Commit Graph

658 Commits

Author SHA1 Message Date
Lasse Collin 12c90c00f0 liblzma: Check also for __clang__ in memcmplen.h.
This change hopefully makes no practical difference as Clang
likely was detected via __GNUC__ or _MSC_VER already.
2023-12-28 17:17:39 +02:00
Jia Tan b34b6a9912 liblzma: Initialize lzma_lz_encoder pointers with NULL.
This fixes the recent change to lzma_lz_encoder that used memzero
instead of the NULL constant. On some compilers the NULL constant
(always 0) may not equal the NULL pointer (this only needs to guarentee
to not point to valid memory address).

Later code compares the pointers to the NULL pointer so we must
initialize them with the NULL pointer instead of 0 to guarentee
code correctness.
2023-12-20 21:38:39 +08:00
Jia Tan 183a62f0b5 liblzma: Set all values in lzma_lz_encoder to NULL after allocation.
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.

This is fixed by using memzero() to set all members of lzma_lz_encoder
to NULL after it is allocated. This ensures this mistake will not occur
here in the future if any additional function pointers are added.
2023-12-16 20:51:38 +08:00
Jia Tan 1a1bb381db liblzma: Tweak a comment. 2023-12-16 20:30:55 +08:00
Jia Tan 55810780e0 liblzma: Make parameter names in function definition match declaration.
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.
2023-12-16 20:28:21 +08:00
Jia Tan 5dad6f628a liblzma: Improve lzma encoder init function consistency.
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.
2023-12-16 20:18:47 +08:00
Jia Tan 2ade7246e7 liblzma: Add missing comments to lz_encoder.h. 2023-11-09 01:21:53 +08:00
Lasse Collin 46007049cd liblzma: Fix compilation of fastpos_tablegen.c.
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.
2023-10-31 21:41:09 +02:00
Lasse Collin 8c36ab79cb liblzma: Add a note why crc_always_inline exists for now.
Solaris Studio is a possible example (not tested) which
supports the always_inline attribute but might not get
detected by the common.h #ifdefs.
2023-10-30 18:44:32 +02:00
Lasse Collin e7a86b94cd liblzma: Use lzma_always_inline in memcmplen.h. 2023-10-30 18:44:32 +02:00
Lasse Collin dcfe563299 liblzma: #define lzma_always_inline in common.h. 2023-10-30 18:44:32 +02:00
Lasse Collin 41113fe30a liblzma: Use lzma_attr_visibility_hidden on private extern declarations.
These variables are internal to liblzma and not exposed in the API.
2023-10-30 18:06:25 +02:00
Lasse Collin a2f5ca706a liblzma: #define lzma_attr_visibility_hidden in common.h.
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.
2023-10-30 18:03:39 +02:00
Lasse Collin 2c7ee92e44 liblzma: Refer to MinGW-w64 instead of MinGW in the API headers.
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.
2023-10-26 21:46:06 +03:00
Lasse Collin a7d1b2825c liblzma: Add Cflags.private to liblzma.pc.in for MSYS2.
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/
2023-10-26 21:46:06 +03:00
Jia Tan 988e09f27b liblzma: Move is_clmul_supported() back to crc_common.h.
This partially reverts creating crc_clmul.c
(8c0f9376f5) where is_clmul_supported()
was moved, extern'ed, and renamed to lzma_is_clmul_supported(). This
caused a problem when the function call to lzma_is_clmul_supported()
results in a call through the PLT. ifunc resolvers run very early in
the dynamic loading sequence, so the PLT may not be setup properly at
this point. Whether the PLT is used or not for
lzma_is_clmul_supported() depened upon the compiler-toolchain used and
flags.

