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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 | |
16 | static void adfs_f_free(struct adfs_dir *dir); |
17 | |
18 | /* |
19 | * Read an (unaligned) value of length 1..4 bytes |
20 | */ |
21 | static 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 | |
34 | static 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 | |
44 | static 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 | */ |
85 | static u8 |
86 | adfs_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 | */ |
143 | static int |
144 | adfs_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 | |
195 | bad_dir: |
196 | adfs_error(sb, "corrupted directory fragment %lX", |
197 | object_id); |
198 | release_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 | */ |
210 | static inline void |
211 | adfs_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 | */ |
224 | static inline void |
225 | adfs_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 | */ |
238 | static 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 | |
268 | static 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 | */ |
313 | static int |
314 | adfs_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 | |
335 | static int |
336 | adfs_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 | |
352 | static int |
353 | adfs_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 | |
362 | static int |
363 | adfs_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 | |
374 | static int |
375 | adfs_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 | #if 1 |
401 | { |
402 | const unsigned int blocksize_bits = sb->s_blocksize_bits; |
403 | |
404 | memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead)); |
405 | memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail)); |
406 | |
407 | if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq || |
408 | memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4)) |
409 | goto bad_dir; |
410 | |
411 | if (memcmp(&dir->dirhead.startname, "Nick", 4) && |
412 | memcmp(&dir->dirhead.startname, "Hugo", 4)) |
413 | goto bad_dir; |
414 | |
415 | if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte) |
416 | goto bad_dir; |
417 | } |
418 | #endif |
419 | for (i = dir->nr_buffers - 1; i >= 0; i--) |
420 | mark_buffer_dirty(dir->bh[i]); |
421 | |
422 | ret = 0; |
423 | out: |
424 | return ret; |
425 | #if 1 |
426 | bad_dir: |
427 | adfs_error(dir->sb, "whoops! I broke a directory!"); |
428 | return -EIO; |
429 | #endif |
430 | } |
431 | |
432 | static int |
433 | adfs_f_sync(struct adfs_dir *dir) |
434 | { |
435 | int err = 0; |
436 | int i; |
437 | |
438 | for (i = dir->nr_buffers - 1; i >= 0; i--) { |
439 | struct buffer_head *bh = dir->bh[i]; |
440 | sync_dirty_buffer(bh); |
441 | if (buffer_req(bh) && !buffer_uptodate(bh)) |
442 | err = -EIO; |
443 | } |
444 | |
445 | return err; |
446 | } |
447 | |
448 | static void |
449 | adfs_f_free(struct adfs_dir *dir) |
450 | { |
451 | int i; |
452 | |
453 | for (i = dir->nr_buffers - 1; i >= 0; i--) { |
454 | brelse(dir->bh[i]); |
455 | dir->bh[i] = NULL; |
456 | } |
457 | |
458 | dir->nr_buffers = 0; |
459 | dir->sb = NULL; |
460 | } |
461 | |
462 | struct adfs_dir_ops adfs_f_dir_ops = { |
463 | .read = adfs_f_read, |
464 | .setpos = adfs_f_setpos, |
465 | .getnext = adfs_f_getnext, |
466 | .update = adfs_f_update, |
467 | .sync = adfs_f_sync, |
468 | .free = adfs_f_free |
469 | }; |
470 |
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