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 /*
047 * The offset where the current entry started. -1 if no entry has been
048 * called
049 */
050 private long entryOffset = -1;
051
052 /**
053 * Constructs an Ar input stream with the referenced stream
054 *
055 * @param pInput
056 * the ar input stream
057 */
058 public ArArchiveInputStream(final InputStream pInput) {
059 input = pInput;
060 closed = false;
061 }
062
063 /**
064 * Returns the next AR entry in this stream.
065 *
066 * @return the next AR entry.
067 * @throws IOException
068 * if the entry could not be read
069 */
070 public ArArchiveEntry getNextArEntry() throws IOException {
071 if (currentEntry != null) {
072 final long entryEnd = entryOffset + currentEntry.getLength();
073 while (offset < entryEnd) {
074 int x = read();
075 if (x == -1) {
076 // hit EOF before previous entry was complete
077 // TODO: throw an exception instead?
078 return null;
079 }
080 }
081 currentEntry = null;
082 }
083
084 if (offset == 0) {
085 final byte[] expected = ArchiveUtils.toAsciiBytes(ArArchiveEntry.HEADER);
086 final byte[] realized = new byte[expected.length];
087 final int read = read(realized);
088 if (read != expected.length) {
089 throw new IOException("failed to read header. Occured at byte: " + getCount());
090 }
091 for (int i = 0; i < expected.length; i++) {
092 if (expected[i] != realized[i]) {
093 throw new IOException("invalid header " + ArchiveUtils.toAsciiString(realized));
094 }
095 }
096 }
097
098 if (offset % 2 != 0) {
099 if (read() < 0) {
100 // hit eof
101 return null;
102 }
103 }
104
105 if (input.available() == 0) {
106 return null;
107 }
108
109 final byte[] name = new byte[16];
110 final byte[] lastmodified = new byte[12];
111 final byte[] userid = new byte[6];
112 final byte[] groupid = new byte[6];
113 final byte[] filemode = new byte[8];
114 final byte[] length = new byte[10];
115
116 read(name);
117 read(lastmodified);
118 read(userid);
119 read(groupid);
120 read(filemode);
121 read(length);
122
123 {
124 final byte[] expected = ArchiveUtils.toAsciiBytes(ArArchiveEntry.TRAILER);
125 final byte[] realized = new byte[expected.length];
126 final int read = read(realized);
127 if (read != expected.length) {
128 throw new IOException("failed to read entry header. Occured at byte: " + getCount());
129 }
130 for (int i = 0; i < expected.length; i++) {
131 if (expected[i] != realized[i]) {
132 throw new IOException("invalid entry header. not read the content? Occured at byte: " + getCount());
133 }
134 }
135 }
136
137 entryOffset = offset;
138
139 // SVR4/GNU adds a trailing "/" to names
140 // entry name is stored as ASCII string
141 String temp = ArchiveUtils.toAsciiString(name).trim();
142 if (temp.endsWith("/")) {
143 temp = temp.substring(0, temp.length() - 1);
144 }
145 currentEntry = new ArArchiveEntry(temp, Long.parseLong(new String(length).trim()));
146 return currentEntry;
147 }
148
149 /*
150 * (non-Javadoc)
151 *
152 * @see
153 * org.apache.commons.compress.archivers.ArchiveInputStream#getNextEntry()
154 */
155 public ArchiveEntry getNextEntry() throws IOException {
156 return getNextArEntry();
157 }
158
159 /*
160 * (non-Javadoc)
161 *
162 * @see java.io.InputStream#close()
163 */
164 public void close() throws IOException {
165 if (!closed) {
166 closed = true;
167 input.close();
168 }
169 currentEntry = null;
170 }
171
172 /*
173 * (non-Javadoc)
174 *
175 * @see java.io.InputStream#read(byte[], int, int)
176 */
177 public int read(byte[] b, final int off, final int len) throws IOException {
178 int toRead = len;
179 if (currentEntry != null) {
180 final long entryEnd = entryOffset + currentEntry.getLength();
181 if (len > 0 && entryEnd > offset) {
182 toRead = (int) Math.min(len, entryEnd - offset);
183 } else {
184 return -1;
185 }
186 }
187 final int ret = this.input.read(b, off, toRead);
188 count(ret);
189 offset += (ret > 0 ? ret : 0);
190 return ret;
191 }
192
193 /**
194 * Checks if the signature matches ASCII "!<arch>" followed by a single LF
195 * control character
196 *
197 * @param signature
198 * the bytes to check
199 * @param length
200 * the number of bytes to check
201 * @return true, if this stream is an Ar archive stream, false otherwise
202 */
203 public static boolean matches(byte[] signature, int length) {
204 // 3c21 7261 6863 0a3e
205
206 if (length < 8) {
207 return false;
208 }
209 if (signature[0] != 0x21) {
210 return false;
211 }
212 if (signature[1] != 0x3c) {
213 return false;
214 }
215 if (signature[2] != 0x61) {
216 return false;
217 }
218 if (signature[3] != 0x72) {
219 return false;
220 }
221 if (signature[4] != 0x63) {
222 return false;
223 }
224 if (signature[5] != 0x68) {
225 return false;
226 }
227 if (signature[6] != 0x3e) {
228 return false;
229 }
230 if (signature[7] != 0x0a) {
231 return false;
232 }
233
234 return true;
235 }
236
237 }