The __builtin_bswapXX from GCC and Clang are preferred when
they are available. This can allow compilers to emit the x86 MOVBE
instruction instead of doing a load + byteswap as two instructions
(which would happen if the byteswapping is done in inline asm).
bswap16, bswap32, and bswap64 exist in system headers on *BSDs
and Darwin. #defining bswap16 on NetBSD results in a warning about
macro redefinition. It's safest to avoid this namespace conflict
completely.
No OS supported by tuklib_integer.h uses byteswapXX names and
a web search doesn't immediately find any obvious danger of
namespace conflicts. So let's try these still-pretty-short names
for the macros.
Thanks to Sam James for pointing out the compiler warning on
NetBSD 10.0.
(cherry picked from commit 4ffc60f323)
The API docs clearly say that if error_pos isn't NULL then *error
is always set on any error. However, it wasn't touched if str == NULL
or filters == NULL or unsupported flags were specified.
Fixes: cedeeca2ea
(cherry picked from commit 70d12dd069)
It is logical why it cannot know for sure that the value has
to be at most 4 if it is less than 16.
The x86 filter is based on a very old LZMA SDK version. Newer
ones have quite a different implementation for the same filter.
Thanks to Sam James.
(cherry picked from commit 6aa2a6deeb)
On macOS, we get:
```
signals.c: In function 'signals_init':
signals.c:76:17: error: conversion to 'sigset_t' {aka 'unsigned int'} from 'int' may change the sign of the result [-Werror=sign-conversion]
76 | sigaddset(&hooked_signals, sigs[i]);
| ^~~~~~~~~
signals.c:81:17: error: conversion to 'sigset_t' {aka 'unsigned int'} from 'int' may change the sign of the result [-Werror=sign-conversion]
81 | sigaddset(&hooked_signals, message_progress_sigs[i]);
| ^~~~~~~~~
signals.c:86:9: error: conversion to 'sigset_t' {aka 'unsigned int'} from 'int' may change the sign of the result [-Werror=sign-conversion]
86 | sigaddset(&hooked_signals, SIGTSTP);
| ^~~~~~~~~
```
We use `int` for `hooked_signals` but we can't just cast to whatever
`sigset_t` is because `sigset_t` is an opaque type. It's an unsigned int
on macOS. On macOS, `sigaddset` is implemented as a macro.
Just suppress -Wsign-conversion for `signals_init` for macOS given
there's no real nice way of fixing this.
(cherry picked from commit 863f13d282)
A macro is useful to prevent a single #if directive from
getting too ugly but only one macro is needed for all archs.
(cherry picked from commit 6286c1900c)
This is *NOT* done for security reasons even though the backdoor
relied on the ifunc code. Instead, the reason is that in this
project ifunc provides little benefits but it's quite a bit of
extra code to support it. The only case where ifunc *might* matter
for performance is if the CRC functions are used directly by an
application. In normal compression use it's completely irrelevant.
(cherry picked from commit 689ae24273)
NVHPC compiler has several issues that make it impossible to
build liblzma:
- the compiler cannot handle unions that contain pointers that
are not the first members;
- the compiler cannot handle the assembler code in range_decoder.h
(LZMA_RANGE_DECODER_CONFIG has to be set to zero);
- the compiler fails to produce valid code for delta_decode if the
vectorization is enabled, which results in failed tests.
This introduces NVHPC-specific workarounds that address the issues.
(cherry picked from commit 096bc0e3f8)
While the backdoor was inactive (and thus harmless) without inserting
a small trigger code into the build system when the source package was
created, it's good to remove this anyway:
- The executable payloads were embedded as binary blobs in
the test files. This was a blatant violation of the
Debian Free Software Guidelines.
- On machines that see lots bots poking at the SSH port, the backdoor
noticeably increased CPU load, resulting in degraded user experience
and thus overwhelmingly negative user feedback.
- The maintainer who added the backdoor has disappeared.
- Backdoors are bad for security.
This reverts the following without making any other changes:
6e636819 Tests: Update two test files.
a3a29bbd Tests: Test --single-stream can decompress bad-3-corrupt_lzma2.xz.
0b4ccc91 Tests: Update RISC-V test files.
8c9b8b20 liblzma: Fix typos in crc32_fast.c and crc64_fast.c.
82ecc538 liblzma: Fix false Valgrind error report with GCC.
cf44e4b7 Tests: Add a few test files.
3060e107 Tests: Use smaller dictionary size in RISC-V test files.
e2870db5 Tests: Add two RISC-V Filter test files.
The RISC-V test files also have real content that tests the filter
but the real content would fit into much smaller files. A generator
program would need to be available as well.
Thanks to Andres Freund for finding and reporting it and making
it public quickly so others could act without a delay.
