r22775: For the cluster code I've developed a wrapper around tdb to put different

database backends in place dynamically.

The main abstractions are db_context and db_record, it should be mainly
self-describing, see include/dbwrap.h.  You open the db just as you would open
a tdb, this time with db_open(). If you want to fetch a record, just do the
db->fetch() call, if you want to do operations on it, you need to get it with
fetch_locked().

I added dbwrap_file.c (not heavily tested lately) as an example for what can
be done with that abstraction, uses a file per key. So if anybody is willing
to shape that up, we might have a chance on reiserfs again.... :-)

This abstraction works fine for brlock.tdb, locking.tdb, connections.tdb and
sessionid.tdb. It should work fine for the others as well, I just did not yet
get around to convert them.

If nobody loudly screams NO, then I will import the code that uses this soon.

Volker
(This used to be commit e9d7484ca246cfca4a1fd23be35edc2783136ebe)

1 files changed, 227 insertions, 0 deletions

diff --git a/source3/lib/dbwrap_tdb.c b/source3/lib/dbwrap_tdb.c
new file mode 100644
index 0000000000..238ba51761
--- /dev/null
+++ b/source3/lib/dbwrap_tdb.c
@@ -0,0 +1,227 @@
+/* 
+   Unix SMB/CIFS implementation.
+   Database interface wrapper around tdb
+   Copyright (C) Volker Lendecke 2005-2007
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program 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 General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "includes.h"
+
+struct db_tdb_ctx {
+	TDB_CONTEXT *tdb;
+};
+
+static NTSTATUS db_tdb_store(struct db_record *rec, TDB_DATA data, int flag);
+static NTSTATUS db_tdb_delete(struct db_record *rec);
+
+static int db_tdb_record_destr(struct db_record* data)
+{
+	struct db_tdb_ctx *ctx =
+		talloc_get_type_abort(data->private_data, struct db_tdb_ctx);
+
+	DEBUG(10, ("Unlocking key %s\n",
+		   hex_encode(data, (unsigned char *)data->key.dptr,
+			      data->key.dsize)));
+
+	if (tdb_chainunlock(ctx->tdb, data->key) != 0) {
+		DEBUG(0, ("tdb_chainunlock failed\n"));
+		return -1;
+	}
+	return 0;
+}
+
+static struct db_record *db_tdb_fetch_locked(struct db_context *db,
+				     TALLOC_CTX *mem_ctx, TDB_DATA key)
+{
+	struct db_tdb_ctx *ctx = talloc_get_type_abort(db->private_data,
+						       struct db_tdb_ctx);
+	struct db_record *result;
+	TDB_DATA value;
+
+	result = TALLOC_P(mem_ctx, struct db_record);
+	if (result == NULL) {
+		DEBUG(0, ("talloc failed\n"));
+		return NULL;
+	}
+
+	result->key.dsize = key.dsize;
+	result->key.dptr = (uint8 *)talloc_memdup(result, key.dptr, key.dsize);
+	if (result->key.dptr == NULL) {
+		DEBUG(0, ("talloc failed\n"));
+		TALLOC_FREE(result);
+		return NULL;
+	}
+
+	result->value.dptr = NULL;
+	result->value.dsize = 0;
+	result->private_data = talloc_reference(result, ctx);
+	result->store = db_tdb_store;
+	result->delete_rec = db_tdb_delete;
+
+	{
+		char *keystr = hex_encode(NULL, (unsigned char *)key.dptr,
+					  key.dsize);
+		DEBUG(10, ("Locking key %s\n", keystr));
+		TALLOC_FREE(keystr);
+	}
+
+	if (tdb_chainlock(ctx->tdb, key) != 0) {
+		DEBUG(3, ("tdb_chainlock failed\n"));
+		TALLOC_FREE(result);
+		return NULL;
+	}
+
+	talloc_set_destructor(result, db_tdb_record_destr);
+
+	value = tdb_fetch(ctx->tdb, key);
+
+	if (value.dptr == NULL) {
+		return result;
+	}
+
