This is the function that reads to a byte offset from the end of the input,
58 * storing the data in a wrap-around buffer which is then displayed.  If the
59 * rflag is set, the data is displayed in lines in reverse order, and this
60 * routine has the usual nastiness of trying to find the newlines.  Otherwise,
61 * it is displayed from the character closest to the beginning of the input to
62 * the end.
63 */
64int
65bytes(FILE *fp, const char *fn, off_t off)
66{
67	int ch, len, tlen;
68	char *ep, *p, *t;
69	int wrap;
70	char *sp;
71
72	if ((sp = p = malloc(off)) == NULL)
73		err(1, "malloc");
74
75	for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) {
76		*p = ch;
77		if (++p == ep) {
78			wrap = 1;
79			p = sp;
80		}
81	}
82	if (ferror(fp)) {
83		ierr(fn);
84		free(sp);
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		len = p - sp;
116		if (len)
117			WR(sp, len);
118	}
119
120	free(sp);
121	return 0;
122}
123
124/*
125 * lines -- read lines to an offset from the end and display.
126 *
127 * This is the function that reads to a line offset from the end of the input,
128 * storing the data in an array of buffers which is then displayed.  If the
129 * rflag is set, the data is displayed in lines in reverse order, and this
130 * routine has the usual nastiness of trying to find the newlines.  Otherwise,
131 * it is displayed from the line closest to the beginning of the input to
132 * the end.
133 */
134int
135lines(FILE *fp, const char *fn, off_t off)
136{
137	struct {
138		int blen;
139		u_int len;
140		char *l;
141	} *llines;
142	int ch, rc;
143	char *p, *sp;
144	int blen, cnt, recno, wrap;
145
146	if ((llines = calloc(off, sizeof(*llines))) == NULL)
147		err(1, "calloc");
148	p = sp = NULL;
149	blen = cnt = recno = wrap = 0;
150	rc = 0;
151
152	while ((ch = getc(fp)) != EOF) {
153		if (++cnt > blen) {
154			if ((sp = realloc(sp, blen += 1024)) == NULL)
155				err(1, "realloc");
156			p = sp + cnt - 1;
157		}
158		*p++ = ch;
159		if (ch == '\n') {
160			if ((int)llines[recno].blen < cnt) {
161				llines[recno].blen = cnt + 256;
162				if ((llines[recno].l = realloc(llines[recno].l,
163				    llines[recno].blen)) == NULL)
164					err(1, "realloc");
165			}
166			bcopy(sp, llines[recno].l, llines[recno].len = cnt);
167			cnt = 0;
168			p = sp;
169			if (++recno == off) {
170				wrap = 1;
171				recno = 0;
172			}
173		}
174	}
175	if (ferror(fp)) {
176		ierr(fn);
177		rc = 1;
178		goto done;
179	}
180	if (cnt) {
181		llines[recno].l = sp;
182		sp = NULL;
183		llines[recno].len = cnt;
184		if (++recno == off) {
185			wrap = 1;
186			recno = 0;
187		}
188	}
189
190	if (rflag) {
191		for (cnt = recno - 1; cnt >= 0; --cnt)
192			WR(llines[cnt].l, llines[cnt].len);
193		if (wrap)
194			for (cnt = off - 1; cnt >= recno; --cnt)
195				WR(llines[cnt].l, llines[cnt].len);
196	} else {
197		if (wrap)
198			for (cnt = recno; cnt < off; ++cnt)
199				WR(llines[cnt].l, llines[cnt].len);
200		for (cnt = 0; cnt < recno; ++cnt)
201			WR(llines[cnt].l, llines[cnt].len);
202	}
203done:
204	for (cnt = 0; cnt < off; cnt++)
205		free(llines[cnt].l);
206	free(sp);
207	free(llines);
208	return (rc);
209}
210