See: https://www.openwall.com/lists/oss-security/2024/03/29/4
With GCC and a certain combination of flags, Valgrind will falsely
trigger an invalid write. This appears to be due to the omission of
instructions to properly save, set up, and restore the frame pointer.
The IFUNC resolver is a leaf function since it only calls a function
that is inlined. So sometimes GCC omits the frame pointer instructions
in the resolver unless this optimization is explictly disabled.
This fixes https://bugzilla.redhat.com/show_bug.cgi?id=2267598.
Now that multi threaded encoding is the default, users do not need to
see a warning message everytime the number of threads is reduced. On
some machines, this could happen very often. It is not unreasonable for
users to need to set double verbose mode to see this kind of
information.
To see these warning messages -vv or --verbose --verbose must be passed
to set xz into the highest possible verbosity mode.
These warnings had caused automated testing frameworks to fail when they
expected no output to stderr.
Thanks to Sebastian Andrzej Siewior for reporting this and for the
initial version of the patch.
The previous Linux Landlock feature test assumed that having the
linux/landlock.h header file was enough. The new feature tests also
requires that prctl() and the required Landlock system calls are
supported.
If xz is given a directory, it should look like this:
$ xz /usr/bin
xz: /usr/bin: Is a directory, skipping
The Landlock rules didn't allow opening directories for reading:
$ xz /usr/bin
xz: /usr/bin: Permission denied
The simplest fix was to allow opening directories for reading.
While it's a bit silly to allow it solely for the error message,
it shouldn't make the sandbox significantly weaker.
The single-file use case (like when called from GNU tar) is
still as strict as possible: all Landlock restrictions are
enabled before (de)compression starts.
This makes these sandboxing methods stricter when no files are
created or deleted. That is, it's a middle ground between the
initial sandbox and the strictest single-file-to-stdout sandbox:
this allows opening files for reading but output has to go to stdout.
Linux 6.7 added support for ABI version 4 which restricts
TCP connections which xz won't need and thus those can be
forbidden now. Since the ABI version is handled at runtime,
supporting version 4 won't cause any compatibility issues.
Note that new enough kernel headers are required to get
version 4 support enabled at build time.
Landlock is now always used just like pledge(2) is: first in more
permissive mode and later (under certain common conditions) in
a strict mode that doesn't allow opening more files.
I put pledge(2) first in sandbox.c because it's the simplest API
to use and still somewhat fine-grained for basic applications.
So it's the simplest thing to understand for anyone reading sandbox.c.
Also explicitly initialize progress_automatic to make it clear
that it can be read before message_init() sets it. Static variable
was initialized to false by default already so this is only for
clarity.
GCC docs promise that it works and a few other compilers do
too. Clang/LLVM is documented source code only but unsurprisingly
it behaves the same as others on x86-64 at least. But the
certainly-portable way is good enough here so use that.
The x32 port has a x86-64 ABI in term of all registers but uses only
32bit pointer like x86-32. The assembly optimisation fails to compile on
x32. Given the state of x32 I suggest to exclude it from the
optimisation rather than trying to fix it.
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
It's used only for basic bittrees and fixed-size reverse bittree
because those showed a clear benefit on x86-64 with GCC and Clang.
The other methods were more mixed and thus are commented out but
they should be tested on other archs.
Now extra buffer space is reserved so that repeating bytes for
any single match will never need to copy from two places (both
the beginning and the end of the buffer). This simplifies
dict_repeat() and helps a little with speed.
This seems to reduce .lzma decompression time about 2 %, so
with .xz and CRC it could be slightly less. The small things
add up still.
It's not completely obvious if this is better in the decoder.
It should be good if compiler can avoid creating a branch
(like using CMOV on x86).
This also makes lzma_encoder.c use the new macros.
The new decoder resumes the first decoder loop in the Resumable mode.
Then, the code executes in Non-resumable mode until it detects that it
cannot guarantee to have enough input/output to decode another symbol.
The Resumable mode is how the decoder has always worked. Before decoding
every input bit, it checks if there is enough space and will save its
location to be resumed later. When the decoder has more input/output,
it jumps back to the correct sequence in the Resumable mode code.
When the input/output buffers are large, the Resumable mode is much
slower than the Non-resumable because it has more branches and is harder
for the compiler to optimize since it is in a large switch block.
Early benchmarking shows significant time improvement (8-10% on gcc and
clang x86) by using the Non-resumable code as much as possible.
The new "safe" range decoder mode is the same as old range decoder, but
now the default behavior of the range decoder will not check if there is
enough input or output to complete the operation. When the buffers are
close to fully consumed, the "safe" operations must be used instead. This
will improve speed because it will reduce the number of branches needed
for most of the range decoder operations.
