TDB2: Goodbye TDB2, Hello NTDB.

This renames everything from tdb2 to ntdb: importantly, we no longer
use the tdb_ namespace, so you can link against both ntdb and tdb if
you want to.

This also enables building of standalone ntdb by the autobuild script.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 657 insertions, 0 deletions

diff --git a/lib/ntdb/private.h b/lib/ntdb/private.h
new file mode 100644
index 0000000000..1cf9b7aca4
--- /dev/null
+++ b/lib/ntdb/private.h
@@ -0,0 +1,657 @@
+#ifndef NTDB_PRIVATE_H
+#define NTDB_PRIVATE_H
+/*
+  Trivial Database 2: private types and prototypes
+  Copyright (C) Rusty Russell 2010
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 3 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "config.h"
+#ifndef HAVE_CCAN
+#error You need ccan to build ntdb!
+#endif
+#include "ntdb.h"
+#include <ccan/compiler/compiler.h>
+#include <ccan/likely/likely.h>
+#include <ccan/endian/endian.h>
+
+#ifdef HAVE_LIBREPLACE
+#include "replace.h"
+#include "system/filesys.h"
+#include "system/time.h"
+#include "system/shmem.h"
+#include "system/select.h"
+#include "system/wait.h"
+#else
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <utime.h>
+#include <unistd.h>
+#endif
+
+#ifndef TEST_IT
+#define TEST_IT(cond)
+#endif
+
+/* #define NTDB_TRACE 1 */
+
+#ifndef __STRING
+#define __STRING(x)    #x
+#endif
+
+#ifndef __STRINGSTRING
+#define __STRINGSTRING(x) __STRING(x)
+#endif
+
+#ifndef __location__
+#define __location__ __FILE__ ":" __STRINGSTRING(__LINE__)
+#endif
+
+typedef uint64_t ntdb_len_t;
+typedef uint64_t ntdb_off_t;
+
+#define NTDB_MAGIC_FOOD "NTDB file\n"
+#define NTDB_VERSION ((uint64_t)(0x26011967 + 7))
+#define NTDB_USED_MAGIC ((uint64_t)0x1999)
+#define NTDB_HTABLE_MAGIC ((uint64_t)0x1888)
+#define NTDB_CHAIN_MAGIC ((uint64_t)0x1777)
+#define NTDB_FTABLE_MAGIC ((uint64_t)0x1666)
+#define NTDB_CAP_MAGIC ((uint64_t)0x1555)
+#define NTDB_FREE_MAGIC ((uint64_t)0xFE)
+#define NTDB_HASH_MAGIC (0xA1ABE11A01092008ULL)
+#define NTDB_RECOVERY_MAGIC (0xf53bc0e7ad124589ULL)
+#define NTDB_RECOVERY_INVALID_MAGIC (0x0ULL)
+
+/* Capability bits. */
+#define NTDB_CAP_TYPE_MASK	0x1FFFFFFFFFFFFFFFULL
+#define NTDB_CAP_NOCHECK		0x8000000000000000ULL
+#define NTDB_CAP_NOWRITE		0x4000000000000000ULL
+#define NTDB_CAP_NOOPEN		0x2000000000000000ULL
+
+#define NTDB_OFF_IS_ERR(off) unlikely(off >= (ntdb_off_t)(long)NTDB_ERR_LAST)
+#define NTDB_OFF_TO_ERR(off) ((enum NTDB_ERROR)(long)(off))
+#define NTDB_ERR_TO_OFF(ecode) ((ntdb_off_t)(long)(ecode))
+
+/* Packing errors into pointers and v.v. */
+#define NTDB_PTR_IS_ERR(ptr)						\
+	unlikely((unsigned long)(ptr) >= (unsigned long)NTDB_ERR_LAST)
+#define NTDB_PTR_ERR(p) ((enum NTDB_ERROR)(long)(p))
+#define NTDB_ERR_PTR(err) ((void *)(long)(err))
+
+/* Common case of returning true, false or -ve error. */
+typedef int ntdb_bool_err;
+
+/* Prevent others from opening the file. */
+#define NTDB_OPEN_LOCK 0
+/* Expanding file. */
+#define NTDB_EXPANSION_LOCK 2
+/* Doing a transaction. */
+#define NTDB_TRANSACTION_LOCK 8
