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[thirdparty/e2fsprogs.git] / lib / ext2fs / tdb.c
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3eed36b2
TT		 1/*
2URL: svn://svnanon.samba.org/samba/branches/SAMBA_4_0/source/lib/tdb/common
3Rev: 23590
4Last Changed Date: 2007-06-22 13:36:10 -0400 (Fri, 22 Jun 2007)
106ad96d 5*/
efc6f628 6 /*
106ad96d
TT		 7 trivial database library - standalone version
8
9 Copyright (C) Andrew Tridgell 1999-2005
10 Copyright (C) Jeremy Allison 2000-2006
11 Copyright (C) Paul `Rusty' Russell 2000
efc6f628 12
106ad96d
TT		 13 ** NOTE! The following LGPL license applies to the tdb
14 ** library. This does NOT imply that all of Samba is released
15 ** under the LGPL
efc6f628 16
106ad96d
TT		 17 This library is free software; you can redistribute it and/or
18 modify it under the terms of the GNU Lesser General Public
19 License as published by the Free Software Foundation; either
20 version 2 of the License, or (at your option) any later version.
21
22 This library is distributed in the hope that it will be useful,
23 but WITHOUT ANY WARRANTY; without even the implied warranty of
24 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
25 Lesser General Public License for more details.
26
27 You should have received a copy of the GNU Lesser General Public
28 License along with this library; if not, write to the Free Software
8785aaea 29 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
106ad96d
TT		 30*/
31
32#ifdef CONFIG_STAND_ALONE
33#define HAVE_MMAP
34#define HAVE_STRDUP
35#define HAVE_SYS_MMAN_H
36#define HAVE_UTIME_H
37#define HAVE_UTIME
38#endif
d030908b 39#ifndef __FreeBSD__
ebabf2ad 40#define _XOPEN_SOURCE 600
d030908b 41#endif
106ad96d 42
d1154eb4 43#include "config.h"
106ad96d
TT		 44#include <unistd.h>
45#include <stdio.h>
46#include <stdlib.h>
47#include <stdarg.h>
48#include <stddef.h>
49#include <errno.h>
50#include <string.h>
e7cc6f7d 51#ifdef HAVE_SYS_SELECT_H
106ad96d 52#include <sys/select.h>
e7cc6f7d 53#endif
106ad96d
TT		 54#include <sys/time.h>
55#include <sys/types.h>
56#include <time.h>
57#ifdef HAVE_UTIME_H
58#include <utime.h>
59#endif
60#include <sys/stat.h>
61#include <sys/file.h>
62#include <fcntl.h>
63
64#ifdef HAVE_SYS_MMAN_H
65#include <sys/mman.h>
66#endif
67
68#ifndef MAP_FILE
69#define MAP_FILE 0
70#endif
71
72#ifndef MAP_FAILED
73#define MAP_FAILED ((void *)-1)
74#endif
75
76#ifndef HAVE_STRDUP
77#define strdup rep_strdup
78static char *rep_strdup(const char *s)
79{
80 char *ret;
81 int length;
dd3b4cc3 82
106ad96d
TT		 83 if (!s)
84 return NULL;
dd3b4cc3 85 length = strlen(s);
106ad96d
TT		 86 ret = malloc(length + 1);
87 if (ret) {
88 strncpy(ret, s, length);
89 ret[length] = '\0';
90 }
91 return ret;
92}
93#endif
94
95#ifndef PRINTF_ATTRIBUTE
96#if (__GNUC__ >= 3) && (__GNUC_MINOR__ >= 1 )
97/** Use gcc attribute to check printf fns. a1 is the 1-based index of
98 * the parameter containing the format, and a2 the index of the first
99 * argument. Note that some gcc 2.x versions don't handle this
100 * properly **/
101#define PRINTF_ATTRIBUTE(a1, a2) __attribute__ ((format (__printf__, a1, a2)))
102#else
103#define PRINTF_ATTRIBUTE(a1, a2)
104#endif
105#endif
106
3eed36b2
TT		 107typedef int bool;
108
106ad96d
TT		 109#include "tdb.h"
110
d1b75fd6
TT		 111static TDB_DATA tdb_null;
112
106ad96d
TT		 113#ifndef u32
114#define u32 unsigned
115#endif
116
106ad96d
TT		 117typedef u32 tdb_len_t;
118typedef u32 tdb_off_t;
119
120#ifndef offsetof
121#define offsetof(t,f) ((unsigned int)&((t *)0)->f)
122#endif
123
124#define TDB_MAGIC_FOOD "TDB file\n"
125#define TDB_VERSION (0x26011967 + 6)
126#define TDB_MAGIC (0x26011999U)
127#define TDB_FREE_MAGIC (~TDB_MAGIC)
128#define TDB_DEAD_MAGIC (0xFEE1DEAD)
129#define TDB_RECOVERY_MAGIC (0xf53bc0e7U)
130#define TDB_ALIGNMENT 4
131#define MIN_REC_SIZE (2*sizeof(struct list_struct) + TDB_ALIGNMENT)
132#define DEFAULT_HASH_SIZE 131
133#define FREELIST_TOP (sizeof(struct tdb_header))
134#define TDB_ALIGN(x,a) (((x) + (a)-1) & ~((a)-1))
135#define TDB_BYTEREV(x) (((((x)&0xff)<<24)|((x)&0xFF00)<<8)|(((x)>>8)&0xFF00)|((x)>>24))
136#define TDB_DEAD(r) ((r)->magic == TDB_DEAD_MAGIC)
137#define TDB_BAD_MAGIC(r) ((r)->magic != TDB_MAGIC && !TDB_DEAD(r))
138#define TDB_HASH_TOP(hash) (FREELIST_TOP + (BUCKET(hash)+1)*sizeof(tdb_off_t))
139#define TDB_HASHTABLE_SIZE(tdb) ((tdb->header.hash_size+1)*sizeof(tdb_off_t))
140#define TDB_DATA_START(hash_size) TDB_HASH_TOP(hash_size-1)
141#define TDB_RECOVERY_HEAD offsetof(struct tdb_header, recovery_start)
142#define TDB_SEQNUM_OFS offsetof(struct tdb_header, sequence_number)
143#define TDB_PAD_BYTE 0x42
144#define TDB_PAD_U32 0x42424242
145
146/* NB assumes there is a local variable called "tdb" that is the
147 * current context, also takes doubly-parenthesized print-style
148 * argument. */
149#define TDB_LOG(x) tdb->log.log_fn x
150
151/* lock offsets */
152#define GLOBAL_LOCK 0
153#define ACTIVE_LOCK 4
154#define TRANSACTION_LOCK 8
155
156/* free memory if the pointer is valid and zero the pointer */
157#ifndef SAFE_FREE
158#define SAFE_FREE(x) do { if ((x) != NULL) {free(x); (x)=NULL;} } while(0)
159#endif
160
161#define BUCKET(hash) ((hash) % tdb->header.hash_size)
162
163#define DOCONV() (tdb->flags & TDB_CONVERT)
164#define CONVERT(x) (DOCONV() ? tdb_convert(&x, sizeof(x)) : &x)
165
166
167/* the body of the database is made of one list_struct for the free space
168 plus a separate data list for each hash value */
169struct list_struct {
170 tdb_off_t next; /* offset of the next record in the list */
171 tdb_len_t rec_len; /* total byte length of record */
172 tdb_len_t key_len; /* byte length of key */
173 tdb_len_t data_len; /* byte length of data */
174 u32 full_hash; /* the full 32 bit hash of the key */
175 u32 magic; /* try to catch errors */
176 /* the following union is implied:
177 union {
178 char record[rec_len];
179 struct {
180 char key[key_len];
181 char data[data_len];
182 }
183 u32 totalsize; (tailer)
184 }
185 */
186};
187
188
189/* this is stored at the front of every database */
190struct tdb_header {
191 char magic_food[32]; /* for /etc/magic */
192 u32 version; /* version of the code */
193 u32 hash_size; /* number of hash entries */
194 tdb_off_t rwlocks; /* obsolete - kept to detect old formats */
195 tdb_off_t recovery_start; /* offset of transaction recovery region */
196 tdb_off_t sequence_number; /* used when TDB_SEQNUM is set */
197 tdb_off_t reserved[29];
198};
199
200struct tdb_lock_type {
201 int list;
202 u32 count;
203 u32 ltype;
204};
205
206struct tdb_traverse_lock {
207 struct tdb_traverse_lock *next;
208 u32 off;
209 u32 hash;
210 int lock_rw;
211};
212
213
214struct tdb_methods {
215 int (*tdb_read)(struct tdb_context *, tdb_off_t , void *, tdb_len_t , int );
216 int (*tdb_write)(struct tdb_context *, tdb_off_t, const void *, tdb_len_t);
217 void (*next_hash_chain)(struct tdb_context *, u32 *);
218 int (*tdb_oob)(struct tdb_context *, tdb_off_t , int );
219 int (*tdb_expand_file)(struct tdb_context *, tdb_off_t , tdb_off_t );
220 int (*tdb_brlock)(struct tdb_context *, tdb_off_t , int, int, int, size_t);
221};
222
223struct tdb_context {
224 char *name; /* the name of the database */
225 void *map_ptr; /* where it is currently mapped */
226 int fd; /* open file descriptor for the database */
227 tdb_len_t map_size; /* how much space has been mapped */
228 int read_only; /* opened read-only */
229 int traverse_read; /* read-only traversal */
230 struct tdb_lock_type global_lock;
231 int num_lockrecs;
232 struct tdb_lock_type *lockrecs; /* only real locks, all with count>0 */
233 enum TDB_ERROR ecode; /* error code for last tdb error */
234 struct tdb_header header; /* a cached copy of the header */
235 u32 flags; /* the flags passed to tdb_open */
236 struct tdb_traverse_lock travlocks; /* current traversal locks */
237 struct tdb_context *next; /* all tdbs to avoid multiple opens */
238 dev_t device; /* uniquely identifies this tdb */
239 ino_t inode; /* uniquely identifies this tdb */
240 struct tdb_logging_context log;
241 unsigned int (*hash_fn)(TDB_DATA *key);
242 int open_flags; /* flags used in the open - needed by reopen */
243 unsigned int num_locks; /* number of chain locks held */
244 const struct tdb_methods *methods;
245 struct tdb_transaction *transaction;
246 int page_size;
247 int max_dead_records;
3eed36b2 248 bool have_transaction_lock;
5f0164b3 249 tdb_len_t real_map_size; /* how much space has been mapped */
106ad96d
TT		 250};
251
252
253/*
254 internal prototypes
255*/
256static int tdb_munmap(struct tdb_context *tdb);
257static void tdb_mmap(struct tdb_context *tdb);
258static int tdb_lock(struct tdb_context *tdb, int list, int ltype);
259static int tdb_unlock(struct tdb_context *tdb, int list, int ltype);
260static int tdb_brlock(struct tdb_context *tdb, tdb_off_t offset, int rw_type, int lck_type, int probe, size_t len);
3eed36b2
TT		 261static int tdb_transaction_lock(struct tdb_context *tdb, int ltype);
262static int tdb_transaction_unlock(struct tdb_context *tdb);
106ad96d
TT		 263static int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len);
264static int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off);
265static int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off);
266static int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d);
267static int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d);
268static void *tdb_convert(void *buf, u32 size);
269static int tdb_free(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec);
270static tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct list_struct *rec);
271static int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d);
272static int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d);
273static int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off);
274static int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off);
275static int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec);
276static int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec);
277static int tdb_do_delete(struct tdb_context *tdb, tdb_off_t rec_ptr, struct list_struct *rec);
278static unsigned char *tdb_alloc_read(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t len);
279static int tdb_parse_data(struct tdb_context *tdb, TDB_DATA key,
280 tdb_off_t offset, tdb_len_t len,
281 int (*parser)(TDB_DATA key, TDB_DATA data,
282 void *private_data),
283 void *private_data);
284static tdb_off_t tdb_find_lock_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash, int locktype,
285 struct list_struct *rec);
286static void tdb_io_init(struct tdb_context *tdb);
287static int tdb_expand(struct tdb_context *tdb, tdb_off_t size);
3eed36b2
TT		 288static int tdb_rec_free_read(struct tdb_context *tdb, tdb_off_t off,
289 struct list_struct *rec);
106ad96d
TT		 290
291
292/* file: error.c */
293
294enum TDB_ERROR tdb_error(struct tdb_context *tdb)
295{
296 return tdb->ecode;
297}
298
299static struct tdb_errname {
300 enum TDB_ERROR ecode; const char *estring;
301} emap[] = { {TDB_SUCCESS, "Success"},
302 {TDB_ERR_CORRUPT, "Corrupt database"},
303 {TDB_ERR_IO, "IO Error"},
304 {TDB_ERR_LOCK, "Locking error"},
305 {TDB_ERR_OOM, "Out of memory"},
306 {TDB_ERR_EXISTS, "Record exists"},
307 {TDB_ERR_NOLOCK, "Lock exists on other keys"},
308 {TDB_ERR_EINVAL, "Invalid parameter"},
309 {TDB_ERR_NOEXIST, "Record does not exist"},
310 {TDB_ERR_RDONLY, "write not permitted"} };
311
312/* Error string for the last tdb error */
313const char *tdb_errorstr(struct tdb_context *tdb)
314{
315 u32 i;
316 for (i = 0; i < sizeof(emap) / sizeof(struct tdb_errname); i++)
317 if (tdb->ecode == emap[i].ecode)
318 return emap[i].estring;
319 return "Invalid error code";
320}
321
322/* file: lock.c */
323
3eed36b2
TT		 324#define TDB_MARK_LOCK 0x80000000
325
106ad96d
TT		 326/* a byte range locking function - return 0 on success
327 this functions locks/unlocks 1 byte at the specified offset.
328
329 On error, errno is also set so that errors are passed back properly
efc6f628 330 through tdb_open().
106ad96d
TT		 331
332 note that a len of zero means lock to end of file
333*/
efc6f628 334int tdb_brlock(struct tdb_context *tdb, tdb_off_t offset,
106ad96d
TT		 335 int rw_type, int lck_type, int probe, size_t len)
336{
337 struct flock fl;
338 int ret;
339
340 if (tdb->flags & TDB_NOLOCK) {
341 return 0;
342 }
343
344 if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) {
345 tdb->ecode = TDB_ERR_RDONLY;
346 return -1;
347 }
348
349 fl.l_type = rw_type;
350 fl.l_whence = SEEK_SET;
351 fl.l_start = offset;
352 fl.l_len = len;
353 fl.l_pid = 0;
354
355 do {
356 ret = fcntl(tdb->fd,lck_type,&fl);
357 } while (ret == -1 && errno == EINTR);
358
359 if (ret == -1) {
360 /* Generic lock error. errno set by fcntl.
361 * EAGAIN is an expected return from non-blocking
362 * locks. */
363 if (!probe && lck_type != F_SETLK) {
364 /* Ensure error code is set for log fun to examine. */
365 tdb->ecode = TDB_ERR_LOCK;
efc6f628 366 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %d rw_type=%d lck_type=%d len=%d\n",
106ad96d
TT		 367 tdb->fd, offset, rw_type, lck_type, (int)len));
368 }
369 return TDB_ERRCODE(TDB_ERR_LOCK, -1);
370 }
371 return 0;
372}
373
374
375/*
376 upgrade a read lock to a write lock. This needs to be handled in a
377 special way as some OSes (such as solaris) have too conservative
378 deadlock detection and claim a deadlock when progress can be
efc6f628 379 made. For those OSes we may loop for a while.
106ad96d
TT		 380*/
381int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len)
382{
383 int count = 1000;
384 while (count--) {
385 struct timeval tv;
386 if (tdb_brlock(tdb, offset, F_WRLCK, F_SETLKW, 1, len) == 0) {
387 return 0;
388 }
389 if (errno != EDEADLK) {
390 break;
391 }
392 /* sleep for as short a time as we can - more portable than usleep() */
393 tv.tv_sec = 0;
394 tv.tv_usec = 1;
395 select(0, NULL, NULL, NULL, &tv);
396 }
397 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock_upgrade failed at offset %d\n", offset));
398 return -1;
399}
400
401
402/* lock a list in the database. list -1 is the alloc list */
3eed36b2 403static int _tdb_lock(struct tdb_context *tdb, int list, int ltype, int op)
106ad96d
TT		 404{
405 struct tdb_lock_type *new_lck;
406 int i;
3eed36b2
TT		 407 bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK);
408
409 ltype &= ~TDB_MARK_LOCK;
106ad96d
TT		 410
411 /* a global lock allows us to avoid per chain locks */
efc6f628 412 if (tdb->global_lock.count &&
106ad96d
TT		 413 (ltype == tdb->global_lock.ltype || ltype == F_RDLCK)) {
414 return 0;
415 }
416
417 if (tdb->global_lock.count) {
418 return TDB_ERRCODE(TDB_ERR_LOCK, -1);
419 }
420
421 if (list < -1 || list >= (int)tdb->header.hash_size) {
efc6f628 422 TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid list %d for ltype=%d\n",
106ad96d
TT		 423 list, ltype));
424 return -1;
425 }
426 if (tdb->flags & TDB_NOLOCK)
427 return 0;
428
429 for (i=0; i<tdb->num_lockrecs; i++) {
430 if (tdb->lockrecs[i].list == list) {
431 if (tdb->lockrecs[i].count == 0) {
432 /*
433 * Can't happen, see tdb_unlock(). It should
434 * be an assert.
435 */
436 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock: "
437 "lck->count == 0 for list %d", list));
438 }
439 /*
440 * Just increment the in-memory struct, posix locks
441 * don't stack.
