/*
 * Copyright (c) OSGi Alliance (2000, 2012). All Rights Reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.osgi.framework;

import java.io.IOException;
import java.io.NotSerializableException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamField;
import java.security.AccessController;
import java.security.BasicPermission;
import java.security.Permission;
import java.security.PermissionCollection;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.List;
import java.util.Map;

/**
 * A bundle's authority to import or export a package.
 * 
 * <p>
 * A package is a dot-separated string that defines a fully qualified Java
 * package.
 * <p>
 * For example:
 * 
 * <pre>
 * org.osgi.service.http
 * </pre>
 * 
 * <p>
 * {@code PackagePermission} has three actions: {@code exportonly},
 * {@code import} and {@code export}. The {@code export} action, which is
 * deprecated, implies the {@code import} action.
 * 
 * @ThreadSafe
 * @version $Id: e993fbc36b6bff84182a8594af5af3cad8c4e2a3 $
 */

public final class PackagePermission extends BasicPermission {
	static final long								serialVersionUID	= -5107705877071099135L;

	/**
	 * The action string {@code export}. The {@code export} action implies the
	 * {@code import} action.
	 * 
	 * @deprecated Since 1.5. Use {@code exportonly} instead.
	 */
	public final static String						EXPORT				= "export";

	/**
	 * The action string {@code exportonly}. The {@code exportonly} action does
	 * not imply the {@code import} action.
	 * 
	 * @since 1.5
	 */
	public final static String						EXPORTONLY			= "exportonly";

	/**
	 * The action string {@code import}.
	 */
	public final static String						IMPORT				= "import";

	private final static int						ACTION_EXPORT		= 0x00000001;
	private final static int						ACTION_IMPORT		= 0x00000002;
	private final static int						ACTION_ALL			= ACTION_EXPORT | ACTION_IMPORT;
	final static int								ACTION_NONE			= 0;

	/**
	 * The actions mask.
	 */
	transient int									action_mask;

	/**
	 * The actions in canonical form.
	 * 
	 * @serial
	 */
	private volatile String							actions				= null;

	/**
	 * The bundle used by this PackagePermission.
	 */
	transient final Bundle							bundle;

	/**
	 * If this PackagePermission was constructed with a filter, this holds a
	 * Filter matching object used to evaluate the filter in implies.
	 */
	transient Filter								filter;

	/**
	 * This map holds the properties of the permission, used to match a filter
	 * in implies. This is not initialized until necessary, and then cached in
	 * this object.
	 */
	private transient volatile Map<String, Object>	properties;

	/**
	 * Creates a new {@code PackagePermission} object.
	 * 
	 * <p>
	 * The name is specified as a normal Java package name: a dot-separated
	 * string. Wildcards may be used.
	 * 
	 * <pre>
	 * name ::= &lt;package name&gt; | &lt;package name ending in &quot;.*&quot;&gt; | *
	 * </pre>
	 * 
	 * Examples:
	 * 
	 * <pre>
	 * org.osgi.service.http
	 * javax.servlet.*
	 * *
	 * </pre>
	 * 
	 * For the {@code import} action, the name can also be a filter expression.
	 * The filter gives access to the following attributes:
	 * <ul>
	 * <li>signer - A Distinguished Name chain used to sign the exporting
	 * bundle. Wildcards in a DN are not matched according to the filter string
	 * rules, but according to the rules defined for a DN chain.</li>
	 * <li>location - The location of the exporting bundle.</li>
	 * <li>id - The bundle ID of the exporting bundle.</li>
	 * <li>name - The symbolic name of the exporting bundle.</li>
	 * <li>package.name - The name of the requested package.</li>
	 * </ul>
	 * Filter attribute names are processed in a case sensitive manner.
	 * 
	 * <p>
	 * Package Permissions are granted over all possible versions of a package.
	 * 
	 * A bundle that needs to export a package must have the appropriate
	 * {@code PackagePermission} for that package; similarly, a bundle that
	 * needs to import a package must have the appropriate
	 * {@code PackagePermssion} for that package.
	 * <p>
	 * Permission is granted for both classes and resources.
	 * 
	 * @param name Package name or filter expression. A filter expression can
	 *        only be specified if the specified action is {@code import}.
	 * @param actions {@code exportonly},{@code import} (canonical order).
	 * @throws IllegalArgumentException If the specified name is a filter
	 *         expression and either the specified action is not {@code import}
	 *         or the filter has an invalid syntax.
	 */
	public PackagePermission(String name, String actions) {
		this(name, parseActions(actions));
		if ((filter != null) && ((action_mask & ACTION_ALL) != ACTION_IMPORT)) {
			throw new IllegalArgumentException("invalid action string for filter expression");
		}
	}

