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Linux/fs/adfs/dir_f.c

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  1 /*
  2  *  linux/fs/adfs/dir_f.c
  3  *
  4  * Copyright (C) 1997-1999 Russell King
  5  *
  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.
  9  *
 10  *  E and F format directory handling
 11  */
 12 #include <linux/buffer_head.h>
 13 #include "adfs.h"
 14 #include "dir_f.h"
 15 
 16 static void adfs_f_free(struct adfs_dir *dir);
 17 
 18 /*
 19  * Read an (unaligned) value of length 1..4 bytes
 20  */
 21 static inline unsigned int adfs_readval(unsigned char *p, int len)
 22 {
 23         unsigned int val = 0;
 24 
 25         switch (len) {
 26         case 4:         val |= p[3] << 24;
 27         case 3:         val |= p[2] << 16;
 28         case 2:         val |= p[1] << 8;
 29         default:        val |= p[0];
 30         }
 31         return val;
 32 }
 33 
 34 static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
 35 {
 36         switch (len) {
 37         case 4:         p[3] = val >> 24;
 38         case 3:         p[2] = val >> 16;
 39         case 2:         p[1] = val >> 8;
 40         default:        p[0] = val;
 41         }
 42 }
 43 
 44 static inline int adfs_readname(char *buf, char *ptr, int maxlen)
 45 {
 46         char *old_buf = buf;
 47 
 48         while ((unsigned char)*ptr >= ' ' && maxlen--) {
 49                 if (*ptr == '/')
 50                         *buf++ = '.';
 51                 else
 52                         *buf++ = *ptr;
 53                 ptr++;
 54         }
 55 
 56         return buf - old_buf;
 57 }
 58 
 59 #define ror13(v) ((v >> 13) | (v << 19))
 60 
 61 #define dir_u8(idx)                             \
 62         ({ int _buf = idx >> blocksize_bits;    \
 63            int _off = idx - (_buf << blocksize_bits);\
 64           *(u8 *)(bh[_buf]->b_data + _off);     \
 65         })
 66 
 67 #define dir_u32(idx)                            \
 68         ({ int _buf = idx >> blocksize_bits;    \
 69            int _off = idx - (_buf << blocksize_bits);\
 70           *(__le32 *)(bh[_buf]->b_data + _off); \
 71         })
 72 
 73 #define bufoff(_bh,_idx)                        \
 74         ({ int _buf = _idx >> blocksize_bits;   \
 75            int _off = _idx - (_buf << blocksize_bits);\
 76           (u8 *)(_bh[_buf]->b_data + _off);     \
 77         })
 78 
 79 /*
 80  * There are some algorithms that are nice in
 81  * assembler, but a bitch in C...  This is one
 82  * of them.
 83  */
 84 static u8
 85 adfs_dir_checkbyte(const struct adfs_dir *dir)
 86 {
 87         struct buffer_head * const *bh = dir->bh;
 88         const int blocksize_bits = dir->sb->s_blocksize_bits;
 89         union { __le32 *ptr32; u8 *ptr8; } ptr, end;
 90         u32 dircheck = 0;
 91         int last = 5 - 26;
 92         int i = 0;
 93 
 94         /*
 95          * Accumulate each word up to the last whole
 96          * word of the last directory entry.  This
 97          * can spread across several buffer heads.
 98          */
 99         do {
100                 last += 26;
101                 do {
102                         dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
103 
104                         i += sizeof(u32);
105                 } while (i < (last & ~3));
106         } while (dir_u8(last) != 0);
107 
108         /*
109          * Accumulate the last few bytes.  These
110          * bytes will be within the same bh.
111          */
112         if (i != last) {
113                 ptr.ptr8 = bufoff(bh, i);
114                 end.ptr8 = ptr.ptr8 + last - i;
115 
116                 do {
117                         dircheck = *ptr.ptr8++ ^ ror13(dircheck);
118                 } while (ptr.ptr8 < end.ptr8);
119         }
120 
121         /*
122          * The directory tail is in the final bh
123          * Note that contary to the RISC OS PRMs,
124          * the first few bytes are NOT included
125          * in the check.  All bytes are in the
126          * same bh.
