tdb2: unify tdb1_delete into tdb_delete.
[ccan] / ccan / tdb2 / tdb.c
1  /*
2    Trivial Database 2: fetch, store and misc routines.
3    Copyright (C) Rusty Russell 2010
4
5    This library is free software; you can redistribute it and/or
6    modify it under the terms of the GNU Lesser General Public
7    License as published by the Free Software Foundation; either
8    version 3 of the License, or (at your option) any later version.
9
10    This library is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13    Lesser General Public License for more details.
14
15    You should have received a copy of the GNU Lesser General Public
16    License along with this library; if not, see <http://www.gnu.org/licenses/>.
17 */
18 #include "private.h"
19 #include <ccan/asprintf/asprintf.h>
20 #include <stdarg.h>
21
22 static enum TDB_ERROR update_rec_hdr(struct tdb_context *tdb,
23                                      tdb_off_t off,
24                                      tdb_len_t keylen,
25                                      tdb_len_t datalen,
26                                      struct tdb_used_record *rec,
27                                      uint64_t h)
28 {
29         uint64_t dataroom = rec_data_length(rec) + rec_extra_padding(rec);
30         enum TDB_ERROR ecode;
31
32         ecode = set_header(tdb, rec, TDB_USED_MAGIC, keylen, datalen,
33                            keylen + dataroom, h);
34         if (ecode == TDB_SUCCESS) {
35                 ecode = tdb_write_convert(tdb, off, rec, sizeof(*rec));
36         }
37         return ecode;
38 }
39
40 static enum TDB_ERROR replace_data(struct tdb_context *tdb,
41                                    struct hash_info *h,
42                                    struct tdb_data key, struct tdb_data dbuf,
43                                    tdb_off_t old_off, tdb_len_t old_room,
44                                    bool growing)
45 {
46         tdb_off_t new_off;
47         enum TDB_ERROR ecode;
48
49         /* Allocate a new record. */
50         new_off = alloc(tdb, key.dsize, dbuf.dsize, h->h, TDB_USED_MAGIC,
51                         growing);
52         if (TDB_OFF_IS_ERR(new_off)) {
53                 return new_off;
54         }
55
56         /* We didn't like the existing one: remove it. */
57         if (old_off) {
58                 tdb->stats.frees++;
59                 ecode = add_free_record(tdb, old_off,
60                                         sizeof(struct tdb_used_record)
61                                         + key.dsize + old_room,
62                                         TDB_LOCK_WAIT, true);
63                 if (ecode == TDB_SUCCESS)
64                         ecode = replace_in_hash(tdb, h, new_off);
65         } else {
66                 ecode = add_to_hash(tdb, h, new_off);
67         }
68         if (ecode != TDB_SUCCESS) {
69                 return ecode;
70         }
71
72         new_off += sizeof(struct tdb_used_record);
73         ecode = tdb->tdb2.io->twrite(tdb, new_off, key.dptr, key.dsize);
74         if (ecode != TDB_SUCCESS) {
75                 return ecode;
76         }
77
78         new_off += key.dsize;
79         ecode = tdb->tdb2.io->twrite(tdb, new_off, dbuf.dptr, dbuf.dsize);
80         if (ecode != TDB_SUCCESS) {
81                 return ecode;
82         }
83
84         if (tdb->flags & TDB_SEQNUM)
85                 tdb_inc_seqnum(tdb);
86
87         return TDB_SUCCESS;
88 }
89
90 static enum TDB_ERROR update_data(struct tdb_context *tdb,
91                                   tdb_off_t off,
92                                   struct tdb_data dbuf,
93                                   tdb_len_t extra)
94 {
95         enum TDB_ERROR ecode;
96
97         ecode = tdb->tdb2.io->twrite(tdb, off, dbuf.dptr, dbuf.dsize);
98         if (ecode == TDB_SUCCESS && extra) {
99                 /* Put a zero in; future versions may append other data. */
100                 ecode = tdb->tdb2.io->twrite(tdb, off + dbuf.dsize, "", 1);
101         }
102         if (tdb->flags & TDB_SEQNUM)
103                 tdb_inc_seqnum(tdb);
104
105         return ecode;
106 }
107
108 enum TDB_ERROR tdb_store(struct tdb_context *tdb,
109                          struct tdb_data key, struct tdb_data dbuf, int flag)
110 {
111         struct hash_info h;
112         tdb_off_t off;
113         tdb_len_t old_room = 0;
114         struct tdb_used_record rec;
115         enum TDB_ERROR ecode;
116
