Deduplicate settings merge code

Get rid of settings merging code in util/system.cpp repeated 5 places,
inconsistently:

- ArgsManagerHelper::GetArg
- ArgsManagerHelper::GetNetBoolArg
- ArgsManager::GetArgs
- ArgsManager::IsArgNegated
- ArgsManager::GetUnsuitableSectionOnlyArgs

Having settings merging code separated from parsing simplifies parsing somewhat
(for example negated values can simply be represented as false values instead
of partially cleared or emply placeholder lists).

Having settings merge happen one place instead of 5 makes it easier to add new
settings sources and harder to introduce new inconsistencies in the way
settings are merged.

This commit does not change behavior in any way.

3 files changed, 172 insertions, 270 deletions

diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index daf6d951bc..b9fcd97a8f 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -17,6 +17,7 @@
 
 #include <stdint.h>
 #include <thread>
+#include <univalue.h>
 #include <utility>
 #include <vector>
 #ifndef WIN32
@@ -166,14 +167,12 @@ BOOST_AUTO_TEST_CASE(util_FormatISO8601Date)
 struct TestArgsManager : public ArgsManager
 {
     TestArgsManager() { m_network_only_args.clear(); }
-    std::map<std::string, std::vector<std::string> >& GetOverrideArgs() { return m_override_args; }
-    std::map<std::string, std::vector<std::string> >& GetConfigArgs() { return m_config_args; }
     void ReadConfigString(const std::string str_config)
     {
         std::istringstream streamConfig(str_config);
         {
             LOCK(cs_args);
-            m_config_args.clear();
+            m_settings.ro_config.clear();
             m_config_sections.clear();
         }
         std::string error;
@@ -193,6 +192,7 @@ struct TestArgsManager : public ArgsManager
     using ArgsManager::ReadConfigStream;
     using ArgsManager::cs_args;
     using ArgsManager::m_network;
+    using ArgsManager::m_settings;
 };
 
 BOOST_AUTO_TEST_CASE(util_ParseParameters)
@@ -206,28 +206,29 @@ BOOST_AUTO_TEST_CASE(util_ParseParameters)
     const char *argv_test[] = {"-ignored", "-a", "-b", "-ccc=argument", "-ccc=multiple", "f", "-d=e"};
 
     std::string error;
+    LOCK(testArgs.cs_args);
     testArgs.SetupArgs({a, b, ccc, d});
     BOOST_CHECK(testArgs.ParseParameters(0, (char**)argv_test, error));
-    BOOST_CHECK(testArgs.GetOverrideArgs().empty() && testArgs.GetConfigArgs().empty());
+    BOOST_CHECK(testArgs.m_settings.command_line_options.empty() && testArgs.m_settings.ro_config.empty());
 
     BOOST_CHECK(testArgs.ParseParameters(1, (char**)argv_test, error));
-    BOOST_CHECK(testArgs.GetOverrideArgs().empty() && testArgs.GetConfigArgs().empty());
+    BOOST_CHECK(testArgs.m_settings.command_line_options.empty() && testArgs.m_settings.ro_config.empty());
 
     BOOST_CHECK(testArgs.ParseParameters(7, (char**)argv_test, error));
     // expectation: -ignored is ignored (program name argument),
     // -a, -b and -ccc end up in map, -d ignored because it is after
     // a non-option argument (non-GNU option parsing)
-    BOOST_CHECK(testArgs.GetOverrideArgs().size() == 3 && testArgs.GetConfigArgs().empty());
+    BOOST_CHECK(testArgs.m_settings.command_line_options.size() == 3 && testArgs.m_settings.ro_config.empty());
     BOOST_CHECK(testArgs.IsArgSet("-a") && testArgs.IsArgSet("-b") && testArgs.IsArgSet("-ccc")
                 && !testArgs.IsArgSet("f") && !testArgs.IsArgSet("-d"));
-    BOOST_CHECK(testArgs.GetOverrideArgs().count("-a") && testArgs.GetOverrideArgs().count("-b") && testArgs.GetOverrideArgs().count("-ccc")
-                && !testArgs.GetOverrideArgs().count("f") && !testArgs.GetOverrideArgs().count("-d"));
-
-    BOOST_CHECK(testArgs.GetOverrideArgs()["-a"].size() == 1);
-    BOOST_CHECK(testArgs.GetOverrideArgs()["-a"].front() == "");
-    BOOST_CHECK(testArgs.GetOverrideArgs()["-ccc"].size() == 2);
-    BOOST_CHECK(testArgs.GetOverrideArgs()["-ccc"].front() == "argument");
-    BOOST_CHECK(testArgs.GetOverrideArgs()["-ccc"].back() == "multiple");
+    BOOST_CHECK(testArgs.m_settings.command_line_options.count("a") && testArgs.m_settings.command_line_options.count("b") && testArgs.m_settings.command_line_options.count("ccc")
+                && !testArgs.m_settings.command_line_options.count("f") && !testArgs.m_settings.command_line_options.count("d"));
+
+    BOOST_CHECK(testArgs.m_settings.command_line_options["a"].size() == 1);
+    BOOST_CHECK(testArgs.m_settings.command_line_options["a"].front().get_str() == "");
+    BOOST_CHECK(testArgs.m_settings.command_line_options["ccc"].size() == 2);
+    BOOST_CHECK(testArgs.m_settings.command_line_options["ccc"].front().get_str() == "argument");
+    BOOST_CHECK(testArgs.m_settings.command_line_options["ccc"].back().get_str() == "multiple");
     BOOST_CHECK(testArgs.GetArgs("-ccc").size() == 2);
 }
 
