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 } 71