1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1991, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Keith Muller of the University of California, San Diego and Lance 9 * Visser of Convex Computer Corporation. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #ifndef lint 37 #if 0 38 static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94"; 39 #endif 40 #endif /* not lint */ 41 #include <sys/cdefs.h> 42 __FBSDID("$FreeBSD$"); 43 44 #include <sys/types.h> 45 #include <sys/mtio.h> 46 47 #include <err.h> 48 #include <errno.h> 49 #include <inttypes.h> 50 #include <limits.h> 51 #include <signal.h> 52 #include <unistd.h> 53 54 #include "dd.h" 55 #include "extern.h" 56 57 static off_t 58 seek_offset(IO *io) 59 { 60 off_t n; 61 size_t sz; 62 63 n = io->offset; 64 sz = io->dbsz; 65 66 _Static_assert(sizeof(io->offset) == sizeof(int64_t), "64-bit off_t"); 67 68 /* 69 * If the lseek offset will be negative, verify that this is a special 70 * device file. Some such files (e.g. /dev/kmem) permit "negative" 71 * offsets. 72 * 73 * Bail out if the calculation of a file offset would overflow. 74 */ 75 if ((io->flags & ISCHR) == 0 && (n < 0 || n > OFF_MAX / (ssize_t)sz)) 76 errx(1, "seek offsets cannot be larger than %jd", 77 (intmax_t)OFF_MAX); 78 else if ((io->flags & ISCHR) != 0 && (uint64_t)n > UINT64_MAX / sz) 79 errx(1, "seek offsets cannot be larger than %ju", 80 (uintmax_t)UINT64_MAX); 81 82 return ((off_t)( (uint64_t)n * sz )); 83 } 84 85 /* 86 * Position input/output data streams before starting the copy. Device type 87 * dependent. Seekable devices use lseek, and the rest position by reading. 88 * Seeking past the end of file can cause null blocks to be written to the 89 * output. 90 */ 91 void 92 pos_in(void) 93 { 94 off_t cnt; 95 int warned; 96 ssize_t nr; 97 size_t bcnt; 98 99 /* If known to be seekable, try to seek on it. */ 100 if (in.flags & ISSEEK) { 101 errno = 0; 102 if (lseek(in.fd, seek_offset(&in), SEEK_CUR) == -1 && 103 errno != 0) 104 err(1, "%s", in.name); 105 return; 106 } 107 108 /* Don't try to read a really weird amount (like negative). */ 109 if (in.offset < 0) 110 errx(1, "%s: illegal offset", "iseek/skip"); 111 112 /* 113 * Read the data. If a pipe, read until satisfy the number of bytes 114 * being skipped. No differentiation for reading complete and partial 115 * blocks for other devices. 116 */ 117 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { 118 if ((nr = read(in.fd, in.db, bcnt)) > 0) { 119 if (in.flags & ISPIPE) { 120 if (!(bcnt -= nr)) { 121 bcnt = in.dbsz; 122 --cnt; 123 } 124 } else 125 --cnt; 126 if (need_summary) 127 summary(); 128 if (need_progress) 129 progress(); 130 continue; 131 } 132 133 if (nr == 0) { 134 if (files_cnt > 1) { 135 --files_cnt; 136 continue; 137 } 138 errx(1, "skip reached end of input"); 139 } 140 141 /* 142 * Input error -- either EOF with no more files, or I/O error. 143 * If noerror not set die. POSIX requires that the warning 144 * message be followed by an I/O display. 145 */ 146 if (ddflags & C_NOERROR) { 147 if (!warned) { 148 warn("%s", in.name); 149 warned = 1; 150 summary(); 151 } 152 continue; 153 } 154 err(1, "%s", in.name); 155 } 156 } 157 158 void 159 pos_out(void) 160 { 161 struct mtop t_op; 162 off_t cnt; 163 ssize_t n; 164 165 /* 166 * If not a tape, try seeking on the file. Seeking on a pipe is 167 * going to fail, but don't protect the user -- they shouldn't 168 * have specified the seek operand. 169 */ 170 if (out.flags & (ISSEEK | ISPIPE)) { 171 errno = 0; 172 if (lseek(out.fd, seek_offset(&out), SEEK_CUR) == -1 && 173 errno != 0) 174 err(1, "%s", out.name); 175 return; 176 } 177 178 /* Don't try to read a really weird amount (like negative). */ 179 if (out.offset < 0) 180 errx(1, "%s: illegal offset", "oseek/seek"); 181 182 /* If no read access, try using mtio. */ 183 if (out.flags & NOREAD) { 184 t_op.mt_op = MTFSR; 185 t_op.mt_count = out.offset; 186 187 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 188 err(1, "%s", out.name); 189 return; 190 } 191 192 /* Read it. */ 193 for (cnt = 0; cnt < out.offset; ++cnt) { 194 if ((n = read(out.fd, out.db, out.dbsz)) > 0) 195 continue; 196 197 if (n == -1) 198 err(1, "%s", out.name); 199 200 /* 201 * If reach EOF, fill with NUL characters; first, back up over 202 * the EOF mark. Note, cnt has not yet been incremented, so 203 * the EOF read does not count as a seek'd block. 204 */ 205 t_op.mt_op = MTBSR; 206 t_op.mt_count = 1; 207 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 208 err(1, "%s", out.name); 209 210 while (cnt++ < out.offset) { 211 n = write(out.fd, out.db, out.dbsz); 212 if (n == -1) 213 err(1, "%s", out.name); 214 if (n != out.dbsz) 215 errx(1, "%s: write failure", out.name); 216 } 217 break; 218 } 219 } 220