	/**
	 * Creates a new requested {@code PackagePermission} object to be used by
	 * code that must perform {@code checkPermission} for the {@code import}
	 * action. {@code PackagePermission} objects created with this constructor
	 * cannot be added to a {@code PackagePermission} permission collection.
	 * 
	 * @param name The name of the requested package to import.
	 * @param exportingBundle The bundle exporting the requested package.
	 * @param actions The action {@code import}.
	 * @throws IllegalArgumentException If the specified action is not
	 *         {@code import} or the name is a filter expression.
	 * @since 1.5
	 */
	public PackagePermission(String name, Bundle exportingBundle, String actions) {
		super(name);
		setTransients(name, parseActions(actions));
		this.bundle = exportingBundle;
		if (exportingBundle == null) {
			throw new IllegalArgumentException("bundle must not be null");
		}
		if (filter != null) {
			throw new IllegalArgumentException("invalid name");
		}
		if ((action_mask & ACTION_ALL) != ACTION_IMPORT) {
			throw new IllegalArgumentException("invalid action string");
		}
	}

	/**
	 * Package private constructor used by PackagePermissionCollection.
	 * 
	 * @param name package name
	 * @param mask action mask
	 */
	PackagePermission(String name, int mask) {
		super(name);
		setTransients(name, mask);
		this.bundle = null;
	}

	/**
	 * Called by constructors and when deserialized.
	 * 
	 * @param mask action mask
	 */
	private void setTransients(String name, int mask) {
		if ((mask == ACTION_NONE) || ((mask & ACTION_ALL) != mask)) {
			throw new IllegalArgumentException("invalid action string");
		}
		action_mask = mask;
		filter = parseFilter(name);
	}

	/**
	 * Parse action string into action mask.
	 * 
	 * @param actions Action string.
	 * @return action mask.
	 */
	private static int parseActions(String actions) {
		boolean seencomma = false;

		int mask = ACTION_NONE;

		if (actions == null) {
			return mask;
		}

		char[] a = actions.toCharArray();

		int i = a.length - 1;
		if (i < 0)
			return mask;

		while (i != -1) {
			char c;

			// skip whitespace
			while ((i != -1) && ((c = a[i]) == ' ' || c == '\r' || c == '\n' || c == '\f' || c == '\t'))
				i--;

			// check for the known strings
			int matchlen;

			if (i >= 5 && (a[i - 5] == 'i' || a[i - 5] == 'I')
					&& (a[i - 4] == 'm' || a[i - 4] == 'M')
					&& (a[i - 3] == 'p' || a[i - 3] == 'P')
					&& (a[i - 2] == 'o' || a[i - 2] == 'O')
					&& (a[i - 1] == 'r' || a[i - 1] == 'R')
					&& (a[i] == 't' || a[i] == 'T')) {
				matchlen = 6;
				mask |= ACTION_IMPORT;

