On Sun, May 12, 2013 at 4:27 PM, Damjan Jovanovic <damjan....@gmail.com> wrote: > On Sun, May 12, 2013 at 12:34 PM, Stefan Bodewig <bode...@apache.org> wrote: >> As for LZMA compression, the required code in XZ for Java's lzma >> subpackage doesn't lend itself to streaming support but it may be >> possible to leverage it anyway. > > I am looking into that now.
With some hacks to its constructor and read() method, I've just gotten XZ's LZMA2InputStream to decompress an LZMA file. The remaining problems and requirements for streaming support are: * RangeDecoder reads the entire file into byte[]. But it's beyond trivial to patch normalize(), its only method that uses the file contents, to use inputStream.read() instead of buf[pos++]. * RangeDecoder wants an exact size, but the lzma CLI tool writes a size of -1 = unknown size. It looks tricky to handle end-of-file without this. * RangeDecoder is final and require package-private static fields from its parent class. Copying it into commons-compress, copying those fields into it, and changing our LZMAInputStream to use it then causes LZMADecoder to also need importing and changing, since it uses the old RangeDecoder and can neither be constructed with the new one, nor can the new one override the final old one. But it inherits from LZMACoder which is package-private. So it looks like we need to either fork all the XZ code, fork a lot of the XZ code which introduces fragility against future XZ changes, or add support for LZMA upstream and use the new XZ version. * For 7z we either need a way to specify all the LZMA properties manually instead of by parsing them from the file header, or a ConcatenatedInputStream class, because in 7z files the LZMA header (see lzma.txt) is not stored with the compressed stream and has to be reconstructed from the file's size and the coder's properties. Anyone want to help? Damjan --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
