1/*
2 *  linux/fs/adfs/dir_f.c
3 *
4 * Copyright (C) 1997-1999 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 *  E and F format directory handling
11 */
12#include <linux/buffer_head.h>
13#include "adfs.h"
14#include "dir_f.h"
15
16static void adfs_f_free(struct adfs_dir *dir);
17
18/*
19 * Read an (unaligned) value of length 1..4 bytes
20 */
21static inline unsigned int adfs_readval(unsigned char *p, int len)
22{
23	unsigned int val = 0;
24
25	switch (len) {
26	case 4:		val |= p[3] << 24;
27	case 3:		val |= p[2] << 16;
28	case 2:		val |= p[1] << 8;
29	default:	val |= p[0];
30	}
31	return val;
32}
33
34static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
35{
36	switch (len) {
37	case 4:		p[3] = val >> 24;
38	case 3:		p[2] = val >> 16;
39	case 2:		p[1] = val >> 8;
40	default:	p[0] = val;
41	}
42}
43
44static inline int adfs_readname(char *buf, char *ptr, int maxlen)
45{
46	char *old_buf = buf;
47
48	while ((unsigned char)*ptr >= ' ' && maxlen--) {
49		if (*ptr == '/')
50			*buf++ = '.';
51		else
52			*buf++ = *ptr;
53		ptr++;
54	}
55	*buf = '\0';
56
57	return buf - old_buf;
58}
59
60#define ror13(v) ((v >> 13) | (v << 19))
61
62#define dir_u8(idx)				\
63	({ int _buf = idx >> blocksize_bits;	\
64	   int _off = idx - (_buf << blocksize_bits);\
65	  *(u8 *)(bh[_buf]->b_data + _off);	\
66	})
67
68#define dir_u32(idx)				\
69	({ int _buf = idx >> blocksize_bits;	\
70	   int _off = idx - (_buf << blocksize_bits);\
71	  *(__le32 *)(bh[_buf]->b_data + _off);	\
72	})
73
74#define bufoff(_bh,_idx)			\
75	({ int _buf = _idx >> blocksize_bits;	\
76	   int _off = _idx - (_buf << blocksize_bits);\
77	  (u8 *)(_bh[_buf]->b_data + _off);	\
78	})
79
80/*
81 * There are some algorithms that are nice in
82 * assembler, but a bitch in C...  This is one
83 * of them.
84 */
85static u8
86adfs_dir_checkbyte(const struct adfs_dir *dir)
87{
88	struct buffer_head * const *bh = dir->bh;
89	const int blocksize_bits = dir->sb->s_blocksize_bits;
90	union { __le32 *ptr32; u8 *ptr8; } ptr, end;
91	u32 dircheck = 0;
92	int last = 5 - 26;
93	int i = 0;
94
95	/*
96	 * Accumulate each word up to the last whole
97	 * word of the last directory entry.  This
98	 * can spread across several buffer heads.
99	 */
100	do {
101		last += 26;
102		do {
103			dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
104
105			i += sizeof(u32);
106		} while (i < (last & ~3));
107	} while (dir_u8(last) != 0);
108
109	/*
110	 * Accumulate the last few bytes.  These
111	 * bytes will be within the same bh.
112	 */
113	if (i != last) {
114		ptr.ptr8 = bufoff(bh, i);
115		end.ptr8 = ptr.ptr8 + last - i;
116
117		do {
118			dircheck = *ptr.ptr8++ ^ ror13(dircheck);
119		} while (ptr.ptr8 < end.ptr8);
120	}
121
122	/*
123	 * The directory tail is in the final bh
124	 * Note that contary to the RISC OS PRMs,
125	 * the first few bytes are NOT included
126	 * in the check.  All bytes are in the
127	 * same bh.
