199767f8919635c4928607450d9e0abb932109ceToomas Soome/* $NetBSD: lseek.c,v 1.4 1997/01/22 00:38:10 cgd Exp $ */
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome/*-
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Copyright (c) 1993
199767f8919635c4928607450d9e0abb932109ceToomas Soome * The Regents of the University of California. All rights reserved.
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * This code is derived from software contributed to Berkeley by
199767f8919635c4928607450d9e0abb932109ceToomas Soome * The Mach Operating System project at Carnegie-Mellon University.
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Redistribution and use in source and binary forms, with or without
199767f8919635c4928607450d9e0abb932109ceToomas Soome * modification, are permitted provided that the following conditions
199767f8919635c4928607450d9e0abb932109ceToomas Soome * are met:
199767f8919635c4928607450d9e0abb932109ceToomas Soome * 1. Redistributions of source code must retain the above copyright
199767f8919635c4928607450d9e0abb932109ceToomas Soome * notice, this list of conditions and the following disclaimer.
199767f8919635c4928607450d9e0abb932109ceToomas Soome * 2. Redistributions in binary form must reproduce the above copyright
199767f8919635c4928607450d9e0abb932109ceToomas Soome * notice, this list of conditions and the following disclaimer in the
199767f8919635c4928607450d9e0abb932109ceToomas Soome * documentation and/or other materials provided with the distribution.
199767f8919635c4928607450d9e0abb932109ceToomas Soome * 4. Neither the name of the University nor the names of its contributors
199767f8919635c4928607450d9e0abb932109ceToomas Soome * may be used to endorse or promote products derived from this software
199767f8919635c4928607450d9e0abb932109ceToomas Soome * without specific prior written permission.
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
199767f8919635c4928607450d9e0abb932109ceToomas Soome * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
199767f8919635c4928607450d9e0abb932109ceToomas Soome * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
199767f8919635c4928607450d9e0abb932109ceToomas Soome * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
199767f8919635c4928607450d9e0abb932109ceToomas Soome * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
199767f8919635c4928607450d9e0abb932109ceToomas Soome * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
199767f8919635c4928607450d9e0abb932109ceToomas Soome * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
199767f8919635c4928607450d9e0abb932109ceToomas Soome * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
199767f8919635c4928607450d9e0abb932109ceToomas Soome * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
199767f8919635c4928607450d9e0abb932109ceToomas Soome * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
199767f8919635c4928607450d9e0abb932109ceToomas Soome * SUCH DAMAGE.
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * @(#)lseek.c 8.1 (Berkeley) 6/11/93
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University
199767f8919635c4928607450d9e0abb932109ceToomas Soome * All Rights Reserved.
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Author: Alessandro Forin
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Permission to use, copy, modify and distribute this software and its
199767f8919635c4928607450d9e0abb932109ceToomas Soome * documentation is hereby granted, provided that both the copyright
199767f8919635c4928607450d9e0abb932109ceToomas Soome * notice and this permission notice appear in all copies of the
199767f8919635c4928607450d9e0abb932109ceToomas Soome * software, derivative works or modified versions, and any portions
199767f8919635c4928607450d9e0abb932109ceToomas Soome * thereof, and that both notices appear in supporting documentation.
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
199767f8919635c4928607450d9e0abb932109ceToomas Soome * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
199767f8919635c4928607450d9e0abb932109ceToomas Soome * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Carnegie Mellon requests users of this software to return to
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
199767f8919635c4928607450d9e0abb932109ceToomas Soome * School of Computer Science
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Carnegie Mellon University
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Pittsburgh PA 15213-3890
199767f8919635c4928607450d9e0abb932109ceToomas Soome *
199767f8919635c4928607450d9e0abb932109ceToomas Soome * any improvements or extensions that they make and grant Carnegie the
199767f8919635c4928607450d9e0abb932109ceToomas Soome * rights to redistribute these changes.
199767f8919635c4928607450d9e0abb932109ceToomas Soome */
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome#include <sys/cdefs.h>
199767f8919635c4928607450d9e0abb932109ceToomas Soome__FBSDID("$FreeBSD$");
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome#include "stand.h"
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soomeoff_t
199767f8919635c4928607450d9e0abb932109ceToomas Soomelseek(int fd, off_t offset, int where)
199767f8919635c4928607450d9e0abb932109ceToomas Soome{
199767f8919635c4928607450d9e0abb932109ceToomas Soome off_t bufpos, filepos, target;
199767f8919635c4928607450d9e0abb932109ceToomas Soome struct open_file *f = &files[fd];
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome if ((unsigned)fd >= SOPEN_MAX || f->f_flags == 0) {
199767f8919635c4928607450d9e0abb932109ceToomas Soome errno = EBADF;
199767f8919635c4928607450d9e0abb932109ceToomas Soome return (-1);
199767f8919635c4928607450d9e0abb932109ceToomas Soome }
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome if (f->f_flags & F_RAW) {
199767f8919635c4928607450d9e0abb932109ceToomas Soome /*
199767f8919635c4928607450d9e0abb932109ceToomas Soome * On RAW devices, update internal offset.
