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| -rw-r--r-- | TODO | 117 |
1 files changed, 27 insertions, 90 deletions
@@ -1,109 +1,46 @@ -LZMA Utils TODO List --------------------- +XZ Utils To-Do List +=================== -Major missing features +Known bugs +---------- - Memory limits in the command line tool apply only to compression. + The test suite is too incomplete. - Threading support in the lzma command line tool is still primitive. - It cannot split a file in pieces yet. + If the memor usage limit is less than about 13 MiB, xz is unable to + automatically scale down the compression settings enough even though + it would be possible by switching from BT2/BT3/BT4 match finder to + HC3/HC4. - The --list mode isn't implemented in the command line tool. - Handling of Multi-Block Stream information should be separated - from Stream encoder and decoder. Those would be useful to implement - multi-threaded coding in applications. +Missing features +---------------- - Buffer to buffer coding is not implemented in liblzma. Probably - a naive version should be written first, which would simply wrap - things around lzma_stream. Later, there should be separate buffer - coding functions, that are slightly faster (less memcpy()) and - have smaller memory usage than the functions using lzma_stream. + "xz --list" - libzfile is not implemented. + xz could create sparse files when decompressing. (Some prototyping + has been done.) - LZMA filter doesn't support predefined history buffer. + xz doesn't support copying extended attributes, access control + lists etc. from source to target file. + Multithreaded compression -Security + Multithreaded decompression - Search for bugs, especially security related issues. Security is - important in every piece of code in LZMA Utils, but it is extremely - important in the decoder part of liblzma. + Buffer-to-buffer coding could use less RAM (especially when + decompressing LZMA1 or LZMA2). - Subblock: If there is LZMA as a Subfilter but without EOPM, can it - trigger infinite loop when Subblock's "Unset Subfilter" flag is hit? - - Similarly, can LZ decoder get stuck in infinite loop if the next - filter in the chain returns LZMA_STREAM_END but the decoded data - doesn't allow finishing the LZ decoding? - - -Reliability - - Create a test suite to be run with "make check". - - Should we use strlimit() and getrlimit() for memory usage limitting? - - -Performance - - Benchmark the CRC code on non-x86 CPUs. Won't have huge effect on - overall speed, but it would still be nice to know what algorithm - variant is the best on different CPUs. - - -Third party support - - Add support for LZMA to various applications. This naturally requires - cooperating with the authors of the specific applications. - * GNU grep and GNU diffutils: BSD grep already uses zlib directly - instead of ugly shell scripts. It would be nice to get similar - feature into relevant GNU tools. With libzfile, multiple - compression formats would be easy to support. - * kioslave for KDE - * Magic for the `file' command - * GNU Midnight Commander - * GNU Texinfo - * The `man' command - * Package managers - - Test the patches already written. The patches should be sent to - upstream developers _once_ LZMA Utils APIs are stable enough (so - people don't need to fix those patches all the time). - - Mandriva has quite a few patches. Some of them are OK, some need - adapting for new LZMA Utils. + I/O library is not implemented. It will possibly be named libzzf. Documentation +------------- - Revise the man page of lzma command line tool. - - If the Doxygen docs aren't enough, write good Texinfo manual for - liblzma. It's been a long time I've even tried to build the Doxygen - docs, so they may look quite bad at the moment. - - Document LZMA as an algorithm. It would be great to have detailed - description of the algorithm in English. Many people think, that - reading the source code is not the optimal way to learn how LZMA - works. - - -Other - - Some things return LZMA_PROG_ERROR with invalid options, some - LZMA_HEADER_ERROR. These must be checked carefully and made so - that LZMA_HEADER_ERROR is used only when the given option could - make sense in future version of libzma. - - lzma_restrict vs. restrict - - Usage of LZMA_RUN vs. LZMA_FINISH with Metadata coders. + Some tutorial is needed for liblzma. I have planned to write some + extremely well commented example programs, which would work as + a tutorial. I suppose the Doxygen tags are quite OK as a quick + reference once one is familiar with the liblzma API. - Port the Deflate implementation from 7-Zip into liblzma. 7-Zip's - Deflate compresses better than zlib, gzip or Info-ZIP. I don't - know if Deflate will be included in .lzma format (probably not), - but it's still useful once we also add support for .gz file format. + Document the LZMA1 and LZMA2 algorithms. |