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 #ifndef lint 39 #if 0 40 static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94"; 41 #endif 42 static const char rcsid[] = 43 "$FreeBSD: src/bin/dd/position.c,v 1.17.2.2 2001/01/23 14:23:55 asmodai Exp $"; 44 #endif /* not lint */ 45 46 #include <sys/types.h> 47 #include <sys/mtio.h> 48 49 #include <err.h> 50 #include <errno.h> 51 #include <unistd.h> 52 53 #include "dd.h" 54 #include "extern.h" 55 56 /* 57 * Position input/output data streams before starting the copy. Device type 58 * dependent. Seekable devices use lseek, and the rest position by reading. 59 * Seeking past the end of file can cause null blocks to be written to the 60 * output. 61 */ 62 void 63 pos_in() 64 { 65 off_t cnt; 66 int warned; 67 ssize_t nr; 68 size_t bcnt; 69 70 /* If known to be seekable, try to seek on it. */ 71 if (in.flags & ISSEEK) { 72 errno = 0; 73 if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1 && 74 errno != 0) 75 err(1, "%s", in.name); 76 return; 77 } 78 79 /* Don't try to read a really weird amount (like negative). */ 80 if (in.offset < 0) 81 errx(1, "%s: illegal offset", "iseek/skip"); 82 83 /* 84 * Read the data. If a pipe, read until satisfy the number of bytes 85 * being skipped. No differentiation for reading complete and partial 86 * blocks for other devices. 87 */ 88 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { 89 if ((nr = read(in.fd, in.db, bcnt)) > 0) { 90 if (in.flags & ISPIPE) { 91 if (!(bcnt -= nr)) { 92 bcnt = in.dbsz; 93 --cnt; 94 } 95 } else 96 --cnt; 97 continue; 98 } 99 100 if (nr == 0) { 101 if (files_cnt > 1) { 102 --files_cnt; 103 continue; 104 } 105 errx(1, "skip reached end of input"); 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 warn("%s", in.name); 116 warned = 1; 117 summary(); 118 } 119 continue; 120 } 121 err(1, "%s", in.name); 122 } 123 } 124 125 void 126 pos_out() 127 { 128 struct mtop t_op; 129 off_t cnt; 130 ssize_t n; 131 132 /* 133 * If not a tape, try seeking on the file. Seeking on a pipe is 134 * going to fail, but don't protect the user -- they shouldn't 135 * have specified the seek operand. 136 */ 137 if (out.flags & (ISSEEK | ISPIPE)) { 138 errno = 0; 139 if (lseek(out.fd, out.offset * out.dbsz, SEEK_CUR) == -1 && 140 errno != 0) 141 err(1, "%s", out.name); 142 return; 143 } 144 145 /* Don't try to read a really weird amount (like negative). */ 146 if (out.offset < 0) 147 errx(1, "%s: illegal offset", "oseek/seek"); 148 149 /* If no read access, try using mtio. */ 150 if (out.flags & NOREAD) { 151 t_op.mt_op = MTFSR; 152 t_op.mt_count = out.offset; 153 154 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 155 err(1, "%s", out.name); 156 return; 157 } 158 159 /* Read it. */ 160 for (cnt = 0; cnt < out.offset; ++cnt) { 161 if ((n = read(out.fd, out.db, out.dbsz)) > 0) 162 continue; 163 164 if (n == -1) 165 err(1, "%s", out.name); 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 (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 175 err(1, "%s", out.name); 176 177 while (cnt++ < out.offset) { 178 n = write(out.fd, out.db, out.dbsz); 179 if (n == -1) 180 err(1, "%s", out.name); 181 if ((size_t)n != out.dbsz) 182 errx(1, "%s: write failure", out.name); 183 } 184 break; 185 } 186 } 187