xio.c revision 50479 
1/*
2 * Copyright (c) 1999 Global Technology Associates, Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
18 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
19 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
20 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
21 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
22 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
23 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
24 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * $FreeBSD: head/usr.sbin/kgzip/xio.c 50479 1999-08-28 01:35:59Z peter $
27 */
28
29#include <err.h>
30#include <fcntl.h>
31#include <string.h>
32#include <unistd.h>
33
34#include "kgzip.h"
35
36/*
37 * Close a file.
38 */
39void
40xclose(const struct iodesc *id)
41{
42    if (close(id->fd))
43	err(1, "%s", id->fname);
44}
45
46/*
47 * Copy bytes from one file to another.
48 */
49void
50xcopy(const struct iodesc * idi, const struct iodesc * ido,
51      size_t nbyte, off_t offset)
52{
53    char buf[8192];
54    size_t n;
55
56    while (nbyte) {
57	if ((n = sizeof(buf)) > nbyte)
58	    n = nbyte;
59	if (xread(idi, buf, n, offset) != n)
60	    errx(1, "%s: Short read", idi->fname);
61	xwrite(ido, buf, n);
62	nbyte -= n;
63	offset = -1;
64    }
65}
66
67/*
68 * Write binary zeroes to a file.
69 */
70void
71xzero(const struct iodesc * id, size_t nbyte)
72{
73    char buf[8192];
74    size_t n;
75
76    memset(buf, 0, sizeof(buf));
77    while (nbyte) {
78	if ((n = sizeof(buf)) > nbyte)
79	    n = nbyte;
80	xwrite(id, buf, n);
81	nbyte -= n;
82    }
83}
84
85/*
86 * Read from a file.
87 */
88size_t
89xread(const struct iodesc * id, void *buf, size_t nbyte, off_t offset)
90{
91    ssize_t n;
92
93    if (offset != -1 && lseek(id->fd, offset, SEEK_SET) != offset)
94	err(1, "%s", id->fname);
95    if ((n = read(id->fd, buf, nbyte)) == -1)
96	err(1, "%s", id->fname);
97    return (size_t)n;
98}
99
100/*
101 * Write to a file.
102 */
103void
104xwrite(const struct iodesc * id, const void *buf, size_t nbyte)
105{
106    ssize_t n;
107
108    if ((n = write(id->fd, buf, nbyte)) == -1)
109	err(1, "%s", id->fname);
110    if ((size_t)n != nbyte)
111	errx(1, "%s: Short write", id->fname);
112}
113
114/*
115 * Reposition within a file.
116 */
117void
118xseek(const struct iodesc *id, off_t offset)
119{
120    if (lseek(id->fd, offset, SEEK_SET) != offset)
121	err(1, "%s", id->fname);
122}
123