Function get_setting

lib/dsc-lib/src/util.rs:112–160

Will search setting files for the specified setting. Performance implication: Use this function economically as every call opens/reads several config files. TODO: cache the config # Arguments `value_name` - The name of the setting. # Errors Will return `Err` if could not find requested setting.

(value_name: &str)

///
/// Will return `Err` if could not find requested setting.
pub fn get_setting(value_name: &str) -> Result<DscSettingValue, DscError> {

    const SETTINGS_FILE_NAME: &str = "dsc.settings.json";
    // Note that default settings file has root nodes as settings schema version that is specific to this version of dsc
    const DEFAULT_SETTINGS_FILE_NAME: &str = "dsc_default.settings.json";
    const DEFAULT_SETTINGS_SCHEMA_VERSION: &str = "1";

    let mut result: DscSettingValue = DscSettingValue::default();
    let mut settings_file_path : PathBuf;

    if let Some(exe_home) = get_exe_path()?.parent() {
        // First, get setting from the default settings file
        settings_file_path = exe_home.join(DEFAULT_SETTINGS_FILE_NAME);
        if let Ok(v) = load_value_from_json(&settings_file_path, DEFAULT_SETTINGS_SCHEMA_VERSION) {
            if let Some(n) = v.get(value_name) {
                result.setting = n.clone();
                debug!("{}", t!("util.foundSetting", name = value_name, path = settings_file_path.to_string_lossy()));
            }
        } else {
            debug!("{}", t!("util.notFoundSetting", name = value_name, path = settings_file_path.to_string_lossy()));
        }

        // Second, get setting from the active settings file overwriting previous value
        settings_file_path = exe_home.join(SETTINGS_FILE_NAME);
        if let Ok(v) = load_value_from_json(&settings_file_path, value_name) {
            result.setting = v;
            debug!("{}", t!("util.foundSetting", name = value_name, path = settings_file_path.to_string_lossy()));
        } else {
            debug!("{}", t!("util.notFoundSetting", name = value_name, path = settings_file_path.to_string_lossy()));
        }
    } else {
        debug!("{}", t!("util.failedToGetExePath"));
    }

    // Third, get setting from the policy
    settings_file_path = PathBuf::from(get_settings_policy_file_path());
    if let Ok(v) = load_value_from_json(&settings_file_path, value_name) {
        result.policy = v;
        debug!("{}", t!("util.foundSetting", name = value_name, path = settings_file_path.to_string_lossy()));
    } else {
        debug!("{}", t!("util.notFoundSetting", name = value_name, path = settings_file_path.to_string_lossy()));
    }

    if (result.setting == serde_json::Value::Null) && (result.policy == serde_json::Value::Null) {
        return Err(DscError::NotSupported(t!("util.settingNotFound", name = value_name).to_string()));
    }

    Ok(result)
}

fn load_value_from_json(path: &PathBuf, value_name: &str) -> Result<serde_json::Value, DscError> {
    let file = File::open(path)?;