128	 */
129	ptr.ptr8 = bufoff(bh, 2008);
130	end.ptr8 = ptr.ptr8 + 36;
131
132	do {
133		__le32 v = *ptr.ptr32++;
134		dircheck = le32_to_cpu(v) ^ ror13(dircheck);
135	} while (ptr.ptr32 < end.ptr32);
136
137	return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
138}
139
140/*
141 * Read and check that a directory is valid
142 */
143static int
144adfs_dir_read(struct super_block *sb, unsigned long object_id,
145	      unsigned int size, struct adfs_dir *dir)
146{
147	const unsigned int blocksize_bits = sb->s_blocksize_bits;
148	int blk = 0;
149
150	/*
151	 * Directories which are not a multiple of 2048 bytes
152	 * are considered bad v2 [3.6]
153	 */
154	if (size & 2047)
155		goto bad_dir;
156
157	size >>= blocksize_bits;
158
159	dir->nr_buffers = 0;
160	dir->sb = sb;
161
162	for (blk = 0; blk < size; blk++) {
163		int phys;
164
165		phys = __adfs_block_map(sb, object_id, blk);
166		if (!phys) {
167			adfs_error(sb, "dir object %lX has a hole at offset %d",
168				   object_id, blk);
169			goto release_buffers;
170		}
171
172		dir->bh[blk] = sb_bread(sb, phys);
173		if (!dir->bh[blk])
174			goto release_buffers;
175	}
176
177	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
178	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
179
180	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
181	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
182		goto bad_dir;
183
184	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
185	    memcmp(&dir->dirhead.startname, "Hugo", 4))
186		goto bad_dir;
187
188	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
189		goto bad_dir;
190
191	dir->nr_buffers = blk;
192
193	return 0;
194
195bad_dir:
196	adfs_error(sb, "corrupted directory fragment %lX",
197		   object_id);
198release_buffers:
199	for (blk -= 1; blk >= 0; blk -= 1)
200		brelse(dir->bh[blk]);
201
202	dir->sb = NULL;
203
204	return -EIO;
205}
206
207/*
208 * convert a disk-based directory entry to a Linux ADFS directory entry
209 */
210static inline void
211adfs_dir2obj(struct object_info *obj, struct adfs_direntry *de)
212{
213	obj->name_len =	adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
214	obj->file_id  = adfs_readval(de->dirinddiscadd, 3);
215	obj->loadaddr = adfs_readval(de->dirload, 4);
216	obj->execaddr = adfs_readval(de->direxec, 4);
217	obj->size     = adfs_readval(de->dirlen,  4);
218	obj->attr     = de->newdiratts;
219}
220
221/*
222 * convert a Linux ADFS directory entry to a disk-based directory entry
223 */
224static inline void
225adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
226{
227	adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
228	adfs_writeval(de->dirload, 4, obj->loadaddr);
229	adfs_writeval(de->direxec, 4, obj->execaddr);
230	adfs_writeval(de->dirlen,  4, obj->size);
231	de->newdiratts = obj->attr;
232}
233
234/*
235 * get a directory entry.  Note that the caller is responsible
236 * for holding the relevant locks.
237 */
238static int
239__adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
240{
241	struct super_block *sb = dir->sb;
242	struct adfs_direntry de;
243	int thissize, buffer, offset;
244
245	buffer = pos >> sb->s_blocksize_bits;
246
247	if (buffer > dir->nr_buffers)
248		return -EINVAL;
249
250	offset = pos & (sb->s_blocksize - 1);
251	thissize = sb->s_blocksize - offset;
252	if (thissize > 26)
253		thissize = 26;
254
255	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
256	if (thissize != 26)
257		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
258		       26 - thissize);
259
260	if (!de.dirobname[0])
261		return -ENOENT;
262
263	adfs_dir2obj(obj, &de);
264
265	return 0;
266}
267
268static int
269__adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
270{
271	struct super_block *sb = dir->sb;
272	struct adfs_direntry de;
273	int thissize, buffer, offset;
274
275	buffer = pos >> sb->s_blocksize_bits;
276
277	if (buffer > dir->nr_buffers)
278		return -EINVAL;
279
280	offset = pos & (sb->s_blocksize - 1);
281	thissize = sb->s_blocksize - offset;
282	if (thissize > 26)
283		thissize = 26;
284
285	/*
286	 * Get the entry in total
287	 */
288	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
289	if (thissize != 26)
290		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
291		       26 - thissize);
292
293	/*
294	 * update it
295	 */
296	adfs_obj2dir(&de, obj);
297
298	/*
299	 * Put the new entry back
300	 */
301	memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
302	if (thissize != 26)
303		memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
304		       26 - thissize);
305
306	return 0;
307}
308
309/*
310 * the caller is responsible for holding the necessary
311 * locks.
