The C standards don't allow an empty translation unit which can be
avoided by declaring something, without exporting any symbols.
When I committed f644473a21 I had
a feeling that some specific toolchain somewhere didn't like
empty object files (assembler or maybe "ar" complained) but
I cannot find anything to confirm this now. Quite likely I
remembered nonsense. I leave this here as a note to my future self. :-)
When the generic fast crc64 method is used, then we omit
lzma_crc64_table[][]. Similar to
d9166b52cf, we can avoid compiler warnings
with -Wempty-translation-unit (Clang) or -pedantic (GCC) by creating a
never used typedef instead of an extra symbol.
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.
For compatibility with C23's [[noreturn]], tuklib_attr_noreturn
must be at the beginning of declaration (before "extern" or
"static", and even before any GNU C's __attribute__).
This commit also moves all other function attributes to
the beginning of function declarations. "extern" is kept
at the beginning of a line so the attributes are listed on
separate lines before "extern" or "static".
xrealloc() is obviously incorrect, modern GCC docs even
mention realloc() as an example where this attribute
cannot be used.
liblzma's lzma_alloc() and lzma_alloc_zero() would be
correct uses most of the time but custom allocators
may use a memory pool or otherwise hold the pointer
so aliasing issues could happen in theory.
The xstrdup() case likely was correct but I removed it anyway.
Now there are no __malloc__ attributes left in the code.
The allocations aren't in hot paths so this should make
no practical difference.
This makes no difference for GCC or Clang as they support
GNU C's __attribute__((__noreturn__)) but this helps with MSVC:
- VS 2019 version 16.7 and later support _Noreturn if the
options /std:c11 or /std:c17 are used. This gets handled
with the check for __STDC_VERSION__ >= 201112.
- When MSVC isn't in C11/C17 mode, __declspec(noreturn) is used.
C23 will deprecate _Noreturn (and <stdnoreturn.h>)
for [[noreturn]]. This commit anticipates that but
the final __STDC_VERSION__ value isn't known yet.
Now the two variations of the format strings are created with
a macro, and the whole detection code can be easily disabled
on platforms where thousand separator formatting is known to
not work (MSVC has no support, and on DJGPP 2.05 it can have
problems in some cases).
The argument to vli_ceil4() should always guarantee the return value
is also a valid lzma_vli. Thus the highest three valid lzma_vli values
are invalid arguments. All uses of the function ensure this so the
assert is updated to match this.
This was not a security bug since there was no path to overflow
UINT64_MAX in lzma_index_append() or when it calls index_file_size().
The bug was discovered by a failing assert() in vli_ceil4() when called
from index_file_size() when unpadded_sum (the sum of the compressed size
of current Stream and the unpadded_size parameter) exceeds LZMA_VLI_MAX.
Previously, the unpadded_size parameter was checked to be not greater
than UNPADDED_SIZE_MAX, but no check was done once compressed_base was
added.
This could not have caused an integer overflow in index_file_size() when
called by lzma_index_append(). The calculation for file_size breaks down
into the sum of:
- Compressed base from all previous Streams
- 2 * LZMA_STREAM_HEADER_SIZE (size of the current Streams header and
footer)
- stream_padding (can be set by lzma_index_stream_padding())
- Compressed base from the current Stream
- Unpadded size (parameter to lzma_index_append())
The sum of everything except for Unpadded size must be less than
LZMA_VLI_MAX. This is guarenteed by overflow checks in the functions
that can set these values including lzma_index_stream_padding(),
lzma_index_append(), and lzma_index_cat(). The maximum value for
Unpadded size is enforced by lzma_index_append() to be less than or
equal UNPADDED_SIZE_MAX. Thus, the sum cannot exceed UINT64_MAX since
LZMA_VLI_MAX is half of UINT64_MAX.
Thanks to Joona Kannisto for reporting this.
The "once_" variable was accidentally referred to as just "once". This
prevented building with Vista threads when
HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR was not defined.
signal.h in WASI SDK doesn't currently provide sigprocmask()
or sigset_t. liblzma doesn't need them so this change makes
liblzma and xzdec build against WASI SDK. xz doesn't build yet
and the tests don't either as tuktest needs setjmp() which
isn't (yet?) implemented in WASI SDK.
Closes: https://github.com/tukaani-project/xz/pull/57
See also: https://github.com/tukaani-project/xz/pull/56
(The original commit was edited a little by Lasse Collin.)
To workaround Automake lacking Windows resource compiler support, an
empty source file is compiled to overwrite the resource files for static
library builds. Translation units without an external declaration are
not allowed by the C standard and result in a warning when used with
-Wempty-translation-unit (Clang) or -pedantic (GCC).
Clang 16.0.0 and earlier have a bug that the ifunc resolver function
triggers the -Wunused-function warning. The resolver function is static
and only "used" by the __attribute__((__ifunc()__)).
At this time, the bug is still unresolved, but has been reported:
https://github.com/llvm/llvm-project/issues/63957
This is not a problem in GCC.
This further improves the documentation from commit
f36ca7982f. The previous wording of
"supported options" was slightly misleading since the options that are
printed are the ones that are relevant for encoding/decoding. It is not
about which options can or must be specified.
The Memory limit information section described three output
columns when it actually has six. This was reworded to
"multiple" to make it more future proof.
* Moved max_block_list_size from a global to local variable.
* Reworded error message in validate_block_list_filter().
* Removed helper function filter_chain_error().
* Changed 1 << X to 1U << X in many places
The order is now consistent with the order the command line arguments
are documented earlier in the man page. The new order is:
1. --list
2. --info-memory
3. --version
Instead of the previous order:
1. --version
2. --info-memory
3. --list
The --filters-help can be used to help create filter chains with the
--filters and --filtersX options. The message in --long-help is too
short to fully explain the syntax to construct complex filter chains.
In --robot mode, xz will only print the output from liblzma function
lzma_str_list_filters.
The --block-list option description needed updating since the new
--filtersX option changes how it can be used. The new entry for
--filters1=FILTERS ... --filter9=FILTERS was created right after
the --filters option.
If a filter chain is set but not used in --block-list, it introduced
unexpected behavior such as requiring an unneeded amount of memory to
compress, reducing the number of threads in multi-threaded encoding, and
printing an incorrect amount of memory needed to decompress.
This also renames filters_init_mask => filters_used_mask. A filter is
assumed to be used if it is specified in --filtersX until
coder_set_compression_settings() determines which filters are referenced
in --block-list.
When opt_block_size is not used, the Block size for mt encoder is
derived from the minimum of the largest Block specified by
--block-list and the recommended Block size on all filter chains
calculated by lzma_mt_block_size(). This avoids using unnecessary
memory and ensures that all Blocks are large enough for the most memory
needy filter chain.
Lasse Collin
Jia Tan
Kelvin Lee
Jamaika1
ChanTsune
Dimitri Papadopoulos Orfanos