OpenSolaris_b135/lib/libc/port/stdio/fseek.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*	Copyright (c) 1988 AT&T	*/
/*	  All Rights Reserved  	*/

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*
 * Seek for standard library.  Coordinates with buffering.
 */

#pragma weak _fseek = fseek

#include "lint.h"
#include "file64.h"
#include "mtlib.h"
#include <stdio.h>
#include <errno.h>
#include <thread.h>
#include <synch.h>
#include <unistd.h>
#include <sys/types.h>
#include "stdiom.h"

int
fseek(FILE *iop, long offset, int ptrname)
{
	off_t	p;
	rmutex_t *lk;

	FLOCKFILE(lk, iop);
	iop->_flag &= ~_IOEOF;

	if (!(iop->_flag & _IOREAD) && !(iop->_flag & (_IOWRT | _IORW))) {
		errno = EBADF;
		FUNLOCKFILE(lk);
		return (-1);
	}

	if (iop->_flag & _IOREAD) {
		if (ptrname == 1 && iop->_base && !(iop->_flag&_IONBF)) {
			offset -= iop->_cnt;
		}
	} else if (iop->_flag & (_IOWRT | _IORW)) {
		if (_fflush_u(iop) == EOF) {
			FUNLOCKFILE(lk);
			return (-1);
		}
	}
	iop->_cnt = 0;
	iop->_ptr = iop->_base;
	if (iop->_flag & _IORW) {
		iop->_flag &= ~(_IOREAD | _IOWRT);
	}
	p = lseek(FILENO(iop), (off_t)offset, ptrname);
	FUNLOCKFILE(lk);
	return ((p == (off_t)-1) ? -1: 0);
}