summaryrefslogtreecommitdiffstats
path: root/fs/adfs/dir_f.c
blob: bbfc862592721fe4b79d8f60c36a13386f6c1269 (plain)
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
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
/*
 *  linux/fs/adfs/dir_f.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.
 *
 *  E and F format directory handling
 */
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/adfs_fs.h>
#include <linux/time.h>
#include <linux/stat.h>
#include <linux/spinlock.h>
#include <linux/buffer_head.h>
#include <linux/string.h>

#include "adfs.h"
#include "dir_f.h"

static void adfs_f_free(struct adfs_dir *dir);

/*
 * Read an (unaligned) value of length 1..4 bytes
 */
static inline unsigned int adfs_readval(unsigned char *p, int len)
{
	unsigned int val = 0;

	switch (len) {
	case 4:		val |= p[3] << 24;
	case 3:		val |= p[2] << 16;
	case 2:		val |= p[1] << 8;
	default:	val |= p[0];
	}
	return val;
}

static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
{
	switch (len) {
	case 4:		p[3] = val >> 24;
	case 3:		p[2] = val >> 16;
	case 2:		p[1] = val >> 8;
	default:	p[0] = val;
	}
}

static inline int adfs_readname(char *buf, char *ptr, int maxlen)
{
	char *old_buf = buf;

	while (*ptr >= ' ' && maxlen--) {
		if (*ptr == '/')
			*buf++ = '.';
		else
			*buf++ = *ptr;
		ptr++;
	}
	*buf = '\0';

	return buf - old_buf;
}

#define ror13(v) ((v >> 13) | (v << 19))

#define dir_u8(idx)				\
	({ int _buf = idx >> blocksize_bits;	\
	   int _off = idx - (_buf << blocksize_bits);\
	  *(u8 *)(bh[_buf]->b_data + _off);	\
	})

#define dir_u32(idx)				\
	({ int _buf = idx >> blocksize_bits;	\
	   int _off = idx - (_buf << blocksize_bits);\
	  *(__le32 *)(bh[_buf]->b_data + _off);	\
	})

#define bufoff(_bh,_idx)			\
	({ int _buf = _idx >> blocksize_bits;	\
	   int _off = _idx - (_buf << blocksize_bits);\
	  (u8 *)(_bh[_buf]->b_data + _off);	\
	})

/*
 * There are some algorithms that are nice in
 * assembler, but a bitch in C...  This is one
 * of them.
 */
static u8
adfs_dir_checkbyte(const struct adfs_dir *dir)
{
	struct buffer_head * const *bh = dir->bh;
	const int blocksize_bits = dir->sb->s_blocksize_bits;
	union { __le32 *ptr32; u8 *ptr8; } ptr, end;
	u32 dircheck = 0;
	int last = 5 - 26;
	int i = 0;

	/*
	 * Accumulate each word up to the last whole
	 * word of the last directory entry.  This
	 * can spread across several buffer heads.
	 */
	do {
		last += 26;
		do {
			dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);

			i += sizeof(u32);
		} while (i < (last & ~3));
	} while (dir_u8(last) != 0);

	/*
	 * Accumulate the last few bytes.  These
	 * bytes will be within the same bh.
	 */
	if (i != last) {
		ptr.ptr8 = bufoff(bh, i);
		end.ptr8 = ptr.ptr8 + last - i;

		do
			dircheck = *ptr.ptr8++ ^ ror13(dircheck);
		while (ptr.ptr8 < end.ptr8);
	}

	/*
	 * The directory tail is in the final bh
	 * Note that contary to the RISC OS PRMs,
	 * the first few bytes are NOT included
	 * in the check.  All bytes are in the
	 * same bh.
	 */
	ptr.ptr8 = bufoff(bh, 2008);
	end.ptr8 = ptr.ptr8 + 36;

	do {
		__le32 v = *ptr.ptr32++;
		dircheck = le32_to_cpu(v) ^ ror13(dircheck);
	} while (ptr.ptr32 < end.ptr32);

	return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
}

/*
 * Read and check that a directory is valid
 */
static int
adfs_dir_read(struct super_block *sb, unsigned long object_id,
	      unsigned int size, struct adfs_dir *dir)
{
	const unsigned int blocksize_bits = sb->s_blocksize_bits;
	int blk = 0;

	/*
	 * Directories which are not a multiple of 2048 bytes
	 * are considered bad v2 [3.6]
	 */
	if (size & 2047)
		goto bad_dir;

	size >>= blocksize_bits;

	dir->nr_buffers = 0;
	dir->sb = sb;

	for (blk = 0; blk < size; blk++) {
		int phys;

		phys = __adfs_block_map(sb, object_id, blk);
		if (!phys) {
			adfs_error(sb, "dir object %lX has a hole at offset %d",
				   object_id, blk);
			goto release_buffers;
		}

		dir->bh[blk] = sb_bread(sb, phys);
		if (!dir->bh[blk])
			goto release_buffers;
	}

	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));

	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
		goto bad_dir;

	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
	    memcmp(&dir->dirhead.startname, "Hugo", 4))
		goto bad_dir;

