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Compatibility for ffi builds

• Fixed LZ77 to comply with the specification
  • No longer seed the context by the end of the lz77 dictionary. Instead usezero for the seed as would happen without a dictionary. This matches thebehavior of brotli with a custom dictionary as specified in
  • https://datatracker.ietf.org/doc/draft-vandevenne-shared-brotli-format/

• Fix error with short writes
• allow quality=10 for certain APIs and make it default to 9.5

• Remove unused SIMD use statements
• hide a few warnings - these are TODOs, and should be fixed in separate PRs
• do NOT build SIMD as part of MSRV -- doesn't make any sense to combine nightly with MSRV

• The FFI is no longer active by default to avoid ODR issues if multiple versions of brotli are included in several dependent crates.

Pinned to a rust-brotli-decompressor that can disable the ffi with the ffi-apiflag.This can help avoid symbol conflicts with other brotli libs.

Updated SIMD support.Better CI integration.Cleaned up some of the clippy warnings.

Brotli decompressor's reader and writer has better behavior when operating upon brotli streams with extra bits at the end.Optional features like stdsimd are now tested or disabled for now.

• into_inner conversions for both Reader and Writer classes

• A fully compatible FFI for drop-in compatibiltiy with thehttps://github.com/google/brotli binaries
  • custom allocators fully supported
• Multithreaded compression so multiple threads can operate in unison on a single file
• Concatenatability mode to add the feature requested ingoogle/brotli#628
  • binary tool catbrotli can accomplish this if the first file was specified with -apendable and the second with -catable
• validation mode where a file is double-checked to be able to be decompressed with the same settings; useful for benchmarking or fuzzing
• Magic Number: where the brotli file can have a useful header with a few magic bytes, concatability info and a final output size for pre-allocating memory

• In 2.5 The callback also passes down an allocator to make new StaticCommands and PDFs and 256 bit floating point vectors.
• In 2.4 The callback with the compression intermediate representation now passes a full metablock at a time. Also these items are mutablein case futher optimization is desired

• Flush now produces output instead of calling finish on the stream. This allows you to use the writer abstraction toget immediate output without having to resort to the CompressStream internal abstraction

Direct no-stdlib port of the C brotli compressor to Rust

no dependency on the Rust stdlib: this library would be ideal for decompressing within a rust kernel among other things.

This is useful to see how C and Rust compare in an apples-to-applescomparison where the same algorithms and data structures andoptimizations are employed.

Rust brotli currently supports compression levels 0 - 11They should be bitwise identical to the brotli C compression engine at compression levels 0-9Recommended lg_window_size is between 20 and 22

letmut input = brotli::CompressorReader::new(&mut io::stdin(),4096/* buffer size */,                                              qualityasu32, lg_window_sizeasu32);

then you can simply read input as you would any other io::Read class

letmut writer = brotli::Compressor::new(&mut io::stdout(),4096/* buffer size */,                                         qualityasu32, lg_window_sizeasu32);

There are also methods to build Compressor Readers or Writers using the with_params static function

eg:

let params =BrotliEncoderParams::default();// modify params to fit the application needsletmut writer = brotli::Compressor::with_params(&mut io::stdout(),4096/* buffer size */,                                         params);

or for the reader

let params =BrotliEncoderParams::default();// modify params to fit the application needsletmut writer = brotli::CompressorReader::with_params(&mut io::stdin(),4096/* buffer size */,                                                       params);

match brotli::BrotliCompress(&mut io::stdin(),&mut io::stdout(),&brotli_encoder_params){Ok(_) =>{},Err(e) =>panic!("Error {:?}", e),}

letmut input = brotli::Decompressor::new(&mut io::stdin(),4096/* buffer size */);

then you can simply read input as you would any other io::Read class

letmut writer = brotli::DecompressorWriter::new(&mut io::stdout(),4096/* buffer size */);

match brotli::BrotliDecompress(&mut io::stdin(),&mut io::stdout()){Ok(_) =>{},Err(e) =>panic!("Error {:?}", e),}

There are 3 steps to using brotli without stdlib

1. setup the memory manager
2. setup the BrotliState
3. in a loop, call BrotliDecompressStream

in Detail

// at global scope declare a MemPool type -- in this case we'll choose the heap to// avoid unsafe code, and avoid restrictions of the stack sizedeclare_stack_allocator_struct!(MemPool, heap);// at local scope, make a heap allocated buffers to hold uint8's uint32's and huffman codesletmut u8_buffer =define_allocator_memory_pool!(4096,u8,[0;32*1024*1024], heap);letmut u32_buffer =define_allocator_memory_pool!(4096,u32,[0;1024*1024], heap);letmut hc_buffer =define_allocator_memory_pool!(4096,HuffmanCode,[0;4*1024*1024], heap);let heap_u8_allocator =HeapPrealloc::<u8>::new_allocator(4096,&mut u8_buffer, bzero);let heap_u32_allocator =HeapPrealloc::<u32>::new_allocator(4096,&mut u32_buffer, bzero);let heap_hc_allocator =HeapPrealloc::<HuffmanCode>::new_allocator(4096,&mut hc_buffer, bzero);// At this point no more syscalls are going to be needed since everything can come from the allocators.// Feel free to activate SECCOMP jailing or other mechanisms to secure your application if you wish.// Now it's possible to setup the decompressor stateletmut brotli_state =BrotliState::new(heap_u8_allocator, heap_u32_allocator, heap_hc_allocator);// at this point the decompressor simply needs an input and output buffer and the ability to track// the available data left in each bufferloop{    result =BrotliDecompressStream(&mut available_in,&mut input_offset,&input.slice(),&mut available_out,&mut output_offset,&mut output.slice_mut(),&mut written,&mut brotli_state);// just end the decompression if result is BrotliResult::ResultSuccess or BrotliResult::ResultFailure}

This interface is the same interface that the C brotli decompressor uses

Also feel free to use custom allocators that invoke Box directly.This example illustrates a mechanism to avoid subsequent syscalls after the initial allocation

rust-brotli is a drop-in replacement for the officialhttps://github.com/google/brotli Cimplementation. That means you can use it from any place that supports that library.To build rust-brotli in this manner enter the c subdirectory and run make there

cd c && make

this should build c/target/release/libbrotli.so and should build the vanillacommand line tool in C for compressing and decompressing any brotli file.

the libbrotli.so in c/target/release should be able to replace any other libbrotli.sofile, but with all the advantages of using safe rust (except in the FFI bindings)

The code also allows a wider range of options, including forcing the prediction mode(eg UTF8 vs signed vs MSB vs LSB) and changing the weight of the literal cost from 540to other values.

Additionally the CATABLE and APPENDABLE options are exposed and allow concatenation of filescreated in this manner.

Specifically CATABLE files can be concatenated in any order using the catbrotli tooland APPENDABLE files can be the first file in a sequence of catable files...eg you can combineappendable.br catable1.br catable2.br catable3.br

or simplycatable0.br catable1.br catable2.br catable3.br