+/* Hash chain locks. */
+#define NTDB_HASH_LOCK_START 64
+
+/* Range for hash locks. */
+#define NTDB_HASH_LOCK_RANGE_BITS 30
+#define NTDB_HASH_LOCK_RANGE (1 << NTDB_HASH_LOCK_RANGE_BITS)
+
+/* We have 1024 entries in the top level. */
+#define NTDB_TOPLEVEL_HASH_BITS 10
+/* And 64 entries in each sub-level: thus 64 bits exactly after 9 levels. */
+#define NTDB_SUBLEVEL_HASH_BITS 6
+/* And 8 entries in each group, ie 8 groups per sublevel. */
+#define NTDB_HASH_GROUP_BITS 3
+/* This is currently 10: beyond this we chain. */
+#define NTDB_MAX_LEVELS (1+(64-NTDB_TOPLEVEL_HASH_BITS) / NTDB_SUBLEVEL_HASH_BITS)
+
+/* Extend file by least 100 times larger than needed. */
+#define NTDB_EXTENSION_FACTOR 100
+
+/* We steal bits from the offsets to store hash info. */
+#define NTDB_OFF_HASH_GROUP_MASK ((1ULL << NTDB_HASH_GROUP_BITS) - 1)
+/* We steal this many upper bits, giving a maximum offset of 64 exabytes. */
+#define NTDB_OFF_UPPER_STEAL 8
+#define   NTDB_OFF_UPPER_STEAL_EXTRA 7
+/* The bit number where we store extra hash bits. */
+#define NTDB_OFF_HASH_EXTRA_BIT 57
+#define NTDB_OFF_UPPER_STEAL_SUBHASH_BIT 56
+
+/* Additional features we understand.  Currently: none. */
+#define NTDB_FEATURE_MASK ((uint64_t)0)
+
+/* The bit number where we store the extra hash bits. */
+/* Convenience mask to get actual offset. */
+#define NTDB_OFF_MASK							\
+	(((1ULL << (64 - NTDB_OFF_UPPER_STEAL)) - 1) - NTDB_OFF_HASH_GROUP_MASK)
+
+/* How many buckets in a free list: see size_to_bucket(). */
+#define NTDB_FREE_BUCKETS (64 - NTDB_OFF_UPPER_STEAL)
+
+/* We have to be able to fit a free record here. */
+#define NTDB_MIN_DATA_LEN						\
+	(sizeof(struct ntdb_free_record) - sizeof(struct ntdb_used_record))
+
+/* Indicates this entry is not on an flist (can happen during coalescing) */
+#define NTDB_FTABLE_NONE ((1ULL << NTDB_OFF_UPPER_STEAL) - 1)
+
+struct ntdb_used_record {
+	/* For on-disk compatibility, we avoid bitfields:
+	   magic: 16,        (highest)
+	   key_len_bits: 5,
+	   extra_padding: 32
+	   hash_bits: 11
+	*/
+        uint64_t magic_and_meta;
+	/* The bottom key_len_bits*2 are key length, rest is data length. */
+        uint64_t key_and_data_len;
+};
+
+static inline unsigned rec_key_bits(const struct ntdb_used_record *r)
+{
+	return ((r->magic_and_meta >> 43) & ((1 << 5)-1)) * 2;
+}
+
+static inline uint64_t rec_key_length(const struct ntdb_used_record *r)
+{
+	return r->key_and_data_len & ((1ULL << rec_key_bits(r)) - 1);
+}
+
+static inline uint64_t rec_data_length(const struct ntdb_used_record *r)
+{
+	return r->key_and_data_len >> rec_key_bits(r);
+}
+
+static inline uint64_t rec_extra_padding(const struct ntdb_used_record *r)
+{
+	return (r->magic_and_meta >> 11) & 0xFFFFFFFF;
+}
+
+static inline uint32_t rec_hash(const struct ntdb_used_record *r)
+{
+	return r->magic_and_meta & ((1 << 11) - 1);
+}
+
+static inline uint16_t rec_magic(const struct ntdb_used_record *r)
+{
+	return (r->magic_and_meta >> 48);
+}
+
+struct ntdb_free_record {
+        uint64_t magic_and_prev; /* NTDB_OFF_UPPER_STEAL bits magic, then prev */
