backend.h

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/* Copyright (c) 2021, 2024, Oracle and/or its affiliates.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.
 
   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, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef KEYRING_FILE_BACKEND_INCLUDED
#define KEYRING_FILE_BACKEND_INCLUDED
 
#include <string>
 
#include <components/keyrings/common/json_data/json_writer.h>
#include <components/keyrings/common/memstore/iterator.h>
#include <components/keyrings/common/operations/operations.h>
 
namespace keyring_file::backend {
 
class Keyring_file_backend final {
 public:
  explicit Keyring_file_backend(const std::string &keyring_file_name,
                                bool read_only);
 
  ~Keyring_file_backend() = default;
 
  /**
    Fetch data
 
    @param [in]  metadata Key
    @param [out] data     Value
 
    @returns Status of find operation
      @retval false Entry found. Check data.
      @retval true  Entry missing.
  */
  bool get(const keyring_common::meta::Metadata &metadata,
           keyring_common::data::Data &data) const;
 
  /**
    Store data
 
    @param [in]      metadata Key
    @param [in, out] data     Value
 
    @returns Status of store operation
      @retval false Entry stored successfully
      @retval true  Failure
  */
 
  bool store(const keyring_common::meta::Metadata &metadata,
             keyring_common::data::Data &data);
 
  /**
    Erase data located at given key
 
    @param [in] metadata Key
    @param [in] data     Value - not used.
 
    @returns Status of erase operation
      @retval false Data deleted
      @retval true  Could not find or delete data
  */
  bool erase(const keyring_common::meta::Metadata &metadata,
             keyring_common::data::Data &data);
 
  /**
    Generate random data and store it
 
    @param [in]  metadata Key
    @param [out] data     Generated value
    @param [in]  length   Length of data to be generated
 
    @returns Status of generate + store operation
      @retval false Data generated and stored successfully
      @retval true  Error
 
  */
  bool generate(const keyring_common::meta::Metadata &metadata,
                keyring_common::data::Data &data, size_t length);
 
  /**
    Populate cache
 
    @param [in] operations  Handle to operations class
 
    @returns status of cache insertion
      @retval false Success
      @retval true  Failure
  */
  bool load_cache(
      keyring_common::operations::Keyring_operations<Keyring_file_backend>
          &operations);
 
  /** Maximum data length supported */
  size_t maximum_data_length() const { return 16384; }
 
  /** Get number of elements stored in backend */
  size_t size() const { return json_writer_.num_elements(); }
 
  /** Validity */
  bool valid() const { return valid_; }
 
 private:
  /**
    Write existing data to file.
    This function overwrites existing data stored in the file.
 
    @returns Status of write operation.
      @retval false Successfully written data to file
      @retval true  Error writing data to file
  */
  bool write_to_file();
 
  /** Create data file if missing */
  void create_file_if_missing(const std::string &file_name);
 
 private:
  /** Keyring file */
  std::string keyring_file_name_;
 
  /** Read only flag */
  bool read_only_;
 
  /** In memory cache for keyring data */
  keyring_common::json_data::Json_writer json_writer_;
 
  /** Validity */
  bool valid_;
};
 
}  // namespace keyring_file::backend
 
#endif  // !KEYRING_FILE_BACKEND_INCLUDED