	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
		goto bad_dir;

	dir->nr_buffers = blk;

	return 0;

bad_dir:
	adfs_error(sb, "corrupted directory fragment %lX",
		   object_id);
release_buffers:
	for (blk -= 1; blk >= 0; blk -= 1)
		brelse(dir->bh[blk]);

	dir->sb = NULL;

	return -EIO;
}

/*
 * convert a disk-based directory entry to a Linux ADFS directory entry
 */
static inline void
adfs_dir2obj(struct object_info *obj, struct adfs_direntry *de)
{
	obj->name_len =	adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
	obj->file_id  = adfs_readval(de->dirinddiscadd, 3);
	obj->loadaddr = adfs_readval(de->dirload, 4);
	obj->execaddr = adfs_readval(de->direxec, 4);
	obj->size     = adfs_readval(de->dirlen,  4);
	obj->attr     = de->newdiratts;
}

/*
 * convert a Linux ADFS directory entry to a disk-based directory entry
 */
static inline void
adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
{
	adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
	adfs_writeval(de->dirload, 4, obj->loadaddr);
	adfs_writeval(de->direxec, 4, obj->execaddr);
	adfs_writeval(de->dirlen,  4, obj->size);
	de->newdiratts = obj->attr;
}

/*
 * get a directory entry.  Note that the caller is responsible
 * for holding the relevant locks.
 */
static int
__adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
{
	struct super_block *sb = dir->sb;
	struct adfs_direntry de;
	int thissize, buffer, offset;

	buffer = pos >> sb->s_blocksize_bits;

	if (buffer > dir->nr_buffers)
		return -EINVAL;

	offset = pos & (sb->s_blocksize - 1);
	thissize = sb->s_blocksize - offset;
	if (thissize > 26)
		thissize = 26;

	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
	if (thissize != 26)
		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
		       26 - thissize);

	if (!de.dirobname[0])
		return -ENOENT;

	adfs_dir2obj(obj, &de);

	return 0;
}

static int
__adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
{
	struct super_block *sb = dir->sb;
	struct adfs_direntry de;
	int thissize, buffer, offset;

	buffer = pos >> sb->s_blocksize_bits;

	if (buffer > dir->nr_buffers)
		return -EINVAL;

	offset = pos & (sb->s_blocksize - 1);
	thissize = sb->s_blocksize - offset;
	if (thissize > 26)
		thissize = 26;

	/*
	 * Get the entry in total
	 */
	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
	if (thissize != 26)
		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
		       26 - thissize);

	/*
	 * update it
	 */
	adfs_obj2dir(&de, obj);

	/*
	 * Put the new entry back
	 */
	memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
	if (thissize != 26)
		memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
		       26 - thissize);

	return 0;
}

/*
 * the caller is responsible for holding the necessary
 * locks.
 */
static int
adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
{
	int pos, ret;

	ret = -ENOENT;

	for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
		struct object_info obj;

		if (!__adfs_dir_get(dir, pos, &obj))
			break;

		if (obj.file_id == object_id) {
			ret = pos;
			break;
		}
	}

	return ret;
}

static int
adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
{
	int ret;

	if (sz != ADFS_NEWDIR_SIZE)
		return -EIO;

	ret = adfs_dir_read(sb, id, sz, dir);
	if (ret)
		adfs_error(sb, "unable to read directory");
	else
		dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);

	return ret;
}

static int
adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
{
	if (fpos >= ADFS_NUM_DIR_ENTRIES)
		return -ENOENT;

	dir->pos = 5 + fpos * 26;
	return 0;
}

static int
adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
{
	unsigned int ret;

	ret = __adfs_dir_get(dir, dir->pos, obj);
	if (ret == 0)
		dir->pos += 26;

	return ret;
}

static int
adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
{
	struct super_block *sb = dir->sb;
	int ret, i;

	ret = adfs_dir_find_entry(dir, obj->file_id);
	if (ret < 0) {
		adfs_error(dir->sb, "unable to locate entry to update");
		goto out;
	}

	__adfs_dir_put(dir, ret, obj);
 
	/*
	 * Increment directory sequence number
	 */
	dir->bh[0]->b_data[0] += 1;
	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;

	ret = adfs_dir_checkbyte(dir);
	/*
	 * Update directory check byte
	 */
	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;

#if 1
	{
	const unsigned int blocksize_bits = sb->s_blocksize_bits;

	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));

	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
		goto bad_dir;

	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
	    memcmp(&dir->dirhead.startname, "Hugo", 4))
		goto bad_dir;

	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
		goto bad_dir;
	}
#endif
	for (i = dir->nr_buffers - 1; i >= 0; i--)
		mark_buffer_dirty(dir->bh[i]);

	ret = 0;
out:
	return ret;
#if 1
bad_dir:
	adfs_error(dir->sb, "whoops!  I broke a directory!");
	return -EIO;
#endif
}

static void
adfs_f_free(struct adfs_dir *dir)
{
	int i;

	for (i = dir->nr_buffers - 1; i >= 0; i--) {
		brelse(dir->bh[i]);
		dir->bh[i] = NULL;
	}

	dir->nr_buffers = 0;
	dir->sb = NULL;
}

struct adfs_dir_ops adfs_f_dir_ops = {
	.read		= adfs_f_read,
	.setpos		= adfs_f_setpos,
	.getnext	= adfs_f_getnext,
	.update		= adfs_f_update,
	.free		= adfs_f_free
};