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)
Clang 17 with -fsanitize=address,undefined:
src/liblzma/common/filter_common.c:366:8: runtime error:
call to function encoder_find through pointer to incorrect
function type 'const lzma_filter_coder *(*)(unsigned long)'
src/liblzma/common/filter_encoder.c:187: note:
encoder_find defined here
Use a wrapper function to get the correct type neatly.
This reduces the number of casts needed too.
This issue could be a problem with control flow integrity (CFI)
methods that check the function type on indirect function calls.
Fixes: 3b34851de1
(cherry picked from commit 278563ef8f)
It's undefined behavior. The result wasn't ever used as it occurred
in the last iteration of a loop.
Clang 17 with -fsanitize=address,undefined:
$ src/xz/xz --block-list=123
src/xz/args.c:164:12: runtime error: applying non-zero offset 1
to null pointer
Fixes: 88ccf47205
Co-authored-by: Sam James <sam@gentoo.org>
(cherry picked from commit 77c8f60547)
If the arguments to lzma_index_decoder() or lzma_index_buffer_decode()
were such that LZMA_PROG_ERROR was returned, the lzma_index **i
argument wasn't touched even though the API docs say that *i = NULL
is done if an error occurs. This obviously won't be done even now
if i == NULL but otherwise it is best to do it due to the wording
in the API docs.
In practice this matters very little: The problem can occur only
if the functions are called with invalid arguments, that is,
the calling application must already have a bug.
(cherry picked from commit 71eed2520e)
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)
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 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.
(This commit was contributed under 0BSD but the author confirmed
that it is fine to backport it to the public domain branches. See
https://github.com/tukaani-project/xz/pull/90#issuecomment-2100185936
and the next two messages.)
(cherry picked from commit 096bc0e3f8)
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.
(cherry picked from commit c701a5909a)
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.
(cherry picked from commit 76946dc433)
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.
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.
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.
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/
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.
When the generic fast crc64 method is used, then we omit
lzma_crc64_table[][].
The C standards don't allow an empty translation unit which can be
avoided by declaring something, without exporting any symbols.
Before this commit, the following writes "foo" to the
console and deletes the input file:
echo foo | xz > con_xz
xz --suffix=_xz --decompress con_xz
It cannot happen without --suffix because names like con.xz
are also special and so attempting to decompress con.xz
(or compress con to con.xz) will already fail when opening
the input file.
Similar thing is possible when compressing. The following
writes to "nul" and the input file "n" is deleted.
echo foo | xz > n
xz --suffix=ul n
Now xz checks if the destination is a special file before
continuing. DOS/DJGPP version had a check for this but
Windows (and OS/2) didn't.
Lasse Collin
Sergey Kosukhin
Jia Tan