@@ -298,6 +299,7 @@ BOOST_AUTO_TEST_CASE(util_GetBoolArg)
     const char *argv_test[] = {
         "ignored", "-a", "-nob", "-c=0", "-d=1", "-e=false", "-f=true"};
     std::string error;
+    LOCK(testArgs.cs_args);
     testArgs.SetupArgs({a, b, c, d, e, f});
     BOOST_CHECK(testArgs.ParseParameters(7, (char**)argv_test, error));
 
@@ -306,8 +308,8 @@ BOOST_AUTO_TEST_CASE(util_GetBoolArg)
         BOOST_CHECK(testArgs.IsArgSet({'-', opt}) || !opt);
 
     // Nothing else should be in the map
-    BOOST_CHECK(testArgs.GetOverrideArgs().size() == 6 &&
-                testArgs.GetConfigArgs().empty());
+    BOOST_CHECK(testArgs.m_settings.command_line_options.size() == 6 &&
+                testArgs.m_settings.ro_config.empty());
 
     // The -no prefix should get stripped on the way in.
     BOOST_CHECK(!testArgs.IsArgSet("-nob"));
@@ -403,6 +405,7 @@ BOOST_AUTO_TEST_CASE(util_ReadConfigStream)
        "iii=2\n";
 
     TestArgsManager test_args;
+    LOCK(test_args.cs_args);
     const auto a = std::make_pair("-a", ArgsManager::ALLOW_BOOL);
     const auto b = std::make_pair("-b", ArgsManager::ALLOW_BOOL);
     const auto ccc = std::make_pair("-ccc", ArgsManager::ALLOW_STRING);
@@ -419,22 +422,25 @@ BOOST_AUTO_TEST_CASE(util_ReadConfigStream)
     // expectation: a, b, ccc, d, fff, ggg, h, i end up in map
     // so do sec1.ccc, sec1.d, sec1.h, sec2.ccc, sec2.iii
 
-    BOOST_CHECK(test_args.GetOverrideArgs().empty());
-    BOOST_CHECK(test_args.GetConfigArgs().size() == 13);
-
-    BOOST_CHECK(test_args.GetConfigArgs().count("-a")
-                && test_args.GetConfigArgs().count("-b")
-                && test_args.GetConfigArgs().count("-ccc")
-                && test_args.GetConfigArgs().count("-d")
-                && test_args.GetConfigArgs().count("-fff")
-                && test_args.GetConfigArgs().count("-ggg")
-                && test_args.GetConfigArgs().count("-h")
-                && test_args.GetConfigArgs().count("-i")
+    BOOST_CHECK(test_args.m_settings.command_line_options.empty());
+    BOOST_CHECK(test_args.m_settings.ro_config.size() == 3);
+    BOOST_CHECK(test_args.m_settings.ro_config[""].size() == 8);
+    BOOST_CHECK(test_args.m_settings.ro_config["sec1"].size() == 3);
+    BOOST_CHECK(test_args.m_settings.ro_config["sec2"].size() == 2);
+
+    BOOST_CHECK(test_args.m_settings.ro_config[""].count("a")
+                && test_args.m_settings.ro_config[""].count("b")
+                && test_args.m_settings.ro_config[""].count("ccc")
+                && test_args.m_settings.ro_config[""].count("d")
+                && test_args.m_settings.ro_config[""].count("fff")
+                && test_args.m_settings.ro_config[""].count("ggg")
+                && test_args.m_settings.ro_config[""].count("h")
+                && test_args.m_settings.ro_config[""].count("i")
                );
-    BOOST_CHECK(test_args.GetConfigArgs().count("-sec1.ccc")
-                && test_args.GetConfigArgs().count("-sec1.h")
-                && test_args.GetConfigArgs().count("-sec2.ccc")
-                && test_args.GetConfigArgs().count("-sec2.iii")
+    BOOST_CHECK(test_args.m_settings.ro_config["sec1"].count("ccc")
+                && test_args.m_settings.ro_config["sec1"].count("h")
+                && test_args.m_settings.ro_config["sec2"].count("ccc")
+                && test_args.m_settings.ro_config["sec2"].count("iii")
                );
 
