Commit | Line | Data |
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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/fs/adfs/dir_f.c | |
4 | * | |
5 | * Copyright (C) 1997-1999 Russell King | |
6 | * | |
1da177e4 LT |
7 | * E and F format directory handling |
8 | */ | |
1da177e4 LT |
9 | #include "adfs.h" |
10 | #include "dir_f.h" | |
11 | ||
1da177e4 LT |
12 | /* |
13 | * Read an (unaligned) value of length 1..4 bytes | |
14 | */ | |
15 | static inline unsigned int adfs_readval(unsigned char *p, int len) | |
16 | { | |
17 | unsigned int val = 0; | |
18 | ||
19 | switch (len) { | |
20 | case 4: val |= p[3] << 24; | |
df561f66 | 21 | fallthrough; |
1da177e4 | 22 | case 3: val |= p[2] << 16; |
df561f66 | 23 | fallthrough; |
1da177e4 | 24 | case 2: val |= p[1] << 8; |
df561f66 | 25 | fallthrough; |
1da177e4 LT |
26 | default: val |= p[0]; |
27 | } | |
28 | return val; | |
29 | } | |
30 | ||
31 | static inline void adfs_writeval(unsigned char *p, int len, unsigned int val) | |
32 | { | |
33 | switch (len) { | |
34 | case 4: p[3] = val >> 24; | |
df561f66 | 35 | fallthrough; |
1da177e4 | 36 | case 3: p[2] = val >> 16; |
df561f66 | 37 | fallthrough; |
1da177e4 | 38 | case 2: p[1] = val >> 8; |
df561f66 | 39 | fallthrough; |
1da177e4 LT |
40 | default: p[0] = val; |
41 | } | |
42 | } | |
43 | ||
1da177e4 LT |
44 | #define ror13(v) ((v >> 13) | (v << 19)) |
45 | ||
46 | #define dir_u8(idx) \ | |
47 | ({ int _buf = idx >> blocksize_bits; \ | |
48 | int _off = idx - (_buf << blocksize_bits);\ | |
49 | *(u8 *)(bh[_buf]->b_data + _off); \ | |
50 | }) | |
51 | ||
52 | #define dir_u32(idx) \ | |
53 | ({ int _buf = idx >> blocksize_bits; \ | |
54 | int _off = idx - (_buf << blocksize_bits);\ | |
55 | *(__le32 *)(bh[_buf]->b_data + _off); \ | |
56 | }) | |
57 | ||
58 | #define bufoff(_bh,_idx) \ | |
59 | ({ int _buf = _idx >> blocksize_bits; \ | |
60 | int _off = _idx - (_buf << blocksize_bits);\ | |
016936b3 | 61 | (void *)(_bh[_buf]->b_data + _off); \ |
1da177e4 LT |
62 | }) |
63 | ||
64 | /* | |
65 | * There are some algorithms that are nice in | |
66 | * assembler, but a bitch in C... This is one | |
67 | * of them. | |
68 | */ | |
69 | static u8 | |
70 | adfs_dir_checkbyte(const struct adfs_dir *dir) | |
71 | { | |
72 | struct buffer_head * const *bh = dir->bh; | |
73 | const int blocksize_bits = dir->sb->s_blocksize_bits; | |
74 | union { __le32 *ptr32; u8 *ptr8; } ptr, end; | |
75 | u32 dircheck = 0; | |
76 | int last = 5 - 26; | |
77 | int i = 0; | |
78 | ||
79 | /* | |
80 | * Accumulate each word up to the last whole | |
81 | * word of the last directory entry. This | |
82 | * can spread across several buffer heads. | |
83 | */ | |
84 | do { | |
85 | last += 26; | |
86 | do { | |
87 | dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck); | |
88 | ||
89 | i += sizeof(u32); | |
90 | } while (i < (last & ~3)); | |
91 | } while (dir_u8(last) != 0); | |
92 | ||
93 | /* | |
94 | * Accumulate the last few bytes. These | |
95 | * bytes will be within the same bh. | |
96 | */ | |
97 | if (i != last) { | |
98 | ptr.ptr8 = bufoff(bh, i); | |
99 | end.ptr8 = ptr.ptr8 + last - i; | |
100 | ||
e5949050 | 101 | do { |
1da177e4 | 102 | dircheck = *ptr.ptr8++ ^ ror13(dircheck); |
e5949050 | 103 | } while (ptr.ptr8 < end.ptr8); |
1da177e4 LT |
104 | } |
105 | ||
106 | /* | |
107 | * The directory tail is in the final bh | |
108 | * Note that contary to the RISC OS PRMs, | |
109 | * the first few bytes are NOT included | |
110 | * in the check. All bytes are in the | |
111 | * same bh. | |
112 | */ | |
113 | ptr.ptr8 = bufoff(bh, 2008); | |
114 | end.ptr8 = ptr.ptr8 + 36; | |