In liblzma compiled with GCC, for instance, GCC will go through the PLT
for function calls internal to liblzma if the version scripts and
symbol visibility hiding are not used. If lazy-binding is disabled,
then it would have made any program linked with liblzma fail during
dynamic loading in the ifunc resolver.
2023-10-21 00:01:29 +08:00
Jia Tan 105c7ca90d Build: Remove check for COND_CHECK_CRC32 in check/Makefile.inc.
Currently crc32 is always enabled, so COND_CHECK_CRC32 must always be
set. Because of this, it makes the recent change to conditionally
compile check/crc_clmul.c appear wrong since that file has CLMUL
implementations for both CRC32 and CRC64.
2023-10-19 16:23:32 +08:00
Jia Tan c60b25569d liblzma: Fix -fsanitize=address failure with crc_clmul functions.
After forcing crc_simd_body() to always be inlined it caused
-fsanitize=address to fail for lzma_crc32_clmul() and
lzma_crc64_clmul(). The __no_sanitize_address__ attribute was added
to lzma_crc32_clmul() and lzma_crc64_clmul(), but not removed from
crc_simd_body(). ASAN and inline functions behavior has changed over
the years for GCC specifically, so while strictly required we will
keep __attribute__((__no_sanitize_address__)) on crc_simd_body() in
case this becomes a requirement in the future.

Older GCC versions refuse to inline a function with ASAN if the
caller and callee do not agree on sanitization flags
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89124#c3). If the
function was forced to be inlined, it will not compile if the callee
function has __no_sanitize_address__ but the caller doesn't.
2023-10-19 01:15:20 +08:00
Jia Tan 1c8884f0af liblzma: Set the MSVC optimization fix to only cover lzma_crc64_clmul().
After testing a 32-bit Release build on MSVC, only lzma_crc64_clmul()
has the bug. crc_simd_body() and lzma_crc32_clmul() do not need the
optimizations disabled.
2023-10-18 23:54:41 +08:00
Lasse Collin 5ce0f7a48b liblzma: CRC_USE_GENERIC_FOR_SMALL_INPUTS cannot be used with ifunc. 2023-10-18 23:54:41 +08:00
Lasse Collin 2773538049 liblzma: Include common.h in crc_common.h.
crc_common.h depends on common.h. The headers include common.h except
when there is a reason to not do so.
2023-10-18 23:54:41 +08:00
Jia Tan e13b7947b9 liblzma: Add include guards to crc_common.h. 2023-10-18 23:54:41 +08:00
Jia Tan 40abd88afc liblzma: Add the crc_always_inline macro to crc_simd_body().
Forcing this to be inline has a significant speed improvement at the
cost of a few repeated instructions. The compilers tested on did not
inline this function since it is large and is used twice in the same
translation unit.
2023-10-18 23:54:41 +08:00
Jia Tan a5966c276b liblzma: Create crc_always_inline macro.
This macro must be used instead of the inline keyword. On MSVC, it is
a replacement for __forceinline which is an MSVC specific keyword that
should not be used with inline (it will issue a warning if it is).

It does not use a build system check to determine if
__attribute__((__always_inline__)) since all compilers that can use
CLMUL extensions (except the special case for MSVC) should support this
attribute. If this assumption is incorrect then it will result in a bug
report instead of silently producing slow code.
2023-10-18 23:54:41 +08:00
Jia Tan 96b663f67c liblzma: Refactor CRC comments.
A detailed description of the three dispatch methods was added. Also,
duplicated comments now only appear in crc32_fast.c or were removed from
both crc32_fast.c and crc64_fast.c if they appeared in crc_clmul.c.
2023-10-18 23:54:41 +08:00
Jia Tan 8c0f9376f5 liblzma: Create crc_clmul.c.
Both crc32_clmul() and crc64_clmul() are now exported from
crc32_clmul.c as lzma_crc32_clmul() and lzma_crc64_clmul(). This
ensures that is_clmul_supported() (now lzma_is_clmul_supported()) is
not duplicated between crc32_fast.c and crc64_fast.c.

Also, it encapsulates the complexity of the CLMUL implementations into a
single file and reduces the complexity of crc32_fast.c and crc64_fast.c.
Before, CLMUL code was present in crc32_fast.c, crc64_fast.c, and
crc_common.h.

