/* ProtectionDomain.java -- A security domain
   Copyright (C) 1998, 2003, Free Software Foundation, Inc.

This file is part of GNU Classpath.

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package java.security;

/**
 * <p>This <code>ProtectionDomain</code> class encapsulates the characteristics
 * of a domain, which encloses a set of classes whose instances are granted a
 * set of permissions when being executed on behalf of a given set of
 * <i>Principals</i>.
 *
 * <p>A static set of permissions can be bound to a <code>ProtectionDomain</code>
 * when it is constructed; such permissions are granted to the domain regardless
 * of the {@link Policy} in force. However, to support dynamic security
 * policies, a <code>ProtectionDomain</code> can also be constructed such that
 * it is dynamically mapped to a set of permissions by the current {@link
 * Policy} whenever a permission is checked.</p>
 *
 * @author Aaron M. Renn (arenn@urbanophile.com)
 * @version 0.0
 */
public class ProtectionDomain
{
  /** This is the <code>CodeSource</code> for this protection domain. */
  private CodeSource code_source;

  /** This is the set of permissions granted to this domain. */
  private PermissionCollection perms;

  /** The {@link ClassLoader} associated with this domain. */
  private ClassLoader classloader;

  /** The array of Principals associated with this domain.. */
  private Principal[] principals;

  /** Post 1.4 the policy may be refreshed! use false for pre 1.4. */
  private boolean staticBinding;

  /**
   * Creates a new <code>ProtectionDomain</code> with the given {@link
   * CodeSource} and {@link Permissions}. If the permissions object is not
   * <code>null</code>, then <code>setReadOnly()</code> will be called on the
   * passed in {@link Permissions} object. The only permissions granted to this
   * domain are the ones specified; the current {@link Policy} will not be
   * consulted.
   *
   * @param codesource the codesource associated with this domain.
   * @param permissions the permissions granted to this domain
   */
  public ProtectionDomain(CodeSource codesource, PermissionCollection permissions)
  {
    this(codesource, permissions, null, null, false);
  }

  /**
   * <p>Creates a new ProtectionDomain qualified by the given CodeSource,
   * Permissions, ClassLoader and array of Principals. If the permissions
   * object is not null, then <code>setReadOnly()</code> will be called on the
   * passed in Permissions object. The permissions granted to this domain are
   * dynamic; they include both the static permissions passed to this
   * constructor, and any permissions granted to this domain by the current
   * Policy at the time a permission is checked.</p>
   *
   * <p>This constructor is typically used by {@link ClassLoader}s and {@link
   * DomainCombiner}s which delegate to <code>Policy</code> to actively
   * associate the permissions granted to this domain. This constructor affords
   * the Policy provider the opportunity to augment the supplied
   * PermissionCollection to reflect policy changes.</p>
   *
   * @param codesource the CodeSource associated with this domain.
   * @param permissions the permissions granted to this domain.
   * @param classloader the ClassLoader associated with this domain.
   * @param principals the array of Principals associated with this domain.
   * @since 1.4
   * @see Policy#refresh()
   * @see Policy#getPermissions(ProtectionDomain)
  */
  public ProtectionDomain(CodeSource codesource,
                          PermissionCollection permissions,
                          ClassLoader classloader, Principal[] principals)
  {
    this(codesource, permissions, classloader, principals, false);
  }

  private ProtectionDomain(CodeSource codesource,
                           PermissionCollection permissions,
                           ClassLoader classloader, Principal[] principals,
                           boolean staticBinding)
  {
    super();

    code_source = codesource;
    if (permissions != null)
      {
        perms = permissions;
        perms.setReadOnly();
      }

    this.classloader = classloader;
    this.principals =
        (principals != null ? (Principal[]) principals.clone() : new Principal[0]);
    this.staticBinding = staticBinding;
  }

  /**
   * Returns the {@link CodeSource} of this domain.
   *
   * @return the {@link CodeSource} of this domain which may be <code>null</code>.
   * @since 1.2
   */
  public final CodeSource getCodeSource()
  {
    return code_source;
  }

  /**
   * Returns the {@link ClassLoader} of this domain.
   *
   * @return the {@link ClassLoader} of this domain which may be
   * <code>null</code>.
   * @since 1.4
   */
  public final ClassLoader getClassLoader()
  {
    return this.classloader;
  }

  /**
   * Returns an array of principals for this domain.
   *
   * @return returns a non-null array of principals for this domain. Changes to
   * this array will have no impact on the <code>ProtectionDomain</code>.
   * @since 1.4
   */
  public final Principal[] getPrincipals()
  {
    return (Principal[]) principals.clone();
  }

  /**
   * Returns the static permissions granted to this domain.
   *
   * @return the static set of permissions for this domain which may be
   * <code>null</code>.
   * @see Policy#refresh()
   * @see Policy#getPermissions(ProtectionDomain)
   */
  public final PermissionCollection getPermissions()
  {
    return perms;
  }

  /**
   * <p>Check and see if this <code>ProtectionDomain</code> implies the
   * permissions expressed in the <code>Permission</code> object.</p>
   *
   * <p>The set of permissions evaluated is a function of whether the
   * <code>ProtectionDomain</code> was constructed with a static set of
   * permissions or it was bound to a dynamically mapped set of permissions.</p>
   *
   * <p>If the <code>ProtectionDomain</code> was constructed to a statically
   * bound {@link PermissionCollection} then the permission will only be checked
   * against the {@link PermissionCollection} supplied at construction.</p>
   *
   * <p>However, if the <code>ProtectionDomain</code> was constructed with the
   * constructor variant which supports dynamically binding permissions, then
   * the permission will be checked against the combination of the
   * {@link PermissionCollection} supplied at construction and the current
   * {@link Policy} binding.
   *
   * @param permission the {@link Permission} object to check.
   * @return <code>true</code> if <code>permission</code> is implicit to this
   * <code>ProtectionDomain</code>.
   */
  public boolean implies(Permission permission)
  {
    if (staticBinding)
      return (perms == null ? false : perms.implies(permission));
    // Else dynamically bound.  Do we have it?
    // NOTE: this will force loading of Policy.currentPolicy
    return Policy.getCurrentPolicy().implies(this, permission);
  }

  /**
   * Convert a <code>ProtectionDomain</code> to a String.
   *
   * @return a string representation of the object.
   */
  public String toString()
  {
    String linesep = System.getProperty("line.separator");
    StringBuffer sb = new StringBuffer("ProtectionDomain (").append(linesep);

    if (code_source == null)
      sb.append("CodeSource:null");
    else
      sb.append(code_source);

    sb.append(linesep);
    if (classloader == null)
      sb.append("ClassLoader:null");
    else
      sb.append(classloader);

    sb.append(linesep);
    sb.append("Principals:");
    if (principals != null && principals.length > 0)
      {
        sb.append("[");
        Principal pal;
        for (int i = 0; i < principals.length; i++)
          {
            pal = principals[i];
            sb.append("'").append(pal.getName())
                .append("' of type ").append(pal.getClass().getName());
            if (i < principals.length-1)
              sb.append(", ");
          }
        sb.append("]");
      }
    else
      sb.append("none");

    sb.append(linesep);
    if (!staticBinding) // include all but dont force loading Policy.currentPolicy
      if (Policy.isLoaded())
        sb.append(Policy.getCurrentPolicy().getPermissions(this));
      else // fallback on this one's permissions
        sb.append(perms);
    else
      sb.append(perms);

    return sb.append(linesep).append(")").append(linesep).toString();
  }
}