
XZ Utils Release Notes
======================

5.3.4alpha (2022-11-15)

    * All fixes from 5.2.7 and 5.2.8.

    * liblzma:

        - Minor improvements to the threaded decoder.

        - Added CRC64 implementation that uses SSSE3, SSE4.1, and CLMUL
          instructions on 32/64-bit x86 and E2K. On 32-bit x86 it's
          not enabled unless --disable-assembler is used but then
          the non-CLMUL code might be slower. Processor support is
          detected at runtime so this is built by default on x86-64
          and E2K. On these platforms, if compiler flags indicate
          unconditional CLMUL support (-msse4.1 -mpclmul) then the
          generic version is not built, making liblzma 8-9 KiB smaller
          compared to having both versions included.

          With extremely compressible files this can make decompression
          up to twice as fast but with typical files 5 % improvement
          is a more realistic expectation.

          The CLMUL version is slower than the generic version with
          tiny inputs (especially at 1-8 bytes per call, but up to
          16 bytes). In normal use in xz this doesn't matter at all.

        - Added an experimental ARM64 filter. This is *not* the final
          version! Files created with this experimental version won't
          be supported in the future versions! The filter design is
          a compromise where improving one use case makes some other
          cases worse.

        - Added decompression support for the .lz (lzip) file format
          version 0 and the original unextended version 1. See the
          API docs of lzma_lzip_decoder() for details. Also
          lzma_auto_decoder() supports .lz files.

        - Building with --disable-threads --enable-small
          is now thread-safe if the compiler supports
          __attribute__((__constructor__))

    * xz:

        - Added support for OpenBSD's pledge(2) as a sandboxing method.

        - Don't mention endianness for ARM and ARM-Thumb filters in
          --long-help. The filters only work for little endian
          instruction encoding but modern ARM processors using
          big endian data access still use little endian
          instruction encoding. So the help text was misleading.
          In contrast, the PowerPC filter is only for big endian
          32/64-bit PowerPC code. Little endian PowerPC would need
          a separate filter.

        - Added --experimental-arm64. This will be renamed once the
          filter is finished. Files created with this experimental
          filter will not be supported in the future!

        - Added new fields to the output of xz --robot --info-memory.

        - Added decompression support for the .lz (lzip) file format
          version 0 and the original unextended version 1. It is
          autodetected by default. See also the option --format on
          the xz man page.

    * Scripts now support the .lz format using xz.

    * Build systems:

        - New #defines in config.h: HAVE_ENCODER_ARM64,
          HAVE_DECODER_ARM64, HAVE_LZIP_DECODER, HAVE_CPUID_H,
          HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR, HAVE_USABLE_CLMUL

        - New configure options: --disable-clmul-crc,
          --disable-microlzma, --disable-lzip-decoder, and
          'pledge' is now an option in --enable-sandbox (but
          it's autodetected by default anyway).

        - INSTALL was updated to document the new configure options.

        - PACKAGERS now lists also --disable-microlzma and
          --disable-lzip-decoder as configure options that must
          not be used in builds for non-embedded use.

    * Tests:

        - Fix some of the tests so that they skip instead of fail if
          certain features have been disabled with configure options.
          It's still not perfect.

        - Other improvements to tests.

    * Updated translations: Croatian, Finnish, Hungarian, Polish,
      Romanian, Spanish, Swedish, and Ukrainian.


5.3.3alpha (2022-08-22)

    * All fixes from 5.2.6.

    * liblzma:

        - Fixed 32-bit build.

        - Added threaded .xz decompressor lzma_stream_decoder_mt().
          It can use multiple threads with .xz files that have multiple
          Blocks with size information in Block Headers. The threaded
          encoder in xz has always created such files.

          Single-threaded encoder cannot store the size information in
          Block Headers even if one used LZMA_FULL_FLUSH to create
          multiple Blocks, so this threaded decoder cannot use multiple
          threads with such files.

          If there are multiple Streams (concatenated .xz files), one
          Stream will be decompressed completely before starting the
          next Stream.

        - A new decoder flag LZMA_FAIL_FAST was added. It makes the
          threaded decompressor report errors soon instead of first
          flushing all pending data before the error location.

    * xz:

        - Using -T0 (--threads=0) will now use multi-threaded encoder
          even on a single-core system. This is to ensure that output
          from the same xz binary is identical on both single-core and
          multi-core systems.

        - A default soft memory usage limit is now used for compression
          when -T0 is used and no explicit limit has been specified.
          This soft limit is used to restrict the number of threads
          but if the limit is exceeded with even one thread then xz
          will continue with one thread using the multi-threaded
          encoder and this limit is ignored. If the number of threads
          is specified manually then no default limit will be used;
          this affects only -T0.

          This change helps on systems that have very many cores and
          using all of them for xz makes no sense. Previously xz -T0
          could run out of memory on such systems because it attempted
          to reserve memory for too many threads.

          This also helps with 32-bit builds which don't have a large
          amount of address space that would be required for many
          threads. The default limit is 1400 MiB on all 32-bit
          platforms with -T0.

          Now xz -T0 should just work. It might use too few threads
          in some cases but at least it shouldn't easily run out of
          memory. It's possible that this will be tweaked before 5.4.0.