117         if (tdb->flags & TDB_VERSION1) {
118                 if (tdb1_store(tdb, key, dbuf, flag) == -1)
119                         return tdb->last_error;
120                 return TDB_SUCCESS;
121         }
122
123         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
124         if (TDB_OFF_IS_ERR(off)) {
125                 return tdb->last_error = off;
126         }
127
128         /* Now we have lock on this hash bucket. */
129         if (flag == TDB_INSERT) {
130                 if (off) {
131                         ecode = TDB_ERR_EXISTS;
132                         goto out;
133                 }
134         } else {
135                 if (off) {
136                         old_room = rec_data_length(&rec)
137                                 + rec_extra_padding(&rec);
138                         if (old_room >= dbuf.dsize) {
139                                 /* Can modify in-place.  Easy! */
140                                 ecode = update_rec_hdr(tdb, off,
141                                                        key.dsize, dbuf.dsize,
142                                                        &rec, h.h);
143                                 if (ecode != TDB_SUCCESS) {
144                                         goto out;
145                                 }
146                                 ecode = update_data(tdb,
147                                                     off + sizeof(rec)
148                                                     + key.dsize, dbuf,
149                                                     old_room - dbuf.dsize);
150                                 if (ecode != TDB_SUCCESS) {
151                                         goto out;
152                                 }
153                                 tdb_unlock_hashes(tdb, h.hlock_start,
154                                                   h.hlock_range, F_WRLCK);
155                                 return tdb->last_error = TDB_SUCCESS;
156                         }
157                 } else {
158                         if (flag == TDB_MODIFY) {
159                                 /* if the record doesn't exist and we
160                                    are in TDB_MODIFY mode then we should fail
161                                    the store */
162                                 ecode = TDB_ERR_NOEXIST;
163                                 goto out;
164                         }
165                 }
166         }
167
168         /* If we didn't use the old record, this implies we're growing. */
169         ecode = replace_data(tdb, &h, key, dbuf, off, old_room, off);
170 out:
171         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
172         return tdb->last_error = ecode;
173 }
174
175 enum TDB_ERROR tdb_append(struct tdb_context *tdb,
176                           struct tdb_data key, struct tdb_data dbuf)
177 {
178         struct hash_info h;
179         tdb_off_t off;
180         struct tdb_used_record rec;
181         tdb_len_t old_room = 0, old_dlen;
182         unsigned char *newdata;
183         struct tdb_data new_dbuf;
184         enum TDB_ERROR ecode;
185
186         if (tdb->flags & TDB_VERSION1) {
187                 if (tdb1_append(tdb, key, dbuf) == -1)
188                         return tdb->last_error;
189                 return TDB_SUCCESS;
190         }
191
192         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
193         if (TDB_OFF_IS_ERR(off)) {
194                 return tdb->last_error = off;
195         }
196
197         if (off) {
198                 old_dlen = rec_data_length(&rec);
199                 old_room = old_dlen + rec_extra_padding(&rec);
200
201                 /* Fast path: can append in place. */
202                 if (rec_extra_padding(&rec) >= dbuf.dsize) {
203                         ecode = update_rec_hdr(tdb, off, key.dsize,
204                                                old_dlen + dbuf.dsize, &rec,
205                                                h.h);
206                         if (ecode != TDB_SUCCESS) {
207                                 goto out;
208                         }
209
210                         off += sizeof(rec) + key.dsize + old_dlen;
211                         ecode = update_data(tdb, off, dbuf,
212                                             rec_extra_padding(&rec));
213                         goto out;
214                 }
215
216                 /* Slow path. */
