README

HISTORY of the LZMA SDK
-----------------------

23.01          2023-06-20
-------------------------
- 7-Zip now can use new ARM64 filter for compression to 7z and xz archives.
  ARM64 filter can increase compression ratio for data containing executable 
  files compiled for ARM64 (AArch64) architecture.
  Also 7-Zip now parses executable files (that have exe and dll filename extensions) 
  before compressing, and it selects appropriate filter for each parsed file: 
    - BCJ or BCJ2 filter for x86 executable files,
    - ARM64 filter for ARM64 executable files.
  Previous versions by default used x86 filter BCJ or BCJ2 for all exe/dll files.
- Default section size for BCJ2 filter was changed from 64 MiB to 240 MiB.
  It can increase compression ratio for executable files larger than 64 MiB.
- Some optimizations in filters code: BCJ, BCJ2, Swap* and opthers.
- If 7-Zip uses BCJ2 filter for big datasets compressing, it can use additional temp 
  files in system's TEMP folder. 7-Zip uses temp file for additional compressed 
  data stream, if size of such compressed stream is larger than predefined limit: 
  16 MiB in 32-bit version, 4 GiB in 64-bit version.
- When new 7-Zip creates multivolume archive, 7-Zip keeps in open state
  only volumes that still can be changed. Previous versions kept all volumes 
  in open state until the end of the archive creation.
- 7-Zip for Linux and macOS now can reduce the number of simultaneously open files,
  when 7-Zip opens, extracts or creates multivolume archive. It allows to avoid 
  the failures for cases with big number of volumes, bacause there is a limitation 
  for number of open files allowed for a single program in Linux and macOS.
- Some bugs were fixed.
- Source code changes:
- All external macros for compiling C/C++ code of 7-Zip now have Z7_ prefix.
- 7-Zip COM interfaces now use new macros that allow to declare and implement COM interface.
- The code has been modified to compile with the maximum diagnostic warning level:
    -Wall in MSVC and -Weverything in CLANG.
  And some warning types are disabled in 2 files:
    - C/Compiler.h for C/C++ code warnings.
    - CPP/Common/Common.h for C++ code warnings.
- Linux/macOS versions of 7-Zip: IUnknown interface in new code doesn't use 
  virtual destructor that was used in previous 7-Zip and p7zip:
     // virtual ~IUnknown() {}
  So 7-Zip's dynamically linked shared libraries (codecs) are not compatible 
  between new 7-Zip for Linux/macOS and old 7-Zip (and p7zip).


21.07          2021-12-26
-------------------------
- New switches: -spm and -im!{file_path} to exclude directories from processing 
    for specified paths that don't contain path separator character at the end of path.
- The sorting order of files in archives was slightly changed to be more consistent
  for cases where the name of some directory is the same as the prefix part of the name
  of another directory or file.


21.06          2021-11-24
-------------------------
- Bug in LZMA encoder in file LzmaEnc.c was fixed:
  LzmaEnc_MemEncode(), LzmaEncode() and LzmaCompress() could work incorrectly, 
    if size value for output buffer is smaller than size required for all compressed data.
  LzmaEnc_Encode() could work incorrectly,
    if callback ISeqOutStream::Write() doesn't write all compressed data.
  NCompress::NLzma::CEncoder::Code() could work incorrectly,
    if callback ISequentialOutStream::Write() returns error code.
- Bug in versions 21.00-21.05 was fixed:
  7-Zip didn't set attributes of directories during archive extracting.


21.04 beta     2021-11-02
-------------------------
- 7-Zip now reduces the number of working CPU threads for compression,
  if RAM size is not enough for compression with big LZMA2 dictionary.
- 7-Zip now can create and check "file.sha256" text files that contain the list 
  of file names and SHA-256 checksums in format compatible with sha256sum program.


21.03 beta     2021-07-20
-------------------------
- The maximum dictionary size for LZMA/LZMA2 compressing was increased to 4 GB (3840 MiB).
- Minor speed optimizations in LZMA/LZMA2 compressing.


