/*

 * Copyright 1997-2009 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * 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).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.io;

import java.security.*;

import java.util.Enumeration;

import java.util.List;

import java.util.ArrayList;

import java.util.Vector;

import java.util.Collections;

import java.io.ObjectStreamField;

import java.io.ObjectOutputStream;

import java.io.ObjectInputStream;

import java.io.IOException;

import sun.security.util.SecurityConstants;

/**

 * This class represents access to a file or directory.  A FilePermission consists

 * of a pathname and a set of actions valid for that pathname.

 * <P>

 * Pathname is the pathname of the file or directory granted the specified

 * actions. A pathname that ends in "/*" (where "/" is

 * the file separator character, <code>File.separatorChar</code>) indicates

 * all the files and directories contained in that directory. A pathname

 * that ends with "/-" indicates (recursively) all files

 * and subdirectories contained in that directory. A pathname consisting of

 * the special token "&lt;&lt;ALL FILES&gt;&gt;" matches <b>any</b> file.

 * <P>

 * Note: A pathname consisting of a single "*" indicates all the files

 * in the current directory, while a pathname consisting of a single "-"

 * indicates all the files in the current directory and

 * (recursively) all files and subdirectories contained in the current

 * directory.

 * <P>

 * The actions to be granted are passed to the constructor in a string containing

 * a list of one or more comma-separated keywords. The possible keywords are

 * "read", "write", "execute", "delete", and "readlink". Their meaning is

 * defined as follows:

 * <P>

 * <DL>

 *    <DT> read <DD> read permission

 *    <DT> write <DD> write permission

 *    <DT> execute

 *    <DD> execute permission. Allows <code>Runtime.exec</code> to

 *         be called. Corresponds to <code>SecurityManager.checkExec</code>.

 *    <DT> delete

 *    <DD> delete permission. Allows <code>File.delete</code> to

 *         be called. Corresponds to <code>SecurityManager.checkDelete</code>.

 *    <DT> readlink

 *    <DD> read link permission. Allows the target of a

 *         <a href="../nio/file/package-summary.html#links">symbolic link</a>

 *         to be read by invoking the {@link java.nio.file.Path#readSymbolicLink

 *         readSymbolicLink } method.

 * </DL>

 * <P>

 * The actions string is converted to lowercase before processing.

 * <P>

 * Be careful when granting FilePermissions. Think about the implications

 * of granting read and especially write access to various files and

 * directories. The "<<ALL FILES>>" permission with write action is

 * especially dangerous. This grants permission to write to the entire

 * file system. One thing this effectively allows is replacement of the

 * system binary, including the JVM runtime environment.

 *

 * <p>Please note: Code can always read a file from the same

 * directory it's in (or a subdirectory of that directory); it does not

 * need explicit permission to do so.

 *

 * @see java.security.Permission

 * @see java.security.Permissions

 * @see java.security.PermissionCollection

 *

 *

 * @author Marianne Mueller

 * @author Roland Schemers

 * @since 1.2

 *

 * @serial exclude

 */

public final class FilePermission extends Permission implements Serializable {

    /**

     * Execute action.

     */

    private final static int EXECUTE = 0x1;

    /**

     * Write action.

     */

    private final static int WRITE   = 0x2;

    /**

     * Read action.

     */

    private final static int READ    = 0x4;

    /**

     * Delete action.

     */

    private final static int DELETE  = 0x8;

    /**

     * Read link action.

     */

    private final static int READLINK    = 0x10;

    /**

     * All actions (read,write,execute,delete,readlink)

     */

    private final static int ALL     = READ|WRITE|EXECUTE|DELETE|READLINK;

    /**

     * No actions.

     */

    private final static int NONE    = 0x0;

    // the actions mask

    private transient int mask;

    // does path indicate a directory? (wildcard or recursive)

    private transient boolean directory;

    // is it a recursive directory specification?

    private transient boolean recursive;

    /**

     * the actions string.

     *

     * @serial

     */

    private String actions; // Left null as long as possible, then

                            // created and re-used in the getAction function.

    // canonicalized dir path. In the case of

    // directories, it is the name "/blah/*" or "/blah/-" without

    // the last character (the "*" or "-").

    private transient String cpath;

    // static Strings used by init(int mask)

    private static final char RECURSIVE_CHAR = '-';

    private static final char WILD_CHAR = '*';

/*

    public String toString()

    {

        StringBuffer sb = new StringBuffer();

        sb.append("***\n");

        sb.append("cpath = "+cpath+"\n");

        sb.append("mask = "+mask+"\n");

        sb.append("actions = "+getActions()+"\n");

        sb.append("directory = "+directory+"\n");

        sb.append("recursive = "+recursive+"\n");

        sb.append("***\n");

        return sb.toString();

    }

*/

    private static final long serialVersionUID = 7930732926638008763L;

    /**

     * initialize a FilePermission object. Common to all constructors.

     * Also called during de-serialization.

     *

     * @param mask the actions mask to use.

