2 * linux/fs/adfs/dir_f.c
4 * Copyright (C) 1997-1999 Russell King
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.
10 * E and F format directory handling
12 #include <linux/errno.h>
14 #include <linux/adfs_fs.h>
15 #include <linux/time.h>
16 #include <linux/stat.h>
17 #include <linux/spinlock.h>
18 #include <linux/buffer_head.h>
19 #include <linux/string.h>
24 static void adfs_f_free(struct adfs_dir *dir);
27 * Read an (unaligned) value of length 1..4 bytes
29 static inline unsigned int adfs_readval(unsigned char *p, int len)
34 case 4: val |= p[3] << 24;
35 case 3: val |= p[2] << 16;
36 case 2: val |= p[1] << 8;
42 static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
45 case 4: p[3] = val >> 24;
46 case 3: p[2] = val >> 16;
47 case 2: p[1] = val >> 8;
52 static inline int adfs_readname(char *buf, char *ptr, int maxlen)
56 while (*ptr >= ' ' && maxlen--) {
68 static inline void adfs_writename(char *to, char *from, int maxlen)
72 for (i = 0; i < maxlen; i++) {
81 for (; i < maxlen; i++)
85 #define ror13(v) ((v >> 13) | (v << 19))
88 ({ int _buf = idx >> blocksize_bits; \
89 int _off = idx - (_buf << blocksize_bits);\
90 *(u8 *)(bh[_buf]->b_data + _off); \
93 #define dir_u32(idx) \
94 ({ int _buf = idx >> blocksize_bits; \
95 int _off = idx - (_buf << blocksize_bits);\
96 *(__le32 *)(bh[_buf]->b_data + _off); \
99 #define bufoff(_bh,_idx) \
100 ({ int _buf = _idx >> blocksize_bits; \
101 int _off = _idx - (_buf << blocksize_bits);\
102 (u8 *)(_bh[_buf]->b_data + _off); \
106 * There are some algorithms that are nice in
107 * assembler, but a bitch in C... This is one
111 adfs_dir_checkbyte(const struct adfs_dir *dir)
113 struct buffer_head * const *bh = dir->bh;
114 const int blocksize_bits = dir->sb->s_blocksize_bits;
115 union { __le32 *ptr32; u8 *ptr8; } ptr, end;
121 * Accumulate each word up to the last whole
122 * word of the last directory entry. This
123 * can spread across several buffer heads.
128 dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
131 } while (i < (last & ~3));
132 } while (dir_u8(last) != 0);
135 * Accumulate the last few bytes. These
136 * bytes will be within the same bh.
139 ptr.ptr8 = bufoff(bh, i);
140 end.ptr8 = ptr.ptr8 + last - i;
143 dircheck = *ptr.ptr8++ ^ ror13(dircheck);
144 while (ptr.ptr8 < end.ptr8);
148 * The directory tail is in the final bh
149 * Note that contary to the RISC OS PRMs,
150 * the first few bytes are NOT included
151 * in the check. All bytes are in the
154 ptr.ptr8 = bufoff(bh, 2008);
155 end.ptr8 = ptr.ptr8 + 36;
158 __le32 v = *ptr.ptr32++;
159 dircheck = le32_to_cpu(v) ^ ror13(dircheck);
160 } while (ptr.ptr32 < end.ptr32);
162 return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
166 * Read and check that a directory is valid
169 adfs_dir_read(struct super_block *sb, unsigned long object_id,
170 unsigned int size, struct adfs_dir *dir)
172 const unsigned int blocksize_bits = sb->s_blocksize_bits;
176 * Directories which are not a multiple of 2048 bytes
177 * are considered bad v2 [3.6]
182 size >>= blocksize_bits;
187 for (blk = 0; blk < size; blk++) {
190 phys = __adfs_block_map(sb, object_id, blk);
192 adfs_error(sb, "dir object %lX has a hole at offset %d",
194 goto release_buffers;
197 dir->bh[blk] = sb_bread(sb, phys);
199 goto release_buffers;
202 memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
203 memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
205 if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
206 memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
209 if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
210 memcmp(&dir->dirhead.startname, "Hugo", 4))
213 if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
216 dir->nr_buffers = blk;
221 adfs_error(sb, "corrupted directory fragment %lX",
224 for (blk -= 1; blk >= 0; blk -= 1)
225 brelse(dir->bh[blk]);
233 * convert a disk-based directory entry to a Linux ADFS directory entry
236 adfs_dir2obj(struct object_info *obj, struct adfs_direntry *de)