127          */
128         ptr.ptr8 = bufoff(bh, 2008);
129         end.ptr8 = ptr.ptr8 + 36;
130 
131         do {
132                 __le32 v = *ptr.ptr32++;
133                 dircheck = le32_to_cpu(v) ^ ror13(dircheck);
134         } while (ptr.ptr32 < end.ptr32);
135 
136         return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
137 }
138 
139 /*
140  * Read and check that a directory is valid
141  */
142 static int
143 adfs_dir_read(struct super_block *sb, unsigned long object_id,
144               unsigned int size, struct adfs_dir *dir)
145 {
146         const unsigned int blocksize_bits = sb->s_blocksize_bits;
147         int blk = 0;
148 
149         /*
150          * Directories which are not a multiple of 2048 bytes
151          * are considered bad v2 [3.6]
152          */
153         if (size & 2047)
154                 goto bad_dir;
155 
156         size >>= blocksize_bits;
157 
158         dir->nr_buffers = 0;
159         dir->sb = sb;
160 
161         for (blk = 0; blk < size; blk++) {
162                 int phys;
163 
164                 phys = __adfs_block_map(sb, object_id, blk);
165                 if (!phys) {
166                         adfs_error(sb, "dir object %lX has a hole at offset %d",
167                                    object_id, blk);
168                         goto release_buffers;
169                 }
170 
171                 dir->bh[blk] = sb_bread(sb, phys);
172                 if (!dir->bh[blk])
173                         goto release_buffers;
174         }
175 
176         memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
177         memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
178 
179         if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
180             memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
181                 goto bad_dir;
182 
183         if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
184             memcmp(&dir->dirhead.startname, "Hugo", 4))
185                 goto bad_dir;
186 
187         if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
188                 goto bad_dir;
189 
190         dir->nr_buffers = blk;
191 
192         return 0;
193 
194 bad_dir:
195         adfs_error(sb, "corrupted directory fragment %lX",
196                    object_id);
197 release_buffers:
198         for (blk -= 1; blk >= 0; blk -= 1)
199                 brelse(dir->bh[blk]);
200 
201         dir->sb = NULL;
202 
203         return -EIO;
204 }
205 
206 /*
207  * convert a disk-based directory entry to a Linux ADFS directory entry
208  */
209 static inline void
210 adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj,
211         struct adfs_direntry *de)
212 {
213         obj->name_len = adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
214         obj->file_id  = adfs_readval(de->dirinddiscadd, 3);
215         obj->loadaddr = adfs_readval(de->dirload, 4);
216         obj->execaddr = adfs_readval(de->direxec, 4);
217         obj->size     = adfs_readval(de->dirlen,  4);
218         obj->attr     = de->newdiratts;
219         obj->filetype = -1;
220 
221         /*
222          * object is a file and is filetyped and timestamped?
223          * RISC OS 12-bit filetype is stored in load_address[19:8]
224          */
225         if ((0 == (obj->attr & ADFS_NDA_DIRECTORY)) &&
226                 (0xfff00000 == (0xfff00000 & obj->loadaddr))) {
227                 obj->filetype = (__u16) ((0x000fff00 & obj->loadaddr) >> 8);
228 
229                 /* optionally append the ,xyz hex filetype suffix */
230                 if (ADFS_SB(dir->sb)->s_ftsuffix)
231                         obj->name_len +=
232                                 append_filetype_suffix(
233                                         &obj->name[obj->name_len],
234                                         obj->filetype);
235         }
236 }
237 
238 /*
239  * convert a Linux ADFS directory entry to a disk-based directory entry
240  */
241 static inline void
242 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
243 {
244         adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
245         adfs_writeval(de->dirload, 4, obj->loadaddr);
246         adfs_writeval(de->direxec, 4, obj->execaddr);
247         adfs_writeval(de->dirlen,  4, obj->size);
248         de->newdiratts = obj->attr;
249 }
250 
251 /*
252  * get a directory entry.  Note that the caller is responsible
253  * for holding the relevant locks.
254  */
255 static int
256 __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
257 {
258         struct super_block *sb = dir->sb;
259         struct adfs_direntry de;
260         int thissize, buffer, offset;
261 
262         buffer = pos >> sb->s_blocksize_bits;
263 
264         if (buffer > dir->nr_buffers)
265                 return -EINVAL;
266 
267         offset = pos & (sb->s_blocksize - 1);
268         thissize = sb->s_blocksize - offset;
269         if (thissize > 26)
270                 thissize = 26;
271 
272         memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
273         if (thissize != 26)
274                 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
275                        26 - thissize);
276 
277         if (!de.dirobname[0])
278                 return -ENOENT;
279 
280         adfs_dir2obj(dir, obj, &de);
281 
282         return 0;
283 }
284 
285 static int
286 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
287 {
288         struct super_block *sb = dir->sb;
289         struct adfs_direntry de;
290         int thissize, buffer, offset;
291 
292         buffer = pos >> sb->s_blocksize_bits;
293 
294         if (buffer > dir->nr_buffers)
295                 return -EINVAL;
296 
297         offset = pos & (sb->s_blocksize - 1);
298         thissize = sb->s_blocksize - offset;
299         if (thissize > 26)
300                 thissize = 26;
301 
302         /*
303          * Get the entry in total
304          */
305         memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
306         if (thissize != 26)
307                 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
308                        26 - thissize);
309 
310         /*
311          * update it
312          */
313         adfs_obj2dir(&de, obj);
314 
315         /*
316          * Put the new entry back
317          */
318         memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
319         if (thissize != 26)
320                 memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
321                        26 - thissize);
322 
323         return 0;
324 }
325 
326 /*
327  * the caller is responsible for holding the necessary
328  * locks.
