FileNameDecoder.java

/*
 *
 * Original author: alpha_lam
 * Creation date: ?
 *
 * Source: $HeadURL$
 * Last changed: $LastChangedDate$
 *
 *
 * the unrar licence applies to all junrar source and binary distributions
 * you are not allowed to use this source to re-create the RAR compression algorithm
 *
 * Here some html entities which can be used for escaping javadoc tags:
 * "&":  "&" or "&"
 * "<":  "&#060;" or "&lt;"
 * ">":  "&#062;" or "&gt;"
 * "@":  "&#064;"
 */
package com.github.junrar.rarfile;

public class FileNameDecoder {
    public static int getChar(byte[] name, int pos) {
        return name[pos] & 0xff;
    }

    public static String decode(byte[] name, int encPos) {
        int decPos = 0;
        int flags = 0;
        int flagBits = 0;

        int low = 0;
        int high = 0;
        int highByte = getChar(name, encPos++);
        StringBuilder buf = new StringBuilder();
        while (encPos < name.length) {
            if (flagBits == 0) {
                flags = getChar(name, encPos++);
                flagBits = 8;
            }
            switch (flags >>> 6) {
                case 0:
                    buf.append((char) (getChar(name, encPos++)));
                    ++decPos;
                    break;
                case 1:
                    buf.append((char) (getChar(name, encPos++) + (highByte << 8)));
                    ++decPos;
                    break;
                case 2:
                    low = getChar(name, encPos);
                    high = getChar(name, encPos + 1);
                    buf.append((char) ((high << 8) + low));
                    ++decPos;
                    encPos += 2;
                    break;
                case 3:
                    int length = getChar(name, encPos++);
                    if ((length & 0x80) != 0) {
                        int correction = getChar(name, encPos++);
                        for (length = (length & 0x7f) + 2; length > 0 && decPos < name.length; length--, decPos++) {
                            low = (getChar(name, decPos) + correction) & 0xff;
                            buf.append((char) ((highByte << 8) + low));
                        }
                    } else {
                        for (length += 2; length > 0 && decPos < name.length; length--, decPos++) {
                            buf.append((char) (getChar(name, decPos)));
                        }
                    }
                    break;
            }
            flags = (flags << 2) & 0xff;
            flagBits -= 2;
        }
        return buf.toString();
    }
}