915b4c765afe51aa90e32030beb2b8b182390763
[ccan] / ccan / tdb2 / tdb.c
1 #include "private.h"
2 #include <ccan/tdb2/tdb2.h>
3 #include <ccan/hash/hash.h>
4 #include <ccan/build_assert/build_assert.h>
5 #include <ccan/likely/likely.h>
6 #include <assert.h>
7
8 /* The null return. */
9 struct tdb_data tdb_null = { .dptr = NULL, .dsize = 0 };
10
11 /* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
12 static struct tdb_context *tdbs = NULL;
13
14 PRINTF_ATTRIBUTE(4, 5) static void
15 null_log_fn(struct tdb_context *tdb,
16             enum tdb_debug_level level, void *priv,
17             const char *fmt, ...)
18 {
19 }
20
21 /* We do a lot of work assuming our copy of the header volatile area
22  * is uptodate, and usually it is.  However, once we grab a lock, we have to
23  * re-check it. */
24 bool header_changed(struct tdb_context *tdb)
25 {
26         uint64_t gen;
27
28         if (!(tdb->flags & TDB_NOLOCK) && tdb->header_uptodate) {
29                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
30                          "warning: header uptodate already\n");
31         }
32
33         /* We could get a partial update if we're not holding any locks. */
34         assert((tdb->flags & TDB_NOLOCK) || tdb_has_locks(tdb));
35
36         tdb->header_uptodate = true;
37         gen = tdb_read_off(tdb, offsetof(struct tdb_header, v.generation));
38         if (unlikely(gen != tdb->header.v.generation)) {
39                 tdb_read_convert(tdb, offsetof(struct tdb_header, v),
40                                  &tdb->header.v, sizeof(tdb->header.v));
41                 return true;
42         }
43         return false;
44 }
45
46 int write_header(struct tdb_context *tdb)
47 {
48         assert(tdb_read_off(tdb, offsetof(struct tdb_header, v.generation))
49                == tdb->header.v.generation);
50         tdb->header.v.generation++;
51         return tdb_write_convert(tdb, offsetof(struct tdb_header, v),
52                                  &tdb->header.v, sizeof(tdb->header.v));
53 }
54
55 static uint64_t jenkins_hash(const void *key, size_t length, uint64_t seed,
56                              void *arg)
57 {
58         return hash64_stable((const unsigned char *)key, length, seed);
59 }
60
61 uint64_t tdb_hash(struct tdb_context *tdb, const void *ptr, size_t len)
62 {
63         return tdb->khash(ptr, len, tdb->header.hash_seed, tdb->hash_priv);
64 }
65
66 static bool tdb_already_open(dev_t device, ino_t ino)
67 {
68         struct tdb_context *i;
69         
70         for (i = tdbs; i; i = i->next) {
71                 if (i->device == device && i->inode == ino) {
72                         return true;
73                 }
74         }
75
76         return false;
77 }
78
79 static uint64_t random_number(struct tdb_context *tdb)
80 {
81         int fd;
82         uint64_t ret = 0;
83         struct timeval now;
84
85         fd = open("/dev/urandom", O_RDONLY);
86         if (fd >= 0) {
87                 if (tdb_read_all(fd, &ret, sizeof(ret))) {
88                         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
89                                  "tdb_open: random from /dev/urandom\n");
90                         close(fd);
91                         return ret;
92                 }
93                 close(fd);
94         }
95         /* FIXME: Untested!  Based on Wikipedia protocol description! */
96         fd = open("/dev/egd-pool", O_RDWR);
97         if (fd >= 0) {
98                 /* Command is 1, next byte is size we want to read. */
99                 char cmd[2] = { 1, sizeof(uint64_t) };
100                 if (write(fd, cmd, sizeof(cmd)) == sizeof(cmd)) {
101                         char reply[1 + sizeof(uint64_t)];
102                         int r = read(fd, reply, sizeof(reply));
103                         if (r > 1) {
104                                 tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
105                                          "tdb_open: %u random bytes from"
106                                          " /dev/egd-pool\n", r-1);
107                                 /* Copy at least some bytes. */
108                                 memcpy(&ret, reply+1, r - 1);
109                                 if (reply[0] == sizeof(uint64_t)
110                                     && r == sizeof(reply)) {
111                                         close(fd);
112                                         return ret;
113                                 }
114                         }
115                 }
116                 close(fd);
117         }
118
119         /* Fallback: pid and time. */
120         gettimeofday(&now, NULL);
121         ret = getpid() * 100132289ULL + now.tv_sec * 1000000ULL + now.tv_usec;
122         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
123                  "tdb_open: random from getpid and time\n");
124         return ret;
125 }
126
127 struct new_database {