217                 newdata = malloc(key.dsize + old_dlen + dbuf.dsize);
218                 if (!newdata) {
219                         ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
220                                            "tdb_append:"
221                                            " failed to allocate %zu bytes",
222                                            (size_t)(key.dsize + old_dlen
223                                                     + dbuf.dsize));
224                         goto out;
225                 }
226                 ecode = tdb->tdb2.io->tread(tdb, off + sizeof(rec) + key.dsize,
227                                             newdata, old_dlen);
228                 if (ecode != TDB_SUCCESS) {
229                         goto out_free_newdata;
230                 }
231                 memcpy(newdata + old_dlen, dbuf.dptr, dbuf.dsize);
232                 new_dbuf.dptr = newdata;
233                 new_dbuf.dsize = old_dlen + dbuf.dsize;
234         } else {
235                 newdata = NULL;
236                 new_dbuf = dbuf;
237         }
238
239         /* If they're using tdb_append(), it implies they're growing record. */
240         ecode = replace_data(tdb, &h, key, new_dbuf, off, old_room, true);
241
242 out_free_newdata:
243         free(newdata);
244 out:
245         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
246         return tdb->last_error = ecode;
247 }
248
249 enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
250                          struct tdb_data *data)
251 {
252         tdb_off_t off;
253         struct tdb_used_record rec;
254         struct hash_info h;
255         enum TDB_ERROR ecode;
256
257         if (tdb->flags & TDB_VERSION1)
258                 return tdb1_fetch(tdb, key, data);
259
260         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
261         if (TDB_OFF_IS_ERR(off)) {
262                 return tdb->last_error = off;
263         }
264
265         if (!off) {
266                 ecode = TDB_ERR_NOEXIST;
267         } else {
268                 data->dsize = rec_data_length(&rec);
269                 data->dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
270                                             data->dsize);
271                 if (TDB_PTR_IS_ERR(data->dptr)) {
272                         ecode = TDB_PTR_ERR(data->dptr);
273                 } else
274                         ecode = TDB_SUCCESS;
275         }
276
277         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
278         return tdb->last_error = ecode;
279 }
280
281 bool tdb_exists(struct tdb_context *tdb, TDB_DATA key)
282 {
283         tdb_off_t off;
284         struct tdb_used_record rec;
285         struct hash_info h;
286
287         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
288         if (TDB_OFF_IS_ERR(off)) {
289                 tdb->last_error = off;
290                 return false;
291         }
292         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
293
294         tdb->last_error = TDB_SUCCESS;
295         return off ? true : false;
296 }
297
298 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key)
299 {
300         tdb_off_t off;
301         struct tdb_used_record rec;
302         struct hash_info h;
303         enum TDB_ERROR ecode;
304
305         if (tdb->flags & TDB_VERSION1) {
306                 if (tdb1_delete(tdb, key) == -1)
307                         return tdb->last_error;
308                 return TDB_SUCCESS;
309         }
310
311         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
312         if (TDB_OFF_IS_ERR(off)) {
313                 return tdb->last_error = off;
314         }
315
316         if (!off) {
317                 ecode = TDB_ERR_NOEXIST;
318                 goto unlock;
319         }
320
321         ecode = delete_from_hash(tdb, &h);
322         if (ecode != TDB_SUCCESS) {
323                 goto unlock;
324         }
325
326         /* Free the deleted entry. */
327         tdb->stats.frees++;
328         ecode = add_free_record(tdb, off,
329                                 sizeof(struct tdb_used_record)
330                                 + rec_key_length(&rec)
331                                 + rec_data_length(&rec)
332                                 + rec_extra_padding(&rec),
333                                 TDB_LOCK_WAIT, true);
334
335         if (tdb->flags & TDB_SEQNUM)
336                 tdb_inc_seqnum(tdb);
337
