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lseek.c revision 1.8 
      1 /*	$NetBSD: lseek.c,v 1.8 2005/02/26 22:58:56 perry Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * The Mach Operating System project at Carnegie-Mellon University.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  *
     34  *	@(#)lseek.c	8.1 (Berkeley) 6/11/93
     35  *
     36  *
     37  * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University
     38  * All Rights Reserved.
     39  *
     40  * Author: Alessandro Forin
     41  *
     42  * Permission to use, copy, modify and distribute this software and its
     43  * documentation is hereby granted, provided that both the copyright
     44  * notice and this permission notice appear in all copies of the
     45  * software, derivative works or modified versions, and any portions
     46  * thereof, and that both notices appear in supporting documentation.
     47  *
     48  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     49  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     50  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     51  *
     52  * Carnegie Mellon requests users of this software to return to
     53  *
     54  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     55  *  School of Computer Science
     56  *  Carnegie Mellon University
     57  *  Pittsburgh PA 15213-3890
     58  *
     59  * any improvements or extensions that they make and grant Carnegie the
     60  * rights to redistribute these changes.
     61  */
     62 
     63 #include "stand.h"
     64 
     65 off_t
     66 #ifndef __INTERNAL_LIBSA_CREAD
     67 lseek(fd, offset, where)
     68 #else
     69 olseek(fd, offset, where)
     70 #endif
     71 	int fd;
     72 	off_t offset;
     73 	int where;
     74 {
     75 	struct open_file *f = &files[fd];
     76 
     77 #if !defined(LIBSA_NO_FD_CHECKING)
     78 	if ((unsigned)fd >= SOPEN_MAX || f->f_flags == 0) {
     79 		errno = EBADF;
     80 		return (-1);
     81 	}
     82 #endif
     83 
     84 #if !defined(LIBSA_NO_RAW_ACCESS)
     85 	if (f->f_flags & F_RAW) {
     86 		/*
     87 		 * On RAW devices, update internal offset.
     88 		 */
     89 		switch (where) {
     90 		case SEEK_SET:
     91 			f->f_offset = offset;
     92 			break;
     93 		case SEEK_CUR:
     94 			f->f_offset += offset;
     95 			break;
     96 		case SEEK_END:
     97 		default:
     98 			errno = EOFFSET;
     99 			return (-1);
    100 		}
    101 		return (f->f_offset);
    102 	}
    103 #endif
    104 
    105 	return FS_SEEK(f->f_ops)(f, offset, where);
    106 }
    107