Add a in-memory cache
[nivanova/samba-autobuild/.git] / source3 / smbd / statcache.c
1 /*
2    Unix SMB/CIFS implementation.
3    stat cache code
4    Copyright (C) Andrew Tridgell 1992-2000
5    Copyright (C) Jeremy Allison 1999-2007
6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2003
7    Copyright (C) Volker Lendecke 2007
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 3 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, see <http://www.gnu.org/licenses/>.
21 */
22
23 #include "includes.h"
24
25 /****************************************************************************
26  Stat cache code used in unix_convert.
27 *****************************************************************************/
28
29 /**
30  * Add an entry into the stat cache.
31  *
32  * @param full_orig_name       The original name as specified by the client
33  * @param orig_translated_path The name on our filesystem.
34  *
35  * @note Only the first strlen(orig_translated_path) characters are stored
36  *       into the cache.  This means that full_orig_name will be internally
37  *       truncated.
38  *
39  */
40
41 void stat_cache_add( const char *full_orig_name,
42                 char *translated_path,
43                 bool case_sensitive)
44 {
45         size_t translated_path_length;
46         char *original_path;
47         size_t original_path_length;
48         char saved_char;
49         TALLOC_CTX *ctx = talloc_tos();
50
51         if (!lp_stat_cache()) {
52                 return;
53         }
54
55         /*
56          * Don't cache trivial valid directory entries such as . and ..
57          */
58
59         if ((*full_orig_name == '\0')
60             || ISDOT(full_orig_name) || ISDOTDOT(full_orig_name)) {
61                 return;
62         }
63
64         /*
65          * If we are in case insentive mode, we don't need to
66          * store names that need no translation - else, it
67          * would be a waste.
68          */
69
70         if (case_sensitive && (strcmp(full_orig_name, translated_path) == 0)) {
71                 return;
72         }
73
74         /*
75          * Remove any trailing '/' characters from the
76          * translated path.
77          */
78
79         translated_path_length = strlen(translated_path);
80
81         if(translated_path[translated_path_length-1] == '/') {
82                 translated_path_length--;
83         }
84
85         if(case_sensitive) {
86                 original_path = talloc_strdup(ctx,full_orig_name);
87         } else {
88                 original_path = talloc_strdup_upper(ctx,full_orig_name);
89         }
90
91         if (!original_path) {
92                 return;
93         }
94
95         original_path_length = strlen(original_path);
96
97         if(original_path[original_path_length-1] == '/') {
98                 original_path[original_path_length-1] = '\0';
99                 original_path_length--;
100         }
101
102         if (original_path_length != translated_path_length) {
103                 if (original_path_length < translated_path_length) {
104                         DEBUG(0, ("OOPS - tried to store stat cache entry "
105                         "for weird length paths [%s] %lu and [%s] %lu)!\n",
106                                   original_path,
107                                   (unsigned long)original_path_length,
108                                   translated_path,
109                                   (unsigned long)translated_path_length));
110                         TALLOC_FREE(original_path);
111                         return;
112                 }
113
114                 /* we only want to index by the first part of original_path,
115                         up to the length of translated_path */
116
117                 original_path[translated_path_length] = '\0';
118                 original_path_length = translated_path_length;
119         }
120
121         /* Ensure we're null terminated. */
122         saved_char = translated_path[translated_path_length];
123         translated_path[translated_path_length] = '\0';
124
125         /*
126          * New entry or replace old entry.
127          */
128
129         memcache_add(
130                 smbd_memcache(), STAT_CACHE,
131                 data_blob_const(original_path, original_path_length),
132                 data_blob_const(translated_path, translated_path_length + 1));
133
134         DEBUG(5,("stat_cache_add: Added entry (%lx:size %x) %s -> %s\n",
135                  (unsigned long)translated_path,
136                  (unsigned int)translated_path_length,
137                  original_path,
138                  translated_path));
139
140         translated_path[translated_path_length] = saved_char;
141         TALLOC_FREE(original_path);
142 }
143
144 /**
145  * Look through the stat cache for an entry
146  *
147  * @param conn    A connection struct to do the stat() with.
148  * @param name    The path we are attempting to cache, modified by this routine
149  *                to be correct as far as the cache can tell us. We assume that
150  *                it is a talloc'ed string from top of stack, we free it if
151  *                necessary.
152  * @param dirpath The path as far as the stat cache told us. Also talloced
153  *                from top of stack.
154  * @param start   A pointer into name, for where to 'start' in fixing the rest
155  *                of the name up.
156  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
157  *
158  * @return True if we translated (and did a scuccessful stat on) the entire
159  *                name.
160  *
161  */
162
163 bool stat_cache_lookup(connection_struct *conn,
164                         char **pp_name,
165                         char **pp_dirpath,
166                         char **pp_start,
167                         SMB_STRUCT_STAT *pst)
168 {
169         char *chk_name;
170         size_t namelen;
171         bool sizechanged = False;
172         unsigned int num_components = 0;
173         char *translated_path;
174         size_t translated_path_length;
175         DATA_BLOB data_val;
176         char *name;
177         TALLOC_CTX *ctx = talloc_tos();
178
179         *pp_dirpath = NULL;
180         *pp_start = *pp_name;
181
182         if (!lp_stat_cache()) {
183                 return False;
184         }
185
186         name = *pp_name;
187         namelen = strlen(name);
188
189         DO_PROFILE_INC(statcache_lookups);
190
191         /*
192          * Don't lookup trivial valid directory entries.
