X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb2%2Ftdb1_open.c;h=1fe981ac76b2a7f688ad6c4c70f534235f4e3001;hp=7c5100e3d1e17c45aed7edc51f76f537e2018106;hb=fbad02b680b6cbc33ae305ae1cbcdead4eedc7b1;hpb=39f55294799c6443c0ad7bef09f1c113cf89d295

diff --git a/ccan/tdb2/tdb1_open.c b/ccan/tdb2/tdb1_open.c
index 7c5100e3..1fe981ac 100644
--- a/ccan/tdb2/tdb1_open.c
+++ b/ccan/tdb2/tdb1_open.c
@@ -34,11 +34,11 @@ static struct tdb1_context *tdb1s = NULL;
 void tdb1_header_hash(struct tdb1_context *tdb,
 		     uint32_t *magic1_hash, uint32_t *magic2_hash)
 {
-	TDB1_DATA hash_key;
+	TDB_DATA hash_key;
 	uint32_t tdb1_magic = TDB1_MAGIC;
 
-	hash_key.dptr = (unsigned char *)TDB1_MAGIC_FOOD;
-	hash_key.dsize = sizeof(TDB1_MAGIC_FOOD);
+	hash_key.dptr = (unsigned char *)TDB_MAGIC_FOOD;
+	hash_key.dsize = sizeof(TDB_MAGIC_FOOD);
 	*magic1_hash = tdb->hash_fn(&hash_key);
 
 	hash_key.dptr = (unsigned char *)TDB1_CONV(tdb1_magic);
@@ -60,7 +60,7 @@ static int tdb1_new_database(struct tdb1_context *tdb, int hash_size)
 	/* We make it up in memory, then write it out if not internal */
 	size = sizeof(struct tdb1_header) + (hash_size+1)*sizeof(tdb1_off_t);
 	if (!(newdb = (struct tdb1_header *)calloc(size, 1))) {
-		tdb->ecode = TDB1_ERR_OOM;
+		tdb->last_error = TDB_ERR_OOM;
 		return -1;
 	}
 
@@ -72,30 +72,31 @@ static int tdb1_new_database(struct tdb1_context *tdb, int hash_size)
 
 	/* Make sure older tdbs (which don't check the magic hash fields)
 	 * will refuse to open this TDB. */
-	if (tdb->flags & TDB1_INCOMPATIBLE_HASH)
+	if (tdb->hash_fn == tdb1_incompatible_hash)
 		newdb->rwlocks = TDB1_HASH_RWLOCK_MAGIC;
 
-	if (tdb->flags & TDB1_INTERNAL) {
-		tdb->map_size = size;
-		tdb->map_ptr = (char *)newdb;
+	if (tdb->flags & TDB_INTERNAL) {
+		tdb->file->fd = -1;
+		tdb->file->map_size = size;
+		tdb->file->map_ptr = (char *)newdb;
 		memcpy(&tdb->header, newdb, sizeof(tdb->header));
 		/* Convert the `ondisk' version if asked. */
 		TDB1_CONV(*newdb);
 		return 0;
 	}
-	if (lseek(tdb->fd, 0, SEEK_SET) == -1)
+	if (lseek(tdb->file->fd, 0, SEEK_SET) == -1)
 		goto fail;
 
-	if (ftruncate(tdb->fd, 0) == -1)
+	if (ftruncate(tdb->file->fd, 0) == -1)
 		goto fail;
 
 	/* This creates an endian-converted header, as if read from disk */
 	TDB1_CONV(*newdb);
 	memcpy(&tdb->header, newdb, sizeof(tdb->header));
 	/* Don't endian-convert the magic food! */
-	memcpy(newdb->magic_food, TDB1_MAGIC_FOOD, strlen(TDB1_MAGIC_FOOD)+1);
+	memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1);
 	/* we still have "ret == -1" here */
-	if (tdb1_write_all(tdb->fd, newdb, size))
+	if (tdb1_write_all(tdb->file->fd, newdb, size))
 		ret = 0;
 
   fail:
@@ -111,7 +112,7 @@ static int tdb1_already_open(dev_t device,
 	struct tdb1_context *i;
 
 	for (i = tdb1s; i; i = i->next) {
-		if (i->device == device && i->inode == ino) {
+		if (i->file->device == device && i->file->inode == ino) {
 			return 1;
 		}
 	}
@@ -135,31 +136,28 @@ struct tdb1_context *tdb1_open(const char *name, int hash_size, int tdb1_flags,
 	return tdb1_open_ex(name, hash_size, tdb1_flags, open_flags, mode, NULL, NULL);
 }
 
