2 * linux/fs/adfs/dir_f.c
4 * Copyright (C) 1997-1999 Russell King
6 * E and F format directory handling
8 #include <linux/version.h>
9 #include <linux/errno.h>
11 #include <linux/adfs_fs.h>
12 #include <linux/sched.h>
13 #include <linux/stat.h>
14 #include <linux/spinlock.h>
19 static void adfs_f_free(struct adfs_dir
*dir
);
22 * Read an (unaligned) value of length 1..4 bytes
24 static inline unsigned int adfs_readval(unsigned char *p
, int len
)
29 case 4: val
|= p
[3] << 24;
30 case 3: val
|= p
[2] << 16;
31 case 2: val
|= p
[1] << 8;
37 static inline void adfs_writeval(unsigned char *p
, int len
, unsigned int val
)
40 case 4: p
[3] = val
>> 24;
41 case 3: p
[2] = val
>> 16;
42 case 2: p
[1] = val
>> 8;
47 static inline int adfs_readname(char *buf
, char *ptr
, int maxlen
)
51 while (*ptr
>= ' ' && maxlen
--) {
63 static inline void adfs_writename(char *to
, char *from
, int maxlen
)
67 for (i
= 0; i
< maxlen
; i
++) {
76 for (; i
< maxlen
; i
++)
80 #define ror13(v) ((v >> 13) | (v << 19))
83 ({ int _buf = idx >> blocksize_bits; \
84 int _off = idx - (_buf << blocksize_bits);\
85 *(u8 *)(bh[_buf]->b_data + _off); \
88 #define dir_u32(idx) \
89 ({ int _buf = idx >> blocksize_bits; \
90 int _off = idx - (_buf << blocksize_bits);\
91 *(u32 *)(bh[_buf]->b_data + _off); \
94 #define bufoff(_bh,_idx) \
95 ({ int _buf = _idx >> blocksize_bits; \
96 int _off = _idx - (_buf << blocksize_bits);\
97 (u8 *)(_bh[_buf]->b_data + _off); \
101 * There are some algorithms that are nice in
102 * assembler, but a bitch in C... This is one
106 adfs_dir_checkbyte(const struct adfs_dir
*dir
)
108 struct buffer_head
* const *bh
= dir
->bh
;
109 const int blocksize_bits
= dir
->sb
->s_blocksize_bits
;
110 union { u32
*ptr32
; u8
*ptr8
; } ptr
, end
;
116 * Accumulate each word up to the last whole
117 * word of the last directory entry. This
118 * can spread across several buffer heads.
123 dircheck
= cpu_to_le32(dir_u32(i
)) ^ ror13(dircheck
);
126 } while (i
< (last
& ~3));
127 } while (dir_u8(last
) != 0);
130 * Accumulate the last few bytes. These
131 * bytes will be within the same bh.
134 ptr
.ptr8
= bufoff(bh
, i
);
135 end
.ptr8
= ptr
.ptr8
+ last
- i
;
138 dircheck
= *ptr
.ptr8
++ ^ ror13(dircheck
);
139 while (ptr
.ptr8
< end
.ptr8
);
143 * The directory tail is in the final bh
144 * Note that contary to the RISC OS PRMs,
145 * the first few bytes are NOT included
146 * in the check. All bytes are in the
149 ptr
.ptr8
= bufoff(bh
, 2008);