        - Changes to --memlimit-compress and --no-adjust:

          In single-threaded mode, --memlimit-compress can make xz
          scale down the LZMA2 dictionary size to meet the memory usage
          limit. This obviously affects the compressed output. However,
          if xz was in threaded mode, --memlimit-compress could make xz
          reduce the number of threads but it wouldn't make xz switch
          from multi-threaded mode to single-threaded mode or scale
          down the LZMA2 dictionary size. This seemed illogical.

          Now --memlimit-compress can make xz switch to single-threaded
          mode if one thread in multi-threaded mode uses too much
          memory. If memory usage is still too high, then the LZMA2
          dictionary size can be scaled down too.

          The option --no-adjust was also changed so that it no longer
          prevents xz from scaling down the number of threads as that
          doesn't affect compressed output (only performance). After
          this commit --no-adjust only prevents adjustments that affect
          compressed output, that is, with --no-adjust xz won't switch
          from multithreaded mode to single-threaded mode and won't
          scale down the LZMA2 dictionary size.

        - Added a new option --memlimit-decompress-mt=LIMIT. This is
          used to limit the number of decompressor threads (possibly
          falling back to single-threaded mode) but it will never make
          xz refuse to decompress a file. This has a system-specific
          default value because without any limit xz could end up
          allocating memory for the whole compressed input file, the
          whole uncompressed output file, multiple thread-specific
          decompressor instances and so on. Basically xz could
          attempt to use an insane amount of memory even with fairly
          common files.

          The new option works together with the existing option
          --memlimit-decompress=LIMIT. The old option sets a hard limit
          that must not be exceeded (xz will refuse to decompress)
          while the new option only restricts the number of threads.
          If the limit set with --memlimit-mt-decompress is greater
          than the limit set with --memlimit-compress, then the latter
          value is used also for --memlimit-mt-decompress.

    * Tests:

        - Added a few more tests.

        - Added tests/code_coverage.sh to create a code coverage report
          of the tests.

    * Build systems:

        - Automake's parallel test harness is now used to make tests
          finish faster.

        - Added the CMake files to the distribution tarball. These were
          supposed to be in 5.2.5 already.

        - Added liblzma tests to the CMake build.

        - Windows: Fix building of liblzma.dll with the included
          Visual Studio project files.


5.3.2alpha (2021-10-28)

    This release was made on short notice so that recent erofs-utils can
    be built with LZMA support without needing a snapshot from xz.git.
    Thus many pending things were not included, not even updated
    translations (which would need to be updated for the new --list
    strings anyway).

    * All fixes from 5.2.5.

    * xz:

        - When copying metadata from the source file to the destination
          file, don't try to set the group (GID) if it is already set
          correctly. This avoids a failure on OpenBSD (and possibly on
          a few other OSes) where files may get created so that their
          group doesn't belong to the user, and fchown(2) can fail even
          if it needs to do nothing.

        - The --keep option now accepts symlinks, hardlinks, and
          setuid, setgid, and sticky files. Previously this required
          using --force.

        - Split the long strings used in --list and --info-memory modes
          to make them much easier for translators.

        - If built with sandbox support and enabling the sandbox fails,
          xz will now immediately exit with exit status of 1. Previously
          it would only display a warning if -vv was used.

        - Cap --memlimit-compress to 2000 MiB on MIPS32 because on
          MIPS32 userspace processes are limited to 2 GiB of address
          space.

    * liblzma:

        - Added lzma_microlzma_encoder() and lzma_microlzma_decoder().
          The API is in lzma/container.h.

          The MicroLZMA format is a raw LZMA stream (without end marker)
          whose first byte (always 0x00) has been replaced with
          bitwise-negation of the LZMA properties (lc/lp/pb). It was
          created for use in EROFS but may be used in other contexts
          as well where it is important to avoid wasting bytes for
          stream headers or footers. The format is also supported by
          XZ Embedded.

          The MicroLZMA encoder API in liblzma can compress into a
          fixed-sized output buffer so that as much data is compressed
          as can be fit into the buffer while still creating a valid
          MicroLZMA stream. This is needed for EROFS.

        - Added fuzzing support.

        - Support Intel Control-flow Enforcement Technology (CET) in
          32-bit x86 assembly files.

        - Visual Studio: Use non-standard _MSVC_LANG to detect C++
          standard version in the lzma.h API header. It's used to
          detect when "noexcept" can be used.

    * Scripts:

        - Fix exit status of xzdiff/xzcmp. Exit status could be 2 when
          the correct value is 1.

        - Fix exit status of xzgrep.

        - Detect corrupt .bz2 files in xzgrep.

        - Add zstd support to xzgrep and xzdiff/xzcmp.

        - Fix less(1) version detection in xzless. It failed if the
          version number from "less -V" contained a dot.

    * Fix typos and technical issues in man pages.

    * Build systems:

        - Windows: Fix building of resource files when config.h isn't
          used. CMake + Visual Studio can now build liblzma.dll.

        - Various fixes to the CMake support. It might still need a few
          more fixes even for liblzma-only builds.


5.3.1alpha (2018-04-29)

    * All fixes from 5.2.4.

    * Add lzma_file_info_decoder() into liblzma and use it in xz to
      implement the --list feature.

    * Capsicum sandbox support is enabled by default where available
      (FreeBSD >= 10).


5.2.8 (2022-11-13)

    * xz:

        - If xz cannot remove an input file when it should, this
          is now treated as a warning (exit status 2) instead of
          an error (exit status 1). This matches GNU gzip and it
          is more logical as at that point the output file has
          already been successfully closed.