442 */
443 tdb->lockrecs[i].count++;
444 return 0;
445 }
446 }
447
448 new_lck = (struct tdb_lock_type *)realloc(
449 tdb->lockrecs,
450 sizeof(*tdb->lockrecs) * (tdb->num_lockrecs+1));
451 if (new_lck == NULL) {
452 errno = ENOMEM;
453 return -1;
454 }
455 tdb->lockrecs = new_lck;
456
457 /* Since fcntl locks don't nest, we do a lock for the first one,
458 and simply bump the count for future ones */
3eed36b2
TT		 459 if (!mark_lock &&
460 tdb->methods->tdb_brlock(tdb,FREELIST_TOP+4*list, ltype, op,
106ad96d 461 0, 1)) {
106ad96d
TT		 462 return -1;
463 }
464
465 tdb->num_locks++;
466
467 tdb->lockrecs[tdb->num_lockrecs].list = list;
468 tdb->lockrecs[tdb->num_lockrecs].count = 1;
469 tdb->lockrecs[tdb->num_lockrecs].ltype = ltype;
470 tdb->num_lockrecs += 1;
471
472 return 0;
473}
474
3eed36b2
TT		 475/* lock a list in the database. list -1 is the alloc list */
476int tdb_lock(struct tdb_context *tdb, int list, int ltype)
477{
478 int ret;
479 ret = _tdb_lock(tdb, list, ltype, F_SETLKW);
480 if (ret) {
481 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
482 "ltype=%d (%s)\n", list, ltype, strerror(errno)));
483 }
484 return ret;
485}
486
487/* lock a list in the database. list -1 is the alloc list. non-blocking lock */
488int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
489{
490 return _tdb_lock(tdb, list, ltype, F_SETLK);
491}
492
493
106ad96d
TT		 494/* unlock the database: returns void because it's too late for errors. */
495 /* changed to return int it may be interesting to know there
496 has been an error --simo */
497int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
498{
499 int ret = -1;
500 int i;
501 struct tdb_lock_type *lck = NULL;
3eed36b2
TT		 502 bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK);
503
504 ltype &= ~TDB_MARK_LOCK;
106ad96d
TT		 505
506 /* a global lock allows us to avoid per chain locks */
efc6f628 507 if (tdb->global_lock.count &&
106ad96d
TT		 508 (ltype == tdb->global_lock.ltype || ltype == F_RDLCK)) {
509 return 0;
510 }
511
512 if (tdb->global_lock.count) {
513 return TDB_ERRCODE(TDB_ERR_LOCK, -1);
514 }
515
516 if (tdb->flags & TDB_NOLOCK)
517 return 0;
518
519 /* Sanity checks */
520 if (list < -1 || list >= (int)tdb->header.hash_size) {
521 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: list %d invalid (%d)\n", list, tdb->header.hash_size));
522 return ret;
523 }
524
525 for (i=0; i<tdb->num_lockrecs; i++) {
526 if (tdb->lockrecs[i].list == list) {
527 lck = &tdb->lockrecs[i];
528 break;
529 }
530 }
531
532 if ((lck == NULL) || (lck->count == 0)) {
533 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n"));
534 return -1;
535 }
536
537 if (lck->count > 1) {
538 lck->count--;
539 return 0;
540 }
541
542 /*
543 * This lock has count==1 left, so we need to unlock it in the
544 * kernel. We don't bother with decrementing the in-memory array
545 * element, we're about to overwrite it with the last array element
546 * anyway.
547 */
548
3eed36b2
TT		 549 if (mark_lock) {
550 ret = 0;
551 } else {
552 ret = tdb->methods->tdb_brlock(tdb, FREELIST_TOP+4*list, F_UNLCK,
553 F_SETLKW, 0, 1);
554 }
106ad96d
TT		 555 tdb->num_locks--;
556
557 /*
558 * Shrink the array by overwriting the element just unlocked with the
559 * last array element.
560 */
561
562 if (tdb->num_lockrecs > 1) {
563 *lck = tdb->lockrecs[tdb->num_lockrecs-1];
564 }
565 tdb->num_lockrecs -= 1;
566
567 /*
568 * We don't bother with realloc when the array shrinks, but if we have
569 * a completely idle tdb we should get rid of the locked array.
570 */
571
572 if (tdb->num_lockrecs == 0) {
573 SAFE_FREE(tdb->lockrecs);
574 }
575
576 if (ret)
efc6f628 577 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: An error occurred unlocking!\n"));
106ad96d
TT		 578 return ret;
579}
580
3eed36b2
TT		 581/*
582 get the transaction lock
583 */
584int tdb_transaction_lock(struct tdb_context *tdb, int ltype)
585{
586 if (tdb->have_transaction_lock || tdb->global_lock.count) {
587 return 0;
588 }
efc6f628 589 if (tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, ltype,
3eed36b2
TT		 590 F_SETLKW, 0, 1) == -1) {
591 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_lock: failed to get transaction lock\n"));
592 tdb->ecode = TDB_ERR_LOCK;
593 return -1;
594 }
595 tdb->have_transaction_lock = 1;
596 return 0;
597}
598
599/*
600 release the transaction lock
601 */
602int tdb_transaction_unlock(struct tdb_context *tdb)
603{
604 int ret;
605 if (!tdb->have_transaction_lock) {
606 return 0;
607 }
608 ret = tdb->methods->tdb_brlock(tdb, TRANSACTION_LOCK, F_UNLCK, F_SETLKW, 0, 1);
609 if (ret == 0) {
610 tdb->have_transaction_lock = 0;
611 }
612 return ret;
613}
614
615
106ad96d
TT		 616
617
618/* lock/unlock entire database */
3eed36b2 619static int _tdb_lockall(struct tdb_context *tdb, int ltype, int op)
106ad96d 620{
3eed36b2
TT		 621 bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK);
622
623 ltype &= ~TDB_MARK_LOCK;
624
106ad96d
TT		 625 /* There are no locks on read-only dbs */
626 if (tdb->read_only || tdb->traverse_read)
627 return TDB_ERRCODE(TDB_ERR_LOCK, -1);
628
629 if (tdb->global_lock.count && tdb->global_lock.ltype == ltype) {
630 tdb->global_lock.count++;
631 return 0;
632 }
633
634 if (tdb->global_lock.count) {
635 /* a global lock of a different type exists */
636 return TDB_ERRCODE(TDB_ERR_LOCK, -1);
637 }
efc6f628 638
106ad96d
TT		 639 if (tdb->num_locks != 0) {
640 /* can't combine global and chain locks */
641 return TDB_ERRCODE(TDB_ERR_LOCK, -1);
642 }
643
3eed36b2
TT		 644 if (!mark_lock &&
645 tdb->methods->tdb_brlock(tdb, FREELIST_TOP, ltype, op,
106ad96d 646 0, 4*tdb->header.hash_size)) {
3eed36b2
TT		 647 if (op == F_SETLKW) {
648 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lockall failed (%s)\n", strerror(errno)));
649 }
106ad96d
TT		 650 return -1;
651 }
652
653 tdb->global_lock.count = 1;
654 tdb->global_lock.ltype = ltype;
655
656 return 0;
657}
658
3eed36b2
TT		 659
660
106ad96d
TT		 661/* unlock entire db */
662static int _tdb_unlockall(struct tdb_context *tdb, int ltype)
663{
3eed36b2
TT		 664 bool mark_lock = ((ltype & TDB_MARK_LOCK) == TDB_MARK_LOCK);
665
666 ltype &= ~TDB_MARK_LOCK;
667
106ad96d
TT		 668 /* There are no locks on read-only dbs */
669 if (tdb->read_only || tdb->traverse_read) {
670 return TDB_ERRCODE(TDB_ERR_LOCK, -1);
671 }
672
673 if (tdb->global_lock.ltype != ltype || tdb->global_lock.count == 0) {
674 return TDB_ERRCODE(TDB_ERR_LOCK, -1);
675 }
676
677 if (tdb->global_lock.count > 1) {
678 tdb->global_lock.count--;
679 return 0;
680 }
681
3eed36b2 682 if (!mark_lock &&
efc6f628 683 tdb->methods->tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW,
106ad96d
TT		 684 0, 4*tdb->header.hash_size)) {
685 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed (%s)\n", strerror(errno)));
686 return -1;
687 }
688
689 tdb->global_lock.count = 0;
690 tdb->global_lock.ltype = 0;
691
692 return 0;
693}
694
695/* lock entire database with write lock */
696int tdb_lockall(struct tdb_context *tdb)
697{
3eed36b2
TT		 698 return _tdb_lockall(tdb, F_WRLCK, F_SETLKW);
699}
700
701/* lock entire database with write lock - mark only */
702int tdb_lockall_mark(struct tdb_context *tdb)
703{
704 return _tdb_lockall(tdb, F_WRLCK | TDB_MARK_LOCK, F_SETLKW);
705}
706
707/* unlock entire database with write lock - unmark only */
708int tdb_lockall_unmark(struct tdb_context *tdb)
709{
710 return _tdb_unlockall(tdb, F_WRLCK | TDB_MARK_LOCK);
711}
712
055866d8 713/* lock entire database with write lock - nonblocking variant */
3eed36b2
TT		 714int tdb_lockall_nonblock(struct tdb_context *tdb)
715{
716 return _tdb_lockall(tdb, F_WRLCK, F_SETLK);
106ad96d
TT		 717}
718
719/* unlock entire database with write lock */
720int tdb_unlockall(struct tdb_context *tdb)
721{
722 return _tdb_unlockall(tdb, F_WRLCK);
723}
724
725/* lock entire database with read lock */
726int tdb_lockall_read(struct tdb_context *tdb)
727{
3eed36b2
TT		 728 return _tdb_lockall(tdb, F_RDLCK, F_SETLKW);
729}
730
055866d8 731/* lock entire database with read lock - nonblock variant */
3eed36b2
TT		 732int tdb_lockall_read_nonblock(struct tdb_context *tdb)
733{
734 return _tdb_lockall(tdb, F_RDLCK, F_SETLK);
106ad96d
TT		 735}
736
737/* unlock entire database with read lock */
738int tdb_unlockall_read(struct tdb_context *tdb)
739{
740 return _tdb_unlockall(tdb, F_RDLCK);
741}
742
743/* lock/unlock one hash chain. This is meant to be used to reduce
744 contention - it cannot guarantee how many records will be locked */
745int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key)
746{
747 return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
748}
749
3eed36b2
TT		 750/* lock/unlock one hash chain, non-blocking. This is meant to be used
751 to reduce contention - it cannot guarantee how many records will be
752 locked */
753int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key)
754{
755 return tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
756}
757
758/* mark a chain as locked without actually locking it. Warning! use with great caution! */
759int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
760{
761 return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK | TDB_MARK_LOCK);
762}
763
764/* unmark a chain as locked without actually locking it. Warning! use with great caution! */
765int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
766{
767 return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK | TDB_MARK_LOCK);
768}
769
106ad96d
TT		 770int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
771{
772 return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
773}
774
775int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
776{
777 return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
778}
779
780int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
781{
782 return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
783}
784
785
786
787/* record lock stops delete underneath */
788int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
789{
790 return off ? tdb->methods->tdb_brlock(tdb, off, F_RDLCK, F_SETLKW, 0, 1) : 0;
791}
792
793/*
794 Write locks override our own fcntl readlocks, so check it here.
795 Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
796 an error to fail to get the lock here.
797*/
798int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off)
799{
800 struct tdb_traverse_lock *i;
801 for (i = &tdb->travlocks; i; i = i->next)
802 if (i->off == off)
803 return -1;
804 return tdb->methods->tdb_brlock(tdb, off, F_WRLCK, F_SETLK, 1, 1);
805}
806
807/*
808 Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
809 an error to fail to get the lock here.
810*/
811int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
812{
813 return tdb->methods->tdb_brlock(tdb, off, F_UNLCK, F_SETLK, 0, 1);
814}
815
816/* fcntl locks don't stack: avoid unlocking someone else's */
817int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
818{
819 struct tdb_traverse_lock *i;
820 u32 count = 0;
821
822 if (off == 0)
823 return 0;
824 for (i = &tdb->travlocks; i; i = i->next)
825 if (i->off == off)
826 count++;
827 return (count == 1 ? tdb->methods->tdb_brlock(tdb, off, F_UNLCK, F_SETLKW, 0, 1) : 0);
828}
829
830/* file: io.c */
831
832/* check for an out of bounds access - if it is out of bounds then
833 see if the database has been expanded by someone else and expand
efc6f628 834 if necessary
106ad96d
TT		 835 note that "len" is the minimum length needed for the db
836*/
837static int tdb_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
838{
839 struct stat st;
840 if (len <= tdb->map_size)
841 return 0;
842 if (tdb->flags & TDB_INTERNAL) {
843 if (!probe) {
844 /* Ensure ecode is set for log fn. */
845 tdb->ecode = TDB_ERR_IO;
846 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %d beyond internal malloc size %d\n",
847 (int)len, (int)tdb->map_size));
848 }
849 return TDB_ERRCODE(TDB_ERR_IO, -1);
850 }
851
852 if (fstat(tdb->fd, &st) == -1) {
853 return TDB_ERRCODE(TDB_ERR_IO, -1);
854 }
855
856 if (st.st_size < (size_t)len) {
857 if (!probe) {
858 /* Ensure ecode is set for log fn. */
859 tdb->ecode = TDB_ERR_IO;
860 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %d beyond eof at %d\n",
861 (int)len, (int)st.st_size));
862 }
863 return TDB_ERRCODE(TDB_ERR_IO, -1);
864 }
865
866 /* Unmap, update size, remap */
867 if (tdb_munmap(tdb) == -1)
868 return TDB_ERRCODE(TDB_ERR_IO, -1);
869 tdb->map_size = st.st_size;
870 tdb_mmap(tdb);
871 return 0;
872}
873
874/* write a lump of data at a specified offset */
efc6f628 875static int tdb_write(struct tdb_context *tdb, tdb_off_t off,
106ad96d
TT		 876 const void *buf, tdb_len_t len)
877{
878 if (len == 0) {
879 return 0;
880 }
881
882 if (tdb->read_only || tdb->traverse_read) {
883 tdb->ecode = TDB_ERR_RDONLY;
884 return -1;
885 }
886
887 if (tdb->methods->tdb_oob(tdb, off + len, 0) != 0)
888 return -1;
889
890 if (tdb->map_ptr) {
891 memcpy(off + (char *)tdb->map_ptr, buf, len);
892 } else if (pwrite(tdb->fd, buf, len, off) != (ssize_t)len) {
893 /* Ensure ecode is set for log fn. */
894 tdb->ecode = TDB_ERR_IO;
895 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_write failed at %d len=%d (%s)\n",
896 off, len, strerror(errno)));
897 return TDB_ERRCODE(TDB_ERR_IO, -1);
898 }
899 return 0;
900}
901
902/* Endian conversion: we only ever deal with 4 byte quantities */
903void *tdb_convert(void *buf, u32 size)
904{
905 u32 i, *p = (u32 *)buf;
906 for (i = 0; i < size / 4; i++)
907 p[i] = TDB_BYTEREV(p[i]);
908 return buf;
909}
910
911
912/* read a lump of data at a specified offset, maybe convert */
efc6f628 913static int tdb_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
106ad96d
TT		 914 tdb_len_t len, int cv)
915{
916 if (tdb->methods->tdb_oob(tdb, off + len, 0) != 0) {
917 return -1;
918 }
919
920 if (tdb->map_ptr) {
921 memcpy(buf, off + (char *)tdb->map_ptr, len);
922 } else {
923 ssize_t ret = pread(tdb->fd, buf, len, off);
924 if (ret != (ssize_t)len) {
925 /* Ensure ecode is set for log fn. */
926 tdb->ecode = TDB_ERR_IO;
927 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_read failed at %d "
928 "len=%d ret=%d (%s) map_size=%d\n",
929 (int)off, (int)len, (int)ret, strerror(errno),
930 (int)tdb->map_size));
931 return TDB_ERRCODE(TDB_ERR_IO, -1);
932 }
933 }
934 if (cv) {
935 tdb_convert(buf, len);
936 }
937 return 0;
938}
939
940
941
942/*
943 do an unlocked scan of the hash table heads to find the next non-zero head. The value
944 will then be confirmed with the lock held
efc6f628 945*/
106ad96d
TT		 946static void tdb_next_hash_chain(struct tdb_context *tdb, u32 *chain)
947{
948 u32 h = *chain;
949 if (tdb->map_ptr) {
950 for (;h < tdb->header.hash_size;h++) {
951 if (0 != *(u32 *)(TDB_HASH_TOP(h) + (unsigned char *)tdb->map_ptr)) {
952 break;
953 }
954 }
955 } else {
956 u32 off=0;
957 for (;h < tdb->header.hash_size;h++) {
958 if (tdb_ofs_read(tdb, TDB_HASH_TOP(h), &off) != 0 || off != 0) {
959 break;
960 }
961 }
962 }
963 (*chain) = h;
964}
965
966
967int tdb_munmap(struct tdb_context *tdb)
968{
969 if (tdb->flags & TDB_INTERNAL)
970 return 0;
971
972#ifdef HAVE_MMAP
973 if (tdb->map_ptr) {
5f0164b3 974 int ret = munmap(tdb->map_ptr, tdb->real_map_size);
106ad96d
TT		 975 if (ret != 0)
976 return ret;
5f0164b3 977 tdb->real_map_size = 0;
106ad96d
TT		 978 }
979#endif
980 tdb->map_ptr = NULL;
981 return 0;
982}
983
984void tdb_mmap(struct tdb_context *tdb)
985{
986 if (tdb->flags & TDB_INTERNAL)
987 return;
988
989#ifdef HAVE_MMAP
990 if (!(tdb->flags & TDB_NOMMAP)) {
efc6f628
TT		 991 tdb->map_ptr = mmap(NULL, tdb->map_size,
992 PROT_READ|(tdb->read_only? 0:PROT_WRITE),
106ad96d
TT		 993 MAP_SHARED|MAP_FILE, tdb->fd, 0);
994
995 /*
996 * NB. When mmap fails it returns MAP_FAILED *NOT* NULL !!!!