+	result->value.dsize = value.dsize;
+	result->value.dptr = (uint8 *)talloc_memdup(result, value.dptr,
+						    value.dsize);
+	if (result->value.dptr == NULL) {
+		DEBUG(3, ("talloc failed\n"));
+		TALLOC_FREE(result);
+		return NULL;
+	}
+
+	SAFE_FREE(value.dptr);
+
+	DEBUG(10, ("Allocated locked data 0x%p\n", result));
+
+	return result;
+}
+
+static NTSTATUS db_tdb_store(struct db_record *rec, TDB_DATA data, int flag)
+{
+	struct db_tdb_ctx *ctx = talloc_get_type_abort(rec->private_data,
+						       struct db_tdb_ctx);
+
+	/*
+	 * This has a bug: We need to replace rec->value for correct
+	 * operation, but right now brlock and locking don't use the value
+	 * anymore after it was stored.
+	 */
+
+	return (tdb_store(ctx->tdb, rec->key, data, flag) == 0) ?
+		NT_STATUS_OK : NT_STATUS_UNSUCCESSFUL;
+}
+
+static NTSTATUS db_tdb_delete(struct db_record *rec)
+{
+	struct db_tdb_ctx *ctx = talloc_get_type_abort(rec->private_data,
+						       struct db_tdb_ctx);
+
+	return (tdb_delete(ctx->tdb, rec->key) == 0) ?
+		NT_STATUS_OK : NT_STATUS_UNSUCCESSFUL;
+}
+
+struct db_tdb_traverse_ctx {
+	struct db_context *db;
+	int (*f)(struct db_record *rec, void *private_data);
+	void *private_data;
+};
+
+static int db_tdb_traverse_func(TDB_CONTEXT *tdb, TDB_DATA kbuf, TDB_DATA dbuf,
+				void *private_data)
+{
+	struct db_tdb_traverse_ctx *ctx =
+		(struct db_tdb_traverse_ctx *)private_data;
+	struct db_record rec;
+
+	rec.key = kbuf;
+	rec.value = dbuf;
+	rec.store = db_tdb_store;
+	rec.delete_rec = db_tdb_delete;
+	rec.private_data = ctx->db->private_data;
+
+	return ctx->f(&rec, ctx->private_data);
+}
+
+static int db_tdb_traverse(struct db_context *db,
+			   int (*f)(struct db_record *rec, void *private_data),
+			   void *private_data)
+{
+	struct db_tdb_ctx *db_ctx =
+		talloc_get_type_abort(db->private_data, struct db_tdb_ctx);
+	struct db_tdb_traverse_ctx ctx;
+
+	ctx.db = db;
+	ctx.f = f;
+	ctx.private_data = private_data;
+	return tdb_traverse(db_ctx->tdb, db_tdb_traverse_func, &ctx);
+}
+
+static int db_tdb_get_seqnum(struct db_context *db)
+
+{
+	struct db_tdb_ctx *db_ctx =
+		talloc_get_type_abort(db->private_data, struct db_tdb_ctx);
+	return tdb_get_seqnum(db_ctx->tdb);
+}
+
+static int db_tdb_ctx_destr(struct db_tdb_ctx *ctx)
+{
+	if (tdb_close(ctx->tdb) != 0) {
+		DEBUG(0, ("Failed to close tdb: %s\n", strerror(errno)));
+		return -1;
+	}
+
+	return 0;
+}
+
+struct db_context *db_open_tdb(TALLOC_CTX *mem_ctx,
+			       const char *name,
+			       int hash_size, int tdb_flags,
+			       int open_flags, mode_t mode)
+{
+	struct db_context *result = NULL;
+	struct db_tdb_ctx *db_tdb;
+
+	result = TALLOC_ZERO_P(mem_ctx, struct db_context);
+	if (result == NULL) {
+		DEBUG(0, ("talloc failed\n"));
+		goto fail;
+	}
+
+	result->private_data = db_tdb = TALLOC_P(result, struct db_tdb_ctx);
+	if (db_tdb == NULL) {
+		DEBUG(0, ("talloc failed\n"));
+		goto fail;
+	}
+
+	db_tdb->tdb = tdb_open_log(name, hash_size, tdb_flags,
+				   open_flags, mode);
+	if (db_tdb->tdb == NULL) {
+		DEBUG(3, ("Could not open tdb: %s\n", strerror(errno)));
+		goto fail;
+	}
+
+	talloc_set_destructor(db_tdb, db_tdb_ctx_destr);
+	result->fetch_locked = db_tdb_fetch_locked;
+	result->traverse = db_tdb_traverse;
+	result->get_seqnum = db_tdb_get_seqnum;
+	return result;
+
+ fail:
+	if (result != NULL) {
+		TALLOC_FREE(result);
+	}
+	return NULL;
+}