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XZ Utils To-Do List
Known bugs
The test suite is too incomplete.
If the memory 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
The code to detect number of CPU cores doesn't count hyperthreading
as multiple cores. In context of xz, it probably should.
Hyperthreading is good at least with p7zip.
XZ Utils compress some files significantly worse than LZMA Utils.
This is due to faster compression presets used by XZ Utils, and
can often be worked around by using "xz --extreme". With some files
--extreme isn't enough though: it's most likely with files that
compress extremely well, so going from compression ratio of 0.003
to 0.004 means big relative increase in the compressed file size.
xz doesn't quote unprintable characters when it displays file names
given on the command line.
tuklib_exit() doesn't block signals => EINTR is possible.
SIGTSTP is not handled. If xz is stopped, the estimated remaining
time and calculated (de)compression speed won't make sense in the
progress indicator (xz --verbose).
Missing features
xz doesn't support copying extended attributes, access control
lists etc. from source to target file.
Multithreaded compression
Multithreaded decompression
Buffer-to-buffer coding could use less RAM (especially when
decompressing LZMA1 or LZMA2).
I/O library is not implemented (similar to gzopen() in zlib).
It will be a separate library that supports uncompressed, .gz,
.bz2, .lzma, and .xz files.
lzma_strerror() to convert lzma_ret to human readable form?
This is tricky, because the same error codes are used with
slightly different meanings, and this cannot be fixed anymore.
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.
Document the LZMA1 and LZMA2 algorithms.