997 */
998
999 if (tdb->map_ptr == MAP_FAILED) {
5f0164b3 1000 tdb->real_map_size = 0;
106ad96d 1001 tdb->map_ptr = NULL;
efc6f628 1002 TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_mmap failed for size %d (%s)\n",
106ad96d
TT		 1003 tdb->map_size, strerror(errno)));
1004 }
5f0164b3 1005 tdb->real_map_size = tdb->map_size;
106ad96d
TT		 1006 } else {
1007 tdb->map_ptr = NULL;
1008 }
1009#else
1010 tdb->map_ptr = NULL;
1011#endif
1012}
1013
1014/* expand a file. we prefer to use ftruncate, as that is what posix
1015 says to use for mmap expansion */
1016static int tdb_expand_file(struct tdb_context *tdb, tdb_off_t size, tdb_off_t addition)
1017{
1018 char buf[1024];
1019
1020 if (tdb->read_only || tdb->traverse_read) {
1021 tdb->ecode = TDB_ERR_RDONLY;
1022 return -1;
1023 }
1024
1025 if (ftruncate(tdb->fd, size+addition) == -1) {
1026 char b = 0;
1027 if (pwrite(tdb->fd, &b, 1, (size+addition) - 1) != 1) {
efc6f628 1028 TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file to %d failed (%s)\n",
106ad96d
TT		 1029 size+addition, strerror(errno)));
1030 return -1;
1031 }
1032 }
1033
1034 /* now fill the file with something. This ensures that the
1035 file isn't sparse, which would be very bad if we ran out of
1036 disk. This must be done with write, not via mmap */
1037 memset(buf, TDB_PAD_BYTE, sizeof(buf));
1038 while (addition) {
1039 int n = addition>sizeof(buf)?sizeof(buf):addition;
1040 int ret = pwrite(tdb->fd, buf, n, size);
1041 if (ret != n) {
efc6f628 1042 TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write of %d failed (%s)\n",
106ad96d
TT		 1043 n, strerror(errno)));
1044 return -1;
1045 }
1046 addition -= n;
1047 size += n;
1048 }
1049 return 0;
1050}
1051
1052
1053/* expand the database at least size bytes by expanding the underlying
1054 file and doing the mmap again if necessary */
1055int tdb_expand(struct tdb_context *tdb, tdb_off_t size)
1056{
1057 struct list_struct rec;
1058 tdb_off_t offset;
1059
1060 if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
1061 TDB_LOG((tdb, TDB_DEBUG_ERROR, "lock failed in tdb_expand\n"));
1062 return -1;
1063 }
1064
1065 /* must know about any previous expansions by another process */
1066 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
1067
1068 /* always make room for at least 10 more records, and round
1069 the database up to a multiple of the page size */
1070 size = TDB_ALIGN(tdb->map_size + size*10, tdb->page_size) - tdb->map_size;
1071
1072 if (!(tdb->flags & TDB_INTERNAL))
1073 tdb_munmap(tdb);
1074
1075 /*
1076 * We must ensure the file is unmapped before doing this
1077 * to ensure consistency with systems like OpenBSD where
1078 * writes and mmaps are not consistent.
1079 */
1080
1081 /* expand the file itself */
1082 if (!(tdb->flags & TDB_INTERNAL)) {
1083 if (tdb->methods->tdb_expand_file(tdb, tdb->map_size, size) != 0)
1084 goto fail;
1085 }
1086
1087 tdb->map_size += size;
1088
1089 if (tdb->flags & TDB_INTERNAL) {
1090 char *new_map_ptr = (char *)realloc(tdb->map_ptr,
1091 tdb->map_size);
1092 if (!new_map_ptr) {
1093 tdb->map_size -= size;
1094 goto fail;
1095 }
1096 tdb->map_ptr = new_map_ptr;
1097 } else {
1098 /*
1099 * We must ensure the file is remapped before adding the space
1100 * to ensure consistency with systems like OpenBSD where
1101 * writes and mmaps are not consistent.
1102 */
1103
1104 /* We're ok if the mmap fails as we'll fallback to read/write */
1105 tdb_mmap(tdb);
1106 }
1107
1108 /* form a new freelist record */
1109 memset(&rec,'\0',sizeof(rec));
1110 rec.rec_len = size - sizeof(rec);
1111
1112 /* link it into the free list */
1113 offset = tdb->map_size - size;
1114 if (tdb_free(tdb, offset, &rec) == -1)
1115 goto fail;
1116
1117 tdb_unlock(tdb, -1, F_WRLCK);
1118 return 0;
1119 fail:
1120 tdb_unlock(tdb, -1, F_WRLCK);
1121 return -1;
1122}
1123
1124/* read/write a tdb_off_t */
1125int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d)
1126{
1127 return tdb->methods->tdb_read(tdb, offset, (char*)d, sizeof(*d), DOCONV());
1128}
1129
1130int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d)
1131{
1132 tdb_off_t off = *d;
1133 return tdb->methods->tdb_write(tdb, offset, CONVERT(off), sizeof(*d));
1134}
1135
1136
1137/* read a lump of data, allocating the space for it */
1138unsigned char *tdb_alloc_read(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t len)
1139{
1140 unsigned char *buf;
1141
1142 /* some systems don't like zero length malloc */
1143 if (len == 0) {
1144 len = 1;
1145 }
1146
1147 if (!(buf = (unsigned char *)malloc(len))) {
1148 /* Ensure ecode is set for log fn. */
1149 tdb->ecode = TDB_ERR_OOM;
1150 TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_alloc_read malloc failed len=%d (%s)\n",
1151 len, strerror(errno)));
1152 return TDB_ERRCODE(TDB_ERR_OOM, buf);
1153 }
1154 if (tdb->methods->tdb_read(tdb, offset, buf, len, 0) == -1) {
1155 SAFE_FREE(buf);
1156 return NULL;
1157 }
1158 return buf;
1159}
1160
1161/* Give a piece of tdb data to a parser */
1162
1163int tdb_parse_data(struct tdb_context *tdb, TDB_DATA key,
1164 tdb_off_t offset, tdb_len_t len,
1165 int (*parser)(TDB_DATA key, TDB_DATA data,
1166 void *private_data),
1167 void *private_data)
1168{
1169 TDB_DATA data;
1170 int result;
1171
1172 data.dsize = len;
1173
1174 if ((tdb->transaction == NULL) && (tdb->map_ptr != NULL)) {
1175 /*
1176 * Optimize by avoiding the malloc/memcpy/free, point the
1177 * parser directly at the mmap area.
1178 */
1179 if (tdb->methods->tdb_oob(tdb, offset+len, 0) != 0) {
1180 return -1;
1181 }
1182 data.dptr = offset + (unsigned char *)tdb->map_ptr;
1183 return parser(key, data, private_data);
1184 }
1185
1186 if (!(data.dptr = tdb_alloc_read(tdb, offset, len))) {
1187 return -1;
1188 }
1189
1190 result = parser(key, data, private_data);
1191 free(data.dptr);
1192 return result;
1193}
1194
1195/* read/write a record */
1196int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec)
1197{
1198 if (tdb->methods->tdb_read(tdb, offset, rec, sizeof(*rec),DOCONV()) == -1)
1199 return -1;
1200 if (TDB_BAD_MAGIC(rec)) {
1201 /* Ensure ecode is set for log fn. */
1202 tdb->ecode = TDB_ERR_CORRUPT;
1203 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_rec_read bad magic 0x%x at offset=%d\n", rec->magic, offset));
1204 return TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
1205 }
1206 return tdb->methods->tdb_oob(tdb, rec->next+sizeof(*rec), 0);
1207}
1208
1209int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec)
1210{
1211 struct list_struct r = *rec;
1212 return tdb->methods->tdb_write(tdb, offset, CONVERT(r), sizeof(r));
1213}
1214
1215static const struct tdb_methods io_methods = {
1216 tdb_read,
1217 tdb_write,
1218 tdb_next_hash_chain,
1219 tdb_oob,
1220 tdb_expand_file,
1221 tdb_brlock
1222};
1223
1224/*
1225 initialise the default methods table
1226*/
1227void tdb_io_init(struct tdb_context *tdb)
1228{
1229 tdb->methods = &io_methods;
1230}
1231
1232/* file: transaction.c */
1233
1234/*
1235 transaction design:
1236
1237 - only allow a single transaction at a time per database. This makes
1238 using the transaction API simpler, as otherwise the caller would
1239 have to cope with temporary failures in transactions that conflict
1240 with other current transactions
1241
1242 - keep the transaction recovery information in the same file as the
1243 database, using a special 'transaction recovery' record pointed at
1244 by the header. This removes the need for extra journal files as
1245 used by some other databases
1246
1247 - dynamically allocated the transaction recover record, re-using it
1248 for subsequent transactions. If a larger record is needed then
1249 tdb_free() the old record to place it on the normal tdb freelist
1250 before allocating the new record
1251
1252 - during transactions, keep a linked list of writes all that have
1253 been performed by intercepting all tdb_write() calls. The hooked
1254 transaction versions of tdb_read() and tdb_write() check this
1255 linked list and try to use the elements of the list in preference
1256 to the real database.
1257
1258 - don't allow any locks to be held when a transaction starts,
1259 otherwise we can end up with deadlock (plus lack of lock nesting
1260 in posix locks would mean the lock is lost)
1261
1262 - if the caller gains a lock during the transaction but doesn't
1263 release it then fail the commit
1264
1265 - allow for nested calls to tdb_transaction_start(), re-using the
1266 existing transaction record. If the inner transaction is cancelled
1267 then a subsequent commit will fail
efc6f628 1268
106ad96d
TT		 1269 - keep a mirrored copy of the tdb hash chain heads to allow for the
1270 fast hash heads scan on traverse, updating the mirrored copy in
1271 the transaction version of tdb_write
1272
1273 - allow callers to mix transaction and non-transaction use of tdb,
1274 although once a transaction is started then an exclusive lock is
1275 gained until the transaction is committed or cancelled
1276
055866d8 1277 - the commit strategy involves first saving away all modified data
106ad96d
TT		 1278 into a linearised buffer in the transaction recovery area, then
1279 marking the transaction recovery area with a magic value to
1280 indicate a valid recovery record. In total 4 fsync/msync calls are
1281 needed per commit to prevent race conditions. It might be possible
1282 to reduce this to 3 or even 2 with some more work.
1283
1284 - check for a valid recovery record on open of the tdb, while the
1285 global lock is held. Automatically recover from the transaction
1286 recovery area if needed, then continue with the open as
1287 usual. This allows for smooth crash recovery with no administrator
1288 intervention.
1289
1290 - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
1291 still available, but no transaction recovery area is used and no
1292 fsync/msync calls are made.
1293
1294*/
1295
1296struct tdb_transaction_el {
1297 struct tdb_transaction_el *next, *prev;
1298 tdb_off_t offset;
1299 tdb_len_t length;
1300 unsigned char *data;
1301};
1302
1303/*
1304 hold the context of any current transaction
1305*/
1306struct tdb_transaction {
1307 /* we keep a mirrored copy of the tdb hash heads here so
1308 tdb_next_hash_chain() can operate efficiently */
1309 u32 *hash_heads;
1310
1311 /* the original io methods - used to do IOs to the real db */
1312 const struct tdb_methods *io_methods;
1313
1314 /* the list of transaction elements. We use a doubly linked
1315 list with a last pointer to allow us to keep the list
1316 ordered, with first element at the front of the list. It
1317 needs to be doubly linked as the read/write traversals need
1318 to be backwards, while the commit needs to be forwards */
1319 struct tdb_transaction_el *elements, *elements_last;
1320
1321 /* non-zero when an internal transaction error has
1322 occurred. All write operations will then fail until the
1323 transaction is ended */
1324 int transaction_error;
1325
1326 /* when inside a transaction we need to keep track of any
1327 nested tdb_transaction_start() calls, as these are allowed,
1328 but don't create a new transaction */
1329 int nesting;
1330
1331 /* old file size before transaction */
1332 tdb_len_t old_map_size;
1333};
1334
1335
1336/*
1337 read while in a transaction. We need to check first if the data is in our list
1338 of transaction elements, then if not do a real read
1339*/
efc6f628 1340static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
106ad96d
TT		 1341 tdb_len_t len, int cv)
1342{
1343 struct tdb_transaction_el *el;
1344
1345 /* we need to walk the list backwards to get the most recent data */
1346 for (el=tdb->transaction->elements_last;el;el=el->prev) {
1347 tdb_len_t partial;
1348
1349 if (off+len <= el->offset) {
1350 continue;
1351 }
1352 if (off >= el->offset + el->length) {
1353 continue;
1354 }
1355
1356 /* an overlapping read - needs to be split into up to
1357 2 reads and a memcpy */
1358 if (off < el->offset) {
1359 partial = el->offset - off;
1360 if (transaction_read(tdb, off, buf, partial, cv) != 0) {
1361 goto fail;
1362 }
1363 len -= partial;
1364 off += partial;
1365 buf = (void *)(partial + (char *)buf);
1366 }
1367 if (off + len <= el->offset + el->length) {
1368 partial = len;
1369 } else {
1370 partial = el->offset + el->length - off;
1371 }
1372 memcpy(buf, el->data + (off - el->offset), partial);
1373 if (cv) {
1374 tdb_convert(buf, len);
1375 }
1376 len -= partial;
1377 off += partial;
1378 buf = (void *)(partial + (char *)buf);
efc6f628 1379
106ad96d
TT		 1380 if (len != 0 && transaction_read(tdb, off, buf, len, cv) != 0) {
1381 goto fail;
1382 }
1383
1384 return 0;
1385 }
1386
1387 /* its not in the transaction elements - do a real read */
1388 return tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv);
1389
1390fail:
1391 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
1392 tdb->ecode = TDB_ERR_IO;
1393 tdb->transaction->transaction_error = 1;
1394 return -1;
1395}
1396
1397
1398/*
1399 write while in a transaction
1400*/
efc6f628 1401static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
106ad96d
TT		 1402 const void *buf, tdb_len_t len)
1403{
1404 struct tdb_transaction_el *el, *best_el=NULL;
1405
1406 if (len == 0) {
1407 return 0;
1408 }
efc6f628 1409
106ad96d
TT		 1410 /* if the write is to a hash head, then update the transaction
1411 hash heads */
1412 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
1413 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
1414 u32 chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
1415 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
1416 }
1417
1418 /* first see if we can replace an existing entry */
1419 for (el=tdb->transaction->elements_last;el;el=el->prev) {
1420 tdb_len_t partial;
1421
1422 if (best_el == NULL && off == el->offset+el->length) {
1423 best_el = el;
1424 }
1425
1426 if (off+len <= el->offset) {
1427 continue;
1428 }
1429 if (off >= el->offset + el->length) {
1430 continue;
1431 }
1432
1433 /* an overlapping write - needs to be split into up to
1434 2 writes and a memcpy */
1435 if (off < el->offset) {
1436 partial = el->offset - off;
1437 if (transaction_write(tdb, off, buf, partial) != 0) {
1438 goto fail;
1439 }
1440 len -= partial;
1441 off += partial;
1442 buf = (const void *)(partial + (const char *)buf);
1443 }
1444 if (off + len <= el->offset + el->length) {
1445 partial = len;
1446 } else {
1447 partial = el->offset + el->length - off;
1448 }
1449 memcpy(el->data + (off - el->offset), buf, partial);
1450 len -= partial;
1451 off += partial;
1452 buf = (const void *)(partial + (const char *)buf);
efc6f628 1453
106ad96d
TT		 1454 if (len != 0 && transaction_write(tdb, off, buf, len) != 0) {
1455 goto fail;
1456 }
1457
1458 return 0;
1459 }
1460
1461 /* see if we can append the new entry to an existing entry */
efc6f628 1462 if (best_el && best_el->offset + best_el->length == off &&
106ad96d
TT		 1463 (off+len < tdb->transaction->old_map_size ||
1464 off > tdb->transaction->old_map_size)) {
1465 unsigned char *data = best_el->data;
1466 el = best_el;
1467 el->data = (unsigned char *)realloc(el->data,
1468 el->length + len);
1469 if (el->data == NULL) {
1470 tdb->ecode = TDB_ERR_OOM;
1471 tdb->transaction->transaction_error = 1;
1472 el->data = data;
1473 return -1;
1474 }
1475 if (buf) {
1476 memcpy(el->data + el->length, buf, len);
1477 } else {
1478 memset(el->data + el->length, TDB_PAD_BYTE, len);
1479 }
1480 el->length += len;
1481 return 0;
1482 }
1483
1484 /* add a new entry at the end of the list */
1485 el = (struct tdb_transaction_el *)malloc(sizeof(*el));
1486 if (el == NULL) {
1487 tdb->ecode = TDB_ERR_OOM;
efc6f628 1488 tdb->transaction->transaction_error = 1;
106ad96d
TT		 1489 return -1;
1490 }
1491 el->next = NULL;
1492 el->prev = tdb->transaction->elements_last;
1493 el->offset = off;
1494 el->length = len;
1495 el->data = (unsigned char *)malloc(len);
1496 if (el->data == NULL) {
1497 free(el);
1498 tdb->ecode = TDB_ERR_OOM;
efc6f628 1499 tdb->transaction->transaction_error = 1;
106ad96d
TT		 1500 return -1;
1501 }
1502 if (buf) {
1503 memcpy(el->data, buf, len);
1504 } else {
1505 memset(el->data, TDB_PAD_BYTE, len);
1506 }
1507 if (el->prev) {
1508 el->prev->next = el;
1509 } else {
1510 tdb->transaction->elements = el;
1511 }
1512 tdb->transaction->elements_last = el;
1513 return 0;
1514
1515fail:
1516 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n", off, len));
1517 tdb->ecode = TDB_ERR_IO;
1518 tdb->transaction->transaction_error = 1;
1519 return -1;
1520}
1521
1522/*
1523 accelerated hash chain head search, using the cached hash heads
1524*/
1525static void transaction_next_hash_chain(struct tdb_context *tdb, u32 *chain)
1526{
1527 u32 h = *chain;
1528 for (;h < tdb->header.hash_size;h++) {
1529 /* the +1 takes account of the freelist */
1530 if (0 != tdb->transaction->hash_heads[h+1]) {
1531 break;
1532 }
1533 }
1534 (*chain) = h;
1535}
1536
1537/*
1538 out of bounds check during a transaction
1539*/
1540static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
1541{
1542 if (len <= tdb->map_size) {
1543 return 0;
1544 }
1545 return TDB_ERRCODE(TDB_ERR_IO, -1);
1546}
1547
1548/*
1549 transaction version of tdb_expand().
