1/*
2 * $NetBSD: pread.c,v 1.2 1997/03/22 01:48:38 thorpej Exp $
3 */
4
5/*-
6 * Copyright (c) 1996
7 *	Matthias Drochner.  All rights reserved.
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 for the NetBSD Project
20 *	by Matthias Drochner.
21 * 4. The name of the author may not be used to endorse or promote products
22 *    derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36/* read into destination in flat addr space */
37
38#include <stand.h>
39
40#include "libi386.h"
41
42#ifdef SAVE_MEMORY
43#define BUFSIZE (1*1024)
44#else
45#define BUFSIZE (4*1024)
46#endif
47
48static char     buf[BUFSIZE];
49
50int
51pread(fd, dest, size)
52	int             fd;
53	vm_offset_t         dest;
54	int             size;
55{
56	int             rsize;
57
58	rsize = size;
59	while (rsize > 0) {
60		int             count, got;
61
62		count = (rsize < BUFSIZE ? rsize : BUFSIZE);
63
64		got = read(fd, buf, count);
65		if (got < 0)
66			return (-1);
67
68		/* put to physical space */
69		vpbcopy(buf, dest, got);
70
71		dest += got;
72		rsize -= got;
73		if (got < count)
74			break;	/* EOF */
75	}
76	return (size - rsize);
77}
78