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
39static 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 */
66void
67pos_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
127void
128pos_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