        - Fix handling of .xz files with an unsupported check type.
          Previously such printed a warning message but then xz
          behaved as if an error had occurred (didn't decompress,
          exit status 1). Now a warning is printed, decompression
          is done anyway, and exit status is 2. This used to work
          slightly before 5.0.0. In practice this bug matters only
          if xz has been built with some check types disabled. As
          instructed in PACKAGERS, such builds should be done in
          special situations only.

        - Fix "xz -dc --single-stream tests/files/good-0-empty.xz"
          which failed with "Internal error (bug)". That is,
          --single-stream was broken if the first .xz stream in
          the input file didn't contain any uncompressed data.

        - Fix displaying file sizes in the progress indicator when
          working in passthru mode and there are multiple input files.
          Just like "gzip -cdf", "xz -cdf" works like "cat" when the
          input file isn't a supported compressed file format. In
          this case the file size counters weren't reset between
          files so with multiple input files the progress indicator
          displayed an incorrect (too large) value.

    * liblzma:

        - API docs in lzma/container.h:
            * Update the list of decoder flags in the decoder
              function docs.
            * Explain LZMA_CONCATENATED behavior with .lzma files
              in lzma_auto_decoder() docs.

        - OpenBSD: Use HW_NCPUONLINE to detect the number of
          available hardware threads in lzma_physmem().

        - Fix use of wrong macro to detect x86 SSE2 support.
          __SSE2_MATH__ was used with GCC/Clang but the correct
          one is __SSE2__. The first one means that SSE2 is used
          for floating point math which is irrelevant here.
          The affected SSE2 code isn't used on x86-64 so this affects
          only 32-bit x86 builds that use -msse2 without -mfpmath=sse
          (there is no runtime detection for SSE2). It improves LZMA
          compression speed (not decompression).

        - Fix the build with Intel C compiler 2021 (ICC, not ICX)
          on Linux. It defines __GNUC__ to 10 but doesn't support
          the __symver__ attribute introduced in GCC 10.

    * Scripts: Ignore warnings from xz by using --quiet --no-warn.
      This is needed if the input .xz files use an unsupported
      check type.

    * Translations:

        - Updated Croatian and Turkish translations.

        - One new translations wasn't included because it needed
          technical fixes. It will be in upcoming 5.4.0. No new
          translations will be added to the 5.2.x branch anymore.

        - Renamed the French man page translation file from
          fr_FR.po to fr.po and thus also its install directory
          (like /usr/share/man/fr_FR -> .../fr).

        - Man page translations for upcoming 5.4.0 are now handled
          in the Translation Project.

    * Update doc/faq.txt a little so it's less out-of-date.


5.2.7 (2022-09-30)

    * liblzma:

        - Made lzma_filters_copy() to never modify the destination
          array if an error occurs. lzma_stream_encoder() and
          lzma_stream_encoder_mt() already assumed this. Before this
          change, if a tiny memory allocation in lzma_filters_copy()
          failed it would lead to a crash (invalid free() or invalid
          memory reads) in the cleanup paths of these two encoder
          initialization functions.

        - Added missing integer overflow check to lzma_index_append().
          This affects xz --list and other applications that decode
          the Index field from .xz files using lzma_index_decoder().
          Normal decompression of .xz files doesn't call this code
          and thus most applications using liblzma aren't affected
          by this bug.

        - Single-threaded .xz decoder (lzma_stream_decoder()): If
          lzma_code() returns LZMA_MEMLIMIT_ERROR it is now possible
          to use lzma_memlimit_set() to increase the limit and continue
          decoding. This was supposed to work from the beginning
          but there was a bug. With other decoders (.lzma or
          threaded .xz decoder) this already worked correctly.

        - Fixed accumulation of integrity check type statistics in
          lzma_index_cat(). This bug made lzma_index_checks() return
          only the type of the integrity check of the last Stream
          when multiple lzma_indexes were concatenated. Most
          applications don't use these APIs but in xz it made
          xz --list not list all check types from concatenated .xz
          files. In xz --list --verbose only the per-file "Check:"
          lines were affected and in xz --robot --list only the "file"
          line was affected.

        - Added ABI compatibility with executables that were linked
          against liblzma in RHEL/CentOS 7 or other liblzma builds
          that had copied the problematic patch from RHEL/CentOS 7
          (xz-5.2.2-compat-libs.patch). For the details, see the
          comment at the top of src/liblzma/validate_map.sh.

          WARNING: This uses __symver__ attribute with GCC >= 10.
          In other cases the traditional __asm__(".symver ...")
          is used. Using link-time optimization (LTO, -flto) with
          GCC versions older than 10 can silently result in
          broken liblzma.so.5 (incorrect symbol versions)! If you
          want to use -flto with GCC, you must use GCC >= 10.
          LTO with Clang seems to work even with the traditional
          __asm__(".symver ...") method.

    * xzgrep: Fixed compatibility with old shells that break if
      comments inside command substitutions have apostrophes (').
      This problem was introduced in 5.2.6.

    * Build systems:

        - New #define in config.h: HAVE_SYMBOL_VERSIONS_LINUX

        - Windows: Fixed liblzma.dll build with Visual Studio project
          files. It broke in 5.2.6 due to a change that was made to
          improve CMake support.

        - Windows: Building liblzma with UNICODE defined should now
          work.

