Caleb Gardner
77 lines
1.8 KiB
Go
77 lines
1.8 KiB
Go
package compression
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import (
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"bytes"
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"encoding/binary"
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"io"
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"github.com/klauspost/compress/zlib"
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)
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type gzipInit struct {
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CompressionLevel int32
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WindowSize int16
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Strategies int16
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}
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//Gzip is a decompressor for gzip type compression. Uses zlib for compression and decompression
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type Gzip struct {
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wrt *zlib.Writer
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gzipInit
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HasCustomWindow bool
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HasStrategies bool
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}
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//NewGzipCompressorWithOptions creates a new gzip compressor/decompressor with options read from the given reader.
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func NewGzipCompressorWithOptions(r io.Reader) (*Gzip, error) {
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var gzip Gzip
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err := binary.Read(r, binary.LittleEndian, &gzip.gzipInit)
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if err != nil {
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return nil, err
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}
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//TODO: proper support for window size and strategies
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gzip.HasCustomWindow = gzip.WindowSize != 15
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gzip.HasStrategies = gzip.Strategies != 0 && gzip.Strategies != 1
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return &gzip, nil
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}
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//Decompress reads the entirety of the given reader and returns it uncompressed as a byte slice.
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func (g *Gzip) Decompress(r io.Reader) ([]byte, error) {
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rdr, err := zlib.NewReader(r)
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if err != nil {
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return nil, err
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}
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var data bytes.Buffer
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_, err = io.Copy(&data, rdr)
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if err != nil {
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return nil, err
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}
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return data.Bytes(), nil
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}
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//Compress compresses the given data (as a byte array) and returns the compressed data.
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func (g *Gzip) Compress(data []byte) ([]byte, error) {
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var buf bytes.Buffer
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var err error
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if g.wrt == nil {
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if g.CompressionLevel == 0 {
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g.wrt = zlib.NewWriter(&buf)
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} else {
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g.wrt, err = zlib.NewWriterLevel(&buf, int(g.CompressionLevel))
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if err != nil {
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return nil, err
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}
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}
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}
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wrt, err := zlib.NewWriterLevel(&buf, int(g.CompressionLevel))
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if err != nil {
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return nil, err
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}
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_, err = wrt.Write(data)
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if err != nil {
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return nil, err
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}
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wrt.Close()
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return buf.Bytes(), nil
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}
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