summaryrefslogtreecommitdiff
path: root/lib/tdb/common/io.c
blob: 11dfefd102b68cdb924680c5c0d94ebe8bf0d734 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
 /*
   Unix SMB/CIFS implementation.

   trivial database library

   Copyright (C) Andrew Tridgell              1999-2005
   Copyright (C) Paul `Rusty' Russell		   2000
   Copyright (C) Jeremy Allison			   2000-2003

     ** NOTE! The following LGPL license applies to the tdb
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/


#include "tdb_private.h"

/* check for an out of bounds access - if it is out of bounds then
   see if the database has been expanded by someone else and expand
   if necessary
*/
static int tdb_oob(struct tdb_context *tdb, tdb_off_t off, tdb_len_t len,
		   int probe)
{
	struct stat st;
	if (len + off < len) {
		if (!probe) {
			/* Ensure ecode is set for log fn. */
			tdb->ecode = TDB_ERR_IO;
			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob off %u len %u wrap\n",
				 off, len));
		}
		return -1;
	}

	if (off + len <= tdb->map_size)
		return 0;
	if (tdb->flags & TDB_INTERNAL) {
		if (!probe) {
			/* Ensure ecode is set for log fn. */
			tdb->ecode = TDB_ERR_IO;
			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond internal malloc size %u\n",
				 (int)(off + len), (int)tdb->map_size));
		}
		return -1;
	}

	if (fstat(tdb->fd, &st) == -1) {
		tdb->ecode = TDB_ERR_IO;
		return -1;
	}

	/* Beware >4G files! */
	if ((tdb_off_t)st.st_size != st.st_size) {
		/* Ensure ecode is set for log fn. */
		tdb->ecode = TDB_ERR_IO;
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_oob len %llu too large!\n",
			 (long long)st.st_size));
		return -1;
	}

	/* Unmap, update size, remap.  We do this unconditionally, to handle
	 * the unusual case where the db is truncated.
	 *
	 * This can happen to a child using tdb_reopen_all(true) on a
	 * TDB_CLEAR_IF_FIRST tdb whose parent crashes: the next
	 * opener will truncate the database. */
	if (tdb_munmap(tdb) == -1) {
		tdb->ecode = TDB_ERR_IO;
		return -1;
	}
	tdb->map_size = st.st_size;
	if (tdb_mmap(tdb) != 0) {
		return -1;
	}

	if (st.st_size < (size_t)off + len) {
		if (!probe) {
			/* Ensure ecode is set for log fn. */
			tdb->ecode = TDB_ERR_IO;
			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond eof at %u\n",
				 (int)(off + len), (int)st.st_size));
		}
		return -1;
	}
	return 0;
}

/* write a lump of data at a specified offset */
static int tdb_write(struct tdb_context *tdb, tdb_off_t off,
		     const void *buf, tdb_len_t len)
{
	if (len == 0) {
		return 0;
	}

	if (tdb->read_only || tdb->traverse_read) {
		tdb->ecode = TDB_ERR_RDONLY;
		return -1;
	}

	if (tdb->methods->tdb_oob(tdb, off, len, 0) != 0)
		return -1;

	if (tdb->map_ptr) {
		memcpy(off + (char *)tdb->map_ptr, buf, len);
	} else {
#ifdef HAVE_INCOHERENT_MMAP
		tdb->ecode = TDB_ERR_IO;
		return -1;
#else
		ssize_t written = pwrite(tdb->fd, buf, len, off);
		if ((written != (ssize_t)len) && (written != -1)) {
			/* try once more */
			tdb->ecode = TDB_ERR_IO;
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: wrote only "
				 "%zi of %u bytes at %u, trying once more\n",
				 written, len, off));
			written = pwrite(tdb->fd, (const char *)buf+written,
					 len-written,
					 off+written);
		}
		if (written == -1) {
			/* Ensure ecode is set for log fn. */
			tdb->ecode = TDB_ERR_IO;
			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_write failed at %u "
				 "len=%u (%s)\n", off, len, strerror(errno)));
			return -1;
		} else if (written != (ssize_t)len) {
			tdb->ecode = TDB_ERR_IO;
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: failed to "
				 "write %u bytes at %u in two attempts\n",
				 len, off));
			return -1;
		}
#endif
	}
	return 0;
}