1550*/
efc6f628 1551static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
106ad96d
TT		 1552 tdb_off_t addition)
1553{
1554 /* add a write to the transaction elements, so subsequent
1555 reads see the zero data */
1556 if (transaction_write(tdb, size, NULL, addition) != 0) {
1557 return -1;
1558 }
1559
1560 return 0;
1561}
1562
1563/*
1564 brlock during a transaction - ignore them
1565*/
efc6f628 1566static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset,
106ad96d
TT		 1567 int rw_type, int lck_type, int probe, size_t len)
1568{
1569 return 0;
1570}
1571
1572static const struct tdb_methods transaction_methods = {
1573 transaction_read,
1574 transaction_write,
1575 transaction_next_hash_chain,
1576 transaction_oob,
1577 transaction_expand_file,
1578 transaction_brlock
1579};
1580
1581
1582/*
1583 start a tdb transaction. No token is returned, as only a single
1584 transaction is allowed to be pending per tdb_context
1585*/
1586int tdb_transaction_start(struct tdb_context *tdb)
1587{
1588 /* some sanity checks */
1589 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
1590 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
1591 tdb->ecode = TDB_ERR_EINVAL;
1592 return -1;
1593 }
1594
1595 /* cope with nested tdb_transaction_start() calls */
1596 if (tdb->transaction != NULL) {
1597 tdb->transaction->nesting++;
efc6f628 1598 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
106ad96d
TT		 1599 tdb->transaction->nesting));
1600 return 0;
1601 }
1602
1603 if (tdb->num_locks != 0 || tdb->global_lock.count) {
1604 /* the caller must not have any locks when starting a
1605 transaction as otherwise we'll be screwed by lack
1606 of nested locks in posix */
1607 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
1608 tdb->ecode = TDB_ERR_LOCK;
1609 return -1;
1610 }
1611
1612 if (tdb->travlocks.next != NULL) {
1613 /* you cannot use transactions inside a traverse (although you can use
1614 traverse inside a transaction) as otherwise you can end up with
1615 deadlock */
1616 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
1617 tdb->ecode = TDB_ERR_LOCK;
1618 return -1;
1619 }
1620
1621 tdb->transaction = (struct tdb_transaction *)
1622 calloc(sizeof(struct tdb_transaction), 1);
1623 if (tdb->transaction == NULL) {
1624 tdb->ecode = TDB_ERR_OOM;
1625 return -1;
1626 }
1627
1628 /* get the transaction write lock. This is a blocking lock. As
1629 discussed with Volker, there are a number of ways we could
1630 make this async, which we will probably do in the future */
3eed36b2 1631 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
106ad96d
TT		 1632 SAFE_FREE(tdb->transaction);
1633 return -1;
1634 }
efc6f628 1635
106ad96d
TT		 1636 /* get a read lock from the freelist to the end of file. This
1637 is upgraded to a write lock during the commit */
1638 if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
1639 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
1640 tdb->ecode = TDB_ERR_LOCK;
1641 goto fail;
1642 }
1643
1644 /* setup a copy of the hash table heads so the hash scan in
1645 traverse can be fast */
1646 tdb->transaction->hash_heads = (u32 *)
1647 calloc(tdb->header.hash_size+1, sizeof(u32));
1648 if (tdb->transaction->hash_heads == NULL) {
1649 tdb->ecode = TDB_ERR_OOM;
1650 goto fail;
1651 }
1652 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
1653 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
1654 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
1655 tdb->ecode = TDB_ERR_IO;
1656 goto fail;
1657 }
1658
1659 /* make sure we know about any file expansions already done by
1660 anyone else */
1661 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
1662 tdb->transaction->old_map_size = tdb->map_size;
1663
1664 /* finally hook the io methods, replacing them with
1665 transaction specific methods */
1666 tdb->transaction->io_methods = tdb->methods;
1667 tdb->methods = &transaction_methods;
1668
1669 /* by calling this transaction write here, we ensure that we don't grow the
1670 transaction linked list due to hash table updates */
efc6f628 1671 if (transaction_write(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
106ad96d
TT		 1672 TDB_HASHTABLE_SIZE(tdb)) != 0) {
1673 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to prime hash table\n"));
1674 tdb->ecode = TDB_ERR_IO;
3eed36b2 1675 tdb->methods = tdb->transaction->io_methods;
106ad96d
TT		 1676 goto fail;
1677 }
1678
1679 return 0;
efc6f628 1680
106ad96d
TT		 1681fail:
1682 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
3eed36b2 1683 tdb_transaction_unlock(tdb);
106ad96d
TT		 1684 SAFE_FREE(tdb->transaction->hash_heads);
1685 SAFE_FREE(tdb->transaction);
1686 return -1;
1687}
1688
1689
1690/*
1691 cancel the current transaction
1692*/
1693int tdb_transaction_cancel(struct tdb_context *tdb)
efc6f628 1694{
106ad96d
TT		 1695 if (tdb->transaction == NULL) {
1696 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
1697 return -1;
1698 }
1699
1700 if (tdb->transaction->nesting != 0) {
1701 tdb->transaction->transaction_error = 1;
1702 tdb->transaction->nesting--;
1703 return 0;
efc6f628 1704 }
106ad96d
TT		 1705
1706 tdb->map_size = tdb->transaction->old_map_size;
1707
1708 /* free all the transaction elements */
1709 while (tdb->transaction->elements) {
1710 struct tdb_transaction_el *el = tdb->transaction->elements;
1711 tdb->transaction->elements = el->next;
1712 free(el->data);
1713 free(el);
1714 }
1715
1716 /* remove any global lock created during the transaction */
1717 if (tdb->global_lock.count != 0) {
1718 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
1719 tdb->global_lock.count = 0;
1720 }
1721
1722 /* remove any locks created during the transaction */
1723 if (tdb->num_locks != 0) {
1724 int i;
1725 for (i=0;i<tdb->num_lockrecs;i++) {
1726 tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
1727 F_UNLCK,F_SETLKW, 0, 1);
1728 }
1729 tdb->num_locks = 0;
3eed36b2
TT		 1730 tdb->num_lockrecs = 0;
1731 SAFE_FREE(tdb->lockrecs);
106ad96d
TT		 1732 }
1733
1734 /* restore the normal io methods */
1735 tdb->methods = tdb->transaction->io_methods;
1736
1737 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
3eed36b2 1738 tdb_transaction_unlock(tdb);
106ad96d
TT		 1739 SAFE_FREE(tdb->transaction->hash_heads);
1740 SAFE_FREE(tdb->transaction);
efc6f628 1741
106ad96d
TT		 1742 return 0;
1743}
1744
1745/*
1746 sync to disk
1747*/
1748static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
efc6f628 1749{
106ad96d
TT		 1750 if (fsync(tdb->fd) != 0) {
1751 tdb->ecode = TDB_ERR_IO;
1752 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
1753 return -1;
1754 }
db40c20e 1755#if defined(HAVE_MSYNC) && defined(MS_SYNC)
106ad96d
TT		 1756 if (tdb->map_ptr) {
1757 tdb_off_t moffset = offset & ~(tdb->page_size-1);
efc6f628 1758 if (msync(moffset + (char *)tdb->map_ptr,
106ad96d
TT		 1759 length + (offset - moffset), MS_SYNC) != 0) {
1760 tdb->ecode = TDB_ERR_IO;
1761 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
1762 strerror(errno)));
1763 return -1;
1764 }
1765 }
1766#endif
1767 return 0;
1768}
1769
1770
1771/*
1772 work out how much space the linearised recovery data will consume
1773*/
1774static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
1775{
1776 struct tdb_transaction_el *el;
1777 tdb_len_t recovery_size = 0;
1778
1779 recovery_size = sizeof(u32);
1780 for (el=tdb->transaction->elements;el;el=el->next) {
1781 if (el->offset >= tdb->transaction->old_map_size) {
1782 continue;
1783 }
1784 recovery_size += 2*sizeof(tdb_off_t) + el->length;
1785 }
1786
1787 return recovery_size;
1788}
1789
1790/*
1791 allocate the recovery area, or use an existing recovery area if it is
1792 large enough
1793*/
efc6f628 1794static int tdb_recovery_allocate(struct tdb_context *tdb,
106ad96d
TT		 1795 tdb_len_t *recovery_size,
1796 tdb_off_t *recovery_offset,
1797 tdb_len_t *recovery_max_size)
1798{
1799 struct list_struct rec;
1800 const struct tdb_methods *methods = tdb->transaction->io_methods;
1801 tdb_off_t recovery_head;
1802
1803 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1804 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
1805 return -1;
1806 }
1807
1808 rec.rec_len = 0;
1809
efc6f628 1810 if (recovery_head != 0 &&
106ad96d
TT		 1811 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
1812 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
1813 return -1;
1814 }
1815
1816 *recovery_size = tdb_recovery_size(tdb);
1817
1818 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
1819 /* it fits in the existing area */
1820 *recovery_max_size = rec.rec_len;
1821 *recovery_offset = recovery_head;
1822 return 0;
1823 }
1824
1825 /* we need to free up the old recovery area, then allocate a
1826 new one at the end of the file. Note that we cannot use
1827 tdb_allocate() to allocate the new one as that might return
1828 us an area that is being currently used (as of the start of
1829 the transaction) */
1830 if (recovery_head != 0) {
1831 if (tdb_free(tdb, recovery_head, &rec) == -1) {
1832 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
1833 return -1;
1834 }
1835 }
1836
1837 /* the tdb_free() call might have increased the recovery size */
1838 *recovery_size = tdb_recovery_size(tdb);
1839
1840 /* round up to a multiple of page size */
1841 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
1842 *recovery_offset = tdb->map_size;
1843 recovery_head = *recovery_offset;
1844
efc6f628 1845 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
106ad96d
TT		 1846 (tdb->map_size - tdb->transaction->old_map_size) +
1847 sizeof(rec) + *recovery_max_size) == -1) {
1848 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
1849 return -1;
1850 }
1851
1852 /* remap the file (if using mmap) */
1853 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
1854
1855 /* we have to reset the old map size so that we don't try to expand the file
1856 again in the transaction commit, which would destroy the recovery area */
1857 tdb->transaction->old_map_size = tdb->map_size;
1858
1859 /* write the recovery header offset and sync - we can sync without a race here
1860 as the magic ptr in the recovery record has not been set */
1861 CONVERT(recovery_head);
efc6f628 1862 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
106ad96d
TT		 1863 &recovery_head, sizeof(tdb_off_t)) == -1) {
1864 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
1865 return -1;
1866 }
1867
1868 return 0;
1869}
1870
1871
1872/*
1873 setup the recovery data that will be used on a crash during commit
1874*/
efc6f628 1875static int transaction_setup_recovery(struct tdb_context *tdb,
106ad96d
TT		 1876 tdb_off_t *magic_offset)
1877{
1878 struct tdb_transaction_el *el;
1879 tdb_len_t recovery_size;
1880 unsigned char *data, *p;
1881 const struct tdb_methods *methods = tdb->transaction->io_methods;
1882 struct list_struct *rec;
1883 tdb_off_t recovery_offset, recovery_max_size;
1884 tdb_off_t old_map_size = tdb->transaction->old_map_size;
1885 u32 magic, tailer;
1886
1887 /*
1888 check that the recovery area has enough space
1889 */
efc6f628 1890 if (tdb_recovery_allocate(tdb, &recovery_size,
106ad96d
TT		 1891 &recovery_offset, &recovery_max_size) == -1) {
1892 return -1;
1893 }
1894
1895 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
1896 if (data == NULL) {
1897 tdb->ecode = TDB_ERR_OOM;
1898 return -1;
1899 }
1900
1901 rec = (struct list_struct *)data;
1902 memset(rec, 0, sizeof(*rec));
1903
1904 rec->magic = 0;
1905 rec->data_len = recovery_size;
1906 rec->rec_len = recovery_max_size;
1907 rec->key_len = old_map_size;
1908 CONVERT(rec);
1909
1910 /* build the recovery data into a single blob to allow us to do a single
1911 large write, which should be more efficient */
1912 p = data + sizeof(*rec);
1913 for (el=tdb->transaction->elements;el;el=el->next) {
1914 if (el->offset >= old_map_size) {
1915 continue;
1916 }
1917 if (el->offset + el->length > tdb->transaction->old_map_size) {
1918 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
1919 free(data);
1920 tdb->ecode = TDB_ERR_CORRUPT;
1921 return -1;
1922 }
1923 memcpy(p, &el->offset, 4);
1924 memcpy(p+4, &el->length, 4);
1925 if (DOCONV()) {
1926 tdb_convert(p, 8);
1927 }
1928 /* the recovery area contains the old data, not the
1929 new data, so we have to call the original tdb_read
1930 method to get it */
1931 if (methods->tdb_read(tdb, el->offset, p + 8, el->length, 0) != 0) {
1932 free(data);
1933 tdb->ecode = TDB_ERR_IO;
1934 return -1;
1935 }
1936 p += 8 + el->length;
1937 }
1938
1939 /* and the tailer */
1940 tailer = sizeof(*rec) + recovery_max_size;
1941 memcpy(p, &tailer, 4);
1942 CONVERT(p);
1943
1944 /* write the recovery data to the recovery area */
1945 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
1946 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
1947 free(data);
1948 tdb->ecode = TDB_ERR_IO;
1949 return -1;
1950 }
1951
1952 /* as we don't have ordered writes, we have to sync the recovery
1953 data before we update the magic to indicate that the recovery
1954 data is present */
1955 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
1956 free(data);
1957 return -1;
1958 }
1959
1960 free(data);
1961
1962 magic = TDB_RECOVERY_MAGIC;
1963 CONVERT(magic);
1964
1965 *magic_offset = recovery_offset + offsetof(struct list_struct, magic);
1966
1967 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
1968 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
1969 tdb->ecode = TDB_ERR_IO;
1970 return -1;
1971 }
1972
1973 /* ensure the recovery magic marker is on disk */
1974 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
1975 return -1;
1976 }
1977
1978 return 0;
1979}
1980
1981/*
1982 commit the current transaction
1983*/
1984int tdb_transaction_commit(struct tdb_context *tdb)
efc6f628 1985{
106ad96d
TT		 1986 const struct tdb_methods *methods;
1987 tdb_off_t magic_offset = 0;
1988 u32 zero = 0;
1989
1990 if (tdb->transaction == NULL) {
1991 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
1992 return -1;
1993 }
1994
1995 if (tdb->transaction->transaction_error) {
1996 tdb->ecode = TDB_ERR_IO;
1997 tdb_transaction_cancel(tdb);
1998 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1999 return -1;
2000 }
2001
2002 if (tdb->transaction->nesting != 0) {
2003 tdb->transaction->nesting--;
2004 return 0;
efc6f628 2005 }
106ad96d
TT		 2006
2007 /* check for a null transaction */
2008 if (tdb->transaction->elements == NULL) {
2009 tdb_transaction_cancel(tdb);
2010 return 0;
2011 }
2012
2013 methods = tdb->transaction->io_methods;
efc6f628 2014
106ad96d
TT		 2015 /* if there are any locks pending then the caller has not
2016 nested their locks properly, so fail the transaction */
2017 if (tdb->num_locks || tdb->global_lock.count) {
2018 tdb->ecode = TDB_ERR_LOCK;
2019 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: locks pending on commit\n"));
2020 tdb_transaction_cancel(tdb);
2021 return -1;
2022 }
2023
2024 /* upgrade the main transaction lock region to a write lock */
2025 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
2026 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to upgrade hash locks\n"));
2027 tdb->ecode = TDB_ERR_LOCK;
2028 tdb_transaction_cancel(tdb);
2029 return -1;
2030 }
2031
2032 /* get the global lock - this prevents new users attaching to the database
2033 during the commit */
2034 if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
2035 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: failed to get global lock\n"));
2036 tdb->ecode = TDB_ERR_LOCK;
2037 tdb_transaction_cancel(tdb);
2038 return -1;
2039 }
2040
2041 if (!(tdb->flags & TDB_NOSYNC)) {
2042 /* write the recovery data to the end of the file */
2043 if (transaction_setup_recovery(tdb, &magic_offset) == -1) {
2044 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to setup recovery data\n"));
2045 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
2046 tdb_transaction_cancel(tdb);
2047 return -1;
2048 }
2049 }
2050
2051 /* expand the file to the new size if needed */
2052 if (tdb->map_size != tdb->transaction->old_map_size) {
efc6f628
TT		 2053 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
2054 tdb->map_size -
106ad96d
TT		 2055 tdb->transaction->old_map_size) == -1) {
2056 tdb->ecode = TDB_ERR_IO;
2057 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: expansion failed\n"));
2058 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
2059 tdb_transaction_cancel(tdb);
2060 return -1;
2061 }
2062 tdb->map_size = tdb->transaction->old_map_size;
2063 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
2064 }
2065
2066 /* perform all the writes */
2067 while (tdb->transaction->elements) {
2068 struct tdb_transaction_el *el = tdb->transaction->elements;
2069
2070 if (methods->tdb_write(tdb, el->offset, el->data, el->length) == -1) {
2071 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
efc6f628 2072
106ad96d
TT		 2073 /* we've overwritten part of the data and
2074 possibly expanded the file, so we need to
2075 run the crash recovery code */
2076 tdb->methods = methods;
efc6f628 2077 tdb_transaction_recover(tdb);
106ad96d
TT		 2078
2079 tdb_transaction_cancel(tdb);
2080 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
2081
2082 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
2083 return -1;
2084 }
2085 tdb->transaction->elements = el->next;
efc6f628 2086 free(el->data);
106ad96d 2087 free(el);
efc6f628 2088 }
106ad96d
TT		 2089
2090 if (!(tdb->flags & TDB_NOSYNC)) {
2091 /* ensure the new data is on disk */
2092 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
2093 return -1;
2094 }
2095
2096 /* remove the recovery marker */
2097 if (methods->tdb_write(tdb, magic_offset, &zero, 4) == -1) {
2098 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to remove recovery magic\n"));
2099 return -1;
2100 }
2101
2102 /* ensure the recovery marker has been removed on disk */
2103 if (transaction_sync(tdb, magic_offset, 4) == -1) {
2104 return -1;
2105 }
2106 }
2107
2108 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