199767f8919635c4928607450d9e0abb932109ceToomas Soome */
199767f8919635c4928607450d9e0abb932109ceToomas Soome switch (where) {
199767f8919635c4928607450d9e0abb932109ceToomas Soome case SEEK_SET:
199767f8919635c4928607450d9e0abb932109ceToomas Soome f->f_offset = offset;
199767f8919635c4928607450d9e0abb932109ceToomas Soome break;
199767f8919635c4928607450d9e0abb932109ceToomas Soome case SEEK_CUR:
199767f8919635c4928607450d9e0abb932109ceToomas Soome f->f_offset += offset;
199767f8919635c4928607450d9e0abb932109ceToomas Soome break;
199767f8919635c4928607450d9e0abb932109ceToomas Soome case SEEK_END:
199767f8919635c4928607450d9e0abb932109ceToomas Soome default:
199767f8919635c4928607450d9e0abb932109ceToomas Soome errno = EOFFSET;
199767f8919635c4928607450d9e0abb932109ceToomas Soome return (-1);
199767f8919635c4928607450d9e0abb932109ceToomas Soome }
199767f8919635c4928607450d9e0abb932109ceToomas Soome return (f->f_offset);
199767f8919635c4928607450d9e0abb932109ceToomas Soome }
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome /*
199767f8919635c4928607450d9e0abb932109ceToomas Soome * If there is some unconsumed data in the readahead buffer and it
199767f8919635c4928607450d9e0abb932109ceToomas Soome * contains the desired offset, simply adjust the buffer offset and
199767f8919635c4928607450d9e0abb932109ceToomas Soome * length. We don't bother with SEEK_END here, since the code to
199767f8919635c4928607450d9e0abb932109ceToomas Soome * handle it would fail in the same cases where the non-readahead
199767f8919635c4928607450d9e0abb932109ceToomas Soome * code fails (namely, for streams which cannot seek backward and whose
199767f8919635c4928607450d9e0abb932109ceToomas Soome * size isn't known in advance).
199767f8919635c4928607450d9e0abb932109ceToomas Soome */
199767f8919635c4928607450d9e0abb932109ceToomas Soome if (f->f_ralen != 0 && where != SEEK_END) {
199767f8919635c4928607450d9e0abb932109ceToomas Soome if ((filepos = (f->f_ops->fo_seek)(f, (off_t)0, SEEK_CUR)) == -1)
199767f8919635c4928607450d9e0abb932109ceToomas Soome return (-1);
199767f8919635c4928607450d9e0abb932109ceToomas Soome bufpos = filepos - f->f_ralen;
199767f8919635c4928607450d9e0abb932109ceToomas Soome switch (where) {
199767f8919635c4928607450d9e0abb932109ceToomas Soome case SEEK_SET:
199767f8919635c4928607450d9e0abb932109ceToomas Soome target = offset;
199767f8919635c4928607450d9e0abb932109ceToomas Soome break;
199767f8919635c4928607450d9e0abb932109ceToomas Soome case SEEK_CUR:
199767f8919635c4928607450d9e0abb932109ceToomas Soome target = bufpos + offset;
199767f8919635c4928607450d9e0abb932109ceToomas Soome break;
199767f8919635c4928607450d9e0abb932109ceToomas Soome default:
199767f8919635c4928607450d9e0abb932109ceToomas Soome errno = EINVAL;
199767f8919635c4928607450d9e0abb932109ceToomas Soome return (-1);
199767f8919635c4928607450d9e0abb932109ceToomas Soome }
199767f8919635c4928607450d9e0abb932109ceToomas Soome if (bufpos <= target && target < filepos) {
199767f8919635c4928607450d9e0abb932109ceToomas Soome f->f_raoffset += target - bufpos;
199767f8919635c4928607450d9e0abb932109ceToomas Soome f->f_ralen -= target - bufpos;
199767f8919635c4928607450d9e0abb932109ceToomas Soome return (target);
199767f8919635c4928607450d9e0abb932109ceToomas Soome }
199767f8919635c4928607450d9e0abb932109ceToomas Soome }
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome /*
199767f8919635c4928607450d9e0abb932109ceToomas Soome * If this is a relative seek, we need to correct the offset for
199767f8919635c4928607450d9e0abb932109ceToomas Soome * bytes that we have already read but the caller doesn't know
199767f8919635c4928607450d9e0abb932109ceToomas Soome * about.
199767f8919635c4928607450d9e0abb932109ceToomas Soome */
199767f8919635c4928607450d9e0abb932109ceToomas Soome if (where == SEEK_CUR)
199767f8919635c4928607450d9e0abb932109ceToomas Soome offset -= f->f_ralen;
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome /*
199767f8919635c4928607450d9e0abb932109ceToomas Soome * Invalidate the readahead buffer.
199767f8919635c4928607450d9e0abb932109ceToomas Soome */
199767f8919635c4928607450d9e0abb932109ceToomas Soome f->f_ralen = 0;
199767f8919635c4928607450d9e0abb932109ceToomas Soome
199767f8919635c4928607450d9e0abb932109ceToomas Soome return (f->f_ops->fo_seek)(f, offset, where);
199767f8919635c4928607450d9e0abb932109ceToomas Soome}