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