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/*
* Copyright 2016-2023 the original author or authors.
*
* All rights reserved. This program and the accompanying materials are
* made available under the terms of the Eclipse Public License v2.0 which
* accompanies this distribution and is available at
*
* http://www.eclipse.org/legal/epl-v20.html
*/
package org.junitpioneer.jupiter;
import java.lang.reflect.Field;
import java.lang.reflect.InaccessibleObjectException;
import java.util.Map;
import java.util.function.Consumer;
import org.junit.platform.commons.PreconditionViolationException;
/**
* This class modifies the internals of the environment variables map with reflection.
* Warning: If your {@link SecurityManager} does not allow modifications, it fails.
*/
class EnvironmentVariableUtils {
private EnvironmentVariableUtils() {
// private constructor to prevent instantiation of utility class
}
/**
* Set a value of an environment variable.
*
* @param name of the environment variable
* @param value of the environment variable
*/
public static void set(String name, String value) {
modifyEnvironmentVariables(map -> map.put(name, value));
}
/**
* Clear an environment variable.
*
* @param name of the environment variable
*/
public static void clear(String name) {
modifyEnvironmentVariables(map -> map.remove(name));
}
private static void modifyEnvironmentVariables(Consumer> consumer) {
try {
setInProcessEnvironmentClass(consumer);
}
catch (ReflectiveOperationException ex) {
trySystemEnvClass(consumer, ex);
}
}
private static void trySystemEnvClass(Consumer> consumer,
ReflectiveOperationException processEnvironmentClassEx) {
try {
setInSystemEnvClass(consumer);
}
catch (ReflectiveOperationException ex) {
ex.addSuppressed(processEnvironmentClassEx);
throw new PreconditionViolationException("Could not modify environment variables", ex);
}
}
/*
* Works on Windows
*/
private static void setInProcessEnvironmentClass(Consumer> consumer)
throws ReflectiveOperationException {
Class processEnvironmentClass = Class.forName("java.lang.ProcessEnvironment");
// The order of operations is critical here: On some operating systems, theEnvironment is present but
// theCaseInsensitiveEnvironment is not present. In such cases, this method must throw a
// ReflectiveOperationException without modifying theEnvironment. Otherwise, the contents of theEnvironment will
// be corrupted. For this reason, both fields are fetched by reflection before either field is modified.
Map theEnvironment = getFieldValue(processEnvironmentClass, null, "theEnvironment");
Map theCaseInsensitiveEnvironment = getFieldValue(processEnvironmentClass, null,
"theCaseInsensitiveEnvironment");
consumer.accept(theEnvironment);
consumer.accept(theCaseInsensitiveEnvironment);
}
/*
* Works on Linux and OSX
*/
private static void setInSystemEnvClass(Consumer> consumer)
throws ReflectiveOperationException {
Map env = System.getenv(); //NOSONAR access required to implement the extension
consumer.accept(getFieldValue(env.getClass(), env, "m"));
}
@SuppressWarnings("unchecked")
private static Map getFieldValue(Class clazz, Object object, String name)
throws ReflectiveOperationException {
Field field = clazz.getDeclaredField(name);
try {
field.setAccessible(true); //NOSONAR illegal access required to implement the extension
}
catch (InaccessibleObjectException ex) {
throw new PreconditionViolationException(
"Cannot access and modify JDK internals to modify environment variables. "
+ "Have a look at the documentation for possible solutions: "
+ "https://junit-pioneer.org/docs/environment-variables/#warnings-for-reflective-access",
ex);
}
return (Map) field.get(object);
}
}