During the conversion, various cleanups were applied to code (thanks to
Lasse Collin) including:

- Require using semicolons with MASK_/L/H/LH macros.
- Variable typing and const handling improvements.
- Improvements to comments.
- Fixes to the pragmas used.
- Removed unneeded variables.
- Whitespace improvements.
- Fixed CRC_USE_GENERIC_FOR_SMALL_INPUTS handling.
- Silenced warnings and removed the need for some #pragmas
2023-10-18 23:54:36 +08:00
Jia Tan a3ebc2c516 liblzma: Define CRC_USE_IFUNC in crc_common.h.
When ifunc is supported, we can define a simpler macro instead of
repeating the more complex check in both crc32_fast.c and crc64_fast.c.
2023-10-18 20:41:11 +08:00
Hans Jansen f1cd9d7194 liblzma: Added crc32_clmul to crc32_fast.c. 2023-10-13 20:54:05 +08:00
Hans Jansen 93e6fb08b2 liblzma: Moved CLMUL CRC logic to crc_common.h.
crc64_fast.c was updated to use the code from crc_common.h instead.
2023-10-13 20:54:05 +08:00
Hans Jansen 233885a437 liblzma: Rename crc_macros.h to crc_common.h. 2023-10-13 20:54:05 +08:00
Lasse Collin 5a9af95f85 liblzma: Update a comment.
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. :-)
2023-09-26 21:47:13 +03:00
Jia Tan 8ebaf3f665 liblzma: Avoid compiler warning without creating extra symbol.
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.
2023-09-27 00:04:40 +08:00
Jia Tan f6667702bf liblzma: Change quoting style from `...' to '...'.
This was done for both internal and API headers.
2023-09-24 22:09:47 +08:00
Lasse Collin ee7709bae5 liblzma: Move a few __attribute__ uses in function declarations.
The API headers have many attributes but these were left
as is for now.
2023-09-22 20:06:27 +03:00
Lasse Collin 18a66fbac0 Remove incorrect uses of __attribute__((__malloc__)).
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.
2023-09-22 20:06:27 +03:00
Lasse Collin 4f44ef8675 liblzma: Mark crc64_clmul() with __attribute__((__no_sanitize_address__)).
Thanks to Agostino Sarubbo.
Fixes: https://github.com/tukaani-project/xz/issues/62
2023-09-14 16:34:07 +03:00
Jia Tan 721e3d9f7a liblzma: Update assert in vli_ceil4().
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.
2023-08-28 23:05:34 +08:00
Jia Tan ae5c07b22a liblzma: Add overflow check for Unpadded size in lzma_index_append().
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.
2023-08-28 23:04:56 +08:00
Dimitri Papadopoulos Orfanos 42df7c7aa1
Docs: Fix typos found by codespell 2023-07-31 20:02:21 +08:00
Jia Tan d9166b52cf liblzma: Prevent an empty translation unit in Windows builds.
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).
2023-07-24 23:11:13 +08:00
Jia Tan 0184d344fa liblzma: Suppress -Wunused-function warning.
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.
2023-07-19 23:36:00 +08:00
Jia Tan 43845fa70f liblzma: Reword lzma_str_list_filters() documentation.
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.
2023-07-18 22:57:58 +08:00
Jia Tan 818701ba1c liblzma: Improve comment in string_conversion.c.
The comment used "flag" when referring to decoder options. Just
referring to them as options is more clear and consistent.
2023-07-18 22:56:47 +08:00
Lasse Collin 97fd5cb669 liblzma: Tweak #if condition in memcmplen.h.
Maybe ICC always #defines _MSC_VER on Windows but now
it's very clear which code will get used.
2023-07-18 13:57:54 +03:00
Lasse Collin 40392c19f7 liblzma: Omit unnecessary parenthesis in a preprocessor directive. 2023-07-18 13:49:43 +03:00
Jia Tan 17f8844e6f liblzma: Remove non-portable empty initializer.
Commit 78704f36e7 added an empty
initializer {} to prevent a warning. The empty initializer is a GNU
extension and results in a build failure on MSVC. The -wpedantic flag
warns about empty initializers.
2023-07-08 21:24:19 +08:00
Jia Tan 78704f36e7 liblzma: Prevent uninitialzed warning in mt stream encoder.
This change only impacts the compiler warning since it was impossible
for the wait_abs struct in stream_encode_mt() to be used before it was
initialized since mythread_condtime_set() will always be called before
mythread_cond_timedwait().

