bitcoin/src/util/settings.cpp
Russell Yanofsky 9c69cfe4c5 Add <datadir>/settings.json persistent settings storage.
Persistent settings are used in followup PRs  to unify gui settings
between bitcoin-qt and bitcoind, and  to add a load_on_startup flag to
the loadwallet RPC and maintain a dynamic list of wallets that should be loaded
on startup that also can be shared between bitcoind and bitcoin-qt.
2020-07-11 05:41:12 -04:00

240 lines
9.6 KiB
C++

// Copyright (c) 2019 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <util/settings.h>
#include <tinyformat.h>
#include <univalue.h>
namespace util {
namespace {
enum class Source {
FORCED,
COMMAND_LINE,
RW_SETTINGS,
CONFIG_FILE_NETWORK_SECTION,
CONFIG_FILE_DEFAULT_SECTION
};
//! Merge settings from multiple sources in precedence order:
//! Forced config > command line > read-write settings file > config file network-specific section > config file default section
//!
//! This function is provided with a callback function fn that contains
//! specific logic for how to merge the sources.
template <typename Fn>
static void MergeSettings(const Settings& settings, const std::string& section, const std::string& name, Fn&& fn)
{
// Merge in the forced settings
if (auto* value = FindKey(settings.forced_settings, name)) {
fn(SettingsSpan(*value), Source::FORCED);
}
// Merge in the command-line options
if (auto* values = FindKey(settings.command_line_options, name)) {
fn(SettingsSpan(*values), Source::COMMAND_LINE);
}
// Merge in the read-write settings
if (const SettingsValue* value = FindKey(settings.rw_settings, name)) {
fn(SettingsSpan(*value), Source::RW_SETTINGS);
}
// Merge in the network-specific section of the config file
if (!section.empty()) {
if (auto* map = FindKey(settings.ro_config, section)) {
if (auto* values = FindKey(*map, name)) {
fn(SettingsSpan(*values), Source::CONFIG_FILE_NETWORK_SECTION);
}
}
}
// Merge in the default section of the config file
if (auto* map = FindKey(settings.ro_config, "")) {
if (auto* values = FindKey(*map, name)) {
fn(SettingsSpan(*values), Source::CONFIG_FILE_DEFAULT_SECTION);
}
}
}
} // namespace
bool ReadSettings(const fs::path& path, std::map<std::string, SettingsValue>& values, std::vector<std::string>& errors)
{
values.clear();
errors.clear();
fsbridge::ifstream file;
file.open(path);
if (!file.is_open()) return true; // Ok for file not to exist.
SettingsValue in;
if (!in.read(std::string{std::istreambuf_iterator<char>(file), std::istreambuf_iterator<char>()})) {
errors.emplace_back(strprintf("Unable to parse settings file %s", path.string()));
return false;
}
if (file.fail()) {
errors.emplace_back(strprintf("Failed reading settings file %s", path.string()));
return false;
}
file.close(); // Done with file descriptor. Release while copying data.
if (!in.isObject()) {
errors.emplace_back(strprintf("Found non-object value %s in settings file %s", in.write(), path.string()));
return false;
}
const std::vector<std::string>& in_keys = in.getKeys();
const std::vector<SettingsValue>& in_values = in.getValues();
for (size_t i = 0; i < in_keys.size(); ++i) {
auto inserted = values.emplace(in_keys[i], in_values[i]);
if (!inserted.second) {
errors.emplace_back(strprintf("Found duplicate key %s in settings file %s", in_keys[i], path.string()));
}
}
return errors.empty();
}
bool WriteSettings(const fs::path& path,
const std::map<std::string, SettingsValue>& values,
std::vector<std::string>& errors)
{
SettingsValue out(SettingsValue::VOBJ);
for (const auto& value : values) {
out.__pushKV(value.first, value.second);
}
fsbridge::ofstream file;
file.open(path);
if (file.fail()) {
errors.emplace_back(strprintf("Error: Unable to open settings file %s for writing", path.string()));
return false;
}
file << out.write(/* prettyIndent= */ 1, /* indentLevel= */ 4) << std::endl;
file.close();
return true;
}
SettingsValue GetSetting(const Settings& settings,
const std::string& section,
const std::string& name,
bool ignore_default_section_config,
bool get_chain_name)
{
SettingsValue result;
bool done = false; // Done merging any more settings sources.