/* Endian conversion: we only ever deal with 4 byte quantities */
void *tdb_convert(void *buf, uint32_t size)
{
	uint32_t i, *p = (uint32_t *)buf;
	for (i = 0; i < size / 4; i++)
		p[i] = TDB_BYTEREV(p[i]);
	return buf;
}


/* read a lump of data at a specified offset, maybe convert */
static int tdb_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
		    tdb_len_t len, int cv)
{
	if (tdb->methods->tdb_oob(tdb, off, len, 0) != 0) {
		return -1;
	}

	if (tdb->map_ptr) {
		memcpy(buf, off + (char *)tdb->map_ptr, len);
	} else {
#ifdef HAVE_INCOHERENT_MMAP
		tdb->ecode = TDB_ERR_IO;
		return -1;
#else
		ssize_t ret = pread(tdb->fd, buf, len, off);
		if (ret != (ssize_t)len) {
			/* Ensure ecode is set for log fn. */
			tdb->ecode = TDB_ERR_IO;
			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_read failed at %u "
				 "len=%u ret=%zi (%s) map_size=%u\n",
				 off, len, ret, strerror(errno),
				 tdb->map_size));
			return -1;
		}
#endif
	}
	if (cv) {
		tdb_convert(buf, len);
	}
	return 0;
}



/*
  do an unlocked scan of the hash table heads to find the next non-zero head. The value
  will then be confirmed with the lock held
*/
static void tdb_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
{
	uint32_t h = *chain;
	if (tdb->map_ptr) {
		for (;h < tdb->hash_size;h++) {
			if (0 != *(uint32_t *)(TDB_HASH_TOP(h) + (unsigned char *)tdb->map_ptr)) {
				break;
			}
		}
	} else {
		uint32_t off=0;
		for (;h < tdb->hash_size;h++) {
			if (tdb_ofs_read(tdb, TDB_HASH_TOP(h), &off) != 0 || off != 0) {
				break;
			}
		}
	}
	(*chain) = h;
}


int tdb_munmap(struct tdb_context *tdb)
{
	if (tdb->flags & TDB_INTERNAL)
		return 0;

#ifdef HAVE_MMAP
	if (tdb->map_ptr) {
		int ret;

		ret = munmap(tdb->map_ptr, tdb->map_size);
		if (ret != 0)
			return ret;
	}
#endif
	tdb->map_ptr = NULL;
	return 0;
}

/* If mmap isn't coherent, *everyone* must always mmap. */
static bool should_mmap(const struct tdb_context *tdb)
{
#ifdef HAVE_INCOHERENT_MMAP
	return true;
#else
	return !(tdb->flags & TDB_NOMMAP);
#endif
}

int tdb_mmap(struct tdb_context *tdb)
{
	if (tdb->flags & TDB_INTERNAL)
		return 0;

#ifdef HAVE_MMAP
	if (should_mmap(tdb)) {
		tdb->map_ptr = mmap(NULL, tdb->map_size,
				    PROT_READ|(tdb->read_only? 0:PROT_WRITE),
				    MAP_SHARED|MAP_FILE, tdb->fd, 0);

		/*
		 * NB. When mmap fails it returns MAP_FAILED *NOT* NULL !!!!
		 */

		if (tdb->map_ptr == MAP_FAILED) {
			tdb->map_ptr = NULL;
			TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_mmap failed for size %u (%s)\n",
				 tdb->map_size, strerror(errno)));
#ifdef HAVE_INCOHERENT_MMAP
			tdb->ecode = TDB_ERR_IO;
			return -1;
#endif
		}
	} else {
		tdb->map_ptr = NULL;
	}
#else
	tdb->map_ptr = NULL;
#endif
	return 0;
}

/* expand a file.  we prefer to use ftruncate, as that is what posix
  says to use for mmap expansion */
static int tdb_expand_file(struct tdb_context *tdb, tdb_off_t size, tdb_off_t addition)
{
	char buf[8192];
	tdb_off_t new_size;

	if (tdb->read_only || tdb->traverse_read) {
		tdb->ecode = TDB_ERR_RDONLY;
		return -1;
	}

	if (!tdb_add_off_t(size, addition, &new_size)) {
		tdb->ecode = TDB_ERR_OOM;
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write "
			"overflow detected current size[%u] addition[%u]!\n",
			(unsigned)size, (unsigned)addition));
		errno = ENOSPC;
		return -1;
	}

	if (ftruncate(tdb->fd, new_size) == -1) {
		char b = 0;
		ssize_t written = pwrite(tdb->fd,  &b, 1, new_size - 1);
		if (written == 0) {
			/* try once more, potentially revealing errno */
			written = pwrite(tdb->fd,  &b, 1, new_size - 1);
		}
		if (written == 0) {
			/* again - give up, guessing errno */
			errno = ENOSPC;
		}
		if (written != 1) {
			tdb->ecode = TDB_ERR_OOM;
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file to %u failed (%s)\n",
				 (unsigned)new_size, strerror(errno)));
			return -1;
		}
	}

