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