Since the mythread.h code is different between the POSIX and
Windows versions, this warning was only present on Windows builds.

Thanks to Arthur S for reporting the warning and providing an initial
patch.
2023-06-29 00:06:16 +08:00
Jia Tan e3356a204c liblzma: Prevent warning for MSYS2 Windows build.
In lzma_memcmplen(), the <intrin.h> header file is only included if
_MSC_VER and _M_X64 are both defined but _BitScanForward64() was
previously used if _M_X64 was defined. GCC for MSYS2 defines _M_X64 but
not _MSC_VER so _BitScanForward64() was used without including
<intrin.h>.

Now, lzma_memcmplen() will use __builtin_ctzll() for MSYS2 GCC builds as
expected.
2023-06-28 23:59:51 +08:00
Lasse Collin ee44863ae8 liblzma: Add ifunc implementation to crc64_fast.c.
The ifunc method avoids indirection via the function pointer
crc64_func. This works on GNU/Linux and probably on FreeBSD too.
The previous __attribute((__constructor__)) method is kept for
compatibility with ELF platforms which do support ifunc.

The ifunc method has some limitations, for example, building
liblzma with -fsanitize=address will result in segfaults.
The configure option --disable-ifunc must be used for such builds.

Thanks to Hans Jansen for the original patch.
Closes: https://github.com/tukaani-project/xz/pull/53
2023-06-27 23:55:59 +08:00
Jia Tan f36ca7982f liblzma: Slightly rewords lzma_str_list_filters() documentation.
Reword "options required" to "supported options". The previous may have
suggested that the options listed were all required anytime a filter is
used for encoding or decoding. The reword makes this more clear that
adjusting the options is optional.
2023-05-13 21:21:54 +08:00
Jia Tan 3374a5359e liblzma: Adds lzma_nothrow to MicroLZMA API functions.
None of the liblzma functions may throw an exception, so this
attribute should be applied to all liblzma API functions.
2023-05-12 00:00:47 +08:00
Jia Tan 8f23657498 liblzma: Exports lzma_mt_block_size() as an API function.
The lzma_mt_block_size() was previously just an internal function for
the multithreaded .xz encoder. It is used to provide a recommended Block
size for a given filter chain.

This function is helpful to determine the maximum Block size for the
multithreaded .xz encoder when one wants to change the filters between
blocks. Then, this determined Block size can be provided to
lzma_stream_encoder_mt() in the lzma_mt options parameter when
intializing the coder. This requires one to know all the filter chains
they are using before starting to encode (or at least the filter chain
that will need the largest Block size), but that isn't a bad limitation.
2023-05-11 23:54:44 +08:00
Jia Tan d0f33d672a liblzma: Creates IS_ENC_DICT_SIZE_VALID() macro.
This creates an internal liblzma macro to test if the dictionary size
is valid for encoding.
2023-05-11 22:28:45 +08:00
Jia Tan f41df2ac2f Windows: Include <intrin.h> when needed.
Legacy Windows did not need to #include <intrin.h> to use the MSVC
intrinsics. Newer versions likely just issue a warning, but the MSVC
documentation says to include the header file for the intrinsics we use.

GCC and Clang can "pretend" to be MSVC on Windows, so extra checks are
needed in tuklib_integer.h to only include <intrin.h> when it will is
actually needed.
2023-04-19 22:22:16 +08:00
Lasse Collin 3938718ce3 liblzma: Update project maintainers in lzma.h.
AUTHORS was updated earlier, lzma.h was simply forgotten.
2023-04-14 18:42:33 +03:00
Jia Tan 2a89670ab2 liblzma: Cleans up old commented out code. 2023-04-13 20:45:19 +08:00
Jia Tan 116e81f002 Build: Removes redundant check for LZMA1 filter support. 2023-03-23 21:48:52 +08:00
Lasse Collin dfe1710784 liblzma: Silence -Wsign-conversion in SSE2 code in memcmplen.h.
Thanks to Christian Hesse for reporting the issue.
Fixes: https://github.com/tukaani-project/xz/issues/44
2023-03-19 22:45:59 +02:00
Lasse Collin b473a92891 Change a few HTTP URLs to HTTPS.
The xz man page timestamp was intentionally left unchanged.
2023-03-18 15:56:07 +02:00
Jia Tan fd90e2f4c2 liblzma: Remove note from lzma_options_bcj about the ARM64 exception.
This was left in by mistake since an early version of the ARM64 filter
used a different struct for its options.
2023-03-17 01:42:28 +08:00
Jia Tan 55ba6e9300 liblzma: Add set lzma.h as the main page for Doxygen documentation.
The \mainpage command is used in the first block of comments in lzma.h.
This changes the previously nearly empty index.html to use the first
comment block in lzma.h for its contents.