+        uint64_t ftable_and_len; /* Len not counting these two fields. */
+	/* This is why the minimum record size is 8 bytes.  */
+	uint64_t next;
+};
+
+static inline uint64_t frec_prev(const struct ntdb_free_record *f)
+{
+	return f->magic_and_prev & ((1ULL << (64 - NTDB_OFF_UPPER_STEAL)) - 1);
+}
+
+static inline uint64_t frec_magic(const struct ntdb_free_record *f)
+{
+	return f->magic_and_prev >> (64 - NTDB_OFF_UPPER_STEAL);
+}
+
+static inline uint64_t frec_len(const struct ntdb_free_record *f)
+{
+	return f->ftable_and_len & ((1ULL << (64 - NTDB_OFF_UPPER_STEAL))-1);
+}
+
+static inline unsigned frec_ftable(const struct ntdb_free_record *f)
+{
+	return f->ftable_and_len >> (64 - NTDB_OFF_UPPER_STEAL);
+}
+
+struct ntdb_recovery_record {
+	uint64_t magic;
+	/* Length of record (add this header to get total length). */
+	uint64_t max_len;
+	/* Length used. */
+	uint64_t len;
+	/* Old length of file before transaction. */
+	uint64_t eof;
+};
+
+/* If we bottom out of the subhashes, we chain. */
+struct ntdb_chain {
+	ntdb_off_t rec[1 << NTDB_HASH_GROUP_BITS];
+	ntdb_off_t next;
+};
+
+/* this is stored at the front of every database */
+struct ntdb_header {
+	char magic_food[64]; /* for /etc/magic */
+	/* FIXME: Make me 32 bit? */
+	uint64_t version; /* version of the code */
+	uint64_t hash_test; /* result of hashing HASH_MAGIC. */
+	uint64_t hash_seed; /* "random" seed written at creation time. */
+	ntdb_off_t free_table; /* (First) free table. */
+	ntdb_off_t recovery; /* Transaction recovery area. */
+
+	uint64_t features_used; /* Features all writers understand */
+	uint64_t features_offered; /* Features offered */
+
+	uint64_t seqnum; /* Sequence number for NTDB_SEQNUM */
+
+	ntdb_off_t capabilities; /* Optional linked list of capabilities. */
+	ntdb_off_t reserved[22];
+
+	/* Top level hash table. */
+	ntdb_off_t hashtable[1ULL << NTDB_TOPLEVEL_HASH_BITS];
+};
+
+struct ntdb_freetable {
+	struct ntdb_used_record hdr;
+	ntdb_off_t next;
+	ntdb_off_t buckets[NTDB_FREE_BUCKETS];
+};
+
+struct ntdb_capability {
+	struct ntdb_used_record hdr;
+	ntdb_off_t type;
+	ntdb_off_t next;
+	/* ... */
+};
+
+/* Information about a particular (locked) hash entry. */
+struct hash_info {
+	/* Full hash value of entry. */
+	uint64_t h;
+	/* Start and length of lock acquired. */
+	ntdb_off_t hlock_start;
+	ntdb_len_t hlock_range;
+	/* Start of hash group. */
+	ntdb_off_t group_start;
+	/* Bucket we belong in. */
+	unsigned int home_bucket;
+	/* Bucket we (or an empty space) were found in. */
+	unsigned int found_bucket;
+	/* How many bits of the hash are already used. */
+	unsigned int hash_used;
+	/* Current working group. */
+	ntdb_off_t group[1 << NTDB_HASH_GROUP_BITS];
+};
+
+struct traverse_info {
+	struct traverse_level {
+		ntdb_off_t hashtable;
+		/* We ignore groups here, and treat it as a big array. */
+		unsigned entry;
+		unsigned int total_buckets;
+	} levels[NTDB_MAX_LEVELS + 1];
+	unsigned int num_levels;
+	unsigned int toplevel_group;
+	/* This makes delete-everything-inside-traverse work as expected. */
