File: /usr/src/linux/fs/adfs/dir_f.c
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/version.h>
13 #include <linux/errno.h>
14 #include <linux/fs.h>
15 #include <linux/adfs_fs.h>
16 #include <linux/sched.h>
17 #include <linux/stat.h>
18 #include <linux/spinlock.h>
19
20 #include "adfs.h"
21 #include "dir_f.h"
22
23 static void adfs_f_free(struct adfs_dir *dir);
24
25 /*
26 * Read an (unaligned) value of length 1..4 bytes
27 */
28 static inline unsigned int adfs_readval(unsigned char *p, int len)
29 {
30 unsigned int val = 0;
31
32 switch (len) {
33 case 4: val |= p[3] << 24;
34 case 3: val |= p[2] << 16;
35 case 2: val |= p[1] << 8;
36 default: val |= p[0];
37 }
38 return val;
39 }
40
41 static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
42 {
43 switch (len) {
44 case 4: p[3] = val >> 24;
45 case 3: p[2] = val >> 16;
46 case 2: p[1] = val >> 8;
47 default: p[0] = val;
48 }
49 }
50
51 static inline int adfs_readname(char *buf, char *ptr, int maxlen)
52 {
53 char *old_buf = buf;
54
55 while (*ptr >= ' ' && maxlen--) {
56 if (*ptr == '/')
57 *buf++ = '.';
58 else
59 *buf++ = *ptr;
60 ptr++;
61 }
62 *buf = '\0';
63
64 return buf - old_buf;
65 }
66
67 static inline void adfs_writename(char *to, char *from, int maxlen)
68 {
69 int i;
70
71 for (i = 0; i < maxlen; i++) {
72 if (from[i] == '\0')
73 break;
74 if (from[i] == '.')
75 to[i] = '/';
76 else
77 to[i] = from[i];
78 }
79
80 for (; i < maxlen; i++)
81 to[i] = '\0';
82 }
83
84 #define ror13(v) ((v >> 13) | (v << 19))
85
86 #define dir_u8(idx) \
87 ({ int _buf = idx >> blocksize_bits; \
88 int _off = idx - (_buf << blocksize_bits);\
89 *(u8 *)(bh[_buf]->b_data + _off); \
90 })
91
92 #define dir_u32(idx) \
93 ({ int _buf = idx >> blocksize_bits; \
94 int _off = idx - (_buf << blocksize_bits);\
95 *(u32 *)(bh[_buf]->b_data + _off); \
96 })
97
98 #define bufoff(_bh,_idx) \
99 ({ int _buf = _idx >> blocksize_bits; \
100 int _off = _idx - (_buf << blocksize_bits);\
101 (u8 *)(_bh[_buf]->b_data + _off); \
102 })
103
104 /*
105 * There are some algorithms that are nice in
106 * assembler, but a bitch in C... This is one
107 * of them.
108 */
109 static u8
110 adfs_dir_checkbyte(const struct adfs_dir *dir)
111 {
112 struct buffer_head * const *bh = dir->bh;
113 const int blocksize_bits = dir->sb->s_blocksize_bits;
114 union { u32 *ptr32; u8 *ptr8; } ptr, end;
115 u32 dircheck = 0;
116 int last = 5 - 26;
117 int i = 0;
118
119 /*
120 * Accumulate each word up to the last whole
121 * word of the last directory entry. This
122 * can spread across several buffer heads.
123 */
124 do {
125 last += 26;
126 do {
127 dircheck = cpu_to_le32(dir_u32(i)) ^ ror13(dircheck);
128
129 i += sizeof(u32);
130 } while (i < (last & ~3));
131 } while (dir_u8(last) != 0);
132
133 /*
134 * Accumulate the last few bytes. These
135 * bytes will be within the same bh.
