Reword "options required" to "supported options". The previous may have
suggested that the options listed were all required anytime a filter is
used for encoding or decoding. The reword makes this more clear that
adjusting the options is optional.
The lzma_mt_block_size() was previously just an internal function for
the multithreaded .xz encoder. It is used to provide a recommended Block
size for a given filter chain.
This function is helpful to determine the maximum Block size for the
multithreaded .xz encoder when one wants to change the filters between
blocks. Then, this determined Block size can be provided to
lzma_stream_encoder_mt() in the lzma_mt options parameter when
intializing the coder. This requires one to know all the filter chains
they are using before starting to encode (or at least the filter chain
that will need the largest Block size), but that isn't a bad limitation.
Legacy Windows did not need to #include <intrin.h> to use the MSVC
intrinsics. Newer versions likely just issue a warning, but the MSVC
documentation says to include the header file for the intrinsics we use.
GCC and Clang can "pretend" to be MSVC on Windows, so extra checks are
needed in tuklib_integer.h to only include <intrin.h> when it will is
actually needed.
Clang has support for __builtin_clz(), but previously Clang would
fallback to either the MSVC intrinsic or the regular C code. This was
discovered due to a bug where a new version of Clang required the
<intrin.h> header file in order to use the MSVC intrinsics.
Thanks to Anton Kochkov for notifying us about the bug.
If the cache file is not removed, CMake will not reset configurations
back to their default values. In order to make the tests independent, it
is simplest to purge the cache. Unfortunatly, this will slow down the
tests a little and repeat some checks.
The thread method is now configurable for the CMake build. It matches
the Autotools build by allowing ON (pick the best threading method),
OFF (no threading), posix, win95, and vista. If both Windows and
posix threading are both available, then ON will choose Windows
threading. Windows threading will also not use:
target_link_libraries(liblzma Threads::Threads)
since on systems like MinGW-w64 it would link the posix threads
without purpose.
Now, CMake will run similar feature disable tests that the Autotools
version did before. In order to do this without repeating lines in
ci.yml, it now makes sense to use the GitHub Workflow matrix to create
a loop.
This script is only meant to be run as part of the CI build/test process
on machines that are known to have bash (Ubuntu and MacOS). If this
assumption changes in the future, then the bash specific commands will
need to be replaced with a more portable option. For now, it is
convenient to use bash commands.
This allows users to change the features they build either in
CMakeCache.txt or by using a CMake GUI. The sources built for
liblzma are affected by this too, so only the necessary files
will be compiled.
This makes no functional difference in the generated configure
(at least with the Autotools versions I have installed) but this
change might prevent future bugs like the one that was just
fixed in the commit 5a5bd7f871.
This is broken in the releases 5.2.6 to 5.4.2. A workaround
for these releases is to pass EGREP='grep -E' as an argument
to configure in addition to --disable-threads.
The problem appeared when m4/ax_pthread.m4 was updated in
the commit 6629ed929c which
introduced the use of AC_EGREP_CPP. AC_EGREP_CPP calls
AC_REQUIRE([AC_PROG_EGREP]) to set the shell variable EGREP
but this was only executed if POSIX threads were enabled.
Libtool code also has AC_REQUIRE([AC_PROG_EGREP]) but Autoconf
omits it as AC_PROG_EGREP has already been required earlier.
Thus, if not using POSIX threads, the shell variable EGREP
would be undefined in the Libtool code in configure.
ax_pthread.m4 is fine. The bug was in configure.ac which called
AX_PTHREAD conditionally in an incorrect way. Using AS_CASE
ensures that all AC_REQUIREs get always run.
Thanks to Frank Busse for reporting the bug.
Fixes: https://github.com/tukaani-project/xz/issues/45