lzma.h is no longer documented separately, but this is for the better
since lzma.h only defined a few macros that users do not need to use.
The individual API header files all have a disclaimer that they should
not be #included directly, so there should be no confusion on the fact
that lzma.h should be the only header used by applications.

Additionally, the note "See ../lzma.h for information about liblzma as
a whole." was removed since lzma.h is now the main page of the
generated HTML and does not have its own page anymore. So it would be
confusing in the HTML version and was only a "nice to have" when
browsing the source files.
2023-03-17 01:42:28 +08:00
Jia Tan af55191102 liblzma: Defines masks for return values from lzma_index_checks(). 2023-03-13 20:49:53 +08:00
Jia Tan f1ab1f6b33 liblzma: Clarify lzma_lzma_preset() documentation in lzma12.h.
lzma_lzma_preset() does not guarentee that the lzma_options_lzma are
usable in an encoder even if it returns false (success). If liblzma
is built with default configurations, then the options will always be
usable. However if the match finders hc3, hc4, or bt4 are disabled, then
the options may not be usable depending on the preset level requested.

The documentation was updated to reflect this complexity, since this
behavior was unclear before.
2023-03-01 21:42:31 +08:00
Jia Tan 3cf72c4bcb liblzma: Replace '\n' -> newline in filter.h documentation.
The '\n' renders as a newline when the comments are converted to html
by Doxygen.
2023-02-24 21:09:39 +08:00
Jia Tan 002006be62 liblzma: Shorten return description for two functions in filter.h.
Shorten the description for lzma_raw_encoder_memusage() and
lzma_raw_decoder_memusage().
2023-02-24 21:09:39 +08:00
Jia Tan 463d9359b8 liblzma: Reword a few lines in filter.h 2023-02-24 21:09:39 +08:00
Jia Tan 01441df92c liblzma: Improve documentation in filter.h.
All functions now explicitly specify parameter and return values.
The notes and code annotations were moved before the parameter and
return value descriptions for consistency.

Also, the description above lzma_filter_encoder_is_supported() about
not being able to list available filters was removed since
lzma_str_list_filters() will do this.
2023-02-24 21:09:39 +08:00
Lasse Collin 30e95bb44c liblzma: Avoid null pointer + 0 (undefined behavior in C).
In the C99 and C17 standards, section 6.5.6 paragraph 8 means that
adding 0 to a null pointer is undefined behavior. As of writing,
"clang -fsanitize=undefined" (Clang 15) diagnoses this. However,
I'm not aware of any compiler that would take advantage of this
when optimizing (Clang 15 included). It's good to avoid this anyway
since compilers might some day infer that pointer arithmetic implies
that the pointer is not NULL. That is, the following foo() would then
unconditionally return 0, even for foo(NULL, 0):

    void bar(char *a, char *b);

    int foo(char *a, size_t n)
    {
        bar(a, a + n);
        return a == NULL;
    }

In contrast to C, C++ explicitly allows null pointer + 0. So if
the above is compiled as C++ then there is no undefined behavior
in the foo(NULL, 0) call.

To me it seems that changing the C standard would be the sane
thing to do (just add one sentence) as it would ensure that a huge
amount of old code won't break in the future. Based on web searches
it seems that a large number of codebases (where null pointer + 0
occurs) are being fixed instead to be future-proof in case compilers
will some day optimize based on it (like making the above foo(NULL, 0)
return 0) which in the worst case will cause security bugs.