115 | ||
116 | do { | |
117 | __le32 v = *ptr.ptr32++; | |
118 | dircheck = le32_to_cpu(v) ^ ror13(dircheck); | |
119 | } while (ptr.ptr32 < end.ptr32); | |
120 | ||
121 | return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff; | |
122 | } | |
123 | ||
ffc8df34 RK |
124 | static int adfs_f_validate(struct adfs_dir *dir) |
125 | { | |
126 | struct adfs_dirheader *head = dir->dirhead; | |
127 | struct adfs_newdirtail *tail = dir->newtail; | |
128 | ||
129 | if (head->startmasseq != tail->endmasseq || | |
7a0e4048 | 130 | tail->dirlastmask || tail->reserved[0] || tail->reserved[1] || |
ffc8df34 RK |
131 | (memcmp(&head->startname, "Nick", 4) && |
132 | memcmp(&head->startname, "Hugo", 4)) || | |
133 | memcmp(&head->startname, &tail->endname, 4) || | |
134 | adfs_dir_checkbyte(dir) != tail->dircheckbyte) | |
135 | return -EIO; | |
136 | ||
137 | return 0; | |
138 | } | |
139 | ||
5ed70bb4 | 140 | /* Read and check that a directory is valid */ |
9318731b RK |
141 | static int adfs_f_read(struct super_block *sb, u32 indaddr, unsigned int size, |
142 | struct adfs_dir *dir) | |
1da177e4 LT |
143 | { |
144 | const unsigned int blocksize_bits = sb->s_blocksize_bits; | |
419a6e5e | 145 | int ret; |
1da177e4 | 146 | |
9318731b RK |
147 | if (size && size != ADFS_NEWDIR_SIZE) |
148 | return -EIO; | |
1da177e4 | 149 | |
9318731b | 150 | ret = adfs_dir_read_buffers(sb, indaddr, ADFS_NEWDIR_SIZE, dir); |
419a6e5e RK |
151 | if (ret) |
152 | return ret; | |
1da177e4 | 153 | |
016936b3 RK |
154 | dir->dirhead = bufoff(dir->bh, 0); |
155 | dir->newtail = bufoff(dir->bh, 2007); | |
1da177e4 | 156 | |
ffc8df34 | 157 | if (adfs_f_validate(dir)) |
1da177e4 LT |
158 | goto bad_dir; |
159 | ||
9318731b RK |
160 | dir->parent_id = adfs_readval(dir->newtail->dirparent, 3); |
161 | ||
1da177e4 LT |
162 | return 0; |
163 | ||
164 | bad_dir: | |
5ed70bb4 | 165 | adfs_error(sb, "dir %06x is corrupted", indaddr); |
1dd9f5ba | 166 | adfs_dir_relse(dir); |
1da177e4 LT |
167 | |
168 | return -EIO; | |
169 | } | |
170 | ||
171 | /* | |
172 | * convert a disk-based directory entry to a Linux ADFS directory entry | |
173 | */ | |
174 | static inline void | |
da23ef05 SS |
175 | adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj, |
176 | struct adfs_direntry *de) | |
1da177e4 | 177 | { |
adb514a4 RK |
178 | unsigned int name_len; |
179 | ||
180 | for (name_len = 0; name_len < ADFS_F_NAME_LEN; name_len++) { | |
181 | if (de->dirobname[name_len] < ' ') | |
182 | break; | |
183 | ||
184 | obj->name[name_len] = de->dirobname[name_len]; | |
185 | } | |
186 | ||
187 | obj->name_len = name_len; | |
5ed70bb4 | 188 | obj->indaddr = adfs_readval(de->dirinddiscadd, 3); |
1da177e4 LT |
189 | obj->loadaddr = adfs_readval(de->dirload, 4); |
190 | obj->execaddr = adfs_readval(de->direxec, 4); | |
191 | obj->size = adfs_readval(de->dirlen, 4); | |
192 | obj->attr = de->newdiratts; | |
da23ef05 | 193 | |
411c49bc | 194 | adfs_object_fixup(dir, obj); |
1da177e4 LT |
195 | } |
196 | ||
197 | /* | |
198 | * convert a Linux ADFS directory entry to a disk-based directory entry | |
199 | */ | |
200 | static inline void | |
201 | adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj) | |
202 | { | |
5ed70bb4 | 203 | adfs_writeval(de->dirinddiscadd, 3, obj->indaddr); |
1da177e4 LT |
204 | adfs_writeval(de->dirload, 4, obj->loadaddr); |
205 | adfs_writeval(de->direxec, 4, obj->execaddr); | |
206 | adfs_writeval(de->dirlen, 4, obj->size); | |
207 | de->newdiratts = obj->attr; | |
208 | } | |
209 | ||
210 | /* | |
211 | * get a directory entry. Note that the caller is responsible | |
212 | * for holding the relevant locks. | |
