2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Edward Sze-Tyan Wang.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
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 $
37 #include <sys/types.h>
49 * display_bytes -- read bytes to an offset from the end and display.
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
59 display_bytes(FILE *fp
, off_t off
)
66 if ((sp
= p
= malloc(off
)) == NULL
)
69 for (wrap
= 0, ep
= p
+ off
; (ch
= getc(fp
)) != EOF
;) {
83 for (t
= p
- 1, len
= 0; t
>= sp
; --t
, ++len
)
84 if (*t
== '\n' && len
) {
90 for (t
= ep
- 1, len
= 0; t
>= p
; --t
, ++len
)
107 if (wrap
&& (len
= ep
- p
))
109 if ((len
= p
- sp
) != 0)
117 * display_lines -- read lines to an offset from the end and display.
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
127 display_lines(FILE *fp
, off_t off
)
136 int blen
, cnt
, recno
, wrap
;
139 if ((lines
= malloc(off
* sizeof(*lines
))) == NULL
)
141 bzero(lines
, off
* sizeof(*lines
));
143 blen
= cnt
= recno
= wrap
= 0;
145 while ((ch
= getc(fp
)) != EOF
) {
147 if ((sp
= realloc(sp
, blen
+= 1024)) == NULL
)
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
)
159 bcopy(sp
, lines
[recno
].l
, lines
[recno
].len
= cnt
);
162 if (++recno
== off
) {
176 lines
[recno
].len
= cnt
;
177 if (++recno
== off
) {
184 for (cnt
= recno
- 1; cnt
>= 0; --cnt
)
185 WR(lines
[cnt
].l
, lines
[cnt
].len
);
187 for (cnt
= off
- 1; cnt
>= recno
; --cnt
)
188 WR(lines
[cnt
].l
, lines
[cnt
].len
);
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
);
197 for (cnt
= 0; cnt
< off
; cnt
++)