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open.c revision 1.3 
      1 /*-
      2  * Copyright (c) 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * This code is derived from software contributed to Berkeley by
      6  * The Mach Operating System project at Carnegie-Mellon University.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  *
     36  *	From: @(#)open.c	8.1 (Berkeley) 6/11/93
     37  *
     38  *
     39  * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University
     40  * All Rights Reserved.
     41  *
     42  * Author: Alessandro Forin
     43  *
     44  * Permission to use, copy, modify and distribute this software and its
     45  * documentation is hereby granted, provided that both the copyright
     46  * notice and this permission notice appear in all copies of the
     47  * software, derivative works or modified versions, and any portions
     48  * thereof, and that both notices appear in supporting documentation.
     49  *
     50  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     51  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     52  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     53  *
     54  * Carnegie Mellon requests users of this software to return to
     55  *
     56  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     57  *  School of Computer Science
     58  *  Carnegie Mellon University
     59  *  Pittsburgh PA 15213-3890
     60  *
     61  * any improvements or extensions that they make and grant Carnegie the
     62  * rights to redistribute these changes.
     63  *
     64  * 	$Id: open.c,v 1.3 1994/05/08 16:11:33 brezak Exp $
     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 	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 	file = (char *)0;
     97 	error = devopen(f, fname, &file);
     98 	if (error ||
     99 	    (((f->f_flags & F_NODEV) == 0) && f->f_dev == (struct devsw *)0))
    100 		goto err;
    101 
    102 	/* see if we opened a raw device; otherwise, 'file' is the file name. */
    103 	if (file == (char *)0) {
    104 		f->f_flags |= F_RAW;
    105 		return (0);
    106 	}
    107 
    108 	/* pass file name to the different filesystem open routines */
    109 	for (i = 0; i < nfsys; i++) {
    110 		/* convert mode (0,1,2) to FREAD, FWRITE. */
    111 		error = (file_system[i].open)(file, f);
    112 		if (error == 0) {
    113 			f->f_ops = &file_system[i];
    114 			return (fd);
    115 		}
    116 	}
    117 	if (!error)
    118 		error = ENOENT;
    119 
    120 err:
    121 	errno = error;
    122 	return (-1);
    123 }
    124 
    125 /*
    126  * Null filesystem
    127  */
    128 int	null_open (char *path, struct open_file *f)
    129 {
    130 	errno  = EIO;
    131 	return -1;
    132 }
    133 
    134 int	null_close(struct open_file *f)
    135 {
    136 	return 0;
    137 }
    138 
    139 int	null_read (struct open_file *f, char *buf, u_int size, u_int *resid)
    140 {
    141 	errno = EIO;
    142 	return -1;
    143 }
    144 
    145 int	null_write (struct open_file *f, char *buf, u_int size, u_int *resid)
    146 {
    147 	errno = EIO;
    148 	return -1;
    149 }
    150 
    151 off_t	null_seek (struct open_file *f, off_t offset, int where)
    152 {
    153 	errno = EIO;
    154 	return -1;
    155 }
    156 
    157 int	null_stat (struct open_file *f, struct stat *sb)
    158 {
    159 	errno = EIO;
    160 	return -1;
    161 }
    162 
    163