1 /* $NetBSD: position.c,v 1.12 2001/11/26 00:56:33 enami 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. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 #include <sys/cdefs.h> 41 #ifndef lint 42 #if 0 43 static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94"; 44 #else 45 __RCSID("$NetBSD: position.c,v 1.12 2001/11/26 00:56:33 enami Exp $"); 46 #endif 47 #endif /* not lint */ 48 49 #include <sys/types.h> 50 #include <sys/stat.h> 51 #include <sys/ioctl.h> 52 #include <sys/mtio.h> 53 #include <sys/time.h> 54 55 #include <err.h> 56 #include <errno.h> 57 #include <string.h> 58 #include <unistd.h> 59 60 #include "dd.h" 61 #include "extern.h" 62 63 /* 64 * Position input/output data streams before starting the copy. Device type 65 * dependent. Seekable devices use lseek, and the rest position by reading. 66 * Seeking past the end of file can cause null blocks to be written to the 67 * output. 68 */ 69 void 70 pos_in(void) 71 { 72 int bcnt, cnt, nr, warned; 73 74 /* If not a pipe or tape device, try to seek on it. */ 75 if (!(in.flags & (ISPIPE|ISTAPE))) { 76 if (lseek(in.fd, 77 (off_t)in.offset * (off_t)in.dbsz, SEEK_CUR) == -1) 78 err(1, "%s", in.name); 79 return; 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 = read(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(1, "skip reached end of input"); 105 } 106 107 /* 108 * Input error -- either EOF with no more files, or I/O error. 109 * If noerror not set die. POSIX requires that the warning 110 * message be followed by an I/O display. 111 */ 112 if (ddflags & C_NOERROR) { 113 if (!warned) { 114 warn("%s", in.name); 115 warned = 1; 116 summary(); 117 } 118 continue; 119 } 120 err(1, "%s", in.name); 121 } 122 } 123 124 void 125 pos_out(void) 126 { 127 struct mtop t_op; 128 int cnt, n; 129 130 /* 131 * If not a tape, try seeking on the file. Seeking on a pipe is 132 * going to fail, but don't protect the user -- they shouldn't 133 * have specified the seek operand. 134 */ 135 if (!(out.flags & ISTAPE)) { 136 if (lseek(out.fd, 137 (off_t)out.offset * (off_t)out.dbsz, SEEK_SET) == -1) 138 err(1, "%s", out.name); 139 return; 140 } 141 142 /* If no read access, try using mtio. */ 143 if (out.flags & NOREAD) { 144 t_op.mt_op = MTFSR; 145 t_op.mt_count = out.offset; 146 147 if (ioctl(out.fd, MTIOCTOP, &t_op) < 0) 148 err(1, "%s", out.name); 149 return; 150 } 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 < 0) 158 err(1, "%s", out.name); 159 160 /* 161 * If reach EOF, fill with NUL characters; first, back up over 162 * the EOF mark. Note, cnt has not yet been incremented, so 163 * the EOF read does not count as a seek'd block. 164 */ 165 t_op.mt_op = MTBSR; 166 t_op.mt_count = 1; 167 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 168 err(1, "%s", out.name); 169 170 while (cnt++ < out.offset) 171 if ((n = bwrite(out.fd, out.db, out.dbsz)) != out.dbsz) 172 err(1, "%s", out.name); 173 break; 174 } 175 } 176