+	ntdb_off_t prev;
+};
+
+enum ntdb_lock_flags {
+	/* WAIT == F_SETLKW, NOWAIT == F_SETLK */
+	NTDB_LOCK_NOWAIT = 0,
+	NTDB_LOCK_WAIT = 1,
+	/* If set, don't log an error on failure. */
+	NTDB_LOCK_PROBE = 2,
+	/* If set, don't check for recovery (used by recovery code). */
+	NTDB_LOCK_NOCHECK = 4,
+};
+
+struct ntdb_lock {
+	struct ntdb_context *owner;
+	off_t off;
+	uint32_t count;
+	uint32_t ltype;
+};
+
+/* This is only needed for ntdb_access_commit, but used everywhere to
+ * simplify. */
+struct ntdb_access_hdr {
+	struct ntdb_access_hdr *next;
+	ntdb_off_t off;
+	ntdb_len_t len;
+	bool convert;
+};
+
+struct ntdb_file {
+	/* How many are sharing us? */
+	unsigned int refcnt;
+
+	/* Mmap (if any), or malloc (for NTDB_INTERNAL). */
+	void *map_ptr;
+
+	/* How much space has been mapped (<= current file size) */
+	ntdb_len_t map_size;
+
+	/* The file descriptor (-1 for NTDB_INTERNAL). */
+	int fd;
+
+	/* Lock information */
+	pid_t locker;
+	struct ntdb_lock allrecord_lock;
+	size_t num_lockrecs;
+	struct ntdb_lock *lockrecs;
+
+	/* Identity of this file. */
+	dev_t device;
+	ino_t inode;
+};
+
+struct ntdb_methods {
+	enum NTDB_ERROR (*tread)(struct ntdb_context *, ntdb_off_t, void *,
+				 ntdb_len_t);
+	enum NTDB_ERROR (*twrite)(struct ntdb_context *, ntdb_off_t, const void *,
+				  ntdb_len_t);
+	enum NTDB_ERROR (*oob)(struct ntdb_context *, ntdb_off_t, ntdb_len_t, bool);
+	enum NTDB_ERROR (*expand_file)(struct ntdb_context *, ntdb_len_t);
+	void *(*direct)(struct ntdb_context *, ntdb_off_t, size_t, bool);
+};
+
+/*
+  internal prototypes
+*/
+/* hash.c: */
+uint64_t ntdb_jenkins_hash(const void *key, size_t length, uint64_t seed,
+			   void *unused);
+
+enum NTDB_ERROR first_in_hash(struct ntdb_context *ntdb,
+			      struct traverse_info *tinfo,
+			      NTDB_DATA *kbuf, size_t *dlen);
+
+enum NTDB_ERROR next_in_hash(struct ntdb_context *ntdb,
+			     struct traverse_info *tinfo,
+			     NTDB_DATA *kbuf, size_t *dlen);
+
+/* Hash random memory. */
+uint64_t ntdb_hash(struct ntdb_context *ntdb, const void *ptr, size_t len);
+
+/* Hash on disk. */
+uint64_t hash_record(struct ntdb_context *ntdb, ntdb_off_t off);
+
+/* Find and lock a hash entry (or where it would be). */
+ntdb_off_t find_and_lock(struct ntdb_context *ntdb,
+			 NTDB_DATA key,
+			 int ltype,
+			 struct hash_info *h,
+			 struct ntdb_used_record *rec,
+			 struct traverse_info *tinfo);
+
+enum NTDB_ERROR replace_in_hash(struct ntdb_context *ntdb,
+				struct hash_info *h,
+				ntdb_off_t new_off);
+
+enum NTDB_ERROR add_to_hash(struct ntdb_context *ntdb, struct hash_info *h,
+			    ntdb_off_t new_off);
+
+enum NTDB_ERROR delete_from_hash(struct ntdb_context *ntdb, struct hash_info *h);
+
+/* For ntdb_check */
+bool is_subhash(ntdb_off_t val);
+enum NTDB_ERROR unknown_capability(struct ntdb_context *ntdb, const char *caller,
+				   ntdb_off_t type);
+
+/* free.c: */
+enum NTDB_ERROR ntdb_ftable_init(struct ntdb_context *ntdb);
+
+/* check.c needs these to iterate through free lists. */