128         struct tdb_header hdr;
129         struct tdb_used_record hrec;
130         tdb_off_t hash[1ULL << INITIAL_HASH_BITS];
131         struct tdb_used_record frec;
132         tdb_off_t free[INITIAL_FREE_BUCKETS + 1]; /* One overflow bucket */
133 };
134
135 /* initialise a new database */
136 static int tdb_new_database(struct tdb_context *tdb)
137 {
138         /* We make it up in memory, then write it out if not internal */
139         struct new_database newdb;
140         unsigned int magic_off = offsetof(struct tdb_header, magic_food);
141
142         /* Fill in the header */
143         newdb.hdr.version = TDB_VERSION;
144         newdb.hdr.hash_seed = random_number(tdb);
145         newdb.hdr.hash_test = TDB_HASH_MAGIC;
146         newdb.hdr.hash_test = tdb->khash(&newdb.hdr.hash_test,
147                                          sizeof(newdb.hdr.hash_test),
148                                          newdb.hdr.hash_seed,
149                                          tdb->hash_priv);
150
151         newdb.hdr.v.generation = 0;
152
153         /* The initial zone must cover the initial database size! */
154         BUILD_ASSERT((1ULL << INITIAL_ZONE_BITS) >= sizeof(newdb));
155
156         /* Free array has 1 zone, 10 buckets.  All buckets empty. */
157         newdb.hdr.v.num_zones = 1;
158         newdb.hdr.v.zone_bits = INITIAL_ZONE_BITS;
159         newdb.hdr.v.free_buckets = INITIAL_FREE_BUCKETS;
160         newdb.hdr.v.free_off = offsetof(struct new_database, free);
161         set_header(tdb, &newdb.frec, 0,
162                    sizeof(newdb.free), sizeof(newdb.free), 0);
163         memset(newdb.free, 0, sizeof(newdb.free));
164
165         /* Initial hashes are empty. */
166         newdb.hdr.v.hash_bits = INITIAL_HASH_BITS;
167         newdb.hdr.v.hash_off = offsetof(struct new_database, hash);
168         set_header(tdb, &newdb.hrec, 0,
169                    sizeof(newdb.hash), sizeof(newdb.hash), 0);
170         memset(newdb.hash, 0, sizeof(newdb.hash));
171
172         /* Magic food */
173         memset(newdb.hdr.magic_food, 0, sizeof(newdb.hdr.magic_food));
174         strcpy(newdb.hdr.magic_food, TDB_MAGIC_FOOD);
175
176         /* This creates an endian-converted database, as if read from disk */
177         tdb_convert(tdb,
178                     (char *)&newdb.hdr + magic_off,
179                     sizeof(newdb) - magic_off);
180
181         tdb->header = newdb.hdr;
182
183         if (tdb->flags & TDB_INTERNAL) {
184                 tdb->map_size = sizeof(newdb);
185                 tdb->map_ptr = malloc(tdb->map_size);
186                 if (!tdb->map_ptr) {
187                         tdb->ecode = TDB_ERR_OOM;
188                         return -1;
189                 }
190                 memcpy(tdb->map_ptr, &newdb, tdb->map_size);
191                 return 0;
192         }
193         if (lseek(tdb->fd, 0, SEEK_SET) == -1)
194                 return -1;
195
196         if (ftruncate(tdb->fd, 0) == -1)
197                 return -1;
198
199         if (!tdb_pwrite_all(tdb->fd, &newdb, sizeof(newdb), 0)) {
200                 tdb->ecode = TDB_ERR_IO;
201                 return -1;
202         }
203         return 0;
204 }
205
206 struct tdb_context *tdb_open(const char *name, int tdb_flags,
207                              int open_flags, mode_t mode,
208                              union tdb_attribute *attr)
209 {
210         struct tdb_context *tdb;
211         struct stat st;
212         int save_errno;
213         uint64_t hash_test;
214         unsigned v;
215
216         tdb = malloc(sizeof(*tdb));
217         if (!tdb) {
218                 /* Can't log this */
219                 errno = ENOMEM;
220                 goto fail;
221         }
222         tdb->name = NULL;
223         tdb->map_ptr = NULL;
224         tdb->fd = -1;
225         /* map_size will be set below. */
226         tdb->ecode = TDB_SUCCESS;
227         /* header will be read in below. */
228         tdb->header_uptodate = false;
229         tdb->flags = tdb_flags;
230         tdb->log = null_log_fn;
231         tdb->log_priv = NULL;
232         tdb->khash = jenkins_hash;
233         tdb->hash_priv = NULL;
234         tdb->transaction = NULL;
235         /* last_zone will be set below. */
236         tdb_io_init(tdb);
237         tdb_lock_init(tdb);
238
239         while (attr) {
240                 switch (attr->base.attr) {
241                 case TDB_ATTRIBUTE_LOG:
242                         tdb->log = attr->log.log_fn;
243                         tdb->log_priv = attr->log.log_private;
244                         break;
245                 case TDB_ATTRIBUTE_HASH:
246                         tdb->khash = attr->hash.hash_fn;
247                         tdb->hash_priv = attr->hash.hash_private;
248                         break;
249                 default:
250                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
