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