Rebol/Bzip2

Bzip2 compression extension for Rebol3 (version 3.20.5 and higher)

Basic usage

Use Bzip2 as a codec for the standard compress and decompress functions:

import bzip2
bin: compress "some data" 'bzip2
txt: to string! decompress bin 'bzip2

Installation

Build the extension using Siskin and copy the produced .rebx into your Rebol modules directory.

# Build (Linux x64 example)
./siskin Rebol-Bzip2.nest static-lib-x64
./siskin Rebol-Bzip2.nest bzip2-linux-x64
mv ./build/bzip2-linux-x64.so ./bzip2.rebx

# Install
mkdir -p ~/.rebol/modules
cp -f ./bzip2.rebx ~/.rebol/modules/bzip2.rebx

If you see invalid ELF header, you likely installed the wrong file (e.g. the static archive libbzip2-*.a) instead of the extension .rebx.

Streaming API

Incremental compression uses libbzip2 bz_stream handles (make-encoder, make-decoder, write, read). Output is accumulated on the handle until you call write with /flush or /finish (encoder), which returns a copy of the pending compressed binary and clears the buffer—similar to Rebol-Zstd.

bzip2: import 'bzip2
enc: bzip2/make-encoder
bzip2/write :enc "Hello "
bzip2/write :enc "World"
bin: bzip2/write/finish :enc "!"
text: to string! decompress bin 'bzip2
;== "Hello World!"

dec: bzip2/make-decoder
bzip2/write :dec bin
plain: to string! bzip2/read :dec

For large inputs you can feed the decoder in multiple write calls (splitting the compressed binary at byte boundaries is fine once the stream is valid).

Extension commands:

version

Libbzip2 version string (BZ2_bzlibVersion)

compress :data

Compress data using bzip2

• data [binary! any-string!] Input data to compress.
• /part Limit the input data to a given length.
• length [integer!] Length of input data.
• /level
• quality [integer!] Block size 100k: 1 (fast) to 9 (best).

decompress :data

Decompress bzip2 data

• data [binary! any-string!] Input data to decompress.
• /part Limit the input data to a given length.
• length [integer!] Length of input data.
• /size Limit the output size.
• bytes [integer!] Maximum number of uncompressed bytes.
• /max Cap allocated output (ZIP bomb guard).
• ceiling [integer!] Maximum bytes to allocate while decompressing.

make-encoder

Create a new bzip2 encoder handle.

• /level
• quality [integer!] Block size 100k: 1 (fast) to 9 (best).

make-decoder

Create a new bzip2 decoder handle.

write :codec :data

Feed data into a bzip2 streaming codec.

• codec [handle!] Encoder or decoder handle.
• data [binary! any-string! none!] Data to compress or decompress, or NONE to finish encoder output.
• /flush Flush encoder output (BZ_FLUSH).
• /finish Finish encoder stream (BZ_FINISH).

read :codec

Retrieve pending data from the codec buffer.

• codec [handle!]