summaryrefslogtreecommitdiff
path: root/source4/lib/tdb/common/io.c
blob: 3b7e712cfe78b7d9a584f0b3c41e56bd278a3968 (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
 /* 
   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 
   note that "len" is the minimum length needed for the db
*/
static int tdb_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
{
	struct stat st;
	if (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 %d beyond internal malloc size %d\n",
				 (int)len, (int)tdb->map_size));
		}
		return TDB_ERRCODE(TDB_ERR_IO, -1);
	}

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

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

	/* Unmap, update size, remap */
	if (tdb_munmap(tdb) == -1)
		return TDB_ERRCODE(TDB_ERR_IO, -1);
	tdb->map_size = st.st_size;
	tdb_mmap(tdb);
	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 {
		ssize_t written = pwrite(tdb->fd, buf, len, off);
		if ((written != (ssize_t)len) && (written != -1)) {
			/* try once more */
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: wrote only "
				 "%d of %d bytes at %d, trying once more\n",
				 written, len, off));
			errno = ENOSPC;
			written = pwrite(tdb->fd, (void *)((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 %d "
				 "len=%d (%s)\n", off, len, strerror(errno)));
			return TDB_ERRCODE(TDB_ERR_IO, -1);
		} else if (written != (ssize_t)len) {
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: failed to "
				 "write %d bytes at %d in two attempts\n",
				 len, off));
			errno = ENOSPC;
			return TDB_ERRCODE(TDB_ERR_IO, -1);
		}
	}
	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 {
		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 %d "
				 "len=%d ret=%d (%s) map_size=%d\n",
				 (int)off, (int)len, (int)ret, strerror(errno),
				 (int)tdb->map_size));
			return TDB_ERRCODE(TDB_ERR_IO, -1);
		}
	}
	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->header.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->header.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 = munmap(tdb->map_ptr, tdb->map_size);
		if (ret != 0)
			return ret;
	}
#endif
	tdb->map_ptr = NULL;
	return 0;
}

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

#ifdef HAVE_MMAP
	if (!(tdb->flags & TDB_NOMMAP)) {
		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 %d (%s)\n", 
				 tdb->map_size, strerror(errno)));
		}
	} else {
		tdb->map_ptr = NULL;
	}
#else
	tdb->map_ptr = NULL;
#endif
}

/* 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[1024];

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

	if (ftruncate(tdb->fd, size+addition) == -1) {
		char b = 0;
		ssize_t written = pwrite(tdb->fd,  &b, 1, (size+addition) - 1);
		if (written == 0) {
			/* try once more, potentially revealing errno */
			written = pwrite(tdb->fd,  &b, 1, (size+addition) - 1);
		}
		if (written == 0) {
			/* again - give up, guessing errno */
			errno = ENOSPC;
		}
		if (written != 1) {
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file to %d failed (%s)\n", 
				 size+addition, 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_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write "
				"returned 0 twice: giving up!\n"));
			errno = ENOSPC;
			return -1;
		} else if (written == -1) {
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write of "
				"%d bytes failed (%s)\n", n, strerror(errno)));
			return -1;
		} else if (written != n) {
			TDB_LOG((tdb, TDB_DEBUG_WARNING, "expand_file: wrote "
				"only %d of %d bytes - retrying\n", written,n));
		}
		addition -= written;
		size += written;
	}
	return 0;
}


/* 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 list_struct rec;
	tdb_off_t offset;

	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);

	/* always make room for at least 10 more records, and round
           the database up to a multiple of the page size */
	size = TDB_ALIGN(tdb->map_size + size*10, tdb->page_size) - tdb->map_size;

	if (!(tdb->flags & TDB_INTERNAL))
		tdb_munmap(tdb);

	/*
	 * We must ensure the file is unmapped before doing this
	 * to ensure consistency with systems like OpenBSD where
	 * writes and mmaps are not consistent.
	 */

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

	tdb->map_size += size;

	if (tdb->flags & TDB_INTERNAL) {
		char *new_map_ptr = (char *)realloc(tdb->map_ptr,
						    tdb->map_size);
		if (!new_map_ptr) {
			tdb->map_size -= size;
			goto fail;
		}
		tdb->map_ptr = new_map_ptr;
	} else {
		/*
		 * We must ensure the file is remapped before adding the space
		 * to ensure consistency with systems like OpenBSD where
		 * writes and mmaps are not consistent.
		 */

		/* We're ok if the mmap fails as we'll fallback to read/write */
		tdb_mmap(tdb);
	}

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

	/* link it into the free list */
	offset = tdb->map_size - size;
	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 (len == 0) {
		len = 1;
	}

	if (!(buf = (unsigned char *)malloc(len))) {
		/* Ensure ecode is set for log fn. */
		tdb->ecode = TDB_ERR_OOM;
		TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_alloc_read malloc failed len=%d (%s)\n",
			   len, strerror(errno)));
		return TDB_ERRCODE(TDB_ERR_OOM, buf);
	}
	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 list_struct *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=%d\n", rec->magic, offset));
		return TDB_ERRCODE(TDB_ERR_CORRUPT, -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 list_struct *rec)
{
	struct list_struct 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,
	tdb_brlock
};

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