+ntdb_off_t first_ftable(struct ntdb_context *ntdb);
+ntdb_off_t next_ftable(struct ntdb_context *ntdb, ntdb_off_t ftable);
+
+/* This returns space or -ve error number. */
+ntdb_off_t alloc(struct ntdb_context *ntdb, size_t keylen, size_t datalen,
+		 uint64_t hash, unsigned magic, bool growing);
+
+/* Put this record in a free list. */
+enum NTDB_ERROR add_free_record(struct ntdb_context *ntdb,
+				ntdb_off_t off, ntdb_len_t len_with_header,
+				enum ntdb_lock_flags waitflag,
+				bool coalesce_ok);
+
+/* Set up header for a used/ftable/htable/chain/capability record. */
+enum NTDB_ERROR set_header(struct ntdb_context *ntdb,
+			   struct ntdb_used_record *rec,
+			   unsigned magic, uint64_t keylen, uint64_t datalen,
+			   uint64_t actuallen, unsigned hashlow);
+
+/* Used by ntdb_check to verify. */
+unsigned int size_to_bucket(ntdb_len_t data_len);
+ntdb_off_t bucket_off(ntdb_off_t ftable_off, unsigned bucket);
+
+/* Used by ntdb_summary */
+ntdb_off_t dead_space(struct ntdb_context *ntdb, ntdb_off_t off);
+
+/* Adjust expansion, used by create_recovery_area */
+ntdb_off_t ntdb_expand_adjust(ntdb_off_t map_size, ntdb_off_t size);
+
+/* io.c: */
+/* Initialize ntdb->methods. */
+void ntdb_io_init(struct ntdb_context *ntdb);
+
+/* Convert endian of the buffer if required. */
+void *ntdb_convert(const struct ntdb_context *ntdb, void *buf, ntdb_len_t size);
+
+/* Unmap and try to map the ntdb. */
+void ntdb_munmap(struct ntdb_file *file);
+enum NTDB_ERROR ntdb_mmap(struct ntdb_context *ntdb);
+
+/* Either alloc a copy, or give direct access.  Release frees or noop. */
+const void *ntdb_access_read(struct ntdb_context *ntdb,
+			     ntdb_off_t off, ntdb_len_t len, bool convert);
+void *ntdb_access_write(struct ntdb_context *ntdb,
+			ntdb_off_t off, ntdb_len_t len, bool convert);
+
+/* Release result of ntdb_access_read/write. */
+void ntdb_access_release(struct ntdb_context *ntdb, const void *p);
+/* Commit result of ntdb_acces_write. */
+enum NTDB_ERROR ntdb_access_commit(struct ntdb_context *ntdb, void *p);
+
+/* Convenience routine to get an offset. */
+ntdb_off_t ntdb_read_off(struct ntdb_context *ntdb, ntdb_off_t off);
+
+/* Write an offset at an offset. */
+enum NTDB_ERROR ntdb_write_off(struct ntdb_context *ntdb, ntdb_off_t off,
+			       ntdb_off_t val);
+
+/* Clear an ondisk area. */
+enum NTDB_ERROR zero_out(struct ntdb_context *ntdb, ntdb_off_t off, ntdb_len_t len);
+
+/* Return a non-zero offset between >= start < end in this array (or end). */
+ntdb_off_t ntdb_find_nonzero_off(struct ntdb_context *ntdb,
+				 ntdb_off_t base,
+				 uint64_t start,
+				 uint64_t end);
+
+/* Return a zero offset in this array, or num. */
+ntdb_off_t ntdb_find_zero_off(struct ntdb_context *ntdb, ntdb_off_t off,
+			      uint64_t num);
+
+/* Allocate and make a copy of some offset. */
+void *ntdb_alloc_read(struct ntdb_context *ntdb, ntdb_off_t offset, ntdb_len_t len);
+
+/* Writes a converted copy of a record. */
+enum NTDB_ERROR ntdb_write_convert(struct ntdb_context *ntdb, ntdb_off_t off,
+				   const void *rec, size_t len);