	/* now fill the file with something. This ensures that the
	   file isn't sparse, which would be very bad if we ran out of
	   disk. This must be done with write, not via mmap */
	memset(buf, TDB_PAD_BYTE, sizeof(buf));
	while (addition) {
		size_t n = addition>sizeof(buf)?sizeof(buf):addition;
		ssize_t written = pwrite(tdb->fd, buf, n, size);
		if (written == 0) {
			/* prevent infinite loops: try _once_ more */
			written = pwrite(tdb->fd, buf, n, size);
		}
		if (written == 0) {
			/* give up, trying to provide a useful errno */
			tdb->ecode = TDB_ERR_OOM;
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write "
				"returned 0 twice: giving up!\n"));
			errno = ENOSPC;
			return -1;
		}
		if (written == -1) {
			tdb->ecode = TDB_ERR_OOM;
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write of "
				 "%u bytes failed (%s)\n", (int)n,
				 strerror(errno)));
			return -1;
		}
		if (written != n) {
			TDB_LOG((tdb, TDB_DEBUG_WARNING, "expand_file: wrote "
				 "only %zu of %zi bytes - retrying\n", written,
				 n));
		}
		addition -= written;
		size += written;
	}
	return 0;
}


/* You need 'size', this tells you how much you should expand by. */
tdb_off_t tdb_expand_adjust(tdb_off_t map_size, tdb_off_t size, int page_size)
{
	tdb_off_t new_size, top_size, increment;
	tdb_off_t max_size = UINT32_MAX - map_size;

	if (size > max_size) {
		/*
		 * We can't round up anymore, just give back
		 * what we're asked for.
		 *
		 * The caller has to take care of the ENOSPC handling.
		 */
		return size;
	}

	/* limit size in order to avoid using up huge amounts of memory for
	 * in memory tdbs if an oddball huge record creeps in */
	if (size > 100 * 1024) {
		increment = size * 2;
	} else {
		increment = size * 100;
	}
	if (increment < size) {
		goto overflow;
	}

	if (!tdb_add_off_t(map_size, increment, &top_size)) {
		goto overflow;
	}

	/* always make room for at least top_size more records, and at
	   least 25% more space. if the DB is smaller than 100MiB,
	   otherwise grow it by 10% only. */
	if (map_size > 100 * 1024 * 1024) {
		new_size = map_size * 1.10;
	} else {
		new_size = map_size * 1.25;
	}
	if (new_size < map_size) {
		goto overflow;
	}

	/* Round the database up to a multiple of the page size */
	new_size = MAX(top_size, new_size);

	if (new_size + page_size < new_size) {
		/* There's a "+" in TDB_ALIGN that might overflow... */
		goto overflow;
	}

	return TDB_ALIGN(new_size, page_size) - map_size;

overflow:
	/*
	 * Somewhere in between we went over 4GB. Make one big jump to
	 * exactly 4GB database size.
	 */
	return max_size;
}

/* expand the database at least size bytes by expanding the underlying
   file and doing the mmap again if necessary */
int tdb_expand(struct tdb_context *tdb, tdb_off_t size)
{
	struct tdb_record rec;
	tdb_off_t offset;
	tdb_off_t new_size;

	if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
		TDB_LOG((tdb, TDB_DEBUG_ERROR, "lock failed in tdb_expand\n"));
		return -1;
	}

	/* must know about any previous expansions by another process */
	tdb->methods->tdb_oob(tdb, tdb->map_size, 1, 1);

	size = tdb_expand_adjust(tdb->map_size, size, tdb->page_size);

	if (!tdb_add_off_t(tdb->map_size, size, &new_size)) {
		tdb->ecode = TDB_ERR_OOM;
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_expand "
			"overflow detected current map_size[%u] size[%u]!\n",
			(unsigned)tdb->map_size, (unsigned)size));
		goto fail;
	}

