sys/arch/i386/stand/lib/pread.c

   1 /*      $NetBSD: pread.c,v 1.7 2008/12/14 17:03:43 christos Exp $        */
   2
   3 /*
   4  * Copyright (c) 1996
   5  *      Matthias Drochner.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  *
  27  */
  28
  29 /* read into destination in flat addr space */
  30
  31 #include <lib/libsa/stand.h>
  32
  33 #include "libi386.h"
  34
  35 #ifdef SAVE_MEMORY
  36 #define BUFSIZE (1*1024)
  37 #else
  38 #define BUFSIZE (4*1024)
  39 #endif
  40
  41 static char     *buf;
  42
  43 ssize_t
  44 pread(int fd, void *dest, size_t size)
  45 {
  46         int             rsize;
  47
  48         if (!buf)
  49                 buf = alloc(BUFSIZE);
  50
  51         rsize = size;
  52         while (rsize > 0) {
  53                 int             count, got;
  54
  55                 count = (rsize < BUFSIZE ? rsize : BUFSIZE);
  56
  57                 got = read(fd, buf, count);
  58                 if (got < 0)
  59                         return -1;
  60
  61                 /* put to physical space */
  62                 vpbcopy(buf, dest, got);
  63
  64                 dest += got;
  65                 rsize -= got;
  66                 if (got < count)
  67                         break;  /* EOF */
  68         }
  69         return size - rsize;
  70 }