/*
   Partitions ldb module - management of metadata.tdb for sequence number

   Copyright (C) Amitay Isaacs <amitay@samba.org> 2011

   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "dsdb/samdb/ldb_modules/partition.h"
#include "lib/ldb-samba/ldb_wrap.h"
#include "system/filesys.h"
#include "lib/util/smb_strtox.h"

#define LDB_METADATA_SEQ_NUM	"SEQ_NUM"


/*
 * Read a key with uint64 value
 */
static int partition_metadata_get_uint64(struct ldb_module *module,
					 const char *key, uint64_t *value,
					 uint64_t default_value)
{
	struct partition_private_data *data;
	struct tdb_context *tdb;
	TDB_DATA tdb_key, tdb_data;
	char *value_str;
	int error = 0;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);

	if (!data || !data->metadata || !data->metadata->db) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata tdb not initialized");
	}

	tdb = data->metadata->db->tdb;

	tdb_key.dptr = (uint8_t *)discard_const_p(char, key);
	tdb_key.dsize = strlen(key);

	tdb_data = tdb_fetch(tdb, tdb_key);
	if (!tdb_data.dptr) {
		if (tdb_error(tdb) == TDB_ERR_NOEXIST) {
			*value = default_value;
			return LDB_SUCCESS;
		} else {
			return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
						tdb_errorstr(tdb));
		}
	}

	value_str = talloc_strndup(NULL, (char *)tdb_data.dptr, tdb_data.dsize);
	SAFE_FREE(tdb_data.dptr);
	if (value_str == NULL) {
		return ldb_module_oom(module);
	}

	*value = smb_strtoull(value_str, NULL, 10, &error, SMB_STR_STANDARD);
	talloc_free(value_str);
	if (error != 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: converision failed");
	}

	return LDB_SUCCESS;
}


/*
 * Write a key with uin64 value
 */
static int partition_metadata_set_uint64(struct ldb_module *module,
					 const char *key, uint64_t value,
					 bool insert)
{
	struct partition_private_data *data;
	struct tdb_context *tdb;
	TDB_DATA tdb_key, tdb_data;
	int tdb_flag;
	char *value_str;
	TALLOC_CTX *tmp_ctx;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);

	if (!data || !data->metadata || !data->metadata->db) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata tdb not initialized");
	}

	tmp_ctx = talloc_new(NULL);
	if (tmp_ctx == NULL) {
		return ldb_module_oom(module);
	}

	tdb = data->metadata->db->tdb;

	value_str = talloc_asprintf(tmp_ctx, "%llu", (unsigned long long)value);
	if (value_str == NULL) {
		talloc_free(tmp_ctx);
		return ldb_module_oom(module);
	}

	tdb_key.dptr = (uint8_t *)discard_const_p(char, key);
	tdb_key.dsize = strlen(key);

	tdb_data.dptr = (uint8_t *)value_str;
	tdb_data.dsize = strlen(value_str);

	if (insert) {
		tdb_flag = TDB_INSERT;
	} else {
		tdb_flag = TDB_MODIFY;
	}

	if (tdb_store(tdb, tdb_key, tdb_data, tdb_flag) != 0) {
		int ret;
		char *error_string = talloc_asprintf(tmp_ctx, "%s: tdb_store of key %s failed: %s",
						     tdb_name(tdb), key, tdb_errorstr(tdb));
		ret = ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
				       error_string);
		talloc_free(tmp_ctx);
		return ret;
	}

	talloc_free(tmp_ctx);

	return LDB_SUCCESS;
}

int partition_metadata_inc_schema_sequence(struct ldb_module *module)
{
	struct partition_private_data *data;
	int ret;
	uint64_t value = 0;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				    struct partition_private_data);
	if (!data || !data->metadata) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}

	if (data->metadata->in_transaction == 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: increment sequence number without transaction");
	}
	ret = partition_metadata_get_uint64(module, DSDB_METADATA_SCHEMA_SEQ_NUM, &value, 0);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	value++;
	ret = partition_metadata_set_uint64(module, DSDB_METADATA_SCHEMA_SEQ_NUM, value, false);
	if (ret == LDB_ERR_OPERATIONS_ERROR) {
		/* Modify failed, let's try the add */
		ret = partition_metadata_set_uint64(module, DSDB_METADATA_SCHEMA_SEQ_NUM, value, true);
	}
	return ret;
}



/*
 * Open sam.ldb.d/metadata.tdb.
 */
static int partition_metadata_open(struct ldb_module *module, bool create)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	TALLOC_CTX *tmp_ctx;
	struct partition_private_data *data;
	struct loadparm_context *lp_ctx;
	char *filename, *dirname;
	int open_flags, tdb_flags, ldb_flags;
	struct stat statbuf;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);
	if (!data || !data->metadata) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}

	tmp_ctx = talloc_new(NULL);
	if (tmp_ctx == NULL) {
		return ldb_module_oom(module);
	}

	filename = ldb_relative_path(ldb,
				     tmp_ctx,
				     "sam.ldb.d/metadata.tdb");

	if (!filename) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb);
	}

	open_flags = O_RDWR;
	if (create) {
		open_flags |= O_CREAT;

