1/*	$NetBSD: read.c,v 1.16 2011/09/03 09:02:20 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
38static char sccsid[] = "@(#)read.c	8.1 (Berkeley) 6/6/93";
39#endif
40__RCSID("$NetBSD: read.c,v 1.16 2011/09/03 09:02:20 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 */
65int
66displaybytes(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 */
133int
134displaylines(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