/* $NetBSD: pread.c,v 1.7.70.1 2019/09/17 19:32:00 martin 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 #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) { size_t rsize; if (!buf) buf = alloc(BUFSIZE); rsize = size; while (rsize > 0) { size_t count; ssize_t 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; }