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 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #ifndef lint 35 #if 0 36 static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94"; 37 #endif 38 #endif /* not lint */ 39 #include <sys/cdefs.h> 40 __FBSDID("$FreeBSD$"); 41 42 #include <sys/types.h> 43 #include <sys/mtio.h> 44 45 #include <err.h> 46 #include <errno.h> 47 #include <inttypes.h> 48 #include <unistd.h> 49 50 #include "dd.h" 51 #include "extern.h" 52 53 /* 54 * Position input/output data streams before starting the copy. Device type 55 * dependent. Seekable devices use lseek, and the rest position by reading. 56 * Seeking past the end of file can cause null blocks to be written to the 57 * output. 58 */ 59 void 60 pos_in(void) 61 { 62 off_t cnt; 63 int warned; 64 ssize_t nr; 65 size_t bcnt; 66 67 /* If known to be seekable, try to seek on it. */ 68 if (in.flags & ISSEEK) { 69 errno = 0; 70 if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1 && 71 errno != 0) 72 err(1, "%s", in.name); 73 return; 74 } 75 76 /* Don't try to read a really weird amount (like negative). */ 77 if (in.offset < 0) 78 errx(1, "%s: illegal offset", "iseek/skip"); 79 80 /* 81 * Read the data. If a pipe, read until satisfy the number of bytes 82 * being skipped. No differentiation for reading complete and partial 83 * blocks for other devices. 84 */ 85 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { 86 if ((nr = read(in.fd, in.db, bcnt)) > 0) { 87 if (in.flags & ISPIPE) { 88 if (!(bcnt -= nr)) { 89 bcnt = in.dbsz; 90 --cnt; 91 } 92 } else 93 --cnt; 94 continue; 95 } 96 97 if (nr == 0) { 98 if (files_cnt > 1) { 99 --files_cnt; 100 continue; 101 } 102 errx(1, "skip reached end of input"); 103 } 104 105 /* 106 * Input error -- either EOF with no more files, or I/O error. 107 * If noerror not set die. POSIX requires that the warning 108 * message be followed by an I/O display. 109 */ 110 if (ddflags & C_NOERROR) { 111 if (!warned) { 112 warn("%s", in.name); 113 warned = 1; 114 summary(); 115 } 116 continue; 117 } 118 err(1, "%s", in.name); 119 } 120 } 121 122 void 123 pos_out(void) 124 { 125 struct mtop t_op; 126 off_t cnt; 127 ssize_t n; 128 129 /* 130 * If not a tape, try seeking on the file. Seeking on a pipe is 131 * going to fail, but don't protect the user -- they shouldn't 132 * have specified the seek operand. 133 */ 134 if (out.flags & (ISSEEK | ISPIPE)) { 135 errno = 0; 136 if (lseek(out.fd, out.offset * out.dbsz, SEEK_CUR) == -1 && 137 errno != 0) 138 err(1, "%s", out.name); 139 return; 140 } 141 142 /* Don't try to read a really weird amount (like negative). */ 143 if (out.offset < 0) 144 errx(1, "%s: illegal offset", "oseek/seek"); 145 146 /* If no read access, try using mtio. */ 147 if (out.flags & NOREAD) { 148 t_op.mt_op = MTFSR; 149 t_op.mt_count = out.offset; 150 151 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 152 err(1, "%s", out.name); 153 return; 154 } 155 156 /* Read it. */ 157 for (cnt = 0; cnt < out.offset; ++cnt) { 158 if ((n = read(out.fd, out.db, out.dbsz)) > 0) 159 continue; 160 161 if (n == -1) 162 err(1, "%s", out.name); 163 164 /* 165 * If reach EOF, fill with NUL characters; first, back up over 166 * the EOF mark. Note, cnt has not yet been incremented, so 167 * the EOF read does not count as a seek'd block. 168 */ 169 t_op.mt_op = MTBSR; 170 t_op.mt_count = 1; 171 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 172 err(1, "%s", out.name); 173 174 while (cnt++ < out.offset) { 175 n = write(out.fd, out.db, out.dbsz); 176 if (n == -1) 177 err(1, "%s", out.name); 178 if ((size_t)n != out.dbsz) 179 errx(1, "%s: write failure", out.name); 180 } 181 break; 182 } 183 } 184