251                                  "tdb_open: unknown attribute type %u\n",
252                                  attr->base.attr);
253                         errno = EINVAL;
254                         goto fail;
255                 }
256                 attr = attr->base.next;
257         }
258
259         if ((open_flags & O_ACCMODE) == O_WRONLY) {
260                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
261                          "tdb_open: can't open tdb %s write-only\n", name);
262                 errno = EINVAL;
263                 goto fail;
264         }
265
266         if ((open_flags & O_ACCMODE) == O_RDONLY) {
267                 tdb->read_only = true;
268                 /* read only databases don't do locking */
269                 tdb->flags |= TDB_NOLOCK;
270         } else
271                 tdb->read_only = false;
272
273         /* internal databases don't need any of the rest. */
274         if (tdb->flags & TDB_INTERNAL) {
275                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
276                 if (tdb_new_database(tdb) != 0) {
277                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
278                                  "tdb_open: tdb_new_database failed!");
279                         goto fail;
280                 }
281                 TEST_IT(tdb->flags & TDB_CONVERT);
282                 tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
283                 /* Zones don't matter for internal db. */
284                 tdb->last_zone = 0;
285                 return tdb;
286         }
287
288         if ((tdb->fd = open(name, open_flags, mode)) == -1) {
289                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
290                          "tdb_open: could not open file %s: %s\n",
291                          name, strerror(errno));
292                 goto fail;      /* errno set by open(2) */
293         }
294
295         /* on exec, don't inherit the fd */
296         v = fcntl(tdb->fd, F_GETFD, 0);
297         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
298
299         /* ensure there is only one process initialising at once */
300         if (tdb_lock_open(tdb) == -1) {
301                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
302                          "tdb_open: failed to get open lock on %s: %s\n",
303                          name, strerror(errno));
304                 goto fail;      /* errno set by tdb_brlock */
305         }
306
307         if (!tdb_pread_all(tdb->fd, &tdb->header, sizeof(tdb->header), 0)
308             || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0) {
309                 if (!(open_flags & O_CREAT) || tdb_new_database(tdb) == -1) {
310                         if (errno == 0) {
311                                 errno = EIO; /* ie bad format or something */
312                         }
313                         goto fail;
314                 }
315         } else if (tdb->header.version != TDB_VERSION) {
316                 if (tdb->header.version == bswap_64(TDB_VERSION))
317                         tdb->flags |= TDB_CONVERT;
318                 else {
319                         /* wrong version */
320                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
321                                  "tdb_open: %s is unknown version 0x%llx\n",
322                                  name, (long long)tdb->header.version);
323                         errno = EIO;
324                         goto fail;
325                 }
326         }
327
328         tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
329         hash_test = TDB_HASH_MAGIC;
330         hash_test = tdb->khash(&hash_test, sizeof(hash_test),
331                                tdb->header.hash_seed, tdb->hash_priv);
332         if (tdb->header.hash_test != hash_test) {
333                 /* wrong hash variant */
334                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
335                          "tdb_open: %s uses a different hash function\n",
336                          name);
337                 errno = EIO;
338                 goto fail;
339         }
340
341         if (fstat(tdb->fd, &st) == -1)
342                 goto fail;
343
344         /* Is it already in the open list?  If so, fail. */
345         if (tdb_already_open(st.st_dev, st.st_ino)) {
346                 /* FIXME */
347                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
348                          "tdb_open: %s (%d,%d) is already open in this process\n",
349                          name, (int)st.st_dev, (int)st.st_ino);
350                 errno = EBUSY;
351                 goto fail;
352         }
353
354         tdb->name = strdup(name);
355         if (!tdb->name) {
356                 errno = ENOMEM;
357                 goto fail;
358         }
359
360         tdb->map_size = st.st_size;
361         tdb->device = st.st_dev;
362         tdb->inode = st.st_ino;