-/* a default logging function */
-static void null_log_fn(struct tdb1_context *tdb, enum tdb1_debug_level level, const char *fmt, ...) PRINTF_ATTRIBUTE(3, 4);
-static void null_log_fn(struct tdb1_context *tdb, enum tdb1_debug_level level, const char *fmt, ...)
+static bool hash_correct(struct tdb1_context *tdb,
+			 uint32_t *m1, uint32_t *m2)
 {
+	tdb1_header_hash(tdb, m1, m2);
+	return (tdb->header.magic1_hash == *m1 &&
+		tdb->header.magic2_hash == *m2);
 }
 
 static bool check_header_hash(struct tdb1_context *tdb,
-			      bool default_hash, uint32_t *m1, uint32_t *m2)
+			      uint32_t *m1, uint32_t *m2)
 {
-	tdb1_header_hash(tdb, m1, m2);
-	if (tdb->header.magic1_hash == *m1 &&
-	    tdb->header.magic2_hash == *m2) {
+	if (hash_correct(tdb, m1, m2))
 		return true;
-	}
-
-	/* If they explicitly set a hash, always respect it. */
-	if (!default_hash)
-		return false;
 
-	/* Otherwise, try the other inbuilt hash. */
+	/* If they use one inbuilt, try the other inbuilt hash. */
 	if (tdb->hash_fn == tdb1_old_hash)
-		tdb->hash_fn = tdb1_jenkins_hash;
-	else
+		tdb->hash_fn = tdb1_incompatible_hash;
+	else if (tdb->hash_fn == tdb1_incompatible_hash)
 		tdb->hash_fn = tdb1_old_hash;
-	return check_header_hash(tdb, false, m1, m2);
+	else
+		return false;
+	return hash_correct(tdb, m1, m2);
 }
 
 struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flags,
@@ -169,9 +167,7 @@ struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flag
 {
 	struct tdb1_context *tdb;
 	struct stat st;
-	int rev = 0, locked = 0;
-	unsigned char *vp;
-	uint32_t vertest;
+	int rev = 0;
 	unsigned v;
 	const char *hash_alg;
 	uint32_t magic1, magic2;
@@ -181,26 +177,34 @@ struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flag
 		errno = ENOMEM;
 		goto fail;
 	}
+	tdb->file = calloc(1, sizeof *tdb->file);
+	if (!tdb->file) {
+		free(tdb);
+		errno = ENOMEM;
+		goto fail;
+	}
 	tdb1_io_init(tdb);
-	tdb->fd = -1;
+	tdb->file->fd = -1;
 	tdb->name = NULL;
-	tdb->map_ptr = NULL;
-	tdb->flags = tdb1_flags;
+	tdb->file->map_ptr = NULL;
+	tdb->flags = tdb1_flags|TDB_VERSION1;
 	tdb->open_flags = open_flags;
+	tdb->lock_fn = tdb_fcntl_lock;
+	tdb->unlock_fn = tdb_fcntl_unlock;
 	if (log_ctx) {
-		tdb->log = *log_ctx;
-	} else {
-		tdb->log.log_fn = null_log_fn;
-		tdb->log.log_private = NULL;
-	}
+		tdb->log_fn = log_ctx->log_fn;
+		tdb->log_data = log_ctx->log_private;
+	} else
+		tdb->log_fn = NULL;
 
-	if (name == NULL && (tdb1_flags & TDB1_INTERNAL)) {
+	if (name == NULL && (tdb1_flags & TDB_INTERNAL)) {
 		name = "__TDB1_INTERNAL__";
 	}
 
 	if (name == NULL) {
 		tdb->name = (char *)"__NULL__";
-		TDB1_LOG((tdb, TDB1_DEBUG_FATAL, "tdb1_open_ex: called with name == NULL\n"));
+		tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
+			   "tdb1_open_ex: called with name == NULL");
 		tdb->name = NULL;
 		errno = EINVAL;
 		goto fail;
@@ -213,8 +217,8 @@ struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flag
 		 * work in case of an error.
 		 */
 		tdb->name = (char *)name;
-		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_open_ex: can't strdup(%s)\n",
-			 name));
+		tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
+			   "tdb1_open_ex: can't strdup(%s)", name);
 		tdb->name = NULL;
 		errno = ENOMEM;
 		goto fail;
@@ -222,15 +226,13 @@ struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flag
 
 	if (hash_fn) {
 		tdb->hash_fn = hash_fn;
-		hash_alg = "the user defined";
+		if (hash_fn == tdb1_incompatible_hash)
+			hash_alg = "tdb1_incompatible_hash";
+		else
+			hash_alg = "the user defined";
 	} else {
-		/* This controls what we use when creating a tdb. */
-		if (tdb->flags & TDB1_INCOMPATIBLE_HASH) {
-			tdb->hash_fn = tdb1_jenkins_hash;
-		} else {
-			tdb->hash_fn = tdb1_old_hash;
-		}
-		hash_alg = "either default";
+		tdb->hash_fn = tdb1_old_hash;
+		hash_alg = "default";
 	}
 
