0b2ae3a0ba
Add streaming compression wrappers that work with io.Writer/io.Reader instead of []byte. NewCompressWriter supports gz, xz, and passthrough (none/"") formats, returning an io.WriteCloser. Unknown formats return an error. Includes nopCloser type for the passthrough case. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
87 lines
1.9 KiB
Go
87 lines
1.9 KiB
Go
package compress
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import (
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"bytes"
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"compress/gzip"
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"fmt"
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"io"
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"github.com/ulikunitz/xz"
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)
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// nopCloser wraps an io.Writer with a no-op Close method.
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type nopCloser struct{ io.Writer }
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func (n *nopCloser) Close() error { return nil }
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// NewCompressWriter returns a streaming io.WriteCloser that compresses data
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// written to it into the underlying writer w using the specified format.
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// Supported formats: "gz" (gzip), "xz", "none" or "" (passthrough).
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// Unknown formats return an error.
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func NewCompressWriter(w io.Writer, format string) (io.WriteCloser, error) {
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switch format {
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case "gz":
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return gzip.NewWriter(w), nil
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case "xz":
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return xz.NewWriter(w)
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case "none", "":
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return &nopCloser{w}, nil
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default:
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return nil, fmt.Errorf("unsupported compression format: %q", format)
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}
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}
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// Compress compresses data using the specified format.
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func Compress(data []byte, format string) ([]byte, error) {
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var buf bytes.Buffer
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var writer io.WriteCloser
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var err error
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switch format {
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case "gz":
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writer = gzip.NewWriter(&buf)
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case "xz":
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writer, err = xz.NewWriter(&buf)
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if err != nil {
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return nil, err
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}
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default:
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return data, nil
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}
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_, err = writer.Write(data)
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if err != nil {
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return nil, err
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}
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err = writer.Close()
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if err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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// Decompress decompresses data, detecting the format automatically.
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func Decompress(data []byte) ([]byte, error) {
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// Check for gzip header
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if len(data) > 2 && data[0] == 0x1f && data[1] == 0x8b {
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reader, err := gzip.NewReader(bytes.NewReader(data))
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if err != nil {
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return nil, err
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}
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defer reader.Close()
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return io.ReadAll(reader)
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}
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// Check for xz header
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if len(data) > 6 && data[0] == 0xfd && data[1] == '7' && data[2] == 'z' && data[3] == 'X' && data[4] == 'Z' && data[5] == 0x00 {
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reader, err := xz.NewReader(bytes.NewReader(data))
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if err != nil {
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return nil, err
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}
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return io.ReadAll(reader)
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}
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return data, nil
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}
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