     BOOST_CHECK(test_args.IsArgSet("-a")
@@ -573,24 +579,25 @@ BOOST_AUTO_TEST_CASE(util_ReadConfigStream)
 BOOST_AUTO_TEST_CASE(util_GetArg)
 {
     TestArgsManager testArgs;
-    testArgs.GetOverrideArgs().clear();
-    testArgs.GetOverrideArgs()["strtest1"] = {"string..."};
+    LOCK(testArgs.cs_args);
+    testArgs.m_settings.command_line_options.clear();
+    testArgs.m_settings.command_line_options["strtest1"] = {"string..."};
     // strtest2 undefined on purpose
-    testArgs.GetOverrideArgs()["inttest1"] = {"12345"};
-    testArgs.GetOverrideArgs()["inttest2"] = {"81985529216486895"};
+    testArgs.m_settings.command_line_options["inttest1"] = {"12345"};
+    testArgs.m_settings.command_line_options["inttest2"] = {"81985529216486895"};
     // inttest3 undefined on purpose
-    testArgs.GetOverrideArgs()["booltest1"] = {""};
+    testArgs.m_settings.command_line_options["booltest1"] = {""};
     // booltest2 undefined on purpose
-    testArgs.GetOverrideArgs()["booltest3"] = {"0"};
-    testArgs.GetOverrideArgs()["booltest4"] = {"1"};
+    testArgs.m_settings.command_line_options["booltest3"] = {"0"};
+    testArgs.m_settings.command_line_options["booltest4"] = {"1"};
 
     // priorities
-    testArgs.GetOverrideArgs()["pritest1"] = {"a", "b"};
-    testArgs.GetConfigArgs()["pritest2"] = {"a", "b"};
-    testArgs.GetOverrideArgs()["pritest3"] = {"a"};
-    testArgs.GetConfigArgs()["pritest3"] = {"b"};
-    testArgs.GetOverrideArgs()["pritest4"] = {"a","b"};
-    testArgs.GetConfigArgs()["pritest4"] = {"c","d"};
+    testArgs.m_settings.command_line_options["pritest1"] = {"a", "b"};
+    testArgs.m_settings.ro_config[""]["pritest2"] = {"a", "b"};
+    testArgs.m_settings.command_line_options["pritest3"] = {"a"};
+    testArgs.m_settings.ro_config[""]["pritest3"] = {"b"};
+    testArgs.m_settings.command_line_options["pritest4"] = {"a","b"};
+    testArgs.m_settings.ro_config[""]["pritest4"] = {"c","d"};
 
     BOOST_CHECK_EQUAL(testArgs.GetArg("strtest1", "default"), "string...");
     BOOST_CHECK_EQUAL(testArgs.GetArg("strtest2", "default"), "default");
diff --git a/src/util/system.cpp b/src/util/system.cpp
index ed56e73960..2a2ae6fdf5 100644
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -63,6 +63,7 @@
 #endif
 
 #include <thread>
+#include <univalue.h>
 
 // Application startup time (used for uptime calculation)
 const int64_t nStartupTime = GetTime();
@@ -161,11 +162,14 @@ static bool InterpretBool(const std::string& strValue)
     return (atoi(strValue) != 0);
 }
 
+static std::string SettingName(const std::string& arg)
+{
+    return arg.size() > 0 && arg[0] == '-' ? arg.substr(1) : arg;
+}
+
 /** Internal helper functions for ArgsManager */
 class ArgsManagerHelper {
 public:
-    typedef std::map<std::string, std::vector<std::string>> MapArgs;
-
     /** Determine whether to use config settings in the default section,
      *  See also comments around ArgsManager::ArgsManager() below. */
     static inline bool UseDefaultSection(const ArgsManager& am, const std::string& arg) EXCLUSIVE_LOCKS_REQUIRED(am.cs_args)
@@ -173,91 +177,10 @@ public:
         return (am.m_network == CBaseChainParams::MAIN || am.m_network_only_args.count(arg) == 0);
     }
 