213 | */ | |
214 | static int | |
215 | __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj) | |
216 | { | |
1da177e4 | 217 | struct adfs_direntry de; |
a317120b | 218 | int ret; |
1da177e4 | 219 | |
a317120b RK |
220 | ret = adfs_dir_copyfrom(&de, dir, pos, 26); |
221 | if (ret) | |
222 | return ret; | |
1da177e4 LT |
223 | |
224 | if (!de.dirobname[0]) | |
225 | return -ENOENT; | |
226 | ||
da23ef05 | 227 | adfs_dir2obj(dir, obj, &de); |
1da177e4 LT |
228 | |
229 | return 0; | |
230 | } | |
231 | ||
1da177e4 LT |
232 | static int |
233 | adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos) | |
234 | { | |
235 | if (fpos >= ADFS_NUM_DIR_ENTRIES) | |
236 | return -ENOENT; | |
237 | ||
238 | dir->pos = 5 + fpos * 26; | |
239 | return 0; | |
240 | } | |
241 | ||
242 | static int | |
243 | adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj) | |
244 | { | |
245 | unsigned int ret; | |
246 | ||
247 | ret = __adfs_dir_get(dir, dir->pos, obj); | |
248 | if (ret == 0) | |
249 | dir->pos += 26; | |
250 | ||
251 | return ret; | |
252 | } | |
253 | ||
4287e4de RK |
254 | static int adfs_f_iterate(struct adfs_dir *dir, struct dir_context *ctx) |
255 | { | |
256 | struct object_info obj; | |
257 | int pos = 5 + (ctx->pos - 2) * 26; | |
258 | ||
259 | while (ctx->pos < 2 + ADFS_NUM_DIR_ENTRIES) { | |
260 | if (__adfs_dir_get(dir, pos, &obj)) | |
261 | break; | |
262 | if (!dir_emit(ctx, obj.name, obj.name_len, | |
263 | obj.indaddr, DT_UNKNOWN)) | |
264 | break; | |
265 | pos += 26; | |
266 | ctx->pos++; | |
267 | } | |
268 | return 0; | |
269 | } | |
270 | ||
cc625ccd | 271 | static int adfs_f_update(struct adfs_dir *dir, struct object_info *obj) |
1da177e4 | 272 | { |
cc625ccd RK |
273 | struct adfs_direntry de; |
274 | int offset, ret; | |
1da177e4 | 275 | |
cc625ccd RK |
276 | offset = 5 - (int)sizeof(de); |
277 | ||
278 | do { | |
279 | offset += sizeof(de); | |
280 | ret = adfs_dir_copyfrom(&de, dir, offset, sizeof(de)); | |
281 | if (ret) { | |
282 | adfs_error(dir->sb, "error reading directory entry"); | |
283 | return -ENOENT; | |
284 | } | |
285 | if (!de.dirobname[0]) { | |
286 | adfs_error(dir->sb, "unable to locate entry to update"); | |
287 | return -ENOENT; | |
288 | } | |
289 | } while (adfs_readval(de.dirinddiscadd, 3) != obj->indaddr); | |
290 | ||
291 | /* Update the directory entry with the new object state */ | |
292 | adfs_obj2dir(&de, obj); | |
1da177e4 | 293 | |
cc625ccd | 294 | /* Write the directory entry back to the directory */ |
aacc954c RK |
295 | return adfs_dir_copyto(dir, offset, &de, 26); |
296 | } | |
297 | ||
298 | static int adfs_f_commit(struct adfs_dir *dir) | |
299 | { | |
300 | int ret; | |
301 | ||
302 | /* Increment directory sequence number */ | |
016936b3 RK |
303 | dir->dirhead->startmasseq += 1; |
304 | dir->newtail->endmasseq += 1; | |
1da177e4 | 305 | |
aacc954c RK |
306 | /* Update directory check byte */ |
307 | dir->newtail->dircheckbyte = adfs_dir_checkbyte(dir); | |
1da177e4 | 308 | |
aacc954c | 309 | /* Make sure the directory still validates correctly */ |
ffc8df34 RK |
310 | ret = adfs_f_validate(dir); |
311 | if (ret) | |
aacc954c | 312 | adfs_msg(dir->sb, KERN_ERR, "error: update broke directory"); |
1da177e4 | 313 | |
1da177e4 | 314 | return ret; |
1da177e4 LT |
315 | } |
316 | ||
0125f504 | 317 | const struct adfs_dir_ops adfs_f_dir_ops = { |
1da177e4 | 318 | .read = adfs_f_read, |
4287e4de | 319 | .iterate = adfs_f_iterate, |
1da177e4 LT |
320 | .setpos = adfs_f_setpos, |
321 | .getnext = adfs_f_getnext, | |
322 | .update = adfs_f_update, | |
aacc954c | 323 | .commit = adfs_f_commit, |
1da177e4 | 324 | }; |