settings: Add update/getPersistent/isIgnored methods

Add interfaces::Node methods to give GUI finer grained control over
settings.json file. Update method is used to write settings to the file,
getPersistent and isIgnored methods are used to find out about settings
file and command line option interactions.

src/util/settings.cpp

@@ -127,6 +127,7 @@ SettingsValue GetSetting(const Settings& settings,
     const std::string& section,
     const std::string& name,
     bool ignore_default_section_config,
+    bool ignore_nonpersistent,
     bool get_chain_name)
 {
     SettingsValue result;
@@ -162,6 +163,9 @@ SettingsValue GetSetting(const Settings& settings,
             return;
         }
 
+        // Ignore nonpersistent settings if requested.
+        if (ignore_nonpersistent && (source == Source::COMMAND_LINE || source == Source::FORCED)) return;
+
         // Skip negated command line settings.
         if (skip_negated_command_line && span.last_negated()) return;
 

src/util/settings.h

@@ -55,12 +55,18 @@ bool WriteSettings(const fs::path& path,
 //! @param ignore_default_section_config - ignore values in the default section
 //!                                        of the config file (part before any
 //!                                        [section] keywords)
+//! @param ignore_nonpersistent - ignore non-persistent settings values (forced
+//!                               settings values and values specified on the
+//!                               command line). Only return settings in the
+//!                               read-only config and read-write settings
+//!                               files.
 //! @param get_chain_name - enable special backwards compatible behavior
 //!                         for GetChainName
 SettingsValue GetSetting(const Settings& settings,
     const std::string& section,
     const std::string& name,
     bool ignore_default_section_config,
+    bool ignore_nonpersistent,
     bool get_chain_name);
 
 //! Get combined setting value similar to GetSetting(), except if setting was

src/util/system.cpp

@@ -592,6 +592,13 @@ bool ArgsManager::WriteSettingsFile(std::vector<std::string>* errors) const
     return true;
 }
 
+util::SettingsValue ArgsManager::GetPersistentSetting(const std::string& name) const
+{
+    LOCK(cs_args);
+    return util::GetSetting(m_settings, m_network, name, !UseDefaultSection("-" + name),
+        /*ignore_nonpersistent=*/true, /*get_chain_name=*/false);
+}
+
 bool ArgsManager::IsArgNegated(const std::string& strArg) const
 {
     return GetSetting(strArg).isFalse();
@@ -600,18 +607,33 @@ bool ArgsManager::IsArgNegated(const std::string& strArg) const
 std::string ArgsManager::GetArg(const std::string& strArg, const std::string& strDefault) const
 {
     const util::SettingsValue value = GetSetting(strArg);
+    return SettingToString(value, strDefault);
+}
+
+std::string SettingToString(const util::SettingsValue& value, const std::string& strDefault)
+{
     return value.isNull() ? strDefault : value.isFalse() ? "0" : value.isTrue() ? "1" : value.isNum() ? value.getValStr() : value.get_str();
 }
 
 int64_t ArgsManager::GetIntArg(const std::string& strArg, int64_t nDefault) const
 {
     const util::SettingsValue value = GetSetting(strArg);
+    return SettingToInt(value, nDefault);
+}
+
+int64_t SettingToInt(const util::SettingsValue& value, int64_t nDefault)
+{
     return value.isNull() ? nDefault : value.isFalse() ? 0 : value.isTrue() ? 1 : value.isNum() ? value.getInt<int64_t>() : LocaleIndependentAtoi<int64_t>(value.get_str());
 }
 
 bool ArgsManager::GetBoolArg(const std::string& strArg, bool fDefault) const
 {
     const util::SettingsValue value = GetSetting(strArg);
+    return SettingToBool(value, fDefault);
+}
+
+bool SettingToBool(const util::SettingsValue& value, bool fDefault)
+{
     return value.isNull() ? fDefault : value.isBool() ? value.get_bool() : InterpretBool(value.get_str());
 }
 
@@ -1002,6 +1024,7 @@ std::string ArgsManager::GetChainName() const
         LOCK(cs_args);
         util::SettingsValue value = util::GetSetting(m_settings, /* section= */ "", SettingName(arg),
             /* ignore_default_section_config= */ false,
+            /*ignore_nonpersistent=*/false,
             /* get_chain_name= */ true);
         return value.isNull() ? false : value.isBool() ? value.get_bool() : InterpretBool(value.get_str());
     };
@@ -1034,7 +1057,8 @@ util::SettingsValue ArgsManager::GetSetting(const std::string& arg) const
 {
     LOCK(cs_args);
     return util::GetSetting(
-        m_settings, m_network, SettingName(arg), !UseDefaultSection(arg), /* get_chain_name= */ false);
+        m_settings, m_network, SettingName(arg), !UseDefaultSection(arg),
+        /*ignore_nonpersistent=*/false, /*get_chain_name=*/false);
 }
 
 std::vector<util::SettingsValue> ArgsManager::GetSettingsList(const std::string& arg) const

src/util/system.h

@@ -161,6 +161,10 @@ struct SectionInfo
     int m_line;
 };
 
+std::string SettingToString(const util::SettingsValue&, const std::string&);
+int64_t SettingToInt(const util::SettingsValue&, int64_t);
+bool SettingToBool(const util::SettingsValue&, bool);
+
 class ArgsManager
 {
 public:
@@ -448,6 +452,12 @@ protected:
      */
     bool WriteSettingsFile(std::vector<std::string>* errors = nullptr) const;
 
+    /**
+     * Get current setting from config file or read/write settings file,
+     * ignoring nonpersistent command line or forced settings values.
+     */
+    util::SettingsValue GetPersistentSetting(const std::string& name) const;
+
     /**
      * Access settings with lock held.
      */