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
56	return buf - old_buf;
57}
58
59#define ror13(v) ((v >> 13) | (v << 19))
60
61#define dir_u8(idx)				\
62	({ int _buf = idx >> blocksize_bits;	\
63	   int _off = idx - (_buf << blocksize_bits);\
64	  *(u8 *)(bh[_buf]->b_data + _off);	\
65	})
66
67#define dir_u32(idx)				\
68	({ int _buf = idx >> blocksize_bits;	\
69	   int _off = idx - (_buf << blocksize_bits);\
70	  *(__le32 *)(bh[_buf]->b_data + _off);	\
71	})
72
73#define bufoff(_bh,_idx)			\
74	({ int _buf = _idx >> blocksize_bits;	\
75	   int _off = _idx - (_buf << blocksize_bits);\
76	  (u8 *)(_bh[_buf]->b_data + _off);	\
77	})
78
79/*
80 * There are some algorithms that are nice in
81 * assembler, but a bitch in C...  This is one
82 * of them.
83 */
84static u8
85adfs_dir_checkbyte(const struct adfs_dir *dir)
86{
87	struct buffer_head * const *bh = dir->bh;
88	const int blocksize_bits = dir->sb->s_blocksize_bits;
89	union { __le32 *ptr32; u8 *ptr8; } ptr, end;
90	u32 dircheck = 0;
91	int last = 5 - 26;
92	int i = 0;
93
94	/*
95	 * Accumulate each word up to the last whole
96	 * word of the last directory entry.  This
97	 * can spread across several buffer heads.
98	 */
99	do {
100		last += 26;
101		do {
102			dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
103
104			i += sizeof(u32);
105		} while (i < (last & ~3));
106	} while (dir_u8(last) != 0);
107
108	/*
109	 * Accumulate the last few bytes.  These
110	 * bytes will be within the same bh.
111	 */
112	if (i != last) {
113		ptr.ptr8 = bufoff(bh, i);
114		end.ptr8 = ptr.ptr8 + last - i;
115
116		do {
117			dircheck = *ptr.ptr8++ ^ ror13(dircheck);
118		} while (ptr.ptr8 < end.ptr8);
119	}
120
121	/*
122	 * The directory tail is in the final bh
123	 * Note that contary to the RISC OS PRMs,
124	 * the first few bytes are NOT included
125	 * in the check.  All bytes are in the
126	 * same bh.
127	 */
128	ptr.ptr8 = bufoff(bh, 2008);
129	end.ptr8 = ptr.ptr8 + 36;
130
131	do {
132		__le32 v = *ptr.ptr32++;
133		dircheck = le32_to_cpu(v) ^ ror13(dircheck);
134	} while (ptr.ptr32 < end.ptr32);
135
136	return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
137}
138
139/*
140 * Read and check that a directory is valid
141 */
142static int
143adfs_dir_read(struct super_block *sb, unsigned long object_id,
144	      unsigned int size, struct adfs_dir *dir)
145{
146	const unsigned int blocksize_bits = sb->s_blocksize_bits;
147	int blk = 0;
148
149	/*
150	 * Directories which are not a multiple of 2048 bytes
151	 * are considered bad v2 [3.6]
152	 */
153	if (size & 2047)
154		goto bad_dir;
155
156	size >>= blocksize_bits;
157
158	dir->nr_buffers = 0;
159	dir->sb = sb;
160
161	for (blk = 0; blk < size; blk++) {
162		int phys;
163
164		phys = __adfs_block_map(sb, object_id, blk);
165		if (!phys) {
166			adfs_error(sb, "dir object %lX has a hole at offset %d",
167				   object_id, blk);
168			goto release_buffers;
169		}
170
171		dir->bh[blk] = sb_bread(sb, phys);
172		if (!dir->bh[blk])
173			goto release_buffers;
174	}
175
176	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
177	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
178
179	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
180	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
181		goto bad_dir;
182
183	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
184	    memcmp(&dir->dirhead.startname, "Hugo", 4))
185		goto bad_dir;
186
187	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
188		goto bad_dir;
189
190	dir->nr_buffers = blk;
191
192	return 0;
193
194bad_dir:
195	adfs_error(sb, "corrupted directory fragment %lX",
196		   object_id);
197release_buffers:
198	for (blk -= 1; blk >= 0; blk -= 1)
199		brelse(dir->bh[blk]);
200
201	dir->sb = NULL;
202
203	return -EIO;
204}
205
206/*
207 * convert a disk-based directory entry to a Linux ADFS directory entry
208 */
209static inline void
210adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj,
211	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	obj->filetype = -1;
220
221	/*
222	 * object is a file and is filetyped and timestamped?
223	 * RISC OS 12-bit filetype is stored in load_address[19:8]
224	 */
225	if ((0 == (obj->attr & ADFS_NDA_DIRECTORY)) &&
226		(0xfff00000 == (0xfff00000 & obj->loadaddr))) {
227		obj->filetype = (__u16) ((0x000fff00 & obj->loadaddr) >> 8);
228
229		/* optionally append the ,xyz hex filetype suffix */
230		if (ADFS_SB(dir->sb)->s_ftsuffix)
231			obj->name_len +=
232				append_filetype_suffix(
233					&obj->name[obj->name_len],
234					obj->filetype);
235	}
236}
237
238/*
239 * convert a Linux ADFS directory entry to a disk-based directory entry
240 */
241static inline void
242adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
243{
244	adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
245	adfs_writeval(de->dirload, 4, obj->loadaddr);
246	adfs_writeval(de->direxec, 4, obj->execaddr);
247	adfs_writeval(de->dirlen,  4, obj->size);
248	de->newdiratts = obj->attr;
249}
250
251/*
252 * get a directory entry.  Note that the caller is responsible
253 * for holding the relevant locks.