21.02 alpha    2021-05-06
-------------------------
- The command line version of 7-Zip for macOS was released.
- The speed for LZMA and LZMA2 decompression in arm64 versions for macOS and Linux 
  was increased by 20%-60%.


21.01 alpha    2021-03-09
-------------------------
- The command line version of 7-Zip for Linux was released.
- The improvements for speed of ARM64 version using hardware CPU instructions 
  for AES, CRC-32, SHA-1 and SHA-256.
- Some bugs were fixed.


20.02 alpha    2020-08-08
-------------------------
- The default number of LZMA2 chunks per solid block in 7z archive was increased to 64.
  It allows to increase the compression speed for big 7z archives, if there is a big number 
  of CPU cores and threads.
- The speed of PPMd compressing/decompressing was increased for 7z archives.
- The new -ssp switch. If the switch -ssp is specified, 7-Zip doesn't allow the system 
  to modify "Last Access Time" property of source files for archiving and hashing operations. 
- Some bugs were fixed.


20.00 alpha    2020-02-06
-------------------------
- 7-Zip now supports new optional match finders for LZMA/LZMA2 compression: bt5 and hc5, 
  that can work faster than bt4 and hc4 match finders for the data with big redundancy.
- The compression ratio was improved for Fast and Fastest compression levels with the 
  following default settings:
   - Fastest level (-mx1) : hc5 match finder with 256 KB dictionary.
   - Fast    level (-mx3) : hc5 match finder with 4 MB dictionary.
- Minor speed optimizations in multithreaded LZMA/LZMA2 compression for Normal/Maximum/Ultra 
  compression levels.


19.00          2019-02-21
-------------------------
- Encryption strength for 7z archives was increased:
  the size of random initialization vector was increased from 64-bit to 128-bit,
  and the pseudo-random number generator was improved.
- The bug in 7zIn.c code was fixed.


18.06          2018-12-30
-------------------------
- The speed for LZMA/LZMA2 compressing was increased by 3-10%,
  and there are minor changes in compression ratio.
- Some bugs were fixed.
- The bug in 7-Zip 18.02-18.05 was fixed:
  There was memory leak in multithreading xz decoder - XzDecMt_Decode(),
  if xz stream contains only one block.
- The changes for MSVS compiler makefiles: 
   - the makefiles now use "PLATFORM" macroname with values (x64, x86, arm64)
     instead of "CPU" macroname with values (AMD64, ARM64).
   - the makefiles by default now use static version of the run-time library.


18.05          2018-04-30
-------------------------
- The speed for LZMA/LZMA2 compressing was increased 
    by 8% for fastest/fast compression levels and 
    by 3% for normal/maximum compression levels.
- Previous versions of 7-Zip could work incorrectly in "Large memory pages" mode in
  Windows 10 because of some BUG with "Large Pages" in Windows 10. 
  Now 7-Zip doesn't use "Large Pages" on Windows 10 up to revision 1709 (16299).
- The BUG was fixed in Lzma2Enc.c
    Lzma2Enc_Encode2() function worked incorretly,
      if (inStream == NULL) and the number of block threads is more than 1.


18.03 beta     2018-03-04
-------------------------
- Asm\x86\LzmaDecOpt.asm: new optimized LZMA decoder written in asm 
  for x64 with about 30% higher speed than main version of LZMA decoder written in C.
- The speed for single-thread LZMA/LZMA2 decoder written in C was increased by 3%.
- 7-Zip now can use multi-threading for 7z/LZMA2 decoding,
  if there are multiple independent data chunks in LZMA2 stream.
- 7-Zip now can use multi-threading for xz decoding,
  if there are multiple blocks in xz stream.


18.01          2019-01-28
-------------------------
- The BUG in 17.01 - 18.00 beta was fixed:
  XzDec.c : random block unpacking and XzUnpacker_IsBlockFinished()
  didn't work correctly for xz archives without checksum (CRC).


