summaryrefslogtreecommitdiff
path: root/source4/lib/tdb/common/open.c
blob: e1f21aa8560b3e02bfadc2e0a61914de30f5f7da (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
 /* 
   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 2 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, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "tdb_private.h"

/* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
static struct tdb_context *tdbs = NULL;


/* This is based on the hash algorithm from gdbm */
static unsigned int default_tdb_hash(TDB_DATA *key)
{
	u32 value;	/* Used to compute the hash value.  */
	u32   i;	/* Used to cycle through random values. */

	/* Set the initial value from the key size. */
	for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++)
		value = (value + (key->dptr[i] << (i*5 % 24)));

	return (1103515243 * value + 12345);  
}


/* initialise a new database with a specified hash size */
static int tdb_new_database(struct tdb_context *tdb, int hash_size)
{
	struct tdb_header *newdb;
	int size, ret = -1;

	/* We make it up in memory, then write it out if not internal */
	size = sizeof(struct tdb_header) + (hash_size+1)*sizeof(tdb_off_t);
	if (!(newdb = (struct tdb_header *)calloc(size, 1)))
		return TDB_ERRCODE(TDB_ERR_OOM, -1);

	/* Fill in the header */
	newdb->version = TDB_VERSION;
	newdb->hash_size = hash_size;
	if (tdb->flags & TDB_INTERNAL) {
		tdb->map_size = size;
		tdb->map_ptr = (char *)newdb;
		memcpy(&tdb->header, newdb, sizeof(tdb->header));
		/* Convert the `ondisk' version if asked. */
		CONVERT(*newdb);
		return 0;
	}
	if (lseek(tdb->fd, 0, SEEK_SET) == -1)
		goto fail;

	if (ftruncate(tdb->fd, 0) == -1)
		goto fail;

	/* This creates an endian-converted header, as if read from disk */
	CONVERT(*newdb);
	memcpy(&tdb->header, newdb, sizeof(tdb->header));
	/* Don't endian-convert the magic food! */
	memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1);
	if (write(tdb->fd, newdb, size) != size) {
		ret = -1;
	} else {
		ret = 0;
	}

  fail:
	SAFE_FREE(newdb);
	return ret;
}



static int tdb_already_open(dev_t device,
			    ino_t ino)
{
	struct tdb_context *i;
	
	for (i = tdbs; i; i = i->next) {
		if (i->device == device && i->inode == ino) {
			return 1;
		}
	}

	return 0;
}

/* open the database, creating it if necessary 

   The open_flags and mode are passed straight to the open call on the
   database file. A flags value of O_WRONLY is invalid. The hash size
   is advisory, use zero for a default value.

   Return is NULL on error, in which case errno is also set.  Don't 
   try to call tdb_error or tdb_errname, just do strerror(errno).

   @param name may be NULL for internal databases. */
struct tdb_context *tdb_open(const char *name, int hash_size, int tdb_flags,
		      int open_flags, mode_t mode)
{
	return tdb_open_ex(name, hash_size, tdb_flags, open_flags, mode, NULL, NULL);
}

/* a default logging function */
static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...) PRINTF_ATTRIBUTE(3, 4);
static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...)
{
}


struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
				int open_flags, mode_t mode,
				const struct tdb_logging_context *log_ctx,
				tdb_hash_func hash_fn)
{
	struct tdb_context *tdb;
	struct stat st;
	int rev = 0, locked = 0;
	unsigned char *vp;
	u32 vertest;

	if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
		/* Can't log this */
		errno = ENOMEM;
		goto fail;
	}
	tdb_io_init(tdb);
	tdb->fd = -1;
	tdb->name = NULL;
	tdb->map_ptr = NULL;
	tdb->flags = tdb_flags;
	tdb->open_flags = open_flags;
	if (log_ctx) {
		tdb->log = *log_ctx;
	} else {
		tdb->log.log_fn = null_log_fn;
		tdb->log.log_private = NULL;
	}
	tdb->hash_fn = hash_fn ? hash_fn : default_tdb_hash;

	/* cache the page size */
	tdb->page_size = getpagesize();
	if (tdb->page_size <= 0) {
		tdb->page_size = 0x2000;
	}

	if ((open_flags & O_ACCMODE) == O_WRONLY) {
		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: can't open tdb %s write-only\n",
			 name));
		errno = EINVAL;
		goto fail;
	}
	
	if (hash_size == 0)
		hash_size = DEFAULT_HASH_SIZE;
	if ((open_flags & O_ACCMODE) == O_RDONLY) {
		tdb->read_only = 1;
		/* read only databases don't do locking or clear if first */
		tdb->flags |= TDB_NOLOCK;
		tdb->flags &= ~TDB_CLEAR_IF_FIRST;
	}