		/* While provisioning, sam.ldb.d directory may not exist,
		 * so create it. Ignore errors, if it already exists. */
		dirname = ldb_relative_path(ldb,
					    tmp_ctx,
					    "sam.ldb.d");
		if (!dirname) {
			talloc_free(tmp_ctx);
			return ldb_oom(ldb);
		}

		mkdir(dirname, 0700);
		talloc_free(dirname);
	} else {
		if (stat(filename, &statbuf) != 0) {
			talloc_free(tmp_ctx);
			return LDB_ERR_OPERATIONS_ERROR;
		}
	}

	lp_ctx = talloc_get_type_abort(ldb_get_opaque(ldb, "loadparm"),
				       struct loadparm_context);

	tdb_flags = lpcfg_tdb_flags(lp_ctx, TDB_DEFAULT|TDB_SEQNUM);

	ldb_flags = ldb_module_flags(ldb);

	if (ldb_flags & LDB_FLG_NOSYNC) {
		tdb_flags |= TDB_NOSYNC;
	}

	data->metadata->db = tdb_wrap_open(
		data->metadata, filename, 10,
		tdb_flags, open_flags, 0660);
	if (data->metadata->db == NULL) {
		talloc_free(tmp_ctx);
		if (create) {
			ldb_asprintf_errstring(ldb, "partition_metadata: Unable to create %s: %s",
					       filename, strerror(errno));
		} else {
			ldb_asprintf_errstring(ldb, "partition_metadata: Unable to open %s: %s",
					       filename, strerror(errno));
		}
		if (errno == EACCES || errno == EPERM) {
			return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
		}
		return LDB_ERR_OPERATIONS_ERROR;
	}

	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}


/*
 * Set the sequence number calculated from older logic (sum of primary sequence
 * numbers for each partition) as LDB_METADATA_SEQ_NUM key.
 */
static int partition_metadata_set_sequence_number(struct ldb_module *module)
{
	int ret;
	uint64_t seq_number;

	ret = partition_sequence_number_from_partitions(module, &seq_number);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return partition_metadata_set_uint64(module, LDB_METADATA_SEQ_NUM, seq_number, true);
}


/*
 * Initialize metadata. Load metadata.tdb.
 * If missing, create it and fill in sequence number
 */
int partition_metadata_init(struct ldb_module *module)
{
	struct partition_private_data *data;
	int ret;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);

	if (data->metadata != NULL && data->metadata->db != NULL) {
		return LDB_SUCCESS;
	}

	data->metadata = talloc_zero(data, struct partition_metadata);
	if (data->metadata == NULL) {
		return ldb_module_oom(module);
	}

	ret = partition_metadata_open(module, false);
	if (ret == LDB_SUCCESS) {
		/* Great, we got the DB open */
		return LDB_SUCCESS;
	}

	/* metadata.tdb does not exist, create it */
	DEBUG(2, ("partition_metadata: Migrating partition metadata: "
		  "open of metadata.tdb gave: %s\n",
		  ldb_errstring(ldb_module_get_ctx(module))));
	ret = partition_metadata_open(module, true);
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb_module_get_ctx(module),
				       "partition_metadata: "
				       "Migrating partition metadata: "
				       "create of metadata.tdb gave: %s\n",
				       ldb_errstring(ldb_module_get_ctx(module)));
		TALLOC_FREE(data->metadata);
		return ret;
	}

	return ret;
}


/*
 * Read the sequence number, default to 0 if LDB_METADATA_SEQ_NUM key is missing
 */
int partition_metadata_sequence_number(struct ldb_module *module, uint64_t *value)
{

	/* We have to lock all the databases as otherwise we can
	 * return a sequence number that is higher than the DB values
	 * that we can see, as those transactions close after the
	 * metadata.tdb transaction closes */
	int ret = partition_read_lock(module);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	/*
	 * This means we will give a 0 until the first write
	 * transaction, which is actually pretty reasonable.
	 *
	 * All modern databases will have the metadata.tdb from
	 * the time of the first transaction in provision anyway.
	 */
	ret = partition_metadata_get_uint64(module,
					    LDB_METADATA_SEQ_NUM,
					    value,
					    0);
	if (ret == LDB_SUCCESS) {
		ret = partition_read_unlock(module);
	} else {
		/* Don't overwrite the error code */
		partition_read_unlock(module);
	}
	return ret;