-    /** Convert regular argument into the network-specific setting */
-    static inline std::string NetworkArg(const ArgsManager& am, const std::string& arg)
-    {
-        assert(arg.length() > 1 && arg[0] == '-');
-        return "-" + am.m_network + "." + arg.substr(1);
-    }
-
-    /** Find arguments in a map and add them to a vector */
-    static inline void AddArgs(std::vector<std::string>& res, const MapArgs& map_args, const std::string& arg)
-    {
-        auto it = map_args.find(arg);
-        if (it != map_args.end()) {
-            res.insert(res.end(), it->second.begin(), it->second.end());
-        }
-    }
-
-    /** Return true/false if an argument is set in a map, and also
-     *  return the first (or last) of the possibly multiple values it has
-     */
-    static inline std::pair<bool,std::string> GetArgHelper(const MapArgs& map_args, const std::string& arg, bool getLast = false)
-    {
-        auto it = map_args.find(arg);
-
-        if (it == map_args.end() || it->second.empty()) {
-            return std::make_pair(false, std::string());
-        }
-
-        if (getLast) {
-            return std::make_pair(true, it->second.back());
-        } else {
-            return std::make_pair(true, it->second.front());
-        }
-    }
-
-    /* Get the string value of an argument, returning a pair of a boolean
-     * indicating the argument was found, and the value for the argument
-     * if it was found (or the empty string if not found).
-     */
-    static inline std::pair<bool,std::string> GetArg(const ArgsManager &am, const std::string& arg)
+    static util::SettingsValue Get(const ArgsManager& am, const std::string& arg)
     {
         LOCK(am.cs_args);
-        std::pair<bool,std::string> found_result(false, std::string());
-
-        // We pass "true" to GetArgHelper in order to return the last
-        // argument value seen from the command line (so "bitcoind -foo=bar
-        // -foo=baz" gives GetArg(am,"foo")=={true,"baz"}
-        found_result = GetArgHelper(am.m_override_args, arg, true);
-        if (found_result.first) {
-            return found_result;
-        }
-
-        // But in contrast we return the first argument seen in a config file,
-        // so "foo=bar \n foo=baz" in the config file gives
-        // GetArg(am,"foo")={true,"bar"}
-        if (!am.m_network.empty()) {
-            found_result = GetArgHelper(am.m_config_args, NetworkArg(am, arg));
-            if (found_result.first) {
-                return found_result;
-            }
-        }
-
-        if (UseDefaultSection(am, arg)) {
-            found_result = GetArgHelper(am.m_config_args, arg);
-            if (found_result.first) {
-                return found_result;
-            }
-        }
-
-        return found_result;
-    }
-
-    /* Special test for -testnet and -regtest args, because we
-     * don't want to be confused by craziness like "[regtest] testnet=1"
-     */
-    static inline bool GetNetBoolArg(const ArgsManager &am, const std::string& net_arg) EXCLUSIVE_LOCKS_REQUIRED(am.cs_args)
-    {
-        std::pair<bool,std::string> found_result(false,std::string());
-        found_result = GetArgHelper(am.m_override_args, net_arg, true);
-        if (!found_result.first) {
-            found_result = GetArgHelper(am.m_config_args, net_arg, true);
-            if (!found_result.first) {
-                return false; // not set
-            }
-        }
-        return InterpretBool(found_result.second); // is set, so evaluate
+        return GetSetting(am.m_settings, am.m_network, SettingName(arg), !UseDefaultSection(am, arg), /* get_chain_name= */ false);
     }
 };
 
@@ -268,13 +191,12 @@ public:
  * checks whether there was a double-negative (-nofoo=0 -> -foo=1).
  *
  * If there was not a double negative, it removes the "no" from the key
- * and clears the args vector to indicate a negated option.
+ * and returns false.
  *
- * If there was a double negative, it removes "no" from the key, sets the
- * value to "1" and pushes the key and the updated value to the args vector.
+ * If there was a double negative, it removes "no" from the key, and
+ * returns true.
  *
- * If there was no "no", it leaves key and value untouched and pushes them
- * to the args vector.
+ * If there was no "no", it returns the string value untouched.
  *
  * Where an option was negated can be later checked using the
  * IsArgNegated() method. One use case for this is to have a way to disable
@@ -282,34 +204,39 @@ public:
  * that debug log output is not sent to any file at all).
  */
 