2109
2110 /*
2111 TODO: maybe write to some dummy hdr field, or write to magic
2112 offset without mmap, before the last sync, instead of the
2113 utime() call
2114 */
2115
2116 /* on some systems (like Linux 2.6.x) changes via mmap/msync
2117 don't change the mtime of the file, this means the file may
2118 not be backed up (as tdb rounding to block sizes means that
2119 file size changes are quite rare too). The following forces
2120 mtime changes when a transaction completes */
2121#ifdef HAVE_UTIME
2122 utime(tdb->name, NULL);
2123#endif
2124
2125 /* use a transaction cancel to free memory and remove the
2126 transaction locks */
2127 tdb_transaction_cancel(tdb);
2128 return 0;
2129}
2130
2131
2132/*
2133 recover from an aborted transaction. Must be called with exclusive
2134 database write access already established (including the global
2135 lock to prevent new processes attaching)
2136*/
2137int tdb_transaction_recover(struct tdb_context *tdb)
2138{
2139 tdb_off_t recovery_head, recovery_eof;
2140 unsigned char *data, *p;
2141 u32 zero = 0;
2142 struct list_struct rec;
2143
2144 /* find the recovery area */
2145 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
2146 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
2147 tdb->ecode = TDB_ERR_IO;
2148 return -1;
2149 }
2150
2151 if (recovery_head == 0) {
2152 /* we have never allocated a recovery record */
2153 return 0;
2154 }
2155
2156 /* read the recovery record */
efc6f628 2157 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
106ad96d 2158 sizeof(rec), DOCONV()) == -1) {
efc6f628 2159 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
106ad96d
TT		 2160 tdb->ecode = TDB_ERR_IO;
2161 return -1;
2162 }
2163
2164 if (rec.magic != TDB_RECOVERY_MAGIC) {
2165 /* there is no valid recovery data */
2166 return 0;
2167 }
2168
2169 if (tdb->read_only) {
2170 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
2171 tdb->ecode = TDB_ERR_CORRUPT;
2172 return -1;
2173 }
2174
2175 recovery_eof = rec.key_len;
2176
2177 data = (unsigned char *)malloc(rec.data_len);
2178 if (data == NULL) {
efc6f628 2179 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
106ad96d
TT		 2180 tdb->ecode = TDB_ERR_OOM;
2181 return -1;
2182 }
2183
2184 /* read the full recovery data */
2185 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
2186 rec.data_len, 0) == -1) {
efc6f628 2187 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
106ad96d
TT		 2188 tdb->ecode = TDB_ERR_IO;
2189 return -1;
2190 }
2191
2192 /* recover the file data */
2193 p = data;
2194 while (p+8 < data + rec.data_len) {
2195 u32 ofs, len;
2196 if (DOCONV()) {
2197 tdb_convert(p, 8);
2198 }
2199 memcpy(&ofs, p, 4);
2200 memcpy(&len, p+4, 4);
2201
2202 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
2203 free(data);
2204 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
2205 tdb->ecode = TDB_ERR_IO;
2206 return -1;
2207 }
2208 p += 8 + len;
2209 }
2210
2211 free(data);
2212
2213 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
2214 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
2215 tdb->ecode = TDB_ERR_IO;
2216 return -1;
2217 }
2218
2219 /* if the recovery area is after the recovered eof then remove it */
2220 if (recovery_eof <= recovery_head) {
2221 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
2222 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
2223 tdb->ecode = TDB_ERR_IO;
efc6f628 2224 return -1;
106ad96d
TT		 2225 }
2226 }
2227
2228 /* remove the recovery magic */
efc6f628 2229 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic),
106ad96d
TT		 2230 &zero) == -1) {
2231 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
2232 tdb->ecode = TDB_ERR_IO;
efc6f628 2233 return -1;
106ad96d 2234 }
efc6f628 2235
106ad96d
TT		 2236 /* reduce the file size to the old size */
2237 tdb_munmap(tdb);
2238 if (ftruncate(tdb->fd, recovery_eof) != 0) {
2239 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
2240 tdb->ecode = TDB_ERR_IO;
efc6f628 2241 return -1;
106ad96d
TT		 2242 }
2243 tdb->map_size = recovery_eof;
2244 tdb_mmap(tdb);
2245
2246 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
2247 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
2248 tdb->ecode = TDB_ERR_IO;
2249 return -1;
2250 }
2251
efc6f628 2252 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",
106ad96d
TT		 2253 recovery_eof));
2254
2255 /* all done */
2256 return 0;
2257}
2258
2259/* file: freelist.c */
2260
2261/* read a freelist record and check for simple errors */
3eed36b2 2262static int tdb_rec_free_read(struct tdb_context *tdb, tdb_off_t off, struct list_struct *rec)
106ad96d
TT		 2263{
2264 if (tdb->methods->tdb_read(tdb, off, rec, sizeof(*rec),DOCONV()) == -1)
2265 return -1;
2266
2267 if (rec->magic == TDB_MAGIC) {
2268 /* this happens when a app is showdown while deleting a record - we should
2269 not completely fail when this happens */
efc6f628 2270 TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_rec_free_read non-free magic 0x%x at offset=%d - fixing\n",
106ad96d
TT		 2271 rec->magic, off));
2272 rec->magic = TDB_FREE_MAGIC;
2273 if (tdb->methods->tdb_write(tdb, off, rec, sizeof(*rec)) == -1)
2274 return -1;
2275 }
2276
2277 if (rec->magic != TDB_FREE_MAGIC) {
2278 /* Ensure ecode is set for log fn. */
2279 tdb->ecode = TDB_ERR_CORRUPT;
efc6f628 2280 TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_rec_free_read bad magic 0x%x at offset=%d\n",
106ad96d
TT		 2281 rec->magic, off));
2282 return TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
2283 }
2284 if (tdb->methods->tdb_oob(tdb, rec->next+sizeof(*rec), 0) != 0)
2285 return -1;
2286 return 0;
2287}
2288
2289
2290
2291/* Remove an element from the freelist. Must have alloc lock. */
2292static int remove_from_freelist(struct tdb_context *tdb, tdb_off_t off, tdb_off_t next)
2293{
2294 tdb_off_t last_ptr, i;
2295
2296 /* read in the freelist top */
2297 last_ptr = FREELIST_TOP;
2298 while (tdb_ofs_read(tdb, last_ptr, &i) != -1 && i != 0) {
2299 if (i == off) {
2300 /* We've found it! */
2301 return tdb_ofs_write(tdb, last_ptr, &next);
2302 }
2303 /* Follow chain (next offset is at start of record) */
2304 last_ptr = i;
2305 }
2306 TDB_LOG((tdb, TDB_DEBUG_FATAL,"remove_from_freelist: not on list at off=%d\n", off));
2307 return TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
2308}
2309
2310
2311/* update a record tailer (must hold allocation lock) */
2312static int update_tailer(struct tdb_context *tdb, tdb_off_t offset,
2313 const struct list_struct *rec)
2314{
2315 tdb_off_t totalsize;
2316
2317 /* Offset of tailer from record header */
2318 totalsize = sizeof(*rec) + rec->rec_len;
2319 return tdb_ofs_write(tdb, offset + totalsize - sizeof(tdb_off_t),
2320 &totalsize);
2321}
2322
2323/* Add an element into the freelist. Merge adjacent records if
055866d8 2324 necessary. */
106ad96d
TT		 2325int tdb_free(struct tdb_context *tdb, tdb_off_t offset, struct list_struct *rec)
2326{
2327 tdb_off_t right, left;
2328
2329 /* Allocation and tailer lock */
2330 if (tdb_lock(tdb, -1, F_WRLCK) != 0)
2331 return -1;
2332
2333 /* set an initial tailer, so if we fail we don't leave a bogus record */
2334 if (update_tailer(tdb, offset, rec) != 0) {
2335 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: update_tailer failed!\n"));
2336 goto fail;
2337 }
2338
2339 /* Look right first (I'm an Australian, dammit) */
2340 right = offset + sizeof(*rec) + rec->rec_len;
2341 if (right + sizeof(*rec) <= tdb->map_size) {
2342 struct list_struct r;
2343
2344 if (tdb->methods->tdb_read(tdb, right, &r, sizeof(r), DOCONV()) == -1) {
2345 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: right read failed at %u\n", right));
2346 goto left;
2347 }
2348
2349 /* If it's free, expand to include it. */
2350 if (r.magic == TDB_FREE_MAGIC) {
2351 if (remove_from_freelist(tdb, right, r.next) == -1) {
2352 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: right free failed at %u\n", right));
2353 goto left;
2354 }
2355 rec->rec_len += sizeof(r) + r.rec_len;
2356 }
2357 }
2358
2359left:
2360 /* Look left */
2361 left = offset - sizeof(tdb_off_t);
2362 if (left > TDB_DATA_START(tdb->header.hash_size)) {
2363 struct list_struct l;
2364 tdb_off_t leftsize;
efc6f628 2365
106ad96d
TT		 2366 /* Read in tailer and jump back to header */
2367 if (tdb_ofs_read(tdb, left, &leftsize) == -1) {
2368 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: left offset read failed at %u\n", left));
2369 goto update;
2370 }
2371
2372 /* it could be uninitialised data */
2373 if (leftsize == 0 || leftsize == TDB_PAD_U32) {
2374 goto update;
2375 }
2376
2377 left = offset - leftsize;
2378
2379 /* Now read in record */
2380 if (tdb->methods->tdb_read(tdb, left, &l, sizeof(l), DOCONV()) == -1) {
2381 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: left read failed at %u (%u)\n", left, leftsize));
2382 goto update;
2383 }
2384
2385 /* If it's free, expand to include it. */
2386 if (l.magic == TDB_FREE_MAGIC) {
2387 if (remove_from_freelist(tdb, left, l.next) == -1) {
2388 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: left free failed at %u\n", left));
2389 goto update;
2390 } else {
2391 offset = left;
2392 rec->rec_len += leftsize;
2393 }
2394 }
2395 }
2396
2397update:
2398 if (update_tailer(tdb, offset, rec) == -1) {
2399 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free: update_tailer failed at %u\n", offset));
2400 goto fail;
2401 }
2402
2403 /* Now, prepend to free list */
2404 rec->magic = TDB_FREE_MAGIC;
2405
2406 if (tdb_ofs_read(tdb, FREELIST_TOP, &rec->next) == -1 ||
2407 tdb_rec_write(tdb, offset, rec) == -1 ||
2408 tdb_ofs_write(tdb, FREELIST_TOP, &offset) == -1) {
2409 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_free record write failed at offset=%d\n", offset));
2410 goto fail;
2411 }
2412
2413 /* And we're done. */
2414 tdb_unlock(tdb, -1, F_WRLCK);
2415 return 0;
2416
2417 fail:
2418 tdb_unlock(tdb, -1, F_WRLCK);
2419 return -1;
2420}
2421
2422
efc6f628 2423/*
106ad96d
TT		 2424 the core of tdb_allocate - called when we have decided which
2425 free list entry to use
2426 */
2427static tdb_off_t tdb_allocate_ofs(struct tdb_context *tdb, tdb_len_t length, tdb_off_t rec_ptr,
2428 struct list_struct *rec, tdb_off_t last_ptr)
2429{
2430 struct list_struct newrec;
2431 tdb_off_t newrec_ptr;
2432
2433 memset(&newrec, '\0', sizeof(newrec));
2434
2435 /* found it - now possibly split it up */
2436 if (rec->rec_len > length + MIN_REC_SIZE) {
2437 /* Length of left piece */
2438 length = TDB_ALIGN(length, TDB_ALIGNMENT);
efc6f628 2439
106ad96d
TT		 2440 /* Right piece to go on free list */
2441 newrec.rec_len = rec->rec_len - (sizeof(*rec) + length);
2442 newrec_ptr = rec_ptr + sizeof(*rec) + length;
efc6f628 2443
106ad96d
TT		 2444 /* And left record is shortened */
2445 rec->rec_len = length;
2446 } else {
2447 newrec_ptr = 0;
2448 }
efc6f628 2449
106ad96d
TT		 2450 /* Remove allocated record from the free list */
2451 if (tdb_ofs_write(tdb, last_ptr, &rec->next) == -1) {
2452 return 0;
2453 }
efc6f628 2454
106ad96d
TT		 2455 /* Update header: do this before we drop alloc
2456 lock, otherwise tdb_free() might try to
2457 merge with us, thinking we're free.
2458 (Thanks Jeremy Allison). */
2459 rec->magic = TDB_MAGIC;
2460 if (tdb_rec_write(tdb, rec_ptr, rec) == -1) {
2461 return 0;
2462 }
efc6f628 2463
106ad96d
TT		 2464 /* Did we create new block? */
2465 if (newrec_ptr) {
2466 /* Update allocated record tailer (we
2467 shortened it). */
2468 if (update_tailer(tdb, rec_ptr, rec) == -1) {
2469 return 0;
2470 }
efc6f628 2471
106ad96d
TT		 2472 /* Free new record */
2473 if (tdb_free(tdb, newrec_ptr, &newrec) == -1) {
2474 return 0;
2475 }
2476 }
efc6f628 2477
106ad96d
TT		 2478 /* all done - return the new record offset */
2479 return rec_ptr;
2480}
2481
2482/* allocate some space from the free list. The offset returned points
2483 to a unconnected list_struct within the database with room for at
2484 least length bytes of total data
2485
2486 0 is returned if the space could not be allocated
2487 */
2488tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct list_struct *rec)
2489{
2490 tdb_off_t rec_ptr, last_ptr, newrec_ptr;
2491 struct {
2492 tdb_off_t rec_ptr, last_ptr;
2493 tdb_len_t rec_len;
2494 } bestfit;
2495
2496 if (tdb_lock(tdb, -1, F_WRLCK) == -1)
2497 return 0;
2498
2499 /* Extra bytes required for tailer */
2500 length += sizeof(tdb_off_t);
2501
2502 again:
2503 last_ptr = FREELIST_TOP;
2504
2505 /* read in the freelist top */
2506 if (tdb_ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1)
2507 goto fail;
2508
2509 bestfit.rec_ptr = 0;
2510 bestfit.last_ptr = 0;
2511 bestfit.rec_len = 0;
2512
efc6f628 2513 /*
106ad96d
TT		 2514 this is a best fit allocation strategy. Originally we used
2515 a first fit strategy, but it suffered from massive fragmentation
2516 issues when faced with a slowly increasing record size.
2517 */
2518 while (rec_ptr) {
3eed36b2 2519 if (tdb_rec_free_read(tdb, rec_ptr, rec) == -1) {
106ad96d
TT		 2520 goto fail;
2521 }
2522
2523 if (rec->rec_len >= length) {
2524 if (bestfit.rec_ptr == 0 ||
2525 rec->rec_len < bestfit.rec_len) {
2526 bestfit.rec_len = rec->rec_len;
2527 bestfit.rec_ptr = rec_ptr;
2528 bestfit.last_ptr = last_ptr;
2529 /* consider a fit to be good enough if
2530 we aren't wasting more than half
2531 the space */
2532 if (bestfit.rec_len < 2*length) {
2533 break;
2534 }
2535 }
2536 }
2537
2538 /* move to the next record */
2539 last_ptr = rec_ptr;
2540 rec_ptr = rec->next;
2541 }
2542
2543 if (bestfit.rec_ptr != 0) {
3eed36b2 2544 if (tdb_rec_free_read(tdb, bestfit.rec_ptr, rec) == -1) {
106ad96d
TT		 2545 goto fail;
2546 }
2547
2548 newrec_ptr = tdb_allocate_ofs(tdb, length, bestfit.rec_ptr, rec, bestfit.last_ptr);
2549 tdb_unlock(tdb, -1, F_WRLCK);
2550 return newrec_ptr;
2551 }
2552
2553 /* we didn't find enough space. See if we can expand the
2554 database and if we can then try again */
2555 if (tdb_expand(tdb, length + sizeof(*rec)) == 0)
2556 goto again;
2557 fail:
2558 tdb_unlock(tdb, -1, F_WRLCK);
2559 return 0;
2560}
2561
2562/* file: freelistcheck.c */
2563
2564/* Check the freelist is good and contains no loops.
2565 Very memory intensive - only do this as a consistency
2566 checker. Heh heh - uses an in memory tdb as the storage
2567 for the "seen" record list. For some reason this strikes
2568 me as extremely clever as I don't have to write another tree
2569 data structure implementation :-).
2570 */
2571
2572static int seen_insert(struct tdb_context *mem_tdb, tdb_off_t rec_ptr)
2573{
2574 TDB_DATA key, data;
2575
2576 memset(&data, '\0', sizeof(data));
2577 key.dptr = (unsigned char *)&rec_ptr;
2578 key.dsize = sizeof(rec_ptr);
2579 return tdb_store(mem_tdb, key, data, TDB_INSERT);
2580}
2581
2582int tdb_validate_freelist(struct tdb_context *tdb, int *pnum_entries)
2583{
2584 struct tdb_context *mem_tdb = NULL;
2585 struct list_struct rec;
2586 tdb_off_t rec_ptr, last_ptr;
2587 int ret = -1;
2588
2589 *pnum_entries = 0;
2590
2591 mem_tdb = tdb_open("flval", tdb->header.hash_size,
2592 TDB_INTERNAL, O_RDWR, 0600);
2593 if (!mem_tdb) {
2594 return -1;
2595 }
2596
2597 if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
2598 tdb_close(mem_tdb);
2599 return 0;
2600 }
2601
2602 last_ptr = FREELIST_TOP;
2603
2604 /* Store the FREELIST_TOP record. */
2605 if (seen_insert(mem_tdb, last_ptr) == -1) {
2606 ret = TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
2607 goto fail;
2608 }
2609
2610 /* read in the freelist top */
2611 if (tdb_ofs_read(tdb, FREELIST_TOP, &rec_ptr) == -1) {
2612 goto fail;
2613 }
2614
2615 while (rec_ptr) {
2616
2617 /* If we can't store this record (we've seen it
2618 before) then the free list has a loop and must
2619 be corrupt. */
2620
2621 if (seen_insert(mem_tdb, rec_ptr)) {
2622 ret = TDB_ERRCODE(TDB_ERR_CORRUPT, -1);
2623 goto fail;
2624 }
2625
3eed36b2 2626 if (tdb_rec_free_read(tdb, rec_ptr, &rec) == -1) {
106ad96d
TT		 2627 goto fail;
2628 }
2629
2630 /* move to the next record */
2631 last_ptr = rec_ptr;
2632 rec_ptr = rec.next;
2633 *pnum_entries += 1;
2634 }
2635
2636 ret = 0;
2637
2638 fail:
2639
2640 tdb_close(mem_tdb);
2641 tdb_unlock(tdb, -1, F_WRLCK);
2642 return ret;
2643}
2644
2645/* file: traverse.c */
2646
2647/* Uses traverse lock: 0 = finish, -1 = error, other = record offset */
2648static int tdb_next_lock(struct tdb_context *tdb, struct tdb_traverse_lock *tlock,
2649 struct list_struct *rec)
2650{
2651 int want_next = (tlock->off != 0);
2652
2653 /* Lock each chain from the start one. */
2654 for (; tlock->hash < tdb->header.hash_size; tlock->hash++) {
2655 if (!tlock->off && tlock->hash != 0) {
2656 /* this is an optimisation for the common case where
2657 the hash chain is empty, which is particularly
2658 common for the use of tdb with ldb, where large
2659 hashes are used. In that case we spend most of our
2660 time in tdb_brlock(), locking empty hash chains.
efc6f628 2661
106ad96d
TT		 2662 To avoid this, we do an unlocked pre-check to see
2663 if the hash chain is empty before starting to look
2664 inside it. If it is empty then we can avoid that
2665 hash chain. If it isn't empty then we can't believe
2666 the value we get back, as we read it without a
2667 lock, so instead we get the lock and re-fetch the
2668 value below.
efc6f628 2669
106ad96d
TT		 2670 Notice that not doing this optimisation on the
2671 first hash chain is critical. We must guarantee
2672 that we have done at least one fcntl lock at the
2673 start of a search to guarantee that memory is
2674 coherent on SMP systems. If records are added by
055866d8 2675 others during the search then that's OK, and we
106ad96d
TT		 2676 could possibly miss those with this trick, but we
2677 could miss them anyway without this trick, so the
2678 semantics don't change.
efc6f628 2679
106ad96d
TT		 2680 With a non-indexed ldb search this trick gains us a
2681 factor of around 80 in speed on a linux 2.6.x
2682 system (testing using ldbtest).