363         tdb_mmap(tdb);
364         tdb_unlock_open(tdb);
365         tdb_zone_init(tdb);
366
367         tdb->next = tdbs;
368         tdbs = tdb;
369         return tdb;
370
371  fail:
372         save_errno = errno;
373
374         if (!tdb)
375                 return NULL;
376
377 #ifdef TDB_TRACE
378         close(tdb->tracefd);
379 #endif
380         if (tdb->map_ptr) {
381                 if (tdb->flags & TDB_INTERNAL) {
382                         free(tdb->map_ptr);
383                 } else
384                         tdb_munmap(tdb);
385         }
386         free((char *)tdb->name);
387         if (tdb->fd != -1)
388                 if (close(tdb->fd) != 0)
389                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
390                                  "tdb_open: failed to close tdb->fd"
391                                  " on error!\n");
392         free(tdb);
393         errno = save_errno;
394         return NULL;
395 }
396
397 static tdb_off_t hash_off(struct tdb_context *tdb, uint64_t list)
398 {
399         return tdb->header.v.hash_off
400                 + ((list & ((1ULL << tdb->header.v.hash_bits) - 1))
401                    * sizeof(tdb_off_t));
402 }
403
404 /* Returns 0 if the entry is a zero (definitely not a match).
405  * Returns a valid entry offset if it's a match.  Fills in rec.
406  * Otherwise returns TDB_OFF_ERR: keep searching. */
407 static tdb_off_t entry_matches(struct tdb_context *tdb,
408                                uint64_t list,
409                                uint64_t hash,
410                                const struct tdb_data *key,
411                                struct tdb_used_record *rec)
412 {
413         tdb_off_t off;
414         uint64_t keylen;
415         const unsigned char *rkey;
416
417         list &= ((1ULL << tdb->header.v.hash_bits) - 1);
418
419         off = tdb_read_off(tdb, tdb->header.v.hash_off
420                            + list * sizeof(tdb_off_t));
421         if (off == 0 || off == TDB_OFF_ERR)
422                 return off;
423
424 #if 0 /* FIXME: Check other bits. */
425         unsigned int bits, bitmask, hoffextra;
426         /* Bottom three bits show how many extra hash bits. */
427         bits = (off & ((1 << TDB_EXTRA_HASHBITS_NUM) - 1)) + 1;
428         bitmask = (1 << bits)-1;
429         hoffextra = ((off >> TDB_EXTRA_HASHBITS_NUM) & bitmask);
430         uint64_t hextra = hash >> tdb->header.v.hash_bits;
431         if ((hextra & bitmask) != hoffextra) 
432                 return TDB_OFF_ERR;
433         off &= ~...;
434 #endif
435
436         if (tdb_read_convert(tdb, off, rec, sizeof(*rec)) == -1)
437                 return TDB_OFF_ERR;
438
439         /* FIXME: check extra bits in header! */
440         keylen = rec_key_length(rec);
441         if (keylen != key->dsize)
442                 return TDB_OFF_ERR;
443
444         rkey = tdb_access_read(tdb, off + sizeof(*rec), keylen, false);
445         if (!rkey)
446                 return TDB_OFF_ERR;
447         if (memcmp(rkey, key->dptr, keylen) != 0)
448                 off = TDB_OFF_ERR;
449         tdb_access_release(tdb, rkey);
450         return off;
451 }
452
453 /* FIXME: Optimize? */
454 static void unlock_lists(struct tdb_context *tdb,
455                          tdb_off_t list, tdb_len_t num,
456                          int ltype)
457 {
458         tdb_off_t i;
459
460         for (i = list; i < list + num; i++)
461                 tdb_unlock_list(tdb, i, ltype);
462 }
463
464 /* FIXME: Optimize? */
465 static int lock_lists(struct tdb_context *tdb,
466                       tdb_off_t list, tdb_len_t num,
467                       int ltype)
468 {
469         tdb_off_t i;
470
471         for (i = list; i < list + num; i++) {
472                 if (tdb_lock_list(tdb, i, ltype, TDB_LOCK_WAIT)
473                     == TDB_OFF_ERR) {
474                         unlock_lists(tdb, list, i - list, ltype);
475                         return -1;
476                 }
477         }
478         return 0;
479 }
480
481 /* We lock hashes up to the next empty offset.  We already hold the
482  * lock on the start bucket, but we may need to release and re-grab
483  * it.  If we fail, we hold no locks at all! */
484 static tdb_len_t relock_hash_to_zero(struct tdb_context *tdb,
485                                      tdb_off_t start, int ltype)
486 {
487         tdb_len_t num, len;
488
489 again:
490         num = 1ULL << tdb->header.v.hash_bits;
491         len = tdb_find_zero_off(tdb, hash_off(tdb, start), num - start);
492         if (unlikely(len == num - start)) {
493                 /* We hit the end of the hash range.  Drop lock: we have
494                    to lock start of hash first. */
495                 tdb_len_t pre_locks;
496
497                 tdb_unlock_list(tdb, start, ltype);
498
499                 /* Grab something, so header is stable. */