-NODISCARD static bool InterpretOption(std::string key, std::string val, unsigned int flags,
-                                      std::map<std::string, std::vector<std::string>>& args,
-                                      std::string& error)
+static util::SettingsValue InterpretOption(std::string& section, std::string& key, const std::string& value)
 {
-    assert(key[0] == '-');
-
+    // Split section name from key name for keys like "testnet.foo" or "regtest.bar"
     size_t option_index = key.find('.');
-    if (option_index == std::string::npos) {
-        option_index = 1;
-    } else {
-        ++option_index;
+    if (option_index != std::string::npos) {
+        section = key.substr(0, option_index);
+        key.erase(0, option_index + 1);
     }
-    if (key.substr(option_index, 2) == "no") {
-        key.erase(option_index, 2);
-        if (flags & ArgsManager::ALLOW_BOOL) {
-            if (InterpretBool(val)) {
-                args[key].clear();
-                return true;
-            }
-            // Double negatives like -nofoo=0 are supported (but discouraged)
-            LogPrintf("Warning: parsed potentially confusing double-negative %s=%s\n", key, val);
-            val = "1";
-        } else {
-            error = strprintf("Negating of %s is meaningless and therefore forbidden", key);
-            return false;
+    if (key.substr(0, 2) == "no") {
+        key.erase(0, 2);
+        // Double negatives like -nofoo=0 are supported (but discouraged)
+        if (!InterpretBool(value)) {
+            LogPrintf("Warning: parsed potentially confusing double-negative -%s=%s\n", key, value);
+            return true;
         }
+        return false;
+    }
+    return value;
+}
+
+/**
+ * Check settings value validity according to flags.
+ *
+ * TODO: Add more meaningful error checks here in the future
+ * See "here's how the flags are meant to behave" in
+ * https://github.com/bitcoin/bitcoin/pull/16097#issuecomment-514627823
+ */
+static bool CheckValid(const std::string& key, const util::SettingsValue& val, unsigned int flags, std::string& error)
+{
+    if (val.isBool() && !(flags & ArgsManager::ALLOW_BOOL)) {
+        error = strprintf("Negating of -%s is meaningless and therefore forbidden", key);
+        return false;
     }
-    args[key].push_back(val);
     return true;
 }
 
@@ -331,22 +258,9 @@ const std::set<std::string> ArgsManager::GetUnsuitableSectionOnlyArgs() const
     if (m_network == CBaseChainParams::MAIN) return std::set<std::string> {};
 
     for (const auto& arg : m_network_only_args) {
-        std::pair<bool, std::string> found_result;
-
-        // if this option is overridden it's fine
-        found_result = ArgsManagerHelper::GetArgHelper(m_override_args, arg);
-        if (found_result.first) continue;
-
-        // if there's a network-specific value for this option, it's fine
-        found_result = ArgsManagerHelper::GetArgHelper(m_config_args, ArgsManagerHelper::NetworkArg(*this, arg));
-        if (found_result.first) continue;
-
-        // if there isn't a default value for this option, it's fine
-        found_result = ArgsManagerHelper::GetArgHelper(m_config_args, arg);
-        if (!found_result.first) continue;
-
-        // otherwise, issue a warning
-        unsuitables.insert(arg);
+        if (OnlyHasDefaultSectionSetting(m_settings, m_network, SettingName(arg))) {
+            unsuitables.insert(arg);
+        }
     }
     return unsuitables;
 }
@@ -375,7 +289,7 @@ void ArgsManager::SelectConfigNetwork(const std::string& network)
 bool ArgsManager::ParseParameters(int argc, const char* const argv[], std::string& error)
 {
     LOCK(cs_args);
-    m_override_args.clear();
+    m_settings.command_line_options.clear();
 
     for (int i = 1; i < argc; i++) {
         std::string key(argv[i]);
@@ -408,49 +322,44 @@ bool ArgsManager::ParseParameters(int argc, const char* const argv[], std::strin
         if (key.length() > 1 && key[1] == '-')
             key.erase(0, 1);
 
