summaryrefslogtreecommitdiffstats
path: root/source4/lib/gencache.c
blob: f3740e3e12789b2a3e89b831c43b55936f765914 (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
/* 
   Unix SMB/CIFS implementation.

   Generic, persistent and shared between processes cache mechanism for use
   by various parts of the Samba code

   Copyright (C) Rafal Szczesniak    2002
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program 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 General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

#undef  DBGC_CLASS
#define DBGC_CLASS DBGC_TDB

#define TIMEOUT_LEN 12
#define CACHE_DATA_FMT	"%12u/%s"

static TDB_CONTEXT *cache;

/**
 * @file gencache.c
 * @brief Generic, persistent and shared between processes cache mechanism
 *        for use by various parts of the Samba code
 *
 **/


/**
 * Cache initialisation function. Opens cache tdb file or creates
 * it if does not exist.
 *
 * @return true on successful initialisation of the cache or
 *         false on failure
 **/

BOOL gencache_init(void)
{
	char* cache_fname = NULL;
	
	/* skip file open if it's already opened */
	if (cache) return True;

	asprintf(&cache_fname, "%s/%s", lp_lockdir(), "gencache.tdb");
	if (cache_fname)
		DEBUG(5, ("Opening cache file at %s\n", cache_fname));
	else {
		DEBUG(0, ("Filename allocation failed.\n"));
		return False;
	}

	cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT,
	                     O_RDWR|O_CREAT, 0644);

	SAFE_FREE(cache_fname);
	if (!cache) {
		DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
		return False;
	}
	return True;
}


/**
 * Cache shutdown function. Closes opened cache tdb file.
 *
 * @return true on successful closing the cache or
 *         false on failure during cache shutdown
 **/
 
BOOL gencache_shutdown(void)
{
	/* tdb_close routine returns -1 on error */
	if (!cache) return False;
	DEBUG(5, ("Closing cache file\n"));
	return tdb_close(cache) != -1;
}


/**
 * Set an entry in the cache file. If there's no such
 * one, then add it.
 *
 * @param keystr string that represents a key of this entry
 * @param value text representation value being cached
 * @param timeout time when the value is expired
 *
 * @retval true when entry is successfuly stored
 * @retval false on failure
 **/
 
BOOL gencache_set(const char *keystr, const char *value, time_t timeout)
{
	int ret;
	TDB_DATA keybuf, databuf;
	char* valstr = NULL;
	
	/* fail completely if get null pointers passed */
	SMB_ASSERT(keystr && value);

	if (!gencache_init()) return False;
	
	asprintf(&valstr, CACHE_DATA_FMT, (int)timeout, value);
	if (!valstr)
		return False;

	keybuf.dptr = strdup(keystr);
	keybuf.dsize = strlen(keystr)+1;
	databuf.dptr = strdup(valstr);
	databuf.dsize = strlen(valstr)+1;
	DEBUG(10, ("Adding cache entry with key = %s; value = %s and timeout \
	           = %s (%d seconds %s)\n", keybuf.dptr, value, ctime(&timeout),
	           (int)(timeout - time(NULL)), timeout > time(NULL) ? "ahead" : "in the past"));
		
	ret = tdb_store(cache, keybuf, databuf, 0);
	SAFE_FREE(valstr);
	SAFE_FREE(keybuf.dptr);
	SAFE_FREE(databuf.dptr);
	
	return ret == 0;
}


/**
 * Set existing entry to the cache file.
 *
 * @param keystr string that represents a key of this entry
 * @param valstr text representation value being cached
 * @param timeout time when the value is expired
 *
 * @retval true when entry is successfuly set
 * @retval false on failure
 **/

BOOL gencache_set_only(const char *keystr, const char *valstr, time_t timeout)
{
	int ret = -1;
	TDB_DATA keybuf, databuf;
	char *old_valstr, *datastr;
	time_t old_timeout;
	
	/* fail completely if get null pointers passed */
	SMB_ASSERT(keystr && valstr);

	if (!gencache_init()) return False;
			
	/* 
	 * Check whether entry exists in the cache
	 * Don't verify gencache_get exit code, since the entry may be expired
	 */	
	gencache_get(keystr, &old_valstr, &old_timeout);
	
	if (!(old_valstr && old_timeout)) return False;
		
	DEBUG(10, ("Setting cache entry with key = %s; old value = %s and old timeout \
	           = %s\n", keystr, old_valstr, ctime(&old_timeout)));

	asprintf(&datastr, CACHE_DATA_FMT, (int)timeout, valstr);
	keybuf.dptr = strdup(keystr);
	keybuf.dsize = strlen(keystr)+1;
	databuf.dptr = strdup(datastr);
	databuf.dsize = strlen(datastr)+1;
	DEBUGADD(10, ("New value = %s, new timeout = %s (%d seconds %s)", valstr,
	              ctime(&timeout), (int)(timeout - time(NULL)),
	              timeout > time(NULL) ? "ahead" : "in the past"));

		
	ret = tdb_store(cache, keybuf, databuf, TDB_REPLACE);

