jdk-24/test/jdk/javax/security/auth/Subject/CurrentSubject.java

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import javax.security.auth.Subject;
import java.security.AccessController;
import java.security.Principal;
import java.security.PrivilegedAction;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;

/*
 * @test
 * @bug 8267108
 * @summary confirm current subject specification
 * @run main/othervm CurrentSubject
 */
public class CurrentSubject {

    static transient boolean failed = false;
    static CountDownLatch cl = new CountDownLatch(1);
    static AtomicInteger count = new AtomicInteger();

    public static void main(String[] args) throws Exception {
        // At the beginning, current subject is null
        test("", null);
        cl.await();
        if (failed) {
            throw new Exception("Failed");
        }
    }

    /**
     * Ensure the current subject is the expected Subject object.
     *
     * @param label label to print out
     * @param expected the expected Subject
     */
    synchronized static void check(String label, Subject expected) {
        Subject cas = Subject.current();
        Subject accs = Subject.getSubject(AccessController.getContext());
        if (cas != accs) {
            failed = true;
            System.out.println(label + ": current " + s2s(cas)
                    + " but getSubject is " + s2s(accs));
        }
        Subject interested = cas;
        if (interested != expected) {
            failed = true;
            System.out.println(label + ": expected " + s2s(expected)
                    + " but see " + s2s(interested));
        } else {
            System.out.println(label + ": " + s2s(expected));
        }
    }

    /**
     * Recursively testing on current subject with getAs() and thread creations.
     *
     * @param name the current label
     * @param expected the expected Subject
     */
    static Void test(String name, Subject expected) {
        // Now it's the expected current subject
        check(" ".repeat(name.length()) + "-> " + name, expected);
        // Recursively check, do not go infinity
        if (name.length() < 4) {
            Subject another = new Subject();
            another.getPrincipals().add(new RawPrincipal(name + "d"));
            // run with a new subject, inside current subject will be the new subject
            Subject.callAs(another, () -> test(name + 'c', another));
            Subject.doAs(another, (PrivilegedAction<Void>) () -> test(name + 'd', another));
            // run with null, inside current subject will be null
            Subject.callAs(null, () -> test(name + 'C', null));
            Subject.doAs(null, (PrivilegedAction<Void>) () -> test(name + 'D', null));
            // new thread, inside current subject is unchanged
            count.incrementAndGet();
            new Thread(() -> {
                try {
                    test(name + 't', expected);
                    try {
                        Thread.sleep(500);
                    } catch (Exception e) {
                        throw new AssertionError(e);
                    }
                    // by this time, parent thread should have exited the
                    // action and current subject reset, but here
                    // current subject unchanged.
                    test(name + 'T', expected);
                } finally {
                    var n = count.decrementAndGet();
                    if (n == 0) {
                        cl.countDown();
                    }
                    assert n >= 0;
                }
            }).start();
        }
        // Now it's reset to original
        check(" ".repeat(name.length()) + "<- " + name, expected);
        return null;
    }

    static class RawPrincipal implements Principal {

        String name;
        RawPrincipal(String name) {
            this.name = name;
        }
        @Override
        public String getName() {
            return name;
        }
    }

    static String s2s(Subject s) {
        return s == null ? null
                : s.getPrincipals().iterator().next().getName();
    }
}