18.00 beta     2019-01-10
-------------------------
- The BUG in xz encoder was fixed:
  There was memory leak of 16 KB for each file compressed with 
  xz compression method, if additional filter was used.


17.01 beta     2017-08-28
-------------------------
- Minor speed optimization for LZMA2 (xz and 7z) multi-threading compression.
  7-Zip now uses additional memory buffers for multi-block LZMA2 compression.
  CPU utilization was slightly improved.
- 7-zip now creates multi-block xz archives by default. Block size can be 
  specified with -ms[Size]{m|g} switch.
- xz decoder now can unpack random block from multi-block xz archives.
- 7-Zip command line: @listfile now doesn't work after -- switch.
  Use -i@listfile before -- switch instead.
- The BUGs were fixed:
  7-Zip 17.00 beta crashed for commands that write anti-item to 7z archive.


17.00 beta     2017-04-29
-------------------------
- NewHandler.h / NewHandler.cpp: 
    now it redefines operator new() only for old MSVC compilers (_MSC_VER < 1900).
- C/7zTypes.h : the names of variables in interface structures were changed (vt).
- Some bugs were fixed. 7-Zip could crash in some cases.
- Some internal changes in code.


16.04          2016-10-04
-------------------------
- The bug was fixed in DllSecur.c.


16.03          2016-09-28
-------------------------
- SFX modules now use some protection against DLL preloading attack.
- Some bugs in 7z code were fixed.


16.02          2016-05-21
-------------------------
- The BUG in 16.00 - 16.01 was fixed:
  Split Handler (SplitHandler.cpp) returned incorrect 
  total size value (kpidSize) for split archives.


16.01          2016-05-19
-------------------------	
- Some internal changes to reduce the number of compiler warnings.


16.00          2016-05-10
-------------------------	
- Some bugs were fixed.


15.12          2015-11-19
-------------------------	
- The BUG in C version of 7z decoder was fixed:
  7zDec.c : SzDecodeLzma2()
  7z decoder could mistakenly report about decoding error for some 7z archives
  that use LZMA2 compression method.
  The probability to get that mistaken decoding error report was about 
  one error per 16384 solid blocks for solid blocks larger than 16 KB (compressed size). 
- The BUG (in 9.26-15.11) in C version of 7z decoder was fixed:
  7zArcIn.c : SzReadHeader2()
  7z decoder worked incorrectly for 7z archives that contain 
  empty solid blocks, that can be placed to 7z archive, if some file is 
  unavailable for reading during archive creation.


15.09 beta     2015-10-16
-------------------------	
- The BUG in LZMA / LZMA2 encoding code was fixed.
  The BUG in LzFind.c::MatchFinder_ReadBlock() function.
  If input data size is larger than (4 GiB - dictionary_size),
  the following code worked incorrectly:
  -  LZMA : LzmaEnc_MemEncode(), LzmaEncode() : LZMA encoding functions 
     for compressing from memory to memory. 
     That BUG is not related to LZMA encoder version that works via streams.
  -  LZMA2 : multi-threaded version of LZMA2 encoder worked incorrectly, if 
     default value of chunk size (CLzma2EncProps::blockSize) is changed 
     to value larger than (4 GiB - dictionary_size).


9.38 beta      2015-01-03
-------------------------	
- The BUG in 9.31-9.37 was fixed:
  IArchiveGetRawProps interface was disabled for 7z archives.
- The BUG in 9.26-9.36 was fixed:
  Some code in CPP\7zip\Archive\7z\ worked correctly only under Windows.


9.36 beta      2014-12-26
-------------------------	
- The BUG in command line version was fixed:
  7-Zip created temporary archive in current folder during update archive
  operation, if -w{Path} switch was not specified. 
  The fixed 7-Zip creates temporary archive in folder that contains updated archive.
- The BUG in 9.33-9.35 was fixed:
  7-Zip silently ignored file reading errors during 7z or gz archive creation,
  and the created archive contained only part of file that was read before error.
  The fixed 7-Zip stops archive creation and it reports about error.


