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 */
adfs_readval(unsigned char * p,int len)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
adfs_writeval(unsigned char * p,int len,unsigned int val)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
adfs_dir_checkbyte(const struct adfs_dir * dir)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 */
adfs_dir_read(struct super_block * sb,u32 indaddr,unsigned int size,struct adfs_dir * dir)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
adfs_dir2obj(struct adfs_dir * dir,struct object_info * obj,struct adfs_direntry * de)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
adfs_obj2dir(struct adfs_direntry * de,struct object_info * obj)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
__adfs_dir_get(struct adfs_dir * dir,int pos,struct object_info * obj)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
__adfs_dir_put(struct adfs_dir * dir,int pos,struct object_info * obj)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 */
adfs_dir_find_entry(struct adfs_dir * dir,u32 indaddr)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
adfs_f_read(struct super_block * sb,u32 indaddr,unsigned int size,struct adfs_dir * dir)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
adfs_f_setpos(struct adfs_dir * dir,unsigned int fpos)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
adfs_f_getnext(struct adfs_dir * dir,struct object_info * obj)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
adfs_f_update(struct adfs_dir * dir,struct object_info * obj)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
adfs_f_sync(struct adfs_dir * dir)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
adfs_f_free(struct adfs_dir * dir)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