			} else
				if (i >= 5 && (a[i - 5] == 'e' || a[i - 5] == 'E')
						&& (a[i - 4] == 'x' || a[i - 4] == 'X')
						&& (a[i - 3] == 'p' || a[i - 3] == 'P')
						&& (a[i - 2] == 'o' || a[i - 2] == 'O')
						&& (a[i - 1] == 'r' || a[i - 1] == 'R')
						&& (a[i] == 't' || a[i] == 'T')) {
					matchlen = 6;
					mask |= ACTION_EXPORT | ACTION_IMPORT;

				} else {
					if (i >= 9 && (a[i - 9] == 'e' || a[i - 9] == 'E')
							&& (a[i - 8] == 'x' || a[i - 8] == 'X')
							&& (a[i - 7] == 'p' || a[i - 7] == 'P')
							&& (a[i - 6] == 'o' || a[i - 6] == 'O')
							&& (a[i - 5] == 'r' || a[i - 5] == 'R')
							&& (a[i - 4] == 't' || a[i - 4] == 'T')
							&& (a[i - 3] == 'o' || a[i - 3] == 'O')
							&& (a[i - 2] == 'n' || a[i - 2] == 'N')
							&& (a[i - 1] == 'l' || a[i - 1] == 'L')
							&& (a[i] == 'y' || a[i] == 'Y')) {
						matchlen = 10;
						mask |= ACTION_EXPORT;

					} else {
						// parse error
						throw new IllegalArgumentException("invalid permission: " + actions);
					}
				}

			// make sure we didn't just match the tail of a word
			// like "ackbarfimport". Also, skip to the comma.
			seencomma = false;
			while (i >= matchlen && !seencomma) {
				switch (a[i - matchlen]) {
					case ',' :
						seencomma = true;
						/* FALLTHROUGH */
					case ' ' :
					case '\r' :
					case '\n' :
					case '\f' :
					case '\t' :
						break;
					default :
						throw new IllegalArgumentException("invalid permission: " + actions);
				}
				i--;
			}

			// point i at the location of the comma minus one (or -1).
			i -= matchlen;
		}

		if (seencomma) {
			throw new IllegalArgumentException("invalid permission: " + actions);
		}

		return mask;
	}

	/**
	 * Parse filter string into a Filter object.
	 * 
	 * @param filterString The filter string to parse.
	 * @return a Filter for this bundle. If the specified filterString is not a
	 *         filter expression, then {@code null} is returned.
	 * @throws IllegalArgumentException If the filter syntax is invalid.
	 */
	private static Filter parseFilter(String filterString) {
		filterString = filterString.trim();
		if (filterString.charAt(0) != '(') {
			return null;
		}

		try {
			return FrameworkUtil.createFilter(filterString);
		} catch (InvalidSyntaxException e) {
			IllegalArgumentException iae = new IllegalArgumentException("invalid filter");
			iae.initCause(e);
			throw iae;
		}
	}

	/**
	 * Determines if the specified permission is implied by this object.
	 * 
	 * <p>
	 * This method checks that the package name of the target is implied by the
	 * package name of this object. The list of {@code PackagePermission}
	 * actions must either match or allow for the list of the target object to
	 * imply the target {@code PackagePermission} action.
	 * <p>
	 * The permission to export a package implies the permission to import the
	 * named package.
	 * 
	 * <pre>
	 * x.y.*,&quot;export&quot; -&gt; x.y.z,&quot;export&quot; is true
	 * *,&quot;import&quot; -&gt; x.y, &quot;import&quot;      is true
	 * *,&quot;export&quot; -&gt; x.y, &quot;import&quot;      is true
	 * x.y,&quot;export&quot; -&gt; x.y.z, &quot;export&quot;  is false
	 * </pre>
	 * 
	 * @param p The requested permission.
	 * @return {@code true} if the specified permission is implied by this
	 *         object; {@code false} otherwise.
	 */
	public boolean implies(Permission p) {
		if (!(p instanceof PackagePermission)) {
			return false;
		}
		PackagePermission requested = (PackagePermission) p;
		if (bundle != null) {
			return false;
		}
		// if requested permission has a filter, then it is an invalid argument
		if (requested.filter != null) {
			return false;
		}
		return implies0(requested, ACTION_NONE);
	}

