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 39 static 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 */ 66 void 67 pos_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 } 126 127 void 128 pos_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