9.35 beta      2014-12-07
-------------------------	
- 7zr.exe now support AES encryption.
- SFX mudules were added to LZMA SDK
- Some bugs were fixed.


9.21 beta      2011-04-11
-------------------------	
- New class FString for file names at file systems.
- Speed optimization in CRC code for big-endian CPUs.
- The BUG in Lzma2Dec.c was fixed:
    Lzma2Decode function didn't work.


9.18 beta      2010-11-02
-------------------------	
- New small SFX module for installers (SfxSetup).


9.12 beta      2010-03-24
-------------------------
- The BUG in LZMA SDK 9.* was fixed: LZMA2 codec didn't work,
  if more than 10 threads were used (or more than 20 threads in some modes).


9.11 beta      2010-03-15
-------------------------
- PPMd compression method support
   

9.09           2009-12-12
-------------------------
- The bug was fixed:
   Utf16_To_Utf8 funstions in UTFConvert.cpp and 7zMain.c
   incorrectly converted surrogate characters (the code >= 0x10000) to UTF-8.
- Some bugs were fixed


9.06           2009-08-17
-------------------------
- Some changes in ANSI-C 7z Decoder interfaces.


9.04           2009-05-30
-------------------------
- LZMA2 compression method support
- xz format support


4.65           2009-02-03
-------------------------
- Some minor fixes


4.63           2008-12-31
-------------------------
- Some minor fixes


4.61 beta      2008-11-23
-------------------------
- The bug in ANSI-C LZMA Decoder was fixed:
    If encoded stream was corrupted, decoder could access memory 
    outside of allocated range.
- Some changes in ANSI-C 7z Decoder interfaces.
- LZMA SDK is placed in the public domain.


4.60 beta      2008-08-19
-------------------------
- Some minor fixes.


4.59 beta      2008-08-13
-------------------------
- The bug was fixed:
    LZMA Encoder in fast compression mode could access memory outside of 
    allocated range in some rare cases.


4.58 beta      2008-05-05
-------------------------
- ANSI-C LZMA Decoder was rewritten for speed optimizations.
- ANSI-C LZMA Encoder was included to LZMA SDK.
- C++ LZMA code now is just wrapper over ANSI-C code.


4.57           2007-12-12
-------------------------
- Speed optimizations in Ñ++ LZMA Decoder. 
- Small changes for more compatibility with some C/C++ compilers.


4.49 beta      2007-07-05
-------------------------
- .7z ANSI-C Decoder:
     - now it supports BCJ and BCJ2 filters
     - now it supports files larger than 4 GB.
     - now it supports "Last Write Time" field for files.
- C++ code for .7z archives compressing/decompressing from 7-zip 
  was included to LZMA SDK.
  

4.43           2006-06-04
-------------------------
- Small changes for more compatibility with some C/C++ compilers.
  

4.42           2006-05-15
-------------------------
- Small changes in .h files in ANSI-C version.
  

4.39 beta      2006-04-14
-------------------------
- The bug in versions 4.33b:4.38b was fixed:
  C++ version of LZMA encoder could not correctly compress 
  files larger than 2 GB with HC4 match finder (-mfhc4).
  

4.37 beta      2005-04-06
-------------------------
- Fixes in C++ code: code could no be compiled if _NO_EXCEPTIONS was defined. 


4.35 beta      2005-03-02
-------------------------
- The bug was fixed in C++ version of LZMA Decoder:
    If encoded stream was corrupted, decoder could access memory 
    outside of allocated range.


