1/*-
2 * Copyright (c) 1991, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Keith Muller of the University of California, San Diego and Lance
7 * Visser of Convex Computer Corporation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by the University of
20 * California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38#ifndef lint
39#if 0
40static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94";
41#endif
42static const char rcsid[] =
43 "$Id: position.c,v 1.7 1998/05/06 06:51:42 charnier Exp $";
44#endif /* not lint */
45
46#include <sys/types.h>
47#include <sys/mtio.h>
48
49#include <err.h>
50#include <unistd.h>
51
52#include "dd.h"
53#include "extern.h"
54
55/*
56 * Position input/output data streams before starting the copy. Device type
57 * dependent. Seekable devices use lseek, and the rest position by reading.
58 * Seeking past the end of file can cause null blocks to be written to the
59 * output.
60 */
61void
62pos_in()
63{
64 int bcnt, cnt, nr, warned;
65
66 /* If not a character, pipe or tape device, try to seek on it. */
67 if (!(in.flags & (ISCHR|ISPIPE|ISTAPE))) {
68 if (lseek(in.fd, (off_t)in.offset * in.dbsz, SEEK_CUR) == -1)
69 err(1, "%s", in.name);
70 return;
71 }
72
73 /*
74 * Read the data. If a pipe, read until satisfy the number of bytes
75 * being skipped. No differentiation for reading complete and partial
76 * blocks for other devices.
77 */
78 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
79 if ((nr = read(in.fd, in.db, bcnt)) > 0) {
80 if (in.flags & ISPIPE) {
81 if (!(bcnt -= nr)) {
82 bcnt = in.dbsz;
83 --cnt;
84 }
85 } else
86 --cnt;
87 continue;
88 }
89
90 if (nr == 0) {
91 if (files_cnt > 1) {
92 --files_cnt;
93 continue;
94 }
95 errx(1, "skip reached end of input");
96 }
97
98 /*
99 * Input error -- either EOF with no more files, or I/O error.
100 * If noerror not set die. POSIX requires that the warning
101 * message be followed by an I/O display.
102 */
103 if (ddflags & C_NOERROR) {
104 if (!warned) {
105 warn("%s", in.name);
106 warned = 1;
107 summary();
108 }
109 continue;
110 }
111 err(1, "%s", in.name);
112 }
113}
114
115void
116pos_out()
117{
118 struct mtop t_op;
119 int cnt, n;
120
121 /*
122 * If not a tape, try seeking on the file. Seeking on a pipe is
123 * going to fail, but don't protect the user -- they shouldn't
124 * have specified the seek operand.
125 */
126 if (!(out.flags & ISTAPE)) {
127 if (lseek(out.fd,
128 (off_t)out.offset * out.dbsz, SEEK_SET) == -1)
129 err(1, "%s", out.name);
130 return;
131 }
132
133 /* If no read access, try using mtio. */
134 if (out.flags & NOREAD) {
135 t_op.mt_op = MTFSR;
136 t_op.mt_count = out.offset;
137
138 if (ioctl(out.fd, MTIOCTOP, &t_op) < 0)
139 err(1, "%s", out.name);
140 return;
141 }
142
143 /* Read it. */
144 for (cnt = 0; cnt < out.offset; ++cnt) {
145 if ((n = read(out.fd, out.db, out.dbsz)) > 0)
146 continue;
147
148 if (n < 0)
149 err(1, "%s", out.name);
150
151 /*
152 * If reach EOF, fill with NUL characters; first, back up over
153 * the EOF mark. Note, cnt has not yet been incremented, so
154 * the EOF read does not count as a seek'd block.
155 */
156 t_op.mt_op = MTBSR;
157 t_op.mt_count = 1;
158 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1)
159 err(1, "%s", out.name);
160
161 while (cnt++ < out.offset)
162 if ((n = write(out.fd, out.db, out.dbsz)) != out.dbsz)
163 err(1, "%s", out.name);
164 break;
165 }
166}