001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019 package org.apache.commons.compress.archivers.ar; 020 021 import java.io.IOException; 022 import java.io.InputStream; 023 024 import org.apache.commons.compress.archivers.ArchiveEntry; 025 import org.apache.commons.compress.archivers.ArchiveInputStream; 026 import org.apache.commons.compress.utils.ArchiveUtils; 027 028 /** 029 * Implements the "ar" archive format as an input stream. 030 * 031 * @NotThreadSafe 032 * 033 */ 034 public class ArArchiveInputStream extends ArchiveInputStream { 035 036 private final InputStream input; 037 private long offset = 0; 038 private boolean closed; 039 040 /* 041 * If getNextEnxtry has been called, the entry metadata is stored in 042 * currentEntry. 043 */ 044 private ArArchiveEntry currentEntry = null; 045 046 // Storage area for extra long names (GNU ar) 047 private byte[] namebuffer = null; 048 049 /* 050 * The offset where the current entry started. -1 if no entry has been 051 * called 052 */ 053 private long entryOffset = -1; 054 055 /** 056 * Constructs an Ar input stream with the referenced stream 057 * 058 * @param pInput 059 * the ar input stream 060 */ 061 public ArArchiveInputStream(final InputStream pInput) { 062 input = pInput; 063 closed = false; 064 } 065 066 /** 067 * Returns the next AR entry in this stream. 068 * 069 * @return the next AR entry. 070 * @throws IOException 071 * if the entry could not be read 072 */ 073 public ArArchiveEntry getNextArEntry() throws IOException { 074 if (currentEntry != null) { 075 final long entryEnd = entryOffset + currentEntry.getLength(); 076 while (offset < entryEnd) { 077 int x = read(); 078 if (x == -1) { 079 // hit EOF before previous entry was complete 080 // TODO: throw an exception instead? 081 return null; 082 } 083 } 084 currentEntry = null; 085 } 086 087 if (offset == 0) { 088 final byte[] expected = ArchiveUtils.toAsciiBytes(ArArchiveEntry.HEADER); 089 final byte[] realized = new byte[expected.length]; 090 final int read = read(realized); 091 if (read != expected.length) { 092 throw new IOException("failed to read header. Occured at byte: " + getBytesRead()); 093 } 094 for (int i = 0; i < expected.length; i++) { 095 if (expected[i] != realized[i]) { 096 throw new IOException("invalid header " + ArchiveUtils.toAsciiString(realized)); 097 } 098 } 099 } 100 101 if (offset % 2 != 0) { 102 if (read() < 0) { 103 // hit eof 104 return null; 105 } 106 } 107 108 if (input.available() == 0) { 109 return null; 110 } 111 112 final byte[] name = new byte[16]; 113 final byte[] lastmodified = new byte[12]; 114 final byte[] userid = new byte[6]; 115 final byte[] groupid = new byte[6]; 116 final byte[] filemode = new byte[8]; 117 final byte[] length = new byte[10]; 118 119 read(name); 120 read(lastmodified); 121 read(userid); 122 read(groupid); 123 read(filemode); 124 read(length); 125 126 { 127 final byte[] expected = ArchiveUtils.toAsciiBytes(ArArchiveEntry.TRAILER); 128 final byte[] realized = new byte[expected.length]; 129 final int read = read(realized); 130 if (read != expected.length) { 131 throw new IOException("failed to read entry trailer. Occured at byte: " + getBytesRead()); 132 } 133 for (int i = 0; i < expected.length; i++) { 134 if (expected[i] != realized[i]) { 135 throw new IOException("invalid entry trailer. not read the content? Occured at byte: " + getBytesRead()); 136 } 137 } 138 } 139 140 entryOffset = offset; 141 142 // GNU ar stores multiple extended filenames in the data section of a file with the name "//", this record is referred to by future headers. A header references an extended filename by storing a "/" followed by a decimal offset to the start of the filename in the extended filename data section. The format of this "//" file itself is simply a list of the long filenames, each separated by one or more LF characters. Note that the decimal offsets are number of characters, not line or string number within the "//" file. 143 // 144 // GNU ar uses a '/' to mark the end of the filename; this allows for the use of spaces without the use of an extended filename. 