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 "$FreeBSD$"; 44 #endif /* not lint */ 45 46 #include <sys/types.h> 47 #include <sys/mtio.h> 48 49 #include <err.h> 50 #include <unistd.h> 51 52 #include "dd.h" 53 #include "extern.h" 54 55 /* 56 * Position input/output data streams before starting the copy. Device type 57 * dependent. Seekable devices use lseek, and the rest position by reading. 58 * Seeking past the end of file can cause null blocks to be written to the 59 * output. 60 */ 61 void 62 pos_in() 63 { 64 int bcnt, warned; 65 ssize_t nr; 66 off_t cnt; 67 68 /* If not a character, pipe or tape device, try to seek on it. */ 69 if (!(in.flags & (ISCHR|ISPIPE|ISTAPE)) || in.flags & ISDISK) { 70 if (lseek(in.fd, 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 off_t cnt; 122 ssize_t n; 123 124 /* If not a character, pipe or tape device, try to seek on it. */ 125 if (!(out.flags & (ISCHR|ISPIPE|ISTAPE)) || out.flags & ISDISK) { 126 if (lseek(out.fd, out.offset * out.dbsz, SEEK_SET) == -1) 127 err(1, "%s", out.name); 128 return; 129 } 130 131 /* If no read access, try using mtio. */ 132 if (out.flags & NOREAD) { 133 t_op.mt_op = MTFSR; 134 t_op.mt_count = out.offset; 135 136 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 137 err(1, "%s", out.name); 138 return; 139 } 140 141 /* Read it. */ 142 for (cnt = 0; cnt < out.offset; ++cnt) { 143 if ((n = read(out.fd, out.db, out.dbsz)) > 0) 144 continue; 145 146 if (n == -1) 147 err(1, "%s", out.name); 148 149 /* 150 * If reach EOF, fill with NUL characters; first, back up over 151 * the EOF mark. Note, cnt has not yet been incremented, so 152 * the EOF read does not count as a seek'd block. 153 */ 154 t_op.mt_op = MTBSR; 155 t_op.mt_count = 1; 156 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 157 err(1, "%s", out.name); 158 159 while (cnt++ < out.offset) 160 if ((n = write(out.fd, out.db, out.dbsz)) != out.dbsz) 161 err(1, "%s", out.name); 162 break; 163 } 164 } 165