1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/fs/adfs/dir_f.c
5 * Copyright (C) 1997-1999 Russell King
7 * E and F format directory handling
12 static void adfs_f_free(struct adfs_dir *dir);
15 * Read an (unaligned) value of length 1..4 bytes
17 static inline unsigned int adfs_readval(unsigned char *p, int len)
22 case 4: val |= p[3] << 24;
24 case 3: val |= p[2] << 16;
26 case 2: val |= p[1] << 8;
33 static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
36 case 4: p[3] = val >> 24;
38 case 3: p[2] = val >> 16;
40 case 2: p[1] = val >> 8;
46 #define ror13(v) ((v >> 13) | (v << 19))
49 ({ int _buf = idx >> blocksize_bits; \
50 int _off = idx - (_buf << blocksize_bits);\
51 *(u8 *)(bh[_buf]->b_data + _off); \
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); \
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); \
67 * There are some algorithms that are nice in
68 * assembler, but a bitch in C... This is one
72 adfs_dir_checkbyte(const struct adfs_dir *dir)
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;
82 * Accumulate each word up to the last whole
83 * word of the last directory entry. This
84 * can spread across several buffer heads.
89 dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
92 } while (i < (last & ~3));
93 } while (dir_u8(last) != 0);
96 * Accumulate the last few bytes. These
97 * bytes will be within the same bh.
100 ptr.ptr8 = bufoff(bh, i);
101 end.ptr8 = ptr.ptr8 + last - i;
104 dircheck = *ptr.ptr8++ ^ ror13(dircheck);
105 } while (ptr.ptr8 < end.ptr8);
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
115 ptr.ptr8 = bufoff(bh, 2008);
116 end.ptr8 = ptr.ptr8 + 36;
119 __le32 v = *ptr.ptr32++;
120 dircheck = le32_to_cpu(v) ^ ror13(dircheck);
121 } while (ptr.ptr32 < end.ptr32);
123 return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
126 /* Read and check that a directory is valid */
127 static int adfs_dir_read(struct super_block *sb, u32 indaddr,
128 unsigned int size, struct adfs_dir *dir)
130 const unsigned int blocksize_bits = sb->s_blocksize_bits;
134 * Directories which are not a multiple of 2048 bytes
135 * are considered bad v2 [3.6]
140 size >>= blocksize_bits;
145 for (blk = 0; blk < size; blk++) {
148 phys = __adfs_block_map(sb, indaddr, blk);
150 adfs_error(sb, "dir %06x has a hole at offset %d",
152 goto release_buffers;
155 dir->bh[blk] = sb_bread(sb, phys);
157 goto release_buffers;
160 memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
161 memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
163 if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
164 memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
167 if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
168 memcmp(&dir->dirhead.startname, "Hugo", 4))
171 if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
174 dir->nr_buffers = blk;
179 adfs_error(sb, "dir %06x is corrupted", indaddr);
181 for (blk -= 1; blk >= 0; blk -= 1)
182 brelse(dir->bh[blk]);
190 * convert a disk-based directory entry to a Linux ADFS directory entry
193 adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj,
194 struct adfs_direntry *de)
196 unsigned int name_len;
198 for (name_len = 0; name_len < ADFS_F_NAME_LEN; name_len++) {
199 if (de->dirobname[name_len] < ' ')
202 obj->name[name_len] = de->dirobname[name_len];
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;
212 adfs_object_fixup(dir, obj);
216 * convert a Linux ADFS directory entry to a disk-based directory entry
219 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
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;
229 * get a directory entry. Note that the caller is responsible
230 * for holding the relevant locks.
233 __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
235 struct super_block *sb = dir->sb;
236 struct adfs_direntry de;
237 int thissize, buffer, offset;
239 buffer = pos >> sb->s_blocksize_bits;
241 if (buffer > dir->nr_buffers)
244 offset = pos & (sb->s_blocksize - 1);
245 thissize = sb->s_blocksize - offset;
249 memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
251 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
254 if (!de.dirobname[0])
257 adfs_dir2obj(dir, obj, &de);
263 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
265 struct super_block *sb = dir->sb;
266 struct adfs_direntry de;
267 int thissize, buffer, offset;
269 buffer = pos >> sb->s_blocksize_bits;
271 if (buffer > dir->nr_buffers)
274 offset = pos & (sb->s_blocksize - 1);
275 thissize = sb->s_blocksize - offset;
280 * Get the entry in total
282 memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
284 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
290 adfs_obj2dir(&de, obj);
293 * Put the new entry back
295 memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
297 memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
304 * the caller is responsible for holding the necessary
307 static int adfs_dir_find_entry(struct adfs_dir *dir, u32 indaddr)
313 for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
314 struct object_info obj;
316 if (!__adfs_dir_get(dir, pos, &obj))
319 if (obj.indaddr == indaddr) {
328 static int adfs_f_read(struct super_block *sb, u32 indaddr, unsigned int size,
329 struct adfs_dir *dir)
333 if (size != ADFS_NEWDIR_SIZE)
336 ret = adfs_dir_read(sb, indaddr, size, dir);
338 adfs_error(sb, "unable to read directory");
340 dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
346 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
348 if (fpos >= ADFS_NUM_DIR_ENTRIES)
351 dir->pos = 5 + fpos * 26;
356 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
360 ret = __adfs_dir_get(dir, dir->pos, obj);
368 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
370 struct super_block *sb = dir->sb;
373 ret = adfs_dir_find_entry(dir, obj->indaddr);
375 adfs_error(dir->sb, "unable to locate entry to update");
379 __adfs_dir_put(dir, ret, obj);
382 * Increment directory sequence number
384 dir->bh[0]->b_data[0] += 1;
385 dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
387 ret = adfs_dir_checkbyte(dir);
389 * Update directory check byte
391 dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
395 const unsigned int blocksize_bits = sb->s_blocksize_bits;
397 memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
398 memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
400 if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
401 memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
404 if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
405 memcmp(&dir->dirhead.startname, "Hugo", 4))
408 if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
412 for (i = dir->nr_buffers - 1; i >= 0; i--)
413 mark_buffer_dirty(dir->bh[i]);
420 adfs_error(dir->sb, "whoops! I broke a directory!");
426 adfs_f_sync(struct adfs_dir *dir)
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))
442 adfs_f_free(struct adfs_dir *dir)
446 for (i = dir->nr_buffers - 1; i >= 0; i--) {
455 const struct adfs_dir_ops adfs_f_dir_ops = {
457 .setpos = adfs_f_setpos,
458 .getnext = adfs_f_getnext,
459 .update = adfs_f_update,