| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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.apache.commons.vfs.provider.tar; |
| |
| /** |
| * This class provides static utility methods to work with byte streams. |
| * |
| * @author <a href="mailto:time@ice.com">Timothy Gerard Endres</a> |
| * @author <a href="mailto:stefano@apache.org">Stefano Mazzocchi</a> |
| * @version $Revision$ $Date$ |
| */ |
| final class TarUtils |
| { |
| /** |
| * Private constructor since this is a utility class with only static methods. |
| */ |
| private TarUtils() |
| { |
| } |
| |
| /** |
| * Parse the checksum octal integer from a header buffer. |
| * |
| * @param offset The offset into the buffer from which to parse. |
| * @param length The number of header bytes to parse. |
| * @param value Description of Parameter |
| * @param buf Description of Parameter |
| * @return The integer value of the entry's checksum. |
| */ |
| public static int getCheckSumOctalBytes(final long value, |
| final byte[] buf, |
| final int offset, |
| final int length) |
| { |
| getOctalBytes(value, buf, offset, length); |
| |
| buf[offset + length - 1] = (byte) ' '; |
| buf[offset + length - 2] = 0; |
| |
| return offset + length; |
| } |
| |
| /** |
| * Parse an octal long integer from a header buffer. |
| * |
| * @param offset The offset into the buffer from which to parse. |
| * @param length The number of header bytes to parse. |
| * @param value Description of Parameter |
| * @param buf Description of Parameter |
| * @return The long value of the octal bytes. |
| */ |
| public static int getLongOctalBytes(final long value, |
| final byte[] buf, |
| final int offset, |
| final int length) |
| { |
| byte[] temp = new byte[length + 1]; |
| |
| getOctalBytes(value, temp, 0, length + 1); |
| System.arraycopy(temp, 0, buf, offset, length); |
| |
| return offset + length; |
| } |
| |
| /** |
| * Determine the number of bytes in an entry name. |
| * |
| * @param offset The offset into the buffer from which to parse. |
| * @param length The number of header bytes to parse. |
| * @param name Description of Parameter |
| * @param buffer Description of Parameter |
| * @return The number of bytes in a header's entry name. |
| */ |
| public static int getNameBytes(final StringBuffer name, |
| final byte[] buffer, |
| final int offset, |
| final int length) |
| { |
| int i; |
| |
| for (i = 0; i < length && i < name.length(); ++i) |
| { |
| buffer[offset + i] = (byte) name.charAt(i); |
| } |
| |
| for (; i < length; ++i) |
| { |
| buffer[offset + i] = 0; |
| } |
| |
| return offset + length; |
| } |
| |
| /** |
| * Parse an octal integer from a header buffer. |
| * |
| * @param offset The offset into the buffer from which to parse. |
| * @param length The number of header bytes to parse. |
| * @return The integer value of the octal bytes. |
| */ |
| public static int getOctalBytes(final long value, |
| final byte[] buffer, |
| final int offset, |
| final int length) |
| { |
| int idx = length - 1; |
| |
| buffer[offset + idx] = 0; |
| --idx; |
| buffer[offset + idx] = (byte) ' '; |
| --idx; |
| |
| if (value == 0) |
| { |
| buffer[offset + idx] = (byte) '0'; |
| --idx; |
| } |
| else |
| { |
| long val = value; |
| while (idx >= 0 && val > 0) |
| { |
| buffer[offset + idx] = (byte) ((byte) '0' + (byte) (val & 7)); |
| val = val >> 3; |
| idx--; |
| } |
| } |
| |
| while (idx >= 0) |
| { |
| buffer[offset + idx] = (byte) ' '; |
| idx--; |
| } |
| |
| return offset + length; |
| } |
| |
| /** |
| * Compute the checksum of a tar entry header. |
| * |
| * @param buffer The tar entry's header buffer. |
| * @return The computed checksum. |
| */ |
| public static long computeCheckSum(final byte[] buffer) |
| { |
| long sum = 0; |
| |
| for (int i = 0; i < buffer.length; ++i) |
| { |
| sum += 255 & buffer[i]; |
| } |
| |
| return sum; |
| } |
| |
| /** |
| * Parse an entry name from a header buffer. |
| * |
| * @param header The header buffer from which to parse. |
| * @param offset The offset into the buffer from which to parse. |
| * @param length The number of header bytes to parse. |
| * @return The header's entry name. |
| */ |
| public static StringBuffer parseName(final byte[] header, |
| final int offset, |
| final int length) |
| { |
| StringBuffer result = new StringBuffer(length); |
| int end = offset + length; |
| |
| for (int i = offset; i < end; ++i) |
| { |
| if (header[i] == 0) |
| { |
| break; |
| } |
| |
| result.append((char) header[i]); |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Parse an octal string from a header buffer. This is used for the file |
| * permission mode value. |
| * |
| * @param header The header buffer from which to parse. |
| * @param offset The offset into the buffer from which to parse. |
| * @param length The number of header bytes to parse. |
| * @return The long value of the octal string. |
| */ |
| public static long parseOctal(final byte[] header, |
| final int offset, |
| final int length) |
| { |
| long result = 0; |
| boolean stillPadding = true; |
| int end = offset + length; |
| |
| for (int i = offset; i < end; ++i) |
| { |
| if (header[i] == 0) |
| { |
| break; |
| } |
| |
| if (header[i] == (byte) ' ' || header[i] == '0') |
| { |
| if (stillPadding) |
| { |
| continue; |
| } |
| |
| if (header[i] == (byte) ' ') |
| { |
| break; |
| } |
| } |
| |
| stillPadding = false; |
| result = (result << 3) + (header[i] - '0'); |
| } |
| |
| return result; |
| } |
| } |