	/* internal databases don't mmap or lock, and start off cleared */
	if (tdb->flags & TDB_INTERNAL) {
		tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
		tdb->flags &= ~TDB_CLEAR_IF_FIRST;
		if (tdb_new_database(tdb, hash_size) != 0) {
			TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: tdb_new_database failed!"));
			goto fail;
		}
		goto internal;
	}

	if ((tdb->fd = open(name, open_flags, mode)) == -1) {
		TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_open_ex: could not open file %s: %s\n",
			 name, strerror(errno)));
		goto fail;	/* errno set by open(2) */
	}

	/* ensure there is only one process initialising at once */
	if (tdb->methods->tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to get global lock on %s: %s\n",
			 name, strerror(errno)));
		goto fail;	/* errno set by tdb_brlock */
	}

	/* we need to zero database if we are the only one with it open */
	if ((tdb_flags & TDB_CLEAR_IF_FIRST) &&
	    (locked = (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_WRLCK, F_SETLK, 0, 1) == 0))) {
		open_flags |= O_CREAT;
		if (ftruncate(tdb->fd, 0) == -1) {
			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
				 "failed to truncate %s: %s\n",
				 name, strerror(errno)));
			goto fail; /* errno set by ftruncate */
		}
	}

	if (read(tdb->fd, &tdb->header, sizeof(tdb->header)) != sizeof(tdb->header)
	    || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0
	    || (tdb->header.version != TDB_VERSION
		&& !(rev = (tdb->header.version==TDB_BYTEREV(TDB_VERSION))))) {
		/* its not a valid database - possibly initialise it */
		if (!(open_flags & O_CREAT) || tdb_new_database(tdb, hash_size) == -1) {
			errno = EIO; /* ie bad format or something */
			goto fail;
		}
		rev = (tdb->flags & TDB_CONVERT);
	}
	vp = (unsigned char *)&tdb->header.version;
	vertest = (((u32)vp[0]) << 24) | (((u32)vp[1]) << 16) |
		  (((u32)vp[2]) << 8) | (u32)vp[3];
	tdb->flags |= (vertest==TDB_VERSION) ? TDB_BIGENDIAN : 0;
	if (!rev)
		tdb->flags &= ~TDB_CONVERT;
	else {
		tdb->flags |= TDB_CONVERT;
		tdb_convert(&tdb->header, sizeof(tdb->header));
	}
	if (fstat(tdb->fd, &st) == -1)
		goto fail;

	if (tdb->header.rwlocks != 0) {
		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: spinlocks no longer supported\n"));
		goto fail;
	}

	/* Is it already in the open list?  If so, fail. */
	if (tdb_already_open(st.st_dev, st.st_ino)) {
		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
			 "%s (%d,%d) is already open in this process\n",
			 name, (int)st.st_dev, (int)st.st_ino));
		errno = EBUSY;
		goto fail;
	}

	if (!(tdb->name = (char *)strdup(name))) {
		errno = ENOMEM;
		goto fail;
	}

	tdb->map_size = st.st_size;
	tdb->device = st.st_dev;
	tdb->inode = st.st_ino;
	tdb->locked = (struct tdb_lock_type *)calloc(tdb->header.hash_size+1,
						     sizeof(tdb->locked[0]));
	if (!tdb->locked) {
		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
			 "failed to allocate lock structure for %s\n",
			 name));
		errno = ENOMEM;
		goto fail;
	}
	tdb_mmap(tdb);
	if (locked) {
		if (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_UNLCK, F_SETLK, 0, 1) == -1) {
			TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
				 "failed to take ACTIVE_LOCK on %s: %s\n",
				 name, strerror(errno)));
			goto fail;
		}

	}

	/* We always need to do this if the CLEAR_IF_FIRST flag is set, even if
	   we didn't get the initial exclusive lock as we need to let all other
	   users know we're using it. */

	if (tdb_flags & TDB_CLEAR_IF_FIRST) {
		/* leave this lock in place to indicate it's in use */
		if (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)
			goto fail;
	}

