int mail_transaction_log_create(struct mail_transaction_log *log, bool reset)
{
	struct mail_transaction_log_file *file;

	if (MAIL_INDEX_IS_IN_MEMORY(log->index)) {
		file = mail_transaction_log_file_alloc_in_memory(log);
		mail_transaction_log_set_head(log, file);
		return 0;
	}

	file = mail_transaction_log_file_alloc(log, log->filepath);
	if (log->open_file != NULL) {
		/* remember what file we tried to open. if someone else created
		   a new file, use it instead of recreating it */
		file->st_ino = log->open_file->st_ino;
		file->st_dev = log->open_file->st_dev;
		file->last_size = log->open_file->last_size;
		file->last_mtime = log->open_file->last_mtime;
		mail_transaction_log_file_free(&log->open_file);
	}

	if (mail_transaction_log_file_create(file, reset) < 0) {
		mail_transaction_log_file_free(&file);
		return -1;
	}

	mail_transaction_log_set_head(log, file);
	return 1;
}
int mail_transaction_log_open(struct mail_transaction_log *log)
{
	struct mail_transaction_log_file *file;
	const char *reason;
	int ret;

	i_free(log->filepath);
	i_free(log->filepath2);
	log->filepath = i_strconcat(log->index->filepath,
				    MAIL_TRANSACTION_LOG_SUFFIX, NULL);
	log->filepath2 = i_strconcat(log->filepath, ".2", NULL);

	/* these settings aren't available at alloc() time, so we need to
	   set them here: */
	log->nfs_flush =
		(log->index->flags & MAIL_INDEX_OPEN_FLAG_NFS_FLUSH) != 0;

	if (log->open_file != NULL)
		mail_transaction_log_file_free(&log->open_file);

	if (MAIL_INDEX_IS_IN_MEMORY(log->index))
		return 0;

	file = mail_transaction_log_file_alloc(log, log->filepath);
	if ((ret = mail_transaction_log_file_open(file, &reason)) <= 0) {
		/* leave the file for _create() */
		log->open_file = file;
		return ret;
	}
	mail_transaction_log_set_head(log, file);
	return 1;
}
static int
mail_transaction_log_refresh(struct mail_transaction_log *log, bool nfs_flush)
{
        struct mail_transaction_log_file *file;
	struct stat st;

	i_assert(log->head != NULL);

	if (MAIL_TRANSACTION_LOG_FILE_IN_MEMORY(log->head))
		return 0;

	if (nfs_flush && log->nfs_flush)
		nfs_flush_file_handle_cache(log->filepath);
	if (nfs_safe_stat(log->filepath, &st) < 0) {
		if (errno != ENOENT) {
			mail_index_file_set_syscall_error(log->index,
							  log->filepath,
							  "stat()");
			return -1;
		}
		/* see if the whole directory got deleted */
		if (nfs_safe_stat(log->index->dir, &st) < 0 &&
		    errno == ENOENT) {
			log->index->index_deleted = TRUE;
			return -1;
		}

		/* the file should always exist at this point. if it doesn't,
		   someone deleted it manually while the index was open. try to
		   handle this nicely by creating a new log file. */
		file = log->head;
		if (mail_transaction_log_create(log, FALSE) < 0)
			return -1;
		i_assert(file->refcount > 0);
		file->refcount--;
		log->index->need_recreate = TRUE;
		return 0;
	} else if (log->head->st_ino == st.st_ino &&
		   CMP_DEV_T(log->head->st_dev, st.st_dev)) {
		/* NFS: log files get rotated to .log.2 files instead
		   of being unlinked, so we don't bother checking if
		   the existing file has already been unlinked here
		   (in which case inodes could match but point to
		   different files) */
		return 0;
	}

	file = mail_transaction_log_file_alloc(log, log->filepath);
	if (mail_transaction_log_file_open(file, FALSE) <= 0) {
		mail_transaction_log_file_free(&file);
		return -1;
	}

	i_assert(!file->locked);