136 */
137 if (i != last) {
138 ptr.ptr8 = bufoff(bh, i);
139 end.ptr8 = ptr.ptr8 + last - i;
140
141 do
142 dircheck = *ptr.ptr8++ ^ ror13(dircheck);
143 while (ptr.ptr8 < end.ptr8);
144 }
145
146 /*
147 * The directory tail is in the final bh
148 * Note that contary to the RISC OS PRMs,
149 * the first few bytes are NOT included
150 * in the check. All bytes are in the
151 * same bh.
152 */
153 ptr.ptr8 = bufoff(bh, 2008);
154 end.ptr8 = ptr.ptr8 + 36;
155
156 do {
157 unsigned int v = *ptr.ptr32++;
158 dircheck = cpu_to_le32(v) ^ ror13(dircheck);
159 } while (ptr.ptr32 < end.ptr32);
160
161 return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
162 }
163
164 /*
165 * Read and check that a directory is valid
166 */
167 int
168 adfs_dir_read(struct super_block *sb, unsigned long object_id,
169 unsigned int size, struct adfs_dir *dir)
170 {
171 const unsigned int blocksize_bits = sb->s_blocksize_bits;
172 int blk = 0;
173
174 /*
175 * Directories which are not a multiple of 2048 bytes
176 * are considered bad v2 [3.6]
177 */
178 if (size & 2047)
179 goto bad_dir;
180
181 size >>= blocksize_bits;
182
183 dir->nr_buffers = 0;
184 dir->sb = sb;
185
186 for (blk = 0; blk < size; blk++) {
187 int phys;
188
189 phys = __adfs_block_map(sb, object_id, blk);
190 if (!phys) {
191 adfs_error(sb, "dir object %lX has a hole at offset %d",
192 object_id, blk);
193 goto release_buffers;
194 }
195
196 dir->bh[blk] = bread(sb->s_dev, phys, sb->s_blocksize);
197 if (!dir->bh[blk])
198 goto release_buffers;
199 }
200
201 memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
202 memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
203
204 if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
205 memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
206 goto bad_dir;
207
208 if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
209 memcmp(&dir->dirhead.startname, "Hugo", 4))
210 goto bad_dir;
211
212 if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
213 goto bad_dir;
214
215 dir->nr_buffers = blk;
216
217 return 0;
218
219 bad_dir:
220 adfs_error(sb, "corrupted directory fragment %lX",
221 object_id);
222 release_buffers:
223 for (blk -= 1; blk >= 0; blk -= 1)
224 brelse(dir->bh[blk]);
225
226 dir->sb = NULL;
227
228 return -EIO;
229 }
230
231 /*
232 * convert a disk-based directory entry to a Linux ADFS directory entry
233 */
234 static inline void
235 adfs_dir2obj(struct object_info *obj, struct adfs_direntry *de)
236 {
237 obj->name_len = adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
238 obj->file_id = adfs_readval(de->dirinddiscadd, 3);
239 obj->loadaddr = adfs_readval(de->dirload, 4);
240 obj->execaddr = adfs_readval(de->direxec, 4);
241 obj->size = adfs_readval(de->dirlen, 4);
242 obj->attr = de->newdiratts;
243 }
244
245 /*
246 * convert a Linux ADFS directory entry to a disk-based directory entry
247 */
248 static inline void
249 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
250 {
251 adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
252 adfs_writeval(de->dirload, 4, obj->loadaddr);
253 adfs_writeval(de->direxec, 4, obj->execaddr);
254 adfs_writeval(de->dirlen, 4, obj->size);
255 de->newdiratts = obj->attr;
256 }
257
258 /*
259 * get a directory entry. Note that the caller is responsible
260 * for holding the relevent locks.