500                 if (tdb_lock_list(tdb, 0, ltype, TDB_LOCK_WAIT))
501                         return TDB_OFF_ERR;
502                 pre_locks = tdb_find_zero_off(tdb, hash_off(tdb, 0), num);
503                 /* We want to lock the zero entry as well. */
504                 pre_locks++;
505                 if (lock_lists(tdb, 1, pre_locks - 1, ltype) == -1) {
506                         tdb_unlock_list(tdb, 0, ltype);
507                         return TDB_OFF_ERR;
508                 }
509
510                 /* Now lock later ones. */
511                 if (unlikely(lock_lists(tdb, start, len, ltype) == -1)) {
512                         unlock_lists(tdb, 0, pre_locks, ltype);
513                         return TDB_OFF_ERR;
514                 }
515                 len += pre_locks;
516         } else {
517                 /* We want to lock the zero entry as well. */
518                 len++;
519                 /* But we already have lock on start. */
520                 if (unlikely(lock_lists(tdb, start+1, len-1, ltype) == -1)) {
521                         tdb_unlock_list(tdb, start, ltype);
522                         return TDB_OFF_ERR;
523                 }
524         }
525
526         /* Now, did we lose the race, and it's not zero any more? */
527         if (unlikely(tdb_read_off(tdb, hash_off(tdb, start + len - 1)) != 0)) {
528                 /* Leave the start locked, as expected. */
529                 unlock_lists(tdb, start + 1, len - 1, ltype);
530                 goto again;
531         }
532
533         return len;
534 }
535
536 /* FIXME: modify, don't rewrite! */
537 static int update_rec_hdr(struct tdb_context *tdb,
538                           tdb_off_t off,
539                           tdb_len_t keylen,
540                           tdb_len_t datalen,
541                           struct tdb_used_record *rec,
542                           uint64_t h)
543 {
544         uint64_t dataroom = rec_data_length(rec) + rec_extra_padding(rec);
545
546         if (set_header(tdb, rec, keylen, datalen, keylen + dataroom, h))
547                 return -1;
548
549         return tdb_write_convert(tdb, off, rec, sizeof(*rec));
550 }
551
552 /* If we fail, others will try after us. */
553 static void enlarge_hash(struct tdb_context *tdb)
554 {
555         tdb_off_t newoff, oldoff, i;
556         tdb_len_t hlen;
557         uint64_t h, num = 1ULL << tdb->header.v.hash_bits;
558         struct tdb_used_record pad, *r;
559
560         /* FIXME: We should do this without holding locks throughout. */
561         if (tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false) == -1)
562                 return;
563
564         /* Someone else enlarged for us?  Nothing to do. */
565         if ((1ULL << tdb->header.v.hash_bits) != num)
566                 goto unlock;
567
568         /* Allocate our new array. */
569         hlen = num * sizeof(tdb_off_t) * 2;
570         newoff = alloc(tdb, 0, hlen, 0, false);
571         if (unlikely(newoff == TDB_OFF_ERR))
572                 goto unlock;
573         if (unlikely(newoff == 0)) {
574                 if (tdb_expand(tdb, 0, hlen, false) == -1)
575                         goto unlock;
576                 newoff = alloc(tdb, 0, hlen, 0, false);
577                 if (newoff == TDB_OFF_ERR || newoff == 0)
578                         goto unlock;
579         }
580         /* Step over record header! */
581         newoff += sizeof(struct tdb_used_record);
582
583         /* Starts all zero. */
584         if (zero_out(tdb, newoff, hlen) == -1)
585                 goto unlock;
586
587         /* FIXME: If the space before is empty, we know this is in its ideal
588          * location.  Or steal a bit from the pointer to avoid rehash. */
589         for (i = tdb_find_nonzero_off(tdb, hash_off(tdb, 0), num);
590              i < num;
591              i += tdb_find_nonzero_off(tdb, hash_off(tdb, i), num - i)) {
592                 tdb_off_t off;
593                 off = tdb_read_off(tdb, hash_off(tdb, i));
594                 if (unlikely(off == TDB_OFF_ERR))
595                         goto unlock;
596                 if (unlikely(!off)) {
597                         tdb->ecode = TDB_ERR_CORRUPT;
598                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
599                                  "find_bucket_and_lock: zero hash bucket!\n");
600                         goto unlock;
601                 }
602                 h = hash_record(tdb, off);
603                 /* FIXME: Encode extra hash bits! */
604                 if (tdb_write_off(tdb, newoff
605                                   + (h & ((num * 2) - 1)) * sizeof(uint64_t),
606                                   off) == -1)
607                         goto unlock;
608         }
609
610         /* Free up old hash. */
611         oldoff = tdb->header.v.hash_off - sizeof(*r);
612         r = tdb_get(tdb, oldoff, &pad, sizeof(*r));
613         if (!r)
614                 goto unlock;