+
+/* Reads record and converts it */
+enum NTDB_ERROR ntdb_read_convert(struct ntdb_context *ntdb, ntdb_off_t off,
+				  void *rec, size_t len);
+
+/* Bump the seqnum (caller checks for ntdb->flags & NTDB_SEQNUM) */
+void ntdb_inc_seqnum(struct ntdb_context *ntdb);
+
+/* lock.c: */
+/* Print message because another ntdb owns a lock we want. */
+enum NTDB_ERROR owner_conflict(struct ntdb_context *ntdb, const char *call);
+
+/* If we fork, we no longer really own locks. */
+bool check_lock_pid(struct ntdb_context *ntdb, const char *call, bool log);
+
+/* Lock/unlock a range of hashes. */
+enum NTDB_ERROR ntdb_lock_hashes(struct ntdb_context *ntdb,
+				 ntdb_off_t hash_lock, ntdb_len_t hash_range,
+				 int ltype, enum ntdb_lock_flags waitflag);
+enum NTDB_ERROR ntdb_unlock_hashes(struct ntdb_context *ntdb,
+				   ntdb_off_t hash_lock,
+				   ntdb_len_t hash_range, int ltype);
+
+/* For closing the file. */
+void ntdb_lock_cleanup(struct ntdb_context *ntdb);
+
+/* Lock/unlock a particular free bucket. */
+enum NTDB_ERROR ntdb_lock_free_bucket(struct ntdb_context *ntdb, ntdb_off_t b_off,
+				      enum ntdb_lock_flags waitflag);
+void ntdb_unlock_free_bucket(struct ntdb_context *ntdb, ntdb_off_t b_off);
+
+/* Serialize transaction start. */
+enum NTDB_ERROR ntdb_transaction_lock(struct ntdb_context *ntdb, int ltype);
+void ntdb_transaction_unlock(struct ntdb_context *ntdb, int ltype);
+
+/* Do we have any hash locks (ie. via ntdb_chainlock) ? */
+bool ntdb_has_hash_locks(struct ntdb_context *ntdb);
+
+/* Lock entire database. */
+enum NTDB_ERROR ntdb_allrecord_lock(struct ntdb_context *ntdb, int ltype,
+				    enum ntdb_lock_flags flags, bool upgradable);
+void ntdb_allrecord_unlock(struct ntdb_context *ntdb, int ltype);
+enum NTDB_ERROR ntdb_allrecord_upgrade(struct ntdb_context *ntdb, off_t start);
+
+/* Serialize db open. */
+enum NTDB_ERROR ntdb_lock_open(struct ntdb_context *ntdb,
+			       int ltype, enum ntdb_lock_flags flags);
+void ntdb_unlock_open(struct ntdb_context *ntdb, int ltype);
+bool ntdb_has_open_lock(struct ntdb_context *ntdb);
+
+/* Serialize db expand. */
+enum NTDB_ERROR ntdb_lock_expand(struct ntdb_context *ntdb, int ltype);
+void ntdb_unlock_expand(struct ntdb_context *ntdb, int ltype);
+bool ntdb_has_expansion_lock(struct ntdb_context *ntdb);
+
+/* If it needs recovery, grab all the locks and do it. */
+enum NTDB_ERROR ntdb_lock_and_recover(struct ntdb_context *ntdb);
+
+/* Default lock and unlock functions. */
+int ntdb_fcntl_lock(int fd, int rw, off_t off, off_t len, bool waitflag, void *);
+int ntdb_fcntl_unlock(int fd, int rw, off_t off, off_t len, void *);
+
+/* transaction.c: */
+enum NTDB_ERROR ntdb_transaction_recover(struct ntdb_context *ntdb);
+ntdb_bool_err ntdb_needs_recovery(struct ntdb_context *ntdb);
+
+struct ntdb_context {
+	/* Single list of all TDBs, to detect multiple opens. */
+	struct ntdb_context *next;
+
+	/* Filename of the database. */
+	const char *name;
+
+	/* Logging function */
+	void (*log_fn)(struct ntdb_context *ntdb,