	if (--log->head->refcount == 0)
		mail_transaction_logs_clean(log);
	mail_transaction_log_set_head(log, file);
	return 0;
}
int mail_transaction_log_rotate(struct mail_transaction_log *log, bool reset)
{
	struct mail_transaction_log_file *file;
	const char *path = log->head->filepath;
	struct stat st;
	int ret;

	i_assert(log->head->locked);

	if (MAIL_INDEX_IS_IN_MEMORY(log->index)) {
		file = mail_transaction_log_file_alloc_in_memory(log);
		if (reset) {
			file->hdr.prev_file_seq = 0;
			file->hdr.prev_file_offset = 0;
		}
	} else {
                /* we're locked, we shouldn't need to worry about ESTALE
                   problems in here. */
		if (fstat(log->head->fd, &st) < 0) {
			mail_index_file_set_syscall_error(log->index,
				log->head->filepath, "fstat()");
			return -1;
		}

		file = mail_transaction_log_file_alloc(log, path);

		file->st_dev = st.st_dev;
		file->st_ino = st.st_ino;
		file->last_mtime = st.st_mtime;
		file->last_size = st.st_size;

		if ((ret = mail_transaction_log_file_create(file, reset)) < 0) {
			mail_transaction_log_file_free(&file);
			return -1;
		}
		if (ret == 0) {
			mail_index_set_error(log->index,
				"Transaction log %s was recreated while we had it locked - "
				"locking is broken (lock_method=%s)", path,
				file_lock_method_to_str(log->index->lock_method));
			mail_transaction_log_file_free(&file);
			return -1;
		}
		i_assert(file->locked);
	}

	if (--log->head->refcount == 0)
		mail_transaction_logs_clean(log);
	else {
		/* the newly created log file is already locked */
		mail_transaction_log_file_unlock(log->head,
			!log->index->log_sync_locked ? "rotating" :
			"rotating while syncing");
	}
	mail_transaction_log_set_head(log, file);
	return 0;
}
int mail_transaction_log_rotate(struct mail_transaction_log *log, bool reset)
{
	struct mail_transaction_log_file *file;
	const char *path = log->head->filepath;
	struct stat st;

	i_assert(log->head->locked);

	if (MAIL_INDEX_IS_IN_MEMORY(log->index)) {
		file = mail_transaction_log_file_alloc_in_memory(log);
		if (reset) {
			file->hdr.prev_file_seq = 0;
			file->hdr.prev_file_offset = 0;
		}
	} else {
                /* we're locked, we shouldn't need to worry about ESTALE
                   problems in here. */
		if (fstat(log->head->fd, &st) < 0) {
			mail_index_file_set_syscall_error(log->index,
				log->head->filepath, "fstat()");
			return -1;
		}

		file = mail_transaction_log_file_alloc(log, path);

		file->st_dev = st.st_dev;
		file->st_ino = st.st_ino;
		file->last_mtime = st.st_mtime;
		file->last_size = st.st_size;

		if (mail_transaction_log_file_create(file, reset) < 0) {
			mail_transaction_log_file_free(&file);
			return -1;
		}
	}

	if (--log->head->refcount == 0)
		mail_transaction_logs_clean(log);
	else
		mail_transaction_log_file_unlock(log->head);
	mail_transaction_log_set_head(log, file);
	return 0;
}
void mail_transaction_log_move_to_memory(struct mail_transaction_log *log)
{
	struct mail_transaction_log_file *file;

	if (!log->index->initial_mapped && log->files != NULL &&
	    log->files->hdr.prev_file_seq != 0) {
		/* we couldn't read dovecot.index and we don't have the first
		   .log file, so just start from scratch */
		mail_transaction_log_close(log);
	}

	i_free(log->filepath);
	i_free(log->filepath2);
	log->filepath = i_strconcat(log->index->filepath,
				    MAIL_TRANSACTION_LOG_SUFFIX, NULL);
	log->filepath2 = i_strconcat(log->filepath, ".2", NULL);

	if (log->head != NULL)
		mail_transaction_log_file_move_to_memory(log->head);
	else {
		file = mail_transaction_log_file_alloc_in_memory(log);
		mail_transaction_log_set_head(log, file);
	}
}