source: branches/samba-3.0/source/lib/gencache.c@ 621

Last change on this file since 621 was 1, checked in by Paul Smedley, 19 years ago

Initial code import
File size: 8.9 KB
Line 
1/*
2 Unix SMB/CIFS implementation.
3
4 Generic, persistent and shared between processes cache mechanism for use
5 by various parts of the Samba code
6
7 Copyright (C) Rafal Szczesniak 2002
8
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22*/
23
24#include "includes.h"
25
26#undef DBGC_CLASS
27#define DBGC_CLASS DBGC_TDB
28
29#define TIMEOUT_LEN 12
30#define CACHE_DATA_FMT "%12u/%s"
31#define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
32
33static TDB_CONTEXT *cache;
34static BOOL cache_readonly;
35
36/**
37 * @file gencache.c
38 * @brief Generic, persistent and shared between processes cache mechanism
39 * for use by various parts of the Samba code
40 *
41 **/
42
43
44/**
45 * Cache initialisation function. Opens cache tdb file or creates
46 * it if does not exist.
47 *
48 * @return true on successful initialisation of the cache or
49 * false on failure
50 **/
51
52BOOL gencache_init(void)
53{
54 char* cache_fname = NULL;
55
56 /* skip file open if it's already opened */
57 if (cache) return True;
58
59 cache_fname = lock_path("gencache.tdb");
60
61 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
62
63 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT,
64 O_RDWR|O_CREAT, 0644);
65
66 if (!cache && (errno == EACCES)) {
67 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT, O_RDONLY, 0644);
68 if (cache) {
69 cache_readonly = True;
70 DEBUG(5, ("gencache_init: Opening cache file %s read-only.\n", cache_fname));
71 }
72 }
73
74 if (!cache) {
75 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
76 return False;
77 }
78 return True;
79}
80
81
82/**
83 * Cache shutdown function. Closes opened cache tdb file.
84 *
85 * @return true on successful closing the cache or
86 * false on failure during cache shutdown
87 **/
88
89BOOL gencache_shutdown(void)
90{
91 int ret;
92 /* tdb_close routine returns -1 on error */
93 if (!cache) return False;
94 DEBUG(5, ("Closing cache file\n"));
95 ret = tdb_close(cache);
96 cache = NULL;
97 cache_readonly = False;
98 return ret != -1;
99}
100
101
102/**
103 * Set an entry in the cache file. If there's no such
104 * one, then add it.
105 *
106 * @param keystr string that represents a key of this entry
107 * @param value text representation value being cached
108 * @param timeout time when the value is expired
109 *
110 * @retval true when entry is successfuly stored
111 * @retval false on failure
112 **/
113
114BOOL gencache_set(const char *keystr, const char *value, time_t timeout)
115{
116 int ret;
117 TDB_DATA keybuf, databuf;
118 char* valstr = NULL;
119
120 /* fail completely if get null pointers passed */
121 SMB_ASSERT(keystr && value);
122
123 if (!gencache_init()) return False;
124
125 if (cache_readonly) {
126 return False;
127 }
128
129 asprintf(&valstr, CACHE_DATA_FMT, (int)timeout, value);
130 if (!valstr)
131 return False;
132
133 keybuf.dptr = CONST_DISCARD(char *, keystr);
134 keybuf.dsize = strlen(keystr)+1;
135 databuf.dptr = valstr;
136 databuf.dsize = strlen(valstr)+1;
137 DEBUG(10, ("Adding cache entry with key = %s; value = %s and timeout ="
138 " %s (%d seconds %s)\n", keybuf.dptr, value,ctime(&timeout),
139 (int)(timeout - time(NULL)),
140 timeout > time(NULL) ? "ahead" : "in the past"));
141
142 ret = tdb_store(cache, keybuf, databuf, 0);
143 SAFE_FREE(valstr);
144
145 return ret == 0;
146}
147
148/**
149 * Delete one entry from the cache file.
150 *
151 * @param keystr string that represents a key of this entry
152 *
153 * @retval true upon successful deletion
154 * @retval false in case of failure
155 **/
156
157BOOL gencache_del(const char *keystr)
158{
159 int ret;
160 TDB_DATA keybuf;
161
162 /* fail completely if get null pointers passed */
163 SMB_ASSERT(keystr);
164
165 if (!gencache_init()) return False;
166
167 if (cache_readonly) {
168 return False;
169 }
170
171 keybuf.dptr = CONST_DISCARD(char *, keystr);
172 keybuf.dsize = strlen(keystr)+1;
173 DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
174 ret = tdb_delete(cache, keybuf);
175
176 return ret == 0;
177}
178
179
180/**
181 * Get existing entry from the cache file.