        - CMake files are now actually included in the release tarball.
          They should have been in 5.2.5 already.

        - Minor CMake fixes and improvements.

    * Added a new translation: Turkish


5.2.6 (2022-08-12)

    * xz:

        - The --keep option now accepts symlinks, hardlinks, and
          setuid, setgid, and sticky files. Previously this required
          using --force.

        - When copying metadata from the source file to the destination
          file, don't try to set the group (GID) if it is already set
          correctly. This avoids a failure on OpenBSD (and possibly on
          a few other OSes) where files may get created so that their
          group doesn't belong to the user, and fchown(2) can fail even
          if it needs to do nothing.

        - Cap --memlimit-compress to 2000 MiB instead of 4020 MiB on
          MIPS32 because on MIPS32 userspace processes are limited
          to 2 GiB of address space.

    * liblzma:

        - Fixed a missing error-check in the threaded encoder. If a
          small memory allocation fails, a .xz file with an invalid
          Index field would be created. Decompressing such a file would
          produce the correct output but result in an error at the end.
          Thus this is a "mild" data corruption bug. Note that while
          a failed memory allocation can trigger the bug, it cannot
          cause invalid memory access.

        - The decoder for .lzma files now supports files that have
          uncompressed size stored in the header and still use the
          end of payload marker (end of stream marker) at the end
          of the LZMA stream. Such files are rare but, according to
          the documentation in LZMA SDK, they are valid.
          doc/lzma-file-format.txt was updated too.

        - Improved 32-bit x86 assembly files:
            * Support Intel Control-flow Enforcement Technology (CET)
            * Use non-executable stack on FreeBSD.

        - Visual Studio: Use non-standard _MSVC_LANG to detect C++
          standard version in the lzma.h API header. It's used to
          detect when "noexcept" can be used.

    * xzgrep:

        - Fixed arbitrary command injection via a malicious filename
          (CVE-2022-1271, ZDI-CAN-16587). A standalone patch for
          this was released to the public on 2022-04-07. A slight
          robustness improvement has been made since then and, if
          using GNU or *BSD grep, a new faster method is now used
          that doesn't use the old sed-based construct at all. This
          also fixes bad output with GNU grep >= 3.5 (2020-09-27)
          when xzgrepping binary files.

          This vulnerability was discovered by:
          cleemy desu wayo working with Trend Micro Zero Day Initiative

        - Fixed detection of corrupt .bz2 files.

        - Improved error handling to fix exit status in some situations
          and to fix handling of signals: in some situations a signal
          didn't make xzgrep exit when it clearly should have. It's
          possible that the signal handling still isn't quite perfect
          but hopefully it's good enough.

        - Documented exit statuses on the man page.

        - xzegrep and xzfgrep now use "grep -E" and "grep -F" instead
          of the deprecated egrep and fgrep commands.

        - Fixed parsing of the options -E, -F, -G, -P, and -X. The
          problem occurred when multiple options were specied in
          a single argument, for example,

              echo foo | xzgrep -Fe foo

          treated foo as a filename because -Fe wasn't correctly
          split into -F -e.

        - Added zstd support.

    * xzdiff/xzcmp:

        - Fixed wrong exit status. Exit status could be 2 when the
          correct value is 1.

        - Documented on the man page that exit status of 2 is used
          for decompression errors.

        - Added zstd support.

    * xzless:

        - Fix less(1) version detection. It failed if the version number
          from "less -V" contained a dot.

    * Translations:

        - Added new translations: Catalan, Croatian, Esperanto,
          Korean, Portuguese, Romanian, Serbian, Spanish, Swedish,
          and Ukrainian

        - Updated the Brazilian Portuguese translation.

        - Added French man page translation. This and the existing
          German translation aren't complete anymore because the
          English man pages got a few updates and the translators
          weren't reached so that they could update their work.

    * Build systems:

        - Windows: Fix building of resource files when config.h isn't
          used. CMake + Visual Studio can now build liblzma.dll.

        - Various fixes to the CMake support. Building static or shared
          liblzma should work fine in most cases. In contrast, building
          the command line tools with CMake is still clearly incomplete
          and experimental and should be used for testing only.


5.2.5 (2020-03-17)

    * liblzma:

        - Fixed several C99/C11 conformance bugs. Now the code is clean
          under gcc/clang -fsanitize=undefined. Some of these changes
          might have a negative effect on performance with old GCC
          versions or compilers other than GCC and Clang. The configure
          option --enable-unsafe-type-punning can be used to (mostly)
          restore the old behavior but it shouldn't normally be used.

        - Improved API documentation of lzma_properties_decode().

        - Added a very minor encoder speed optimization.

    * xz:

        - Fixed a crash in "xz -dcfv not_an_xz_file". All four options
          were required to trigger it. The crash occurred in the
          progress indicator code when xz was in passthru mode where
          xz works like "cat".

        - Fixed an integer overflow with 32-bit off_t. It could happen
          when decompressing a file that has a long run of zero bytes
          which xz would try to write as a sparse file. Since the build
          system enables large file support by default, off_t is
          normally 64-bit even on 32-bit systems.

        - Fixes for --flush-timeout:
            * Fix semi-busy-waiting.
            * Avoid unneeded flushes when no new input has arrived
              since the previous flush was completed.

