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 * @(#)position.c 8.3 (Berkeley) 4/2/94 38 * $FreeBSD: src/bin/dd/position.c,v 1.17.2.2 2001/01/23 14:23:55 asmodai Exp $ 39 * $DragonFly: src/bin/dd/position.c,v 1.3 2003/09/28 14:39:13 hmp Exp $ 40 */ 41 42 #include <sys/types.h> 43 #include <sys/mtio.h> 44 45 #include <err.h> 46 #include <errno.h> 47 #include <unistd.h> 48 49 #include "dd.h" 50 #include "extern.h" 51 52 /* 53 * Position input/output data streams before starting the copy. Device type 54 * dependent. Seekable devices use lseek, and the rest position by reading. 55 * Seeking past the end of file can cause null blocks to be written to the 56 * output. 57 */ 58 void 59 pos_in(void) 60 { 61 off_t cnt; 62 int warned; 63 ssize_t nr; 64 size_t bcnt; 65 66 /* If known to be seekable, try to seek on it. */ 67 if (in.flags & ISSEEK) { 68 errno = 0; 69 if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1 && 70 errno != 0) 71 err(1, "%s", in.name); 72 return; 73 } 74 75 /* Don't try to read a really weird amount (like negative). */ 76 if (in.offset < 0) 77 errx(1, "%s: illegal offset", "iseek/skip"); 78 79 /* 80 * Read the data. If a pipe, read until satisfy the number of bytes 81 * being skipped. No differentiation for reading complete and partial 82 * blocks for other devices. 83 */ 84 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { 85 if ((nr = read(in.fd, in.db, bcnt)) > 0) { 86 if (in.flags & ISPIPE) { 87 if (!(bcnt -= nr)) { 88 bcnt = in.dbsz; 89 --cnt; 90 } 91 } else 92 --cnt; 93 continue; 94 } 95 96 if (nr == 0) { 97 if (files_cnt > 1) { 98 --files_cnt; 99 continue; 100 } 101 errx(1, "skip reached end of input"); 102 } 103 104 /* 105 * Input error -- either EOF with no more files, or I/O error. 106 * If noerror not set die. POSIX requires that the warning 107 * message be followed by an I/O display. 108 */ 109 if (ddflags & C_NOERROR) { 110 if (!warned) { 111 warn("%s", in.name); 112 warned = 1; 113 summary(); 114 } 115 continue; 116 } 117 err(1, "%s", in.name); 118 } 119 } 120 121 void 122 pos_out(void) 123 { 124 struct mtop t_op; 125 off_t cnt; 126 ssize_t n; 127 128 /* 129 * If not a tape, try seeking on the file. Seeking on a pipe is 130 * going to fail, but don't protect the user -- they shouldn't 131 * have specified the seek operand. 132 */ 133 if (out.flags & (ISSEEK | ISPIPE)) { 134 errno = 0; 135 if (lseek(out.fd, out.offset * out.dbsz, SEEK_CUR) == -1 && 136 errno != 0) 137 err(1, "%s", out.name); 138 return; 139 } 140 141 /* Don't try to read a really weird amount (like negative). */ 142 if (out.offset < 0) 143 errx(1, "%s: illegal offset", "oseek/seek"); 144 145 /* If no read access, try using mtio. */ 146 if (out.flags & NOREAD) { 147 t_op.mt_op = MTFSR; 148 t_op.mt_count = out.offset; 149 150 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 151 err(1, "%s", out.name); 152 return; 153 } 154 155 /* Read it. */ 156 for (cnt = 0; cnt < out.offset; ++cnt) { 157 if ((n = read(out.fd, out.db, out.dbsz)) > 0) 158 continue; 159 160 if (n == -1) 161 err(1, "%s", out.name); 162 163 /* 164 * If reach EOF, fill with NUL characters; first, back up over 165 * the EOF mark. Note, cnt has not yet been incremented, so 166 * the EOF read does not count as a seek'd block. 167 */ 168 t_op.mt_op = MTBSR; 169 t_op.mt_count = 1; 170 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 171 err(1, "%s", out.name); 172 173 while (cnt++ < out.offset) { 174 n = write(out.fd, out.db, out.dbsz); 175 if (n == -1) 176 err(1, "%s", out.name); 177 if ((size_t)n != out.dbsz) 178 errx(1, "%s: write failure", out.name); 179 } 180 break; 181 } 182 } 183