xref: /linux/fs/adfs/dir_f.c (revision 52338415) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/fs/adfs/dir_f.c
4  *
5  * Copyright (C) 1997-1999 Russell King
6  *
7  *  E and F format directory handling
8  */
9 #include "adfs.h"
10 #include "dir_f.h"
11 
12 static void adfs_f_free(struct adfs_dir *dir);
13 
14 /*
15  * Read an (unaligned) value of length 1..4 bytes
16  */
17 static inline unsigned int adfs_readval(unsigned char *p, int len)
18 {
19 	unsigned int val = 0;
20 
21 	switch (len) {
22 	case 4:		val |= p[3] << 24;
23 			/* fall through */
24 	case 3:		val |= p[2] << 16;
25 			/* fall through */
26 	case 2:		val |= p[1] << 8;
27 			/* fall through */
28 	default:	val |= p[0];
29 	}
30 	return val;
31 }
32 
33 static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
34 {
35 	switch (len) {
36 	case 4:		p[3] = val >> 24;
37 			/* fall through */
38 	case 3:		p[2] = val >> 16;
39 			/* fall through */
40 	case 2:		p[1] = val >> 8;
41 			/* fall through */
42 	default:	p[0] = val;
43 	}
44 }
45 
46 #define ror13(v) ((v >> 13) | (v << 19))
47 
48 #define dir_u8(idx)				\
49 	({ int _buf = idx >> blocksize_bits;	\
50 	   int _off = idx - (_buf << blocksize_bits);\
51 	  *(u8 *)(bh[_buf]->b_data + _off);	\
52 	})
53 
54 #define dir_u32(idx)				\
55 	({ int _buf = idx >> blocksize_bits;	\
56 	   int _off = idx - (_buf << blocksize_bits);\
57 	  *(__le32 *)(bh[_buf]->b_data + _off);	\
58 	})
59 
60 #define bufoff(_bh,_idx)			\
61 	({ int _buf = _idx >> blocksize_bits;	\
62 	   int _off = _idx - (_buf << blocksize_bits);\
63 	  (u8 *)(_bh[_buf]->b_data + _off);	\
64 	})
65 
66 /*
67  * There are some algorithms that are nice in
68  * assembler, but a bitch in C...  This is one
69  * of them.
70  */
71 static u8
72 adfs_dir_checkbyte(const struct adfs_dir *dir)
73 {
74 	struct buffer_head * const *bh = dir->bh;
75 	const int blocksize_bits = dir->sb->s_blocksize_bits;
76 	union { __le32 *ptr32; u8 *ptr8; } ptr, end;
77 	u32 dircheck = 0;
78 	int last = 5 - 26;
79 	int i = 0;
80 
81 	/*
82 	 * Accumulate each word up to the last whole
83 	 * word of the last directory entry.  This
84 	 * can spread across several buffer heads.
85 	 */
86 	do {
87 		last += 26;
88 		do {
89 			dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
90 
91 			i += sizeof(u32);
92 		} while (i < (last & ~3));
93 	} while (dir_u8(last) != 0);
94 
95 	/*
96 	 * Accumulate the last few bytes.  These
97 	 * bytes will be within the same bh.
98 	 */
99 	if (i != last) {
100 		ptr.ptr8 = bufoff(bh, i);
101 		end.ptr8 = ptr.ptr8 + last - i;
102 
103 		do {
104 			dircheck = *ptr.ptr8++ ^ ror13(dircheck);
105 		} while (ptr.ptr8 < end.ptr8);
106 	}
107 
108 	/*
109 	 * The directory tail is in the final bh
110 	 * Note that contary to the RISC OS PRMs,
111 	 * the first few bytes are NOT included
112 	 * in the check.  All bytes are in the
113 	 * same bh.