        - Added a special case for 32-bit xz: If --memlimit-compress is
          used to specify a limit that exceeds 4020 MiB, the limit will
          be set to 4020 MiB. The values "0" and "max" aren't affected
          by this and neither is decompression. This hack can be
          helpful when a 32-bit xz has access to 4 GiB address space
          but the specified memlimit exceeds 4 GiB. This can happen
          e.g. with some scripts.

        - Capsicum sandbox is now enabled by default where available
          (FreeBSD >= 10). The sandbox debug messages (xz -vv) were
          removed since they seemed to be more annoying than useful.

        - DOS build now requires DJGPP 2.05 instead of 2.04beta.
          A workaround for a locale problem with DJGPP 2.05 was added.

    * xzgrep and other scripts:

        - Added a configure option --enable-path-for-scripts=PREFIX.
          It is disabled by default except on Solaris where the default
          is /usr/xpg4/bin. See INSTALL for details.

        - Added a workaround for a POSIX shell detection problem on
          Solaris.

    * Build systems:

        - Added preliminary build instructions for z/OS. See INSTALL
          section 1.2.9.

        - Experimental CMake support was added. It should work to build
          static liblzma on a few operating systems. It may or may not
          work to build shared liblzma. On some platforms it can build
          xz and xzdec too but those are only for testing. See the
          comment in the beginning of CMakeLists.txt for details.

        - Visual Studio project files were updated.
          WindowsTargetPlatformVersion was removed from VS2017 files
          and set to "10.0" in the added VS2019 files. In the future
          the VS project files will be removed when CMake support is
          good enough.

        - New #defines in config.h: HAVE___BUILTIN_ASSUME_ALIGNED,
          HAVE___BUILTIN_BSWAPXX, and TUKLIB_USE_UNSAFE_TYPE_PUNNING.

        - autogen.sh has a new optional dependency on po4a and a new
          option --no-po4a to skip that step. This matters only if one
          wants to remake the build files. po4a is used to update the
          translated man pages but as long as the man pages haven't
          been modified, there's nothing to update and one can use
          --no-po4a to avoid the dependency on po4a.

    * Translations:

        - XZ Utils translations are now handled by the Translation
          Project: https://translationproject.org/domain/xz.html

        - All man pages are now included in German too.

        - New xz translations: Brazilian Portuguese, Finnish,
          Hungarian, Chinese (simplified), Chinese (traditional),
          and Danish (partial translation)

        - Updated xz translations: French, German, Italian, and Polish

        - Unfortunately a few new xz translations weren't included due
          to technical problems like too long lines in --help output or
          misaligned column headings in tables. In the future, many of
          these strings will be split and e.g. the table column
          alignment will be handled in software. This should make the
          strings easier to translate.


5.2.4 (2018-04-29)

    * liblzma:

        - Allow 0 as memory usage limit instead of returning
          LZMA_PROG_ERROR. Now 0 is treated as if 1 byte was specified,
          which effectively is the same as 0.

        - Use "noexcept" keyword instead of "throw()" in the public
          headers when a C++11 (or newer standard) compiler is used.

        - Added a portability fix for recent Intel C Compilers.

        - Microsoft Visual Studio build files have been moved under
          windows/vs2013 and windows/vs2017.

    * xz:

        - Fix "xz --list --robot missing_or_bad_file.xz" which would
          try to print an uninitialized string and thus produce garbage
          output. Since the exit status is non-zero, most uses of such
          a command won't try to interpret the garbage output.

        - "xz --list foo.xz" could print "Internal error (bug)" in a
          corner case where a specific memory usage limit had been set.


5.2.3 (2016-12-30)

    * xz:

        - Always close a file before trying to delete it to avoid
          problems on some operating system and file system combinations.

        - Fixed copying of file timestamps on Windows.

        - Added experimental (disabled by default) sandbox support using
          Capsicum (FreeBSD >= 10). See --enable-sandbox in INSTALL.

    * C99/C11 conformance fixes to liblzma. The issues affected at least
      some builds using link-time optimizations.

    * Fixed bugs in the rarely-used function lzma_index_dup().

    * Use of external SHA-256 code is now disabled by default.
      It can still be enabled by passing --enable-external-sha256
      to configure. The reasons to disable it by default (see INSTALL
      for more details):

        - Some OS-specific SHA-256 implementations conflict with
          OpenSSL and cause problems in programs that link against both
          liblzma and libcrypto. At least FreeBSD 10 and MINIX 3.3.0
          are affected.

        - The internal SHA-256 is faster than the SHA-256 code in
          some operating systems.

    * Changed CPU core count detection to use sched_getaffinity() on
      GNU/Linux and GNU/kFreeBSD.

    * Fixes to the build-system and xz to make xz buildable even when
      encoders, decoders, or threading have been disabled from libilzma
      using configure options. These fixes added two new #defines to
      config.h: HAVE_ENCODERS and HAVE_DECODERS.


5.2.2 (2015-09-29)

    * Fixed bugs in QNX-specific code.

    * Omitted the use of pipe2() even if it is available to avoid
      portability issues with some old Linux and glibc combinations.

    * Updated German translation.

    * Added project files to build static and shared liblzma (not the
      whole XZ Utils) with Visual Studio 2013 update 2 or later.

    * Documented that threaded decompression hasn't been implemented
      yet. A 5.2.0 NEWS entry describing multi-threading support had
      incorrectly said "decompression" when it should have said
      "compression".