2683 */
2684 tdb->methods->next_hash_chain(tdb, &tlock->hash);
2685 if (tlock->hash == tdb->header.hash_size) {
2686 continue;
2687 }
2688 }
2689
2690 if (tdb_lock(tdb, tlock->hash, tlock->lock_rw) == -1)
2691 return -1;
2692
2693 /* No previous record? Start at top of chain. */
2694 if (!tlock->off) {
2695 if (tdb_ofs_read(tdb, TDB_HASH_TOP(tlock->hash),
2696 &tlock->off) == -1)
2697 goto fail;
2698 } else {
2699 /* Otherwise unlock the previous record. */
2700 if (tdb_unlock_record(tdb, tlock->off) != 0)
2701 goto fail;
2702 }
2703
2704 if (want_next) {
2705 /* We have offset of old record: grab next */
2706 if (tdb_rec_read(tdb, tlock->off, rec) == -1)
2707 goto fail;
2708 tlock->off = rec->next;
2709 }
2710
2711 /* Iterate through chain */
2712 while( tlock->off) {
2713 tdb_off_t current;
2714 if (tdb_rec_read(tdb, tlock->off, rec) == -1)
2715 goto fail;
2716
2717 /* Detect infinite loops. From "Shlomi Yaakobovich" <Shlomi@exanet.com>. */
2718 if (tlock->off == rec->next) {
2719 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: loop detected.\n"));
2720 goto fail;
2721 }
2722
2723 if (!TDB_DEAD(rec)) {
2724 /* Woohoo: we found one! */
2725 if (tdb_lock_record(tdb, tlock->off) != 0)
2726 goto fail;
2727 return tlock->off;
2728 }
2729
2730 /* Try to clean dead ones from old traverses */
2731 current = tlock->off;
2732 tlock->off = rec->next;
efc6f628 2733 if (!(tdb->read_only || tdb->traverse_read) &&
106ad96d
TT		 2734 tdb_do_delete(tdb, current, rec) != 0)
2735 goto fail;
2736 }
2737 tdb_unlock(tdb, tlock->hash, tlock->lock_rw);
2738 want_next = 0;
2739 }
2740 /* We finished iteration without finding anything */
2741 return TDB_ERRCODE(TDB_SUCCESS, 0);
2742
2743 fail:
2744 tlock->off = 0;
2745 if (tdb_unlock(tdb, tlock->hash, tlock->lock_rw) != 0)
2746 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_next_lock: On error unlock failed!\n"));
2747 return -1;
2748}
2749
2750/* traverse the entire database - calling fn(tdb, key, data) on each element.
2751 return -1 on error or the record count traversed
2752 if fn is NULL then it is not called
2753 a non-zero return value from fn() indicates that the traversal should stop
2754 */
efc6f628 2755static int tdb_traverse_internal(struct tdb_context *tdb,
106ad96d
TT		 2756 tdb_traverse_func fn, void *private_data,
2757 struct tdb_traverse_lock *tl)
2758{
2759 TDB_DATA key, dbuf;
2760 struct list_struct rec;
2761 int ret, count = 0;
2762
055866d8 2763 /* This was in the initialization, above, but the IRIX compiler
106ad96d
TT		 2764 * did not like it. crh
2765 */
2766 tl->next = tdb->travlocks.next;
2767
2768 /* fcntl locks don't stack: beware traverse inside traverse */
2769 tdb->travlocks.next = tl;
2770
2771 /* tdb_next_lock places locks on the record returned, and its chain */
2772 while ((ret = tdb_next_lock(tdb, tl, &rec)) > 0) {
2773 count++;
2774 /* now read the full record */
efc6f628 2775 key.dptr = tdb_alloc_read(tdb, tl->off + sizeof(rec),
106ad96d
TT		 2776 rec.key_len + rec.data_len);
2777 if (!key.dptr) {
2778 ret = -1;
2779 if (tdb_unlock(tdb, tl->hash, tl->lock_rw) != 0)
2780 goto out;
2781 if (tdb_unlock_record(tdb, tl->off) != 0)
2782 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: key.dptr == NULL and unlock_record failed!\n"));
2783 goto out;
2784 }
2785 key.dsize = rec.key_len;
2786 dbuf.dptr = key.dptr + rec.key_len;
2787 dbuf.dsize = rec.data_len;
2788
2789 /* Drop chain lock, call out */
2790 if (tdb_unlock(tdb, tl->hash, tl->lock_rw) != 0) {
2791 ret = -1;
2792 SAFE_FREE(key.dptr);
2793 goto out;
2794 }
2795 if (fn && fn(tdb, key, dbuf, private_data)) {
2796 /* They want us to terminate traversal */
2797 ret = count;
2798 if (tdb_unlock_record(tdb, tl->off) != 0) {
2799 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_traverse: unlock_record failed!\n"));;
2800 ret = -1;
2801 }
2802 SAFE_FREE(key.dptr);
2803 goto out;
2804 }
2805 SAFE_FREE(key.dptr);
2806 }
2807out:
2808 tdb->travlocks.next = tl->next;
2809 if (ret < 0)
2810 return -1;
2811 else
2812 return count;
2813}
2814
2815
2816/*
2817 a write style traverse - temporarily marks the db read only
2818*/
efc6f628 2819int tdb_traverse_read(struct tdb_context *tdb,
106ad96d
TT		 2820 tdb_traverse_func fn, void *private_data)
2821{
2822 struct tdb_traverse_lock tl = { NULL, 0, 0, F_RDLCK };
2823 int ret;
3eed36b2 2824
106ad96d
TT		 2825 /* we need to get a read lock on the transaction lock here to
2826 cope with the lock ordering semantics of solaris10 */
3eed36b2 2827 if (tdb_transaction_lock(tdb, F_RDLCK)) {
106ad96d
TT		 2828 return -1;
2829 }
2830
2831 tdb->traverse_read++;
2832 ret = tdb_traverse_internal(tdb, fn, private_data, &tl);
2833 tdb->traverse_read--;
2834
3eed36b2 2835 tdb_transaction_unlock(tdb);
106ad96d
TT		 2836
2837 return ret;
2838}
2839
2840/*
2841 a write style traverse - needs to get the transaction lock to
2842 prevent deadlocks
2843*/
efc6f628 2844int tdb_traverse(struct tdb_context *tdb,
106ad96d
TT		 2845 tdb_traverse_func fn, void *private_data)
2846{
2847 struct tdb_traverse_lock tl = { NULL, 0, 0, F_WRLCK };
2848 int ret;
2849
2850 if (tdb->read_only || tdb->traverse_read) {
2851 return tdb_traverse_read(tdb, fn, private_data);
2852 }
efc6f628 2853
3eed36b2 2854 if (tdb_transaction_lock(tdb, F_WRLCK)) {
106ad96d
TT		 2855 return -1;
2856 }
2857
2858 ret = tdb_traverse_internal(tdb, fn, private_data, &tl);
2859
3eed36b2 2860 tdb_transaction_unlock(tdb);
106ad96d
TT		 2861
2862 return ret;
2863}
2864
2865
2866/* find the first entry in the database and return its key */
2867TDB_DATA tdb_firstkey(struct tdb_context *tdb)
2868{
2869 TDB_DATA key;
2870 struct list_struct rec;
2871
2872 /* release any old lock */
2873 if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0)
2874 return tdb_null;
2875 tdb->travlocks.off = tdb->travlocks.hash = 0;
2876 tdb->travlocks.lock_rw = F_RDLCK;
2877
3eed36b2 2878 /* Grab first record: locks chain and returned record. */
106ad96d
TT		 2879 if (tdb_next_lock(tdb, &tdb->travlocks, &rec) <= 0)
2880 return tdb_null;
2881 /* now read the key */
2882 key.dsize = rec.key_len;
2883 key.dptr =tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),key.dsize);
3eed36b2
TT		 2884
2885 /* Unlock the hash chain of the record we just read. */
2886 if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0)
106ad96d
TT		 2887 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_firstkey: error occurred while tdb_unlocking!\n"));
2888 return key;
2889}
2890
2891/* find the next entry in the database, returning its key */
2892TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA oldkey)
2893{
2894 u32 oldhash;
2895 TDB_DATA key = tdb_null;
2896 struct list_struct rec;
2897 unsigned char *k = NULL;
2898
2899 /* Is locked key the old key? If so, traverse will be reliable. */
2900 if (tdb->travlocks.off) {
3eed36b2 2901 if (tdb_lock(tdb,tdb->travlocks.hash,tdb->travlocks.lock_rw))
106ad96d
TT		 2902 return tdb_null;
2903 if (tdb_rec_read(tdb, tdb->travlocks.off, &rec) == -1
2904 || !(k = tdb_alloc_read(tdb,tdb->travlocks.off+sizeof(rec),
2905 rec.key_len))
2906 || memcmp(k, oldkey.dptr, oldkey.dsize) != 0) {
2907 /* No, it wasn't: unlock it and start from scratch */
2908 if (tdb_unlock_record(tdb, tdb->travlocks.off) != 0) {
2909 SAFE_FREE(k);
2910 return tdb_null;
2911 }
3eed36b2 2912 if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0) {
106ad96d
TT		 2913 SAFE_FREE(k);
2914 return tdb_null;
2915 }
2916 tdb->travlocks.off = 0;
2917 }
2918
2919 SAFE_FREE(k);
2920 }
2921
2922 if (!tdb->travlocks.off) {
2923 /* No previous element: do normal find, and lock record */
3eed36b2 2924 tdb->travlocks.off = tdb_find_lock_hash(tdb, oldkey, tdb->hash_fn(&oldkey), tdb->travlocks.lock_rw, &rec);
106ad96d
TT		 2925 if (!tdb->travlocks.off)
2926 return tdb_null;
2927 tdb->travlocks.hash = BUCKET(rec.full_hash);
2928 if (tdb_lock_record(tdb, tdb->travlocks.off) != 0) {
2929 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: lock_record failed (%s)!\n", strerror(errno)));
2930 return tdb_null;
2931 }
2932 }
2933 oldhash = tdb->travlocks.hash;
2934
2935 /* Grab next record: locks chain and returned record,
2936 unlocks old record */
2937 if (tdb_next_lock(tdb, &tdb->travlocks, &rec) > 0) {
2938 key.dsize = rec.key_len;
2939 key.dptr = tdb_alloc_read(tdb, tdb->travlocks.off+sizeof(rec),
2940 key.dsize);
2941 /* Unlock the chain of this new record */
3eed36b2 2942 if (tdb_unlock(tdb, tdb->travlocks.hash, tdb->travlocks.lock_rw) != 0)
106ad96d
TT		 2943 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n"));
2944 }
2945 /* Unlock the chain of old record */
3eed36b2 2946 if (tdb_unlock(tdb, BUCKET(oldhash), tdb->travlocks.lock_rw) != 0)
106ad96d
TT		 2947 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_nextkey: WARNING tdb_unlock failed!\n"));
2948 return key;
2949}
2950
2951/* file: dump.c */
2952
3eed36b2
TT		 2953static tdb_off_t tdb_dump_record(struct tdb_context *tdb, int hash,
2954 tdb_off_t offset)
106ad96d
TT		 2955{
2956 struct list_struct rec;
2957 tdb_off_t tailer_ofs, tailer;
2958
efc6f628 2959 if (tdb->methods->tdb_read(tdb, offset, (char *)&rec,
106ad96d
TT		 2960 sizeof(rec), DOCONV()) == -1) {
2961 printf("ERROR: failed to read record at %u\n", offset);
2962 return 0;
2963 }
2964
3eed36b2
TT		 2965 printf(" rec: hash=%d offset=0x%08x next=0x%08x rec_len=%d "
2966 "key_len=%d data_len=%d full_hash=0x%x magic=0x%x\n",
2967 hash, offset, rec.next, rec.rec_len, rec.key_len, rec.data_len,
2968 rec.full_hash, rec.magic);
106ad96d
TT		 2969
2970 tailer_ofs = offset + sizeof(rec) + rec.rec_len - sizeof(tdb_off_t);
2971
2972 if (tdb_ofs_read(tdb, tailer_ofs, &tailer) == -1) {
2973 printf("ERROR: failed to read tailer at %u\n", tailer_ofs);
2974 return rec.next;
2975 }
2976
2977 if (tailer != rec.rec_len + sizeof(rec)) {
2978 printf("ERROR: tailer does not match record! tailer=%u totalsize=%u\n",
2979 (unsigned int)tailer, (unsigned int)(rec.rec_len + sizeof(rec)));
2980 }
2981 return rec.next;
2982}
2983
2984static int tdb_dump_chain(struct tdb_context *tdb, int i)
2985{
2986 tdb_off_t rec_ptr, top;
2987
2988 top = TDB_HASH_TOP(i);
2989
2990 if (tdb_lock(tdb, i, F_WRLCK) != 0)
2991 return -1;
2992
2993 if (tdb_ofs_read(tdb, top, &rec_ptr) == -1)
2994 return tdb_unlock(tdb, i, F_WRLCK);
2995
2996 if (rec_ptr)
2997 printf("hash=%d\n", i);
2998
2999 while (rec_ptr) {
3eed36b2 3000 rec_ptr = tdb_dump_record(tdb, i, rec_ptr);
106ad96d
TT		 3001 }
3002
3003 return tdb_unlock(tdb, i, F_WRLCK);
3004}
3005
3006void tdb_dump_all(struct tdb_context *tdb)
3007{
3008 int i;
3009 for (i=0;i<tdb->header.hash_size;i++) {
3010 tdb_dump_chain(tdb, i);
3011 }
3012 printf("freelist:\n");
3013 tdb_dump_chain(tdb, -1);
3014}
3015
3016int tdb_printfreelist(struct tdb_context *tdb)
3017{
3018 int ret;
3019 long total_free = 0;
3020 tdb_off_t offset, rec_ptr;
3021 struct list_struct rec;
3022
3023 if ((ret = tdb_lock(tdb, -1, F_WRLCK)) != 0)
3024 return ret;
3025
3026 offset = FREELIST_TOP;
3027
3028 /* read in the freelist top */
3029 if (tdb_ofs_read(tdb, offset, &rec_ptr) == -1) {
3030 tdb_unlock(tdb, -1, F_WRLCK);
3031 return 0;
3032 }
3033
3034 printf("freelist top=[0x%08x]\n", rec_ptr );
3035 while (rec_ptr) {
efc6f628 3036 if (tdb->methods->tdb_read(tdb, rec_ptr, (char *)&rec,
106ad96d
TT		 3037 sizeof(rec), DOCONV()) == -1) {
3038 tdb_unlock(tdb, -1, F_WRLCK);
3039 return -1;
3040 }
3041
3042 if (rec.magic != TDB_FREE_MAGIC) {
3043 printf("bad magic 0x%08x in free list\n", rec.magic);
3044 tdb_unlock(tdb, -1, F_WRLCK);
3045 return -1;
3046 }
3047
efc6f628 3048 printf("entry offset=[0x%08x], rec.rec_len = [0x%08x (%d)] (end = 0x%08x)\n",
106ad96d
TT		 3049 rec_ptr, rec.rec_len, rec.rec_len, rec_ptr + rec.rec_len);
3050 total_free += rec.rec_len;
3051
3052 /* move to the next record */
3053 rec_ptr = rec.next;
3054 }
efc6f628 3055 printf("total rec_len = [0x%08x (%d)]\n", (int)total_free,
106ad96d
TT		 3056 (int)total_free);
3057
3058 return tdb_unlock(tdb, -1, F_WRLCK);
3059}
3060
3061/* file: tdb.c */
3062
106ad96d 3063/*
3eed36b2 3064 non-blocking increment of the tdb sequence number if the tdb has been opened using
106ad96d
TT		 3065 the TDB_SEQNUM flag
3066*/
3eed36b2 3067void tdb_increment_seqnum_nonblock(struct tdb_context *tdb)
106ad96d
TT		 3068{
3069 tdb_off_t seqnum=0;
efc6f628 3070
106ad96d
TT		 3071 if (!(tdb->flags & TDB_SEQNUM)) {
3072 return;
3073 }
3074
106ad96d
TT		 3075 /* we ignore errors from this, as we have no sane way of
3076 dealing with them.
