Using return_if_error on lzma_lzma_lclppb_encode was improper because
return_if_error is expecting an lzma_ret value, but
lzma_lzma_lclppb_encode returns a boolean. This could result in
lzma_microlzma_encoder, which would be misleading for applications.
Using CMake to build liblzma should work on a few other OSes
but building the command line tools is still subtly broken.
It is known that shared library versioning may differ between
CMake and Libtool builds on some OSes, most notably Darwin.
The code that parses --memlimit options and --block-list modified
the argv[] when parsing the option string from optarg. This was
visible in "ps auxf" and such and could be confusing. I didn't
understand it back in the day when I wrote that code. Now a copy
is allocated when modifiable strings are needed.
The API docs gave an impression that such checks are done
but they actually weren't done. In practice it made little
difference since the calling code has a bug if these are NULL.
Thanks to Jia Tan for the original patch that checked for
block->filters == NULL.
If someone sets up Clang to define __GNUC__ to 10 or greater
then symvers broke. __has_attribute is supported by such GCC
and Clang versions that don't support __symver__ so this should
be much better and simpler way to detect if __symver__ is
actually supported.
Thanks to Tomasz Gajc for the bug report.
It has some complicated downsides and its usefulness is more limited
than I originally thought. So this change is bad for certain very
specific situations but a generic solution that works for other
filters (and is otherwise better too) is planned anyway. And this
way 7-Zip can use the same compatible filter for the .7z format.
This is still marked as experimental with a new temporary Filter ID.
lzma_str_to_filters() uses static error messages which makes
them not very precise. It tells the position in the string
where an error occurred though which helps quite a bit if
applications take advantage of it. Dynamic error messages can
be added later with a new flag if it seems important enough.
Some file formats need support for LZMA1 streams that don't use
the end of payload marker (EOPM) alias end of stream (EOS) marker.
So far liblzma API has supported decompressing such streams via
lzma_alone_decoder() when .lzma header specifies a known
uncompressed size. Encoding support hasn't been available in the API.
Instead of adding a new LZMA1-only API for this purpose, this commit
adds a new filter ID for use with raw encoder and decoder. The main
benefit of this approach is that then also filter chains are possible,
for example, if someone wants to implement support for .7z files that
use the x86 BCJ filter with LZMA1 (not BCJ2 as that isn't supported
in liblzma).
Jia Tan
Lasse Collin