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.

7 files changed, 101 insertions, 10 deletions

diff --git a/src/interfaces/node.h b/src/interfaces/node.h
index c4dc303dd5..1585174a6f 100644
--- a/src/interfaces/node.h
+++ b/src/interfaces/node.h
@@ -5,12 +5,13 @@
 #ifndef BITCOIN_INTERFACES_NODE_H
 #define BITCOIN_INTERFACES_NODE_H
 
-#include <consensus/amount.h>
-#include <net.h>        // For NodeId
-#include <net_types.h>  // For banmap_t
-#include <netaddress.h> // For Network
-#include <netbase.h>    // For ConnectionDirection
+#include <consensus/amount.h>          // For CAmount
+#include <net.h>                       // For NodeId
+#include <net_types.h>                 // For banmap_t
+#include <netaddress.h>                // For Network
+#include <netbase.h>                   // For ConnectionDirection
 #include <support/allocators/secure.h> // For SecureString
+#include <util/settings.h>             // For util::SettingsValue
 #include <util/translation.h>
 
 #include <functional>
@@ -97,6 +98,20 @@ public:
     //! Return whether shutdown was requested.
     virtual bool shutdownRequested() = 0;
 
+    //! Return whether a particular setting in <datadir>/settings.json is or
+    //! would be ignored because it is also specified in the command line.
+    virtual bool isSettingIgnored(const std::string& name) = 0;
+
+    //! Return setting value from <datadir>/settings.json or bitcoin.conf.
+    virtual util::SettingsValue getPersistentSetting(const std::string& name) = 0;
+
+    //! Update a setting in <datadir>/settings.json.
+    virtual void updateRwSetting(const std::string& name, const util::SettingsValue& value) = 0;
+
+    //! Force a setting value to be applied, overriding any other configuration
+    //! source, but not being persisted.
+    virtual void forceSetting(const std::string& name, const util::SettingsValue& value) = 0;
+
     //! Map port.
     virtual void mapPort(bool use_upnp, bool use_natpmp) = 0;
 
diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
index f2debc790c..09404a5f85 100644
--- a/src/node/interfaces.cpp
+++ b/src/node/interfaces.cpp
@@ -112,6 +112,38 @@ public:
         }
     }
     bool shutdownRequested() override { return ShutdownRequested(); }
+    bool isSettingIgnored(const std::string& name) override
+    {
+        bool ignored = false;
+        gArgs.LockSettings([&](util::Settings& settings) {
+            if (auto* options = util::FindKey(settings.command_line_options, name)) {
+                ignored = !options->empty();
+            }
+        });
+        return ignored;
+    }
+    util::SettingsValue getPersistentSetting(const std::string& name) override { return gArgs.GetPersistentSetting(name); }
+    void updateRwSetting(const std::string& name, const util::SettingsValue& value) override
+    {
+        gArgs.LockSettings([&](util::Settings& settings) {
+            if (value.isNull()) {
+                settings.rw_settings.erase(name);
+            } else {
+                settings.rw_settings[name] = value;
+            }
+        });
+        gArgs.WriteSettingsFile();
+    }
+    void forceSetting(const std::string& name, const util::SettingsValue& value) override
+    {
+        gArgs.LockSettings([&](util::Settings& settings) {
+            if (value.isNull()) {
+                settings.forced_settings.erase(name);
+            } else {
+                settings.forced_settings[name] = value;
+            }
+        });
+    }
     void mapPort(bool use_upnp, bool use_natpmp) override { StartMapPort(use_upnp, use_natpmp); }
     bool getProxy(Network net, Proxy& proxy_info) override { return GetProxy(net, proxy_info); }
     size_t getNodeCount(ConnectionDirection flags) override
diff --git a/src/test/settings_tests.cpp b/src/test/settings_tests.cpp
index 15ffd068c7..0feb68b9b1 100644
--- a/src/test/settings_tests.cpp
+++ b/src/test/settings_tests.cpp
@@ -105,7 +105,7 @@ BOOST_AUTO_TEST_CASE(ReadWrite)
 //! Check settings struct contents against expected json strings.
 static void CheckValues(const util::Settings& settings, const std::string& single_val, const std::string& list_val)
 {
-    util::SettingsValue single_value = GetSetting(settings, "section", "name", false, false);
+    util::SettingsValue single_value = GetSetting(settings, "section", "name", false, false, false);
     util::SettingsValue list_value(util::SettingsValue::VARR);
     for (const auto& item : GetSettingsList(settings, "section", "name", false)) {
         list_value.push_back(item);
@@ -141,9 +141,9 @@ BOOST_AUTO_TEST_CASE(NullOverride)
 {
     util::Settings settings;
     settings.command_line_options["name"].push_back("value");
-    BOOST_CHECK_EQUAL(R"("value")", GetSetting(settings, "section", "name", false, false).write().c_str());
+    BOOST_CHECK_EQUAL(R"("value")", GetSetting(settings, "section", "name", false, false, false).write().c_str());
     settings.forced_settings["name"] = {};
-    BOOST_CHECK_EQUAL(R"(null)", GetSetting(settings, "section", "name", false, false).write().c_str());
+    BOOST_CHECK_EQUAL(R"(null)", GetSetting(settings, "section", "name", false, false, false).write().c_str());
 }
 
 // Test different ways settings can be merged, and verify results. This test can
@@ -224,7 +224,7 @@ BOOST_FIXTURE_TEST_CASE(Merge, MergeTestingSetup)
         }
 
         desc += " || ";
-        desc += GetSetting(settings, network, name, ignore_default_section_config, /* get_chain_name= */ false).write();
+        desc += GetSetting(settings, network, name, ignore_default_section_config, /*ignore_nonpersistent=*/false, /*get_chain_name=*/false).write();
         desc += " |";
         for (const auto& s : GetSettingsList(settings, network, name, ignore_default_section_config)) {
             desc += " ";
diff --git a/src/util/settings.cpp b/src/util/settings.cpp
index 26439b010b..924a9cfab2 100644
--- a/src/util/settings.cpp
+++ b/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;
 
diff --git a/src/util/settings.h b/src/util/settings.h
index 261a0a032f..e97158dc09 100644
--- a/src/util/settings.h
+++ b/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
diff --git a/src/util/system.cpp b/src/util/system.cpp
index cbe9d2ceb0..87d3be9d23 100644
--- a/src/util/system.cpp
+++ b/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
diff --git a/src/util/system.h b/src/util/system.h
index a7f4d16911..bfc9698221 100644
--- a/src/util/system.h
+++ b/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:
@@ -449,6 +453,12 @@ 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.
      */
     template <typename Fn>