4.34 beta      2006-02-27
-------------------------
- Compressing speed and memory requirements for compressing were increased
- LZMA now can use only these match finders: HC4, BT2, BT3, BT4


4.32           2005-12-09
-------------------------
- Java version of LZMA SDK was included


4.30           2005-11-20
-------------------------
- Compression ratio was improved in -a2 mode
- Speed optimizations for compressing in -a2 mode
- -fb switch now supports values up to 273
- The bug in 7z_C (7zIn.c) was fixed:
  It used Alloc/Free functions from different memory pools.
  So if program used two memory pools, it worked incorrectly.
- 7z_C: .7z format supporting was improved
- LZMA# SDK (C#.NET version) was included


4.27 (Updated) 2005-09-21
-------------------------
- Some GUIDs/interfaces in C++ were changed.
 IStream.h:
   ISequentialInStream::Read now works as old ReadPart
   ISequentialOutStream::Write now works as old WritePart


4.27           2005-08-07
-------------------------
- The bug in LzmaDecodeSize.c was fixed:
   if _LZMA_IN_CB and _LZMA_OUT_READ were defined,
   decompressing worked incorrectly.


4.26           2005-08-05
-------------------------
- Fixes in 7z_C code and LzmaTest.c:
  previous versions could work incorrectly,
  if malloc(0) returns 0


4.23           2005-06-29
-------------------------
- Small fixes in C++ code


4.22           2005-06-10
-------------------------
- Small fixes


4.21           2005-06-08
-------------------------
- Interfaces for ANSI-C LZMA Decoder (LzmaDecode.c) were changed
- New additional version of ANSI-C LZMA Decoder with zlib-like interface:
    - LzmaStateDecode.h
    - LzmaStateDecode.c
    - LzmaStateTest.c
- ANSI-C LZMA Decoder now can decompress files larger than 4 GB


4.17           2005-04-18
-------------------------
- New example for RAM->RAM compressing/decompressing: 
  LZMA + BCJ (filter for x86 code):
    - LzmaRam.h
    - LzmaRam.cpp
    - LzmaRamDecode.h
    - LzmaRamDecode.c
    - -f86 switch for lzma.exe


4.16           2005-03-29
-------------------------
- The bug was fixed in LzmaDecode.c (ANSI-C LZMA Decoder): 
   If _LZMA_OUT_READ was defined, and if encoded stream was corrupted,
   decoder could access memory outside of allocated range.
- Speed optimization of ANSI-C LZMA Decoder (now it's about 20% faster).
  Old version of LZMA Decoder now is in file LzmaDecodeSize.c. 
  LzmaDecodeSize.c can provide slightly smaller code than LzmaDecode.c
- Small speed optimization in LZMA C++ code
- filter for SPARC's code was added
- Simplified version of .7z ANSI-C Decoder was included


4.06           2004-09-05
-------------------------
- The bug in v4.05 was fixed:
    LZMA-Encoder didn't release output stream in some cases.


4.05           2004-08-25
-------------------------
- Source code of filters for x86, IA-64, ARM, ARM-Thumb 
  and PowerPC code was included to SDK
- Some internal minor changes


4.04           2004-07-28
-------------------------
- More compatibility with some C++ compilers


4.03           2004-06-18
-------------------------
- "Benchmark" command was added. It measures compressing 
  and decompressing speed and shows rating values. 
  Also it checks hardware errors.


4.02           2004-06-10
-------------------------
- C++ LZMA Encoder/Decoder code now is more portable
  and it can be compiled by GCC on Linux.


4.01           2004-02-15
-------------------------
- Some detection of data corruption was enabled.
    LzmaDecode.c / RangeDecoderReadByte
    .....
    {
      rd->ExtraBytes = 1;
      return 0xFF;
    }


4.00           2004-02-13
-------------------------
- Original version of LZMA SDK



HISTORY of the LZMA
-------------------
  2001-2008:  Improvements to LZMA compressing/decompressing code, 
              keeping compatibility with original LZMA format
  1996-2001:  Development of LZMA compression format

  Some milestones:

  2001-08-30: LZMA compression was added to 7-Zip
  1999-01-02: First version of 7-Zip was released
  

End of document