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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package javax.security.auth;

import java.security.AccessController;
import java.security.Principal;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.util.Set;
import java.util.WeakHashMap;
import java.lang.ref.WeakReference;


A SubjectDomainCombiner updates ProtectionDomains with Principals from the Subject associated with this SubjectDomainCombiner. 
Since:1.4
/**
 * A {@code SubjectDomainCombiner} updates ProtectionDomains
 * with Principals from the {@code Subject} associated with this
 * {@code SubjectDomainCombiner}.
 *
 * @since 1.4
 */
public class SubjectDomainCombiner implements java.security.DomainCombiner {

    private Subject subject;
    private WeakKeyValueMap<ProtectionDomain, ProtectionDomain> cachedPDs =
                new WeakKeyValueMap<>();
    private Set<Principal> principalSet;
    private Principal[] principals;

    private static final sun.security.util.Debug debug =
        sun.security.util.Debug.getInstance("combiner",
                                        "\t[SubjectDomainCombiner]");

    
Associate the provided Subject with this SubjectDomainCombiner. 
Params:
  • subject – the Subject to be associated with this SubjectDomainCombiner.
/**
     * Associate the provided {@code Subject} with this
     * {@code SubjectDomainCombiner}.
     *
     * @param subject the {@code Subject} to be associated with
     *          this {@code SubjectDomainCombiner}.
     */
    public SubjectDomainCombiner(Subject subject) {
        this.subject = subject;

        if (subject.isReadOnly()) {
            principalSet = subject.getPrincipals();
            principals = principalSet.toArray
                        (new Principal[principalSet.size()]);
        }
    }

    
Get the Subject associated with this SubjectDomainCombiner. 
Throws:
  • SecurityException – if the caller does not have permission to get the Subject associated with this SubjectDomainCombiner.
Returns:the Subject associated with this SubjectDomainCombiner, or null if no Subject is associated with this SubjectDomainCombiner.
/**
     * Get the {@code Subject} associated with this
     * {@code SubjectDomainCombiner}.
     *
     * @return the {@code Subject} associated with this
     *          {@code SubjectDomainCombiner}, or {@code null}
     *          if no {@code Subject} is associated with this
     *          {@code SubjectDomainCombiner}.
     *
     * @exception SecurityException if the caller does not have permission
     *          to get the {@code Subject} associated with this
     *          {@code SubjectDomainCombiner}.
     */
    public Subject getSubject() {
        java.lang.SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(new AuthPermission
                ("getSubjectFromDomainCombiner"));
        }
        return subject;
    }

    
Update the relevant ProtectionDomains with the Principals from the Subject associated with this SubjectDomainCombiner. 
 A new ProtectionDomain instance is created for each non-static ProtectionDomain ( (staticPermissionsOnly() == false) in the currentDomains array. Each new ProtectionDomain instance is created using the CodeSource, Permissions and ClassLoader from the corresponding ProtectionDomain in currentDomains, as well as with the Principals from the Subject associated with this SubjectDomainCombiner. Static ProtectionDomains are combined as-is and no new instance is created. 
 All of the ProtectionDomains (static and newly instantiated) are combined into a new array. The ProtectionDomains from the assignedDomains array are appended to this new array, and the result is returned. 
 Note that optimizations such as the removal of duplicate
ProtectionDomains may have occurred.
In addition, caching of ProtectionDomains may be permitted.