Some projects don't plan to change it. For example, gnulib and thus
many GNU tools currently require that null pointer + 0 is defined:

    https://lists.gnu.org/archive/html/bug-gnulib/2021-11/msg00000.html

    https://www.gnu.org/software/gnulib/manual/html_node/Other-portability-assumptions.html

In XZ Utils null pointer + 0 issue should be fixed after this
commit. This adds a few if-statements and thus branches to avoid
null pointer + 0. These check for size > 0 instead of ptr != NULL
because this way bugs where size > 0 && ptr == NULL will likely
get caught quickly. None of them are in hot spots so it shouldn't
matter for performance.

A little less readable version would be replacing

    ptr + offset

with

    offset != 0 ? ptr + offset : ptr

or creating a macro for it:

    #define my_ptr_add(ptr, offset) \
            ((offset) != 0 ? ((ptr) + (offset)) : (ptr))

Checking for offset != 0 instead of ptr != NULL allows GCC >= 8.1,
Clang >= 7, and Clang-based ICX to optimize it to the very same code
as ptr + offset. That is, it won't create a branch. So for hot code
this could be a good solution to avoid null pointer + 0. Unfortunately
other compilers like ICC 2021 or MSVC 19.33 (VS2022) will create a
branch from my_ptr_add().

Thanks to Marcin Kowalczyk for reporting the problem:
https://github.com/tukaani-project/xz/issues/36
2023-02-23 20:41:22 +02:00
Jia Tan fa9065fac5 liblzma: Adjust container.h for consistency with filter.h. 2023-02-23 20:27:59 +08:00
Jia Tan 00a721b63d liblzma: Fix small typos and reword a few things in filter.h. 2023-02-23 20:27:59 +08:00
Jia Tan 5b1c171d4f liblzma: Convert list of flags in lzma_mt to bulleted list. 2023-02-23 20:27:59 +08:00
Jia Tan dbd47622eb liblzma: Fix typo in documentation in container.h
lzma_microlzma_decoder -> lzma_microlzma_encoder
2023-02-23 20:27:59 +08:00
Jia Tan 14cd30806d liblzma: Improve documentation for container.h
Standardizing each function to always specify parameters and return
values. Also moved the parameters and return values to the end of each
function description.
2023-02-23 20:27:59 +08:00
Lasse Collin d831072cce liblzma: Very minor API doc tweaks.
Use "member" to refer to struct members as that's the term used
by the C standard.

Use lzma_options_delta.dist and such in docs so that in Doxygen's
HTML output they will link to the doc of the struct member.

Clean up a few trailing white spaces too.
2023-02-16 21:09:00 +02:00
Jia Tan f029daea39 liblzma: Adjust spacing in doc headers in bcj.h. 2023-02-17 00:54:33 +08:00
Jia Tan a5de68bac2 liblzma: Adjust documentation in bcj.h for consistent style. 2023-02-17 00:49:47 +08:00
Jia Tan efa498c13b liblzma: Rename field => member in documentation.
Also adjusted preset value => preset level.
2023-02-17 00:49:47 +08:00
Lasse Collin 718b22a6c5 liblzma: Silence a warning from MSVC.
It gives C4146 here since unary minus with unsigned integer
is still unsigned (which is the intention here). Doing it
with substraction makes it clearer and avoids the warning.

Thanks to Nathan Moinvaziri for reporting this.
2023-02-16 17:59:50 +02:00
Jia Tan 87c53553fa liblzma: Improve documentation for stream_flags.h
Standardizing each function to always specify parameters and return
values. Also moved the parameters and return values to the end of each
function description.

