1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
/* $OpenBSD: position.c,v 1.7 2003/06/11 23:42:12 deraadt Exp $ */
/* $NetBSD: position.c,v 1.4 1995/03/21 09:04:12 cgd Exp $ */
/*-
* Copyright (c) 1991, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Keith Muller of the University of California, San Diego and Lance
* Visser of Convex Computer Corporation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94";
#else
static char rcsid[] = "$OpenBSD: position.c,v 1.7 2003/06/11 23:42:12 deraadt Exp $";
#endif
#endif /* not lint */
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/mtio.h>
#include <sys/time.h>
#include <err.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include "dd.h"
#include "extern.h"
/*
* Position input/output data streams before starting the copy. Device type
* dependent. Seekable devices use lseek, and the rest position by reading.
* Seeking past the end of file can cause null blocks to be written to the
* output.
*/
void
pos_in(void)
{
size_t bcnt;
ssize_t nr;
off_t cnt;
int warned;
/* If not a pipe or tape device, try to seek on it. */
if (!(in.flags & (ISPIPE|ISTAPE))) {
if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1)
err(1, "%s", in.name);
return;
}
/*
* Read the data. If a pipe, read until satisfy the number of bytes
* being skipped. No differentiation for reading complete and partial
* blocks for other devices.
*/
for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
if ((nr = read(in.fd, in.db, bcnt)) > 0) {
if (in.flags & ISPIPE) {
if (!(bcnt -= nr)) {
bcnt = in.dbsz;
--cnt;
}
} else
--cnt;
continue;
}
if (nr == 0) {
if (files_cnt > 1) {
--files_cnt;
continue;
}
errx(1, "skip reached end of input");
}
/*
* Input error -- either EOF with no more files, or I/O error.
* If noerror not set die. POSIX requires that the warning
* message be followed by an I/O display.
*/
if (ddflags & C_NOERROR) {
if (!warned) {
warn("%s", in.name);
warned = 1;
summary();
}
continue;
}
err(1, "%s", in.name);
}
}
void
pos_out(void)
{
struct mtop t_op;
off_t cnt;
ssize_t n;
/*
* If not a tape, try seeking on the file. Seeking on a pipe is
* going to fail, but don't protect the user -- they shouldn't
* have specified the seek operand.
*/
if (!(out.flags & ISTAPE)) {
if (lseek(out.fd, out.offset * out.dbsz, SEEK_SET) == -1)
err(1, "%s", out.name);
return;
}
/* If no read access, try using mtio. */
if (out.flags & NOREAD) {
t_op.mt_op = MTFSR;
t_op.mt_count = out.offset;
if (ioctl(out.fd, MTIOCTOP, &t_op) < 0)
err(1, "%s", out.name);
return;
}
/* Read it. */
for (cnt = 0; cnt < out.offset; ++cnt) {
if ((n = read(out.fd, out.db, out.dbsz)) > 0)
continue;
if (n < 0)
err(1, "%s", out.name);
/*
* If reach EOF, fill with NUL characters; first, back up over
* the EOF mark. Note, cnt has not yet been incremented, so
* the EOF read does not count as a seek'd block.
*/
t_op.mt_op = MTBSR;
t_op.mt_count = 1;
if (ioctl(out.fd, MTIOCTOP, &t_op) == -1)
err(1, "%s", out.name);
while (cnt++ < out.offset)
if ((n = write(out.fd, out.db, out.dbsz)) != out.dbsz)
err(1, "%s", out.name);
break;
}
}
|