	SAFE_FREE(datastr);
	SAFE_FREE(old_valstr);
	SAFE_FREE(keybuf.dptr);
	SAFE_FREE(databuf.dptr);
	
	return ret == 0;
}
 

/**
 * Delete one entry from the cache file.
 *
 * @param keystr string that represents a key of this entry
 *
 * @retval true upon successful deletion
 * @retval false in case of failure
 **/

BOOL gencache_del(const char *keystr)
{
	int ret;
	TDB_DATA keybuf;
	
	/* fail completely if get null pointers passed */
	SMB_ASSERT(keystr);

	if (!gencache_init()) return False;	
	
	keybuf.dptr = strdup(keystr);
	keybuf.dsize = strlen(keystr)+1;
	DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
	ret = tdb_delete(cache, keybuf);
	
	SAFE_FREE(keybuf.dptr);
	return ret == 0;
}


/**
 * Get existing entry from the cache file.
 *
 * @param keystr string that represents a key of this entry
 * @param valstr buffer that is allocated and filled with the entry value
 *        buffer's disposing must be done outside
 * @param timeout pointer to a time_t that is filled with entry's
 *        timeout
 *
 * @retval true when entry is successfuly fetched
 * @retval False for failure
 **/

BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
{
	TDB_DATA keybuf, databuf;

	/* fail completely if get null pointers passed */
	SMB_ASSERT(keystr);

	if (!gencache_init())
		return False;
	
	keybuf.dptr = strdup(keystr);
	keybuf.dsize = strlen(keystr)+1;
	databuf = tdb_fetch(cache, keybuf);
	SAFE_FREE(keybuf.dptr);
	
	if (databuf.dptr && databuf.dsize > TIMEOUT_LEN) {
		char* entry_buf = strndup(databuf.dptr, databuf.dsize);
		char *v;
		time_t t;

		v = (char*)malloc(sizeof(char) * 
				  (databuf.dsize - TIMEOUT_LEN));
				
		SAFE_FREE(databuf.dptr);
		sscanf(entry_buf, CACHE_DATA_FMT, (int*)&t, v);
		SAFE_FREE(entry_buf);

		DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
			   "timeout = %s\n", t > time(NULL) ? "valid" :
			   "expired", keystr, v, ctime(&t)));

		if (valstr)
			*valstr = v;
		else
			SAFE_FREE(v);

		if (timeout)
			*timeout = t;

		return t > time(NULL);

	} else {
		SAFE_FREE(databuf.dptr);

		if (valstr)
			*valstr = NULL;

		if (timeout)
			timeout = NULL;

		DEBUG(10, ("Cache entry with key = %s couldn't be found\n", 
			   keystr));

		return False;
	}
}


/**
 * Iterate through all entries which key matches to specified pattern
 *
 * @param fn pointer to the function that will be supplied with each single
 *        matching cache entry (key, value and timeout) as an arguments
 * @param data void pointer to an arbitrary data that is passed directly to the fn
 *        function on each call
 * @param keystr_pattern pattern the existing entries' keys are matched to
 *
 **/

void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
                      void* data, const char* keystr_pattern)
{
	TDB_LIST_NODE *node, *first_node;
	TDB_DATA databuf;
	char *keystr = NULL, *valstr = NULL, *entry = NULL;
	time_t timeout = 0;

	/* fail completely if get null pointers passed */
	SMB_ASSERT(fn && keystr_pattern);

	if (!gencache_init()) return;

	DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
	node = tdb_search_keys(cache, keystr_pattern);
	first_node = node;
	
	while (node) {
		/* ensure null termination of the key string */
		keystr = strndup(node->node_key.dptr, node->node_key.dsize);
		
		/* 
		 * We don't use gencache_get function, because we need to iterate through
		 * all of the entries. Validity verification is up to fn routine.
		 */
		databuf = tdb_fetch(cache, node->node_key);
		if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
			SAFE_FREE(databuf.dptr);
			SAFE_FREE(keystr);
			node = node->next;
			continue;
		}
		entry = strndup(databuf.dptr, databuf.dsize);
		SAFE_FREE(databuf.dptr);
		valstr = (char*)malloc(sizeof(char) * (databuf.dsize - TIMEOUT_LEN));
		sscanf(entry, CACHE_DATA_FMT, (int*)(&timeout), valstr);
		
		DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
		           keystr, valstr, ctime(&timeout)));
		fn(keystr, valstr, timeout, data);
		
		SAFE_FREE(valstr);
		SAFE_FREE(entry);
		SAFE_FREE(keystr);
		node = node->next;
	}
	
	tdb_search_list_free(first_node);
}

/********************************************************************
 lock a key
********************************************************************/

int gencache_lock_entry( const char *key )
{
	return tdb_lock_bystring(cache, key, 0);
}

/********************************************************************
 unlock a key
********************************************************************/

void gencache_unlock_entry( const char *key )
{
	tdb_unlock_bystring(cache, key);
	return;
}