182 *
183 * @param keystr string that represents a key of this entry
184 * @param valstr buffer that is allocated and filled with the entry value
185 * buffer's disposing must be done outside
186 * @param timeout pointer to a time_t that is filled with entry's
187 * timeout
188 *
189 * @retval true when entry is successfuly fetched
190 * @retval False for failure
191 **/
192
193BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
194{
195 TDB_DATA keybuf, databuf;
196 time_t t;
197 char *endptr;
198
199 /* fail completely if get null pointers passed */
200 SMB_ASSERT(keystr);
201
202 if (!gencache_init()) {
203 return False;
204 }
205
206 keybuf.dptr = CONST_DISCARD(char *, keystr);
207 keybuf.dsize = strlen(keystr)+1;
208 databuf = tdb_fetch(cache, keybuf);
209
210 if (databuf.dptr == NULL) {
211 DEBUG(10, ("Cache entry with key = %s couldn't be found\n",
212 keystr));
213 return False;
214 }
215
216 t = strtol(databuf.dptr, &endptr, 10);
217
218 if ((endptr == NULL) || (*endptr != '/')) {
219 DEBUG(2, ("Invalid gencache data format: %s\n", databuf.dptr));
220 SAFE_FREE(databuf.dptr);
221 return False;
222 }
223
224 DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
225 "timeout = %s", t > time(NULL) ? "valid" :
226 "expired", keystr, endptr+1, ctime(&t)));
227
228 if (t <= time(NULL)) {
229
230 /* We're expired, delete the entry */
231 tdb_delete(cache, keybuf);
232
233 SAFE_FREE(databuf.dptr);
234 return False;
235 }
236
237 if (valstr) {
238 *valstr = SMB_STRDUP(endptr+1);
239 if (*valstr == NULL) {
240 SAFE_FREE(databuf.dptr);
241 DEBUG(0, ("strdup failed\n"));
242 return False;
243 }
244 }
245
246 SAFE_FREE(databuf.dptr);
247
248 if (timeout) {
249 *timeout = t;
250 }
251
252 return True;
253}
254
255
256/**
257 * Iterate through all entries which key matches to specified pattern
258 *
259 * @param fn pointer to the function that will be supplied with each single
260 * matching cache entry (key, value and timeout) as an arguments
261 * @param data void pointer to an arbitrary data that is passed directly to the fn
262 * function on each call
263 * @param keystr_pattern pattern the existing entries' keys are matched to
264 *
265 **/
266
267void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
268 void* data, const char* keystr_pattern)
269{
270 TDB_LIST_NODE *node, *first_node;
271 TDB_DATA databuf;
272 char *keystr = NULL, *valstr = NULL, *entry = NULL;
273 time_t timeout = 0;
274 int status;
275 unsigned u;
276
277 /* fail completely if get null pointers passed */
278 SMB_ASSERT(fn && keystr_pattern);
279
280 if (!gencache_init()) return;
281
282 DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
283 node = tdb_search_keys(cache, keystr_pattern);
284 first_node = node;
285
286 while (node) {
287 char *fmt;
288
289 /* ensure null termination of the key string */
290 keystr = SMB_STRNDUP(node->node_key.dptr, node->node_key.dsize);
291 if (!keystr) {
292 break;
293 }
294
295 /*
296 * We don't use gencache_get function, because we need to iterate through
297 * all of the entries. Validity verification is up to fn routine.
298 */
299 databuf = tdb_fetch(cache, node->node_key);
300 if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
301 SAFE_FREE(databuf.dptr);
302 SAFE_FREE(keystr);
303 node = node->next;
304 continue;
305 }
306 entry = SMB_STRNDUP(databuf.dptr, databuf.dsize);
307 if (!entry) {
308 SAFE_FREE(databuf.dptr);
309 SAFE_FREE(keystr);
310 break;
311 }
312
313 SAFE_FREE(databuf.dptr);
314
315 valstr = (char *)SMB_MALLOC(databuf.dsize + 1 - TIMEOUT_LEN);
316 if (!valstr) {
317 SAFE_FREE(entry);
318 SAFE_FREE(keystr);
319 break;
320 }
321
322 asprintf(&fmt, READ_CACHE_DATA_FMT_TEMPLATE, (unsigned int)databuf.dsize - TIMEOUT_LEN);
323 if (!fmt) {
324 SAFE_FREE(valstr);
325 SAFE_FREE(entry);
326 SAFE_FREE(keystr);
327 break;
328 }
329 status = sscanf(entry, fmt, &u, valstr);
330 SAFE_FREE(fmt);
331
332 if ( status != 2 ) {
333 DEBUG(0,("gencache_iterate: invalid return from sscanf %d\n",status));
334 }
335 timeout = u;
336
337 DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
338 keystr, valstr, ctime(&timeout)));
339 fn(keystr, valstr, timeout, data);
340
341 SAFE_FREE(valstr);
342 SAFE_FREE(entry);
343 SAFE_FREE(keystr);
344 node = node->next;
345 }
346
347 tdb_search_list_free(first_node);
348}
349
350/********************************************************************
351 lock a key
352********************************************************************/
353
354int gencache_lock_entry( const char *key )
355{
356 if (!gencache_init())
357 return -1;
358
359 return tdb_lock_bystring(cache, key);
360}
361
362/********************************************************************
363 unlock a key
364********************************************************************/
365
366void gencache_unlock_entry( const char *key )
367{
368 if (!gencache_init())
369 return;
370
371 tdb_unlock_bystring(cache, key);
372 return;
373}
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