001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 * 017 */ 018 019/* 020 * This package is based on the work done by Timothy Gerard Endres 021 * (time@ice.com) to whom the Ant project is very grateful for his great code. 022 */ 023 024package org.apache.activemq.console.command.store.tar; 025 026/** 027 * This class provides static utility methods to work with byte streams. 028 * 029 */ 030// CheckStyle:HideUtilityClassConstructorCheck OFF (bc) 031public class TarUtils { 032 033 private static final int BYTE_MASK = 255; 034 035 /** 036 * Parse an octal string from a header buffer. This is used for the 037 * file permission mode value. 038 * 039 * @param header The header buffer from which to parse. 040 * @param offset The offset into the buffer from which to parse. 041 * @param length The number of header bytes to parse. 042 * @return The long value of the octal string. 043 */ 044 public static long parseOctal(byte[] header, int offset, int length) { 045 long result = 0; 046 boolean stillPadding = true; 047 int end = offset + length; 048 049 for (int i = offset; i < end; ++i) { 050 if (header[i] == 0) { 051 break; 052 } 053 054 if (header[i] == (byte) ' ' || header[i] == '0') { 055 if (stillPadding) { 056 continue; 057 } 058 059 if (header[i] == (byte) ' ') { 060 break; 061 } 062 } 063 064 stillPadding = false; 065 // CheckStyle:MagicNumber OFF 066 result = (result << 3) + (header[i] - '0'); 067 // CheckStyle:MagicNumber ON 068 } 069 070 return result; 071 } 072 073 /** 074 * Parse an entry name from a header buffer. 075 * 076 * @param header The header buffer from which to parse. 077 * @param offset The offset into the buffer from which to parse. 078 * @param length The number of header bytes to parse. 079 * @return The header's entry name. 080 */ 081 public static StringBuffer parseName(byte[] header, int offset, int length) { 082 StringBuffer result = new StringBuffer(length); 083 int end = offset + length; 084 085 for (int i = offset; i < end; ++i) { 086 if (header[i] == 0) { 087 break; 088 } 089 090 result.append((char) header[i]); 091 } 092 093 return result; 094 } 095 096 /** 097 * Determine the number of bytes in an entry name. 098 * 099 * @param name The header name from which to parse. 100 * @param buf The buffer from which to parse. 101 * @param offset The offset into the buffer from which to parse. 102 * @param length The number of header bytes to parse. 103 * @return The number of bytes in a header's entry name. 104 */ 105 public static int getNameBytes(StringBuffer name, byte[] buf, int offset, int length) { 106 int i; 107 108 for (i = 0; i < length && i < name.length(); ++i) { 109 buf[offset + i] = (byte) name.charAt(i); 110 } 111 112 for (; i < length; ++i) { 113 buf[offset + i] = 0; 114 } 115 116 return offset + length; 117 } 118 119 /** 120 * Parse an octal integer from a header buffer. 121 * 122 * @param value The header value 123 * @param buf The buffer from which to parse. 124 * @param offset The offset into the buffer from which to parse. 125 * @param length The number of header bytes to parse. 126 * @return The integer value of the octal bytes. 127 */ 128 public static int getOctalBytes(long value, byte[] buf, int offset, int length) { 129 int idx = length - 1; 130 131 buf[offset + idx] = 0; 132 --idx; 133 buf[offset + idx] = (byte) ' '; 134 --idx; 135 136 if (value == 0) { 137 buf[offset + idx] = (byte) '0'; 138 --idx; 139 } else { 140 for (long val = value; idx >= 0 && val > 0; --idx) { 141 // CheckStyle:MagicNumber OFF 142 buf[offset + idx] = (byte) ((byte) '0' + (byte) (val & 7)); 143 val = val >> 3; 144 // CheckStyle:MagicNumber ON 145 } 146 } 147 148 for (; idx >= 0; --idx) { 149 buf[offset + idx] = (byte) ' '; 150 } 151 152 return offset + length; 153 } 154 155 /** 156 * Parse an octal long integer from a header buffer. 157 * 158 * @param value The header value 159 * @param buf The buffer from which to parse. 160 * @param offset The offset into the buffer from which to parse. 161 * @param length The number of header bytes to parse. 162 * @return The long value of the octal bytes. 163 */ 164 public static int getLongOctalBytes(long value, byte[] buf, int offset, int length) { 165 byte[] temp = new byte[length + 1]; 166 167 getOctalBytes(value, temp, 0, length + 1); 168 System.arraycopy(temp, 0, buf, offset, length); 169 170 return offset + length; 171 } 172 173 /** 174 * Parse the checksum octal integer from a header buffer. 175 * 176 * @param value The header value 177 * @param buf The buffer from which to parse. 178 * @param offset The offset into the buffer from which to parse. 179 * @param length The number of header bytes to parse. 180 * @return The integer value of the entry's checksum. 181 */ 182 public static int getCheckSumOctalBytes(long value, byte[] buf, int offset, int length) { 183 getOctalBytes(value, buf, offset, length); 184 185 buf[offset + length - 1] = (byte) ' '; 186 buf[offset + length - 2] = 0; 187 188 return offset + length; 189 } 190 191 /** 192 * Compute the checksum of a tar entry header. 193 * 194 * @param buf The tar entry's header buffer. 195 * @return The computed checksum. 196 */ 197 public static long computeCheckSum(byte[] buf) { 198 long sum = 0; 199 200 for (int i = 0; i < buf.length; ++i) { 201 sum += BYTE_MASK & buf[i]; 202 } 203 204 return sum; 205 } 206}