usr.sbin/kgzip/xio.c

   1 /*
   2  * Copyright (c) 1999 Global Technology Associates, Inc.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
  18  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  19  * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  20  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  21  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  22  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  23  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  24  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/usr.sbin/kgzip/xio.c,v 1.2.2.1 2001/07/19 04:42:38 kris Exp $
  27  * $DragonFly: src/usr.sbin/kgzip/xio.c,v 1.2 2003/06/17 04:29:55 dillon Exp $
  28  */
  29
  30 #include <err.h>
  31 #include <string.h>
  32 #include <unistd.h>
  33
  34 #include "kgzip.h"
  35
  36 /*
  37  * Close a file.
  38  */
  39 void
  40 xclose(const struct iodesc *id)
  41 {
  42     if (close(id->fd))
  43         err(1, "%s", id->fname);
  44 }
  45
  46 /*
  47  * Copy bytes from one file to another.
  48  */
  49 void
  50 xcopy(const struct iodesc * idi, const struct iodesc * ido,
  51       size_t nbyte, off_t offset)
  52 {
  53     char buf[8192];
  54     size_t n;
  55
  56     while (nbyte) {
  57         if ((n = sizeof(buf)) > nbyte)
  58             n = nbyte;
  59         if (xread(idi, buf, n, offset) != n)
  60             errx(1, "%s: Short read", idi->fname);
  61         xwrite(ido, buf, n);
  62         nbyte -= n;
  63         offset = -1;
  64     }
  65 }
  66
  67 /*
  68  * Write binary zeroes to a file.
  69  */
  70 void
  71 xzero(const struct iodesc * id, size_t nbyte)
  72 {
  73     char buf[8192];
  74     size_t n;
  75
  76     memset(buf, 0, sizeof(buf));
  77     while (nbyte) {
  78         if ((n = sizeof(buf)) > nbyte)
  79             n = nbyte;
  80         xwrite(id, buf, n);
  81         nbyte -= n;
  82     }
  83 }
  84
  85 /*
  86  * Read from a file.
  87  */
  88 size_t
  89 xread(const struct iodesc * id, void *buf, size_t nbyte, off_t offset)
  90 {
  91     ssize_t n;
  92
  93     if (offset != -1 && lseek(id->fd, offset, SEEK_SET) != offset)
  94         err(1, "%s", id->fname);
  95     if ((n = read(id->fd, buf, nbyte)) == -1)
  96         err(1, "%s", id->fname);
  97     return (size_t)n;
  98 }
  99
 100 /*
 101  * Write to a file.
 102  */
 103 void
 104 xwrite(const struct iodesc * id, const void *buf, size_t nbyte)
 105 {
 106     ssize_t n;
 107
 108     if ((n = write(id->fd, buf, nbyte)) == -1)
 109         err(1, "%s", id->fname);
 110     if ((size_t)n != nbyte)
 111         errx(1, "%s: Short write", id->fname);
 112 }
 113
 114 /*
 115  * Reposition within a file.
 116  */
 117 void
 118 xseek(const struct iodesc *id, off_t offset)
 119 {
 120     if (lseek(id->fd, offset, SEEK_SET) != offset)
 121         err(1, "%s", id->fname);
 122 }