 	/* cache the page size */
@@ -239,11 +241,13 @@ struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flag
 		tdb->page_size = 0x2000;
 	}
 
-	tdb->max_dead_records = (tdb1_flags & TDB1_VOLATILE) ? 5 : 0;
+	/* FIXME: Used to be 5 for TDB_VOLATILE. */
+	tdb->max_dead_records = 0;
 
 	if ((open_flags & O_ACCMODE) == O_WRONLY) {
-		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_open_ex: can't open tdb %s write-only\n",
-			 name));
+		tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
+			   "tdb1_open_ex: can't open tdb %s write-only",
+			   name);
 		errno = EINVAL;
 		goto fail;
 	}
@@ -252,160 +256,106 @@ struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flag
 		hash_size = TDB1_DEFAULT_HASH_SIZE;
 	if ((open_flags & O_ACCMODE) == O_RDONLY) {
 		tdb->read_only = 1;
-		/* read only databases don't do locking or clear if first */
-		tdb->flags |= TDB1_NOLOCK;
-		tdb->flags &= ~TDB1_CLEAR_IF_FIRST;
-	}
-
-	if ((tdb->flags & TDB1_ALLOW_NESTING) &&
-	    (tdb->flags & TDB1_DISALLOW_NESTING)) {
-		tdb->ecode = TDB1_ERR_NESTING;
-		TDB1_LOG((tdb, TDB1_DEBUG_FATAL, "tdb1_open_ex: "
-			"allow_nesting and disallow_nesting are not allowed together!"));
-		errno = EINVAL;
-		goto fail;
-	}
-
-	if (getenv("TDB_NO_FSYNC")) {
-		tdb->flags |= TDB1_NOSYNC;
-	}
-
-	/*
-	 * TDB1_ALLOW_NESTING is the default behavior.
-	 * Note: this may change in future versions!
-	 */
-	if (!(tdb->flags & TDB1_DISALLOW_NESTING)) {
-		tdb->flags |= TDB1_ALLOW_NESTING;
+		/* read only databases don't do locking */
+		tdb->flags |= TDB_NOLOCK;
 	}
 
 	/* internal databases don't mmap or lock, and start off cleared */
-	if (tdb->flags & TDB1_INTERNAL) {
-		tdb->flags |= (TDB1_NOLOCK | TDB1_NOMMAP);
-		tdb->flags &= ~TDB1_CLEAR_IF_FIRST;
+	if (tdb->flags & TDB_INTERNAL) {
+		tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 		if (tdb1_new_database(tdb, hash_size) != 0) {
-			TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_open_ex: tdb1_new_database failed!"));
+			tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
+				   "tdb1_open_ex: tdb1_new_database failed!");
 			goto fail;
 		}
 		goto internal;
 	}
 
-	if ((tdb->fd = open(name, open_flags, mode)) == -1) {
-		TDB1_LOG((tdb, TDB1_DEBUG_WARNING, "tdb1_open_ex: could not open file %s: %s\n",
-			 name, strerror(errno)));
+	if ((tdb->file->fd = open(name, open_flags, mode)) == -1) {
+		tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+			   "tdb1_open_ex: could not open file %s: %s",
+			   name, strerror(errno));
 		goto fail;	/* errno set by open(2) */
 	}
 
 	/* on exec, don't inherit the fd */
-	v = fcntl(tdb->fd, F_GETFD, 0);
-        fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
+	v = fcntl(tdb->file->fd, F_GETFD, 0);
+        fcntl(tdb->file->fd, F_SETFD, v | FD_CLOEXEC);
 
 	/* ensure there is only one process initialising at once */
-	if (tdb1_nest_lock(tdb, TDB1_OPEN_LOCK, F_WRLCK, TDB1_LOCK_WAIT) == -1) {
-		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_open_ex: failed to get open lock on %s: %s\n",
-			 name, strerror(errno)));
+	if (tdb1_nest_lock(tdb, TDB1_OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
+		tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
+			   "tdb1_open_ex: failed to get open lock on %s: %s",
+			   name, strerror(errno));
 		goto fail;	/* errno set by tdb1_brlock */
 	}
 