114 	 */
115 	ptr.ptr8 = bufoff(bh, 2008);
116 	end.ptr8 = ptr.ptr8 + 36;
117 
118 	do {
119 		__le32 v = *ptr.ptr32++;
120 		dircheck = le32_to_cpu(v) ^ ror13(dircheck);
121 	} while (ptr.ptr32 < end.ptr32);
122 
123 	return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
124 }
125 
126 /* Read and check that a directory is valid */
127 static int adfs_dir_read(struct super_block *sb, u32 indaddr,
128 			 unsigned int size, struct adfs_dir *dir)
129 {
130 	const unsigned int blocksize_bits = sb->s_blocksize_bits;
131 	int blk = 0;
132 
133 	/*
134 	 * Directories which are not a multiple of 2048 bytes
135 	 * are considered bad v2 [3.6]
136 	 */
137 	if (size & 2047)
138 		goto bad_dir;
139 
140 	size >>= blocksize_bits;
141 
142 	dir->nr_buffers = 0;
143 	dir->sb = sb;
144 
145 	for (blk = 0; blk < size; blk++) {
146 		int phys;
147 
148 		phys = __adfs_block_map(sb, indaddr, blk);
149 		if (!phys) {
150 			adfs_error(sb, "dir %06x has a hole at offset %d",
151 				   indaddr, blk);
152 			goto release_buffers;
153 		}
154 
155 		dir->bh[blk] = sb_bread(sb, phys);
156 		if (!dir->bh[blk])
157 			goto release_buffers;
158 	}
159 
160 	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
161 	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
162 
163 	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
164 	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
165 		goto bad_dir;
166 
167 	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
168 	    memcmp(&dir->dirhead.startname, "Hugo", 4))
169 		goto bad_dir;
170 
171 	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
172 		goto bad_dir;
173 
174 	dir->nr_buffers = blk;
175 
176 	return 0;
177 
178 bad_dir:
179 	adfs_error(sb, "dir %06x is corrupted", indaddr);
180 release_buffers:
181 	for (blk -= 1; blk >= 0; blk -= 1)
182 		brelse(dir->bh[blk]);
183 
184 	dir->sb = NULL;
185 
186 	return -EIO;
187 }
188 
189 /*
190  * convert a disk-based directory entry to a Linux ADFS directory entry
191  */
192 static inline void
193 adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj,
194 	struct adfs_direntry *de)
195 {
196 	unsigned int name_len;
197 
198 	for (name_len = 0; name_len < ADFS_F_NAME_LEN; name_len++) {
199 		if (de->dirobname[name_len] < ' ')
200 			break;
201 
202 		obj->name[name_len] = de->dirobname[name_len];
203 	}
204 
205 	obj->name_len =	name_len;
206 	obj->indaddr  = adfs_readval(de->dirinddiscadd, 3);
207 	obj->loadaddr = adfs_readval(de->dirload, 4);
208 	obj->execaddr = adfs_readval(de->direxec, 4);
209 	obj->size     = adfs_readval(de->dirlen,  4);
210 	obj->attr     = de->newdiratts;
211 
212 	adfs_object_fixup(dir, obj);
213 }
214 
215 /*
216  * convert a Linux ADFS directory entry to a disk-based directory entry
217  */
218 static inline void
219 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
220 {
221 	adfs_writeval(de->dirinddiscadd, 3, obj->indaddr);
222 	adfs_writeval(de->dirload, 4, obj->loadaddr);
223 	adfs_writeval(de->direxec, 4, obj->execaddr);
224 	adfs_writeval(de->dirlen,  4, obj->size);
225 	de->newdiratts = obj->attr;
226 }
227 
228 /*
229  * get a directory entry.  Note that the caller is responsible
230  * for holding the relevant locks.
231  */
232 static int
233 __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
234 {
235 	struct super_block *sb = dir->sb;
236 	struct adfs_direntry de;
237 	int thissize, buffer, offset;
238 
239 	buffer = pos >> sb->s_blocksize_bits;
240 
241 	if (buffer > dir->nr_buffers)
242 		return -EINVAL;
243 
244 	offset = pos & (sb->s_blocksize - 1);
245 	thissize = sb->s_blocksize - offset;
246 	if (thissize > 26)
247 		thissize = 26;
248 
249 	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
250 	if (thissize != 26)
251 		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
252 		       26 - thissize);
253 
254 	if (!de.dirobname[0])
255 		return -ENOENT;
256 
257 	adfs_dir2obj(dir, obj, &de);
258 
259 	return 0;
260 }
261 
262 static int
263 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
264 {
265 	struct super_block *sb = dir->sb;
266 	struct adfs_direntry de;
267 	int thissize, buffer, offset;
268 
269 	buffer = pos >> sb->s_blocksize_bits;
270 
271 	if (buffer > dir->nr_buffers)
272 		return -EINVAL;
273 
274 	offset = pos & (sb->s_blocksize - 1);
275 	thissize = sb->s_blocksize - offset;
276 	if (thissize > 26)
277 		thissize = 26;
278 
279 	/*
280 	 * Get the entry in total
281 	 */
282 	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
283 	if (thissize != 26)
284 		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
285 		       26 - thissize);
286 
287 	/*
288 	 * update it
289 	 */
290 	adfs_obj2dir(&de, obj);
291 
292 	/*
293 	 * Put the new entry back
294 	 */
295 	memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
296 	if (thissize != 26)
297 		memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
298 		       26 - thissize);
299 
300 	return 0;
301 }
302 
303 /*
304  * the caller is responsible for holding the necessary
305  * locks.