	/**
	 * Internal implies method. Used by the implies and the permission
	 * collection implies methods.
	 * 
	 * @param requested The requested PackagePermission which has already be
	 *        validated as a proper argument. The requested PackagePermission
	 *        must not have a filter expression.
	 * @param effective The effective actions with which to start.
	 * @return {@code true} if the specified permission is implied by this
	 *         object; {@code false} otherwise.
	 */
	boolean implies0(PackagePermission requested, int effective) {
		/* check actions first - much faster */
		effective |= action_mask;
		final int desired = requested.action_mask;
		if ((effective & desired) != desired) {
			return false;
		}
		/* Get filter if any */
		Filter f = filter;
		if (f == null) {
			return super.implies(requested);
		}
		return f.matches(requested.getProperties());
	}

	/**
	 * Returns the canonical string representation of the
	 * {@code PackagePermission} actions.
	 * 
	 * <p>
	 * Always returns present {@code PackagePermission} actions in the following
	 * order: {@code EXPORTONLY},{@code IMPORT}.
	 * 
	 * @return Canonical string representation of the {@code PackagePermission}
	 *         actions.
	 */
	public String getActions() {
		String result = actions;
		if (result == null) {
			StringBuffer sb = new StringBuffer();
			boolean comma = false;

			int mask = action_mask;
			if ((mask & ACTION_EXPORT) == ACTION_EXPORT) {
				sb.append(EXPORTONLY);
				comma = true;
			}

			if ((mask & ACTION_IMPORT) == ACTION_IMPORT) {
				if (comma)
					sb.append(',');
				sb.append(IMPORT);
			}

			actions = result = sb.toString();
		}
		return result;
	}

	/**
	 * Returns a new {@code PermissionCollection} object suitable for storing
	 * {@code PackagePermission} objects.
	 * 
	 * @return A new {@code PermissionCollection} object.
	 */
	public PermissionCollection newPermissionCollection() {
		return new PackagePermissionCollection();
	}

	/**
	 * Determines the equality of two {@code PackagePermission} objects.
	 * 
	 * This method checks that specified package has the same package name and
	 * {@code PackagePermission} actions as this {@code PackagePermission}
	 * object.
	 * 
	 * @param obj The object to test for equality with this
	 *        {@code PackagePermission} object.
	 * @return {@code true} if {@code obj} is a {@code PackagePermission}, and
	 *         has the same package name and actions as this
	 *         {@code PackagePermission} object; {@code false} otherwise.
	 */
	public boolean equals(Object obj) {
		if (obj == this) {
			return true;
		}

		if (!(obj instanceof PackagePermission)) {
			return false;
		}

		PackagePermission pp = (PackagePermission) obj;

		return (action_mask == pp.action_mask) && getName().equals(pp.getName()) && ((bundle == pp.bundle) || ((bundle != null) && bundle.equals(pp.bundle)));
	}

	/**
	 * Returns the hash code value for this object.
	 * 
	 * @return A hash code value for this object.
	 */
	public int hashCode() {
		int h = 31 * 17 + getName().hashCode();
		h = 31 * h + getActions().hashCode();
		if (bundle != null) {
			h = 31 * h + bundle.hashCode();
		}
		return h;
	}

	/**
	 * WriteObject is called to save the state of this permission object to a
	 * stream. The actions are serialized, and the superclass takes care of the
	 * name.
	 */
	private synchronized void writeObject(java.io.ObjectOutputStream s) throws IOException {
		if (bundle != null) {
			throw new NotSerializableException("cannot serialize");
		}
		// Write out the actions. The superclass takes care of the name
		// call getActions to make sure actions field is initialized
		if (actions == null)
			getActions();
		s.defaultWriteObject();
	}

