Commit Graph

1165 Commits

Author SHA1 Message Date
Lasse Collin 217958d887 xz, xzdec, lzmainfo: Use tuklib_attr_noreturn.
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".
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 90c94dddfd tuklib: Update tuklib_attr_noreturn for C11/C17 and C23.
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.
2023-09-22 20:06:21 +03:00
Lasse Collin 79334e7f20 MSVC: xz: Make file_io.c and file_io.h compatible with MSVC.
Thanks to Kelvin Lee for the original patches
and testing the modifications I made.
2023-09-22 20:00:38 +03:00
Lasse Collin c660b8d78b MSVC: xz: Use GetTickCount64() to implement mytime_now().
It's available since Windows Vista.
2023-09-22 20:00:38 +03:00
Kelvin Lee 5c6f892d41 MSVC: xz: Use _stricmp() instead of strcasecmp() in suffix.c. 2023-09-22 20:00:38 +03:00
Kelvin Lee e241051f50 MSVC: xz: Use _isatty() from <io.h> to implement isatty(). 2023-09-22 20:00:38 +03:00
Kelvin Lee d14bba8fc2 MSVC: xz: Use _fileno() instead of fileno(). 2023-09-22 20:00:38 +03:00
Kelvin Lee c4edd36767 MSVC: xzdec: Use _fileno and _setmode. 2023-09-22 20:00:37 +03:00
Kelvin Lee cfd1054b9b MSVC: Don't #include <unistd.h>. 2023-09-22 20:00:37 +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
Lasse Collin eccf128665 xz: Refactor thousand separator detection and disable it on MSVC.
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).
2023-08-31 19:50:05 +03:00
Lasse Collin f7093cd9d1 xz: Fix a too relaxed assertion and remove uses of SSIZE_MAX.
SSIZE_MAX isn't readily available on MSVC. Removing it means
that there is one thing less to worry when porting to MSVC.
2023-08-31 18:14:43 +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
Jamaika1 6bf33b704c
mythread.h: Fix typo error in Vista threads mythread_once().
The "once_" variable was accidentally referred to as just "once". This
prevented building with Vista threads when
HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR was not defined.
2023-08-08 20:07:59 +08:00
Lasse Collin 16068f6c30 xz: Omit an empty paragraph on the man page. 2023-08-02 17:15:12 +03:00
ChanTsune 81db3b8898 mythread.h: Disable signal functions in builds targeting Wasm + WASI.
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.)
2023-08-01 18:18:05 +03:00
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 b6b7d06585 xz: Translate the second "%s: " in message.c since French needs "%s : ".
This string is used to print a filename when using "xz -v" and
stderr isn't a terminal.
2023-07-18 17:37:33 +03:00
Lasse Collin be644042c3 xz: Make "%s: %s" translatable because French needs "%s : %s". 2023-07-18 17:34:18 +03:00
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 abc1d5601b xz: Update Authors list in a few files. 2023-07-18 00:51:48 +08:00
Jia Tan f99e2e4e53 xz: Fix typo in man page.
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.
2023-07-17 23:34:55 +08:00
Jia Tan f907705eb1 xz: Minor clean up for coder.c
* 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
2023-07-17 23:34:55 +08:00
Jia Tan 9adc9e5615 xz: Update man page Authors and date. 2023-07-17 23:34:55 +08:00
Jia Tan c12e429f26 xz: Add a section to man page for robot mode --filters-help. 2023-07-17 23:34:55 +08:00
Jia Tan e10f2db5d1 xz: Slight reword in xz man page for consistency.
Changed will print => prints in xz --robot --version description to
match --robot --info-memory description.
2023-07-17 23:34:55 +08:00
Jia Tan f5dc172a40 xz: Reorder robot mode subsections in the man page.
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
2023-07-17 23:34:55 +08:00
Jia Tan 9628be23ae xz: Update man page for new --filters-help option. 2023-07-17 23:34:55 +08:00
Jia Tan a165d7df19 xz: Add a new --filters-help option.
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.
2023-07-17 23:34:55 +08:00
Jia Tan 95f1a414b1 xz: Update the man page for --block-list and --filtersX
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.
2023-07-17 23:34:55 +08:00
Jia Tan 47a63cad2a xz: Update --long-help for the new --filtersX option. 2023-07-17 23:34:55 +08:00
Jia Tan 8b9913a13d xz: Ignore filter chains that are set but never used in --block-list.
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.
2023-07-17 23:34:55 +08:00
Jia Tan 183819bfd9 xz: Set the Block size for mt encoding correctly.
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.
2023-07-17 23:34:55 +08:00
Jia Tan afb2dbec3d xz: Validate --flush-timeout for all specified filter chains. 2023-07-17 23:34:55 +08:00
Jia Tan 5f0c5a0438 xz: Allows --block-list filters to scale down memory usage.
Previously, only the default filter chain could have its memory usage
adjusted. The filter chains specified with --filtersX were not checked
for memory usage. Now, all used filter chains will be adjusted if
necessary.
2023-07-17 23:34:55 +08:00
Jia Tan 479fd58d60 xz: Do not include block splitting if encoders are disabled.
The block splitting logic and split_block() function are not needed if
encoders are disabled. This will help slightly reduce the binary size
when built without encoders and allow split_block() to use functions
that require encoders being enabled.
2023-07-17 23:34:55 +08:00
Jia Tan f86ede2250 xz: Free filters[] in debug mode.
This will only free filter chains created with --filters1-9 since the
default filter chain may be set from a static function variable. The
complexity to free the default filter chain is not worth the burden on
code maintenance.
2023-07-17 23:34:55 +08:00
Jia Tan f281cd0d69 xz: Add a message if --block-list is used outside of xz compresssion.
--block-list is only supported with compression in xz format. This avoids
silently ignoring when --block-list is unused.
2023-07-17 23:34:55 +08:00
Jia Tan d6af7f3470 xz: Create command line options for filters[1-9].
The new command line options are meant to be combined with --block-list.
They work as an optional extension to --block-list to specify a custom
filter chain for each block listed. The new options allow the creation
of up to 9 reusable filter chains. For instance:

xz --block-list=1:10MiB,3:5MiB,,2:5MiB,1:0 --filters1=delta--lzma2 \
--filters2=x86--lzma2 --filters3=arm64--lzma2

Will create the following blocks:
1. A block of size 10 MiB with filter chain delta, lzma2.
2. A block of size 5 MiB with filter chain arm64, lzma2.
3. A block of size 5 MiB with filter chain arm64, lzma2.
4. A block of size 5 MiB with filter chain x86, lzma2.
5. A block containing the rest of the file contents with filter chain
   delta, lzma2.
2023-07-17 23:34:55 +08:00
Jia Tan 072d292501 xz: Use lzma_filters_free() in forget_filter_chain().
This is a little cleaner than the previous implementation of
forget_filter_chain(). It is also more consistent since
lzma_str_to_filters() will always terminate the filter chain so there
is no need to terminate it later in coder_set_compression_settings().
2023-07-17 23:34:55 +08:00
Jia Tan 3d21da5cff xz: Separate string to filter conversion into a helper function.
Converting from string to filter will also need to be done for block
specific filter chains.
2023-07-17 23:34:55 +08:00
Jia Tan 5f3b898d07 xz: Update --long-help and man page for new --filters option. 2023-07-17 23:34:55 +08:00
Jia Tan 9ded880a02 xz: Add --filters option to CLI.
The --filters option uses the new lzma_str_to_filters() function
to convert a string into a full filter chain. Using this option
will reset all previous filters set by --preset, --[filter], or
--filters.
2023-07-17 23:34:55 +08:00
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 9ad64bdf30 tuklib_integer.h: Reverts previous commit.
Previous commit 6be460dde0 would cause an
error if the integer size was 32 bit.
2023-05-04 20:30:25 +08:00
Jia Tan 6be460dde0 tuklib_integer.h: Changes two other UINT_MAX == UINT32_MAX to >=. 2023-05-04 19:25:20 +08:00
Lasse Collin 44c0c5eae9 tuklib_integer.h: Fix a recent copypaste error in Clang detection.
Wrong line was changed in 7062348bf3.
Also, this has >= instead of == since ints larger than 32 bits would
work too even if not relevant in practice.
2023-05-03 22:55:16 +03:00
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
Jia Tan 7062348bf3 tuklib_integer: Use __builtin_clz() with Clang.
Clang has support for __builtin_clz(), but previously Clang would
fallback to either the MSVC intrinsic or the regular C code. This was
discovered due to a bug where a new version of Clang required the
<intrin.h> header file in order to use the MSVC intrinsics.

Thanks to Anton Kochkov for notifying us about the bug.
2023-04-19 21:59:03 +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
Lasse Collin 717aa3651c xz: Simplify the error-label in Capsicum sandbox code.
Also remove unneeded "sandbox_allowed = false;" as this code
will never be run more than once (making it work with multiple
input files isn't trivial).
2023-03-11 18:46:45 +02:00
Lasse Collin a0eecc235d xz: Make Capsicum sandbox more strict with stdin and stdout. 2023-03-08 23:22:15 +08:00
Jia Tan 916448d624 Revert: "Add warning if Capsicum sandbox system calls are unsupported."
The warning causes the exit status to be 2, so this will cause problems
for many scripted use cases for xz. The sandbox usage is already very
limited already, so silently disabling this allows it to be more usable.
2023-03-08 23:22:11 +08:00
Jia Tan 01587dda2a xz: Fix -Wunused-label in io_sandbox_enter().
Thanks to Xin Li for recommending the fix.
2023-03-07 20:02:22 +08:00
Jia Tan 5fb9367866 xz: Add warning if Capsicum sandbox system calls are unsupported.
The warning is only used when errno == ENOSYS. Otherwise, xz still
issues a fatal error.
2023-03-06 21:37:45 +08:00
Jia Tan 61ee82cb12 xz: Skip Capsicum sandbox system calls when they are unsupported.
If a system has the Capsicum header files but does not actually
implement the system calls, then this would render xz unusable. Instead,
we can check if errno == ENOSYS and not issue a fatal error.
2023-03-06 21:27:53 +08:00
Jia Tan f070722b57 xz: Reorder cap_enter() to beginning of capsicum sandbox code.
cap_enter() puts the process into the sandbox. If later calls to
cap_rights_limit() fail, then the process can still have some extra
protections.
2023-03-06 21:08:26 +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