	/* form a new freelist record */
	offset = tdb->map_size;
	memset(&rec,'\0',sizeof(rec));
	rec.rec_len = size - sizeof(rec);

	if (tdb->flags & TDB_INTERNAL) {
		char *new_map_ptr;

		new_map_ptr = (char *)realloc(tdb->map_ptr, new_size);
		if (!new_map_ptr) {
			tdb->ecode = TDB_ERR_OOM;
			goto fail;
		}
		tdb->map_ptr = new_map_ptr;
		tdb->map_size = new_size;
	} else {
		int ret;

		/*
		 * expand the file itself
		 */
		ret = tdb->methods->tdb_expand_file(tdb, tdb->map_size, size);
		if (ret != 0) {
			goto fail;
		}

		/* Explicitly remap: if we're in a transaction, this won't
		 * happen automatically! */
		tdb_munmap(tdb);
		tdb->map_size = new_size;
		if (tdb_mmap(tdb) != 0) {
			goto fail;
		}
	}

	/* link it into the free list */
	if (tdb_free(tdb, offset, &rec) == -1)
		goto fail;

	tdb_unlock(tdb, -1, F_WRLCK);
	return 0;
 fail:
	tdb_unlock(tdb, -1, F_WRLCK);
	return -1;
}

/* read/write a tdb_off_t */
int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d)
{
	return tdb->methods->tdb_read(tdb, offset, (char*)d, sizeof(*d), DOCONV());
}

int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d)
{
	tdb_off_t off = *d;
	return tdb->methods->tdb_write(tdb, offset, CONVERT(off), sizeof(*d));
}


/* read a lump of data, allocating the space for it */
unsigned char *tdb_alloc_read(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t len)
{
	unsigned char *buf;

	/* some systems don't like zero length malloc */

	if (!(buf = (unsigned char *)malloc(len ? len : 1))) {
		/* Ensure ecode is set for log fn. */
		tdb->ecode = TDB_ERR_OOM;
		TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_alloc_read malloc failed len=%u (%s)\n",
			   len, strerror(errno)));
		return NULL;
	}
	if (tdb->methods->tdb_read(tdb, offset, buf, len, 0) == -1) {
		SAFE_FREE(buf);
		return NULL;
	}
	return buf;
}

/* Give a piece of tdb data to a parser */

int tdb_parse_data(struct tdb_context *tdb, TDB_DATA key,
		   tdb_off_t offset, tdb_len_t len,
		   int (*parser)(TDB_DATA key, TDB_DATA data,
				 void *private_data),
		   void *private_data)
{
	TDB_DATA data;
	int result;

	data.dsize = len;

	if ((tdb->transaction == NULL) && (tdb->map_ptr != NULL)) {
		/*
		 * Optimize by avoiding the malloc/memcpy/free, point the
		 * parser directly at the mmap area.
		 */
		if (tdb->methods->tdb_oob(tdb, offset, len, 0) != 0) {
			return -1;
		}
		data.dptr = offset + (unsigned char *)tdb->map_ptr;
		return parser(key, data, private_data);
	}

	if (!(data.dptr = tdb_alloc_read(tdb, offset, len))) {
		return -1;
	}

	result = parser(key, data, private_data);
	free(data.dptr);
	return result;
}

/* read/write a record */
int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec)
{
	if (tdb->methods->tdb_read(tdb, offset, rec, sizeof(*rec),DOCONV()) == -1)
		return -1;
	if (TDB_BAD_MAGIC(rec)) {
		/* Ensure ecode is set for log fn. */
		tdb->ecode = TDB_ERR_CORRUPT;
		TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_rec_read bad magic 0x%x at offset=%u\n", rec->magic, offset));
		return -1;
	}
	return tdb->methods->tdb_oob(tdb, rec->next, sizeof(*rec), 0);
}

int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec)
{
	struct tdb_record r = *rec;
	return tdb->methods->tdb_write(tdb, offset, CONVERT(r), sizeof(r));
}

static const struct tdb_methods io_methods = {
	tdb_read,
	tdb_write,
	tdb_next_hash_chain,
	tdb_oob,
	tdb_expand_file,
};

/*
  initialise the default methods table
*/
void tdb_io_init(struct tdb_context *tdb)
{
	tdb->methods = &io_methods;
}