5.2.1 (2015-02-26)

    * Fixed a compression-ratio regression in fast mode of LZMA1 and
      LZMA2. The bug is present in 5.1.4beta and 5.2.0 releases.

    * Fixed a portability problem in xz that affected at least OpenBSD.

    * Fixed xzdiff to be compatible with FreeBSD's mktemp which differs
      from most other mktemp implementations.

    * Changed CPU core count detection to use cpuset_getaffinity() on
      FreeBSD.


5.2.0 (2014-12-21)

    Since 5.1.4beta:

    * All fixes from 5.0.8

    * liblzma: Fixed lzma_stream_encoder_mt_memusage() when a preset
      was used.

    * xzdiff: If mktemp isn't installed, mkdir will be used as
      a fallback to create a temporary directory. Installing mktemp
      is still recommended.

    * Updated French, German, Italian, Polish, and Vietnamese
      translations.

    Summary of fixes and new features added in the 5.1.x development
    releases:

    * liblzma:

        - Added support for multi-threaded compression. See the
          lzma_mt structure, lzma_stream_encoder_mt(), and
          lzma_stream_encoder_mt_memusage() in <lzma/container.h>,
          lzma_get_progress() in <lzma/base.h>, and lzma_cputhreads()
          in <lzma/hardware.h> for details.

        - Made the uses of lzma_allocator const correct.

        - Added lzma_block_uncomp_encode() to create uncompressed
          .xz Blocks using LZMA2 uncompressed chunks.

        - Added support for LZMA_IGNORE_CHECK.

        - A few speed optimizations were made.

        - Added support for symbol versioning. It is enabled by default
          on GNU/Linux, other GNU-based systems, and FreeBSD.

        - liblzma (not the whole XZ Utils) should now be buildable
          with MSVC 2013 update 2 or later using windows/config.h.

    * xz:

        - Fixed a race condition in the signal handling. It was
          possible that e.g. the first SIGINT didn't make xz exit
          if reading or writing blocked and one had bad luck. The fix
          is non-trivial, so as of writing it is unknown if it will be
          backported to the v5.0 branch.

        - Multi-threaded compression can be enabled with the
          --threads (-T) option.
          [Fixed: This originally said "decompression".]

        - New command line options in xz: --single-stream,
          --block-size=SIZE, --block-list=SIZES,
          --flush-timeout=TIMEOUT, and --ignore-check.

        - xz -lvv now shows the minimum xz version that is required to
          decompress the file. Currently it is 5.0.0 for all supported
          .xz files except files with empty LZMA2 streams require 5.0.2.

    * xzdiff and xzgrep now support .lzo files if lzop is installed.
      The .tzo suffix is also recognized as a shorthand for .tar.lzo.


5.1.4beta (2014-09-14)

    * All fixes from 5.0.6

    * liblzma: Fixed the use of presets in threaded encoder
      initialization.

    * xz --block-list and --block-size can now be used together
      in single-threaded mode. Previously the combination only
      worked in multi-threaded mode.

    * Added support for LZMA_IGNORE_CHECK to liblzma and made it
      available in xz as --ignore-check.

    * liblzma speed optimizations:

        - Initialization of a new LZMA1 or LZMA2 encoder has been
          optimized. (The speed of reinitializing an already-allocated
          encoder isn't affected.) This helps when compressing many
          small buffers with lzma_stream_buffer_encode() and other
          similar situations where an already-allocated encoder state
          isn't reused. This speed-up is visible in xz too if one
          compresses many small files one at a time instead running xz
          once and giving all files as command-line arguments.

        - Buffer comparisons are now much faster when unaligned access
          is allowed (configured with --enable-unaligned-access). This
          speeds up encoding significantly. There is arch-specific code
          for 32-bit and 64-bit x86 (32-bit needs SSE2 for the best
          results and there's no run-time CPU detection for now).
          For other archs there is only generic code which probably
          isn't as optimal as arch-specific solutions could be.

        - A few speed optimizations were made to the SHA-256 code.
          (Note that the builtin SHA-256 code isn't used on all
          operating systems.)

    * liblzma can now be built with MSVC 2013 update 2 or later
      using windows/config.h.

    * Vietnamese translation was added.


5.1.3alpha (2013-10-26)

    * All fixes from 5.0.5

    * liblzma:

        - Fixed a deadlock in the threaded encoder.

        - Made the uses of lzma_allocator const correct.

        - Added lzma_block_uncomp_encode() to create uncompressed
          .xz Blocks using LZMA2 uncompressed chunks.

        - Added support for native threads on Windows and the ability
          to detect the number of CPU cores.

    * xz:

        - Fixed a race condition in the signal handling. It was
          possible that e.g. the first SIGINT didn't make xz exit
          if reading or writing blocked and one had bad luck. The fix
          is non-trivial, so as of writing it is unknown if it will be
          backported to the v5.0 branch.

        - Made the progress indicator work correctly in threaded mode.

        - Threaded encoder now works together with --block-list=SIZES.

        - Added preliminary support for --flush-timeout=TIMEOUT.
          It can be useful for (somewhat) real-time streaming. For
          now the decompression side has to be done with something
          else than the xz tool due to how xz does buffering, but this
          should be fixed.


5.1.2alpha (2012-07-04)

    * All fixes from 5.0.3 and 5.0.4

    * liblzma:

        - Fixed a deadlock and an invalid free() in the threaded encoder.

        - Added support for symbol versioning. It is enabled by default
          on GNU/Linux, other GNU-based systems, and FreeBSD.