615         add_free_record(tdb, oldoff,
616                         sizeof(*r)+rec_data_length(r)+rec_extra_padding(r));
617
618         /* Now we write the modified header. */
619         tdb->header.v.hash_bits++;
620         tdb->header.v.hash_off = newoff;
621         write_header(tdb);
622 unlock:
623         tdb_allrecord_unlock(tdb, F_WRLCK);
624 }
625
626 int tdb_store(struct tdb_context *tdb,
627               struct tdb_data key, struct tdb_data dbuf, int flag)
628 {
629         tdb_off_t new_off, off, old_bucket, start, num_locks = 1;
630         struct tdb_used_record rec;
631         uint64_t h;
632         bool growing = false;
633
634         h = tdb_hash(tdb, key.dptr, key.dsize);
635
636         /* FIXME: can we avoid locks for some fast paths? */
637         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
638         if (start == TDB_OFF_ERR)
639                 return -1;
640
641         /* Fast path. */
642         old_bucket = start;
643         off = entry_matches(tdb, start, h, &key, &rec);
644         if (unlikely(off == TDB_OFF_ERR)) {
645                 /* Slow path, need to grab more locks and search. */
646                 tdb_off_t i;
647
648                 /* Warning: this may drop the lock!  Does that on error. */
649                 num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
650                 if (num_locks == TDB_OFF_ERR)
651                         return -1;
652
653                 for (i = start; i < start + num_locks; i++) {
654                         off = entry_matches(tdb, i, h, &key, &rec);
655                         /* Empty entry or we found it? */
656                         if (off == 0 || off != TDB_OFF_ERR)
657                                 break;
658                 }
659                 if (i == start + num_locks)
660                         off = 0;
661
662                 /* Even if not found, this is where we put the new entry. */
663                 old_bucket = i;
664         }
665
666         /* Now we have lock on this hash bucket. */
667         if (flag == TDB_INSERT) {
668                 if (off) {
669                         tdb->ecode = TDB_ERR_EXISTS;
670                         goto fail;
671                 }
672         } else {
673                 if (off) {
674                         if (rec_data_length(&rec) + rec_extra_padding(&rec)
675                             >= dbuf.dsize) {
676                                 new_off = off;
677                                 if (update_rec_hdr(tdb, off,
678                                                    key.dsize, dbuf.dsize,
679                                                    &rec, h))
680                                         goto fail;
681                                 goto write;
682                         }
683                         /* FIXME: See if right record is free? */
684                         /* Hint to allocator that we've realloced. */
685                         growing = true;
686                 } else {
687                         if (flag == TDB_MODIFY) {
688                                 /* if the record doesn't exist and we
689                                    are in TDB_MODIFY mode then we should fail
690                                    the store */
691                                 tdb->ecode = TDB_ERR_NOEXIST;
692                                 goto fail;
693                         }
694                 }
695         }
696
697         /* Allocate a new record. */
698         new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
699         if (new_off == 0) {
700                 unlock_lists(tdb, start, num_locks, F_WRLCK);
701                 /* Expand, then try again... */
702                 if (tdb_expand(tdb, key.dsize, dbuf.dsize, growing) == -1)
703                         return -1;
704                 return tdb_store(tdb, key, dbuf, flag);
705         }
706
707         /* We didn't like the existing one: remove it. */
708         if (off) {
709                 add_free_record(tdb, off, sizeof(struct tdb_used_record)
710                                 + rec_key_length(&rec)
711                                 + rec_data_length(&rec)
712                                 + rec_extra_padding(&rec));
713         }
714
715         /* FIXME: Encode extra hash bits! */
716         if (tdb_write_off(tdb, hash_off(tdb, old_bucket), new_off) == -1)
717                 goto fail;
718
719 write:
720         off = new_off + sizeof(struct tdb_used_record);
721         if (tdb->methods->write(tdb, off, key.dptr, key.dsize) == -1)
722                 goto fail;
723         off += key.dsize;
724         if (tdb->methods->write(tdb, off, dbuf.dptr, dbuf.dsize) == -1)
725                 goto fail;
726
727         /* FIXME: tdb_increment_seqnum(tdb); */
728         unlock_lists(tdb, start, num_locks, F_WRLCK);
729
730         /* FIXME: by simple simulation, this approximated 60% full.
