    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019
    020package org.apache.commons.exec.environment;
    021
    022import java.io.IOException;
    023import java.util.Map;
    024import java.util.Objects;
    025
    026/**
    027 * Wraps environment variables.
    028 */
    029public class EnvironmentUtils {
    030
    031    /**
    032     * Default environment.
    033     */
    034    private static final DefaultProcessingEnvironment ENVIRONMENT;
    035
    036    static {
    037        ENVIRONMENT = new DefaultProcessingEnvironment();
    038    }
    039
    040    /**
    041     * Adds a key/value pair to the given environment. If the key matches an existing key, the previous setting is replaced.
    042     *
    043     * @param environment the current environment.
    044     * @param keyAndValue the key/value pair.
    045     */
    046    public static void addVariableToEnvironment(final Map<String, String> environment, final String keyAndValue) {
    047        final String[] parsedVariable = parseEnvironmentVariable(keyAndValue);
    048        environment.put(parsedVariable[0], parsedVariable[1]);
    049    }
    050
    051    /**
    052     * Gets the list of environment variables for this process. The returned map preserves the casing of a variable's name on all platforms but obeys the casing
    053     * rules of the current platform during lookup, e.g. key names will be case-insensitive on Windows platforms.
    054     *
    055     * @return a map containing the environment variables, may be empty but never {@code null}.
    056     * @throws IOException the operation failed.
    057     */
    058    public static Map<String, String> getProcEnvironment() throws IOException {
    059        return ENVIRONMENT.getProcEnvironment();
    060    }
    061
    062    /**
    063     * Parses a key/value pair into a String[]. It is assumed that the ky/value pair contains a '=' character.
    064     *
    065     * @param keyAndValue the key/value pair.
    066     * @return a String[] containing the key and value.
    067     */
    068    private static String[] parseEnvironmentVariable(final String keyAndValue) {
    069        final int index = keyAndValue.indexOf('=');
    070        if (index == -1) {
    071            throw new IllegalArgumentException("Environment variable for this platform must contain an equals sign ('=')");
    072        }
    073        final String[] result = new String[2];
    074        result[0] = keyAndValue.substring(0, index);
    075        result[1] = keyAndValue.substring(index + 1);
    076        return result;
    077    }
    078
    079    private static String toString(final String value) {
    080        return Objects.toString(value, "");
    081    }
    082
    083    /**
    084     * Converts a variable map as an array.
    085     *
    086     * @param environment the environment to use, may be {@code null}.
    087     * @return array of key=value assignment strings or {@code null} if and only if the input map was {@code null}.
    088     */
    089    public static String[] toStrings(final Map<String, String> environment) {
    090        if (environment == null) {
    091            return null;
    092        }
    093        return environment.entrySet().stream().map(e -> toString(e.getKey()) + "=" + toString(e.getValue())).toArray(String[]::new);
    094    }
    095
    096    /**
    097     * Hides constructor.
    098     */
    099    private EnvironmentUtils() {
    100        // empty
    101    }
    102
    103}