193          */
194         if ((*name == '\0') || ISDOT(name) || ISDOTDOT(name)) {
195                 return False;
196         }
197
198         if (conn->case_sensitive) {
199                 chk_name = talloc_strdup(ctx,name);
200                 if (!chk_name) {
201                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
202                         return False;
203                 }
204
205         } else {
206                 chk_name = talloc_strdup_upper(ctx,name);
207                 if (!chk_name) {
208                         DEBUG(0, ("stat_cache_lookup: strdup_upper failed!\n"));
209                         return False;
210                 }
211
212                 /*
213                  * In some language encodings the length changes
214                  * if we uppercase. We need to treat this differently
215                  * below.
216                  */
217                 if (strlen(chk_name) != namelen) {
218                         sizechanged = True;
219                 }
220         }
221
222         while (1) {
223                 char *sp;
224
225                 data_val = data_blob_null;
226
227                 if (memcache_lookup(
228                             smbd_memcache(), STAT_CACHE,
229                             data_blob_const(chk_name, strlen(chk_name)),
230                             &data_val)) {
231                         break;
232                 }
233
234                 DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n",
235                                 chk_name ));
236                 /*
237                  * Didn't find it - remove last component for next try.
238                  */
239                 if (!(sp = strrchr_m(chk_name, '/'))) {
240                         /*
241                          * We reached the end of the name - no match.
242                          */
243                         DO_PROFILE_INC(statcache_misses);
244                         TALLOC_FREE(chk_name);
245                         return False;
246                 }
247
248                 *sp = '\0';
249
250                 /*
251                  * Count the number of times we have done this, we'll
252                  * need it when reconstructing the string.
253                  */
254
255                 if (sizechanged) {
256                         num_components++;
257                 }
258
259                 if ((*chk_name == '\0')
260                     || ISDOT(chk_name) || ISDOTDOT(chk_name)) {
261                         DO_PROFILE_INC(statcache_misses);
262                         TALLOC_FREE(chk_name);
263                         return False;
264                 }
265         }
266
267         translated_path = talloc_strdup(ctx,(char *)data_val.data);
268         if (!translated_path) {
269                 smb_panic("talloc failed");
270         }
271         translated_path_length = data_val.length - 1;
272
273         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] "
274                   "-> [%s]\n", chk_name, translated_path ));
275         DO_PROFILE_INC(statcache_hits);
276
277         if (SMB_VFS_STAT(conn, translated_path, pst) != 0) {
278                 /* Discard this entry - it doesn't exist in the filesystem. */
279                 memcache_delete(smbd_memcache(), STAT_CACHE,
280                                 data_blob_const(chk_name, strlen(chk_name)));
281                 TALLOC_FREE(chk_name);
282                 TALLOC_FREE(translated_path);
283                 return False;
284         }
285
286         if (!sizechanged) {
287                 memcpy(*pp_name, translated_path,
288                        MIN(namelen, translated_path_length));
289         } else {
290                 if (num_components == 0) {
291                         name = talloc_strndup(ctx, translated_path,
292                                            translated_path_length);
293                 } else {
294                         char *sp;
295
296                         sp = strnrchr_m(name, '/', num_components);
297                         if (sp) {
298                                 name = talloc_asprintf(ctx,"%.*s%s",
299                                          (int)translated_path_length,
300                                          translated_path, sp);
301                         } else {
302                                 name = talloc_strndup(ctx,
303                                                 translated_path,
304                                                 translated_path_length);
305                         }
306                 }
307                 if (name == NULL) {
308                         /*
309                          * TODO: Get us out of here with a real error message
310                          */
311                         smb_panic("talloc failed");
312                 }
313                 TALLOC_FREE(*pp_name);
314                 *pp_name = name;
315         }
316
317
318         /* set pointer for 'where to start' on fixing the rest of the name */
319         *pp_start = &name[translated_path_length];
320         if (**pp_start == '/') {
321                 ++*pp_start;
322         }
323
324         *pp_dirpath = translated_path;
325         TALLOC_FREE(chk_name);
326         return (namelen == translated_path_length);
327 }
328
329 /***************************************************************************
330  Tell all smbd's to delete an entry.
331 **************************************************************************/
332
333 void send_stat_cache_delete_message(const char *name)
334 {
335 #ifdef DEVELOPER
336         message_send_all(smbd_messaging_context(),
337                         MSG_SMB_STAT_CACHE_DELETE,
338                         name,
339                         strlen(name)+1,
340                         NULL);
341 #endif
342 }
343
344 /***************************************************************************
345  Delete an entry.
346 **************************************************************************/
347
348 void stat_cache_delete(const char *name)
349 {
350         char *lname = talloc_strdup_upper(talloc_tos(), name);
351
352         if (!lname) {
353                 return;
354         }
355         DEBUG(10,("stat_cache_delete: deleting name [%s] -> %s\n",
356                         lname, name ));
357
358         memcache_delete(smbd_memcache(), STAT_CACHE,
359                         data_blob_const(lname, talloc_get_size(lname)-1));
360         TALLOC_FREE(lname);
361 }
362
363 /***************************************************************
364  Compute a hash value based on a string key value.
365  The function returns the bucket index number for the hashed key.
366  JRA. Use a djb-algorithm hash for speed.
367 ***************************************************************/
368
369 unsigned int fast_string_hash(TDB_DATA *key)
370 {
371         unsigned int n = 0;
372         const char *p;
373         for (p = (const char *)key->dptr; *p != '\0'; p++) {
374                 n = ((n << 5) + n) ^ (unsigned int)(*p);
375         }
376         return n;
377 }
378
379 /***************************************************************************
380  Initializes or clears the stat cache.
381 **************************************************************************/
382
383 bool reset_stat_cache( void )
384 {
385         if (!lp_stat_cache())
386                 return True;
387
388         memcache_flush(smbd_memcache(), STAT_CACHE);
389
390         return True;
391 }