312 */
313static int
314adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
315{
316	int pos, ret;
317
318	ret = -ENOENT;
319
320	for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
321		struct object_info obj;
322
323		if (!__adfs_dir_get(dir, pos, &obj))
324			break;
325
326		if (obj.file_id == object_id) {
327			ret = pos;
328			break;
329		}
330	}
331
332	return ret;
333}
334
335static int
336adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
337{
338	int ret;
339
340	if (sz != ADFS_NEWDIR_SIZE)
341		return -EIO;
342
343	ret = adfs_dir_read(sb, id, sz, dir);
344	if (ret)
345		adfs_error(sb, "unable to read directory");
346	else
347		dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
348
349	return ret;
350}
351
352static int
353adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
354{
355	if (fpos >= ADFS_NUM_DIR_ENTRIES)
356		return -ENOENT;
357
358	dir->pos = 5 + fpos * 26;
359	return 0;
360}
361
362static int
363adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
364{
365	unsigned int ret;
366
367	ret = __adfs_dir_get(dir, dir->pos, obj);
368	if (ret == 0)
369		dir->pos += 26;
370
371	return ret;
372}
373
374static int
375adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
376{
377	struct super_block *sb = dir->sb;
378	int ret, i;
379
380	ret = adfs_dir_find_entry(dir, obj->file_id);
381	if (ret < 0) {
382		adfs_error(dir->sb, "unable to locate entry to update");
383		goto out;
384	}
385
386	__adfs_dir_put(dir, ret, obj);
387
388	/*
389	 * Increment directory sequence number
390	 */
391	dir->bh[0]->b_data[0] += 1;
392	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
393
394	ret = adfs_dir_checkbyte(dir);
395	/*
396	 * Update directory check byte
397	 */
398	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
399
400	{
401	const unsigned int blocksize_bits = sb->s_blocksize_bits;
402
403	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
404	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
405
406	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
407	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
408		goto bad_dir;
409
410	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
411	    memcmp(&dir->dirhead.startname, "Hugo", 4))
412		goto bad_dir;
413
414	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
415		goto bad_dir;
416	}
417	for (i = dir->nr_buffers - 1; i >= 0; i--)
418		mark_buffer_dirty(dir->bh[i]);
419
420	ret = 0;
421out:
422	return ret;
423bad_dir:
424	adfs_error(dir->sb, "whoops!  I broke a directory!");
425	return -EIO;
426}
427
428static int
429adfs_f_sync(struct adfs_dir *dir)
430{
431	int err = 0;
432	int i;
433
434	for (i = dir->nr_buffers - 1; i >= 0; i--) {
435		struct buffer_head *bh = dir->bh[i];
436		sync_dirty_buffer(bh);
437		if (buffer_req(bh) && !buffer_uptodate(bh))
438			err = -EIO;
439	}
440
441	return err;
442}
443
444static void
445adfs_f_free(struct adfs_dir *dir)
446{
447	int i;
448
449	for (i = dir->nr_buffers - 1; i >= 0; i--) {
450		brelse(dir->bh[i]);
451		dir->bh[i] = NULL;
452	}
453
454	dir->nr_buffers = 0;
455	dir->sb = NULL;
456}
457
458struct adfs_dir_ops adfs_f_dir_ops = {
459	.read		= adfs_f_read,
460	.setpos		= adfs_f_setpos,
461	.getnext	= adfs_f_getnext,
462	.update		= adfs_f_update,
463	.sync		= adfs_f_sync,
464	.free		= adfs_f_free
465};
466