6ad3a983db
The bug would make the bt search read one byte in an invalid memory region, and make a branch decision based on its value. Impact was small (missed compression opportunity). It only happens in -BD mode, with extDict-prefix overlapping matches. The bt match search is supposed to work also in extDict mode. In which case, the match ptr can point into Dict. When the match was overlapping Dict<->Prefix, match[matchLength] would end up outside of Dict, in an invalid memory area. The correction ensures that in such a case, match[matchLength] ends up at intended location, inside prefix. |
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|---|---|---|
| .. | ||
| dll | ||
| .gitignore | ||
| liblz4.pc.in | ||
| LICENSE | ||
| lz4.c | ||
| lz4.h | ||
| lz4frame_static.h | ||
| lz4frame.c | ||
| lz4frame.h | ||
| lz4hc.c | ||
| lz4hc.h | ||
| lz4opt.h | ||
| Makefile | ||
| README.md | ||
| xxhash.c | ||
| xxhash.h | ||
LZ4 - Library Files
The directory contains many files, but depending on project's objectives, not all of them are necessary.
Minimal LZ4 build
The minimum required is lz4.c and lz4.h,
which will provide the fast compression and decompression algorithm.
The High Compression variant of LZ4
For more compression at the cost of compression speed,
the High Compression variant lz4hc is available.
It's necessary to add lz4hc.c and lz4hc.h.
The variant still depends on regular lz4 source files.
In particular, the decompression is still provided by lz4.c.
Compatibility issues
In order to produce files or streams compatible with lz4 command line utility,
it's necessary to encode lz4-compressed blocks using the official interoperable frame format.
This format is generated and decoded automatically by the lz4frame library.
In order to work properly, lz4frame needs lz4 and lz4hc, and also xxhash,
which provides error detection.
(Advanced stuff : It's possible to hide xxhash symbols into a local namespace.
This is what liblz4 does, to avoid symbol duplication
in case a user program would link to several libraries containing xxhash symbols.)
Advanced API
A more complex lz4frame_static.h is also provided.
It contains definitions which are not guaranteed to remain stable within future versions.
It must be used with static linking only.
Using MinGW+MSYS to create DLL
DLL can be created using MinGW+MSYS with the make liblz4 command.
This command creates dll\liblz4.dll and the import library dll\liblz4.lib.
The import library is only required with Visual C++.
The header files lz4.h, lz4hc.h, lz4frame.h and the dynamic library
dll\liblz4.dll are required to compile a project using gcc/MinGW.
The dynamic library has to be added to linking options.
It means that if a project that uses LZ4 consists of a single test-dll.c
file it should be linked with dll\liblz4.dll. For example:
gcc $(CFLAGS) -Iinclude/ test-dll.c -o test-dll dll\liblz4.dll
The compiled executable will require LZ4 DLL which is available at dll\liblz4.dll.
Miscellaneous
Other files present in the directory are not source code. There are :
- LICENSE : contains the BSD license text
- Makefile : script to compile or install lz4 library (static or dynamic)
- liblz4.pc.in : for pkg-config (make install)
- README.md : this file
License
All source material within lib directory are BSD 2-Clause licensed. See LICENSE for details. The license is also repeated at the top of each source file.