minix/sys/arch/i386/stand/lib/pread.c
2012-02-09 18:48:13 +01:00

70 lines
2 KiB
C

/* $NetBSD: pread.c,v 1.7 2008/12/14 17:03:43 christos Exp $ */
/*
* Copyright (c) 1996
* Matthias Drochner. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/* read into destination in flat addr space */
#include <lib/libsa/stand.h>
#include "libi386.h"
#ifdef SAVE_MEMORY
#define BUFSIZE (1*1024)
#else
#define BUFSIZE (4*1024)
#endif
static char *buf;
ssize_t
pread(int fd, void *dest, size_t size)
{
int rsize;
if (!buf)
buf = alloc(BUFSIZE);
rsize = size;
while (rsize > 0) {
int count, got;
count = (rsize < BUFSIZE ? rsize : BUFSIZE);
got = read(fd, buf, count);
if (got < 0)
return -1;
/* put to physical space */
vpbcopy(buf, dest, got);
dest += got;
rsize -= got;
if (got < count)
break; /* EOF */
}
return size - rsize;
}