1  // Copyright (c) 2019-present The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #ifndef BITCOIN_COMMON_SETTINGS_H
  6  #define BITCOIN_COMMON_SETTINGS_H
  7  
  8  #include <util/fs.h>
  9  
 10  #include <cstddef>
 11  #include <map>
 12  #include <string>
 13  #include <vector>
 14  
 15  class UniValue;
 16  
 17  namespace common {
 18  
 19  //! Settings value type (string/integer/boolean/null variant).
 20  //!
 21  //! @note UniValue is used here for convenience and because it can be easily
 22  //!       serialized in a readable format. But any other variant type that can
 23  //!       be assigned strings, int64_t, and bool values and has get_str(),
 24  //!       getInt<int64_t>(), get_bool(), isNum(), isBool(), isFalse(), isTrue() and
 25  //!       isNull() methods can be substituted if there's a need to move away
 26  //!       from UniValue. (An implementation with boost::variant was posted at
 27  //!       https://github.com/bitcoin/bitcoin/pull/15934/files#r337691812)
 28  using SettingsValue = UniValue;
 29  
 30  //! Stored settings. This struct combines settings from the command line, a
 31  //! read-only configuration file, and a read-write runtime settings file.
 32  struct Settings {
 33      //! Map of setting name to forced setting value.
 34      std::map<std::string, SettingsValue> forced_settings;
 35      //! Map of setting name to list of command line values.
 36      std::map<std::string, std::vector<SettingsValue>> command_line_options;
 37      //! Map of setting name to read-write file setting value.
 38      std::map<std::string, SettingsValue> rw_settings;
 39      //! Map of config section name and setting name to list of config file values.
 40      std::map<std::string, std::map<std::string, std::vector<SettingsValue>>> ro_config;
 41  };
 42  
 43  //! Read settings file.
 44  bool ReadSettings(const fs::path& path,
 45      std::map<std::string, SettingsValue>& values,
 46      std::vector<std::string>& errors);
 47  
 48  //! Write settings file.
 49  bool WriteSettings(const fs::path& path,
 50      const std::map<std::string, SettingsValue>& values,
 51      std::vector<std::string>& errors);
 52  
 53  //! Get settings value from combined sources: forced settings, command line
 54  //! arguments, runtime read-write settings, and the read-only config file.
 55  //!
 56  //! @param ignore_default_section_config - ignore values in the default section
 57  //!                                        of the config file (part before any
 58  //!                                        [section] keywords)
 59  //! @param ignore_nonpersistent - ignore non-persistent settings values (forced
 60  //!                               settings values and values specified on the
 61  //!                               command line). Only return settings in the
 62  //!                               read-only config and read-write settings
 63  //!                               files.
 64  //! @param get_chain_type - enable special backwards compatible behavior
 65  //!                         for GetChainType
 66  SettingsValue GetSetting(const Settings& settings,
 67      const std::string& section,
 68      const std::string& name,
 69      bool ignore_default_section_config,
 70      bool ignore_nonpersistent,
 71      bool get_chain_type);
 72  
 73  //! Get combined setting value similar to GetSetting(), except if setting was
 74  //! specified multiple times, return a list of all the values specified.
 75  std::vector<SettingsValue> GetSettingsList(const Settings& settings,
 76      const std::string& section,
 77      const std::string& name,
 78      bool ignore_default_section_config);
 79  
 80  //! Return true if a setting is set in the default config file section, and not
 81  //! overridden by a higher priority command-line or network section value.
 82  //!
 83  //! This is used to provide user warnings about values that might be getting
 84  //! ignored unintentionally.
 85  bool OnlyHasDefaultSectionSetting(const Settings& settings, const std::string& section, const std::string& name);
 86  
 87  //! Accessor for list of settings that skips negated values when iterated over.
 88  //! The last boolean `false` value in the list and all earlier values are
 89  //! considered negated.
 90  struct SettingsSpan {
 91      explicit SettingsSpan() = default;
 92      explicit SettingsSpan(const SettingsValue& value) noexcept : SettingsSpan(&value, 1) {}
 93      explicit SettingsSpan(const SettingsValue* data, size_t size) noexcept : data(data), size(size) {}
 94      explicit SettingsSpan(const std::vector<SettingsValue>& vec) noexcept;
 95      const SettingsValue* begin() const; //!< Pointer to first non-negated value.
 96      const SettingsValue* end() const;   //!< Pointer to end of values.
 97      bool empty() const;                 //!< True if there are any non-negated values.
 98      bool last_negated() const;          //!< True if the last value is negated.
 99      size_t negated() const;             //!< Number of negated values.
100  
101      const SettingsValue* data = nullptr;
102      size_t size = 0;
103  };
104  
105  //! Map lookup helper.
106  template <typename Map, typename Key>
107  auto FindKey(Map&& map, Key&& key) -> decltype(&map.at(key))
108  {
109      auto it = map.find(key);
110      return it == map.end() ? nullptr : &it->second;
111  }
112  
113  } // namespace common
114  
115  #endif // BITCOIN_COMMON_SETTINGS_H