xref: /openbmc/linux/fs/adfs/dir_f.c (revision d5532ee7) 
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 	*buf = '\0';
56 
57 	return buf - old_buf;
58 }
59 
60 #define ror13(v) ((v >> 13) | (v << 19))
61 
62 #define dir_u8(idx)				\
63 	({ int _buf = idx >> blocksize_bits;	\
64 	   int _off = idx - (_buf << blocksize_bits);\
65 	  *(u8 *)(bh[_buf]->b_data + _off);	\
66 	})
67 
68 #define dir_u32(idx)				\
69 	({ int _buf = idx >> blocksize_bits;	\
70 	   int _off = idx - (_buf << blocksize_bits);\
71 	  *(__le32 *)(bh[_buf]->b_data + _off);	\
72 	})
73 
74 #define bufoff(_bh,_idx)			\
75 	({ int _buf = _idx >> blocksize_bits;	\
76 	   int _off = _idx - (_buf << blocksize_bits);\
77 	  (u8 *)(_bh[_buf]->b_data + _off);	\
78 	})
79 
80 /*
81  * There are some algorithms that are nice in
82  * assembler, but a bitch in C...  This is one
83  * of them.
84  */
85 static u8
86 adfs_dir_checkbyte(const struct adfs_dir *dir)
87 {
88 	struct buffer_head * const *bh = dir->bh;
89 	const int blocksize_bits = dir->sb->s_blocksize_bits;
90 	union { __le32 *ptr32; u8 *ptr8; } ptr, end;
91 	u32 dircheck = 0;
92 	int last = 5 - 26;
93 	int i = 0;
94 
95 	/*
96 	 * Accumulate each word up to the last whole
97 	 * word of the last directory entry.  This
98 	 * can spread across several buffer heads.
99 	 */
100 	do {
101 		last += 26;
102 		do {
103 			dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
104 
105 			i += sizeof(u32);
106 		} while (i < (last & ~3));
107 	} while (dir_u8(last) != 0);
108 
109 	/*
110 	 * Accumulate the last few bytes.  These
111 	 * bytes will be within the same bh.
112 	 */
113 	if (i != last) {
114 		ptr.ptr8 = bufoff(bh, i);
115 		end.ptr8 = ptr.ptr8 + last - i;
116 
117 		do {
118 			dircheck = *ptr.ptr8++ ^ ror13(dircheck);
119 		} while (ptr.ptr8 < end.ptr8);
120 	}
121 
122 	/*
123 	 * The directory tail is in the final bh
124 	 * Note that contary to the RISC OS PRMs,
125 	 * the first few bytes are NOT included
126 	 * in the check.  All bytes are in the
127 	 * same bh.
128 	 */
129 	ptr.ptr8 = bufoff(bh, 2008);
130 	end.ptr8 = ptr.ptr8 + 36;
131 
132 	do {
133 		__le32 v = *ptr.ptr32++;
134 		dircheck = le32_to_cpu(v) ^ ror13(dircheck);
135 	} while (ptr.ptr32 < end.ptr32);
136 
137 	return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
138 }
139 
140 /*
141  * Read and check that a directory is valid
142  */
143 static int
144 adfs_dir_read(struct super_block *sb, unsigned long object_id,
145 	      unsigned int size, struct adfs_dir *dir)
146 {
147 	const unsigned int blocksize_bits = sb->s_blocksize_bits;
148 	int blk = 0;
149 
150 	/*
151 	 * Directories which are not a multiple of 2048 bytes
152 	 * are considered bad v2 [3.6]
153 	 */
154 	if (size & 2047)
155 		goto bad_dir;
156 
157 	size >>= blocksize_bits;
158 
159 	dir->nr_buffers = 0;
160 	dir->sb = sb;
161 
162 	for (blk = 0; blk < size; blk++) {
163 		int phys;
164 
165 		phys = __adfs_block_map(sb, object_id, blk);
166 		if (!phys) {
167 			adfs_error(sb, "dir object %lX has a hole at offset %d",
168 				   object_id, blk);
169 			goto release_buffers;
170 		}
171 
172 		dir->bh[blk] = sb_bread(sb, phys);
173 		if (!dir->bh[blk])
174 			goto release_buffers;
175 	}
176 
177 	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
178 	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
179 
180 	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
181 	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
182 		goto bad_dir;
183 
184 	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
185 	    memcmp(&dir->dirhead.startname, "Hugo", 4))
186 		goto bad_dir;
187 
188 	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
189 		goto bad_dir;
190 
191 	dir->nr_buffers = blk;
192 
193 	return 0;
194 
195 bad_dir:
196 	adfs_error(sb, "corrupted directory fragment %lX",
197 		   object_id);
198 release_buffers:
199 	for (blk -= 1; blk >= 0; blk -= 1)
200 		brelse(dir->bh[blk]);
201 
202 	dir->sb = NULL;
203 
204 	return -EIO;
205 }
206 
207 /*
208  * convert a disk-based directory entry to a Linux ADFS directory entry
209  */
210 static inline void
211 adfs_dir2obj(struct object_info *obj, 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 }
220 
221 /*
222  * convert a Linux ADFS directory entry to a disk-based directory entry
223  */
224 static inline void
225 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
226 {
227 	adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
228 	adfs_writeval(de->dirload, 4, obj->loadaddr);
229 	adfs_writeval(de->direxec, 4, obj->execaddr);
230 	adfs_writeval(de->dirlen,  4, obj->size);
231 	de->newdiratts = obj->attr;
232 }
233 
234 /*
235  * get a directory entry.  Note that the caller is responsible
236  * for holding the relevant locks.