+		       enum ntdb_log_level level,
+		       enum NTDB_ERROR ecode,
+		       const char *message,
+		       void *data);
+	void *log_data;
+
+	/* Open flags passed to ntdb_open. */
+	int open_flags;
+
+	/* low level (fnctl) lock functions. */
+	int (*lock_fn)(int fd, int rw, off_t off, off_t len, bool w, void *);
+	int (*unlock_fn)(int fd, int rw, off_t off, off_t len, void *);
+	void *lock_data;
+
+	/* the ntdb flags passed to ntdb_open. */
+	uint32_t flags;
+
+	/* Our statistics. */
+	struct ntdb_attribute_stats stats;
+
+	/* The actual file information */
+	struct ntdb_file *file;
+
+	/* Hash function. */
+	uint64_t (*hash_fn)(const void *key, size_t len, uint64_t seed, void *);
+	void *hash_data;
+	uint64_t hash_seed;
+
+	/* Our open hook, if any. */
+	enum NTDB_ERROR (*openhook)(int fd, void *data);
+	void *openhook_data;
+
+	/* Last error we returned. */
+	enum NTDB_ERROR last_error;
+
+	/* Are we accessing directly? (debugging check). */
+	int direct_access;
+
+	/* Set if we are in a transaction. */
+	struct ntdb_transaction *transaction;
+
+	/* What free table are we using? */
+	ntdb_off_t ftable_off;
+	unsigned int ftable;
+
+	/* IO methods: changes for transactions. */
+	const struct ntdb_methods *io;
+
+	/* Direct access information */
+	struct ntdb_access_hdr *access;
+};
+
+/* ntdb.c: */
+enum NTDB_ERROR COLD PRINTF_FMT(4, 5)
+	ntdb_logerr(struct ntdb_context *ntdb,
+		    enum NTDB_ERROR ecode,
+		    enum ntdb_log_level level,
+		    const char *fmt, ...);
+
+#ifdef NTDB_TRACE
+void ntdb_trace(struct ntdb_context *ntdb, const char *op);
+void ntdb_trace_seqnum(struct ntdb_context *ntdb, uint32_t seqnum, const char *op);
+void ntdb_trace_open(struct ntdb_context *ntdb, const char *op,
+		     unsigned hash_size, unsigned ntdb_flags, unsigned open_flags);
+void ntdb_trace_ret(struct ntdb_context *ntdb, const char *op, int ret);
+void ntdb_trace_retrec(struct ntdb_context *ntdb, const char *op, NTDB_DATA ret);
+void ntdb_trace_1rec(struct ntdb_context *ntdb, const char *op,
+		     NTDB_DATA rec);
+void ntdb_trace_1rec_ret(struct ntdb_context *ntdb, const char *op,
+			 NTDB_DATA rec, int ret);
+void ntdb_trace_1rec_retrec(struct ntdb_context *ntdb, const char *op,
+			    NTDB_DATA rec, NTDB_DATA ret);
+void ntdb_trace_2rec_flag_ret(struct ntdb_context *ntdb, const char *op,
+			      NTDB_DATA rec1, NTDB_DATA rec2, unsigned flag,
+			      int ret);
+void ntdb_trace_2rec_retrec(struct ntdb_context *ntdb, const char *op,
+			    NTDB_DATA rec1, NTDB_DATA rec2, NTDB_DATA ret);
+#else
+#define ntdb_trace(ntdb, op)
+#define ntdb_trace_seqnum(ntdb, seqnum, op)
+#define ntdb_trace_open(ntdb, op, hash_size, ntdb_flags, open_flags)
+#define ntdb_trace_ret(ntdb, op, ret)
+#define ntdb_trace_retrec(ntdb, op, ret)
+#define ntdb_trace_1rec(ntdb, op, rec)
+#define ntdb_trace_1rec_ret(ntdb, op, rec, ret)
+#define ntdb_trace_1rec_retrec(ntdb, op, rec, ret)
+#define ntdb_trace_2rec_flag_ret(ntdb, op, rec1, rec2, flag, ret)
+#define ntdb_trace_2rec_retrec(ntdb, op, rec1, rec2, ret)
+#endif /* !NTDB_TRACE */
+
+#endif