145 146 // entry name is stored as ASCII string 147 String temp = ArchiveUtils.toAsciiString(name).trim(); 148 149 if (temp.equals("//")){ // GNU extended filenames entry 150 int bufflen = asInt(length); // Assume length will fit in an int 151 namebuffer = new byte[bufflen]; 152 int read = read(namebuffer, 0, bufflen); 153 if (read != bufflen){ 154 throw new IOException("Failed to read complete // record: expected="+bufflen+" read="+read); 155 } 156 currentEntry = new ArArchiveEntry(temp, bufflen); 157 return getNextArEntry(); 158 } else if (temp.endsWith("/")) { // GNU terminator 159 temp = temp.substring(0, temp.length() - 1); 160 } else if (temp.matches("^/\\d+")) {// GNU long filename ref. 161 int offset = Integer.parseInt(temp.substring(1));// get the offset 162 temp = getExtendedName(offset); // convert to the long name 163 } 164 currentEntry = new ArArchiveEntry(temp, asLong(length), asInt(userid), 165 asInt(groupid), asInt(filemode, 8), 166 asLong(lastmodified)); 167 return currentEntry; 168 } 169 170 /** 171 * Get an extended name from the GNU extended name buffer. 172 * 173 * @param offset pointer to entry within the buffer 174 * @return the extended file name; without trailing "/" if present. 175 * @throws IOException if name not found or buffer not set up 176 */ 177 private String getExtendedName(int offset) throws IOException{ 178 if (namebuffer == null) { 179 throw new IOException("Cannot process GNU long filename as no // record was found"); 180 } 181 for(int i=offset; i < namebuffer.length; i++){ 182 if (namebuffer[i]=='\012'){ 183 if (namebuffer[i-1]=='/') { 184 i--; // drop trailing / 185 } 186 return ArchiveUtils.toAsciiString(namebuffer, offset, i-offset); 187 } 188 } 189 throw new IOException("Failed to read entry: "+offset); 190 } 191 private long asLong(byte[] input) { 192 return Long.parseLong(new String(input).trim()); 193 } 194 195 private int asInt(byte[] input) { 196 return asInt(input, 10); 197 } 198 199 private int asInt(byte[] input, int base) { 200 return Integer.parseInt(new String(input).trim(), base); 201 } 202 203 /* 204 * (non-Javadoc) 205 * 206 * @see 207 * org.apache.commons.compress.archivers.ArchiveInputStream#getNextEntry() 208 */ 209 public ArchiveEntry getNextEntry() throws IOException { 210 return getNextArEntry(); 211 } 212 213 /* 214 * (non-Javadoc) 215 * 216 * @see java.io.InputStream#close() 217 */ 218 public void close() throws IOException { 219 if (!closed) { 220 closed = true; 221 input.close(); 222 } 223 currentEntry = null; 224 } 225 226 /* 227 * (non-Javadoc) 228 * 229 * @see java.io.InputStream#read(byte[], int, int) 230 */ 231 public int read(byte[] b, final int off, final int len) throws IOException { 232 int toRead = len; 233 if (currentEntry != null) { 234 final long entryEnd = entryOffset + currentEntry.getLength(); 235 if (len > 0 && entryEnd > offset) { 236 toRead = (int) Math.min(len, entryEnd - offset); 237 } else { 238 return -1; 239 } 240 } 241 final int ret = this.input.read(b, off, toRead); 242 count(ret); 243 offset += (ret > 0 ? ret : 0); 244 return ret; 245 } 246 247 /** 248 * Checks if the signature matches ASCII "!<arch>" followed by a single LF 249 * control character 250 * 251 * @param signature 252 * the bytes to check 253 * @param length 254 * the number of bytes to check 255 * @return true, if this stream is an Ar archive stream, false otherwise 256 */ 257 public static boolean matches(byte[] signature, int length) { 258 // 3c21 7261 6863 0a3e 259 260 if (length < 8) { 261 return false; 262 } 263 if (signature[0] != 0x21) { 264 return false; 265 } 266 if (signature[1] != 0x3c) { 267 return false; 268 } 269 if (signature[2] != 0x61) { 270 return false; 271 } 272 if (signature[3] != 0x72) { 273 return false; 274 } 275 if (signature[4] != 0x63) { 276 return false; 277 } 278 if (signature[5] != 0x68) { 279 return false; 280 } 281 if (signature[6] != 0x3e) { 282 return false; 283 } 284 if (signature[7] != 0x0a) { 285 return false; 286 } 287 288 return true; 289 } 290 291 }