+        // Transform -foo to foo
+        key.erase(0, 1);
+        std::string section;
+        util::SettingsValue value = InterpretOption(section, key, val);
         const unsigned int flags = FlagsOfKnownArg(key);
         if (flags) {
-            if (!InterpretOption(key, val, flags, m_override_args, error)) {
+            if (!CheckValid(key, value, flags, error)) {
                 return false;
             }
+            // Weird behavior preserved for backwards compatibility: command
+            // line options with section prefixes are allowed but ignored. It
+            // would be better if these options triggered the Invalid parameter
+            // error below.
+            if (section.empty()) {
+                m_settings.command_line_options[key].push_back(value);
+            }
         } else {
-            error = strprintf("Invalid parameter %s", key);
+            error = strprintf("Invalid parameter -%s", key);
             return false;
         }
     }
 
     // we do not allow -includeconf from command line, so we clear it here
-    auto it = m_override_args.find("-includeconf");
-    if (it != m_override_args.end()) {
-        if (it->second.size() > 0) {
-            for (const auto& ic : it->second) {
-                error += "-includeconf cannot be used from commandline; -includeconf=" + ic + "\n";
-            }
-            return false;
+    bool success = true;
+    if (auto* includes = util::FindKey(m_settings.command_line_options, "includeconf")) {
+        for (const auto& include : util::SettingsSpan(*includes)) {
+            error += "-includeconf cannot be used from commandline; -includeconf=" + include.get_str() + "\n";
+            success = false;
         }
     }
-    return true;
+    return success;
 }
 
 unsigned int ArgsManager::FlagsOfKnownArg(const std::string& key) const
 {
-    assert(key[0] == '-');
-
-    size_t option_index = key.find('.');
-    if (option_index == std::string::npos) {
-        option_index = 1;
-    } else {
-        ++option_index;
-    }
-    if (key.substr(option_index, 2) == "no") {
-        option_index += 2;
-    }
-
-    const std::string base_arg_name = '-' + key.substr(option_index);
-
     LOCK(cs_args);
     for (const auto& arg_map : m_available_args) {
-        const auto search = arg_map.second.find(base_arg_name);
+        const auto search = arg_map.second.find('-' + key);
         if (search != arg_map.second.end()) {
             return search->second.m_flags;
         }
@@ -460,69 +369,42 @@ unsigned int ArgsManager::FlagsOfKnownArg(const std::string& key) const
 
 std::vector<std::string> ArgsManager::GetArgs(const std::string& strArg) const
 {
-    std::vector<std::string> result = {};
-    if (IsArgNegated(strArg)) return result; // special case
-
     LOCK(cs_args);
-
-    ArgsManagerHelper::AddArgs(result, m_override_args, strArg);
-    if (!m_network.empty()) {
-        ArgsManagerHelper::AddArgs(result, m_config_args, ArgsManagerHelper::NetworkArg(*this, strArg));
-    }
-
-    if (ArgsManagerHelper::UseDefaultSection(*this, strArg)) {
-        ArgsManagerHelper::AddArgs(result, m_config_args, strArg);
+    bool ignore_default_section_config = !ArgsManagerHelper::UseDefaultSection(*this, strArg);
+    std::vector<std::string> result;
+    for (const util::SettingsValue& value :
+        util::GetSettingsList(m_settings, m_network, SettingName(strArg), ignore_default_section_config)) {
+        result.push_back(value.isFalse() ? "0" : value.isTrue() ? "1" : value.get_str());
     }
-
     return result;
 }
 
 bool ArgsManager::IsArgSet(const std::string& strArg) const
 {
-    if (IsArgNegated(strArg)) return true; // special case
-    return ArgsManagerHelper::GetArg(*this, strArg).first;
+    return !ArgsManagerHelper::Get(*this, strArg).isNull();
 }
 
 bool ArgsManager::IsArgNegated(const std::string& strArg) const
 {
-    LOCK(cs_args);
-
-    const auto& ov = m_override_args.find(strArg);
-    if (ov != m_override_args.end()) return ov->second.empty();
-
-    if (!m_network.empty()) {
-        const auto& cfs = m_config_args.find(ArgsManagerHelper::NetworkArg(*this, strArg));
-        if (cfs != m_config_args.end()) return cfs->second.empty();
-    }
-
-    const auto& cf = m_config_args.find(strArg);
-    if (cf != m_config_args.end()) return cf->second.empty();
-
-    return false;
+    return ArgsManagerHelper::Get(*this, strArg).isFalse();
 }
 
