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 <signal.h> 49 #include <unistd.h> 50 51 #include "dd.h" 52 #include "extern.h" 53 54 /* 55 * Position input/output data streams before starting the copy. Device type 56 * dependent. Seekable devices use lseek, and the rest position by reading. 57 * Seeking past the end of file can cause null blocks to be written to the 58 * output. 59 */ 60 void 61 pos_in(void) 62 { 63 off_t cnt; 64 int warned; 65 ssize_t nr; 66 size_t bcnt; 67 68 /* If known to be seekable, try to seek on it. */ 69 if (in.flags & ISSEEK) { 70 errno = 0; 71 if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1 && 72 errno != 0) 73 err(1, "%s", in.name); 74 return; 75 } 76 77 /* Don't try to read a really weird amount (like negative). */ 78 if (in.offset < 0) 79 errx(1, "%s: illegal offset", "iseek/skip"); 80 81 /* 82 * Read the data. If a pipe, read until satisfy the number of bytes 83 * being skipped. No differentiation for reading complete and partial 84 * blocks for other devices. 85 */ 86 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { 87 if ((nr = read(in.fd, in.db, bcnt)) > 0) { 88 if (in.flags & ISPIPE) { 89 if (!(bcnt -= nr)) { 90 bcnt = in.dbsz; 91 --cnt; 92 } 93 } else 94 --cnt; 95 if (need_summary) 96 summary(); 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(void) 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