        - Use SHA-256 implementation from the operating system if one is
          available in libc, libmd, or libutil. liblzma won't use e.g.
          OpenSSL or libgcrypt to avoid introducing new dependencies.

        - Fixed liblzma.pc for static linking.

        - Fixed a few portability bugs.

    * xz --decompress --single-stream now fixes the input position after
      successful decompression. Now the following works:

          echo foo | xz > foo.xz
          echo bar | xz >> foo.xz
          ( xz -dc --single-stream ; xz -dc --single-stream ) < foo.xz

      Note that it doesn't work if the input is not seekable
      or if there is Stream Padding between the concatenated
      .xz Streams.

    * xz -lvv now shows the minimum xz version that is required to
      decompress the file. Currently it is 5.0.0 for all supported .xz
      files except files with empty LZMA2 streams require 5.0.2.

    * Added an *incomplete* implementation of --block-list=SIZES to xz.
      It only works correctly in single-threaded mode and when
      --block-size isn't used at the same time. --block-list allows
      specifying the sizes of Blocks which can be useful e.g. when
      creating files for random-access reading.


5.1.1alpha (2011-04-12)

    * All fixes from 5.0.2

    * liblzma fixes that will also be included in 5.0.3:

        - A memory leak was fixed.

        - lzma_stream_buffer_encode() no longer creates an empty .xz
          Block if encoding an empty buffer. Such an empty Block with
          LZMA2 data would trigger a bug in 5.0.1 and older (see the
          first bullet point in 5.0.2 notes). When releasing 5.0.2,
          I thought that no encoder creates this kind of files but
          I was wrong.

        - Validate function arguments better in a few functions. Most
          importantly, specifying an unsupported integrity check to
          lzma_stream_buffer_encode() no longer creates a corrupt .xz
          file. Probably no application tries to do that, so this
          shouldn't be a big problem in practice.

        - Document that lzma_block_buffer_encode(),
          lzma_easy_buffer_encode(), lzma_stream_encoder(), and
          lzma_stream_buffer_encode() may return LZMA_UNSUPPORTED_CHECK.

        - The return values of the _memusage() functions are now
          documented better.

    * Support for multithreaded compression was added using the simplest
      method, which splits the input data into blocks and compresses
      them independently. Other methods will be added in the future.
      The current method has room for improvement, e.g. it is possible
      to reduce the memory usage.

    * Added the options --single-stream and --block-size=SIZE to xz.

    * xzdiff and xzgrep now support .lzo files if lzop is installed.
      The .tzo suffix is also recognized as a shorthand for .tar.lzo.

    * Support for short 8.3 filenames under DOS was added to xz. It is
      experimental and may change before it gets into a stable release.


5.0.8 (2014-12-21)

    * Fixed an old bug in xzgrep that affected OpenBSD and probably
      a few other operating systems too.

    * Updated French and German translations.

    * Added support for detecting the amount of RAM on AmigaOS/AROS.

    * Minor build system updates.


5.0.7 (2014-09-20)

    * Fix regressions introduced in 5.0.6:

        - Fix building with non-GNU make.

        - Fix invalid Libs.private value in liblzma.pc which broke
          static linking against liblzma if the linker flags were
          taken from pkg-config.


5.0.6 (2014-09-14)

    * xzgrep now exits with status 0 if at least one file matched.

    * A few minor portability and build system fixes


5.0.5 (2013-06-30)

    * lzmadec and liblzma's lzma_alone_decoder(): Support decompressing
      .lzma files that have less common settings in the headers
      (dictionary size other than 2^n or 2^n + 2^(n-1), or uncompressed
      size greater than 256 GiB). The limitations existed to avoid false
      positives when detecting .lzma files. The lc + lp <= 4 limitation
      still remains since liblzma's LZMA decoder has that limitation.

      NOTE: xz's .lzma support or liblzma's lzma_auto_decoder() are NOT
      affected by this change. They still consider uncommon .lzma headers
      as not being in the .lzma format. Changing this would give way too
      many false positives.

    * xz:

        - Interaction of preset and custom filter chain options was
          made less illogical. This affects only certain less typical
          uses cases so few people are expected to notice this change.

          Now when a custom filter chain option (e.g. --lzma2) is
          specified, all preset options (-0 ... -9, -e) earlier are on
          the command line are completely forgotten. Similarly, when
          a preset option is specified, all custom filter chain options
          earlier on the command line are completely forgotten.

          Example 1: "xz -9 --lzma2=preset=5 -e" is equivalent to "xz -e"
          which is equivalent to "xz -6e". Earlier -e didn't put xz back
          into preset mode and thus the example command was equivalent
          to "xz --lzma2=preset=5".

          Example 2: "xz -9e --lzma2=preset=5 -7" is equivalent to
          "xz -7". Earlier a custom filter chain option didn't make
          xz forget the -e option so the example was equivalent to
          "xz -7e".

        - Fixes and improvements to error handling.

        - Various fixes to the man page.

    * xzless: Fixed to work with "less" versions 448 and later.

    * xzgrep: Made -h an alias for --no-filename.

    * Include the previously missing debug/translation.bash which can
      be useful for translators.

    * Include a build script for Mac OS X. This has been in the Git
      repository since 2010 but due to a mistake in Makefile.am the
      script hasn't been included in a release tarball before.