 std::string ArgsManager::GetArg(const std::string& strArg, const std::string& strDefault) const
 {
-    if (IsArgNegated(strArg)) return "0";
-    std::pair<bool,std::string> found_res = ArgsManagerHelper::GetArg(*this, strArg);
-    if (found_res.first) return found_res.second;
-    return strDefault;
+    const util::SettingsValue value = ArgsManagerHelper::Get(*this, strArg);
+    return value.isNull() ? strDefault : value.isFalse() ? "0" : value.isTrue() ? "1" : value.get_str();
 }
 
 int64_t ArgsManager::GetArg(const std::string& strArg, int64_t nDefault) const
 {
-    if (IsArgNegated(strArg)) return 0;
-    std::pair<bool,std::string> found_res = ArgsManagerHelper::GetArg(*this, strArg);
-    if (found_res.first) return atoi64(found_res.second);
-    return nDefault;
+    const util::SettingsValue value = ArgsManagerHelper::Get(*this, strArg);
+    return value.isNull() ? nDefault : value.isFalse() ? 0 : value.isTrue() ? 1 : value.isNum() ? value.get_int64() : atoi64(value.get_str());
 }
 
 bool ArgsManager::GetBoolArg(const std::string& strArg, bool fDefault) const
 {
-    if (IsArgNegated(strArg)) return false;
-    std::pair<bool,std::string> found_res = ArgsManagerHelper::GetArg(*this, strArg);
-    if (found_res.first) return InterpretBool(found_res.second);
-    return fDefault;
+    const util::SettingsValue value = ArgsManagerHelper::Get(*this, strArg);
+    return value.isNull() ? fDefault : value.isBool() ? value.get_bool() : InterpretBool(value.get_str());
 }
 
 bool ArgsManager::SoftSetArg(const std::string& strArg, const std::string& strValue)
@@ -544,7 +426,7 @@ bool ArgsManager::SoftSetBoolArg(const std::string& strArg, bool fValue)
 void ArgsManager::ForceSetArg(const std::string& strArg, const std::string& strValue)
 {
     LOCK(cs_args);
-    m_override_args[strArg] = {strValue};
+    m_settings.forced_settings[SettingName(strArg)] = strValue;
 }
 
 void ArgsManager::AddArg(const std::string& name, const std::string& help, unsigned int flags, const OptionsCategory& cat)
@@ -860,12 +742,15 @@ bool ArgsManager::ReadConfigStream(std::istream& stream, const std::string& file
         return false;
     }
     for (const std::pair<std::string, std::string>& option : options) {
-        const std::string strKey = std::string("-") + option.first;
-        const unsigned int flags = FlagsOfKnownArg(strKey);
+        std::string section;
+        std::string key = option.first;
+        util::SettingsValue value = InterpretOption(section, key, option.second);
+        const unsigned int flags = FlagsOfKnownArg(key);
         if (flags) {
-            if (!InterpretOption(strKey, option.second, flags, m_config_args, error)) {
+            if (!CheckValid(key, value, flags, error)) {
                 return false;
             }
+            m_settings.ro_config[section][key].push_back(value);
         } else {
             if (ignore_invalid_keys) {
                 LogPrintf("Ignoring unknown configuration value %s\n", option.first);
@@ -882,7 +767,7 @@ bool ArgsManager::ReadConfigFiles(std::string& error, bool ignore_invalid_keys)
 {
     {
         LOCK(cs_args);
-        m_config_args.clear();
+        m_settings.ro_config.clear();
         m_config_sections.clear();
     }
 
@@ -899,30 +784,34 @@ bool ArgsManager::ReadConfigFiles(std::string& error, bool ignore_invalid_keys)
         bool use_conf_file{true};
         {
             LOCK(cs_args);
-            auto it = m_override_args.find("-includeconf");
-            if (it != m_override_args.end()) {
+            if (auto* includes = util::FindKey(m_settings.command_line_options, "includeconf")) {
                 // ParseParameters() fails if a non-negated -includeconf is passed on the command-line
-                assert(it->second.empty());
+                assert(util::SettingsSpan(*includes).last_negated());
                 use_conf_file = false;
             }
         }
         if (use_conf_file) {
             std::string chain_id = GetChainName();
-            std::vector<std::string> conf_file_names(GetArgs("-includeconf"));
-            {
-                // We haven't set m_network yet (that happens in SelectParams()), so manually check
-                // for network.includeconf args.
-                std::vector<std::string> includeconf_net(GetArgs(std::string("-") + chain_id + ".includeconf"));
-                conf_file_names.insert(conf_file_names.end(), includeconf_net.begin(), includeconf_net.end());
-            }
+            std::vector<std::string> conf_file_names;
 
