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2024-02-14Add SPDX license identifier into 0BSD source code files.Lasse Collin1-0/+2
2024-02-14Change most public domain parts to 0BSD.Lasse Collin1-3/+0
Translations and doc/xz-file-format.txt and doc/lzma-file-format.txt were not touched. COPYING.0BSD was added.
2023-02-23liblzma: Avoid null pointer + 0 (undefined behavior in C).Lasse Collin1-2/+9
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
2023-01-02liblzma: Replaced hardcoded 0x0 index indicator byte with macroJia Tan1-1/+1
2016-11-21liblzma: Avoid multiple definitions of lzma_coder structures.Lasse Collin1-7/+9
Only one definition was visible in a translation unit. It avoided a few casts and temp variables but seems that this hack doesn't work with link-time optimizations in compilers as it's not C99/C11 compliant. Fixes: http://www.mail-archive.com/xz-devel@tukaani.org/msg00279.html
2012-07-17liblzma: Make the use of lzma_allocator const-correct.Lasse Collin1-3/+3
There is a tiny risk of causing breakage: If an application assigns lzma_stream.allocator to a non-const pointer, such code won't compile anymore. I don't know why anyone would do such a thing though, so in practice this shouldn't cause trouble. Thanks to Jan Kratochvil for the patch.
2011-05-17Add underscores to attributes (__attribute((__foo__))).Lasse Collin1-5/+6
2010-10-21liblzma: Update the comments in the API headers.Lasse Collin1-0/+1
Adding support for LZMA_FINISH for Index encoding and decoding needed tiny additions to the relevant .c files too.
2010-02-12Collection of language fixes to comments and docs.Lasse Collin1-1/+1
Thanks to Jonathan Nieder.
2009-12-31Revised the Index handling code.Lasse Collin1-21/+15
This breaks API and ABI but most apps are not affected since most apps don't use this part of the API. You will get a compile error if you are using anything that got broken. Summary of changes: - Ability to store Stream Flags, which are needed for random-access reading in multi-Stream files. - Separate function to set size of Stream Padding. - Iterator structure makes it possible to read the same lzma_index from multiple threads at the same time. - A lot faster code to locate Blocks. - Removed lzma_index_equal() without adding anything to replace it. I don't know what it should do exactly with the new features and what actually needs this function in the first place other than test_index.c, which now has its own code to compare lzma_indexes.
2009-04-28Fixed a crash in liblzma.Lasse Collin1-1/+1
liblzma tries to avoid useless free()/malloc() pairs in initialization when multiple files are handled using the same lzma_stream. This didn't work with filter chains due to comparison of wrong pointers in lzma_next_coder_init(), making liblzma think that no memory reallocation is needed even when it actually is. Easy way to trigger this bug is to decompress two files with a single xz command. The first file should have e.g. x86+LZMA2 as the filter chain, and the second file just LZMA2.
2009-04-13Put the interesting parts of XZ Utils into the public domain.Lasse Collin1-10/+3
Some minor documentation cleanups were made at the same time.
2009-02-02Modify LZMA_API macro so that it works on Windows withLasse Collin1-2/+2
other compilers than MinGW. This may hurt readability of the API headers slightly, but I don't know any better way to do this.
2009-01-20Add some single-call buffer-to-buffer coding functions.Lasse Collin1-6/+53
2008-11-19Oh well, big messy commit again. Some highlights:Lasse Collin1-7/+9
- Updated to the latest, probably final file format version. - Command line tool reworked to not use threads anymore. Threading will probably go into liblzma anyway. - Memory usage limit is now about 30 % for uncompression and about 90 % for compression. - Progress indicator with --verbose - Simplified --help and full --long-help - Upgraded to the last LGPLv2.1+ getopt_long from gnulib. - Some bug fixes
2008-08-28Sort of garbage collection commit. :-| Many things are stillLasse Collin1-11/+5
broken. API has changed a lot and it will still change a little more here and there. The command line tool doesn't have all the required changes to reflect the API changes, so it's easy to get "internal error" or trigger assertions.
2008-06-18Update the code to mostly match the new simpler file formatLasse Collin1-0/+222
specification. Simplify things by removing most of the support for known uncompressed size in most places. There are some miscellaneous changes here and there too. The API of liblzma has got many changes and still some more will be done soon. While most of the code has been updated, some things are not fixed (the command line tool will choke with invalid filter chain, if nothing else). Subblock filter is somewhat broken for now. It will be updated once the encoded format of the Subblock filter has been decided.