1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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/types.h>
37 #include <sys/mtio.h>
38
39 #include <err.h>
40 #include <errno.h>
41 #include <inttypes.h>
42 #include <limits.h>
43 #include <signal.h>
44 #include <unistd.h>
45
46 #include "dd.h"
47 #include "extern.h"
48
49 static off_t
seek_offset(IO * io)50 seek_offset(IO *io)
51 {
52 off_t n;
53 size_t sz;
54
55 n = io->offset;
56 sz = io->dbsz;
57
58 _Static_assert(sizeof(io->offset) == sizeof(int64_t), "64-bit off_t");
59
60 /*
61 * If the lseek offset will be negative, verify that this is a special
62 * device file. Some such files (e.g. /dev/kmem) permit "negative"
63 * offsets.
64 *
65 * Bail out if the calculation of a file offset would overflow.
66 */
67 if ((io->flags & ISCHR) == 0 && (n < 0 || n > OFF_MAX / (ssize_t)sz))
68 errx(1, "seek offsets cannot be larger than %jd",
69 (intmax_t)OFF_MAX);
70 else if ((io->flags & ISCHR) != 0 && (uint64_t)n > UINT64_MAX / sz)
71 errx(1, "seek offsets cannot be larger than %ju",
72 (uintmax_t)UINT64_MAX);
73
74 return ((off_t)( (uint64_t)n * sz ));
75 }
76
77 /*
78 * Position input/output data streams before starting the copy. Device type
79 * dependent. Seekable devices use lseek, and the rest position by reading.
80 * Seeking past the end of file can cause null blocks to be written to the
81 * output.
82 */
83 void
pos_in(void)84 pos_in(void)
85 {
86 off_t cnt;
87 int warned;
88 ssize_t nr;
89 size_t bcnt;
90
91 /* If known to be seekable, try to seek on it. */
92 if (in.flags & ISSEEK) {
93 errno = 0;
94 if (lseek(in.fd, seek_offset(&in), SEEK_CUR) == -1 &&
95 errno != 0)
96 err(1, "%s", in.name);
97 return;
98 }
99
100 /* Don't try to read a really weird amount (like negative). */
101 if (in.offset < 0)
102 errx(1, "%s: illegal offset", "iseek/skip");
103
104 /*
105 * Read the data. If a pipe, read until satisfy the number of bytes
106 * being skipped. No differentiation for reading complete and partial
107 * blocks for other devices.
108 */
109 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
110 if ((nr = read(in.fd, in.db, bcnt)) > 0) {
111 if (in.flags & ISPIPE) {
112 if (!(bcnt -= nr)) {
113 bcnt = in.dbsz;
114 --cnt;
115 }
116 } else
117 --cnt;
118 if (need_summary)
119 summary();
120 if (need_progress)
121 progress();
122 continue;
123 }
124
125 if (nr == 0) {
126 if (files_cnt > 1) {
127 --files_cnt;
128 continue;
129 }
130 errx(1, "skip reached end of input");
131 }
132
133 /*
134 * Input error -- either EOF with no more files, or I/O error.
135 * If noerror not set die. POSIX requires that the warning
136 * message be followed by an I/O display.
137 */
138 if (ddflags & C_NOERROR) {
139 if (!warned) {
140 warn("%s", in.name);
141 warned = 1;
142 summary();
143 }
144 continue;
145 }
146 err(1, "%s", in.name);
147 }
148 }
149
150 void
pos_out(void)151 pos_out(void)
152 {
153 struct mtop t_op;
154 off_t cnt;
155 ssize_t n;
156
157 /*
158 * If not a tape, try seeking on the file. Seeking on a pipe is
159 * going to fail, but don't protect the user -- they shouldn't
160 * have specified the seek operand.
161 */
162 if (out.flags & (ISSEEK | ISPIPE)) {
163 errno = 0;
164 if (lseek(out.fd, seek_offset(&out), SEEK_CUR) == -1 &&
165 errno != 0)
166 err(1, "%s", out.name);
167 return;
168 }
169
170 /* Don't try to read a really weird amount (like negative). */
171 if (out.offset < 0)
172 errx(1, "%s: illegal offset", "oseek/seek");
173
174 /* If no read access, try using mtio. */
175 if (out.flags & NOREAD) {
176 t_op.mt_op = MTFSR;
177 t_op.mt_count = out.offset;
178
179 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1)
180 err(1, "%s", out.name);
181 return;
182 }
183
184 /* Read it. */
185 for (cnt = 0; cnt < out.offset; ++cnt) {
186 before_io();
187 n = read(out.fd, out.db, out.dbsz);
188 after_io();
189 if (n > 0)
190 continue;
191 if (n == -1)
192 err(1, "%s", out.name);
193
194 /*
195 * If reach EOF, fill with NUL characters; first, back up over
196 * the EOF mark. Note, cnt has not yet been incremented, so
197 * the EOF read does not count as a seek'd block.
198 */
199 t_op.mt_op = MTBSR;
200 t_op.mt_count = 1;
201 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1)
202 err(1, "%s", out.name);
203
204 while (cnt++ < out.offset) {
205 before_io();
206 n = write(out.fd, out.db, out.dbsz);
207 after_io();
208 if (n == -1)
209 err(1, "%s", out.name);
210 if (n != out.dbsz)
211 errx(1, "%s: write failure", out.name);
212 }
213 break;
214 }
215 }
216