-            // Remove -includeconf from configuration, so we can warn about recursion
-            // later
-            {
+            auto add_includes = [&](const std::string& network, size_t skip = 0) {
+                size_t num_values = 0;
                 LOCK(cs_args);
-                m_config_args.erase("-includeconf");
-                m_config_args.erase(std::string("-") + chain_id + ".includeconf");
-            }
+                if (auto* section = util::FindKey(m_settings.ro_config, network)) {
+                    if (auto* values = util::FindKey(*section, "includeconf")) {
+                        for (size_t i = std::max(skip, util::SettingsSpan(*values).negated()); i < values->size(); ++i) {
+                            conf_file_names.push_back((*values)[i].get_str());
+                        }
+                        num_values = values->size();
+                    }
+                }
+                return num_values;
+            };
+
+            // We haven't set m_network yet (that happens in SelectParams()), so manually check
+            // for network.includeconf args.
+            const size_t chain_includes = add_includes(chain_id);
+            const size_t default_includes = add_includes({});
 
             for (const std::string& conf_file_name : conf_file_names) {
                 fsbridge::ifstream conf_file_stream(GetConfigFile(conf_file_name));
@@ -938,14 +827,13 @@ bool ArgsManager::ReadConfigFiles(std::string& error, bool ignore_invalid_keys)
             }
 
             // Warn about recursive -includeconf
-            conf_file_names = GetArgs("-includeconf");
-            std::vector<std::string> includeconf_net(GetArgs(std::string("-") + chain_id + ".includeconf"));
-            conf_file_names.insert(conf_file_names.end(), includeconf_net.begin(), includeconf_net.end());
+            conf_file_names.clear();
+            add_includes(chain_id, /* skip= */ chain_includes);
+            add_includes({}, /* skip= */ default_includes);
             std::string chain_id_final = GetChainName();
             if (chain_id_final != chain_id) {
                 // Also warn about recursive includeconf for the chain that was specified in one of the includeconfs
-                includeconf_net = GetArgs(std::string("-") + chain_id_final + ".includeconf");
-                conf_file_names.insert(conf_file_names.end(), includeconf_net.begin(), includeconf_net.end());
+                add_includes(chain_id_final);
             }
             for (const std::string& conf_file_name : conf_file_names) {
                 tfm::format(std::cerr, "warning: -includeconf cannot be used from included files; ignoring -includeconf=%s\n", conf_file_name);
@@ -964,9 +852,16 @@ bool ArgsManager::ReadConfigFiles(std::string& error, bool ignore_invalid_keys)
 
 std::string ArgsManager::GetChainName() const
 {
-    LOCK(cs_args);
-    const bool fRegTest = ArgsManagerHelper::GetNetBoolArg(*this, "-regtest");
-    const bool fTestNet = ArgsManagerHelper::GetNetBoolArg(*this, "-testnet");
+    auto get_net = [&](const std::string& arg) {
+        LOCK(cs_args);
+        util::SettingsValue value = GetSetting(m_settings, /* section= */ "", SettingName(arg),
+                                               /* ignore_default_section_config= */ false,
+                                               /* get_chain_name= */ true);
+        return value.isNull() ? false : value.isBool() ? value.get_bool() : InterpretBool(value.get_str());
+    };
+
+    const bool fRegTest = get_net("-regtest");
+    const bool fTestNet = get_net("-testnet");
     const bool is_chain_arg_set = IsArgSet("-chain");
 
     if ((int)is_chain_arg_set + (int)fRegTest + (int)fTestNet > 1) {
diff --git a/src/util/system.h b/src/util/system.h
index 7452f186e6..e0b6371dc9 100644
--- a/src/util/system.h
+++ b/src/util/system.h
@@ -22,6 +22,7 @@
 #include <sync.h>
 #include <tinyformat.h>
 #include <util/memory.h>
+#include <util/settings.h>
 #include <util/threadnames.h>
 #include <util/time.h>
 
@@ -157,8 +158,7 @@ protected:
     };
 
     mutable CCriticalSection cs_args;
-    std::map<std::string, std::vector<std::string>> m_override_args GUARDED_BY(cs_args);
-    std::map<std::string, std::vector<std::string>> m_config_args GUARDED_BY(cs_args);
+    util::Settings m_settings GUARDED_BY(cs_args);
     std::string m_network GUARDED_BY(cs_args);
     std::set<std::string> m_network_only_args GUARDED_BY(cs_args);
     std::map<OptionsCategory, std::map<std::string, Arg>> m_available_args GUARDED_BY(cs_args);