The first member of lzma_lz_encoder doesn't necessarily need to be set
to NULL since it will always be set before anything tries to use it.
However the function pointer members must be set to NULL since other
functions rely on this NULL value to determine if this behavior is
supported or not.
This fixes a somewhat serious bug, where the options_update() and
set_out_limit() function pointers are not set to NULL. This seems to
have been forgotten since these function pointers were added many years
after the original two (code() and end()).
The problem is that by not setting this to NULL we are relying on the
memory allocation to zero things out if lzma_filters_update() is called
on a LZMA1 encoder. The function pointer for set_out_limit() is less
serious because there is not an API function that could call this in an
incorrect way. set_out_limit() is only called by the MicroLZMA encoder,
which must use LZMA1 where set_out_limit() is always set. Its currently
not possible to call set_out_limit() on an LZMA2 encoder at this time.
So calling lzma_filters_update() on an LZMA1 encoder had undefined
behavior since its possible that memory could be manipulated so the
options_update member pointed to a different instruction sequence.
This is unlikely to be a bug in an existing application since it relies
on calling lzma_filters_update() on an LZMA1 encoder in the first place.
For instance, it does not affect xz because lzma_filters_update() can
only be used when encoding to the .xz format.
lzma_raw_encoder() and lzma_raw_encoder_init() used "options" as the
parameter name instead of "filters" (used by the declaration). "filters"
is more clear since the parameter represents the list of filters passed
to the raw encoder, each of which contains filter options.
lzma_encoder_init() did not check for NULL options, but
lzma2_encoder_init() did. This is more of a code style improvement than
anything else to help make lzma_encoder_init() and lzma2_encoder_init()
more similar.
Since GCC version 10, GCC no longer complains about simple implicit
integer conversions with Arithmetic operators.
For instance:
uint8_t a = 5;
uint32_t b = a + 5;
Give a warning on GCC 9 and earlier but this:
uint8_t a = 5;
uint32_t b = (a + 5) * 2;
Gives a warning with GCC 10+.
The new is_tty() will report if a file descriptor is a terminal or not.
On POSIX systems, it is a wrapper around isatty(). However, the native
Windows implementation of isatty() will return true for all character
devices, not just terminals. So is_tty() has a special case for Windows
so it can use alternative Windows API functions to determine if a file
descriptor is a terminal.
This fixes a bug with MSVC and MinGW-w64 builds that refused to read from
or write to non-terminal character devices because xz thought it was a
terminal. For instance:
xz foo -c > /dev/null
would fail because /dev/null was assumed to be a terminal.
This tests some complicated interactions with the --suffix= option.
The suffix option must be used with --format=raw, but can optionally
be used to override the default .xz suffix.
This test also verifies some recent bugs have been correctly solved
and to hopefully avoid further regressions in the future.
The suffix refactor done in 99575947a5
had a small regression where raw format compression to standard out
failed if a suffix was not set. In this case, setting the suffix did
not make sense since a file is not created.
Now, xz should only fail when a suffix is not provided when it is
actually needed.
For instance:
echo "foo" | xz --format=raw --lzma2 | wc -c
does not need a suffix check since it creates no files. But:
xz --format=raw --lzma2 --suffix=.bar foo
Needs the suffix to be set since it must create foo.bar.
The macro lzma_attr_visibility_hidden has to be defined to make
fastpos.h usable. The visibility attribute is irrelevant to
fastpos_tablegen.c so simply #define the macro to an empty value.
fastpos_tablegen.c is never built by the included build systems
and so the problem wasn't noticed earlier. It's just a standalone
program for generating fastpos_table.c.
Fixes: https://github.com/tukaani-project/xz/pull/69
Thanks to GitHub user Jamaika1.
In ELF shared libs:
-fvisibility=hidden affects definitions of symbols but not
declarations.[*] This doesn't affect direct calls to functions
inside liblzma as a linker can replace a call to lzma_foo@plt
with a call directly to lzma_foo when -fvisibility=hidden is used.
[*] It has to be like this because otherwise every installed
header file would need to explictly set the symbol visibility
to default.
When accessing extern variables that aren't defined in the
same translation unit, compiler assumes that the variable has
the default visibility and thus indirection is needed. Unlike
function calls, linker cannot optimize this.
Using __attribute__((__visibility__("hidden"))) with the extern
variable declarations tells the compiler that indirection isn't
needed because the definition is in the same shared library.
About 15+ years ago, someone told me that it would be good if
the CRC tables would be defined in the same translation unit
as the C code of the CRC functions. While I understood that it
could help a tiny amount, I didn't want to change the code because
a separate translation unit for the CRC tables was needed for the
x86 assembly code anyway. But when visibility attributes are
supported, simply marking the extern declaration with the
hidden attribute will get identical result. When there are only
a few affected variables, this is trivial to do. I wish I had
understood this back then already.
MinGW (formely a MinGW.org Project, later the MinGW.OSDN Project
at <https://osdn.net/projects/mingw/>) has GCC 9.2.0 as the
most recent GCC package (released 2021-02-02). The project might
still be alive but majority of people have switched to MinGW-w64.
Thus it seems clearer to refer to MinGW-w64 in our API headers too.
Building with MinGW is likely to still work but I haven't tested it
in the recent years.
A CMake option LARGE_FILE_SUPPORT is created if and only if
-D_FILE_OFFSET_BITS=64 affects sizeof(off_t).
This is needed on many 32-bit platforms and even with 64-bit builds
with MinGW-w64 to get support for files larger than 2 GiB.
Autotools based build uses -pthread and thus adds it to Libs.private
in liblzma.pc. CMake doesn't use -pthread at all if pthread functions
are available in libc so Libs.private doesn't get -pthread either.
It properly adds -DLZMA_API_STATIC when compiling code that
will be linked against static liblzma. Having it there on
systems other than Windows does no harm.
See: https://www.msys2.org/docs/pkgconfig/
Using set(ENABLE_THREADS "posix") is confusing because it sets
a new normal variable and leaves the cache entry with the same
name unchanged. The intent wasn't to change the cache entry so
this switches to a different variable name.
This way typos are caught quickly and compounding error messages
are avoided (a single typo could cause more than one error).
This keeps using SEND_ERROR when the system is lacking a feature
(like threading library or sandboxing method). This way the whole
configuration log will be generated in case someone wishes to
report a problem upstream.
The option is enabled by default, but will only be visible to a user
listing cache variables or using a CMake GUI application if the
immintrin.h header file is found.
This mirrors our Autotools build --disable-clmul-crc functionality.
In XZ Utils context this doesn't matter much because
unaligned reads and writes aren't used in hot code
when TUKLIB_FAST_UNALIGNED_ACCESS isn't #defined.
The Ninja Generator for CMake cannot have a custom target and its
BYPRODUCTS have the same name. This has prevented Ninja builds on
Unix-like systems since the xz symlinks were introduced in
80a1a8bb83.
Lasse Collin
Jia Tan
Kian-Meng Ang