[unix-history] / usr / src / sys / stand / open.c

/*-
* Copyright (c) 1993 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* %sccs.include.redist.c%
*
*      @(#)open.c      7.1 (Berkeley) %G%
*  
*
* Copyright (c) 1989, 1990, 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Author: Alessandro Forin
* 
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
* 
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
* 
* Carnegie Mellon requests users of this software to return to
* 
*  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
*  School of Computer Science
*  Carnegie Mellon University
*  Pittsburgh PA 15213-3890
* 
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/

#include <stand/stand.h>
#include <stand/ufs.h>

/*
*      File primitives proper
*/

struct fs_ops file_system[] = {
       { ufs_open, ufs_close, ufs_read, ufs_write, ufs_seek, ufs_stat }
};
#define NFSYS   (sizeof(file_system) / sizeof(struct fs_ops))

struct open_file files[SOPEN_MAX];

open(fname, mode)
       char *fname;
       int mode;
{
       register struct open_file *f;
       register int fd, i, error;
       char *file;

       /* find a free file descriptor */
       for (fd = 0, f = files; fd < SOPEN_MAX; fd++, f++)
               if (f->f_flags == 0)
                       goto fnd;
       return (-1);
fnd:
       /*
        * Try to open the device.
        * Convert open mode (0,1,2) to F_READ, F_WRITE.
        */
       f->f_flags = mode + 1;
       f->f_dev = (struct devsw *)0;
       file = (char *)0;
       error = devopen(f, fname, &file);
       if (error || f->f_dev == (struct devsw *)0)
               goto err;

       /* see if we opened a raw device; otherwise, 'file' is the file name. */
       if (file == (char *)0) {
               f->f_flags |= F_RAW;
               return (0);
       }

       /* pass file name to the different filesystem open routines */
       for (i = 0; i < NFSYS; i++) {
               /* convert mode (0,1,2) to FREAD, FWRITE. */
               error = (file_system[i].open)(file, f);
               if (error == 0) {
                       f->f_ops = &file_system[i];
                       return (fd);
               }
       }
       if (!error)
               error = ENOENT;

err:
       errno = error;
       return (-1);
}