338 unlock:
339         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
340         return tdb->last_error = ecode;
341 }
342
343 unsigned int tdb_get_flags(struct tdb_context *tdb)
344 {
345         return tdb->flags;
346 }
347
348 static bool inside_transaction(const struct tdb_context *tdb)
349 {
350         if (tdb->flags & TDB_VERSION1)
351                 return tdb->tdb1.transaction != NULL;
352         else
353                 return tdb->tdb2.transaction != NULL;
354 }
355
356 static bool readonly_changable(struct tdb_context *tdb, const char *caller)
357 {
358         if (inside_transaction(tdb)) {
359                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
360                                              TDB_LOG_USE_ERROR,
361                                              "%s: can't change"
362                                              " TDB_RDONLY inside transaction",
363                                              caller);
364                 return false;
365         }
366
367         if (tdb->file->allrecord_lock.count != 0
368             || tdb->file->num_lockrecs != 0) {
369                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
370                                              TDB_LOG_USE_ERROR,
371                                              "%s: can't change"
372                                              " TDB_RDONLY holding locks",
373                                              caller);
374                 return false;
375         }
376         return true;
377 }
378
379 void tdb_add_flag(struct tdb_context *tdb, unsigned flag)
380 {
381         if (tdb->flags & TDB_INTERNAL) {
382                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
383                                              TDB_LOG_USE_ERROR,
384                                              "tdb_add_flag: internal db");
385                 return;
386         }
387         switch (flag) {
388         case TDB_NOLOCK:
389                 tdb->flags |= TDB_NOLOCK;
390                 break;
391         case TDB_NOMMAP:
392                 tdb->flags |= TDB_NOMMAP;
393                 tdb_munmap(tdb->file);
394                 break;
395         case TDB_NOSYNC:
396                 tdb->flags |= TDB_NOSYNC;
397                 break;
398         case TDB_SEQNUM:
399                 tdb->flags |= TDB_SEQNUM;
400                 break;
401         case TDB_ALLOW_NESTING:
402                 tdb->flags |= TDB_ALLOW_NESTING;
403                 break;
404         case TDB_RDONLY:
405                 if (readonly_changable(tdb, "tdb_add_flag"))
406                         tdb->flags |= TDB_RDONLY;
407                 break;
408         default:
409                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
410                                              TDB_LOG_USE_ERROR,
411                                              "tdb_add_flag: Unknown flag %u",
412                                              flag);
413         }
414 }
415
416 void tdb_remove_flag(struct tdb_context *tdb, unsigned flag)
417 {
418         if (tdb->flags & TDB_INTERNAL) {
419                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
420                                              TDB_LOG_USE_ERROR,
421                                              "tdb_remove_flag: internal db");
422                 return;
423         }
424         switch (flag) {
425         case TDB_NOLOCK:
426                 tdb->flags &= ~TDB_NOLOCK;
427                 break;
428         case TDB_NOMMAP:
429                 tdb->flags &= ~TDB_NOMMAP;
430                 tdb_mmap(tdb);
431                 break;
432         case TDB_NOSYNC:
433                 tdb->flags &= ~TDB_NOSYNC;
434                 break;
435         case TDB_SEQNUM:
436                 tdb->flags &= ~TDB_SEQNUM;
437                 break;
438         case TDB_ALLOW_NESTING:
439                 tdb->flags &= ~TDB_ALLOW_NESTING;
440                 break;
441         case TDB_RDONLY:
442                 if ((tdb->open_flags & O_ACCMODE) == O_RDONLY) {
443                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
444                                                      TDB_LOG_USE_ERROR,
445                                                      "tdb_remove_flag: can't"
446                                                      " remove TDB_RDONLY on tdb"
447                                                      " opened with O_RDONLY");
