bin/dd/position.c

   1 /*      $NetBSD: position.c,v 1.16 2003/09/14 19:20:20 jschauma Exp $   */
   2
   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/cdefs.h>
  37 #ifndef lint
  38 #if 0
  39 static char sccsid[] = "@(#)position.c  8.3 (Berkeley) 4/2/94";
  40 #else
  41 __RCSID("$NetBSD: position.c,v 1.16 2003/09/14 19:20:20 jschauma Exp $");
  42 #endif
  43 #endif /* not lint */
  44
  45 #include <sys/types.h>
  46 #include <sys/stat.h>
  47 #include <sys/ioctl.h>
  48 #include <sys/mtio.h>
  49 #include <sys/time.h>
  50
  51 #include <err.h>
  52 #include <errno.h>
  53 #include <stdlib.h>
  54 #include <string.h>
  55 #include <unistd.h>
  56
  57 #include "dd.h"
  58 #include "extern.h"
  59
  60 /*
  61  * Position input/output data streams before starting the copy.  Device type
  62  * dependent.  Seekable devices use lseek, and the rest position by reading.
  63  * Seeking past the end of file can cause null blocks to be written to the
  64  * output.
  65  */
  66 void
  67 pos_in(void)
  68 {
  69         int bcnt, cnt, nr, warned;
  70
  71         /* If not a pipe or tape device, try to seek on it. */
  72         if (!(in.flags & (ISPIPE|ISTAPE))) {
  73                 if (lseek(in.fd,
  74                     (off_t)in.offset * (off_t)in.dbsz, SEEK_CUR) == -1) {
  75                         err(EXIT_FAILURE, "%s", in.name);
  76                         /* NOTREACHED */
  77                 }
  78                 return;
  79                 /* NOTREACHED */
  80         }
  81
  82         /*
  83          * Read the data.  If a pipe, read until satisfy the number of bytes
  84          * being skipped.  No differentiation for reading complete and partial
  85          * blocks for other devices.
  86          */
  87         for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
  88                 if ((nr = read(in.fd, in.db, bcnt)) > 0) {
  89                         if (in.flags & ISPIPE) {
  90                                 if (!(bcnt -= nr)) {
  91                                         bcnt = in.dbsz;
  92                                         --cnt;
  93                                 }
  94                         } else
  95                                 --cnt;
  96                         continue;
  97                 }
  98
  99                 if (nr == 0) {
 100                         if (files_cnt > 1) {
 101                                 --files_cnt;
 102                                 continue;
 103                         }
 104                         errx(EXIT_FAILURE, "skip reached end of input");
 105                         /* NOTREACHED */
 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
 116                                 warn("%s", in.name);
 117                                 warned = 1;
 118                                 summary();
 119                         }
 120                         continue;
 121                 }
 122                 err(EXIT_FAILURE, "%s", in.name);
 123                 /* NOTREACHED */
 124         }
 125 }
 126
 127 void
 128 pos_out(void)
 129 {
 130         struct mtop t_op;
 131         int n;
 132         uint64_t cnt;
 133
 134         /*
 135          * If not a tape, try seeking on the file.  Seeking on a pipe is
 136          * going to fail, but don't protect the user -- they shouldn't
 137          * have specified the seek operand.
 138          */
 139         if (!(out.flags & ISTAPE)) {
 140                 if (lseek(out.fd,
 141                     (off_t)out.offset * (off_t)out.dbsz, SEEK_SET) == -1)
 142                         err(EXIT_FAILURE, "%s", out.name);
 143                         /* NOTREACHED */
 144                 return;
 145         }
 146
 147         /* If no read access, try using mtio. */
 148         if (out.flags & NOREAD) {
 149                 t_op.mt_op = MTFSR;
 150                 t_op.mt_count = out.offset;
 151
 152                 if (ioctl(out.fd, MTIOCTOP, &t_op) < 0)
 153                         err(EXIT_FAILURE, "%s", out.name);
 154                         /* NOTREACHED */
 155                 return;
 156         }
 157
 158         /* Read it. */
 159         for (cnt = 0; cnt < out.offset; ++cnt) {
 160                 if ((n = read(out.fd, out.db, out.dbsz)) > 0)
 161                         continue;
 162
 163                 if (n < 0)
 164                         err(EXIT_FAILURE, "%s", out.name);
 165                         /* NOTREACHED */
 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(EXIT_FAILURE, "%s", out.name);
 176                         /* NOTREACHED */
 177
 178                 while (cnt++ < out.offset)
 179                         if ((uint64_t)(n = bwrite(out.fd, out.db, out.dbsz)) != out.dbsz)
 180                                 err(EXIT_FAILURE, "%s", out.name);
 181                                 /* NOTREACHED */
 182                 break;
 183         }
 184 }