-	/* we need to zero database if we are the only one with it open */
-	if ((tdb1_flags & TDB1_CLEAR_IF_FIRST) &&
-	    (!tdb->read_only) &&
-	    (locked = (tdb1_nest_lock(tdb, TDB1_ACTIVE_LOCK, F_WRLCK, TDB1_LOCK_NOWAIT|TDB1_LOCK_PROBE) == 0))) {
-		open_flags |= O_CREAT;
-		if (ftruncate(tdb->fd, 0) == -1) {
-			TDB1_LOG((tdb, TDB1_DEBUG_FATAL, "tdb1_open_ex: "
-				 "failed to truncate %s: %s\n",
-				 name, strerror(errno)));
-			goto fail; /* errno set by ftruncate */
-		}
-	}
-
 	errno = 0;
-	if (read(tdb->fd, &tdb->header, sizeof(tdb->header)) != sizeof(tdb->header)
-	    || strcmp(tdb->header.magic_food, TDB1_MAGIC_FOOD) != 0) {
+	if (read(tdb->file->fd, &tdb->header, sizeof(tdb->header)) != sizeof(tdb->header)
+	    || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0) {
 		if (!(open_flags & O_CREAT) || tdb1_new_database(tdb, hash_size) == -1) {
 			if (errno == 0) {
 				errno = EIO; /* ie bad format or something */
 			}
 			goto fail;
 		}
-		rev = (tdb->flags & TDB1_CONVERT);
+		rev = (tdb->flags & TDB_CONVERT);
 	} else if (tdb->header.version != TDB1_VERSION
 		   && !(rev = (tdb->header.version==TDB1_BYTEREV(TDB1_VERSION)))) {
 		/* wrong version */
 		errno = EIO;
 		goto fail;
 	}
-	vp = (unsigned char *)&tdb->header.version;
-	vertest = (((uint32_t)vp[0]) << 24) | (((uint32_t)vp[1]) << 16) |
-		  (((uint32_t)vp[2]) << 8) | (uint32_t)vp[3];
-	tdb->flags |= (vertest==TDB1_VERSION) ? TDB1_BIGENDIAN : 0;
 	if (!rev)
-		tdb->flags &= ~TDB1_CONVERT;
+		tdb->flags &= ~TDB_CONVERT;
 	else {
-		tdb->flags |= TDB1_CONVERT;
+		tdb->flags |= TDB_CONVERT;
 		tdb1_convert(&tdb->header, sizeof(tdb->header));
 	}
-	if (fstat(tdb->fd, &st) == -1)
+	if (fstat(tdb->file->fd, &st) == -1)
 		goto fail;
 
 	if (tdb->header.rwlocks != 0 &&
 	    tdb->header.rwlocks != TDB1_HASH_RWLOCK_MAGIC) {
-		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_open_ex: spinlocks no longer supported\n"));
+		tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
+			   "tdb1_open_ex: spinlocks no longer supported");
 		goto fail;
 	}
 
 	if ((tdb->header.magic1_hash == 0) && (tdb->header.magic2_hash == 0)) {
 		/* older TDB without magic hash references */
 		tdb->hash_fn = tdb1_old_hash;
-	} else if (!check_header_hash(tdb, !hash_fn, &magic1, &magic2)) {
-		TDB1_LOG((tdb, TDB1_DEBUG_FATAL, "tdb1_open_ex: "
-			 "%s was not created with %s hash function we are using\n"
-			 "magic1_hash[0x%08X %s 0x%08X] "
-			 "magic2_hash[0x%08X %s 0x%08X]\n",
-			 name, hash_alg,
-			 tdb->header.magic1_hash,
-			 (tdb->header.magic1_hash == magic1) ? "==" : "!=",
-			 magic1,
-			 tdb->header.magic2_hash,
-			 (tdb->header.magic2_hash == magic2) ? "==" : "!=",
-			 magic2));
+	} else if (!check_header_hash(tdb, &magic1, &magic2)) {
+		tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_USE_ERROR,
+			   "tdb1_open_ex: "
+			   "%s was not created with %s hash function we are using\n"
+			   "magic1_hash[0x%08X %s 0x%08X] "
+			   "magic2_hash[0x%08X %s 0x%08X]",
+			   name, hash_alg,
+			   tdb->header.magic1_hash,
+			   (tdb->header.magic1_hash == magic1) ? "==" : "!=",
+			   magic1,
+			   tdb->header.magic2_hash,
+			   (tdb->header.magic2_hash == magic2) ? "==" : "!=",
+			   magic2);
 		errno = EINVAL;
 		goto fail;
 	}
 
