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