150 end
.ptr8
= ptr
.ptr8
+ 36;
153 unsigned int v
= *ptr
.ptr32
++;
154 dircheck
= cpu_to_le32(v
) ^ ror13(dircheck
);
155 } while (ptr
.ptr32
< end
.ptr32
);
157 return (dircheck
^ (dircheck
>> 8) ^ (dircheck
>> 16) ^ (dircheck
>> 24)) & 0xff;
161 * Read and check that a directory is valid
164 adfs_dir_read(struct super_block
*sb
, unsigned long object_id
,
165 unsigned int size
, struct adfs_dir
*dir
)
167 const unsigned int blocksize_bits
= sb
->s_blocksize_bits
;
171 * Directories which are not a multiple of 2048 bytes
172 * are considered bad v2 [3.6]
177 size
>>= blocksize_bits
;
182 for (blk
= 0; blk
< size
; blk
++) {
185 phys
= __adfs_block_map(sb
, object_id
, blk
);
187 adfs_error(sb
, "dir object %lX has a hole at offset %d",
189 goto release_buffers
;
192 dir
->bh
[blk
] = bread(sb
->s_dev
, phys
, sb
->s_blocksize
);
194 goto release_buffers
;
197 memcpy(&dir
->dirhead
, bufoff(dir
->bh
, 0), sizeof(dir
->dirhead
));
198 memcpy(&dir
->dirtail
, bufoff(dir
->bh
, 2007), sizeof(dir
->dirtail
));
200 if (dir
->dirhead
.startmasseq
!= dir
->dirtail
.new.endmasseq
||
201 memcmp(&dir
->dirhead
.startname
, &dir
->dirtail
.new.endname
, 4))
204 if (memcmp(&dir
->dirhead
.startname
, "Nick", 4) &&
205 memcmp(&dir
->dirhead
.startname
, "Hugo", 4))
208 if (adfs_dir_checkbyte(dir
) != dir
->dirtail
.new.dircheckbyte
)
211 dir
->nr_buffers
= blk
;
216 adfs_error(sb
, "corrupted directory fragment %lX",
219 for (blk
-= 1; blk
>= 0; blk
-= 1)
220 brelse(dir
->bh
[blk
]);
228 * convert a disk-based directory entry to a Linux ADFS directory entry
231 adfs_dir2obj(struct object_info
*obj
, struct adfs_direntry
*de
)
233 obj
->name_len
= adfs_readname(obj
->name
, de
->dirobname
, ADFS_F_NAME_LEN
);
234 obj
->file_id
= adfs_readval(de
->dirinddiscadd
, 3);
235 obj
->loadaddr
= adfs_readval(de
->dirload
, 4);
236 obj
->execaddr
= adfs_readval(de
->direxec
, 4);
237 obj
->size
= adfs_readval(de
->dirlen
, 4);
238 obj
->attr
= de
->newdiratts
;
242 * convert a Linux ADFS directory entry to a disk-based directory entry
245 adfs_obj2dir(struct adfs_direntry
*de
, struct object_info
*obj
)
247 adfs_writeval(de
->dirinddiscadd
, 3, obj
->file_id
);
248 adfs_writeval(de
->dirload
, 4, obj
->loadaddr
);
249 adfs_writeval(de
->direxec
, 4, obj
->execaddr
);
250 adfs_writeval(de
->dirlen
, 4, obj
->size
);
251 de
->newdiratts
= obj
->attr
;
255 * get a directory entry. Note that the caller is responsible
256 * for holding the relevent locks.