MergeSettings(settings, section, name, [&](SettingsSpan span, Source source) {
// Weird behavior preserved for backwards compatibility: Apply negated
// setting even if non-negated setting would be ignored. A negated
// value in the default section is applied to network specific options,
// even though normal non-negated values there would be ignored.
const bool never_ignore_negated_setting = span.last_negated();
// Weird behavior preserved for backwards compatibility: Take first
// assigned value instead of last. In general, later settings take
// precedence over early settings, but for backwards compatibility in
// the config file the precedence is reversed for all settings except
// chain name settings.
const bool reverse_precedence =
(source == Source::CONFIG_FILE_NETWORK_SECTION || source == Source::CONFIG_FILE_DEFAULT_SECTION) &&
!get_chain_name;
// Weird behavior preserved for backwards compatibility: Negated
// -regtest and -testnet arguments which you would expect to override
// values set in the configuration file are currently accepted but
// silently ignored. It would be better to apply these just like other
// negated values, or at least warn they are ignored.
const bool skip_negated_command_line = get_chain_name;
if (done) return;
// Ignore settings in default config section if requested.
if (ignore_default_section_config && source == Source::CONFIG_FILE_DEFAULT_SECTION &&
!never_ignore_negated_setting) {
return;
}
// Skip negated command line settings.
if (skip_negated_command_line && span.last_negated()) return;
if (!span.empty()) {
result = reverse_precedence ? span.begin()[0] : span.end()[-1];
done = true;
} else if (span.last_negated()) {
result = false;
done = true;
}
});
return result;
}
std::vector<SettingsValue> GetSettingsList(const Settings& settings,
const std::string& section,
const std::string& name,
bool ignore_default_section_config)
{
std::vector<SettingsValue> result;
bool done = false; // Done merging any more settings sources.
bool prev_negated_empty = false;
MergeSettings(settings, section, name, [&](SettingsSpan span, Source source) {
// Weird behavior preserved for backwards compatibility: Apply config
// file settings even if negated on command line. Negating a setting on
// command line will ignore earlier settings on the command line and
// ignore settings in the config file, unless the negated command line
// value is followed by non-negated value, in which case config file
// settings will be brought back from the dead (but earlier command
// line settings will still be ignored).
const bool add_zombie_config_values =
(source == Source::CONFIG_FILE_NETWORK_SECTION || source == Source::CONFIG_FILE_DEFAULT_SECTION) &&
!prev_negated_empty;
// Ignore settings in default config section if requested.
if (ignore_default_section_config && source == Source::CONFIG_FILE_DEFAULT_SECTION) return;
// Add new settings to the result if isn't already complete, or if the
// values are zombies.
if (!done || add_zombie_config_values) {
for (const auto& value : span) {
if (value.isArray()) {
result.insert(result.end(), value.getValues().begin(), value.getValues().end());
} else {
result.push_back(value);
}
}
}
// If a setting was negated, or if a setting was forced, set
// done to true to ignore any later lower priority settings.
done |= span.negated() > 0 || source == Source::FORCED;
// Update the negated and empty state used for the zombie values check.
prev_negated_empty |= span.last_negated() && result.empty();
});
return result;
}
bool OnlyHasDefaultSectionSetting(const Settings& settings, const std::string& section, const std::string& name)
{
bool has_default_section_setting = false;
bool has_other_setting = false;
MergeSettings(settings, section, name, [&](SettingsSpan span, Source source) {
if (span.empty()) return;
else if (source == Source::CONFIG_FILE_DEFAULT_SECTION) has_default_section_setting = true;
else has_other_setting = true;
});
// If a value is set in the default section and not explicitly overwritten by the
// user on the command line or in a different section, then we want to enable
// warnings about the value being ignored.
return has_default_section_setting && !has_other_setting;
}
SettingsSpan::SettingsSpan(const std::vector<SettingsValue>& vec) noexcept : SettingsSpan(vec.data(), vec.size()) {}
const SettingsValue* SettingsSpan::begin() const { return data + negated(); }
const SettingsValue* SettingsSpan::end() const { return data + size; }
bool SettingsSpan::empty() const { return size == 0 || last_negated(); }
bool SettingsSpan::last_negated() const { return size > 0 && data[size - 1].isFalse(); }
size_t SettingsSpan::negated() const
{
for (size_t i = size; i > 0; --i) {
if (data[i - 1].isFalse()) return i; // Return number of negated values (position of last false value)
}
return 0;
}
} // namespace util