306  */
307 static int adfs_dir_find_entry(struct adfs_dir *dir, u32 indaddr)
308 {
309 	int pos, ret;
310 
311 	ret = -ENOENT;
312 
313 	for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
314 		struct object_info obj;
315 
316 		if (!__adfs_dir_get(dir, pos, &obj))
317 			break;
318 
319 		if (obj.indaddr == indaddr) {
320 			ret = pos;
321 			break;
322 		}
323 	}
324 
325 	return ret;
326 }
327 
328 static int adfs_f_read(struct super_block *sb, u32 indaddr, unsigned int size,
329 		       struct adfs_dir *dir)
330 {
331 	int ret;
332 
333 	if (size != ADFS_NEWDIR_SIZE)
334 		return -EIO;
335 
336 	ret = adfs_dir_read(sb, indaddr, size, dir);
337 	if (ret)
338 		adfs_error(sb, "unable to read directory");
339 	else
340 		dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
341 
342 	return ret;
343 }
344 
345 static int
346 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
347 {
348 	if (fpos >= ADFS_NUM_DIR_ENTRIES)
349 		return -ENOENT;
350 
351 	dir->pos = 5 + fpos * 26;
352 	return 0;
353 }
354 
355 static int
356 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
357 {
358 	unsigned int ret;
359 
360 	ret = __adfs_dir_get(dir, dir->pos, obj);
361 	if (ret == 0)
362 		dir->pos += 26;
363 
364 	return ret;
365 }
366 
367 static int
368 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
369 {
370 	struct super_block *sb = dir->sb;
371 	int ret, i;
372 
373 	ret = adfs_dir_find_entry(dir, obj->indaddr);
374 	if (ret < 0) {
375 		adfs_error(dir->sb, "unable to locate entry to update");
376 		goto out;
377 	}
378 
379 	__adfs_dir_put(dir, ret, obj);
380 
381 	/*
382 	 * Increment directory sequence number
383 	 */
384 	dir->bh[0]->b_data[0] += 1;
385 	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
386 
387 	ret = adfs_dir_checkbyte(dir);
388 	/*
389 	 * Update directory check byte
390 	 */
391 	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
392 
393 #if 1
394 	{
395 	const unsigned int blocksize_bits = sb->s_blocksize_bits;
396 
397 	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
398 	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
399 
400 	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
401 	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
402 		goto bad_dir;
403 
404 	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
405 	    memcmp(&dir->dirhead.startname, "Hugo", 4))
406 		goto bad_dir;
407 
408 	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
409 		goto bad_dir;
410 	}
411 #endif
412 	for (i = dir->nr_buffers - 1; i >= 0; i--)
413 		mark_buffer_dirty(dir->bh[i]);
414 
415 	ret = 0;
416 out:
417 	return ret;
418 #if 1
419 bad_dir:
420 	adfs_error(dir->sb, "whoops!  I broke a directory!");
421 	return -EIO;
422 #endif
423 }
424 
425 static int
426 adfs_f_sync(struct adfs_dir *dir)
427 {
428 	int err = 0;
429 	int i;
430 
431 	for (i = dir->nr_buffers - 1; i >= 0; i--) {
432 		struct buffer_head *bh = dir->bh[i];
433 		sync_dirty_buffer(bh);
434 		if (buffer_req(bh) && !buffer_uptodate(bh))
435 			err = -EIO;
436 	}
437 
438 	return err;
439 }
440 
441 static void
442 adfs_f_free(struct adfs_dir *dir)
443 {
444 	int i;
445 
446 	for (i = dir->nr_buffers - 1; i >= 0; i--) {
447 		brelse(dir->bh[i]);
448 		dir->bh[i] = NULL;
449 	}
450 
451 	dir->nr_buffers = 0;
452 	dir->sb = NULL;
453 }
454 
455 const struct adfs_dir_ops adfs_f_dir_ops = {
456 	.read		= adfs_f_read,
457 	.setpos		= adfs_f_setpos,
458 	.getnext	= adfs_f_getnext,
459 	.update		= adfs_f_update,
460 	.sync		= adfs_f_sync,
461 	.free		= adfs_f_free
462 };
463