The main reason is a kind of silly one:
xz-man.pot contains strings from all man pages in XZ Utils.
The man pages of xzdiff, xzgrep, and xzmore were under GPLv2
and the rest under 0BSD. Thus xz-man.pot contained strings
under two licences. po4a creates the translated man pages
from the combined 0BSD+GPLv2 xz-man.pot.
I haven't liked this mixing in xz-man.pot but the
Translation Project requires that all man pages must be
in the same .pot file. So a separate xz-man-gpl.pot
wasn't an option.
Since these man pages are short, rewriting them was quick enough.
Now xz-man.pot is entirely under 0BSD and marking the per-file
licenses is simpler.
As a bonus, some wording hopefully is now slightly better
although it's perhaps a matter of taste.
NOTE: In xzgrep.1, the EXIT STATUS section was written by me
in the commit d796b6d7fd so that's
why that section could be taken as is from the old xzgrep.1.
Perhaps the generated files aren't even copyrightable but
using the same license for them as for the rest of the liblzma
keeps things more consistent for tools that look for license info.
The initial commit 5d018dc035
in 2007 had a comment in sha256.c that the code is based on
Crypto++ Library 5.5.1. In 2009 the Authors list in sha256.c
and the AUTHORS file was updated with information that the
code had come from Crypto++ but via 7-Zip. I know I had viewed
7-Zip's SHA-256 code but back then the C code has been identical
enough with Crypto++, so I don't why I thought the author info
would need that extra step via 7-Zip for this single file.
Another error is that I had mixed sha.* and shacal2.* files
when checking for author info in Crypto++. The shacal2.* files
aren't related to liblzma's sha256.c and thus Kevin Springle's
code in Crypto++ isn't either.
If liblzma is configured with --disable-clmul-crc
CFLAGS="-msse4.1 -mpclmul", then it will fail to compile because the
generic version must be used but the CRC tables were not included.
The code was using HAVE_FUNC_ATTRIBUTE_IFUNC instead of CRC_USE_IFUNC.
With ARM64, ifunc is incompatible because it requires non-inline
function calls for runtime detection.
Even though the proper name for the architecture is aarch64, this
project uses ARM64 throughout. So the rename is for consistency.
Additionally, crc32_arm64.h was slightly refactored for the following
changes:
* Added MSVC, FreeBSD, and macOS support in
is_arch_extension_supported().
* crc32_arch_optimized() now checks the size when aligning the
buffer.
* crc32_arch_optimized() loop conditions were slightly modified to
avoid both decrementing the size and incrementing the buffer
pointer.
* Use the intrinsic wrappers defined in <arm_acle.h> because GCC and
Clang name them differently.
* Minor spacing and comment changes.
The CRC_GENERIC is now split into CRC32_GENERIC and CRC64_GENERIC, since
the ARM64 optimizations will be different between CRC32 and CRC64.
For the same reason, CRC_ARCH_OPTIMIZED is split into
CRC32_ARCH_OPTIMIZED and CRC64_ARCH_OPTIMIZED.
ifunc will only be used with x86-64 CLMUL because the runtime detection
methods needed with ARM64 are not compatible with ifunc.
The CRC32 instructions in ARM64 can calculate the CRC32 result
for 8 bytes in a single operation, making the use of ARM64
instructions much faster compared to the general CRC32 algorithm.
Optimized CRC32 will be enabled if ARM64 has CRC extension
running on Linux.
Signed-off-by: Chenxi Mao <chenxi.mao2013@gmail.com>
This hopefully does more good than bad:
+ It's faster by default.
+ Only the threaded compressor creates files that
can be decompressed in threaded mode.
- Compression ratio is worse, usually not too much though.
When it matters, -T1 must be used.
- Memory usage increases.
- Scripts that assume single-threaded mode but don't use -T1 will
possibly use too much resources, for example, if they run
multiple xz processes in parallel to compress multiple files.
- Output from single-threaded and multi-threaded compressors
differ but such changes could happen for other reasons too
(they just haven't happened since 5.0.0).
Not all RISC-V processors support fast unaligned access so
it's better to read only one byte in the main loop. This can
be faster even on x86-64 when compared to reading 32 bits at
a time as half the time the address is only 16-bit aligned.
The downside is larger code size on archs that do support
fast unaligned access.
Version 5.6.0 will be shown, even though upcoming alphas and betas
will be able to support this filter. 5.6.0 looks nicer in the output and
people shouldn't be encouraged to use an unstable version in production
in any way.
Lasse Collin
Sam James
Sergey Kosukhin
Jia Tan
Chien Wong
Sebastian Andrzej Siewior
Chenxi Mao