	/**
	 * readObject is called to restore the state of this permission from a
	 * stream.
	 */
	private synchronized void readObject(java.io.ObjectInputStream s) throws IOException, ClassNotFoundException {
		// Read in the action, then initialize the rest
		s.defaultReadObject();
		setTransients(getName(), parseActions(actions));
	}

	/**
	 * Called by {@code <@link PackagePermission#implies(Permission)>}. This
	 * method is only called on a requested permission which cannot have a
	 * filter set.
	 * 
	 * @return a map of properties for this permission.
	 */
	private Map<String, Object> getProperties() {
		Map<String, Object> result = properties;
		if (result != null) {
			return result;
		}
		final Map<String, Object> map = new HashMap<String, Object>(5);
		map.put("package.name", getName());
		if (bundle != null) {
			AccessController.doPrivileged(new PrivilegedAction<Object>() {
				public Object run() {
					map.put("id", new Long(bundle.getBundleId()));
					map.put("location", bundle.getLocation());
					String name = bundle.getSymbolicName();
					if (name != null) {
						map.put("name", name);
					}
					SignerProperty signer = new SignerProperty(bundle);
					if (signer.isBundleSigned()) {
						map.put("signer", signer);
					}
					return null;
				}
			});
		}
		return properties = map;
	}
}

/**
 * Stores a set of {@code PackagePermission} permissions.
 * 
 * @see java.security.Permission
 * @see java.security.Permissions
 * @see java.security.PermissionCollection
 */

final class PackagePermissionCollection extends PermissionCollection {
	static final long									serialVersionUID	= -3350758995234427603L;
	/**
	 * Table of permissions with names.
	 * 
	 * @GuardedBy this
	 */
	private transient Map<String, PackagePermission>	permissions;

	/**
	 * Boolean saying if "*" is in the collection.
	 * 
	 * @serial
	 * @GuardedBy this
	 */
	private boolean										all_allowed;

	/**
	 * Table of permissions with filter expressions.
	 * 
	 * @serial
	 * @GuardedBy this
	 */
	private Map<String, PackagePermission>				filterPermissions;

	/**
	 * Create an empty PackagePermissions object.
	 */
	public PackagePermissionCollection() {
		permissions = new HashMap<String, PackagePermission>();
		all_allowed = false;
	}

	/**
	 * Adds a permission to this permission collection.
	 * 
	 * @param permission The {@code PackagePermission} object to add.
	 * @throws IllegalArgumentException If the specified permission is not a
	 *         {@code PackagePermission} instance or was constructed with a
	 *         Bundle object.
	 * @throws SecurityException If this {@code PackagePermissionCollection}
	 *         object has been marked read-only.
	 */
	public void add(final Permission permission) {
		if (!(permission instanceof PackagePermission)) {
			throw new IllegalArgumentException("invalid permission: " + permission);
		}
		if (isReadOnly()) {
			throw new SecurityException("attempt to add a Permission to a " + "readonly PermissionCollection");
		}

		final PackagePermission pp = (PackagePermission) permission;
		if (pp.bundle != null) {
			throw new IllegalArgumentException("cannot add to collection: " + pp);
		}

		final String name = pp.getName();
		final Filter f = pp.filter;
		synchronized (this) {
			/* select the bucket for the permission */
			Map<String, PackagePermission> pc;
			if (f != null) {
				pc = filterPermissions;
				if (pc == null) {
					filterPermissions = pc = new HashMap<String, PackagePermission>();
				}
			} else {
				pc = permissions;
			}

			final PackagePermission existing = pc.get(name);
			if (existing != null) {
				final int oldMask = existing.action_mask;
				final int newMask = pp.action_mask;
				if (oldMask != newMask) {
					pc.put(name, new PackagePermission(name, oldMask | newMask));

				}
			} else {
				pc.put(name, pp);
			}

			if (!all_allowed) {
				if (name.equals("*")) {
					all_allowed = true;
				}
			}
		}
	}