329  */
330 static int
331 adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
332 {
333         int pos, ret;
334 
335         ret = -ENOENT;
336 
337         for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
338                 struct object_info obj;
339 
340                 if (!__adfs_dir_get(dir, pos, &obj))
341                         break;
342 
343                 if (obj.file_id == object_id) {
344                         ret = pos;
345                         break;
346                 }
347         }
348 
349         return ret;
350 }
351 
352 static int
353 adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
354 {
355         int ret;
356 
357         if (sz != ADFS_NEWDIR_SIZE)
358                 return -EIO;
359 
360         ret = adfs_dir_read(sb, id, sz, dir);
361         if (ret)
362                 adfs_error(sb, "unable to read directory");
363         else
364                 dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
365 
366         return ret;
367 }
368 
369 static int
370 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
371 {
372         if (fpos >= ADFS_NUM_DIR_ENTRIES)
373                 return -ENOENT;
374 
375         dir->pos = 5 + fpos * 26;
376         return 0;
377 }
378 
379 static int
380 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
381 {
382         unsigned int ret;
383 
384         ret = __adfs_dir_get(dir, dir->pos, obj);
385         if (ret == 0)
386                 dir->pos += 26;
387 
388         return ret;
389 }
390 
391 static int
392 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
393 {
394         struct super_block *sb = dir->sb;
395         int ret, i;
396 
397         ret = adfs_dir_find_entry(dir, obj->file_id);
398         if (ret < 0) {
399                 adfs_error(dir->sb, "unable to locate entry to update");
400                 goto out;
401         }
402 
403         __adfs_dir_put(dir, ret, obj);
404  
405         /*
406          * Increment directory sequence number
407          */
408         dir->bh[0]->b_data[0] += 1;
409         dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
410 
411         ret = adfs_dir_checkbyte(dir);
412         /*
413          * Update directory check byte
414          */
415         dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
416 
417 #if 1
418         {
419         const unsigned int blocksize_bits = sb->s_blocksize_bits;
420 
421         memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
422         memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
423 
424         if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
425             memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
426                 goto bad_dir;
427 
428         if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
429             memcmp(&dir->dirhead.startname, "Hugo", 4))
430                 goto bad_dir;
431 
432         if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
433                 goto bad_dir;
434         }
435 #endif
436         for (i = dir->nr_buffers - 1; i >= 0; i--)
437                 mark_buffer_dirty(dir->bh[i]);
438 
439         ret = 0;
440 out:
441         return ret;
442 #if 1
443 bad_dir:
444         adfs_error(dir->sb, "whoops!  I broke a directory!");
445         return -EIO;
446 #endif
447 }
448 
449 static int
450 adfs_f_sync(struct adfs_dir *dir)
451 {
452         int err = 0;
453         int i;
454 
455         for (i = dir->nr_buffers - 1; i >= 0; i--) {
456                 struct buffer_head *bh = dir->bh[i];
457                 sync_dirty_buffer(bh);
458                 if (buffer_req(bh) && !buffer_uptodate(bh))
459                         err = -EIO;
460         }
461 
462         return err;
463 }
464 
465 static void
466 adfs_f_free(struct adfs_dir *dir)
467 {
468         int i;
469 
470         for (i = dir->nr_buffers - 1; i >= 0; i--) {
471                 brelse(dir->bh[i]);
472                 dir->bh[i] = NULL;
473         }
474 
475         dir->nr_buffers = 0;
476         dir->sb = NULL;
477 }
478 
479 const struct adfs_dir_ops adfs_f_dir_ops = {
480         .read           = adfs_f_read,
481         .setpos         = adfs_f_setpos,
482         .getnext        = adfs_f_getnext,
483         .update         = adfs_f_update,
484         .sync           = adfs_f_sync,
485         .free           = adfs_f_free
486 };
487 

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