731          * Check in real case! */
732         if (unlikely(num_locks > 4 * tdb->header.v.hash_bits - 30))
733                 enlarge_hash(tdb);
734
735         return 0;
736
737 fail:
738         unlock_lists(tdb, start, num_locks, F_WRLCK);
739         return -1;
740 }
741
742 struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
743 {
744         tdb_off_t off, start, num_locks = 1;
745         struct tdb_used_record rec;
746         uint64_t h;
747         struct tdb_data ret;
748
749         h = tdb_hash(tdb, key.dptr, key.dsize);
750
751         /* FIXME: can we avoid locks for some fast paths? */
752         start = tdb_lock_list(tdb, h, F_RDLCK, TDB_LOCK_WAIT);
753         if (start == TDB_OFF_ERR)
754                 return tdb_null;
755
756         /* Fast path. */
757         off = entry_matches(tdb, start, h, &key, &rec);
758         if (unlikely(off == TDB_OFF_ERR)) {
759                 /* Slow path, need to grab more locks and search. */
760                 tdb_off_t i;
761
762                 /* Warning: this may drop the lock!  Does that on error. */
763                 num_locks = relock_hash_to_zero(tdb, start, F_RDLCK);
764                 if (num_locks == TDB_OFF_ERR)
765                         return tdb_null;
766
767                 for (i = start; i < start + num_locks; i++) {
768                         off = entry_matches(tdb, i, h, &key, &rec);
769                         /* Empty entry or we found it? */
770                         if (off == 0 || off != TDB_OFF_ERR)
771                                 break;
772                 }
773                 if (i == start + num_locks)
774                         off = 0;
775         }
776
777         if (!off) {
778                 unlock_lists(tdb, start, num_locks, F_RDLCK);
779                 tdb->ecode = TDB_ERR_NOEXIST;
780                 return tdb_null;
781         }
782
783         ret.dsize = rec_data_length(&rec);
784         ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
785                                   ret.dsize);
786         unlock_lists(tdb, start, num_locks, F_RDLCK);
787         return ret;
788 }
789
790 static int hash_add(struct tdb_context *tdb, uint64_t h, tdb_off_t off)
791 {
792         tdb_off_t i, hoff, len, num;
793
794         /* Look for next space. */
795         i = (h & ((1ULL << tdb->header.v.hash_bits) - 1));
796         len = (1ULL << tdb->header.v.hash_bits) - i;
797         num = tdb_find_zero_off(tdb, hash_off(tdb, i), len);
798
799         if (unlikely(num == len)) {
800                 /* We wrapped.  Look through start of hash table. */
801                 hoff = hash_off(tdb, 0);
802                 len = (1ULL << tdb->header.v.hash_bits);
803                 num = tdb_find_zero_off(tdb, hoff, len);
804                 if (i == len) {
805                         tdb->ecode = TDB_ERR_CORRUPT;
806                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
807                                  "hash_add: full hash table!\n");
808                         return -1;
809                 }
810         }
811         /* FIXME: Encode extra hash bits! */
812         return tdb_write_off(tdb, hash_off(tdb, i + num), off);
813 }
814
815 int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
816 {
817         tdb_off_t i, old_bucket, off, start, num_locks = 1;
818         struct tdb_used_record rec;
819         uint64_t h;
820
821         h = tdb_hash(tdb, key.dptr, key.dsize);
822
823         /* FIXME: can we avoid locks for some fast paths? */
824         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
825         if (start == TDB_OFF_ERR)
826                 return -1;
827
828         /* Fast path. */
829         old_bucket = start;
830         off = entry_matches(tdb, start, h, &key, &rec);
831         if (off && off != TDB_OFF_ERR) {
832                 /* We can only really fastpath delete if next bucket
833                  * is 0.  Note that we haven't locked it, but our lock
834                  * on this bucket stops anyone overflowing into it
835                  * while we look. */
836                 if (tdb_read_off(tdb, hash_off(tdb, h+1)) == 0)