	/**
	 * Determines if the specified permissions implies the permissions expressed
	 * in {@code permission}.
	 * 
	 * @param permission The Permission object to compare with this
	 *        {@code PackagePermission} object.
	 * @return {@code true} if {@code permission} is a proper subset of a
	 *         permission in the set; {@code false} otherwise.
	 */
	public boolean implies(final Permission permission) {
		if (!(permission instanceof PackagePermission)) {
			return false;
		}
		final PackagePermission requested = (PackagePermission) permission;
		/* if requested permission has a filter, then it is an invalid argument */
		if (requested.filter != null) {
			return false;
		}
		String requestedName = requested.getName();
		final int desired = requested.action_mask;
		int effective = PackagePermission.ACTION_NONE;

		Collection<PackagePermission> perms;
		synchronized (this) {
			Map<String, PackagePermission> pc = permissions;
			PackagePermission pp;
			/* short circuit if the "*" Permission was added */
			if (all_allowed) {
				pp = pc.get("*");
				if (pp != null) {
					effective |= pp.action_mask;
					if ((effective & desired) == desired) {
						return true;
					}
				}
			}
			/*
			 * strategy: Check for full match first. Then work our way up the
			 * name looking for matches on a.b.*
			 */
			pp = pc.get(requestedName);
			if (pp != null) {
				/* we have a direct hit! */
				effective |= pp.action_mask;
				if ((effective & desired) == desired) {
					return true;
				}
			}
			/* work our way up the tree... */
			int last;
			int offset = requestedName.length() - 1;
			while ((last = requestedName.lastIndexOf(".", offset)) != -1) {
				requestedName = requestedName.substring(0, last + 1) + "*";
				pp = pc.get(requestedName);
				if (pp != null) {
					effective |= pp.action_mask;
					if ((effective & desired) == desired) {
						return true;
					}
				}
				offset = last - 1;
			}
			/*
			 * we don't have to check for "*" as it was already checked before
			 * we were called.
			 */
			pc = filterPermissions;
			if (pc == null) {
				return false;
			}
			perms = pc.values();
		}
		/* iterate one by one over filteredPermissions */
		for (PackagePermission perm : perms) {
			if (perm.implies0(requested, effective)) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Returns an enumeration of all {@code PackagePermission} objects in the
	 * container.
	 * 
	 * @return Enumeration of all {@code PackagePermission} objects.
	 */
	public synchronized Enumeration<Permission> elements() {
		List<Permission> all = new ArrayList<Permission>(permissions.values());
		Map<String, PackagePermission> pc = filterPermissions;
		if (pc != null) {
			all.addAll(pc.values());
		}
		return Collections.enumeration(all);
	}

	/* serialization logic */
	private static final ObjectStreamField[]	serialPersistentFields	= {new ObjectStreamField("permissions", Hashtable.class), new ObjectStreamField("all_allowed", Boolean.TYPE),
			new ObjectStreamField("filterPermissions", HashMap.class)	};

	private synchronized void writeObject(ObjectOutputStream out) throws IOException {
		Hashtable<String, PackagePermission> hashtable = new Hashtable<String, PackagePermission>(permissions);
		ObjectOutputStream.PutField pfields = out.putFields();
		pfields.put("permissions", hashtable);
		pfields.put("all_allowed", all_allowed);
		pfields.put("filterPermissions", filterPermissions);
		out.writeFields();
	}

	private synchronized void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
		ObjectInputStream.GetField gfields = in.readFields();
		Hashtable<String, PackagePermission> hashtable = (Hashtable<String, PackagePermission>) gfields.get("permissions", null);
		permissions = new HashMap<String, PackagePermission>(hashtable);
		all_allowed = gfields.get("all_allowed", false);
		HashMap<String, PackagePermission> fp = (HashMap<String, PackagePermission>) gfields.get("filterPermissions", null);
		filterPermissions = fp;
	}
}