A few small things were reworded and long sentences broken up.
2023-02-16 21:04:54 +08:00
Jia Tan 13d99e75a5 liblzma: Improve documentation in lzma12.h.
All functions now explicitly specify parameter and return values.
2023-02-15 22:21:44 +08:00
Jia Tan 43ec344c86 liblzma: Improve documentation in check.h.
All functions now explicitly specify parameter and return values.
Also moved the note about SHA-256 functions not being exported to the
top of the file.
2023-02-15 00:59:16 +08:00
Jia Tan 9c71db4e88 liblzma: Improve documentation in index.h
All functions now explicitly specify parameter and return values.
2023-02-15 00:20:44 +08:00
Jia Tan 421f2f2e16 liblzma: Reword a comment in index.h. 2023-02-15 00:20:44 +08:00
Jia Tan b675394849 liblzma: Omit lzma_index_iter's internal field from Doxygen docs.
Add \private above this field and its sub-fields since it is not meant
to be modified by users.
2023-02-15 00:20:44 +08:00
Jia Tan 0c9e4fc2ad liblzma: Fix documentation for LZMA_MEMLIMIT_ERROR.
LZMA_MEMLIMIT_ERROR was missing the "<" character needed to put
documentation after a member.
2023-02-14 20:41:05 +08:00
Jia Tan 816fec125a liblzma: Improve documentation for base.h.
Standardizing each function to always specify params and return values.
Also fixed a small grammar mistake.
2023-02-14 20:41:05 +08:00
Jia Tan 862dacef1a liblzma: Add one more missing [out] annotation in vli.h 2023-02-14 00:12:34 +08:00
Jia Tan 867b08ae42 liblzma: Minor improvements to vli.h.
Added [out] annotations to parameters that are pointers and can have
their value changed. Also added a clarification to lzma_vli_is_valid.
2023-02-14 00:08:33 +08:00
Jia Tan 90d0e628ff liblzma: Add comments for macros in delta.h.
Document LZMA_DELTA_DIST_MIN and LZMA_DELTA_DIST_MAX for completeness
and to avoid Doxygen warnings.
2023-02-10 21:38:25 +08:00
Jia Tan 9255fffdb1 liblzma: Improve documentation in index_hash.h.
All functions now explicitly specify parameter and return values.
Also reworded the description of lzma_index_hash_init() for readability.
2023-02-10 21:35:23 +08:00
Jia Tan 912af91b10 liblzma: Improve documentation for version.h.
Specified parameter and return values for API functions and documented
a few more of the macros.
2023-02-04 20:11:36 +08:00
Jia Tan 2c78a83c6f liblzma: Fix bug in lzma_str_from_filters() not checking filters[] length.
The bug is only a problem in applications that do not properly terminate
the filters[] array with LZMA_VLI_UNKNOWN or have more than
LZMA_FILTERS_MAX filters. This bug does not affect xz.
2023-02-03 00:42:27 +08:00
Jia Tan 8dfc029e7a liblzma: Fix typos in comments in string_conversion.c. 2023-02-03 00:42:27 +08:00
Jia Tan 54ad83c1ae liblzma: Clarify block encoder and decoder documentation.
Added a few sentences to the description for lzma_block_encoder() and
lzma_block_decoder() to highlight that the Block Header must be coded
before calling these functions.
2023-02-03 00:22:53 +08:00
Jia Tan f680e771b3 Update lzma_block documentation for lzma_block_uncomp_encode(). 2023-02-03 00:22:53 +08:00
Jia Tan 504cf4af89 liblzma: Minor edits to lzma_block header_size documentation. 2023-02-03 00:22:53 +08:00
Jia Tan 115b720fb5 liblzma: Enumerate functions that read version in lzma_block. 2023-02-03 00:22:53 +08:00
Jia Tan 85ea0979ad liblzma: Clarify comment in block.h. 2023-02-03 00:22:53 +08:00
Jia Tan 1f7ab90d9c liblzma: Improve documentation for block.h.
Standardizing each function to always specify params and return values.
Output pointer parameters are also marked with doxygen style [out] to
make it clear. Any note sections were also moved above the parameter and
return sections for consistency.
2023-02-03 00:22:53 +08:00
Jia Tan c563a4bc55 liblzma: Clarify a comment about LZMA_STR_NO_VALIDATION.
The flag description for LZMA_STR_NO_VALIDATION was previously confusing
about the treatment for filters than cannot be used with .xz format
(lzma1) without using LZMA_STR_ALL_FILTERS. Now, it is clear that
LZMA_STR_NO_VALIDATION is not a super set of LZMA_STR_ALL_FILTERS.
2023-02-01 23:39:45 +08:00