- /*
- * Copyright 2000,2002,2004 The Apache Software Foundation
- *
- * 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.
- *
- */
-
- /*
- * This package is based on the work done by Timothy Gerard Endres
- * (time@ice.com) to whom the Ant project is very grateful for his great code.
- */
-
- package org.apache.tools.tar;
-
- /**
- * This class provides static utility methods to work with byte streams.
- *
- */
- public class TarUtils {
-
- /**
- * 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(byte[] header, int offset, 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;
- }
-
- /**
- * 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(byte[] header, int offset, 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;
- }
-
- /**
- * Determine the number of bytes in an entry name.
- *
- * @param name The header name 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 number of bytes in a header's entry name.
- */
- public static int getNameBytes(StringBuffer name, byte[] buf, int offset, int length) {
- int i;
-
- for (i = 0; i < length && i < name.length(); ++i) {
- buf[offset + i] = (byte) name.charAt(i);
- }
-
- for (; i < length; ++i) {
- buf[offset + i] = 0;
- }
-
- return offset + length;
- }
-
- /**
- * Parse an octal integer from a header buffer.
- *
- * @param value The header value
- * @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(long value, byte[] buf, int offset, int length) {
- int idx = length - 1;
-
- buf[offset + idx] = 0;
- --idx;
- buf[offset + idx] = (byte) ' ';
- --idx;
-
- if (value == 0) {
- buf[offset + idx] = (byte) '0';
- --idx;
- } else {
- for (long val = value; idx >= 0 && val > 0; --idx) {
- buf[offset + idx] = (byte) ((byte) '0' + (byte) (val & 7));
- val = val >> 3;
- }
- }
-
- for (; idx >= 0; --idx) {
- buf[offset + idx] = (byte) ' ';
- }
-
- return offset + length;
- }
-
- /**
- * Parse an octal long integer from a header buffer.
- *
- * @param value The header value
- * @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 bytes.
- */
- public static int getLongOctalBytes(long value, byte[] buf, int offset, int length) {
- byte[] temp = new byte[length + 1];
-
- getOctalBytes(value, temp, 0, length + 1);
- System.arraycopy(temp, 0, buf, offset, length);
-
- return offset + length;
- }
-
- /**
- * Parse the checksum octal integer from a header buffer.
- *
- * @param value The header value
- * @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 entry's checksum.
- */
- public static int getCheckSumOctalBytes(long value, byte[] buf, int offset, int length) {
- getOctalBytes(value, buf, offset, length);
-
- buf[offset + length - 1] = (byte) ' ';
- buf[offset + length - 2] = 0;
-
- return offset + length;
- }
-
- /**
- * Compute the checksum of a tar entry header.
- *
- * @param buf The tar entry's header buffer.
- * @return The computed checksum.
- */
- public static long computeCheckSum(byte[] buf) {
- long sum = 0;
-
- for (int i = 0; i < buf.length; ++i) {
- sum += 255 & buf[i];
- }
-
- return sum;
- }
- }