238 obj->name_len = adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
239 obj->file_id = adfs_readval(de->dirinddiscadd, 3);
240 obj->loadaddr = adfs_readval(de->dirload, 4);
241 obj->execaddr = adfs_readval(de->direxec, 4);
242 obj->size = adfs_readval(de->dirlen, 4);
243 obj->attr = de->newdiratts;
247 * convert a Linux ADFS directory entry to a disk-based directory entry
250 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
252 adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
253 adfs_writeval(de->dirload, 4, obj->loadaddr);
254 adfs_writeval(de->direxec, 4, obj->execaddr);
255 adfs_writeval(de->dirlen, 4, obj->size);
256 de->newdiratts = obj->attr;
260 * get a directory entry. Note that the caller is responsible
261 * for holding the relevant locks.
264 __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
266 struct super_block *sb = dir->sb;
267 struct adfs_direntry de;
268 int thissize, buffer, offset;
270 buffer = pos >> sb->s_blocksize_bits;
272 if (buffer > dir->nr_buffers)
275 offset = pos & (sb->s_blocksize - 1);
276 thissize = sb->s_blocksize - offset;
280 memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
282 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
285 if (!de.dirobname[0])
288 adfs_dir2obj(obj, &de);
294 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
296 struct super_block *sb = dir->sb;
297 struct adfs_direntry de;
298 int thissize, buffer, offset;
300 buffer = pos >> sb->s_blocksize_bits;
302 if (buffer > dir->nr_buffers)
305 offset = pos & (sb->s_blocksize - 1);
306 thissize = sb->s_blocksize - offset;
311 * Get the entry in total
313 memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
315 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
321 adfs_obj2dir(&de, obj);
324 * Put the new entry back
326 memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
328 memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
335 * the caller is responsible for holding the necessary
339 adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
345 for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
346 struct object_info obj;
348 if (!__adfs_dir_get(dir, pos, &obj))
351 if (obj.file_id == object_id) {
361 adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
365 if (sz != ADFS_NEWDIR_SIZE)
368 ret = adfs_dir_read(sb, id, sz, dir);
370 adfs_error(sb, "unable to read directory");
372 dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
378 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
380 if (fpos >= ADFS_NUM_DIR_ENTRIES)
383 dir->pos = 5 + fpos * 26;
388 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
392 ret = __adfs_dir_get(dir, dir->pos, obj);
400 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
402 struct super_block *sb = dir->sb;
405 ret = adfs_dir_find_entry(dir, obj->file_id);
407 adfs_error(dir->sb, "unable to locate entry to update");
411 __adfs_dir_put(dir, ret, obj);
414 * Increment directory sequence number
416 dir->bh[0]->b_data[0] += 1;
417 dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
419 ret = adfs_dir_checkbyte(dir);
421 * Update directory check byte
423 dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
427 const unsigned int blocksize_bits = sb->s_blocksize_bits;
429 memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
430 memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
432 if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
433 memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
436 if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
437 memcmp(&dir->dirhead.startname, "Hugo", 4))
440 if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
444 for (i = dir->nr_buffers - 1; i >= 0; i--)
445 mark_buffer_dirty(dir->bh[i]);
452 adfs_error(dir->sb, "whoops! I broke a directory!");
458 adfs_f_free(struct adfs_dir *dir)
462 for (i = dir->nr_buffers - 1; i >= 0; i--) {
471 struct adfs_dir_ops adfs_f_dir_ops = {
473 .setpos = adfs_f_setpos,
474 .getnext = adfs_f_getnext,
475 .update = adfs_f_update,