Params:
  • currentDomains – the ProtectionDomains associated with the current execution Thread, up to the most recent privileged ProtectionDomain. The ProtectionDomains are listed in order of execution, with the most recently executing ProtectionDomain residing at the beginning of the array. This parameter may be null if the current execution Thread has no associated ProtectionDomains.
  • assignedDomains – the ProtectionDomains inherited from the parent Thread, or the ProtectionDomains from the privileged context, if a call to AccessController.doPrivileged(..., context) had occurred This parameter may be null if there were no ProtectionDomains inherited from the parent Thread, or from the privileged context.
Returns:a new array consisting of the updated ProtectionDomains, or null.
/**
     * Update the relevant ProtectionDomains with the Principals
     * from the {@code Subject} associated with this
     * {@code SubjectDomainCombiner}.
     *
     * <p> A new {@code ProtectionDomain} instance is created
     * for each non-static {@code ProtectionDomain} (
     * (staticPermissionsOnly() == false)
     * in the {@code currentDomains} array.  Each new {@code ProtectionDomain}
     * instance is created using the {@code CodeSource},
     * {@code Permission}s and {@code ClassLoader}
     * from the corresponding {@code ProtectionDomain} in
     * {@code currentDomains}, as well as with the Principals from
     * the {@code Subject} associated with this
     * {@code SubjectDomainCombiner}. Static ProtectionDomains are
     * combined as-is and no new instance is created.
     *
     * <p> All of the ProtectionDomains (static and newly instantiated) are
     * combined into a new array.  The ProtectionDomains from the
     * {@code assignedDomains} array are appended to this new array,
     * and the result is returned.
     *
     * <p> Note that optimizations such as the removal of duplicate
     * ProtectionDomains may have occurred.
     * In addition, caching of ProtectionDomains may be permitted.
     *
     * @param currentDomains the ProtectionDomains associated with the
     *          current execution Thread, up to the most recent
     *          privileged {@code ProtectionDomain}.
     *          The ProtectionDomains are listed in order of execution,
     *          with the most recently executing {@code ProtectionDomain}
     *          residing at the beginning of the array. This parameter may
     *          be {@code null} if the current execution Thread
     *          has no associated ProtectionDomains.
     *
     * @param assignedDomains the ProtectionDomains inherited from the
     *          parent Thread, or the ProtectionDomains from the
     *          privileged {@code context}, if a call to
     *          {@code AccessController.doPrivileged(..., context)}
     *          had occurred  This parameter may be {@code null}
     *          if there were no ProtectionDomains inherited from the
     *          parent Thread, or from the privileged {@code context}.
     *
     * @return a new array consisting of the updated ProtectionDomains,
     *          or {@code null}.
     */
    public ProtectionDomain[] combine(ProtectionDomain[] currentDomains,
                                ProtectionDomain[] assignedDomains) {
        if (debug != null) {
            if (subject == null) {
                debug.println("null subject");
            } else {
                final Subject s = subject;
                AccessController.doPrivileged
                    (new java.security.PrivilegedAction<Void>() {
                    public Void run() {
                        debug.println(s.toString());
                        return null;
                    }
                });
            }
            printInputDomains(currentDomains, assignedDomains);
        }

        if (currentDomains == null || currentDomains.length == 0) {
            // No need to optimize assignedDomains because it should
            // have been previously optimized (when it was set).

            // Note that we are returning a direct reference
            // to the input array - since ACC does not clone
            // the arrays when it calls combiner.combine,
            // multiple ACC instances may share the same
            // array instance in this case

            return assignedDomains;
        }

        // optimize currentDomains
        //
        // No need to optimize assignedDomains because it should
        // have been previously optimized (when it was set).

        currentDomains = optimize(currentDomains);
        if (debug != null) {
            debug.println("after optimize");
            printInputDomains(currentDomains, assignedDomains);
        }

        if (currentDomains == null && assignedDomains == null) {
            return null;
        }

        int cLen = (currentDomains == null ? 0 : currentDomains.length);
        int aLen = (assignedDomains == null ? 0 : assignedDomains.length);

        // the ProtectionDomains for the new AccessControlContext
        // that we will return
        ProtectionDomain[] newDomains = new ProtectionDomain[cLen + aLen];

        boolean allNew = true;
        synchronized(cachedPDs) {
            if (!subject.isReadOnly() &&
                !subject.getPrincipals().equals(principalSet)) {

                // if the Subject was mutated, clear the PD cache
                Set<Principal> newSet = subject.getPrincipals();
                synchronized(newSet) {
                    principalSet = new java.util.HashSet<Principal>(newSet);
                }
                principals = principalSet.toArray
                        (new Principal[principalSet.size()]);
                cachedPDs.clear();

                if (debug != null) {
                    debug.println("Subject mutated - clearing cache");
                }
            }

            ProtectionDomain subjectPd;
            for (int i = 0; i < cLen; i++) {
                ProtectionDomain pd = currentDomains[i];

                subjectPd = cachedPDs.getValue(pd);

                if (subjectPd == null) {
                    if (pd.staticPermissionsOnly()) {
                        // keep static ProtectionDomain objects static
                        subjectPd = pd;
                    } else {
                        subjectPd = new ProtectionDomain(pd.getCodeSource(),
                                                pd.getPermissions(),
                                                pd.getClassLoader(),
                                                principals);
                    }
                    cachedPDs.putValue(pd, subjectPd);
                } else {
                    allNew = false;
                }
                newDomains[i] = subjectPd;
            }
        }

        if (debug != null) {
            debug.println("updated current: ");
            for (int i = 0; i < cLen; i++) {
                debug.println("\tupdated[" + i + "] = " +
                                printDomain(newDomains[i]));
            }
        }

        // now add on the assigned domains
        if (aLen > 0) {
            System.arraycopy(assignedDomains, 0, newDomains, cLen, aLen);

            // optimize the result (cached PDs might exist in assignedDomains)
            if (!allNew) {
                newDomains = optimize(newDomains);
            }
        }