237  */
238 static int
239 __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
240 {
241 	struct super_block *sb = dir->sb;
242 	struct adfs_direntry de;
243 	int thissize, buffer, offset;
244 
245 	buffer = pos >> sb->s_blocksize_bits;
246 
247 	if (buffer > dir->nr_buffers)
248 		return -EINVAL;
249 
250 	offset = pos & (sb->s_blocksize - 1);
251 	thissize = sb->s_blocksize - offset;
252 	if (thissize > 26)
253 		thissize = 26;
254 
255 	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
256 	if (thissize != 26)
257 		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
258 		       26 - thissize);
259 
260 	if (!de.dirobname[0])
261 		return -ENOENT;
262 
263 	adfs_dir2obj(obj, &de);
264 
265 	return 0;
266 }
267 
268 static int
269 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
270 {
271 	struct super_block *sb = dir->sb;
272 	struct adfs_direntry de;
273 	int thissize, buffer, offset;
274 
275 	buffer = pos >> sb->s_blocksize_bits;
276 
277 	if (buffer > dir->nr_buffers)
278 		return -EINVAL;
279 
280 	offset = pos & (sb->s_blocksize - 1);
281 	thissize = sb->s_blocksize - offset;
282 	if (thissize > 26)
283 		thissize = 26;
284 
285 	/*
286 	 * Get the entry in total
287 	 */
288 	memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
289 	if (thissize != 26)
290 		memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
291 		       26 - thissize);
292 
293 	/*
294 	 * update it
295 	 */
296 	adfs_obj2dir(&de, obj);
297 
298 	/*
299 	 * Put the new entry back
300 	 */
301 	memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
302 	if (thissize != 26)
303 		memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
304 		       26 - thissize);
305 
306 	return 0;
307 }
308 
309 /*
310  * the caller is responsible for holding the necessary
311  * locks.
312  */
313 static int
314 adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
315 {
316 	int pos, ret;
317 
318 	ret = -ENOENT;
319 
320 	for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
321 		struct object_info obj;
322 
323 		if (!__adfs_dir_get(dir, pos, &obj))
324 			break;
325 
326 		if (obj.file_id == object_id) {
327 			ret = pos;
328 			break;
329 		}
330 	}
331 
332 	return ret;
333 }
334 
335 static int
336 adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
337 {
338 	int ret;
339 
340 	if (sz != ADFS_NEWDIR_SIZE)
341 		return -EIO;
342 
343 	ret = adfs_dir_read(sb, id, sz, dir);
344 	if (ret)
345 		adfs_error(sb, "unable to read directory");
346 	else
347 		dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
348 
349 	return ret;
350 }
351 
352 static int
353 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
354 {
355 	if (fpos >= ADFS_NUM_DIR_ENTRIES)
356 		return -ENOENT;
357 
358 	dir->pos = 5 + fpos * 26;
359 	return 0;
360 }
361 
362 static int
363 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
364 {
365 	unsigned int ret;
366 
367 	ret = __adfs_dir_get(dir, dir->pos, obj);
368 	if (ret == 0)
369 		dir->pos += 26;
370 
371 	return ret;
372 }
373 
374 static int
375 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
376 {
377 	struct super_block *sb = dir->sb;
378 	int ret, i;
379 
380 	ret = adfs_dir_find_entry(dir, obj->file_id);
381 	if (ret < 0) {
382 		adfs_error(dir->sb, "unable to locate entry to update");
383 		goto out;
384 	}
385 
386 	__adfs_dir_put(dir, ret, obj);
387 
388 	/*
389 	 * Increment directory sequence number
390 	 */
391 	dir->bh[0]->b_data[0] += 1;
392 	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
393 
394 	ret = adfs_dir_checkbyte(dir);
395 	/*
396 	 * Update directory check byte
397 	 */
398 	dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
399 
400 #if 1
401 	{
402 	const unsigned int blocksize_bits = sb->s_blocksize_bits;
403 
404 	memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
405 	memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
406 
407 	if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
408 	    memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
409 		goto bad_dir;
410 
411 	if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
412 	    memcmp(&dir->dirhead.startname, "Hugo", 4))
413 		goto bad_dir;
414 
415 	if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
416 		goto bad_dir;
417 	}
418 #endif
419 	for (i = dir->nr_buffers - 1; i >= 0; i--)
420 		mark_buffer_dirty(dir->bh[i]);
421 
422 	ret = 0;
423 out:
424 	return ret;
425 #if 1
426 bad_dir:
427 	adfs_error(dir->sb, "whoops!  I broke a directory!");
428 	return -EIO;
429 #endif
430 }
431 
432 static int
433 adfs_f_sync(struct adfs_dir *dir)
434 {
435 	int err = 0;
436 	int i;
437 
438 	for (i = dir->nr_buffers - 1; i >= 0; i--) {
439 		struct buffer_head *bh = dir->bh[i];
440 		sync_dirty_buffer(bh);
441 		if (buffer_req(bh) && !buffer_uptodate(bh))
442 			err = -EIO;
443 	}
444 
445 	return err;
446 }
447 
448 static void
449 adfs_f_free(struct adfs_dir *dir)
450 {
451 	int i;
452 
453 	for (i = dir->nr_buffers - 1; i >= 0; i--) {
454 		brelse(dir->bh[i]);
455 		dir->bh[i] = NULL;
456 	}
457 
458 	dir->nr_buffers = 0;
459 	dir->sb = NULL;
460 }
461 
462 struct adfs_dir_ops adfs_f_dir_ops = {
463 	.read		= adfs_f_read,
464 	.setpos		= adfs_f_setpos,
465 	.getnext	= adfs_f_getnext,
466 	.update		= adfs_f_update,
467 	.sync		= adfs_f_sync,
468 	.free		= adfs_f_free
469 };
470