This is a quick and slightly dirty fix to make the code
conform to the latest file format specification. Without
this patch, it's possible to make corrupt files by
specifying start offset that is not a multiple of the
filter's alignment. Custom start offset is almost never
used, so this was only a minor bug.
The xz command line tool doesn't validate the start offset,
so one will get a bit unclear error message if trying to use
an invalid start offset.
use AC_PROG_SED. We don't do anything fancy with sed,
so this should work OK. libtool 2.2 sets SED but 1.5
doesn't, so $(SED) happened to work when using libtool 2.2.
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.
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.
Now configure.ac will get the version number directly from
src/liblzma/api/lzma/version.h. The intent is to reduce the
number of places where the version number is duplicated. In
future, support for displaying Git commit ID may be added too.
- Use call/ret pair to get instruction pointer for PIC.
- Use PIC only if PIC or __PIC__ is #defined.
- The code should work on MinGW and Darwin in addition
to GNU/Linux and Solaris.
Lasse Collin
Jim Meyering