259 __adfs_dir_get(struct adfs_dir
*dir
, int pos
, struct object_info
*obj
)
261 struct super_block
*sb
= dir
->sb
;
262 struct adfs_direntry de
;
263 int thissize
, buffer
, offset
;
265 buffer
= pos
>> sb
->s_blocksize_bits
;
267 if (buffer
> dir
->nr_buffers
)
270 offset
= pos
& (sb
->s_blocksize
- 1);
271 thissize
= sb
->s_blocksize
- offset
;
275 memcpy(&de
, dir
->bh
[buffer
]->b_data
+ offset
, thissize
);
277 memcpy(((char *)&de
) + thissize
, dir
->bh
[buffer
+ 1]->b_data
,
280 if (!de
.dirobname
[0])
283 adfs_dir2obj(obj
, &de
);
289 __adfs_dir_put(struct adfs_dir
*dir
, int pos
, struct object_info
*obj
)
291 struct super_block
*sb
= dir
->sb
;
292 struct adfs_direntry de
;
293 int thissize
, buffer
, offset
;
295 buffer
= pos
>> sb
->s_blocksize_bits
;
297 if (buffer
> dir
->nr_buffers
)
300 offset
= pos
& (sb
->s_blocksize
- 1);
301 thissize
= sb
->s_blocksize
- offset
;
306 * Get the entry in total
308 memcpy(&de
, dir
->bh
[buffer
]->b_data
+ offset
, thissize
);
310 memcpy(((char *)&de
) + thissize
, dir
->bh
[buffer
+ 1]->b_data
,
316 adfs_obj2dir(&de
, obj
);
319 * Put the new entry back
321 memcpy(dir
->bh
[buffer
]->b_data
+ offset
, &de
, thissize
);
323 memcpy(dir
->bh
[buffer
+ 1]->b_data
, ((char *)&de
) + thissize
,
330 * the caller is responsible for holding the necessary
334 adfs_dir_find_entry(struct adfs_dir
*dir
, unsigned long object_id
)
340 for (pos
= 5; pos
< ADFS_NUM_DIR_ENTRIES
* 26 + 5; pos
+= 26) {
341 struct object_info obj
;
343 if (!__adfs_dir_get(dir
, pos
, &obj
))
346 if (obj
.file_id
== object_id
) {
356 adfs_f_read(struct super_block
*sb
, unsigned int id
, unsigned int sz
, struct adfs_dir
*dir
)
360 if (sz
!= ADFS_NEWDIR_SIZE
)
363 ret
= adfs_dir_read(sb
, id
, sz
, dir
);
365 adfs_error(sb
, "unable to read directory");
367 dir
->parent_id
= adfs_readval(dir
->dirtail
.new.dirparent
, 3);
373 adfs_f_setpos(struct adfs_dir
*dir
, unsigned int fpos
)
375 if (fpos
>= ADFS_NUM_DIR_ENTRIES
)
378 dir
->pos
= 5 + fpos
* 26;
383 adfs_f_getnext(struct adfs_dir
*dir
, struct object_info
*obj
)
387 ret
= __adfs_dir_get(dir
, dir
->pos
, obj
);
395 adfs_f_update(struct adfs_dir
*dir
, struct object_info
*obj
)
397 struct super_block
*sb
= dir
->sb
;
400 ret
= adfs_dir_find_entry(dir
, obj
->file_id
);
402 adfs_error(dir
->sb
, "unable to locate entry to update");
406 __adfs_dir_put(dir
, ret
, obj
);
409 * Increment directory sequence number
411 dir
->bh
[0]->b_data
[0] += 1;
412 dir
->bh
[dir
->nr_buffers
- 1]->b_data
[sb
->s_blocksize
- 6] += 1;
414 ret
= adfs_dir_checkbyte(dir
);
416 * Update directory check byte
418 dir
->bh
[dir
->nr_buffers
- 1]->b_data
[sb
->s_blocksize
- 1] = ret
;
422 const unsigned int blocksize_bits
= sb
->s_blocksize_bits
;
424 memcpy(&dir
->dirhead
, bufoff(dir
->bh
, 0), sizeof(dir
->dirhead
));
425 memcpy(&dir
->dirtail
, bufoff(dir
->bh
, 2007), sizeof(dir
->dirtail
));
427 if (dir
->dirhead
.startmasseq
!= dir
->dirtail
.new.endmasseq
||
428 memcmp(&dir
->dirhead
.startname
, &dir
->dirtail
.new.endname
, 4))
431 if (memcmp(&dir
->dirhead
.startname
, "Nick", 4) &&
432 memcmp(&dir
->dirhead
.startname
, "Hugo", 4))
435 if (adfs_dir_checkbyte(dir
) != dir
->dirtail
.new.dircheckbyte
)
439 for (i
= dir
->nr_buffers
- 1; i
>= 0; i
--)
440 mark_buffer_dirty(dir
->bh
[i
]);
447 adfs_error(dir
->sb
, "whoops! I broke a directory!");
453 adfs_f_free(struct adfs_dir
*dir
)
457 for (i
= dir
->nr_buffers
- 1; i
>= 0; i
--) {
466 struct adfs_dir_ops adfs_f_dir_ops
= {