}


/*
 * Increment the sequence number, returning the new sequence number
 */
int partition_metadata_sequence_number_increment(struct ldb_module *module, uint64_t *value)
{
	struct partition_private_data *data;
	int ret;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				    struct partition_private_data);
	if (!data || !data->metadata) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}

	if (data->metadata->in_transaction == 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: increment sequence number without transaction");
	}

	ret = partition_metadata_get_uint64(module, LDB_METADATA_SEQ_NUM, value, 0);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (*value == 0) {
		/*
		 * We are in a transaction now, so we can get the
		 * sequence number from the partitions.
		 */
		ret = partition_metadata_set_sequence_number(module);
		if (ret != LDB_SUCCESS) {
			return ret;
		}

		ret = partition_metadata_get_uint64(module,
						    LDB_METADATA_SEQ_NUM,
						    value, 0);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
	}

	(*value)++;
	ret = partition_metadata_set_uint64(module, LDB_METADATA_SEQ_NUM, *value, false);
	return ret;
}
/*
  lock the database for read - use by partition_lock_read
*/
int partition_metadata_read_lock(struct ldb_module *module)
{
	struct partition_private_data *data
		= talloc_get_type_abort(ldb_module_get_private(module),
					struct partition_private_data);
	struct tdb_context *tdb = NULL;
	int tdb_ret = 0;
	int ret;

	if (!data || !data->metadata || !data->metadata->db) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}
	tdb = data->metadata->db->tdb;

	if (tdb_transaction_active(tdb) == false &&
	    data->metadata->read_lock_count == 0) {
		tdb_ret = tdb_lockall_read(tdb);
	}
	if (tdb_ret == 0) {
		data->metadata->read_lock_count++;
		return LDB_SUCCESS;
	} else {
		/* Sadly we can't call ltdb_err_map(tdb_error(tdb)); */
		ret = LDB_ERR_BUSY;
	}
	ldb_debug_set(ldb_module_get_ctx(module),
		      LDB_DEBUG_FATAL,
		      "Failure during partition_metadata_read_lock(): %s",
		      tdb_errorstr(tdb));
	return ret;
}

/*
  unlock the database after a partition_metadata_lock_read()
*/
int partition_metadata_read_unlock(struct ldb_module *module)
{
	struct partition_private_data *data
		= talloc_get_type_abort(ldb_module_get_private(module),
					struct partition_private_data);
	struct tdb_context *tdb = NULL;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);
	if (!data || !data->metadata || !data->metadata->db) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}
	tdb = data->metadata->db->tdb;

	if (!tdb_transaction_active(tdb) &&
	    data->metadata->read_lock_count == 1) {
		tdb_unlockall_read(tdb);
		data->metadata->read_lock_count--;
		return 0;
	}
	data->metadata->read_lock_count--;
	return 0;
}


/*
 * Transaction start
 */
int partition_metadata_start_trans(struct ldb_module *module)
{
	struct partition_private_data *data;
	struct tdb_context *tdb;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);
	if (!data || !data->metadata || !data->metadata->db) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}
	tdb = data->metadata->db->tdb;

	if (tdb_transaction_start(tdb) != 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					tdb_errorstr(tdb));
	}

	data->metadata->in_transaction++;

	return LDB_SUCCESS;
}


/*
 * Transaction prepare commit
 */
int partition_metadata_prepare_commit(struct ldb_module *module)
{
	struct partition_private_data *data;
	struct tdb_context *tdb;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);
	if (!data || !data->metadata || !data->metadata->db) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}
	tdb = data->metadata->db->tdb;

	if (data->metadata->in_transaction == 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: not in transaction");
	}

	if (tdb_transaction_prepare_commit(tdb) != 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					tdb_errorstr(tdb));
	}

	return LDB_SUCCESS;
}


/*
 * Transaction end
 */
int partition_metadata_end_trans(struct ldb_module *module)
{
	struct partition_private_data *data;
	struct tdb_context *tdb;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);
	if (!data || !data->metadata || !data->metadata->db) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}
	tdb = data->metadata->db->tdb;

	if (data->metadata->in_transaction == 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: not in transaction");
	}

	data->metadata->in_transaction--;

	if (tdb_transaction_commit(tdb) != 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					tdb_errorstr(tdb));
	}

	return LDB_SUCCESS;
}


/*
 * Transaction delete
 */
int partition_metadata_del_trans(struct ldb_module *module)
{
	struct partition_private_data *data;
	struct tdb_context *tdb;

	data = talloc_get_type_abort(ldb_module_get_private(module),
				     struct partition_private_data);
	if (!data || !data->metadata || !data->metadata->db) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: metadata not initialized");
	}
	tdb = data->metadata->db->tdb;

	if (data->metadata->in_transaction == 0) {
		return ldb_module_error(module, LDB_ERR_OPERATIONS_ERROR,
					"partition_metadata: not in transaction");
	}

	data->metadata->in_transaction--;

	tdb_transaction_cancel(tdb);

	return LDB_SUCCESS;
}