3077 */
3078 tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
3079 seqnum++;
3080 tdb_ofs_write(tdb, TDB_SEQNUM_OFS, &seqnum);
3eed36b2
TT		 3081}
3082
3083/*
3084 increment the tdb sequence number if the tdb has been opened using
3085 the TDB_SEQNUM flag
3086*/
3087static void tdb_increment_seqnum(struct tdb_context *tdb)
3088{
3089 if (!(tdb->flags & TDB_SEQNUM)) {
3090 return;
3091 }
3092
3093 if (tdb_brlock(tdb, TDB_SEQNUM_OFS, F_WRLCK, F_SETLKW, 1, 1) != 0) {
3094 return;
3095 }
3096
3097 tdb_increment_seqnum_nonblock(tdb);
106ad96d
TT		 3098
3099 tdb_brlock(tdb, TDB_SEQNUM_OFS, F_UNLCK, F_SETLKW, 1, 1);
3100}
3101
3102static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data)
3103{
3104 return memcmp(data.dptr, key.dptr, data.dsize);
3105}
3106
3107/* Returns 0 on fail. On success, return offset of record, and fills
3108 in rec */
3109static tdb_off_t tdb_find(struct tdb_context *tdb, TDB_DATA key, u32 hash,
3110 struct list_struct *r)
3111{
3112 tdb_off_t rec_ptr;
efc6f628 3113
106ad96d
TT		 3114 /* read in the hash top */
3115 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1)
3116 return 0;
3117
3118 /* keep looking until we find the right record */
3119 while (rec_ptr) {
3120 if (tdb_rec_read(tdb, rec_ptr, r) == -1)
3121 return 0;
3122
3123 if (!TDB_DEAD(r) && hash==r->full_hash
3124 && key.dsize==r->key_len
3125 && tdb_parse_data(tdb, key, rec_ptr + sizeof(*r),
3126 r->key_len, tdb_key_compare,
3127 NULL) == 0) {
3128 return rec_ptr;
3129 }
3130 rec_ptr = r->next;
3131 }
3132 return TDB_ERRCODE(TDB_ERR_NOEXIST, 0);
3133}
3134
3135/* As tdb_find, but if you succeed, keep the lock */
3136tdb_off_t tdb_find_lock_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash, int locktype,
3137 struct list_struct *rec)
3138{
3139 u32 rec_ptr;
3140
3141 if (tdb_lock(tdb, BUCKET(hash), locktype) == -1)
3142 return 0;
3143 if (!(rec_ptr = tdb_find(tdb, key, hash, rec)))
3144 tdb_unlock(tdb, BUCKET(hash), locktype);
3145 return rec_ptr;
3146}
3147
3148
3149/* update an entry in place - this only works if the new data size
3150 is <= the old data size and the key exists.
3151 on failure return -1.
3152*/
3153static int tdb_update_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash, TDB_DATA dbuf)
3154{
3155 struct list_struct rec;
3156 tdb_off_t rec_ptr;
3157
3158 /* find entry */
3159 if (!(rec_ptr = tdb_find(tdb, key, hash, &rec)))
3160 return -1;
3161
3162 /* must be long enough key, data and tailer */
3163 if (rec.rec_len < key.dsize + dbuf.dsize + sizeof(tdb_off_t)) {
3164 tdb->ecode = TDB_SUCCESS; /* Not really an error */
3165 return -1;
3166 }
3167
3168 if (tdb->methods->tdb_write(tdb, rec_ptr + sizeof(rec) + rec.key_len,
3169 dbuf.dptr, dbuf.dsize) == -1)
3170 return -1;
3171
3172 if (dbuf.dsize != rec.data_len) {
3173 /* update size */
3174 rec.data_len = dbuf.dsize;
3175 return tdb_rec_write(tdb, rec_ptr, &rec);
3176 }
efc6f628 3177
106ad96d
TT		 3178 return 0;
3179}
3180
3181/* find an entry in the database given a key */
3182/* If an entry doesn't exist tdb_err will be set to
3183 * TDB_ERR_NOEXIST. If a key has no data attached
3184 * then the TDB_DATA will have zero length but
3185 * a non-zero pointer
3186 */
3187TDB_DATA tdb_fetch(struct tdb_context *tdb, TDB_DATA key)
3188{
3189 tdb_off_t rec_ptr;
3190 struct list_struct rec;
3191 TDB_DATA ret;
3192 u32 hash;
3193
3194 /* find which hash bucket it is in */
3195 hash = tdb->hash_fn(&key);
3196 if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec)))
3197 return tdb_null;
3198
3199 ret.dptr = tdb_alloc_read(tdb, rec_ptr + sizeof(rec) + rec.key_len,
3200 rec.data_len);
3201 ret.dsize = rec.data_len;
3202 tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK);
3203 return ret;
3204}
3205
3206/*
3207 * Find an entry in the database and hand the record's data to a parsing
3208 * function. The parsing function is executed under the chain read lock, so it
3209 * should be fast and should not block on other syscalls.
3210 *
3211 * DONT CALL OTHER TDB CALLS FROM THE PARSER, THIS MIGHT LEAD TO SEGFAULTS.
3212 *
3213 * For mmapped tdb's that do not have a transaction open it points the parsing
3214 * function directly at the mmap area, it avoids the malloc/memcpy in this
3215 * case. If a transaction is open or no mmap is available, it has to do
3216 * malloc/read/parse/free.
3217 *
3218 * This is interesting for all readers of potentially large data structures in
3219 * the tdb records, ldb indexes being one example.
3220 */
3221
3222int tdb_parse_record(struct tdb_context *tdb, TDB_DATA key,
3223 int (*parser)(TDB_DATA key, TDB_DATA data,
3224 void *private_data),
3225 void *private_data)
3226{
3227 tdb_off_t rec_ptr;
3228 struct list_struct rec;
3229 int ret;
3230 u32 hash;
3231
3232 /* find which hash bucket it is in */
3233 hash = tdb->hash_fn(&key);
3234
3235 if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec))) {
3236 return TDB_ERRCODE(TDB_ERR_NOEXIST, 0);
3237 }
3238
3239 ret = tdb_parse_data(tdb, key, rec_ptr + sizeof(rec) + rec.key_len,
3240 rec.data_len, parser, private_data);
3241
3242 tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK);
3243
3244 return ret;
3245}
3246
efc6f628 3247/* check if an entry in the database exists
106ad96d
TT		 3248
3249 note that 1 is returned if the key is found and 0 is returned if not found
3250 this doesn't match the conventions in the rest of this module, but is
3251 compatible with gdbm
3252*/
3253static int tdb_exists_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash)
3254{
3255 struct list_struct rec;
efc6f628 3256
106ad96d
TT		 3257 if (tdb_find_lock_hash(tdb, key, hash, F_RDLCK, &rec) == 0)
3258 return 0;
3259 tdb_unlock(tdb, BUCKET(rec.full_hash), F_RDLCK);
3260 return 1;
3261}
3262
3263int tdb_exists(struct tdb_context *tdb, TDB_DATA key)
3264{
3265 u32 hash = tdb->hash_fn(&key);
3266 return tdb_exists_hash(tdb, key, hash);
3267}
3268
3269/* actually delete an entry in the database given the offset */
3270int tdb_do_delete(struct tdb_context *tdb, tdb_off_t rec_ptr, struct list_struct*rec)
3271{
3272 tdb_off_t last_ptr, i;
3273 struct list_struct lastrec;
3274
3275 if (tdb->read_only || tdb->traverse_read) return -1;
3276
3277 if (tdb_write_lock_record(tdb, rec_ptr) == -1) {
3278 /* Someone traversing here: mark it as dead */
3279 rec->magic = TDB_DEAD_MAGIC;
3280 return tdb_rec_write(tdb, rec_ptr, rec);
3281 }
3282 if (tdb_write_unlock_record(tdb, rec_ptr) != 0)
3283 return -1;
3284
3285 /* find previous record in hash chain */
3286 if (tdb_ofs_read(tdb, TDB_HASH_TOP(rec->full_hash), &i) == -1)
3287 return -1;
3288 for (last_ptr = 0; i != rec_ptr; last_ptr = i, i = lastrec.next)
3289 if (tdb_rec_read(tdb, i, &lastrec) == -1)
3290 return -1;
3291
3292 /* unlink it: next ptr is at start of record. */
3293 if (last_ptr == 0)
3294 last_ptr = TDB_HASH_TOP(rec->full_hash);
3295 if (tdb_ofs_write(tdb, last_ptr, &rec->next) == -1)
3296 return -1;
3297
3298 /* recover the space */
3299 if (tdb_free(tdb, rec_ptr, rec) == -1)
3300 return -1;
3301 return 0;
3302}
3303
3304static int tdb_count_dead(struct tdb_context *tdb, u32 hash)
3305{
3306 int res = 0;
3307 tdb_off_t rec_ptr;
3308 struct list_struct rec;
efc6f628 3309
106ad96d
TT		 3310 /* read in the hash top */
3311 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1)
3312 return 0;
3313
3314 while (rec_ptr) {
3315 if (tdb_rec_read(tdb, rec_ptr, &rec) == -1)
3316 return 0;
3317
3318 if (rec.magic == TDB_DEAD_MAGIC) {
3319 res += 1;
3320 }
3321 rec_ptr = rec.next;
3322 }
3323 return res;
3324}
3325
3326/*
3327 * Purge all DEAD records from a hash chain
3328 */
3329static int tdb_purge_dead(struct tdb_context *tdb, u32 hash)
3330{
3331 int res = -1;
3332 struct list_struct rec;
3333 tdb_off_t rec_ptr;
3334
3335 if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
3336 return -1;
3337 }
efc6f628 3338
106ad96d
TT		 3339 /* read in the hash top */
3340 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1)
3341 goto fail;
3342
3343 while (rec_ptr) {
3344 tdb_off_t next;
3345
3346 if (tdb_rec_read(tdb, rec_ptr, &rec) == -1) {
3347 goto fail;
3348 }
3349
3350 next = rec.next;
3351
3352 if (rec.magic == TDB_DEAD_MAGIC
3353 && tdb_do_delete(tdb, rec_ptr, &rec) == -1) {
3354 goto fail;
3355 }
3356 rec_ptr = next;
3357 }
3358 res = 0;
3359 fail:
3360 tdb_unlock(tdb, -1, F_WRLCK);
3361 return res;
3362}
3363
3364/* delete an entry in the database given a key */
3365static int tdb_delete_hash(struct tdb_context *tdb, TDB_DATA key, u32 hash)
3366{
3367 tdb_off_t rec_ptr;
3368 struct list_struct rec;
3369 int ret;
3370
3371 if (tdb->max_dead_records != 0) {
3372
3373 /*
3374 * Allow for some dead records per hash chain, mainly for
3375 * tdb's with a very high create/delete rate like locking.tdb.
3376 */
3377
3378 if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1)
3379 return -1;
3380
3381 if (tdb_count_dead(tdb, hash) >= tdb->max_dead_records) {
3382 /*
3383 * Don't let the per-chain freelist grow too large,
3384 * delete all existing dead records
3385 */
3386 tdb_purge_dead(tdb, hash);
3387 }
3388
3389 if (!(rec_ptr = tdb_find(tdb, key, hash, &rec))) {
3390 tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
3391 return -1;
3392 }
3393
3394 /*
3395 * Just mark the record as dead.
3396 */
3397 rec.magic = TDB_DEAD_MAGIC;
3398 ret = tdb_rec_write(tdb, rec_ptr, &rec);
3399 }
3400 else {
3401 if (!(rec_ptr = tdb_find_lock_hash(tdb, key, hash, F_WRLCK,
3402 &rec)))
3403 return -1;
3404
3405 ret = tdb_do_delete(tdb, rec_ptr, &rec);
3406 }
3407
3408 if (ret == 0) {
3409 tdb_increment_seqnum(tdb);
3410 }
3411
3412 if (tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK) != 0)
3413 TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_delete: WARNING tdb_unlock failed!\n"));
3414 return ret;
3415}
3416
3417int tdb_delete(struct tdb_context *tdb, TDB_DATA key)
3418{
3419 u32 hash = tdb->hash_fn(&key);
3420 return tdb_delete_hash(tdb, key, hash);
3421}
3422
3423/*
3424 * See if we have a dead record around with enough space
3425 */
3426static tdb_off_t tdb_find_dead(struct tdb_context *tdb, u32 hash,
3427 struct list_struct *r, tdb_len_t length)
3428{
3429 tdb_off_t rec_ptr;
efc6f628 3430
106ad96d
TT		 3431 /* read in the hash top */
3432 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1)
3433 return 0;
3434
3435 /* keep looking until we find the right record */
3436 while (rec_ptr) {
3437 if (tdb_rec_read(tdb, rec_ptr, r) == -1)
3438 return 0;
3439
3440 if (TDB_DEAD(r) && r->rec_len >= length) {
3441 /*
3442 * First fit for simple coding, TODO: change to best
3443 * fit
3444 */
3445 return rec_ptr;
3446 }
3447 rec_ptr = r->next;
3448 }
3449 return 0;
3450}
3451
3452/* store an element in the database, replacing any existing element
efc6f628 3453 with the same key
106ad96d
TT		 3454
3455 return 0 on success, -1 on failure
3456*/
3457int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag)
3458{
3459 struct list_struct rec;
3460 u32 hash;
3461 tdb_off_t rec_ptr;
3462 char *p = NULL;
3463 int ret = -1;
3464
3465 if (tdb->read_only || tdb->traverse_read) {
3466 tdb->ecode = TDB_ERR_RDONLY;
3467 return -1;
3468 }
3469
3470 /* find which hash bucket it is in */
3471 hash = tdb->hash_fn(&key);
3472 if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1)
3473 return -1;
3474
3475 /* check for it existing, on insert. */
3476 if (flag == TDB_INSERT) {
3477 if (tdb_exists_hash(tdb, key, hash)) {
3478 tdb->ecode = TDB_ERR_EXISTS;
3479 goto fail;
3480 }
3481 } else {
3482 /* first try in-place update, on modify or replace. */
3483 if (tdb_update_hash(tdb, key, hash, dbuf) == 0) {
3484 goto done;
3485 }
3486 if (tdb->ecode == TDB_ERR_NOEXIST &&
3487 flag == TDB_MODIFY) {
3488 /* if the record doesn't exist and we are in TDB_MODIFY mode then
3489 we should fail the store */
3490 goto fail;
3491 }
3492 }
3493 /* reset the error code potentially set by the tdb_update() */
3494 tdb->ecode = TDB_SUCCESS;
3495
3496 /* delete any existing record - if it doesn't exist we don't
3497 care. Doing this first reduces fragmentation, and avoids
3498 coalescing with `allocated' block before it's updated. */
3499 if (flag != TDB_INSERT)
3500 tdb_delete_hash(tdb, key, hash);
3501
3502 /* Copy key+value *before* allocating free space in case malloc
3503 fails and we are left with a dead spot in the tdb. */
3504
3505 if (!(p = (char *)malloc(key.dsize + dbuf.dsize))) {
3506 tdb->ecode = TDB_ERR_OOM;
3507 goto fail;
3508 }
3509
3510 memcpy(p, key.dptr, key.dsize);
3511 if (dbuf.dsize)
3512 memcpy(p+key.dsize, dbuf.dptr, dbuf.dsize);
3513
3514 if (tdb->max_dead_records != 0) {
3515 /*
3516 * Allow for some dead records per hash chain, look if we can
3517 * find one that can hold the new record. We need enough space
3518 * for key, data and tailer. If we find one, we don't have to
3519 * consult the central freelist.
3520 */
3521 rec_ptr = tdb_find_dead(
3522 tdb, hash, &rec,
3523 key.dsize + dbuf.dsize + sizeof(tdb_off_t));
3524
3525 if (rec_ptr != 0) {
3526 rec.key_len = key.dsize;
3527 rec.data_len = dbuf.dsize;
3528 rec.full_hash = hash;
3529 rec.magic = TDB_MAGIC;
3530 if (tdb_rec_write(tdb, rec_ptr, &rec) == -1
3531 || tdb->methods->tdb_write(
3532 tdb, rec_ptr + sizeof(rec),
3533 p, key.dsize + dbuf.dsize) == -1) {
3534 goto fail;
3535 }
3536 goto done;
3537 }
3538 }
3539
3540 /*
3541 * We have to allocate some space from the freelist, so this means we
3542 * have to lock it. Use the chance to purge all the DEAD records from
3543 * the hash chain under the freelist lock.
3544 */
3545
3546 if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
3547 goto fail;
3548 }
3549
3550 if ((tdb->max_dead_records != 0)
3551 && (tdb_purge_dead(tdb, hash) == -1)) {
3552 tdb_unlock(tdb, -1, F_WRLCK);
3553 goto fail;
3554 }
3555
3556 /* we have to allocate some space */
3557 rec_ptr = tdb_allocate(tdb, key.dsize + dbuf.dsize, &rec);
3558
3559 tdb_unlock(tdb, -1, F_WRLCK);
3560
3561 if (rec_ptr == 0) {
3562 goto fail;
3563 }
3564
3565 /* Read hash top into next ptr */
3566 if (tdb_ofs_read(tdb, TDB_HASH_TOP(hash), &rec.next) == -1)
3567 goto fail;
3568
3569 rec.key_len = key.dsize;
3570 rec.data_len = dbuf.dsize;
3571 rec.full_hash = hash;
3572 rec.magic = TDB_MAGIC;
3573
3574 /* write out and point the top of the hash chain at it */
3575 if (tdb_rec_write(tdb, rec_ptr, &rec) == -1
3576 || tdb->methods->tdb_write(tdb, rec_ptr+sizeof(rec), p, key.dsize+dbuf.dsize)==-1
3577 || tdb_ofs_write(tdb, TDB_HASH_TOP(hash), &rec_ptr) == -1) {
3578 /* Need to tdb_unallocate() here */
3579 goto fail;
3580 }
3581
3582 done:
3583 ret = 0;
3584 fail:
3585 if (ret == 0) {
3586 tdb_increment_seqnum(tdb);
3587 }
3588
efc6f628 3589 SAFE_FREE(p);
106ad96d
TT		 3590 tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
3591 return ret;
3592}
3593
3594
3595/* Append to an entry. Create if not exist. */
3596int tdb_append(struct tdb_context *tdb, TDB_DATA key, TDB_DATA new_dbuf)
3597{
3598 u32 hash;
3599 TDB_DATA dbuf;
3600 int ret = -1;
3601
3602 /* find which hash bucket it is in */
3603 hash = tdb->hash_fn(&key);
3604 if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1)
3605 return -1;
3606
3607 dbuf = tdb_fetch(tdb, key);
3608
3609 if (dbuf.dptr == NULL) {
3610 dbuf.dptr = (unsigned char *)malloc(new_dbuf.dsize);
3611 } else {
3eed36b2 3612 unsigned char *new_dptr = (unsigned char *)realloc(dbuf.dptr,
106ad96d 3613 dbuf.dsize + new_dbuf.dsize);
3eed36b2
TT		 3614 if (new_dptr == NULL) {
3615 free(dbuf.dptr);
3616 }
3617 dbuf.dptr = new_dptr;
106ad96d
TT		 3618 }
3619
3620 if (dbuf.dptr == NULL) {
3621 tdb->ecode = TDB_ERR_OOM;
3622 goto failed;
3623 }
3624
3625 memcpy(dbuf.dptr + dbuf.dsize, new_dbuf.dptr, new_dbuf.dsize);
3626 dbuf.dsize += new_dbuf.dsize;
3627
3628 ret = tdb_store(tdb, key, dbuf, 0);
efc6f628 3629
106ad96d
TT		 3630failed:
3631 tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
3632 SAFE_FREE(dbuf.dptr);
3633 return ret;
3634}
3635
3636
3637/*
3638 return the name of the current tdb file
3639 useful for external logging functions
3640*/
3641const char *tdb_name(struct tdb_context *tdb)
3642{
3643 return tdb->name;
3644}
3645
3646/*
3647 return the underlying file descriptor being used by tdb, or -1
3648 useful for external routines that want to check the device/inode
3649 of the fd
3650*/
3651int tdb_fd(struct tdb_context *tdb)
3652{
3653 return tdb->fd;
3654}
3655
3656/*
3657 return the current logging function
3658 useful for external tdb routines that wish to log tdb errors
3659*/
3660tdb_log_func tdb_log_fn(struct tdb_context *tdb)
3661{
3662 return tdb->log.log_fn;
3663}
3664
3665
3666/*
3667 get the tdb sequence number. Only makes sense if the writers opened
3668 with TDB_SEQNUM set. Note that this sequence number will wrap quite
3669 quickly, so it should only be used for a 'has something changed'
3670 test, not for code that relies on the count of the number of changes
3671 made. If you want a counter then use a tdb record.
