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rawfs.c revision 1.2 
      1 /*	$NetBSD: rawfs.c,v 1.2 2001/07/07 09:06:43 scw Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1995 Gordon W. Ross
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. The name of the author may not be used to endorse or promote products
     16  *    derived from this software without specific prior written permission.
     17  * 4. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *      This product includes software developed by Gordon W. Ross
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 /*
     34  * Raw file system - for stream devices like tapes.
     35  * No random access, only sequential read allowed.
     36  * This exists only to allow upper level code to be
     37  * shielded from the fact that the device must be
     38  * read only with whole block position and size.
     39  */
     40 
     41 #include <sys/param.h>
     42 #include <stand.h>
     43 #include <rawfs.h>
     44 
     45 extern int debug;
     46 
     47 #define	RAWFS_BSIZE	512
     48 
     49 /*
     50  * In-core open file.
     51  */
     52 struct file {
     53 	daddr_t		fs_nextblk;	/* block number to read next */
     54 	int		fs_len;		/* amount left in f_buf */
     55 	char *		fs_ptr;		/* read pointer into f_buf */
     56 	char		fs_buf[RAWFS_BSIZE];
     57 };
     58 
     59 static int
     60 rawfs_get_block __P((struct open_file *));
     61 
     62 int	rawfs_open(path, f)
     63 	char *path;
     64 	struct open_file *f;
     65 {
     66 	struct file *fs;
     67 
     68 	/*
     69 	 * The actual PROM driver has already been opened.
     70 	 * Just allocate the I/O buffer, etc.
     71 	 */
     72 	fs = alloc(sizeof(struct file));
     73 	fs->fs_nextblk = 0;
     74 	fs->fs_len = 0;
     75 	fs->fs_ptr = fs->fs_buf;
     76 
     77 	f->f_fsdata = fs;
     78 	return (0);
     79 }
     80 
     81 int	rawfs_close(f)
     82 	struct open_file *f;
     83 {
     84 	struct file *fs;
     85 
     86 	fs = (struct file *) f->f_fsdata;
     87 	f->f_fsdata = (void *)0;
     88 
     89 	if (fs != (struct file *)0)
     90 		free(fs, sizeof(*fs));
     91 
     92 	return (0);
     93 }
     94 
     95 int	rawfs_read(f, start, size, resid)
     96 	struct open_file *f;
     97 	void *start;
     98 	u_int size;
     99 	u_int *resid;
    100 {
    101 	struct file *fs = (struct file *)f->f_fsdata;
    102 	char *addr = start;
    103 	int error = 0;
    104 	size_t csize;
    105 
    106 	while (size != 0) {
    107 
    108 		if (fs->fs_len == 0)
    109 			if ((error = rawfs_get_block(f)) != 0)
    110 				break;
    111 
    112 		if (fs->fs_len <= 0)
    113 			break;	/* EOF */
    114 
    115 		csize = size;
    116 		if (csize > fs->fs_len)
    117 			csize = fs->fs_len;
    118 
    119 		memcpy(addr, fs->fs_ptr, csize);
    120 		fs->fs_ptr += csize;
    121 		fs->fs_len -= csize;
    122 		addr += csize;
    123 		size -= csize;
    124 	}
    125 	if (resid)
    126 		*resid = size;
    127 	return (error);
    128 }
    129 
    130 int	rawfs_write(f, start, size, resid)
    131 	struct open_file *f;
    132 	void *start;
    133 	size_t size;
    134 	size_t *resid;	/* out */
    135 {
    136 	return (EROFS);
    137 }
    138 
    139 off_t	rawfs_seek(f, offset, where)
    140 	struct open_file *f;
    141 	off_t offset;
    142 	int where;
    143 {
    144 	return (EFTYPE);
    145 }
    146 
    147 int	rawfs_stat(f, sb)
    148 	struct open_file *f;
    149 	struct stat *sb;
    150 {
    151 	return (EFTYPE);
    152 }
    153 
    154 
    155 /*
    156  * Read a block from the underlying stream device
    157  * (In our case, a tape drive.)
    158  */
    159 static int
    160 rawfs_get_block(f)
    161 	struct open_file *f;
    162 {
    163 	struct file *fs;
    164 	int error, len;
    165 
    166 	fs = (struct file *)f->f_fsdata;
    167 	fs->fs_ptr = fs->fs_buf;
    168 
    169 	twiddle();
    170 	error = f->f_dev->dv_strategy(f->f_devdata, F_READ,
    171 		fs->fs_nextblk, RAWFS_BSIZE,	fs->fs_buf, &len);
    172 
    173 	if (!error) {
    174 		fs->fs_len = len;
    175 		fs->fs_nextblk += (RAWFS_BSIZE / DEV_BSIZE);
    176 	}
    177 
    178 	return (error);
    179 }
    180 
    181