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#include <sys/cdefs.h>
39#ifndef lint
40#if 0
41static char sccsid[] = "@(#)position.c	8.3 (Berkeley) 4/2/94";
42#endif
43__used static const char rcsid[] =
44  "$FreeBSD: src/bin/dd/position.c,v 1.20 2002/02/02 06:24:12 imp Exp $";
45#endif /* not lint */
46
47#include <sys/types.h>
48
49#ifdef __APPLE__
50#include <sys/ioctl.h>
51#endif
52
53#include <err.h>
54#include <errno.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 */
66void
67pos_in(void)
68{
69	off_t cnt;
70	int warned;
71	ssize_t nr;
72	size_t bcnt;
73
74	/* If known to be seekable, try to seek on it. */
75	if (in.flags & ISSEEK) {
76		errno = 0;
77		if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1 &&
78		    errno != 0)
79			err(1, "%s", in.name);
80		return;
81	}
82
83	/* Don't try to read a really weird amount (like negative). */
84	if (in.offset < 0)
85		errx(1, "%s: illegal offset", "iseek/skip");
86
87	/*
88	 * Read the data.  If a pipe, read until satisfy the number of bytes
89	 * being skipped.  No differentiation for reading complete and partial
90	 * blocks for other devices.
91	 */
92	for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
93		if ((nr = read(in.fd, in.db, bcnt)) > 0) {
94			if (in.flags & ISPIPE) {
95				if (!(bcnt -= nr)) {
96					bcnt = in.dbsz;
97					--cnt;
98				}
99			} else
100				--cnt;
101			continue;
102		}
103
104		if (nr == 0) {
105			if (files_cnt > 1) {
106				--files_cnt;
107				continue;
108			}
109			errx(1, "skip reached end of input");
110		}
111
112		/*
113		 * Input error -- either EOF with no more files, or I/O error.
114		 * If noerror not set die.  POSIX requires that the warning
115		 * message be followed by an I/O display.
116		 */
117		if (ddflags & C_NOERROR) {
118			if (!warned) {
119				warn("%s", in.name);
120				warned = 1;
121				summary();
122			}
123			continue;
124		}
125		err(1, "%s", in.name);
126	}
127}
128
129void
130pos_out(void)
131{
132	off_t cnt;
133	ssize_t n;
134
135	/*
136	 * If not a tape, try seeking on the file.  Seeking on a pipe is
137	 * going to fail, but don't protect the user -- they shouldn't
138	 * have specified the seek operand.
139	 */
140	if (out.flags & (ISSEEK | ISPIPE)) {
141		errno = 0;
142		if (lseek(out.fd, out.offset * out.dbsz, SEEK_CUR) == -1 &&
143		    errno != 0)
144			err(1, "%s", out.name);
145		return;
146	}
147
148	/* Don't try to read a really weird amount (like negative). */
149	if (out.offset < 0)
150		errx(1, "%s: illegal offset", "oseek/seek");
151
152	/* Read it. */
153	for (cnt = 0; cnt < out.offset; ++cnt) {
154		if ((n = read(out.fd, out.db, out.dbsz)) > 0)
155			continue;
156
157		if (n == -1)
158			err(1, "%s", out.name);
159
160		while (cnt++ < out.offset) {
161			n = write(out.fd, out.db, out.dbsz);
162			if (n == -1)
163				err(1, "%s", out.name);
164			if ((size_t)n != out.dbsz)
165				errx(1, "%s: write failure", out.name);
166		}
167		break;
168	}
169}
170