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open.c revision 1.9 
      1 /*	$NetBSD: open.c,v 1.9 1995/09/19 09:16:52 thorpej 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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  *
     38  *	@(#)open.c	8.1 (Berkeley) 6/11/93
     39  *
     40  *
     41  * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University
     42  * All Rights Reserved.
     43  *
     44  * Author: Alessandro Forin
     45  *
     46  * Permission to use, copy, modify and distribute this software and its
     47  * documentation is hereby granted, provided that both the copyright
     48  * notice and this permission notice appear in all copies of the
     49  * software, derivative works or modified versions, and any portions
     50  * thereof, and that both notices appear in supporting documentation.
     51  *
     52  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     53  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     54  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     55  *
     56  * Carnegie Mellon requests users of this software to return to
     57  *
     58  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     59  *  School of Computer Science
     60  *  Carnegie Mellon University
     61  *  Pittsburgh PA 15213-3890
     62  *
     63  * any improvements or extensions that they make and grant Carnegie the
     64  * rights to redistribute these changes.
     65  */
     66 
     67 #include "stand.h"
     68 struct open_file files[SOPEN_MAX];
     69 
     70 /*
     71  *	File primitives proper
     72  */
     73 
     74 int
     75 open(fname, mode)
     76 	const char *fname;
     77 	int mode;
     78 {
     79 	register struct open_file *f;
     80 	register int fd, i, error;
     81 	char *file;
     82 
     83 	/* find a free file descriptor */
     84 	for (fd = 0, f = files; fd < SOPEN_MAX; fd++, f++)
     85 		if (f->f_flags == 0)
     86 			goto fnd;
     87 	errno = EMFILE;
     88 	return (-1);
     89 fnd:
     90 	/*
     91 	 * Try to open the device.
     92 	 * Convert open mode (0,1,2) to F_READ, F_WRITE.
     93 	 */
     94 	f->f_flags = mode + 1;
     95 	f->f_dev = (struct devsw *)0;
     96 	f->f_ops = (struct fs_ops *)0;
     97 	file = (char *)0;
     98 	error = devopen(f, fname, &file);
     99 	if (error ||
    100 	    (((f->f_flags & F_NODEV) == 0) && f->f_dev == (struct devsw *)0))
    101 		goto err;
    102 
    103 	/* see if we opened a raw device; otherwise, 'file' is the file name. */
    104 	if (file == (char *)0 || *file == '\0') {
    105 		f->f_flags |= F_RAW;
    106 		return (0);
    107 	}
    108 
    109 	/* pass file name to the different filesystem open routines */
    110 	for (i = 0; i < nfsys; i++) {
    111 		/* convert mode (0,1,2) to FREAD, FWRITE. */
    112 		error = (file_system[i].open)(file, f);
    113 		if (error == 0) {
    114 			f->f_ops = &file_system[i];
    115 			return (fd);
    116 		}
    117 	}
    118 	if (!error)
    119 		error = ENOENT;
    120 
    121 err:
    122 	f->f_flags = 0;
    123 	errno = error;
    124 	return (-1);
    125 }
    126 
    127 /*
    128  * Null filesystem
    129  */
    130 int	null_open (char *path, struct open_file *f)
    131 {
    132 	errno  = EIO;
    133 	return -1;
    134 }
    135 
    136 int	null_close(struct open_file *f)
    137 {
    138 	return 0;
    139 }
    140 
    141 ssize_t	null_read (struct open_file *f, void *buf, size_t size, size_t *resid)
    142 {
    143 	errno = EIO;
    144 	return -1;
    145 }
    146 
    147 ssize_t	null_write (struct open_file *f, void *buf, size_t size, size_t *resid)
    148 {
    149 	errno = EIO;
    150 	return -1;
    151 }
    152 
    153 off_t	null_seek (struct open_file *f, off_t offset, int where)
    154 {
    155 	errno = EIO;
    156 	return -1;
    157 }
    158 
    159 int	null_stat (struct open_file *f, struct stat *sb)
    160 {
    161 	errno = EIO;
    162 	return -1;
    163 }
    164 
    165