837                         goto delete;
838                 /* Slow path. */
839                 off = TDB_OFF_ERR;
840         }
841
842         if (unlikely(off == TDB_OFF_ERR)) {
843                 /* Slow path, need to grab more locks and search. */
844                 tdb_off_t i;
845
846                 /* Warning: this may drop the lock!  Does that on error. */
847                 num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
848                 if (num_locks == TDB_OFF_ERR)
849                         return -1;
850
851                 for (i = start; i < start + num_locks; i++) {
852                         off = entry_matches(tdb, i, h, &key, &rec);
853                         /* Empty entry or we found it? */
854                         if (off == 0 || off != TDB_OFF_ERR) {
855                                 old_bucket = i;
856                                 break;
857                         }
858                 }
859                 if (i == start + num_locks)
860                         off = 0;
861         }
862
863         if (!off) {
864                 unlock_lists(tdb, start, num_locks, F_WRLCK);
865                 tdb->ecode = TDB_ERR_NOEXIST;
866                 return -1;
867         }
868
869 delete:
870         /* This actually unlinks it. */
871         if (tdb_write_off(tdb, hash_off(tdb, old_bucket), 0) == -1)
872                 goto unlock_err;
873
874         /* Rehash anything following. */
875         for (i = hash_off(tdb, old_bucket+1);
876              i != hash_off(tdb, h + num_locks);
877              i += sizeof(tdb_off_t)) {
878                 tdb_off_t off2;
879                 uint64_t h2;
880
881                 off2 = tdb_read_off(tdb, i);
882                 if (unlikely(off2 == TDB_OFF_ERR))
883                         goto unlock_err;
884
885                 /* Maybe use a bit to indicate it is in ideal place? */
886                 h2 = hash_record(tdb, off2);
887                 /* Is it happy where it is? */
888                 if (hash_off(tdb, h2) == i)
889                         continue;
890
891                 /* Remove it. */
892                 if (tdb_write_off(tdb, i, 0) == -1)
893                         goto unlock_err;
894
895                 /* Rehash it. */
896                 if (hash_add(tdb, h2, off2) == -1)
897                         goto unlock_err;
898         }
899
900         /* Free the deleted entry. */
901         if (add_free_record(tdb, off,
902                             sizeof(struct tdb_used_record)
903                             + rec_key_length(&rec)
904                             + rec_data_length(&rec)
905                             + rec_extra_padding(&rec)) != 0)
906                 goto unlock_err;
907
908         unlock_lists(tdb, start, num_locks, F_WRLCK);
909         return 0;
910
911 unlock_err:
912         unlock_lists(tdb, start, num_locks, F_WRLCK);
913         return -1;
914 }
915
916 int tdb_close(struct tdb_context *tdb)
917 {
918         struct tdb_context **i;
919         int ret = 0;
920
921         /* FIXME:
922         if (tdb->transaction) {
923                 tdb_transaction_cancel(tdb);
924         }
925         */
926         tdb_trace(tdb, "tdb_close");
927
928         if (tdb->map_ptr) {
929                 if (tdb->flags & TDB_INTERNAL)
930                         free(tdb->map_ptr);
931                 else
932                         tdb_munmap(tdb);
933         }
934         free((char *)tdb->name);
935         if (tdb->fd != -1) {
936                 ret = close(tdb->fd);
937                 tdb->fd = -1;
938         }
939         free(tdb->lockrecs);
940
941         /* Remove from contexts list */
942         for (i = &tdbs; *i; i = &(*i)->next) {
943                 if (*i == tdb) {
944                         *i = tdb->next;
945                         break;
946                 }
947         }
948
949 #ifdef TDB_TRACE
950         close(tdb->tracefd);
951 #endif
952         free(tdb);
953
954         return ret;
955 }
956
957 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
958 {
959         return tdb->ecode;
960 }