Don't use libtool convenience libraries to avoid recently
discovered long-standing subtle but somewhat severe bugs
in libtool (at least 1.5.22 and 2.2.6 are affected). It
was found when porting XZ Utils to Windows
<http://lists.gnu.org/archive/html/libtool/2009-06/msg00070.html>
but the problem is significant also e.g. on GNU/Linux.
Unless --disable-shared is passed to configure, static
library built from a set of convenience libraries will
contain PIC objects. That is, while libtool builds non-PIC
objects too, only PIC objects will be used from the
convenience libraries. On 32-bit x86 (tested on mobile XP2400+),
using PIC instead of non-PIC makes the decompressor 10 % slower
with the default CFLAGS.
So while xz was linked against static liblzma by default,
it got the slower PIC objects unless --disable-shared was
used. I tend develop and benchmark with --disable-shared
due to faster build time, so I hadn't noticed the problem
in benchmarks earlier.
This commit also adds support for building Windows resources
into liblzma and executables.
--format=lzma. This means that xz emulating lzma
doesn't decompress .xz files, while before this
commit it did. The new way is slightly simpler in
code and especially in upcoming documentation.
compressing and decompressing. This should be OK now that
xz automatically scales down the compression settings if
they would exceed the memory usage limit (earlier, the limit
for compression was increased to 90 % because low limit broke
scripts that used "xz -9" on systems with low RAM).
Support spcifying the memory usage limit as a percentage
of RAM (e.g. --memory=50%).
Support --threads=0 to reset the thread limit to the default
value (number of available CPU cores). Use UINT32_MAX instead
of SIZE_MAX as the maximum in args.c. hardware.c was already
expecting uint32_t value.
Cleaned up the output of --help and --long-help.
Don't round the memory usage limit in xzdec --help to avoid
an integer overflow and to not give wrong impression that
the limit is high enough when it may not actually be.
This adds lzdiff, lzgrep, and lzmore to the list of symlinks to install.
It also installs symlinks for the manual pages and removes the new
symlinks on uninstall.
liblzma tries to avoid useless free()/malloc() pairs in
initialization when multiple files are handled using the
same lzma_stream. This didn't work with filter chains
due to comparison of wrong pointers in lzma_next_coder_init(),
making liblzma think that no memory reallocation is needed
even when it actually is.
Easy way to trigger this bug is to decompress two files with
a single xz command. The first file should have e.g. x86+LZMA2
as the filter chain, and the second file just LZMA2.