	/* if needed, run recovery */
	if (tdb_transaction_recover(tdb) == -1) {
		goto fail;
	}

 internal:
	/* Internal (memory-only) databases skip all the code above to
	 * do with disk files, and resume here by releasing their
	 * global lock and hooking into the active list. */
	if (tdb->methods->tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1) == -1)
		goto fail;
	tdb->next = tdbs;
	tdbs = tdb;
	return tdb;

 fail:
	{ int save_errno = errno;

	if (!tdb)
		return NULL;
	
	if (tdb->map_ptr) {
		if (tdb->flags & TDB_INTERNAL)
			SAFE_FREE(tdb->map_ptr);
		else
			tdb_munmap(tdb);
	}
	SAFE_FREE(tdb->name);
	if (tdb->fd != -1)
		if (close(tdb->fd) != 0)
			TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to close tdb->fd on error!\n"));
	SAFE_FREE(tdb->locked);
	SAFE_FREE(tdb);
	errno = save_errno;
	return NULL;
	}
}

/**
 * Close a database.
 *
 * @returns -1 for error; 0 for success.
 **/
int tdb_close(struct tdb_context *tdb)
{
	struct tdb_context **i;
	int ret = 0;

	if (tdb->transaction) {
		tdb_transaction_cancel(tdb);
	}

	if (tdb->map_ptr) {
		if (tdb->flags & TDB_INTERNAL)
			SAFE_FREE(tdb->map_ptr);
		else
			tdb_munmap(tdb);
	}
	SAFE_FREE(tdb->name);
	if (tdb->fd != -1)
		ret = close(tdb->fd);
	SAFE_FREE(tdb->locked);

	/* Remove from contexts list */
	for (i = &tdbs; *i; i = &(*i)->next) {
		if (*i == tdb) {
			*i = tdb->next;
			break;
		}
	}

	memset(tdb, 0, sizeof(*tdb));
	SAFE_FREE(tdb);

	return ret;
}

/* register a loging function */
void tdb_set_logging_function(struct tdb_context *tdb,
                              const struct tdb_logging_context *log)
{
        tdb->log = *log;
}

void *tdb_get_logging_private(struct tdb_context *tdb)
{
	return tdb->log.log_private;
}

/* reopen a tdb - this can be used after a fork to ensure that we have an independent
   seek pointer from our parent and to re-establish locks */
int tdb_reopen(struct tdb_context *tdb)
{
	struct stat st;

	if (tdb->flags & TDB_INTERNAL) {
		return 0; /* Nothing to do. */
	}

	if (tdb->num_locks != 0 || tdb->global_lock.count) {
		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed with locks held\n"));
		goto fail;
	}

	if (tdb->transaction != 0) {
		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed inside a transaction\n"));
		goto fail;
	}

	if (tdb_munmap(tdb) != 0) {
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: munmap failed (%s)\n", strerror(errno)));
		goto fail;
	}
	if (close(tdb->fd) != 0)
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: WARNING closing tdb->fd failed!\n"));
	tdb->fd = open(tdb->name, tdb->open_flags & ~(O_CREAT|O_TRUNC), 0);
	if (tdb->fd == -1) {
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: open failed (%s)\n", strerror(errno)));
		goto fail;
	}
	if ((tdb->flags & TDB_CLEAR_IF_FIRST) && 
	    (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)) {
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: failed to obtain active lock\n"));
		goto fail;
	}
	if (fstat(tdb->fd, &st) != 0) {
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: fstat failed (%s)\n", strerror(errno)));
		goto fail;
	}
	if (st.st_ino != tdb->inode || st.st_dev != tdb->device) {
		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: file dev/inode has changed!\n"));
		goto fail;
	}
	tdb_mmap(tdb);

	return 0;

fail:
	tdb_close(tdb);
	return -1;
}

/* reopen all tdb's */
int tdb_reopen_all(int parent_longlived)
{
	struct tdb_context *tdb;

	for (tdb=tdbs; tdb; tdb = tdb->next) {
		/*
		 * If the parent is longlived (ie. a
		 * parent daemon architecture), we know
		 * it will keep it's active lock on a
		 * tdb opened with CLEAR_IF_FIRST. Thus
		 * for child processes we don't have to
		 * add an active lock. This is essential
		 * to improve performance on systems that
		 * keep POSIX locks as a non-scalable data
		 * structure in the kernel.
		 */
		if (parent_longlived) {
			/* Ensure no clear-if-first. */
			tdb->flags &= ~TDB_CLEAR_IF_FIRST;
		}

		if (tdb_reopen(tdb) != 0)
			return -1;
	}

	return 0;
}