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| <document> |
| <properties> |
| <title>Known Limitations and Problems</title> |
| </properties> |
| |
| <body> |
| <p>This page lists the known limitations and problems of Apache |
| Commons Compress™ grouped by the archiving/compression |
| format they apply to.</p> |
| |
| <section name="7Z"> |
| <ul> |
| <li>the format requires the otherwise optional <a |
| href="http://tukaani.org/xz/java.html">XZ for Java</a> |
| library.</li> |
| <li>only <code>File</code>s are supported as input/output, |
| not streams. In Compress 1.7 |
| <code>ArchiveStreamFactory</code> will not auto-detect 7z |
| archives, starting with 1.8 it will throw a |
| <code>StreamingNotSupportedException</code> when reading from |
| a 7z archive.</li> |
| <li>Encryption, solid compression, header compression and |
| LZMA (not LZMA2) are only supported when reading |
| archives</li> |
| <li>Several of the "methods" supported by 7z are not |
| implemented in Compress.</li> |
| <li>No support for multi-volume archives</li> |
| <li>Support for some BCJ filters and the DELTA filter has |
| been added with Compress 1.8. Because of a known bug in |
| version 1.4 of the <a |
| href="http://tukaani.org/xz/java.html">XZ for Java</a> |
| library, archives using BCJ filters will cause an |
| <code>AssertionError</code> when read. If you need support |
| for BCJ filters you must use XZ for Java 1.5 or later.</li> |
| </ul> |
| </section> |
| <section name="AR"> |
| <ul> |
| <li>AR archives can not contain directories - this is a |
| limitation of the format rather than one of Compress' |
| implementation.</li> |
| <li>file names longer than 16 characters are only fully |
| supported using the BSD dialect, the GNU/SRV4 dialect is only |
| supported when reading archives.</li> |
| </ul> |
| </section> |
| <section name="ARJ"> |
| <ul> |
| <li>read-only support</li> |
| <li>no support for compression, encryption or multi-volume |
| archives</li> |
| </ul> |
| </section> |
| <section name="BZIP2"> |
| <p>Versions of Compress prior to 1.4.1 are vulnerable to a |
| possible denial of service attack, see the <a |
| href="security.html">Security Reports</a> page for details.</p> |
| </section> |
| <section name="CPIO"> |
| <p>We are not aware of any problems.</p> |
| </section> |
| <section name="DEFLATE"> |
| <ul> |
| <li><code>CompressorStreamFactory</code> is not able to auto-detect |
| streams using DEFLATE compression.</li> |
| </ul> |
| </section> |
| <section name="DUMP"> |
| <ul> |
| <li>read-only support</li> |
| <li>only the new-fs format is supported</li> |
| <li>the only compression algorithm supported is zlib</li> |
| </ul> |
| </section> |
| <section name="GZIP"> |
| <p>We are not aware of any problems.</p> |
| </section> |
| <section name="JAR"> |
| <p>JAR archives are special ZIP archives, all limitations of <a |
| href="#ZIP">ZIP</a> apply to JAR as well.</p> |
| <ul> |
| <li><code>ArchiveStreamFactory</code> cannot tell JAR |
| archives from ZIP archives and will not auto-detect |
| JARs.</li> |
| <li>Compress doesn't provide special access to the archive's |
| MANIFEST</li> |
| </ul> |
| </section> |
| <section name="LZMA"> |
| <ul> |
| <li>the format requires the otherwise optional <a |
| href="http://tukaani.org/xz/java.html">XZ for Java</a> |
| library.</li> |
| <li>read-only support</li> |
| </ul> |
| </section> |
| <section name="PACK200"> |
| <p>We are not aware of any problems.</p> |
| </section> |
| <section name="SNAPPY"> |
| <ul> |
| <li>read-only support</li> |
| </ul> |
| </section> |
| <section name="TAR"> |
| <ul> |
| <li>sparse files can neither be read nor written</li> |
| <li>only a subset of the GNU and POSIX extensions are |
| supported</li> |
| <li>In Compress 1.6 <code>TarArchiveInputStream</code> could |
| fail to read the full contents of an entry unless the stream |
| was wrapped in a bufferng stream.</li> |
| </ul> |
| </section> |
| <section name="XZ"> |
| <ul> |
| <li>the format requires the otherwise optional <a |
| href="http://tukaani.org/xz/java.html">XZ for Java</a> |
| library.</li> |
| </ul> |
| </section> |
| <section name="Z"> |
| <ul> |
| <li>Prior to Compress 1.8.1 |
| <code>CompressorStreamFactory</code> was not able to |
| auto-detect streams using .Z compression.</li> |
| <li>read-only support</li> |
| </ul> |
| </section> |
| <section name="ZIP"> |
| <ul> |
| <li><code>ZipArchiveInputStream</code> is limited and may |
| even return false contents in some cases, use |
| <code>ZipFile</code> whenever possible. See <a |
| href="zip.html#ZipArchiveInputStream_vs_ZipFile">the ZIP |
| documentation page</a> for details. This limitation is a |
| result of streaming data vs using random access and not a |
| limitation of Compress' specific implementation.</li> |
| <li>only a subset of compression methods are supported, |
| including the most common STORED and DEFLATEd. IMPLODE, |
| SHRINK and BZIP2 support is read-only.</li> |
| <li>no support for encryption or multi-volume archives</li> |
| <li>In versions prior to Compress 1.6 |
| <code>ZipArchiveEntries</code> read from an archive will |
| contain non-zero millisecond values when using Java8 rather |
| than the expected two-second granularity.</li> |
| <li>Compress 1.7 has a known bug where the very first entry |
| of an archive will not be read correctly by |
| <code>ZipArchiveInputStream</code> if it used the STORED |
| method.</li> |
| <li><code>ZipArchiveEntry#getLastModifiedDate</code> uses |
| <code>ZipEntry#getTime</code> under the covers which may |
| return different times for the same archive when using |
| different versions onf Java.</li> |
| </ul> |
| </section> |
| </body> |
| </document> |