 	/* Is it already in the open list?  If so, fail. */
 	if (tdb1_already_open(st.st_dev, st.st_ino)) {
-		TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_open_ex: "
-			 "%s (%d,%d) is already open in this process\n",
-			 name, (int)st.st_dev, (int)st.st_ino));
+		tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_USE_ERROR,
+			   "tdb1_open_ex: "
+			   "%s (%d,%d) is already open in this process",
+			   name, (int)st.st_dev, (int)st.st_ino);
 		errno = EBUSY;
 		goto fail;
 	}
 
-	tdb->map_size = st.st_size;
-	tdb->device = st.st_dev;
-	tdb->inode = st.st_ino;
+	tdb->file->map_size = st.st_size;
+	tdb->file->device = st.st_dev;
+	tdb->file->inode = st.st_ino;
 	tdb1_mmap(tdb);
-	if (locked) {
-		if (tdb1_nest_unlock(tdb, TDB1_ACTIVE_LOCK, F_WRLCK, false) == -1) {
-			TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_open_ex: "
-				 "failed to release ACTIVE_LOCK on %s: %s\n",
-				 name, strerror(errno)));
-			goto fail;
-		}
-
-	}
-
-	/* We always need to do this if the CLEAR_IF_FIRST flag is set, even if
-	   we didn't get the initial exclusive lock as we need to let all other
-	   users know we're using it. */
-
-	if (tdb1_flags & TDB1_CLEAR_IF_FIRST) {
-		/* leave this lock in place to indicate it's in use */
-		if (tdb1_nest_lock(tdb, TDB1_ACTIVE_LOCK, F_RDLCK, TDB1_LOCK_WAIT) == -1) {
-			goto fail;
-		}
-	}
 
 	/* if needed, run recovery */
 	if (tdb1_transaction_recover(tdb) == -1) {
@@ -416,7 +366,7 @@ struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flag
 	/* Internal (memory-only) databases skip all the code above to
 	 * do with disk files, and resume here by releasing their
 	 * open lock and hooking into the active list. */
-	if (tdb1_nest_unlock(tdb, TDB1_OPEN_LOCK, F_WRLCK, false) == -1) {
+	if (tdb1_nest_unlock(tdb, TDB1_OPEN_LOCK, F_WRLCK) == -1) {
 		goto fail;
 	}
 	tdb->next = tdb1s;
@@ -429,16 +379,20 @@ struct tdb1_context *tdb1_open_ex(const char *name, int hash_size, int tdb1_flag
 	if (!tdb)
 		return NULL;
 
-	if (tdb->map_ptr) {
-		if (tdb->flags & TDB1_INTERNAL)
-			SAFE_FREE(tdb->map_ptr);
+	if (tdb->file->map_ptr) {
+		if (tdb->flags & TDB_INTERNAL)
+			SAFE_FREE(tdb->file->map_ptr);
 		else
 			tdb1_munmap(tdb);
 	}
-	if (tdb->fd != -1)
-		if (close(tdb->fd) != 0)
-			TDB1_LOG((tdb, TDB1_DEBUG_ERROR, "tdb1_open_ex: failed to close tdb->fd on error!\n"));
-	SAFE_FREE(tdb->lockrecs);
+	if (tdb->file->fd != -1)
+		if (close(tdb->file->fd) != 0)
+			tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+				   "tdb1_open_ex: failed to close tdb->fd on error!");
+	if (tdb->file) {
+		SAFE_FREE(tdb->file->lockrecs);
+		SAFE_FREE(tdb->file);
+	}
 	SAFE_FREE(tdb->name);
 	SAFE_FREE(tdb);
 	errno = save_errno;
@@ -469,18 +423,19 @@ int tdb1_close(struct tdb1_context *tdb)
 		tdb1_transaction_cancel(tdb);
 	}
 
-	if (tdb->map_ptr) {
-		if (tdb->flags & TDB1_INTERNAL)
-			SAFE_FREE(tdb->map_ptr);
+	if (tdb->file->map_ptr) {
+		if (tdb->flags & TDB_INTERNAL)
+			SAFE_FREE(tdb->file->map_ptr);
 		else
 			tdb1_munmap(tdb);
 	}
 	SAFE_FREE(tdb->name);
-	if (tdb->fd != -1) {
-		ret = close(tdb->fd);
-		tdb->fd = -1;
+	if (tdb->file->fd != -1) {
+		ret = close(tdb->file->fd);
+		tdb->file->fd = -1;
 	}
-	SAFE_FREE(tdb->lockrecs);
+	SAFE_FREE(tdb->file->lockrecs);
+	SAFE_FREE(tdb->file);
 
 	/* Remove from contexts list */
 	for (i = &tdb1s; *i; i = &(*i)->next) {