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 #include <sys/types.h> 37 #include <sys/mtio.h> 38 39 #include <err.h> 40 #include <errno.h> 41 #include <inttypes.h> 42 #include <limits.h> 43 #include <signal.h> 44 #include <unistd.h> 45 46 #include "dd.h" 47 #include "extern.h" 48 49 static off_t 50 seek_offset(IO *io) 51 { 52 off_t n; 53 size_t sz; 54 55 n = io->offset; 56 sz = io->dbsz; 57 58 _Static_assert(sizeof(io->offset) == sizeof(int64_t), "64-bit off_t"); 59 60 /* 61 * If the lseek offset will be negative, verify that this is a special 62 * device file. Some such files (e.g. /dev/kmem) permit "negative" 63 * offsets. 64 * 65 * Bail out if the calculation of a file offset would overflow. 66 */ 67 if ((io->flags & ISCHR) == 0 && (n < 0 || n > OFF_MAX / (ssize_t)sz)) 68 errx(1, "seek offsets cannot be larger than %jd", 69 (intmax_t)OFF_MAX); 70 else if ((io->flags & ISCHR) != 0 && (uint64_t)n > UINT64_MAX / sz) 71 errx(1, "seek offsets cannot be larger than %ju", 72 (uintmax_t)UINT64_MAX); 73 74 return ((off_t)( (uint64_t)n * sz )); 75 } 76 77 /* 78 * Position input/output data streams before starting the copy. Device type 79 * dependent. Seekable devices use lseek, and the rest position by reading. 80 * Seeking past the end of file can cause null blocks to be written to the 81 * output. 82 */ 83 void 84 pos_in(void) 85 { 86 off_t cnt; 87 int warned; 88 ssize_t nr; 89 size_t bcnt; 90 91 /* If known to be seekable, try to seek on it. */ 92 if (in.flags & ISSEEK) { 93 errno = 0; 94 if (lseek(in.fd, seek_offset(&in), SEEK_CUR) == -1 && 95 errno != 0) 96 err(1, "%s", in.name); 97 return; 98 } 99 100 /* Don't try to read a really weird amount (like negative). */ 101 if (in.offset < 0) 102 errx(1, "%s: illegal offset", "iseek/skip"); 103 104 /* 105 * Read the data. If a pipe, read until satisfy the number of bytes 106 * being skipped. No differentiation for reading complete and partial 107 * blocks for other devices. 108 */ 109 for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { 110 if ((nr = read(in.fd, in.db, bcnt)) > 0) { 111 if (in.flags & ISPIPE) { 112 if (!(bcnt -= nr)) { 113 bcnt = in.dbsz; 114 --cnt; 115 } 116 } else 117 --cnt; 118 if (need_summary) 119 summary(); 120 if (need_progress) 121 progress(); 122 continue; 123 } 124 125 if (nr == 0) { 126 if (files_cnt > 1) { 127 --files_cnt; 128 continue; 129 } 130 errx(1, "skip reached end of input"); 131 } 132 133 /* 134 * Input error -- either EOF with no more files, or I/O error. 135 * If noerror not set die. POSIX requires that the warning 136 * message be followed by an I/O display. 137 */ 138 if (ddflags & C_NOERROR) { 139 if (!warned) { 140 warn("%s", in.name); 141 warned = 1; 142 summary(); 143 } 144 continue; 145 } 146 err(1, "%s", in.name); 147 } 148 } 149 150 void 151 pos_out(void) 152 { 153 struct mtop t_op; 154 off_t cnt; 155 ssize_t n; 156 157 /* 158 * If not a tape, try seeking on the file. Seeking on a pipe is 159 * going to fail, but don't protect the user -- they shouldn't 160 * have specified the seek operand. 161 */ 162 if (out.flags & (ISSEEK | ISPIPE)) { 163 errno = 0; 164 if (lseek(out.fd, seek_offset(&out), SEEK_CUR) == -1 && 165 errno != 0) 166 err(1, "%s", out.name); 167 return; 168 } 169 170 /* Don't try to read a really weird amount (like negative). */ 171 if (out.offset < 0) 172 errx(1, "%s: illegal offset", "oseek/seek"); 173 174 /* If no read access, try using mtio. */ 175 if (out.flags & NOREAD) { 176 t_op.mt_op = MTFSR; 177 t_op.mt_count = out.offset; 178 179 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 180 err(1, "%s", out.name); 181 return; 182 } 183 184 /* Read it. */ 185 for (cnt = 0; cnt < out.offset; ++cnt) { 186 before_io(); 187 n = read(out.fd, out.db, out.dbsz); 188 after_io(); 189 if (n > 0) 190 continue; 191 if (n == -1) 192 err(1, "%s", out.name); 193 194 /* 195 * If reach EOF, fill with NUL characters; first, back up over 196 * the EOF mark. Note, cnt has not yet been incremented, so 197 * the EOF read does not count as a seek'd block. 198 */ 199 t_op.mt_op = MTBSR; 200 t_op.mt_count = 1; 201 if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 202 err(1, "%s", out.name); 203 204 while (cnt++ < out.offset) { 205 before_io(); 206 n = write(out.fd, out.db, out.dbsz); 207 after_io(); 208 if (n == -1) 209 err(1, "%s", out.name); 210 if (n != out.dbsz) 211 errx(1, "%s: write failure", out.name); 212 } 213 break; 214 } 215 } 216