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