        // if aLen == 0 || allNew, no need to further optimize newDomains

        if (debug != null) {
            if (newDomains == null || newDomains.length == 0) {
                debug.println("returning null");
            } else {
                debug.println("combinedDomains: ");
                for (int i = 0; i < newDomains.length; i++) {
                    debug.println("newDomain " + i + ": " +
                                  printDomain(newDomains[i]));
                }
            }
        }

        // return the new ProtectionDomains
        if (newDomains == null || newDomains.length == 0) {
            return null;
        } else {
            return newDomains;
        }
    }

    private static ProtectionDomain[] optimize(ProtectionDomain[] domains) {
        if (domains == null || domains.length == 0)
            return null;

        ProtectionDomain[] optimized = new ProtectionDomain[domains.length];
        ProtectionDomain pd;
        int num = 0;
        for (int i = 0; i < domains.length; i++) {

            // skip domains with AllPermission
            // XXX
            //
            //  if (domains[i].implies(ALL_PERMISSION))
            //  continue;

            // skip System Domains
            if ((pd = domains[i]) != null) {

                // remove duplicates
                boolean found = false;
                for (int j = 0; j < num && !found; j++) {
                    found = (optimized[j] == pd);
                }
                if (!found) {
                    optimized[num++] = pd;
                }
            }
        }

        // resize the array if necessary
        if (num > 0 && num < domains.length) {
            ProtectionDomain[] downSize = new ProtectionDomain[num];
            System.arraycopy(optimized, 0, downSize, 0, downSize.length);
            optimized = downSize;
        }

        return ((num == 0 || optimized.length == 0) ? null : optimized);
    }

    private static void printInputDomains(ProtectionDomain[] currentDomains,
                                ProtectionDomain[] assignedDomains) {
        if (currentDomains == null || currentDomains.length == 0) {
            debug.println("currentDomains null or 0 length");
        } else {
            for (int i = 0; currentDomains != null &&
                        i < currentDomains.length; i++) {
                if (currentDomains[i] == null) {
                    debug.println("currentDomain " + i + ": SystemDomain");
                } else {
                    debug.println("currentDomain " + i + ": " +
                                printDomain(currentDomains[i]));
                }
            }
        }

        if (assignedDomains == null || assignedDomains.length == 0) {
            debug.println("assignedDomains null or 0 length");
        } else {
            debug.println("assignedDomains = ");
            for (int i = 0; assignedDomains != null &&
                        i < assignedDomains.length; i++) {
                if (assignedDomains[i] == null) {
                    debug.println("assignedDomain " + i + ": SystemDomain");
                } else {
                    debug.println("assignedDomain " + i + ": " +
                                printDomain(assignedDomains[i]));
                }
            }
        }
    }

    private static String printDomain(final ProtectionDomain pd) {
        if (pd == null) {
            return "null";
        }
        return AccessController.doPrivileged(new PrivilegedAction<String>() {
            public String run() {
                return pd.toString();
            }
        });
    }

    
A HashMap that has weak keys and values.
Key objects in this map are the "current" ProtectionDomain instances
received via the combine method.  Each "current" PD is mapped to a
new PD instance that holds both the contents of the "current" PD,
as well as the principals from the Subject associated with this combiner.
The newly created "principal-based" PD values must be stored as
WeakReferences since they contain strong references to the
corresponding key object (the "current" non-principal-based PD),
which will prevent the key from being GC'd.  Specifically,
a "principal-based" PD contains strong references to the CodeSource,
signer certs, PermissionCollection and ClassLoader objects
in the "current PD".

/**
     * A HashMap that has weak keys and values.
     *
     * Key objects in this map are the "current" ProtectionDomain instances
     * received via the combine method.  Each "current" PD is mapped to a
     * new PD instance that holds both the contents of the "current" PD,
     * as well as the principals from the Subject associated with this combiner.
     *
     * The newly created "principal-based" PD values must be stored as
     * WeakReferences since they contain strong references to the
     * corresponding key object (the "current" non-principal-based PD),
     * which will prevent the key from being GC'd.  Specifically,
     * a "principal-based" PD contains strong references to the CodeSource,
     * signer certs, PermissionCollection and ClassLoader objects
     * in the "current PD".
     */
    private static class WeakKeyValueMap<K,V> extends
                                        WeakHashMap<K,WeakReference<V>> {

        public V getValue(K key) {
            WeakReference<V> wr = super.get(key);
            if (wr != null) {
                return wr.get();
            }
            return null;
        }

        public V putValue(K key, V value) {
            WeakReference<V> wr = super.put(key, new WeakReference<V>(value));
            if (wr != null) {
                return wr.get();
            }
            return null;
        }
    }
}