     *

     */

    private void init(int mask)

    {

        if ((mask & ALL) != mask)

                throw new IllegalArgumentException("invalid actions mask");

        if (mask == NONE)

                throw new IllegalArgumentException("invalid actions mask");

        if ((cpath = getName()) == null)

                throw new NullPointerException("name can't be null");

        this.mask = mask;

        if (cpath.equals("<<ALL FILES>>")) {

            directory = true;

            recursive = true;

            cpath = "";

            return;

        }

        // store only the canonical cpath if possible

        cpath = AccessController.doPrivileged(new PrivilegedAction<String>() {

            public String run() {

                try {

                } catch (IOException ioe) {

                    return cpath;

                }

            }

        });

        int len = cpath.length();

        char last = ((len > 0) ? cpath.charAt(len - 1) : 0);

        if (last == RECURSIVE_CHAR &&

            cpath.charAt(len - 2) == File.separatorChar) {

            directory = true;

            recursive = true;

            cpath = cpath.substring(0, --len);

        } else if (last == WILD_CHAR &&

            cpath.charAt(len - 2) == File.separatorChar) {

            directory = true;

            //recursive = false;

            cpath = cpath.substring(0, --len);

        } else {

            // overkill since they are initialized to false, but

            // commented out here to remind us...

            //directory = false;

            //recursive = false;

        }

        // XXX: at this point the path should be absolute. die if it isn't?

    }

    /**

     * Creates a new FilePermission object with the specified actions.

     * <i>path</i> is the pathname of a file or directory, and <i>actions</i>

     * contains a comma-separated list of the desired actions granted on the

     * file or directory. Possible actions are

     * "read", "write", "execute", "delete", and "readlink".

     *

     * <p>A pathname that ends in "/*" (where "/" is

     * the file separator character, <code>File.separatorChar</code>)

     * indicates all the files and directories contained in that directory.

     * A pathname that ends with "/-" indicates (recursively) all files and

     * subdirectories contained in that directory. The special pathname

     * "<<ALL FILES>>" matches any file.

     *

     * <p>A pathname consisting of a single "*" indicates all the files

     * in the current directory, while a pathname consisting of a single "-"

     * indicates all the files in the current directory and

     * (recursively) all files and subdirectories contained in the current

     * directory.

     *

     * <p>A pathname containing an empty string represents an empty path.

     *

     * @param path the pathname of the file/directory.

     * @param actions the action string.

     *

     * @throws IllegalArgumentException

     *          If actions is <code>null</code>, empty or contains an action

     *          other than the specified possible actions.

     */

    public FilePermission(String path, String actions)

    {

        super(path);

        init(getMask(actions));

    }

    /**

     * Creates a new FilePermission object using an action mask.

     * More efficient than the FilePermission(String, String) constructor.

     * Can be used from within

     * code that needs to create a FilePermission object to pass into the

     * <code>implies</code> method.

     *

     * @param path the pathname of the file/directory.

     * @param mask the action mask to use.

     */

    // package private for use by the FilePermissionCollection add method

    FilePermission(String path, int mask)

    {

        super(path);

        init(mask);

    }

    /**

     * Checks if this FilePermission object "implies" the specified permission.

     * <P>

     * More specifically, this method returns true if:<p>

     * <ul>

     * <li> <i>p</i> is an instanceof FilePermission,<p>

     * <li> <i>p</i>'s actions are a proper subset of this

     * object's actions, and <p>

     * <li> <i>p</i>'s pathname is implied by this object's

     *      pathname. For example, "/tmp/*" implies "/tmp/foo", since

     *      "/tmp/*" encompasses all files in the "/tmp" directory,

     *      including the one named "foo".

     * </ul>

     *

     * @param p the permission to check against.

     *

     * @return <code>true</code> if the specified permission is not

     *                  <code>null</code> and is implied by this object,

     *                  <code>false</code> otherwise.

     */

    public boolean implies(Permission p) {

        if (!(p instanceof FilePermission))

            return false;

        FilePermission that = (FilePermission) p;

        // we get the effective mask. i.e., the "and" of this and that.

        // They must be equal to that.mask for implies to return true.

        return ((this.mask & that.mask) == that.mask) && impliesIgnoreMask(that);

    }

    /**

     * Checks if the Permission's actions are a proper subset of the

     * this object's actions. Returns the effective mask iff the

     * this FilePermission's path also implies that FilePermission's path.

     *

     * @param that the FilePermission to check against.

     * @param exact return immediately if the masks are not equal

     * @return the effective mask

     */

    boolean impliesIgnoreMask(FilePermission that) {

        if (this.directory) {

            if (this.recursive) {

                // make sure that.path is longer then path so

                // something like /foo/- does not imply /foo

                if (that.directory) {

                    return (that.cpath.length() >= this.cpath.length()) &&

                            that.cpath.startsWith(this.cpath);

                }  else {

                    return ((that.cpath.length() > this.cpath.length()) &&

                        that.cpath.startsWith(this.cpath));

                }

            } else {

                if (that.directory) {

                    // if the permission passed in is a directory

                    // specification, make sure that a non-recursive

                    // permission (i.e., this object) can't imply a recursive

                    // permission.

                    if (that.recursive)

