1 /* $NetBSD: position.c,v 1.18 2010/11/22 21:04:28 pooka Exp $ */
2
3 /*-
4 * Copyright (c) 1991, 1993, 1994
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Keith Muller of the University of California, San Diego and Lance
9 * Visser of Convex Computer Corporation.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include <sys/cdefs.h>
37 #ifndef lint
38 #if 0
39 static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94";
40 #else
41 __RCSID("$NetBSD: position.c,v 1.18 2010/11/22 21:04:28 pooka Exp $");
42 #endif
43 #endif /* not lint */
44
45 #include <sys/types.h>
46 #include <sys/stat.h>
47 #include <sys/ioctl.h>
48 #include <sys/mtio.h>
49 #include <sys/time.h>
50
51 #include <err.h>
52 #include <errno.h>
53 #include <stdlib.h>
54 #include <string.h>
55 #include <unistd.h>
56
57 #include "dd.h"
58 #include "extern.h"
59
60 /*
61 * Position input/output data streams before starting the copy. Device type
62 * dependent. Seekable devices use lseek, and the rest position by reading.
63 * Seeking past the end of file can cause null blocks to be written to the
64 * output.
65 */
66 void
pos_in(void)67 pos_in(void)
68 {
69 int bcnt, cnt, nr, warned;
70
71 /* If not a pipe or tape device, try to seek on it. */
72 if (!(in.flags & (ISPIPE|ISTAPE))) {
73 if (ddop_lseek(in, in.fd,
74 (off_t)in.offset * (off_t)in.dbsz, SEEK_CUR) == -1) {
75 err(EXIT_FAILURE, "%s", in.name);
76 /* NOTREACHED */
77 }
78 return;
79 /* NOTREACHED */
80 }
81
82 /*
83 * Read the data. If a pipe, read until satisfy the number of bytes
84 * being skipped. No differentiation for reading complete and partial
85 * blocks for other devices.
86 */
87 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
88 if ((nr = ddop_read(in, in.fd, in.db, bcnt)) > 0) {
89 if (in.flags & ISPIPE) {
90 if (!(bcnt -= nr)) {
91 bcnt = in.dbsz;
92 --cnt;
93 }
94 } else
95 --cnt;
96 continue;
97 }
98
99 if (nr == 0) {
100 if (files_cnt > 1) {
101 --files_cnt;
102 continue;
103 }
104 errx(EXIT_FAILURE, "skip reached end of input");
105 /* NOTREACHED */
106 }
107
108 /*
109 * Input error -- either EOF with no more files, or I/O error.
110 * If noerror not set die. POSIX requires that the warning
111 * message be followed by an I/O display.
112 */
113 if (ddflags & C_NOERROR) {
114 if (!warned) {
115
116 warn("%s", in.name);
117 warned = 1;
118 summary();
119 }
120 continue;
121 }
122 err(EXIT_FAILURE, "%s", in.name);
123 /* NOTREACHED */
124 }
125 }
126
127 void
pos_out(void)128 pos_out(void)
129 {
130 struct mtop t_op;
131 int n;
132 uint64_t cnt;
133
134 /*
135 * If not a tape, try seeking on the file. Seeking on a pipe is
136 * going to fail, but don't protect the user -- they shouldn't
137 * have specified the seek operand.
138 */
139 if (!(out.flags & ISTAPE)) {
140 if (ddop_lseek(out, out.fd,
141 (off_t)out.offset * (off_t)out.dbsz, SEEK_SET) == -1)
142 err(EXIT_FAILURE, "%s", out.name);
143 /* NOTREACHED */
144 return;
145 }
146
147 /* If no read access, try using mtio. */
148 if (out.flags & NOREAD) {
149 t_op.mt_op = MTFSR;
150 t_op.mt_count = out.offset;
151
152 if (ddop_ioctl(out, out.fd, MTIOCTOP, &t_op) < 0)
153 err(EXIT_FAILURE, "%s", out.name);
154 /* NOTREACHED */
155 return;
156 }
157
158 /* Read it. */
159 for (cnt = 0; cnt < out.offset; ++cnt) {
160 if ((n = ddop_read(out, out.fd, out.db, out.dbsz)) > 0)
161 continue;
162
163 if (n < 0)
164 err(EXIT_FAILURE, "%s", out.name);
165 /* NOTREACHED */
166
167 /*
168 * If reach EOF, fill with NUL characters; first, back up over
169 * the EOF mark. Note, cnt has not yet been incremented, so
170 * the EOF read does not count as a seek'd block.
171 */
172 t_op.mt_op = MTBSR;
173 t_op.mt_count = 1;
174 if (ddop_ioctl(out, out.fd, MTIOCTOP, &t_op) == -1)
175 err(EXIT_FAILURE, "%s", out.name);
176 /* NOTREACHED */
177
178 while (cnt++ < out.offset)
179 if ((uint64_t)(n = bwrite(&out,
180 out.db, out.dbsz)) != out.dbsz)
181 err(EXIT_FAILURE, "%s", out.name);
182 /* NOTREACHED */
183 break;
184 }
185 }
186