5.0.4 (2012-06-22)

    * liblzma:

        - Fix lzma_index_init(). It could crash if memory allocation
          failed.

        - Fix the possibility of an incorrect LZMA_BUF_ERROR when a BCJ
          filter is used and the application only provides exactly as
          much output space as is the uncompressed size of the file.

        - Fix a bug in doc/examples_old/xz_pipe_decompress.c. It didn't
          check if the last call to lzma_code() really returned
          LZMA_STREAM_END, which made the program think that truncated
          files are valid.

        - New example programs in doc/examples (old programs are now in
          doc/examples_old). These have more comments and more detailed
          error handling.

    * Fix "xz -lvv foo.xz". It could crash on some corrupted files.

    * Fix output of "xz --robot -lv" and "xz --robot -lvv" which
      incorrectly printed the filename also in the "foo (x/x)" format.

    * Fix exit status of "xzdiff foo.xz bar.xz".

    * Fix exit status of "xzgrep foo binary_file".

    * Fix portability to EBCDIC systems.

    * Fix a configure issue on AIX with the XL C compiler. See INSTALL
      for details.

    * Update French, German, Italian, and Polish translations.


5.0.3 (2011-05-21)

    * liblzma fixes:

        - A memory leak was fixed.

        - lzma_stream_buffer_encode() no longer creates an empty .xz
          Block if encoding an empty buffer. Such an empty Block with
          LZMA2 data would trigger a bug in 5.0.1 and older (see the
          first bullet point in 5.0.2 notes). When releasing 5.0.2,
          I thought that no encoder creates this kind of files but
          I was wrong.

        - Validate function arguments better in a few functions. Most
          importantly, specifying an unsupported integrity check to
          lzma_stream_buffer_encode() no longer creates a corrupt .xz
          file. Probably no application tries to do that, so this
          shouldn't be a big problem in practice.

        - Document that lzma_block_buffer_encode(),
          lzma_easy_buffer_encode(), lzma_stream_encoder(), and
          lzma_stream_buffer_encode() may return LZMA_UNSUPPORTED_CHECK.

        - The return values of the _memusage() functions are now
          documented better.

    * Fix command name detection in xzgrep. xzegrep and xzfgrep now
      correctly use egrep and fgrep instead of grep.

    * French translation was added.


5.0.2 (2011-04-01)

    * LZMA2 decompressor now correctly accepts LZMA2 streams with no
      uncompressed data. Previously it considered them corrupt. The
      bug can affect applications that use raw LZMA2 streams. It is
      very unlikely to affect .xz files because no compressor creates
      .xz files with empty LZMA2 streams. (Empty .xz files are a
      different thing than empty LZMA2 streams.)

    * "xz --suffix=.foo filename.foo" now refuses to compress the
      file due to it already having the suffix .foo. It was already
      documented on the man page, but the code lacked the test.

    * "xzgrep -l foo bar.xz" works now.

    * Polish translation was added.


5.0.1 (2011-01-29)

    * xz --force now (de)compresses files that have setuid, setgid,
      or sticky bit set and files that have multiple hard links.
      The man page had it documented this way already, but the code
      had a bug.

    * gzip and bzip2 support in xzdiff was fixed.

    * Portability fixes

    * Minor fix to Czech translation


5.0.0 (2010-10-23)

    Only the most important changes compared to 4.999.9beta are listed
    here. One change is especially important:

      * The memory usage limit is now disabled by default. Some scripts
        written before this change may have used --memory=max on xz command
        line or in XZ_OPT. THESE USES OF --memory=max SHOULD BE REMOVED
        NOW, because they interfere with user's ability to set the memory
        usage limit himself. If user-specified limit causes problems to
        your script, blame the user.

    Other significant changes:

      * Added support for XZ_DEFAULTS environment variable. This variable
        allows users to set default options for xz, e.g. default memory
        usage limit or default compression level. Scripts that use xz
        must never set or unset XZ_DEFAULTS. Scripts should use XZ_OPT
        instead if they need a way to pass options to xz via an
        environment variable.

      * The compression settings associated with the preset levels
        -0 ... -9 have been changed. --extreme was changed a little too.
        It is now less likely to make compression worse, but with some
        files the new --extreme may compress slightly worse than the old
        --extreme.

      * If a preset level (-0 ... -9) is specified after a custom filter
        chain options have been used (e.g. --lzma2), the custom filter
        chain will be forgotten. Earlier the preset options were
        completely ignored after custom filter chain options had been
        seen.

      * xz will create sparse files when decompressing if the uncompressed
        data contains long sequences of binary zeros. This is done even
        when writing to standard output that is connected to a regular
        file and certain additional conditions are met to make it safe.

      * Support for "xz --list" was added. Combine with --verbose or
        --verbose --verbose (-vv) for detailed output.

      * I had hoped that liblzma API would have been stable after
        4.999.9beta, but there have been a couple of changes in the
        advanced features, which don't affect most applications:

          - Index handling code was revised. If you were using the old
            API, you will get a compiler error (so it's easy to notice).

          - A subtle but important change was made to the Block handling
            API. lzma_block.version has to be initialized even for
            lzma_block_header_decode(). Code that doesn't do it will work
            for now, but might break in the future, which makes this API
            change easy to miss.

      * The major soname has been bumped to 5.0.0. liblzma API and ABI
        are now stable, so the need to recompile programs linking against
        liblzma shouldn't arise soon.