                        return false;

                    else

                        return (this.cpath.equals(that.cpath));

                } else {

                    int last = that.cpath.lastIndexOf(File.separatorChar);

                    if (last == -1)

                        return false;

                    else {

                        // this.cpath.equals(that.cpath.substring(0, last+1));

                        // Use regionMatches to avoid creating new string

                        return (this.cpath.length() == (last + 1)) &&

                            this.cpath.regionMatches(0, that.cpath, 0, last+1);

                    }

                }

            }

        } else if (that.directory) {

            // if this is NOT recursive/wildcarded,

            // do not let it imply a recursive/wildcarded permission

            return false;

        } else {

            return (this.cpath.equals(that.cpath));

        }

    }

    /**

     * Checks two FilePermission objects for equality. Checks that <i>obj</i> is

     * a FilePermission, and has the same pathname and actions as this object.

     * <P>

     * @param obj the object we are testing for equality with this object.

     * @return <code>true</code> if obj is a FilePermission, and has the same

     *          pathname and actions as this FilePermission object,

     *          <code>false</code> otherwise.

     */

    public boolean equals(Object obj) {

        if (obj == this)

            return true;

        if (! (obj instanceof FilePermission))

            return false;

        FilePermission that = (FilePermission) obj;

        return (this.mask == that.mask) &&

            this.cpath.equals(that.cpath) &&

            (this.directory == that.directory) &&

            (this.recursive == that.recursive);

    }

    /**

     * Returns the hash code value for this object.

     *

     * @return a hash code value for this object.

     */

    public int hashCode() {

        return this.cpath.hashCode();

    }

    /**

     * Converts an actions String to an actions mask.

     *

     * @param action the action string.

     * @return the actions mask.

     */

    private static int getMask(String actions) {

        int mask = NONE;

        // Null action valid?

        if (actions == null) {

            return mask;

        }

        // Check against use of constants (used heavily within the JDK)

        if (actions == SecurityConstants.FILE_READ_ACTION) {

            return READ;

        } else if (actions == SecurityConstants.FILE_WRITE_ACTION) {

            return WRITE;

        } else if (actions == SecurityConstants.FILE_EXECUTE_ACTION) {

            return EXECUTE;

        } else if (actions == SecurityConstants.FILE_DELETE_ACTION) {

            return DELETE;

        } else if (actions == SecurityConstants.FILE_READLINK_ACTION) {

            return READLINK;

        }

        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 >= 3 && (a[i-3] == 'r' || a[i-3] == 'R') &&

                          (a[i-2] == 'e' || a[i-2] == 'E') &&

                          (a[i-1] == 'a' || a[i-1] == 'A') &&

                          (a[i] == 'd' || a[i] == 'D'))

            {

                matchlen = 4;

                mask |= READ;

            } else if (i >= 4 && (a[i-4] == 'w' || a[i-4] == 'W') &&

                                 (a[i-3] == 'r' || a[i-3] == 'R') &&

                                 (a[i-2] == 'i' || a[i-2] == 'I') &&

                                 (a[i-1] == 't' || a[i-1] == 'T') &&

                                 (a[i] == 'e' || a[i] == 'E'))

            {

                matchlen = 5;

                mask |= WRITE;

            } else if (i >= 6 && (a[i-6] == 'e' || a[i-6] == 'E') &&

                                 (a[i-5] == 'x' || a[i-5] == 'X') &&

                                 (a[i-4] == 'e' || a[i-4] == 'E') &&

                                 (a[i-3] == 'c' || a[i-3] == 'C') &&

                                 (a[i-2] == 'u' || a[i-2] == 'U') &&

                                 (a[i-1] == 't' || a[i-1] == 'T') &&

                                 (a[i] == 'e' || a[i] == 'E'))

            {

                matchlen = 7;

                mask |= EXECUTE;

            } else if (i >= 5 && (a[i-5] == 'd' || a[i-5] == 'D') &&

                                 (a[i-4] == 'e' || a[i-4] == 'E') &&

                                 (a[i-3] == 'l' || a[i-3] == 'L') &&

                                 (a[i-2] == 'e' || a[i-2] == 'E') &&

                                 (a[i-1] == 't' || a[i-1] == 'T') &&

                                 (a[i] == 'e' || a[i] == 'E'))

            {

                matchlen = 6;

                mask |= DELETE;

            } else if (i >= 7 && (a[i-7] == 'r' || a[i-7] == 'R') &&

                                 (a[i-6] == 'e' || a[i-6] == 'E') &&

                                 (a[i-5] == 'a' || a[i-5] == 'A') &&

                                 (a[i-4] == 'd' || a[i-4] == 'D') &&

                                 (a[i-3] == 'l' || a[i-3] == 'L') &&

                                 (a[i-2] == 'i' || a[i-2] == 'I') &&

                                 (a[i-1] == 'n' || a[i-1] == 'N') &&

                                 (a[i] == 'k' || a[i] == 'K'))

            {

                matchlen = 8;

                mask |= READLINK;

            } else {

                // parse error

                throw new IllegalArgumentException(

                        "invalid permission: " + actions);