3672
3673 The aim of this sequence number is to allow for a very lightweight
3674 test of a possible tdb change.
3675*/
3676int tdb_get_seqnum(struct tdb_context *tdb)
3677{
3678 tdb_off_t seqnum=0;
3679
3680 tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
3681 return seqnum;
3682}
3683
3684int tdb_hash_size(struct tdb_context *tdb)
3685{
3686 return tdb->header.hash_size;
3687}
3688
3689size_t tdb_map_size(struct tdb_context *tdb)
3690{
3691 return tdb->map_size;
3692}
3693
3694int tdb_get_flags(struct tdb_context *tdb)
3695{
3696 return tdb->flags;
3697}
3698
3eed36b2
TT		 3699
3700/*
3701 enable sequence number handling on an open tdb
3702*/
3703void tdb_enable_seqnum(struct tdb_context *tdb)
3704{
3705 tdb->flags |= TDB_SEQNUM;
3706}
3707
106ad96d
TT		 3708/* file: open.c */
3709
3710/* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
3711static struct tdb_context *tdbs = NULL;
3712
3713
4e523bbe 3714/* This is from a hash algorithm suggested by Rogier Wolff */
106ad96d
TT		 3715static unsigned int default_tdb_hash(TDB_DATA *key)
3716{
3717 u32 value; /* Used to compute the hash value. */
3718 u32 i; /* Used to cycle through random values. */
3719
3720 /* Set the initial value from the key size. */
4e523bbe
TT		 3721 for (value = 0, i=0; i < key->dsize; i++)
3722 value = value * 256 + key->dptr[i] + (value >> 24) * 241;
106ad96d 3723
4e523bbe 3724 return value;
106ad96d
TT		 3725}
3726
3727
3728/* initialise a new database with a specified hash size */
3729static int tdb_new_database(struct tdb_context *tdb, int hash_size)
3730{
3731 struct tdb_header *newdb;
3732 int size, ret = -1;
3733
3734 /* We make it up in memory, then write it out if not internal */
3735 size = sizeof(struct tdb_header) + (hash_size+1)*sizeof(tdb_off_t);
3736 if (!(newdb = (struct tdb_header *)calloc(size, 1)))
3737 return TDB_ERRCODE(TDB_ERR_OOM, -1);
3738
3739 /* Fill in the header */
3740 newdb->version = TDB_VERSION;
3741 newdb->hash_size = hash_size;
3742 if (tdb->flags & TDB_INTERNAL) {
3743 tdb->map_size = size;
3744 tdb->map_ptr = (char *)newdb;
3745 memcpy(&tdb->header, newdb, sizeof(tdb->header));
3746 /* Convert the `ondisk' version if asked. */
3747 CONVERT(*newdb);
3748 return 0;
3749 }
3750 if (lseek(tdb->fd, 0, SEEK_SET) == -1)
3751 goto fail;
3752
3753 if (ftruncate(tdb->fd, 0) == -1)
3754 goto fail;
3755
3756 /* This creates an endian-converted header, as if read from disk */
3757 CONVERT(*newdb);
3758 memcpy(&tdb->header, newdb, sizeof(tdb->header));
3759 /* Don't endian-convert the magic food! */
3760 memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1);
3761 if (write(tdb->fd, newdb, size) != size) {
3762 ret = -1;
3763 } else {
3764 ret = 0;
3765 }
3766
3767 fail:
3768 SAFE_FREE(newdb);
3769 return ret;
3770}
3771
3772
3773
3774static int tdb_already_open(dev_t device,
3775 ino_t ino)
3776{
3777 struct tdb_context *i;
efc6f628 3778
106ad96d
TT		 3779 for (i = tdbs; i; i = i->next) {
3780 if (i->device == device && i->inode == ino) {
3781 return 1;
3782 }
3783 }
3784
3785 return 0;
3786}
3787
efc6f628 3788/* open the database, creating it if necessary
106ad96d
TT		 3789
3790 The open_flags and mode are passed straight to the open call on the
3791 database file. A flags value of O_WRONLY is invalid. The hash size
3792 is advisory, use zero for a default value.
3793
efc6f628 3794 Return is NULL on error, in which case errno is also set. Don't
106ad96d
TT		 3795 try to call tdb_error or tdb_errname, just do strerror(errno).
3796
3797 @param name may be NULL for internal databases. */
3798struct tdb_context *tdb_open(const char *name, int hash_size, int tdb_flags,
3799 int open_flags, mode_t mode)
3800{
3801 return tdb_open_ex(name, hash_size, tdb_flags, open_flags, mode, NULL, NULL);
3802}
3803
3804/* a default logging function */
3805static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...) PRINTF_ATTRIBUTE(3, 4);
3806static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...)
3807{
3808}
3809
3810
3811struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
3812 int open_flags, mode_t mode,
3813 const struct tdb_logging_context *log_ctx,
3814 tdb_hash_func hash_fn)
3815{
3816 struct tdb_context *tdb;
3817 struct stat st;
3818 int rev = 0, locked = 0;
3819 unsigned char *vp;
3820 u32 vertest;
3821
3822 if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
3823 /* Can't log this */
3824 errno = ENOMEM;
3825 goto fail;
3826 }
3827 tdb_io_init(tdb);
3828 tdb->fd = -1;
3829 tdb->name = NULL;
3830 tdb->map_ptr = NULL;
3831 tdb->flags = tdb_flags;
3832 tdb->open_flags = open_flags;
3833 if (log_ctx) {
3834 tdb->log = *log_ctx;
3835 } else {
3836 tdb->log.log_fn = null_log_fn;
3837 tdb->log.log_private = NULL;
3838 }
3839 tdb->hash_fn = hash_fn ? hash_fn : default_tdb_hash;
3840
3841 /* cache the page size */
24d364fc 3842 tdb->page_size = sysconf(_SC_PAGESIZE);
106ad96d
TT		 3843 if (tdb->page_size <= 0) {
3844 tdb->page_size = 0x2000;
3845 }
3846
3847 if ((open_flags & O_ACCMODE) == O_WRONLY) {
3848 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: can't open tdb %s write-only\n",
3849 name));
3850 errno = EINVAL;
3851 goto fail;
3852 }
efc6f628 3853
106ad96d
TT		 3854 if (hash_size == 0)
3855 hash_size = DEFAULT_HASH_SIZE;
3856 if ((open_flags & O_ACCMODE) == O_RDONLY) {
3857 tdb->read_only = 1;
3858 /* read only databases don't do locking or clear if first */
3859 tdb->flags |= TDB_NOLOCK;
3860 tdb->flags &= ~TDB_CLEAR_IF_FIRST;
3861 }
3862
3863 /* internal databases don't mmap or lock, and start off cleared */
3864 if (tdb->flags & TDB_INTERNAL) {
3865 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
3866 tdb->flags &= ~TDB_CLEAR_IF_FIRST;
3867 if (tdb_new_database(tdb, hash_size) != 0) {
3868 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: tdb_new_database failed!"));
3869 goto fail;
3870 }
3871 goto internal;
3872 }
3873
3874 if ((tdb->fd = open(name, open_flags, mode)) == -1) {
3875 TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_open_ex: could not open file %s: %s\n",
3876 name, strerror(errno)));
3877 goto fail; /* errno set by open(2) */
3878 }
3879
3880 /* ensure there is only one process initialising at once */
3881 if (tdb->methods->tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
3882 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to get global lock on %s: %s\n",
3883 name, strerror(errno)));
3884 goto fail; /* errno set by tdb_brlock */
3885 }
3886
3887 /* we need to zero database if we are the only one with it open */
3888 if ((tdb_flags & TDB_CLEAR_IF_FIRST) &&
3889 (locked = (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_WRLCK, F_SETLK, 0, 1) == 0))) {
3890 open_flags |= O_CREAT;
3891 if (ftruncate(tdb->fd, 0) == -1) {
3892 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
3893 "failed to truncate %s: %s\n",
3894 name, strerror(errno)));
3895 goto fail; /* errno set by ftruncate */
3896 }
3897 }
3898
3899 if (read(tdb->fd, &tdb->header, sizeof(tdb->header)) != sizeof(tdb->header)
3900 || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0
3901 || (tdb->header.version != TDB_VERSION
3902 && !(rev = (tdb->header.version==TDB_BYTEREV(TDB_VERSION))))) {
3903 /* its not a valid database - possibly initialise it */
3904 if (!(open_flags & O_CREAT) || tdb_new_database(tdb, hash_size) == -1) {
3905 errno = EIO; /* ie bad format or something */
3906 goto fail;
3907 }
3908 rev = (tdb->flags & TDB_CONVERT);
3909 }
3910 vp = (unsigned char *)&tdb->header.version;
3911 vertest = (((u32)vp[0]) << 24) | (((u32)vp[1]) << 16) |
3912 (((u32)vp[2]) << 8) | (u32)vp[3];
3913 tdb->flags |= (vertest==TDB_VERSION) ? TDB_BIGENDIAN : 0;
3914 if (!rev)
3915 tdb->flags &= ~TDB_CONVERT;
3916 else {
3917 tdb->flags |= TDB_CONVERT;
3918 tdb_convert(&tdb->header, sizeof(tdb->header));
3919 }
3920 if (fstat(tdb->fd, &st) == -1)
3921 goto fail;
3922
3923 if (tdb->header.rwlocks != 0) {
3924 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: spinlocks no longer supported\n"));
3925 goto fail;
3926 }
3927
3928 /* Is it already in the open list? If so, fail. */
3929 if (tdb_already_open(st.st_dev, st.st_ino)) {
3930 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
3931 "%s (%d,%d) is already open in this process\n",
3932 name, (int)st.st_dev, (int)st.st_ino));
3933 errno = EBUSY;
3934 goto fail;
3935 }
3936
3937 if (!(tdb->name = (char *)strdup(name))) {
3938 errno = ENOMEM;
3939 goto fail;
3940 }
3941
3942 tdb->map_size = st.st_size;
3943 tdb->device = st.st_dev;
3944 tdb->inode = st.st_ino;
3945 tdb->max_dead_records = 0;
3946 tdb_mmap(tdb);
3947 if (locked) {
3948 if (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_UNLCK, F_SETLK, 0, 1) == -1) {
3949 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
3950 "failed to take ACTIVE_LOCK on %s: %s\n",
3951 name, strerror(errno)));
3952 goto fail;
3953 }
3954
3955 }
3956
3957 /* We always need to do this if the CLEAR_IF_FIRST flag is set, even if
3958 we didn't get the initial exclusive lock as we need to let all other
3959 users know we're using it. */
3960
3961 if (tdb_flags & TDB_CLEAR_IF_FIRST) {
3962 /* leave this lock in place to indicate it's in use */
3963 if (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)
3964 goto fail;
3965 }
3966
3967 /* if needed, run recovery */
3968 if (tdb_transaction_recover(tdb) == -1) {
3969 goto fail;
3970 }
3971
3972 internal:
3973 /* Internal (memory-only) databases skip all the code above to
3974 * do with disk files, and resume here by releasing their
3975 * global lock and hooking into the active list. */
3976 if (tdb->methods->tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1) == -1)
3977 goto fail;
3978 tdb->next = tdbs;
3979 tdbs = tdb;
3980 return tdb;
3981
3982 fail:
3983 { int save_errno = errno;
3984
3985 if (!tdb)
3986 return NULL;
efc6f628 3987
106ad96d
TT		 3988 if (tdb->map_ptr) {
3989 if (tdb->flags & TDB_INTERNAL)
3990 SAFE_FREE(tdb->map_ptr);
3991 else
3992 tdb_munmap(tdb);
3993 }
3994 SAFE_FREE(tdb->name);
3995 if (tdb->fd != -1)
3996 if (close(tdb->fd) != 0)
3997 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to close tdb->fd on error!\n"));
3998 SAFE_FREE(tdb);
3999 errno = save_errno;
4000 return NULL;
4001 }
4002}
4003
4004/*
4005 * Set the maximum number of dead records per hash chain
4006 */
4007
4008void tdb_set_max_dead(struct tdb_context *tdb, int max_dead)
4009{
4010 tdb->max_dead_records = max_dead;
4011}
4012
4013/**
4014 * Close a database.
4015 *
4016 * @returns -1 for error; 0 for success.
4017 **/
4018int tdb_close(struct tdb_context *tdb)
4019{
4020 struct tdb_context **i;
4021 int ret = 0;
4022
4023 if (tdb->transaction) {
4024 tdb_transaction_cancel(tdb);
4025 }
4026
4027 if (tdb->map_ptr) {
4028 if (tdb->flags & TDB_INTERNAL)
4029 SAFE_FREE(tdb->map_ptr);
4030 else
4031 tdb_munmap(tdb);
4032 }
4033 SAFE_FREE(tdb->name);
4034 if (tdb->fd != -1)
4035 ret = close(tdb->fd);
4036 SAFE_FREE(tdb->lockrecs);
4037
4038 /* Remove from contexts list */
4039 for (i = &tdbs; *i; i = &(*i)->next) {
4040 if (*i == tdb) {
4041 *i = tdb->next;
4042 break;
4043 }
4044 }
4045
4046 memset(tdb, 0, sizeof(*tdb));
4047 SAFE_FREE(tdb);
4048
4049 return ret;
4050}
4051
055866d8 4052/* register a logging function */
106ad96d
TT		 4053void tdb_set_logging_function(struct tdb_context *tdb,
4054 const struct tdb_logging_context *log_ctx)
4055{
4056 tdb->log = *log_ctx;
4057}
4058
4059void *tdb_get_logging_private(struct tdb_context *tdb)
4060{
4061 return tdb->log.log_private;
4062}
4063
4064/* reopen a tdb - this can be used after a fork to ensure that we have an independent
4065 seek pointer from our parent and to re-establish locks */
4066int tdb_reopen(struct tdb_context *tdb)
4067{
4068 struct stat st;
4069
4070 if (tdb->flags & TDB_INTERNAL) {
4071 return 0; /* Nothing to do. */
4072 }
4073
4074 if (tdb->num_locks != 0 || tdb->global_lock.count) {
4075 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed with locks held\n"));
4076 goto fail;
4077 }
4078
4079 if (tdb->transaction != 0) {
4080 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed inside a transaction\n"));
4081 goto fail;
4082 }
4083
4084 if (tdb_munmap(tdb) != 0) {
4085 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: munmap failed (%s)\n", strerror(errno)));
4086 goto fail;
4087 }
4088 if (close(tdb->fd) != 0)
4089 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: WARNING closing tdb->fd failed!\n"));
4090 tdb->fd = open(tdb->name, tdb->open_flags & ~(O_CREAT|O_TRUNC), 0);
4091 if (tdb->fd == -1) {
4092 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: open failed (%s)\n", strerror(errno)));
4093 goto fail;
4094 }
efc6f628 4095 if ((tdb->flags & TDB_CLEAR_IF_FIRST) &&
106ad96d
TT		 4096 (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)) {
4097 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: failed to obtain active lock\n"));
4098 goto fail;
4099 }
4100 if (fstat(tdb->fd, &st) != 0) {
4101 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: fstat failed (%s)\n", strerror(errno)));
4102 goto fail;
4103 }
4104 if (st.st_ino != tdb->inode || st.st_dev != tdb->device) {
4105 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: file dev/inode has changed!\n"));
4106 goto fail;
4107 }
4108 tdb_mmap(tdb);
4109
4110 return 0;
4111
4112fail:
4113 tdb_close(tdb);
4114 return -1;
4115}
4116
4117/* reopen all tdb's */
4118int tdb_reopen_all(int parent_longlived)
4119{
4120 struct tdb_context *tdb;
4121
4122 for (tdb=tdbs; tdb; tdb = tdb->next) {
4123 /*
4124 * If the parent is longlived (ie. a
4125 * parent daemon architecture), we know
4126 * it will keep it's active lock on a
4127 * tdb opened with CLEAR_IF_FIRST. Thus
4128 * for child processes we don't have to
4129 * add an active lock. This is essential
4130 * to improve performance on systems that
4131 * keep POSIX locks as a non-scalable data
4132 * structure in the kernel.
4133 */
4134 if (parent_longlived) {
4135 /* Ensure no clear-if-first. */
4136 tdb->flags &= ~TDB_CLEAR_IF_FIRST;
4137 }
4138
4139 if (tdb_reopen(tdb) != 0)
4140 return -1;
4141 }
4142
4143 return 0;
4144}
c866515f
DW		 4145
4146/**
4147 * Flush a database file from the page cache.
4148 **/
4149int tdb_flush(struct tdb_context *tdb)
4150{
4151 if (tdb->fd != -1)
4152 return fsync(tdb->fd);
4153 return 0;
4154}
Unnamed repository; edit this file 'description' to name the repository.