261 */
262 int
263 __adfs_dir_get(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 memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
280 if (thissize != 26)
281 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
282 26 - thissize);
283
284 if (!de.dirobname[0])
285 return -ENOENT;
286
287 adfs_dir2obj(obj, &de);
288
289 return 0;
290 }
291
292 int
293 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
294 {
295 struct super_block *sb = dir->sb;
296 struct adfs_direntry de;
297 int thissize, buffer, offset;
298
299 buffer = pos >> sb->s_blocksize_bits;
300
301 if (buffer > dir->nr_buffers)
302 return -EINVAL;
303
304 offset = pos & (sb->s_blocksize - 1);
305 thissize = sb->s_blocksize - offset;
306 if (thissize > 26)
307 thissize = 26;
308
309 /*
310 * Get the entry in total
311 */
312 memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
313 if (thissize != 26)
314 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
315 26 - thissize);
316
317 /*
318 * update it
319 */
320 adfs_obj2dir(&de, obj);
321
322 /*
323 * Put the new entry back
324 */
325 memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
326 if (thissize != 26)
327 memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
328 26 - thissize);
329
330 return 0;
331 }
332
333 /*
334 * the caller is responsible for holding the necessary
335 * locks.
336 */
337 static int
338 adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
339 {
340 int pos, ret;
341
342 ret = -ENOENT;
343
344 for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
345 struct object_info obj;
346
347 if (!__adfs_dir_get(dir, pos, &obj))
348 break;
349
350 if (obj.file_id == object_id) {
351 ret = pos;
352 break;
353 }
354 }
355
356 return ret;
357 }
358
359 static int
360 adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
361 {
362 int ret;
363
364 if (sz != ADFS_NEWDIR_SIZE)
365 return -EIO;
366
367 ret = adfs_dir_read(sb, id, sz, dir);
368 if (ret)
369 adfs_error(sb, "unable to read directory");
370 else
371 dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
372
373 return ret;
374 }
375
376 static int
377 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
378 {
379 if (fpos >= ADFS_NUM_DIR_ENTRIES)
380 return -ENOENT;
381
382 dir->pos = 5 + fpos * 26;
383 return 0;
384 }
385
386 static int
387 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
388 {
389 unsigned int ret;
390
391 ret = __adfs_dir_get(dir, dir->pos, obj);
392 if (ret == 0)
393 dir->pos += 26;
394
395 return ret;
396 }
397
398 static int
399 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
400 {
401 struct super_block *sb = dir->sb;
402 int ret, i;
403
404 ret = adfs_dir_find_entry(dir, obj->file_id);
405 if (ret < 0) {
406 adfs_error(dir->sb, "unable to locate entry to update");
407 goto out;
408 }
409
410 __adfs_dir_put(dir, ret, obj);
411
412 /*
413 * Increment directory sequence number
414 */
415 dir->bh[0]->b_data[0] += 1;
416 dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
417
418 ret = adfs_dir_checkbyte(dir);
419 /*
420 * Update directory check byte
421 */
422 dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
423
424 #if 1
425 {
426 const unsigned int blocksize_bits = sb->s_blocksize_bits;
427
428 memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
429 memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
430
431 if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
432 memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
433 goto bad_dir;
434
435 if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
436 memcmp(&dir->dirhead.startname, "Hugo", 4))
437 goto bad_dir;
438
439 if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
440 goto bad_dir;
441 }
442 #endif
443 for (i = dir->nr_buffers - 1; i >= 0; i--)
444 mark_buffer_dirty(dir->bh[i]);
445
446 ret = 0;
447 out:
448 return ret;
449 #if 1
450 bad_dir:
451 adfs_error(dir->sb, "whoops! I broke a directory!");
452 return -EIO;
453 #endif
454 }
455
456 static void
457 adfs_f_free(struct adfs_dir *dir)
458 {
459 int i;
460
461 for (i = dir->nr_buffers - 1; i >= 0; i--) {
462 brelse(dir->bh[i]);
463 dir->bh[i] = NULL;
464 }
465
466 dir->nr_buffers = 0;
467 dir->sb = NULL;
468 }
469
470 struct adfs_dir_ops adfs_f_dir_ops = {
471 adfs_f_read,
472 adfs_f_setpos,
473 adfs_f_getnext,
474 adfs_f_update,
475 NULL,
476 NULL,
477 adfs_f_free
478 };
479