aboutsummaryrefslogtreecommitdiffstats
path: root/fs/adfs/inode.c
blob: d5250c5aae21e10c560180e1042234d3a4d91f25 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
/*
 *  linux/fs/adfs/inode.c
 *
 *  Copyright (C) 1997-1999 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include "adfs.h"

/*
 * Lookup/Create a block at offset 'block' into 'inode'.  We currently do
 * not support creation of new blocks, so we return -EIO for this case.
 */
static int
adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
	       int create)
{
	if (!create) {
		if (block >= inode->i_blocks)
			goto abort_toobig;

		block = __adfs_block_map(inode->i_sb, inode->i_ino, block);
		if (block)
			map_bh(bh, inode->i_sb, block);
		return 0;
	}
	/* don't support allocation of blocks yet */
	return -EIO;

abort_toobig:
	return 0;
}

static int adfs_writepage(struct page *page, struct writeback_control *wbc)
{
	return block_write_full_page(page, adfs_get_block, wbc);
}

static int adfs_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page, adfs_get_block);
}

static int adfs_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
{
	int ret;

	*pagep = NULL;
	ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
				adfs_get_block,
				&ADFS_I(mapping->host)->mmu_private);
	if (unlikely(ret)) {
		loff_t isize = mapping->host->i_size;
		if (pos + len > isize)
			vmtruncate(mapping->host, isize);
	}

	return ret;
}

static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
{
	return generic_block_bmap(mapping, block, adfs_get_block);
}

static const struct address_space_operations adfs_aops = {
	.readpage	= adfs_readpage,
	.writepage	= adfs_writepage,
	.write_begin	= adfs_write_begin,
	.write_end	= generic_write_end,
	.bmap		= _adfs_bmap
};

/*
 * Convert ADFS attributes and filetype to Linux permission.
 */
static umode_t
adfs_atts2mode(struct super_block *sb, struct inode *inode)
{
	unsigned int attr = ADFS_I(inode)->attr;
	umode_t mode, rmask;
	struct adfs_sb_info *asb = ADFS_SB(sb);

	if (attr & ADFS_NDA_DIRECTORY) {
		mode = S_IRUGO & asb->s_owner_mask;
		return S_IFDIR | S_IXUGO | mode;
	}

	switch (ADFS_I(inode)->filetype) {
	case 0xfc0:	/* LinkFS */
		return S_IFLNK|S_IRWXUGO;

	case 0xfe6:	/* UnixExec */
		rmask = S_IRUGO | S_IXUGO;
		break;

	default:
		rmask = S_IRUGO;
	}

	mode = S_IFREG;

	if (attr & ADFS_NDA_OWNER_READ)
		mode |= rmask & asb->s_owner_mask;

	if (attr & ADFS_NDA_OWNER_WRITE)
		mode |= S_IWUGO & asb->s_owner_mask;

	if (attr & ADFS_NDA_PUBLIC_READ)
		mode |= rmask & asb->s_other_mask;

	if (attr & ADFS_NDA_PUBLIC_WRITE)
		mode |= S_IWUGO & asb->s_other_mask;
	return mode;
}

/*
 * Convert Linux permission to ADFS attribute.  We try to do the reverse
 * of atts2mode, but there is not a 1:1 translation.
 */
static int
adfs_mode2atts(struct super_block *sb, struct inode *inode)
{
	umode_t mode;
	int attr;
	struct adfs_sb_info *asb = ADFS_SB(sb);

	/* FIXME: should we be able to alter a link? */
	if (S_ISLNK(inode->i_mode))
		return ADFS_I(inode)->attr;

	if (S_ISDIR(inode->i_mode))
		attr = ADFS_NDA_DIRECTORY;
	else
		attr = 0;

	mode = inode->i_mode & asb->s_owner_mask;
	if (mode & S_IRUGO)
		attr |= ADFS_NDA_OWNER_READ;
	if (mode & S_IWUGO)
		attr |= ADFS_NDA_OWNER_WRITE;

	mode = inode->i_mode & asb->s_other_mask;
	mode &= ~asb->s_owner_mask;
	if (mode & S_IRUGO)
		attr |= ADFS_NDA_PUBLIC_READ;
	if (mode & S_IWUGO)
		attr |= ADFS_NDA_PUBLIC_WRITE;

	return attr;
}

/*
 * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
 * of time to convert from RISC OS epoch to Unix epoch.
 */
static void
adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
{
	unsigned int high, low;
	/* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
	 * 01 Jan 1900 00:00:00 (RISC OS epoch)
	 */
	static const s64 nsec_unix_epoch_diff_risc_os_epoch =
							2208988800000000000LL;
	s64 nsec;

	if (ADFS_I(inode)->stamped == 0)
		goto cur_time;

	high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
	low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */

	/* convert 40-bit centi-seconds to 32-bit seconds
	 * going via nanoseconds to retain precision
	 */
	nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */

	/* Files dated pre  01 Jan 1970 00:00:00. */
	if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
		goto too_early;

	/* convert from RISC OS to Unix epoch */
	nsec -= nsec_unix_epoch_diff_risc_os_epoch;