448                         break;
449                 }
450                 if (readonly_changable(tdb, "tdb_remove_flag"))
451                         tdb->flags &= ~TDB_RDONLY;
452                 break;
453         default:
454                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
455                                              TDB_LOG_USE_ERROR,
456                                              "tdb_remove_flag: Unknown flag %u",
457                                              flag);
458         }
459 }
460
461 const char *tdb_errorstr(enum TDB_ERROR ecode)
462 {
463         /* Gcc warns if you miss a case in the switch, so use that. */
464         switch (ecode) {
465         case TDB_SUCCESS: return "Success";
466         case TDB_ERR_CORRUPT: return "Corrupt database";
467         case TDB_ERR_IO: return "IO Error";
468         case TDB_ERR_LOCK: return "Locking error";
469         case TDB_ERR_OOM: return "Out of memory";
470         case TDB_ERR_EXISTS: return "Record exists";
471         case TDB_ERR_EINVAL: return "Invalid parameter";
472         case TDB_ERR_NOEXIST: return "Record does not exist";
473         case TDB_ERR_RDONLY: return "write not permitted";
474         }
475         return "Invalid error code";
476 }
477
478 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
479 {
480         return tdb->last_error;
481 }
482
483 enum TDB_ERROR COLD tdb_logerr(struct tdb_context *tdb,
484                                enum TDB_ERROR ecode,
485                                enum tdb_log_level level,
486                                const char *fmt, ...)
487 {
488         char *message;
489         va_list ap;
490         size_t len;
491         /* tdb_open paths care about errno, so save it. */
492         int saved_errno = errno;
493
494         if (!tdb->log_fn)
495                 return ecode;
496
497         va_start(ap, fmt);
498         len = vasprintf(&message, fmt, ap);
499         va_end(ap);
500
501         if (len < 0) {
502                 tdb->log_fn(tdb, TDB_LOG_ERROR, TDB_ERR_OOM,
503                             "out of memory formatting message:", tdb->log_data);
504                 tdb->log_fn(tdb, level, ecode, fmt, tdb->log_data);
505         } else {
506                 tdb->log_fn(tdb, level, ecode, message, tdb->log_data);
507                 free(message);
508         }
509         errno = saved_errno;
510         return ecode;
511 }
512
513 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
514                                  TDB_DATA key,
515                                  enum TDB_ERROR (*parse)(TDB_DATA k,
516                                                          TDB_DATA d,
517                                                          void *data),
518                                  void *data)
519 {
520         tdb_off_t off;
521         struct tdb_used_record rec;
522         struct hash_info h;
523         enum TDB_ERROR ecode;
524
525         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
526         if (TDB_OFF_IS_ERR(off)) {
527                 return tdb->last_error = off;
528         }
529
530         if (!off) {
531                 ecode = TDB_ERR_NOEXIST;
532         } else {
533                 const void *dptr;
534                 dptr = tdb_access_read(tdb, off + sizeof(rec) + key.dsize,
535                                        rec_data_length(&rec), false);
536                 if (TDB_PTR_IS_ERR(dptr)) {
537                         ecode = TDB_PTR_ERR(dptr);
538                 } else {
539                         TDB_DATA d = tdb_mkdata(dptr, rec_data_length(&rec));
540
541                         ecode = parse(key, d, data);
542                         tdb_access_release(tdb, dptr);
543                 }
544         }
545
546         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
547         return tdb->last_error = ecode;
548 }
549
550 const char *tdb_name(const struct tdb_context *tdb)
551 {
552         return tdb->name;
553 }
554
555 int64_t tdb_get_seqnum(struct tdb_context *tdb)
556 {
557         tdb_off_t off = tdb_read_off(tdb, offsetof(struct tdb_header, seqnum));
558         if (TDB_OFF_IS_ERR(off))
559                 tdb->last_error = off;
560         else
561                 tdb->last_error = TDB_SUCCESS;
562         return off;
563 }
564         
565
566 int tdb_fd(const struct tdb_context *tdb)
567 {
568         return tdb->file->fd;
569 }