254 */
255static int
256__adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
257{
258	struct super_block *sb = dir->sb;
259	struct adfs_direntry de;
260	int thissize, buffer, offset;
261
262	buffer = pos >> sb->s_blocksize_bits;
263
264	if (buffer > dir->nr_buffers)
265		return -EINVAL;
266
267	offset = pos & (sb->s_blocksize - 1);
268	thissize = sb->s_blocksize - offset;
269	if (thissize > 26)
270		thissize = 26;
271
272	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
273	if (thissize != 26)
274		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
275		       26 - thissize);
276
277	if (!de.dirobname[0])
278		return -ENOENT;
279
280	adfs_dir2obj(dir, obj, &de);
281
282	return 0;
283}
284
285static int
286__adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
287{
288	struct super_block *sb = dir->sb;
289	struct adfs_direntry de;
290	int thissize, buffer, offset;
291
292	buffer = pos >> sb->s_blocksize_bits;
293
294	if (buffer > dir->nr_buffers)
295		return -EINVAL;
296
297	offset = pos & (sb->s_blocksize - 1);
298	thissize = sb->s_blocksize - offset;
299	if (thissize > 26)
300		thissize = 26;
301
302	/*
303	 * Get the entry in total
304	 */
305	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
306	if (thissize != 26)
307		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
308		       26 - thissize);
309
310	/*
311	 * update it
312	 */
313	adfs_obj2dir(&de, obj);
314
315	/*
316	 * Put the new entry back
317	 */
318	memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
319	if (thissize != 26)
320		memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
321		       26 - thissize);
322
323	return 0;
324}
325
326/*
327 * the caller is responsible for holding the necessary
328 * locks.
329 */
330static int
331adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
332{
333	int pos, ret;
334
335	ret = -ENOENT;
336
337	for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
338		struct object_info obj;
339
340		if (!__adfs_dir_get(dir, pos, &obj))
341			break;
342
343		if (obj.file_id == object_id) {
344			ret = pos;
345			break;
346		}
347	}
348
349	return ret;
350}
351
352static int
353adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
354{
355	int ret;
356
357	if (sz != ADFS_NEWDIR_SIZE)
358		return -EIO;
359
360	ret = adfs_dir_read(sb, id, sz, dir);
361	if (ret)
362		adfs_error(sb, "unable to read directory");
363	else
364		dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
365
366	return ret;
367}
368
369static int
370adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
371{
372	if (fpos >= ADFS_NUM_DIR_ENTRIES)
373		return -ENOENT;
374
375	dir->pos = 5 + fpos * 26;
376	return 0;
377}
378
379static int
380adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
381{
382	unsigned int ret;
383
384	ret = __adfs_dir_get(dir, dir->pos, obj);
385	if (ret == 0)
386		dir->pos += 26;
387
388	return ret;
389}
390
391static int
392adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
393{
394	struct super_block *sb = dir->sb;
395	int ret, i;
396
397	ret = adfs_dir_find_entry(dir, obj->file_id);
398	if (ret < 0) {
399		adfs_error(dir->sb, "unable to locate entry to update");
400		goto out;
401	}
402
403	__adfs_dir_put(dir, ret, obj);
404
405	/*
406	 * Increment directory sequence number
407	 */
408	dir->bh[0]->b_data[0] += 1;
409	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
410
411	ret = adfs_dir_checkbyte(dir);
412	/*
413	 * Update directory check byte
414	 */
415	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
416
417#if 1
418	{
419	const unsigned int blocksize_bits = sb->s_blocksize_bits;
420
421	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
422	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
423
424	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
425	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
426		goto bad_dir;
427
428	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
429	    memcmp(&dir->dirhead.startname, "Hugo", 4))
430		goto bad_dir;
431
432	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
433		goto bad_dir;
434	}
435#endif
436	for (i = dir->nr_buffers - 1; i >= 0; i--)
437		mark_buffer_dirty(dir->bh[i]);
438
439	ret = 0;
440out:
441	return ret;
442#if 1
443bad_dir:
444	adfs_error(dir->sb, "whoops!  I broke a directory!");
445	return -EIO;
446#endif
447}
448
449static int
450adfs_f_sync(struct adfs_dir *dir)
451{
452	int err = 0;
453	int i;
454
455	for (i = dir->nr_buffers - 1; i >= 0; i--) {
456		struct buffer_head *bh = dir->bh[i];
457		sync_dirty_buffer(bh);
458		if (buffer_req(bh) && !buffer_uptodate(bh))
459			err = -EIO;
460	}
461
462	return err;
463}
464
465static void
466adfs_f_free(struct adfs_dir *dir)
467{
468	int i;
469
470	for (i = dir->nr_buffers - 1; i >= 0; i--) {
471		brelse(dir->bh[i]);
472		dir->bh[i] = NULL;
473	}
474
475	dir->nr_buffers = 0;
476	dir->sb = NULL;
477}
478
479struct adfs_dir_ops adfs_f_dir_ops = {
480	.read		= adfs_f_read,
481	.setpos		= adfs_f_setpos,
482	.getnext	= adfs_f_getnext,
483	.update		= adfs_f_update,
484	.sync		= adfs_f_sync,
485	.free		= adfs_f_free
486};
487