	*tv = ns_to_timespec(nsec);
	return;

 cur_time:
	*tv = CURRENT_TIME;
	return;

 too_early:
	tv->tv_sec = tv->tv_nsec = 0;
	return;
}

/*
 * Convert an Unix time to ADFS time.  We only do this if the entry has a
 * time/date stamp already.
 */
static void
adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
{
	unsigned int high, low;

	if (ADFS_I(inode)->stamped) {
		/* convert 32-bit seconds to 40-bit centi-seconds */
		low  = (secs & 255) * 100;
		high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;

		ADFS_I(inode)->loadaddr = (high >> 24) |
				(ADFS_I(inode)->loadaddr & ~0xff);
		ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
	}
}

/*
 * Fill in the inode information from the object information.
 *
 * Note that this is an inode-less filesystem, so we can't use the inode
 * number to reference the metadata on the media.  Instead, we use the
 * inode number to hold the object ID, which in turn will tell us where
 * the data is held.  We also save the parent object ID, and with these
 * two, we can locate the metadata.
 *
 * This does mean that we rely on an objects parent remaining the same at
 * all times - we cannot cope with a cross-directory rename (yet).
 */
struct inode *
adfs_iget(struct super_block *sb, struct object_info *obj)
{
	struct inode *inode;

	inode = new_inode(sb);
	if (!inode)
		goto out;

	inode->i_uid	 = ADFS_SB(sb)->s_uid;
	inode->i_gid	 = ADFS_SB(sb)->s_gid;
	inode->i_ino	 = obj->file_id;
	inode->i_size	 = obj->size;
	inode->i_nlink	 = 2;
	inode->i_blocks	 = (inode->i_size + sb->s_blocksize - 1) >>
			    sb->s_blocksize_bits;

	/*
	 * we need to save the parent directory ID so that
	 * write_inode can update the directory information
	 * for this file.  This will need special handling
	 * for cross-directory renames.
	 */
	ADFS_I(inode)->parent_id = obj->parent_id;
	ADFS_I(inode)->loadaddr  = obj->loadaddr;
	ADFS_I(inode)->execaddr  = obj->execaddr;
	ADFS_I(inode)->attr      = obj->attr;
	ADFS_I(inode)->filetype  = obj->filetype;
	ADFS_I(inode)->stamped   = ((obj->loadaddr & 0xfff00000) == 0xfff00000);

	inode->i_mode	 = adfs_atts2mode(sb, inode);
	adfs_adfs2unix_time(&inode->i_mtime, inode);
	inode->i_atime = inode->i_mtime;
	inode->i_ctime = inode->i_mtime;

	if (S_ISDIR(inode->i_mode)) {
		inode->i_op	= &adfs_dir_inode_operations;
		inode->i_fop	= &adfs_dir_operations;
	} else if (S_ISREG(inode->i_mode)) {
		inode->i_op	= &adfs_file_inode_operations;
		inode->i_fop	= &adfs_file_operations;
		inode->i_mapping->a_ops = &adfs_aops;
		ADFS_I(inode)->mmu_private = inode->i_size;
	}

	insert_inode_hash(inode);

out:
	return inode;
}

/*
 * Validate and convert a changed access mode/time to their ADFS equivalents.
 * adfs_write_inode will actually write the information back to the directory
 * later.
 */
int
adfs_notify_change(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	unsigned int ia_valid = attr->ia_valid;
	int error;
	
	error = inode_change_ok(inode, attr);

	/*
	 * we can't change the UID or GID of any file -
	 * we have a global UID/GID in the superblock
	 */
	if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
	    (ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid))
		error = -EPERM;

	if (error)
		goto out;

	/* XXX: this is missing some actual on-disk truncation.. */
	if (ia_valid & ATTR_SIZE)
		truncate_setsize(inode, attr->ia_size);

	if (ia_valid & ATTR_MTIME) {
		inode->i_mtime = attr->ia_mtime;
		adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
	}
	/*
	 * FIXME: should we make these == to i_mtime since we don't
	 * have the ability to represent them in our filesystem?
	 */
	if (ia_valid & ATTR_ATIME)
		inode->i_atime = attr->ia_atime;
	if (ia_valid & ATTR_CTIME)
		inode->i_ctime = attr->ia_ctime;
	if (ia_valid & ATTR_MODE) {
		ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
		inode->i_mode = adfs_atts2mode(sb, inode);
	}

	/*
	 * FIXME: should we be marking this inode dirty even if
	 * we don't have any metadata to write back?
	 */
	if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
		mark_inode_dirty(inode);
out:
	return error;
}

/*
 * write an existing inode back to the directory, and therefore the disk.
 * The adfs-specific inode data has already been updated by
 * adfs_notify_change()
 */
int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
{
	struct super_block *sb = inode->i_sb;
	struct object_info obj;
	int ret;

	obj.file_id	= inode->i_ino;
	obj.name_len	= 0;
	obj.parent_id	= ADFS_I(inode)->parent_id;
	obj.loadaddr	= ADFS_I(inode)->loadaddr;
	obj.execaddr	= ADFS_I(inode)->execaddr;
	obj.attr	= ADFS_I(inode)->attr;
	obj.size	= inode->i_size;

	ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
	return ret;
}