Protobuf-LZMA

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Implements two classes for using with the open-source Protobuf C++ library, LzmaInputStream and LzmaOutputStream, that compress and decompress data using Igor Pavlov's public domain LZMA SDK. Achieved compression ratio is often twice as good as with GZip compression.

Compression is done per block of data (1MB by default, but it's configurable). Each block embeds a SHA-256 digest of the uncompressed data, so that it can be verified at decompression time. Such verification is entirely optional.

Compression settings, such as dictionary size or compression level, can be modified anytime and will affect the subsequent blocks.

This code is hereby released under New BSD license.

Limitations:

I'm using these classes for reading from and writing to local files with std::ifstream and std::ofstream, so there might be some problems when an entire block of data cannot be read or written at once. If you want to use them for I/O over a network connection, feel free to fix this issue and send me a pull request :)

Building the LZMA SDK:

Refer to its documentation. All you need if you want to encode using a single CPU core is LzFind.c, LzmaDec.c, LzmaEnc.c and Sha256.c. You will also need to append -D_7ZIP_ST (as in "Single Thread") to your CFLAGS.