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984263bc MD |
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. | |
1902d433 | 17 | * 3. Neither the name of the University nor the names of its contributors |
984263bc MD |
18 | * may be used to endorse or promote products derived from this software |
19 | * without specific prior written permission. | |
20 | * | |
21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
31 | * SUCH DAMAGE. | |
1de703da MD |
32 | * |
33 | * @(#)position.c 8.3 (Berkeley) 4/2/94 | |
34 | * $FreeBSD: src/bin/dd/position.c,v 1.17.2.2 2001/01/23 14:23:55 asmodai Exp $ | |
1902d433 | 35 | * $DragonFly: src/bin/dd/position.c,v 1.4 2008/01/28 16:08:02 matthias Exp $ |
984263bc MD |
36 | */ |
37 | ||
984263bc MD |
38 | #include <sys/types.h> |
39 | #include <sys/mtio.h> | |
40 | ||
41 | #include <err.h> | |
42 | #include <errno.h> | |
43 | #include <unistd.h> | |
44 | ||
45 | #include "dd.h" | |
46 | #include "extern.h" | |
47 | ||
48 | /* | |
49 | * Position input/output data streams before starting the copy. Device type | |
50 | * dependent. Seekable devices use lseek, and the rest position by reading. | |
51 | * Seeking past the end of file can cause null blocks to be written to the | |
52 | * output. | |
53 | */ | |
54 | void | |
b5744197 | 55 | pos_in(void) |
984263bc MD |
56 | { |
57 | off_t cnt; | |
58 | int warned; | |
59 | ssize_t nr; | |
60 | size_t bcnt; | |
61 | ||
62 | /* If known to be seekable, try to seek on it. */ | |
63 | if (in.flags & ISSEEK) { | |
64 | errno = 0; | |
65 | if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1 && | |
66 | errno != 0) | |
67 | err(1, "%s", in.name); | |
68 | return; | |
69 | } | |
70 | ||
71 | /* Don't try to read a really weird amount (like negative). */ | |
72 | if (in.offset < 0) | |
73 | errx(1, "%s: illegal offset", "iseek/skip"); | |
74 | ||
75 | /* | |
76 | * Read the data. If a pipe, read until satisfy the number of bytes | |
77 | * being skipped. No differentiation for reading complete and partial | |
78 | * blocks for other devices. | |
79 | */ | |
80 | for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { | |
81 | if ((nr = read(in.fd, in.db, bcnt)) > 0) { | |
82 | if (in.flags & ISPIPE) { | |
83 | if (!(bcnt -= nr)) { | |
84 | bcnt = in.dbsz; | |
85 | --cnt; | |
86 | } | |
87 | } else | |
88 | --cnt; | |
89 | continue; | |
90 | } | |
91 | ||
92 | if (nr == 0) { | |
93 | if (files_cnt > 1) { | |
94 | --files_cnt; | |
95 | continue; | |
96 | } | |
97 | errx(1, "skip reached end of input"); | |
98 | } | |
99 | ||
100 | /* | |
101 | * Input error -- either EOF with no more files, or I/O error. | |
102 | * If noerror not set die. POSIX requires that the warning | |
103 | * message be followed by an I/O display. | |
104 | */ | |
105 | if (ddflags & C_NOERROR) { | |
106 | if (!warned) { | |
107 | warn("%s", in.name); | |
108 | warned = 1; | |
109 | summary(); | |
110 | } | |
111 | continue; | |
112 | } | |
113 | err(1, "%s", in.name); | |
114 | } | |
115 | } | |
116 | ||
117 | void | |
b5744197 | 118 | pos_out(void) |
984263bc MD |
119 | { |
120 | struct mtop t_op; | |
121 | off_t cnt; | |
122 | ssize_t n; | |
123 | ||
124 | /* | |
125 | * If not a tape, try seeking on the file. Seeking on a pipe is | |
126 | * going to fail, but don't protect the user -- they shouldn't | |
127 | * have specified the seek operand. | |
128 | */ | |
129 | if (out.flags & (ISSEEK | ISPIPE)) { | |
130 | errno = 0; | |
131 | if (lseek(out.fd, out.offset * out.dbsz, SEEK_CUR) == -1 && | |
132 | errno != 0) | |
133 | err(1, "%s", out.name); | |
134 | return; | |
135 | } | |
136 | ||
137 | /* Don't try to read a really weird amount (like negative). */ | |
138 | if (out.offset < 0) | |
139 | errx(1, "%s: illegal offset", "oseek/seek"); | |
140 | ||
141 | /* If no read access, try using mtio. */ | |
142 | if (out.flags & NOREAD) { | |
143 | t_op.mt_op = MTFSR; | |
144 | t_op.mt_count = out.offset; | |
145 | ||
146 | if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) | |
147 | err(1, "%s", out.name); | |
148 | return; | |
149 | } | |
150 | ||
151 | /* Read it. */ | |
152 | for (cnt = 0; cnt < out.offset; ++cnt) { | |
153 | if ((n = read(out.fd, out.db, out.dbsz)) > 0) | |
154 | continue; | |
155 | ||
156 | if (n == -1) | |
157 | err(1, "%s", out.name); | |
158 | ||
159 | /* | |
160 | * If reach EOF, fill with NUL characters; first, back up over | |
161 | * the EOF mark. Note, cnt has not yet been incremented, so | |
162 | * the EOF read does not count as a seek'd block. | |
163 | */ | |
164 | t_op.mt_op = MTBSR; | |
165 | t_op.mt_count = 1; | |
166 | if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) | |
167 | err(1, "%s", out.name); | |
168 | ||
169 | while (cnt++ < out.offset) { | |
170 | n = write(out.fd, out.db, out.dbsz); | |
171 | if (n == -1) | |
172 | err(1, "%s", out.name); | |
173 | if ((size_t)n != out.dbsz) | |
174 | errx(1, "%s: write failure", out.name); | |
175 | } | |
176 | break; | |
177 | } | |
178 | } |